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  • 2005-2009  (158)
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  • Knowledge management.
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Years
Year
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  • 101
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    Jahresbericht 2004 (2005)
    Details
    Publication Date: 2019-10-24
    Keywords: ddc:000
    Language: German
    Type: annualzib , doc-type:report
    Format: application/pdf
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  • 102
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    Ranking: Google und CiteSeer (2005)
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    Publication Date: 2014-02-26
    Description: Im Rahmen des klassischen Information Retrieval wurden verschiedene Verfahren für das Ranking sowie die Suche in einer homogenen strukturlosen Dokumentenmenge entwickelt. Die Erfolge der Suchmas chine Google haben gezeigt, dass die Suche in einer zwar inhomogenen aber zusammenhängenden Dokumentenmenge wie dem Internet unter Berücksichtigung der Dokumentenverbindungen (Links) sehr ef fektiv sein kann. Unter den von der Suchmaschine Google realisierten Konzepten ist ein Verfahren zum Ranking von Suchergebnissen (PageRank), das in diesem Artikel kurz erklärt wird. % Darüber hinaus wird auf die Konzepte eines Systems namens CiteSeer eingegangen, welches automatisch bibliographische Angaben indexiert (engl. \glqq Autonomous Citation Indexing\grqq, ACI). Letzteres erzeugt aus einer Menge von nicht-vernetzten wissenschaftlichen Dokumenten eine zusammenhängende Dokumentenmenge und ermöglicht den Einsatz von Ranking-Verfahren, die auf den von Google genutzten Verfahren basieren.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 103
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    Superlinear Convergence of the Control Reduced Interior Point Method for PDE Constrained Optimization (2005)
    Details
    Publication Date: 2019-01-29
    Description: A thorough convergence analysis of the Control Reduced Interior Point Method in function space is performed. This recently proposed method is a primal interior point pathfollowing scheme with the special feature, that the control variable is eliminated from the optimality system. Apart from global linear convergence we show, that this method converges locally almost quadratically, if the optimal solution satisfies a function space analogue to a non-degeneracy condition. In numerical experiments we observe, that a prototype implementation of our method behaves in compliance with our theoretical results.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 104
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    Anisotropic Smoothing of Point Sets (2005)
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    Publication Date: 2014-02-26
    Description: The use of point sets instead of meshes became more popular during the last years. We present a new method for anisotropic fairing of a point sampled surface using an anisotropic geometric mean curvature flow. The main advantage of our approach is that the evolution removes noise from a point set while it detects and enhances geometric features of the surface such as edges and corners. We derive a shape operator, principal curvature properties of a point set, and an anisotropic Laplacian of the surface. This anisotropic Laplacian reflects curvature properties which can be understood as the point set analogue of Taubin's curvature-tensor for polyhedral surfaces. We combine these discrete tools with techniques from geometric diffusion and image processing. Several applications demonstrate the efficiency and accuracy of our method.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 105
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    Fare Planning for Public Transport (2005)
    Details
    Publication Date: 2020-12-15
    Description: In this paper we introduce the fare planning problem for public transport which consists in designing a system of fares maximizing revenue. We propose a new simple general model for this problem. It i s based on a demand function and constraints for the different fares. The constraints define the structure of the fare system, e.g., distance dependent fares or zone fares. We discuss a simple example with a quadratic demand function and distance dependent fares. Then we introduce a more realistic discrete choice model in which passengers choose between different alternatives depending on the numb er of trips per month. We demonstrate the examples by computational experiments.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 106
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    Public Transport to the fORe! (2005)
    Details
    Publication Date: 2020-12-15
    Description: Can OR methods help the public transport industry to break even? The article gives evidence that there exist significant potentials in this direction, which can be harnessed by a combination of modern mathematical methods and local planning knowledge. Many of the planning steps in public transport are classical combinatorial problems, which can be solved in unprecedented size and quality due the rapid progress in large-scale optimization. Three examples on vehicle scheduling, duty scheduling, and integrated vehicle and duty scheduling illustrate the level that has been reached and the improvements that can be achieved today. Extensions of such methods to further questions of strategic, online, and market-oriented planning are currently investigated. In this way, OR can make a significant contribution to answer the basic but extremely difficult question ``What is a good public transport network?.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 107
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    A spectral order method for inverting sectorial Laplace transforms (2005)
    Details
    Publication Date: 2016-06-09
    Description: Laplace transforms which admit a holomorphic extension to some sector strictly containing the right half plane and exhibiting a potential behavior are considered. A spectral order, parallelizable method for their numerical inversion is proposed. The method takes into account the available information about the errors arising in the evaluations. Several numerical illustrations are provided.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 108
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    A Column Generation Approach to Airline Crew Scheduling (2005)
    Details
    Publication Date: 2020-03-09
    Description: The airline crew scheduling problem deals with the construction of crew rotations in order to cover the flights of a given schedule at minimum cost. The problem involves complex rules for the legality and costs of individual pairings and base constraints for the availability of crews at home bases. A typical instance considers a planning horizon of one month and several thousand flights. We propose a column generation approach for solving airline crew scheduling problems that is based on a set partitioning model. We discuss algorithmic aspects such as the use of bundle techniques for the fast, approximate solution of linear programs, a pairing generator that combines Lagrangean shortest path and callback techniques, and a novel rapid branching'' IP heuristic. Computational results for a number of industrial instances are reported. Our approach has been implemented within the commercial crew scheduling system NetLine/Crew of Lufthansa Systems Berlin GmbH.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 109
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    Conformation Kinetics as a Reduced Model for Transition Pathways (2005)
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    Publication Date: 2014-03-10
    Description: The complexity of molecular kinetics can be reduced significantly by a restriction to metastable conformations which are almost invariant sets of molecular dynamical systems. With the Robust Perron Cl uster Analysis PCCA+, developed by Weber and Deuflhard, we have a tool available which can be used to identify these conformations from a transition probability matrix. This method can also be applied to the corresponding transition rate matrix which provides important information concerning transition pathways of single molecules. In the present paper, we explain the relationship between these tw o concepts and the extraction of conformation kinetics from transition rates. Moreover, we show how transition rates can be approximated and conclude with numerical examples.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 110
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    Die Vision einer individuellen quantitativen Medizin (2005)
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    Publication Date: 2020-03-09
    Description: Die Autoren schreiben dieses Papier aus der eingeschränkten Sicht der Mathematik und der Informationstechnik. Um den speziellen Beitrag dieser Disziplinen überhaupt diskutieren zu können, sehen wir uns jedoch gezwungen, einen Rahmen abzustecken, den wir für das Jahr 2020 vorhersehen -- nach Wahrscheinlichkeit und aus unserem engeren fachlichen Blickwinkel. Vorab bitten wir schon einmal bei den medizinischen Fachleuten um Nachsicht, wenn wir uns in ihrem Revier allzu dillettantisch bewegen. Vielleicht fördert aber auch unser eingeschränkter Blickwinkel ansonsten unbedachte Aspekte zutage -- das hoffen wir zumindest.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 111
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    On weakly non-local, nilpotent, and super-recursion operators for N=1 super-equations (2005)
    Details
    Publication Date: 2014-02-26
    Description: We consider nonlinear, scaling-invariant $N=1$ boson$+$fermion supersymmetric systems whose right-hand sides are homogeneous differential polynomials and satisfy some natural assumptions. We select the super-systems that admit infinitely many higher symmetries generated by recursion operators; we further restrict ourselves to the case when the dilaton dimensions of the bosonic and fermionic super-fields coincide and the weight of the time is half the weight of the spatial variable. We discover five systems that satisfy these assumptions; one system is transformed to the purely bosonic Burgers equation. We construct local, nilpotent, triangular, weakly non-local, and super-recursion operators for their symmetry algebras.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 112
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    A Branch-And-Cut for the Maximum Feasible Subsystem Problem (2005)
    Details
    Publication Date: 2020-12-15
    Description: We present a branch-and-cut algorithm for the NP-hard maximum feasible subsystem problem: For a given infeasible linear inequality system, determine a feasible subsystem containing as many inequalities as possible. The complementary problem, where one has to remove as few inequalities as possible in order to render the system feasible, can be formulated as a set covering problem. The rows of this formulation correspond to irreducible infeasible subsystems, which can be exponentially many. The main issue of a branch-and-cut algorithm for MaxFS is to efficiently find such infeasible subsystems. We present three heuristics for the corresponding NP-hard separation problem and discuss further cutting planes. This paper contains an extensive computational study of our implementation on a variety of instances arising in a number of applications.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 113
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    Supersymmetric representations and integrable super-extensions of the Burgers and Boussinesq equations (2005)
    Details
    Publication Date: 2014-02-26
    Description: New evolutionary supersymmetric systems whose right-hand sides are homogeneous differential polynomials and which possess infinitely many higher symmetries are constructed. Their intrinsic geometry (symmetries, conservation laws, recursion operators, Hamiltonian structures, and exact solutions) is analyzed by using algebraic methods. A supersymmetric $N=1$ representation of the Burgers equation is obtained. An $N=2$ KdV-component system that reduces to the Burgers equation in the diagonal $N=1$ case $\theta^1=\theta^2$ is found; the $N=2$ Burgers equation admits and $N=2$ modified KdV symmetry. A one\/-\/parametric family of $N=0$ super\/-\/systems that exte nd the Burgers equation is described; we relate the systems within this family with the Burgers equation on associative algebras. A supersymmetric boson$+$fermion representation of the dispersionless Boussinesq equation is investigated. We solve this equation explicitly and construct its integrable deformation that generates two infinite sequences of the Hamiltonians. The Boussinesq equation with dispersion is embedded in a one-parametric family of two-component systems with dissipation. We finally construct a three-parametric supersymmetric system that incorporates the Boussinesq equation with dispersion and dissipation but never retracts to it for any values of the parameters.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 114
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    Treewidth Lower Bounds with Brambles (2005)
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    Publication Date: 2014-11-10
    Description: In this paper we present a new technique for computing lower bounds for graph treewidth. Our technique is based on the fact that the treewidth of a graph $G$ is the maximum order of a bramble of $G$ minus one. We give two algorithms: one for general graphs, and one for planar graphs. The algorithm for planar graphs is shown to give a lower bound for both the treewidth and branchwidth that is at most a constant factor away from the optimum. For both algorithms, we report on extensive computational experiments that show that the algorithms give often excellent lower bounds, in particular when applied to (close to) planar graphs.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 115
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    KOBV-Volltextserver - Langfristiger Zugriff auf Kluwer-, Springer- und Elsevier-Zeitschriften (2005)
    Details
    Publication Date: 2020-11-13
    Description: Seit einigen Jahren lizenzieren Bibliotheken mit erheblichem finanziellen Aufwand elektronische Zeitschriften. Anders als bei einer Papierausgabe ist der dauerhafte Zugriff auf die bezahlten Dokumente allerdings nicht garantiert: Die e-Zeitschriften liegen auf dem Verlagsserver, und der Verlag schaltet den Zugriff (meist IP-Range des Campus) auf seinem Server frei. Wird der Zugriff von Verlagsseite abgeschaltet, erlöschen sämtliche Zugriffsrechte, auch auf die in der Vergangenheit lizenzierten und bezahlten Zeitschriften. Auf die neuen Abonnementbedingungen hat das Friedrich-Althoff-Konsortium (FAK) reagiert und in seinen Vertr"agen den Erwerb der Archivdaten beim Auslaufen eines Vertrages festgeschrieben. Im Rahmen eines Projektes baut die KOBV-Zentrale einen Zeitschriftenserver auf, um den Zugriff auf die lizenzierten elektronischen Zeitschriften auch nach Ablauf der Lizenzverträge zu gewährleisten. Den Grundstock bilden die vom FAK in den Jahren 1997-2003 lizenzierten elektronischen Zeitschriften der Verlage Kluwer Academic Press, Springer und Elsevier - ein Volumen von rund 1.600 Zeitschriftentiteln mit knapp 1.400.000 Artikeln. Beim Aufbau des Zeitschriftenservers kommt der vertraglich-organisatorischen Komponente eine ebenso wichtige Rolle zu wie der technischen Realisierung. Hier hat die KOBV-Zentrale ein transparentes Verfahren konzipiert und umgesetzt, um für die Verlage die notwendige Vertrauensbasis zu schaffen und gleichzeitig den Einrichtungen ihren berechtigten Zugriff auf die Zeitschriften-Volltexte zu sichern. Die Zeitschriftenartikel werden sowohl im Rahmen des KOBV-Volltextservers, einem neuen Internet-Dienst der KOBV-Zentrale, zugänglich gemacht - volltext-indiziert mit der Suchmaschine Swish-e - als auch integriert in die Metadatensuche und den Open-Linking-Dienst des KOBV-Portals. Während die Metadatenrecherche und die Sicht auf die Abstracts für alle offen sind, ist der Zugriff auf die Artikel-Volltexte auf die an den Verträgen beteiligten Einrichtungen beschränkt. Dazu wurde ein Authentifizierungsverfahren auf der Basis von IP-Ranges eingerichtet. Der vorliegende Text ist die schriftliche Fassung eines gleichnamigen Vortrages auf der ASpB-Tagung 2005 \glqq Spezialbibliotheken zwischen Auftrag und Ressourcen{\grqq} der Arbeitsgemeinschaft der Spezialbibliotheken, die vom 06.-09. September 2005 in der Technischen Universität München stattfand.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 116
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    Verteilter Dokumenten Speicher: Erfahrungen mit der Suchmaschine Fast (2005)
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    Publication Date: 2014-02-26
    Description: In diesem Bericht wurden Erfahrungen mit der Suchmaschine FAST im Rahmen des Projektes Verteilter Contentspeicher sowie die Suchmaschine FAST beschrieben. Das Ziel des Projektes Verteilter Contentspeicher war die Speicherung, Erschließung und das Angebot der digitalen Bestände der Journale und Dokumente der KOBV-Bibliotheken zu ermöglichen. Die Eignung der Suchmaschine FAST für das Projektvorhaben wurde systematisch und gründlich getestet, indem verschiedene Dokumentmengen mit FAST indexiert wurden.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 117
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    Rapid Mathematical Programming (2005)
    Details
    Publication Date: 2020-02-11
    Description: The thesis deals with the implementation and application of out-of-the-box tools in linear and mixed integer programming. It documents the lessons learned and conclusions drawn from five years of implementing, maintaining, extending, and using several computer codes to solve real-life industrial problems. By means of several examples it is demonstrated how to apply algebraic modeling languages to rapidly devise mathematical models of real-world problems. It is shown that today's MIP solvers are capable of solving the resulting mixed integer programs, leading to an approach that delivers results very quickly. Even though, problems are tackled that not long ago required the implementation of specialized branch-and-cut algorithms. In the first part of the thesis the modeling language Zimpl is introduced. Chapter 2 contains a complete description of the language. In the subsequent chapter details of the implementation are described. Both theoretical and practical considerations are discussed. Aspects of software engineering, error prevention, and detection are addressed. In the second part several real-world projects are examined that employed the methodology and the tools developed in the first part. Chapter 4 presents three projects from the telecommunication industry dealing with facility location problems. Chapter 5 characterizes questions that arise in UMTS planning. Problems, models, and solutions are discussed. Special emphasis is put on the dependency of the precision of the input data and the results. Possible reasons for unexpected and undesirable solutions are explained. Finally, the Steiner tree packing problem in graphs, a well-known hard combinatorial problem, is revisited. A formerly known, but not yet used model is applied to combine switchbox wire routing and via minimization. All instances known from the literature are solved by this approach, as are some newly generated bigger problem instances.
    Keywords: ddc:000
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 118
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    Online-Optimization of Multi-Elevator Transport Systems with Reoptimization Algorithms based on Set-Partitioning Models (2005)
    Details
    Publication Date: 2014-02-26
    Description: We develop and experimentally compare policies for the control of a system of $k$ elevators with capacity one in a transport environment with $\ell$ floors, an idealized version of a pallet elevator system in a large distribution center of the Herlitz PBS AG in Falkensee. Each elevator in the idealized system has an individual waiting queue of infinite capacity. On each floor, requests arrive over time in global waiting queues of infinite capacity. The goal is to find a policy that, without any knowledge about future requests, assigns an elevator to each req uest and a schedule to each elevator so that certain expected cost functions (e.g., the average or the maximal flow times) are minimized. We show that a reoptimization policy for minimizing average sq uared waiting times can be implemented to run in real-time ($1\,s$) using dynamic column generation. Moreover, in discrete event simulations with Poisson input it outperforms other commonly used polic ies like multi-server variants of greedy and nearest neighbor.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 119
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    Partial and complete linearization of PDEs based on conservation laws (2005)
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    Publication Date: 2014-02-26
    Description: A method based on infinite parameter conservation laws is described to factor linear differential operators out of nonlinear partial differential equations (PDEs) or out of differential consequences of nonlinear PDEs. This includes a complete linearization to an equivalent linear PDE (-system) if that is possible. Infinite parameter conservation laws can be computed, for example, with the computer algebra package {\sc ConLaw}.
    Keywords: ddc:000
    Language: English
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  • 120
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    Some classifications of hyperbolic vector evolution equations (2005)
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    Publication Date: 2022-03-11
    Description: Motivated by recent work on integrable flows of curves and 1+1 dimensional sigma models, several $O(N)$-invariant classes of hyperbolic equations $Utx=f(U,Ut,Ux)$ for an $N$-component vector $U(t,x)$ are considered. In each class we find all scaling-homogeneous equations admitting a higher symmetry of least possible scaling weight. Sigma model interpretations of these equations are presented.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 121
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    Integrable quadratic Hamiltonians with a linear Lie-Poisson bracket (2005)
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    Publication Date: 2014-02-26
    Description: Quadratic Hamiltonians with a linear Lie-Poisson bracket have a number of applications in mechanics. For example, the Lie-Poisson bracket $e(3)$ includes the Euler-Poinsot model describing motion of a rigid body around a fixed point under gravity and the Kirchhoff model describes the motion of a rigid body in ideal fluid. Advances in computer algebra algorithms, in implementations and hardware, together allow the computation of Hamiltonians with higher degree first integrals providing new results in the search for integrable models. A computer algebra module enabling related computations in a 3-dimensional vector formalism is described.
    Keywords: ddc:000
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  • 122
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    Fast and oblivious convolution quadrature (2005)
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    Publication Date: 2016-06-09
    Description: We give an algorithm to compute $N$ steps of a convolution quadrature approximation to a continuous temporal convolution using only $O(N\, \log N)$ multiplications and $O(\log N)$ active memory. The method does not require evaluations of the convolution kernel, but instead $O(\log N)$ evaluations of its Laplace transform, which is assumed sectorial. The algorithm can be used for the stable numerical solution with quasi-optimal complexity of linear and nonlinear integral and integro-differential equations of convolution type. In a numerical example we apply it to solve a subdiffusion equation with transparent boundary conditions.
    Keywords: ddc:000
    Language: English
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  • 123
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    FeedbackFlow - An Adaptive Workflow Generator for System Management (2005)
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    Publication Date: 2014-02-26
    Description: We describe a prototypical framework that further automates system management by composing complex management tasks from elementary actions, and executing composite tasks with feedback-awareness. {\sl FEEDBACKFLOW} implements a general closed control loop of \emph{planning - execution - result validation - replanning}, and generates workflows of system management actions in an adaptive manner. System-dependent behaviour of the loop is specified by declarative description of the domain (essentially descriptions of available actions), and statement of the goal. We evaluate the design of this framework on examples taken from resource construction in Utility Computing environments, and discuss the challenges we have encountered. Our implementation utilizes external components such as \emph{MBP}, a \emph{PDDL}-conform planner, and \emph{Triana}, a workflow specification and execution framework. An alternative approach involving \emph{BPEL4WS} is discussed.
    Keywords: ddc:000
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  • 124
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    A Case Study of Joint Online Truck Scheduling and Inventory Management for Multiple Warehouses (2005)
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    Publication Date: 2014-02-26
    Description: For a real world problem --- transporting pallets between warehouses in order to guarantee sufficient supply for known and additional stochastic demand --- we propose a solution approach via convex relaxation of an integer programming formulation, suitable for online optimization. The essential new element linking routing and inventory management is a convex piecewise linear cost function that is based on minimizing the expected number of pallets that still need transportation. For speed, the convex relaxation is solved approximately by a bundle approach yielding an online schedule in 5 to 12 minutes for up to 3 warehouses and 40000 articles; in contrast, computation times of state of the art LP-solvers are prohibitive for online application. In extensive numerical experiments on a real world data stream, the approximate solutions exhibit negligible loss in quality; in long term simulations the proposed method reduces the average number of pallets needing transportation due to short term demand to less than half the number observed in the data stream.
    Keywords: ddc:000
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  • 125
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    ZIBgridfree - Adaptive Conformation Analysis with qualified Support of Transition States and Thermodynamic Weights (2005)
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    Publication Date: 2014-02-26
    Description: This paper introduces a new algorithm of conformational analysis based on mesh-free methods as described in [M. Weber. Mehless methods in Conformation Dynamics.(2005)]. The adaptive decomposition of the conformational space by softly limiting functions avoids trapping effects and allows adaptive refinement strategies. These properties of the algorithm makes ZIBgridfree particularly suitable for the complete exploration of high-dimensional conformational space. The adaptive control of the algorithm benefits from the tight integration of molecular simulation and conformational analysis. An emphasized part of the analysis is the Robust Perron Cluster Analysis (PCCA+) based on the work of Peter Deuflhard and Marcus Weber. PCCA+ supports an almost-characteristic cluster definition with an outstanding mapping of transition states. The outcome is expressed by the metastable sets of conformations, their thermodynamic weights and flexibility.
    Keywords: ddc:000
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  • 126
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    MIPLIB 2003 (2005)
    Details
    Publication Date: 2021-08-05
    Description: This paper reports on the fourth version of the Mixed Integer Programming Library. Since ({\sc miplib}) is to provide a concise set of challenging problems, it became necessary to purge instances that became too easy. We present an overview of the 27 new problems and statistical data for all 60 instances.
    Keywords: ddc:000
    Language: English
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    Optimierte Tagesplanung im Berliner Trinkwassernetz (2005)
    Details
    Publication Date: 2021-02-01
    Description: Der Artikel beschreibt ein mathematisches Optimierungssystem zur Betriebsplanung in großen Wassernetzen, das bei den Berliner Wasserbetrieben eingesetzt wird. Für das Berliner Versorgungsnetz werden Optimierungsergebnisse vorgestellt.
    Keywords: ddc:000
    Language: German
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    Der KOBV-Metadaten-Austausch-Parser (KMA-Parser): Ein Werkzeug für Metadata-Sharing (2005)
    Details
    Publication Date: 2014-02-26
    Description: \\ Zusammenfassung: Der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) betreibt für das KOBV-Portal einen Austausch von Beschreibungen zu elektronischen Ressourcen (Metadaten), der zwisc zwischen verschiedenen Informationsportalen in der Region durchgeführt wird. Die unterschiedlichen Informationsportale verwenden verschiedene Metadaten-Schemata und Austausch-Formate für ihre Ressourcebeschreibungen. Um die Heterogenität der Metadaten zu überwinden, wurde der KOBV-Metadaten-Austausch-Parser (KMA-Parser) entwickelt. Andere Metadaten-Schemata werden auf das KOBV-Metadaten-Schema abgebildet. Der KMA-Parser führt gegebenenfalls eine Format-Transformation durch, konvertiert die Inhalte einzelner Elemente über Konkordanzen und erzeugt neue Metadaten-Elemente aus vorhandenen Feldern. Er validiert den Inhalt auf Vollständigkeit und steuert den Austausch der Metadaten zwischen den Portalen. Der Umwandlungsprozess funktioniert jedoch nicht nur in die Richtung des KOBV-Portals, sondern auch in die entgegengesetzte Richtung. Der Artikel beschreibt die einzelnen Vorgänge im KMA-Parser und schildert die Erfahrungen im Umgang mit der Heterogenität von Metadaten. Die gewonnenen Erfahrungen verweisen auf grundlegende Perspektiven in der universellen Zusammenarbeit von Informationsanbietern und -providern.The Kooperativer Bibliotheksverbund Berlin-Brandenburg (KOBV) has built a framework for a bi-directional exchange workflow of electronic resourcesÆ descriptions (metadata) between the KOBV Portal and other Information Portals in the region. The Information Portals use different exchange formats, metadata schemata and controlled vocabularies for their descriptions of resources. In order to overcome this metadata heterogeneity, an application, the KOBV Metadata Exchange Parser (KMA-Parser), has been developed. The KMA-Parser maps the local portalsÆ metadata schemata into the metadata schema of the KOBV Portal. If necessary, it transforms the exchange format, converts contents of individual elements by means roduces new metadata elements on the basis of existent elements. It checks elementsÆ contents on completeness and controls the metadata exchange between the portals. However, the transformation process takes place not only towards the KOBV Portal, but al so vice versa. The article describes the individual processes in the KMA Parser and depicts the experiences in handling the metadataÆs heterogeneity. The experiences gathered give an idea of the prospects for a universal cooperation between information suppliers and providers.
    Keywords: ddc:000
    Language: German
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    Chord#: Structured Overlay Network for Non-Uniform Load-Distribution (2005)
    Details
    Publication Date: 2021-01-22
    Description: \newcommand{\chordsharp}{Chord$^\##$} Data lookup is a fundamental problem in peer-to-peer systems: Given a key, find the node that stores the associated object. Chord and other P2P algorithms use distributed hash tables (DHTs) to distribute the keys and nodes evenly across a logical ring. Using an efficient routing strategy, DHTs provide a routing performance of $O (\log N)$ in networks of $N$ nodes. While the routing performance has been shown to be optimal, the uniform key distribution makes it impossible for DHTs to support range queries. For range queries, consecutive keys must be stored on lo gically neighboring nodes. In this paper, we present an enhancement of Chord that eliminates the hash function while keeping the same routing performance. The resulting algorithm, named \chordsharp{}, provides a richer function ality while maintaining the same complexity. In addition to Chord, \chordsharp{} adapts to load imbalance.
    Keywords: ddc:000
    Language: English
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  • 130
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    On the Interplay Between Interior Point Approximation and Parametric Sensitivities in Optimal Control (2005)
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    Publication Date: 2019-01-29
    Description: This paper is concerned with the sensitivities of function space oriented interior point approximations in parameter dependent problems. For an abstract setting that covers control constrained optimal control problems, the convergence of interior point sensitivities to the sensitivities of the optimal solution is shown. Error bounds for $L_q$ norms are derived and illustrated with numerical examples.
    Keywords: ddc:000
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  • 131
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    An Auctioning Approach to Railway Slot Allocation (2005)
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    Publication Date: 2020-08-05
    Description: We present an approach to implement an auction of railway slots. Railway network, train driving characteristics, and safety requirements are described by a simplified, but still complex macroscopic model. In this environment, slots are modelled as combinations of scheduled track segments. The auction design builds on the iterative combinatorial auction. However, combinatorial bids are restricted to some types of slot bundles that realize positive synergies between slots. We present a bidding language that allows bidding for these slot bundles. An integer programming approach is proposed to solve the winner determination problem of our auction. Computational results for auction simulations in the Hannover-Fulda-Kassel area of the German railway network give evidence that auction approaches can induce a more efficient use of railway capacity.
    Keywords: ddc:000
    Language: English
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  • 132
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    Schnelle Rundreisen: Das Travelling Salesman-Problem (2005)
    Details
    Publication Date: 2014-02-26
    Description: Das Travelling-Salesman-Problem (TSP) ist das am intensivsten untersuchte kombinatorische Optimierungsproblem. In diesem Abschnitt wird eine Einführung in das TSP gegeben. Es werden Problemstellungen erläutert, Anwendungen skizziert und einige Schwierigkeiten bei der korrekten Modellierung der Zielfunktion dargelegt. Es ist gar nicht so klar, was in einem konkreten Problem die wirkliche Entfernung ist. Exakte und approximative Lösungsverfahren werden an Beispielen skizziert, und es wird angedeutet, dass man, obwohl TSPs zu den theoretisch schweren Problemen zählen, in der Praxis TSPs von atemberaubender Größe lösen kann.
    Keywords: ddc:000
    Language: German
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  • 133
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    Abschlußbericht des DFN-Projekts "Virtueller Supercomputer Berlin - Hannover" (2005)
    Details
    Publication Date: 2014-02-26
    Description: Mit der Installation des neuen Hochleistungsrechners für die norddeutschen Länder (HLRN) steht den Wissenschaftlern ein außergewöhnlich leistungsfähiges System zur Verfügung. Durch die Verteilung der Rechenelemente auf zwei verschiedene Standorte in Berlin (ZIB) und Hannover (RRZN) entstehen jedoch auch neue Herausforderungen für den Betrieb und die effiziente Nutzung des Rechners. Inhalt dieses Projektes ist die Erforschung und Lösung der durch die Verteilung des Systems hervorgerufenen Probleme (z.B. Scheduling, Kommunikation, I/O). Es werden effiziente Lösungen zur Bereitstellung eines virtuellen, hoch-performanten und transparenten Systems entwickelt, die auf vergleichbare Installationen übertragbar sind.
    Keywords: ddc:000
    Language: German
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  • 134
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    Inapproximability Results for the Inverse Shortest Paths Problem with Integer Length and Unique Shortest Paths (2005)
    Details
    Publication Date: 2014-11-10
    Description: We study the complexity of two Inverse Shortest Paths (ISP) problems with integer arc lengths and the requirement for uniquely determined shortest paths. Given a collection of paths in a directed graph, the task is to find positive integer arc lengths such that the given paths are uniquely determined shortest paths between their respective terminals. The first problem seeks for arc lengths that minimize the length of the longest of the prescribed paths. In the second problem, the length of the longest arc is to be minimized. We show that it is $np-hard$ to approximate the minimal longest path length within a factor less than $8/7$ or the minimal longest arc length within a factor less than $9/8$. This answers the (previously) open question whether these problems are $np-hard$ or not. We also present a simple algorithm that achieves an $\mathcal{O}(|V|)$-approximation guarantee for both variants. Both ISP problems arise in the planning of telecommunication networks with shortest path routing protocols. Our results imply that it is $\mathcal{NP}$-hard to decide whether a given path set can be realized with a real shortest path routing protocol such as OSPF, IS-IS, or RIP.
    Keywords: ddc:000
    Language: English
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  • 135
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    Classification of polynomial integrable systems of mixed scalar and vector evolution equations. I (2005)
    Details
    Publication Date: 2014-02-26
    Description: We perform a classification of integrable systems of mixed scalar and vector evolution equations with respect to higher symmetries. We consider polynomial systems that are homogeneous under a suitable weighting of variables. This paper deals with the KdV weighting, the Burgers (or potential KdV or modified KdV) weighting, the Ibragimov--Shabat weighting and two unfamiliar weightings. The case of other weightings will be studied in a subsequent paper. Making an ansatz for undetermined coefficients and using a computer package for solving bilinear algebraic systems, we give the complete lists of $2^{\mbox{\scriptsize nd }}$order systems with a $3^{\mbox{\scriptsize rd }}$order or a $4^{\mbox{\scriptsize th }}$order symmetry and $3^{\mbox{\scriptsize rd }}$order systems with a $5^{\mbox{\scriptsize th }}$order symmetry. For all but a few systems in the lists, we show that the system (or, at least a subsystem of it) admits either a Lax representation or a linearizing transformation. A thorough comparison with recent work of Foursov and Olver is made.
    Keywords: ddc:000
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  • 136
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    Fast Runge-Kutta approximation of inhomogeneous parabolic equations (2005)
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    Publication Date: 2014-02-26
    Description: The result after $N$ steps of an implicit Runge-Kutta time discretization of an inhomogeneous linear parabolic differential equation is computed, up to accuracy $\varepsilon$, by solving only $$O\Big(\log N\, \log \frac1\varepsilon \Big) $$ linear systems of equations. We derive, analyse, and numerically illustrate this fast algorithm.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 137
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    Wavelength Assignment in Multi-Fiber WDM Networks by Generalized Edge Coloring (2005)
    Details
    Publication Date: 2020-11-13
    Description: In this paper, we study wavelength assignment problems in multi-fiber WDM networks. We focus on the special case that all lightpaths have at most two links. This in particular holds in case the network topology is a star. As the links incident to a specific node in a meshed topology form a star subnetwork, results for stars are also of interest for general meshed topologies. We show that wavelength assignment with at most two links per lightpath can be modeled as a generalized edge coloring problem. By this relation, we show that for a network with an even number of fibers at all links and at most two links per lightpath, all lightpaths can be assigned a wavelength without conversion. Moreover, we derive a lower bound on the number of lightpaths to be converted for networks with arbitrary numbers of fibers at the links. A comparison with linear programming lower bounds reveals that the bounds coincide for problems with at most two links per lightpath. For meshed topologies, the cumulative lower bound over all star subnetworks equals the best known solution value for all realistic wavelength assignment instances available, by this proving optimality.
    Keywords: ddc:000
    Language: English
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  • 138
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    Two New Bounds for the Random-Edge Simplex Algorithm (2005)
    Details
    Publication Date: 2014-11-21
    Description: We prove that the Random-Edge simplex algorithm requires an expected number of at most $13n/sqrt(d)$ pivot steps on any simple d-polytope with n vertices. This is the first nontrivial upper bound for general polytopes. We also describe a refined analysis that potentially yields much better bounds for specific classes of polytopes. As one application, we show that for combinatorial d-cubes, the trivial upper bound of $2^d$ on the performance of Random-Edge can asymptotically be improved by any desired polynomial factor in d.
    Keywords: ddc:000
    Language: English
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  • 139
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    Modellierung und Optimierung der X-WiN Plattform (2005)
    Details
    Publication Date: 2014-11-10
    Description: In diesem Artikel werden die Optimierungsmodelle und -verfahren beschrieben, die bei der Planung des Kernnetzes und der Zugangsinfrastruktur des X-WiN verwendet wurden.
    Keywords: ddc:000
    Language: German
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  • 140
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    Entwicklung und Aufbau des Internet-Dienstes "Math&Industry" (2005)
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    Publication Date: 2014-02-26
    Description: Die Anwendung mathematischer Methoden und Verfahren wird immer mehr zur Voraussetzung innovativer Produkte und Dienstleistungen. Um neue Produkte und Dienstleistungen zu entwickeln, müssen die Produktions- und technologischen Prozesse mathematisch modelliert, beschrieben und optimiert werden. Diesen Umstand Rechnung tragend, hat das Bundesministerium für Bildung und Forschung (BMBF) 1993 begonnen, den Einsatz mathematischer Verfahren und Methoden in der Mathematik über ein spezielles Mathematikprogramm zu fördern. Inzwischen hat die vierte Förderperiode des Mathematikprogramms begonnen. \par Das Medium Internet und insbesondere das WWW sind für die Sichtbarkeit und Transparenz wissenschaftlicher Resultate in den letzten zehn Jahren immer wichtiger geworden. Wer nicht im Web "'sichtbar"' ist, läuft Gefahr, nicht wahrgenommen zu werden. Intention und Ziel des durchgeführten Projekts war es, ein Konzept für eine qualitativ hochwertige und umfassende Darstellung des BMBF Mathematikprogramms, insbesondere der in den Projekten erzielten Ergebnisse, zu entwickeln und zu realisieren und damit den Stellenwert und die Akzeptanz mathematischer Forschung in der Gesellschaft zu festigen und den Wissenstransfer zwischen mathematischer Forschung sowie Forschung und Entwicklung in der Wirtschaft und dem Dienstleistungsbereich zu fördern.
    Keywords: ddc:000
    Language: German
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  • 141
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    Aufbau einer verteilten Fachredaktion für freie Internet-Ressourcen im KOBV-Portal (2005)
    Details
    Publication Date: 2014-02-26
    Description: Die KOBV-Zentrale betreibt mit dem KOBV-Portal neben der Metasuche in freien Online-Katalogen und Datenbanken ein Nachweisinstrument für elektronische Ressourcen, die von den Bibliotheken Berlin-Brandenburgs lizenziert sind und darüber hinaus diejenigen, die frei zugänglich sowie wissenschaftlich relevant sind. Die Erschließung der freien Ressourcen übernimmt eine kooperative Fachredaktion, die sich aus FachreferentInnen und -lektorInnen aus der Region rekrutiert. Dabei übernimmt jede beteiligte Person die Betreuung einer oder mehrerer Fachgruppen der Dewey Decimal-Classification (DDC) eigenverantwortlich. Die Aufgabe aller FachredakteurInnen besteht in der inhaltlichen Beschreibung, der Klassifizierung, der Vergabe von Schlagworten und der regelmäßigen Reevaluation der einzelnen Ressourcen. Die KOBV-Zentrale hat hierfür einen Kriterienkatalog entwickelt, der als Grundlage für die Beurteilung von elektronischen Ressourcen dient. Erschlossen werden die Ressourcen schließlich über ein webbasierte Eingabe-Tool, dem Metadata-Tool der KOBV-Zentrale. Über eine Mailingliste wird der Abstimmungsbedarf untereinander gedeckt und Diskussionen geführt, die das Projekt weiterführen sollen. Der Artikel beschreibt das Konzept der kooperativen Fachredaktion für freie Ressourcen, die Vorgänge und die Arbeiten, die für die Initiierung notwendig waren.
    Keywords: ddc:000
    Language: German
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  • 142
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    Evolution of 3d Curves under Strict Spatial Constraints (2005)
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    Publication Date: 2014-02-26
    Description: We present a new algorithm for fairing of space curves with respect spatial constraints based on a vector valued curvature function. Smoothing with the vector valued curvature function is superior to standard Frenet techniques since the individual scalar components can be modeled similar to curvature-based curve smoothing techniques in 2d. This paper describes a curve smoothing flow that satisfies strict spatial constraints and allows simultaneous control of both curvature functions.
    Keywords: ddc:000
    Language: English
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  • 143
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    Additive Schwarz method for scattering problems using the PML method at interfaces (2005)
    Details
    Publication Date: 2016-06-09
    Description: Scattering problems in integrated optics can be modeled in simple cases by the Helmholtz equation. The computational domain is truncated by a non-reflecting boundary condition. We investigate Schwarz algorithms with a sort of DtN operator, realized by the PML-method, at the interfaces of the sub-domains as an iterative solver.
    Keywords: ddc:000
    Language: English
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  • 144
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    Adaptivity in Space and Time for Reaction-Diffusion Systems in Electrocardiology (2005)
    Details
    Publication Date: 2019-05-10
    Description: Adaptive numerical methods in space and time are introduced and studied for multiscale cardiac reaction-diffusion models in three dimensions. The evolution of a complete heartbeat, from the excitation to the recovery phase, is simulated with both the anisotropic Bidomain and Monodomain models, coupled with either a variant of the simple FitzHugh-Nagumo model or the more complex phase-I Luo-Rudy ionic model. The simulations are performed with the {\sc kardos} library, that employs adaptive finite elements in space and adaptive linearly implicit methods in time. The numerical results show that this adaptive method successfully solves these complex cardiac reaction-diffusion models on three-dimensional domains of moderate sizes. By automatically adapting the spatial meshes and time steps to the proper scales in each phase of the heartbeat, the method accurately resolves the evolution of the intra- and extra-cellular potentials, gating variables and ion concentrations during the excitation, plateau and recovery phases.
    Keywords: ddc:000
    Language: English
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    Nonlinear Programming Techniques for Operative Planning in Large Drinking Water Networks (2005)
    Details
    Publication Date: 2021-02-01
    Description: Mathematical decision support for operative planning in water supply systems is highly desirable but leads to very difficult optimization problems. We propose a nonlinear programming approach that yields practically satisfactory operating schedules in acceptable computing time even for large networks. Based on a carefully designed model supporting gradient-based optimization algorithms, this approach employs a special initialization strategy for convergence acceleration, special minimum up and down time constraints together with pump aggregation to handle switching decisions, and several network reduction techniques for further speed-up. Results for selected application scenarios at Berliner Wasserbetriebe demonstrate the success of the approach.
    Keywords: ddc:000
    Language: English
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    Foundations of Hierarchical SAT-Solving (2005)
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    Publication Date: 2014-02-26
    Description: The theory of hierarchical Boolean satisfiability (SAT) solving proposed in this paper is based on a strict axiomatic system and introduces a new important notion of implicativity. The theory makes evident that increasing implicativity is the core of SAT-solving. We provide a theoretical basis for increasing the implicativity of a given SAT instance and for organizing SAT-solving in a hierarchical way. The theory opens a new domain of research: SAT-model construction. Now quite different mathematical models can be used within practical SAT-solvers. The theory covers many advanced techniques such as circuit-oriented SAT-solving, mixed BDD/CNF SAT-solving, merging gates, using pseudo-Boolean constraints, using state machines for representation of Boolean functions, arithmetic reasoning, and managing don t cares. We believe that hierarchical SAT-solving is a cardinal direction of research in practical SAT-solving.
    Keywords: ddc:000
    Language: English
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    Optimal Fares for Public Transport (2005)
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    Publication Date: 2020-12-15
    Description: The \emph{fare planning problem} for public transport is to design a system of fares that maximize the revenue. We introduce a nonlinear optimization model to approach this problem. It is based on a d iscrete choice logit model that expresses demand as a function of the fares. We illustrate our approach by computing and comparing two different fare systems for the intercity network of the Netherlands.
    Keywords: ddc:000
    Language: English
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    Routing in Line Planning for Public Transportation (2005)
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    Publication Date: 2020-12-15
    Description: The line planning problem is one of the fundamental problems in strategic planning of public and rail transport. It consists in finding lines and corresponding frequencies in a network such that a giv en demand can be satisfied. There are two objectives. Passengers want to minimize travel times, the transport company wishes to minimize operating costs. We investigate three variants of a multi-commo dity flow model for line planning that differ with respect to passenger routings. The first model allows arbitrary routings, the second only unsplittable routings, and the third only shortest path rou tings with respect to the network. We compare these models theoretically and computationally on data for the city of Potsdam.
    Keywords: ddc:000
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    Online-Fernleihe im KOBV - Handbuch für Bibliotheken (2005)
    Details
    Publication Date: 2020-11-13
    Description: \documentclass[12pt]{article} \usepackage{german} \parindent=0pt \begin{document} Im KOBV wird für die Online-Fernleihe der Zentrale-Fernleihserver (ZFL-Server) der Firma Sisis eingesetzt. Die Software ist in der KOBV-Zentrale installiert. Der ZFL-Server dient im KOBV sowohl für die Bestellung von Monographien als auch für die Bestellung von Aufsatzkopien aus Zeitschriften. Prinzipiell gibt es zwei Verfahren, mit denen sich Bibliotheken an der Online-Fernleihe beteiligen können: das E-Mail-Verfahren und das SLNP-Verfahren. Auf beide wird im Handbuch eingegangen. Die Online-Fernleihe wurde im KOBV eingeführt, um die Fernleihe für die Benutzer zu beschleunigen, das Verfahren für die Bibliotheksmitarbeiter zu vereinfachen und den Arbeitsaufwand zu reduzieren. Sie basiert darauf, dass eine Bestellung anhand eines gefundenen Treffers ausgelöst wird - d.h. die bibliographischen Daten sind bereits verifiziert und in einem Katalog nachgewiesen. Anschlie\"send werden die Fernleihbestellungen über den ZFL-Server automatisch ausgeführt und verwaltet - sowohl in der regionalen KOBV-Fernleihe als auch in der verbundübergreifenden Fernleihe mit den deutschen Bibliotheksverbünden. Der ZFL-Server besteht aus verschiedenen technischen Komponenten. Eine dieser Komponenten ist das Bibliothekskonto, eine Internetanwendung, in der die Bestellverwaltung des ZFL-Servers im Internet für die Bibliotheksbediensteten transparent gemacht wird. Sowohl für die aktive als auch für die passive Fernleihe ist im Bibliothekskonto der Status der Bearbeitung zu jedem Zeitpunkt ersichtlich, z.B. in welcher Bibliothek sich die Bestellung gerade befindet, wann sie dort eingegangen ist und wann sie weggeschickt wurde, ob mit positivem oder negativem Ergebnis. Das Bibliothekskonto ist damit für die Bibliothek ein komfortables Instrument zum Überwachen der Fernleihbestellungen, in dem sie zudem - falls notwendig - in den Bestellvorgang eingreifen kann. Dazu hat jede Bibliothek im Bibliothekskonto eine eigene, Passwort-geschützte Dienstoberfläche. Das vorliegende Handbuch beschreibt die Vorgänge der Bestellverwaltung im Bibliothekskonto. Es richtet sich an Bibliotheksmitarbeiter, die sich mit den einzelnen Arbeitsschritten der Online-Fernleihe vertraut machen wollen. Darüber hinaus ist es zum Nachschlagen gedacht, wenn sich in der täglichen Arbeit Unklarheiten ergeben. \end{document}
    Keywords: ddc:000
    Language: German
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  • 150
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    Improving the Feasibility Pump (2005)
    Details
    Publication Date: 2022-03-14
    Description: The Feasibility Pump of Fischetti, Glover, Lodi, and Bertacco has proved to be a very successful heuristic for finding feasible solutions of mixed integer programs. The quality of the solutions in terms of the objective value, however, tends to be poor. This paper proposes a slight modification of the algorithm in order to find better solutions. Extensive computational results show the success of this variant: in 89 out of 121 MIP instances the modified version produces improved solutions in comparison to the original Feasibility Pump.
    Keywords: ddc:000
    Language: English
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  • 151
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    Probing the Aoki phase with N_f=2 Wilson fermions at finite temperature (2005)
    Details
    Publication Date: 2014-02-26
    Description: In this letter we report on a numerical investigation of the Aoki phase in the case of finite temperature which continues our former study at zero temperature. We have performed simulations with Wilson fermions at $\beta=4.6$ using lattices with temporal extension $N_{\tau}=4$. In contrast to the zero temperature case, the existence of an Aoki phase can be confirmed for a small range in $\kappa$ at $\beta=4.6$, however, shifted slightly to lower $\kappa$. Despite fine-tuning $\kappa$ we could not separate the thermal transition line from the Aoki phase.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 152
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    Topological Index Criteria in DAE for Water Networks (2005)
    Details
    Publication Date: 2021-02-01
    Description: The dynamics of pressurized water distribution networks are naturally modeled by differential algebraic equations (DAE). This paper investigates fundamental structural properties of such a DAE model under weak regularity assumptions. The usual partial derivative-based index-1 condition is shown to be necessary and sufficient for several index concepts, as well as sufficient for solvability in a strong sense. Using the physical properties of nonlinear network elements and the inherent saddle point structure of network hydraulics, we then derive purely topological index criteria based on the network graph and the choice of control variables. Several examples illustrate the theoretical results and explore different non-index-1 situations. A brief discussion of the implications for operative planning by discrete time DAE boundary value problems concludes the paper.
    Keywords: ddc:000
    Language: English
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  • 153
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    Rapid Mathematical Programming or How to Solve Sudoku Puzzles in a few Seconds (2005)
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    Publication Date: 2020-02-11
    Description: Using the popular puzzle game of Sudoku, this article highlights some of the ideas and topics covered in ZR-04-58.
    Keywords: ddc:000
    Language: English
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  • 154
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    Comparing Imperfection Ratio and Imperfection Index for Graph Classes (2005)
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    Publication Date: 2021-03-16
    Description: Perfect graphs constitute a well-studied graph class with a rich structure, reflected by many characterizations with respect to different concepts. Perfect graphs are, for instance, precisely those graphs $G$ where the stable set polytope $STAB(G)$ coincides with the fractional stable set polytope $QSTAB(G)$. For all imperfect graphs $G$ it holds that $STAB(G) \subset QSTAB(G)$. It is, therefore, natural to use the difference between the two polytopes in order to decide how far an imperfect graph is away from being perfect; we discuss three different concepts, involving the facet set of $STAB( G)$, the disjunctive index of $QSTAB(G)$, and the dilation ratio of the two polytopes. Including only certain types of facets for $STAB(G)$, we obtain graphs that are in some sense close to perfect graphs, for example minimally immperfect graphs, and certain other classes of so-called rank-perfect graphs. The imperfection ratio has been introduced by (Gerke and McDiarmid, 2001) as the dilation ratio of $STAB(G)$ and $QSTAB(G)$, whereas (Aguilera et al., 2003) suggest to take the disjunctive index of $Q STAB(G)$ as the imperfection index of $G$. For both invariants there exist no general upper bounds, but there are bounds known for the imperfection ratio of several graph classes (Coulonges et al. 2005, Gerke and McDiarmid, 2001). Outgoing from a graph-theoretical interpretation of the imperfection index, we conclude that the imperfection index is NP-hard to compute and we prove that there exists no upper bound on the imperfect ion index for those graph classes with a known bounded imperfection ratio. Comparing the two invariants on those classes, it seems that the imperfection index measures imperfection much more roughly than the imperfection ratio; therefoe, discuss possible directions for refinements.
    Keywords: ddc:000
    Language: English
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  • 155
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    The Online Target Date Assignment Problem (2005)
    Details
    Publication Date: 2020-11-13
    Description: Many online problems encountered in real-life involve a two-stage decision process: upon arrival of a new request, an irrevocable first-stage decision (the assignment of a specific resource to the request) must be made immediately, while in a second stage process, certain ``subinstances'' (that is, the instances of all requests assigned to a particular resource) can be solved to optimality (offline) later. We introduce the novel concept of an \emph{Online Target Date Assignment Problem} (\textsc{OnlineTDAP}) as a general framework for online problems with this nature. Requests for the \textsc{OnlineTDAP} become known at certain dates. An online algorithm has to assign a target date to each request, specifying on which date the request should be processed (e.\,g., an appointment with a customer for a washing machine repair). The cost at a target date is given by the \emph{downstream cost}, the optimal cost of processing all requests at that date w.\,r.\,t.\ some fixed downstream offline optimization problem (e.\,g., the cost of an optimal dispatch for service technicians). We provide general competitive algorithms for the \textsc{OnlineTDAP} independently of the particular downstream problem, when the overall objective is to minimize either the sum or the maximum of all downstream costs. As the first basic examples, we analyze the competitive ratios of our algorithms for the par ticular academic downstream problems of bin-packing, nonpreemptive scheduling on identical parallel machines, and routing a traveling salesman.
    Keywords: ddc:000
    Language: English
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  • 156
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    Beleuchtung von Landschaften in interaktiver Darstellung (2005)
    Details
    Publication Date: 2022-07-19
    Description: Inhalt dieser Diplomarbeit ist ein Beleuchtungs- und Visualisierungsmodell für Pflanzen im interaktiven Landschaftsrendering. Ziel ist die qualitativ hochwertige Darstellung von einzelnen Individuen nahe des Betrachters, der seine Position in einer ansonsten statischen Szene frei wählen kann. Um dies zu erreichen wird zunächst vorgestellt, wie ausgehend von einfachen 3D-Modellen und Materialien ein physikalisch basiertes Reflexionsmodell parametrisiert werden kann. Grund hierfür ist der oftmals vorhandene umfangreiche Datenbestand, der auf die OpenGL-Materialien oder ähnliche Shader optimiert ist. Anschließend wird gezeigt, wie die Echtzeit-Renderingtechniken Shadow Mapping und Precomputed Radiance Transfer kombiniert werden können, um sowohl exakte hochfrequente direkte Beleuchtung als auch niederfrequentes indirektes Streulicht zu berücksichtigen. Diese Kombination wird an Hand der Pfad-Notation des Monte-Carlo-Path-Tracing eingeführt und begründet.
    Keywords: ddc:000
    Language: German
    Type: masterthesis , doc-type:masterThesis
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  • 157
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    Einbettung neuer Verwaltungsmethoden in die hierarchische Dateisystemsicht (2005)
    Details
    Publication Date: 2024-02-09
    Description: Die hierarchische Organisation von Dateien beherrscht Computersysteme seit vielen Jahren und wird sich vermutlich auch in Zukunft weiterhin durchsetzen. Dennoch stößt diese Verwaltungsmethode in einem klassischen hierarchischen Dateisystem bei dem jährlichen rasanten Zuwachs an neuen Daten an ihre Grenzen, auch wenn Nutzer eine ausgefeilte Verzeichnisstruktur mit einer disziplinierten Namensgebung konsequent auf- und ausbauen. Um den Überblick über die Dateien zu behalten, werden in dieser Arbeit neue Verwaltungsmethoden vorgestellt und in die hierarchische Dateisystemsicht eingebettet. Auf der Basis des hierarchischen Dateisystems bietet ein metadatenbasiertes Dateisystem neben dem hierarchischen Zugriff noch einen flexiblen, assoziativen Zugriff auf Dateien über virtuelle Objekte, indem Suchmethoden in Form einer Anfrage auf in einer Datenbank gespeicherte Index- und Metadaten angewendet werden. Das Ergebnis dieser Abfrage wird mit Hilfe von virtuellen Verzeichnissen und virtuellen Dateien in einer übersichtlichen Form dargestellt, so dass eine Nutzung der hierarchischen Sicht weiterhin intuitiv fortgesetzt wird. Das Datenmanagementsystem ZIBDMS, welches einen verteilten Metadatenkatalog und einen Dateireplikationskatalog beinhaltet, ermöglicht es, die oben genannten Verwaltungsmethoden für die NFS-Schnittstelle, CORBA-Middleware und Web Services transparent zu implementieren. Zudem stellt ZIBDMS weitere neue Dateiverwaltungsmethoden zur Verfügung, die sich in die hierarchische Dateisystemsicht integrieren lassen. Metadaten in Form von Attribut-Wert-Paaren lassen sich als virtuelle Datei darstellen und editieren. Eine Collection bietet die Möglichkeit, Dateien in einem logischen virtuellen Ordner zu organisieren. Mit einem Dependency-Graph lassen sich Dateien zueinander in Relation stellen, so dass eine Linkstruktur zwischen Dateien ausgedrückt werden kann. Das Verweiskonzept eines klassischen hierarchischen Dateisystems wird im ZIBDMS um eine neue Verweisart Weak-Link erweitert, um einen aktualisierbaren, konsistenten und zyklenfreien symbolischen Link anzubieten. In einer hierarchischen Sicht lässt sich durch Verweise ein Baum bilden, in dem eine Navigation und Verweisauflistung möglich sind, was außer ZIBDMS noch kein anderes System bietet.
    Description: The hierarchical organization of files has dominated computer systems for many years and this will probably not change in the near future. However, with the rapid annual growth of new data this classical hierarchical file system management method reaches its limitations, even when the user consistently sets up and continually expands an elaborated directory structure with well-disciplined naming. This paper introduces new management methods to maintain an overview of all files which can be embedded in the hierarchical file system. A metadata-based file system, which is based on the hierarchical file system, offers, in addition to hierarchical access, a more flexible and associative access to files via virtual objects by providing query capabilities of index- and metadata which are stored in a database. The query results are presented in a clearly-arranged form of virtual directories and virtual files so that the intuitive hierarchical view continues to be maintained. The data management system ZIBDMS, which contains a distributed metadata catalog and a file replication catalog, permits a transparent implementation of these management methods for the NFS interface, CORBA-middleware or web services. Furthermore, ZIBDMS provides other new file management methods that can be integrated into the hierarchical file system view. Metadata in form of attribute-value-pairs can be presented and edited with a virtual file. A Collection makes it possible to organize files in logical virtual folders. Using a Dependency graph, files can be related to each other and expressed through a link structure between these files. In the ZIBDMS the reference concept of a classical hierarchal file system is extended with a new kind of reference called Weak Link in order to provide up-to-date, consistent and cycle-free symbolic links. With the references a tree can be established in a hierarchical view in which navigation and listing of references are possible; this capability is only possible in the ZIBDMS system.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 158
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    Unknown
    Einbettung neuer Verwaltungsmethoden in die hierarchische Dateisystemsicht (2005)
    Details
    Publication Date: 2024-02-09
    Description: Die hierarchische Organisation von Dateien beherrscht Computersysteme seit vielen Jahren und wird sich vermutlich auch in Zukunft weiterhin durchsetzen. Dennoch stößt diese Verwaltungsmethode in einem klassischen hierarchischen Dateisystem bei dem jährlichen rasanten Zuwachs an neuen Daten an ihre Grenzen, auch wenn Nutzer eine ausgefeilte Verzeichnisstruktur mit einer disziplinierten Namensgebung konsequent auf- und ausbauen. Um den Überblick über die Dateien zu behalten, werden in dieser Arbeit neue Verwaltungsmethoden vorgestellt und in die hierarchische Dateisystemsicht eingebettet. Auf der Basis des hierarchischen Dateisystems bietet ein metadatenbasiertes Dateisystem neben dem hierarchischen Zugriff noch einen flexiblen, assoziativen Zugriff auf Dateien über virtuelle Objekte, indem Suchmethoden in Form einer Anfrage auf in einer Datenbank gespeicherte Index- und Metadaten angewendet werden. Das Ergebnis dieser Abfrage wird mit Hilfe von virtuellen Verzeichnissen und virtuellen Dateien in einer übersichtlichen Form dargestellt, so dass eine Nutzung der hierarchischen Sicht weiterhin intuitiv fortgesetzt wird. Das Datenmanagementsystem ZIBDMS, welches einen verteilten Metadatenkatalog und einen Dateireplikationskatalog beinhaltet, ermöglicht es, die oben genannten Verwaltungsmethoden für die NFS-Schnittstelle, CORBA-Middleware und Web Services transparent zu implementieren. Zudem stellt ZIBDMS weitere neue Dateiverwaltungsmethoden zur Verfügung, die sich in die hierarchische Dateisystemsicht integrieren lassen. Metadaten in Form von Attribut-Wert-Paaren lassen sich als virtuelle Datei darstellen und editieren. Eine Collection bietet die Möglichkeit, Dateien in einem logischen virtuellen Ordner zu organisieren. Mit einem Dependency-Graph lassen sich Dateien zueinander in Relation stellen, so dass eine Linkstruktur zwischen Dateien ausgedrückt werden kann. Das Verweiskonzept eines klassischen hierarchischen Dateisystems wird im ZIBDMS um eine neue Verweisart Weak-Link erweitert, um einen aktualisierbaren, konsistenten und zyklenfreien symbolischen Link anzubieten. In einer hierarchischen Sicht lässt sich durch Verweise ein Baum bilden, in dem eine Navigation und Verweisauflistung möglich sind, was außer ZIBDMS noch kein anderes System bietet.
    Description: The hierarchical organization of files has dominated computer systems for many years and this will probably not change in the near future. However, with the rapid annual growth of new data this classical hierarchical file system management method reaches its limitations, even when the user consistently sets up and continually expands an elaborated directory structure with well-disciplined naming. This paper introduces new management methods to maintain an overview of all files which can be embedded in the hierarchical file system. A metadata-based file system, which is based on the hierarchical file system, offers, in addition to hierarchical access, a more flexible and associative access to files via virtual objects by providing query capabilities of index- and metadata which are stored in a database. The query results are presented in a clearly-arranged form of virtual directories and virtual files so that the intuitive hierarchical view continues to be maintained. The data management system ZIBDMS, which contains a distributed metadata catalog and a file replication catalog, permits a transparent implementation of these management methods for the NFS interface, CORBA-middleware or web services. Furthermore, ZIBDMS provides other new file management methods that can be integrated into the hierarchical file system view. Metadata in form of attribute-value-pairs can be presented and edited with a virtual file. A Collection makes it possible to organize files in logical virtual folders. Using a Dependency graph, files can be related to each other and expressed through a link structure between these files. In the ZIBDMS the reference concept of a classical hierarchal file system is extended with a new kind of reference called Weak Link in order to provide up-to-date, consistent and cycle-free symbolic links. With the references a tree can be established in a hierarchical view in which navigation and listing of references are possible; this capability is only possible in the ZIBDMS system.
    Keywords: ddc:000
    Language: German
    Type: masterthesis , doc-type:masterThesis
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  • 159
    Electronic Resource
    Electronic Resource
    Carotid artery stenosis and tachyarrhythmias: regional cerebral blood flow during high-rate ventricular pacing after one vessel occlusion in rats (1994)
    Springer
    Journal of molecular medicine 72 (1994), S. 775-781 
    Details
    ISSN: 1432-1440
    Keywords: Cerebral blood flow ; Carotid stenosis ; Microspheres ; Ventricular tachycardia ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of the present study was to investigate the effect of hypotensive tachycardias on cerebral blood flow (CBF) in the presence of significant carotid stenosis. The experiments were performed in 57 spontaneously breathing rats during arterial normoxia and normocapnia anesthetized with thiobarbital. CBF was determined with radio-labeled microspheres during control conditions (normofrequent sinus rhythm, normotension; group A; n = 15), during high-rate left ventricular pacing (660–840 ppm) at normotension (group B1; n = 13), borderline hypotension (group B2; n = 15) and severe hypotension (group B3; n = 7). In addition, CBF measurements were performed during borderline hypotension induced by hemorrhage (group C; n = 7). Global CBF was 1.09 ± 0.29 ml g−1 min−1 in group A, 0.93 ± 0.40 in group B1, 0.68 ± 0.31 in group B2 (P 〈 0.05 vs. A), 0.42 ± 0.16 in group B3 (P 〈 0.05 vs. A) and 0.83 ± 0.2 in group C. The highest CBF values were found in the cerebellum (A; 1.43 ± 0.5 ml g−1 min−) and the lowest in the postocclusive tissue of the ipsilateral hemisphere (A; 0.74 ± 0.2 ml g−1 min−1). In all groups a 15% mean CBF reduction in the right hemispherical cerebrum in comparison to the left hemisphere was observed (P 〈 0.01). In contrast, hemispherical CBF of the cerebellum did not differ. The CBF blood pressure relationship shifted to lower CBF values, the threshold of CBF regulation shifted to higher blood pressure values in the tissue regions distal to the occluded vessel during hypotensive tachycardias. One carotid artery occlusion and high rate ventricular pacing seem to be a reliable model for quantifying cerebral hemodynamics during arrhythmias in the presence of carotid stenoses. Using this experimental approach it was demonstrated that hypotensive tachycardias and obstructions within the ectracranial carotid vascular bed such as arterial vessel stenoses and occlusions have an additive effect on CBF reduction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00180546
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  • 160
    Electronic Resource
    Electronic Resource
    Evaluation of methotrexate tissue exposure by in situ microdialysis in a rat model (1994)
    Springer
    Cancer chemotherapy and pharmacology 34 (1994), S. 297-301 
    Details
    ISSN: 1432-0843
    Keywords: Microdialysis ; Methotrexate ; Tissue ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The feasibility of using a microdialysis technique to obtain pharmacokinetic data on tissue exposure to methotrexate (MTX) was investigated. Microdialysis probes were implanted in the jugular vein, femoral muscle, and liver ofanesthetized male Wistar rats. MTX (100 mg/kg) was given as a bolus injection through an indwelling venous catheter, and blood samples were obtained through a second venous access and by microdialysis for a total of 6 h. Heparinized plasma, ultrafiltered plasma, and microdialysis effluent from tissue and venous probes were analyzed by high-performance liquid chromatography. Centrifugal ultrafiltration of rat plasma spiked in vitro with MTX (1–100 μM) revealed a mean binding to plasma proteins of 21%. In vitro microdialysis of this spiked plasma resulted in 23% relative recovery of the unbound fraction. In rats receiving MTX, plasma protein binding was 23% and the relative drug recovery as assessed with venous microdialysis probes was 18%. Plotting of unbound (i.e., ultrafiltrate) MTX concentrations in the blood against venous microdialysis perfusate values in the blood gave a good linear correlation with a coefficient of correlation (r 2) of 0.98. There was also a linear correlation between the total MTX concentrations in venous blood and the drug levels in microdialysis samples from muscle and liver (r 2=0.93 and 0.74, respectively). Area under the curve estimations were consistent with an MTX exposure of 30% and 46% for the muscle and liver as compared with the circulation. The present study demonstrates that the microdialysis technique can provide reproducible data on tissue exposure to MTX in an animal model and indicates that the methodology is adaptable to clinical settings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00686036
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  • 161
    Electronic Resource
    Electronic Resource
    Soluble factors produced by macrophages/monocytes inhibit lymphokine-activated killer activity in rat splenocyte cultures (1994)
    Springer
    Cancer immunology immunotherapy 38 (1994), S. 61-67 
    Details
    ISSN: 1432-0851
    Keywords: Lymphokine-activated killer activity ; Interleukin-2 ; 2-Mercaptoethanol ; Macrophages/monocytes ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the present study we investigated the inhibition of interleukin-2(IL-2)-induced lymphokine-activated killer (LAK) activity in rat splenocyte cultures in relation to the presence of 2-mercaptoethanol and macrophages/monocytes. The presence of 2-mercaptoethanol is necessary for induction of LAK activity in rat splenocyte cultures. Removal of macrophages/monocytes from rat splenocytes by plastic or nylon-wool adherence, or iron ingestion resulted in LAK induction by IL-2 in the absence of 2-mercaptoethanol. The effect of macrophages/monocytes on LAK activity was also studied in transwell co-cultures. In the absence of 2-mercaptoethanol, the induction of LAK activity was very low in macrophage/monocyte-depleted splenocytes with macrophages/monocytes in the upper compartment of a transwell culture. In contrast, in the presence of 2-mercaptoethanol a high level of LAK activity was induced in these transwell cultures, showing that 2-mercaptoethanol abolished the LAK-inhibiting capacity of macrophages/monocytes. In addition, established LAK activity was strongly inhibited when, after LAK induction, splenocytes were cultured with supernatant of unfractionated splenocytes, which were cultured with IL-2 but in the absence of 2-mercaptoethanol. Addition of 2-mercaptoethanol abrogated the inhibiting effect of the supernatant completely. These experiments demonstrate that rat macrophages/monocytes produce 2-mercaptoethanolsensitive soluble LAK-inhibiting factors. Ultrafiltration of conditioned culture medium of macrophages/monocytes revealed the presence of LAK-inhibiting factors larger than 10 kDa. We concluded that 2-mercaptoethanol-sensitive soluble factors produced by macrophages/monocytes determine the level of LAK induction in rat splenocyte cultures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01517171
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  • 162
    Electronic Resource
    Electronic Resource
    Effects of fasting on haematology and clinical chemistry values in the rat and dog (1994)
    Springer
    Comparative clinical pathology 4 (1994), S. 152-156 
    Details
    ISSN: 1433-2981
    Keywords: Clinical chemistry ; Dog ; Fasting ; Haematology ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Many regulatory toxicity guidelines and the recommendation of AACC-DACC/ASVCP joint task force of the USA on clinical pathology testing require overnight fasting for rats and non-rodents before blood sampling. However, the reason why animals must be fasted before blood sampling is unclear in toxicology studies. Fasting, one of many preanalytical conditions, can lead to false low or high values, which in turn may lead to misinterpretation of test compound effects in toxicological studies. This paper reviews the literature with respect to fasting, and reports on our own studies, in the hope of increasing the awareness among investigators of these problems. Haematocrit values and plasma chemistry values in blood obtained from rats and dogs following fasting were compared with unfasted animals. In male F344 rats, after 16 h fasting, body weight decreased. Increases in aspartate aminotransferase (AST)/glutamic oxaloacetic transaminase (GOT) and decreases of plasma alkaline phosphatase (ALP), total cholesterol (CHO), triglycerides (TG), phospholipids (PL), urea nitrogen (UN) and calcium were observed. Haematocrit, plasma alanine aminotransferase (ALT)/glutamic pyruvic transaminase (GPT), total proteins (TP), glucose, and inorganic phosphorus (IP) were unchanged. In male beagle dogs after 16 h fasting, TG, PL, UN, calcium and IP were decreased. Haematocrit, ALP, TP, albumin, glucose, CHO, creatinine, AST/GOT, ALT/GPT, LDH and CPK were not changed. Our own studies show that in order to avoid excessive stress to test animals, the fasting period should be decided case by case, and not made uniform in toxicology studies. It would be useful if regulatory guidelines made some mention of both the effect of feeding, and of stress caused by fasting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00798356
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  • 163
    Electronic Resource
    Electronic Resource
    Prothrombin times and activated partial thromboplastin times in toxicology: a comparison of different blood withdrawal sites for wistar rats (1994)
    Springer
    Comparative clinical pathology 4 (1994), S. 173-176 
    Details
    ISSN: 1433-2981
    Keywords: APTT ; Blood withdrawal ; PT ; Rat ; Sysmex CA-5000
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The prothrombin time (PT) and the activated partial thromboplastin time (APTT) for untreated male Wistar rats were determined on the Sysmex CA-5000 Instrument for blood taken from the orbital sinus, tail vein, vena cava and aorta. Boxplot and statistical analysis was performed. Only orbital sinus puncture yields unpredictable and unacceptable variation/prolongation of clotting times.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00798360
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  • 164
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    Comparative NMR studies of diffusional water permeability of erythrocytes from some animals introduced to Australia: Rat rabbit and sheep (1994)
    Springer
    Comparative clinical pathology 4 (1994), S. 232-235 
    Details
    ISSN: 1433-2981
    Keywords: NMR ; Rabbit ; Rat ; Red blood cells ; Sheep ; Water permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The diffusional water permeability (P d) of the red blood cell (RBC) membrane of rat, rabbit and sheep, representing some animal species introduced to Australia, has been monitored, by a Mn2+-doping 1H nuclear magnetic resonance (NR) technique using a high-field spectometer operating at 400 MHz. In order to make comparisons with previous measurements on the same species (performed at 25 MHz) an analysis of the influence of instrumental parameters and of the state of blood oxygenation was performed on samples of rat and rabbit blood. It was found that by using a short interpulse delay (around 100 µs) in the Carr-Purcell-Meiboom-Gill sequence, and by performing the measurements of the transverse relaxation time of the water in the cell interior (T 2i) on packed cells (haematocrit 〉95%), the values of the water exchange time (T e) obtained with a high-field spectrometer are comparable with those obtained by using a low-field NMR spectrometer. The values of the diffusional water permeability (P d), calculated from the T e values, were, at 24.6°C around 10 × 10−3 cm/s in case of rat and rabbit RBC and around 5 × 10−3 cm/s for sheep RBC; at 37°C the P d values were around 16 × 10−3 cm/s for rat RBC, 14 × 10−3 cm/s for rabbit RBC and 7 × 10−3 cm/s for sheep RBC. These values are very close to the P d values previously reported for the European counterparts of these species. There were no significant differences in the P d values between laboratory rabbits and wild rabbits, or between castrated males, pregnant or nonpregnant females. These results suggest that no changes in the RBC water permeability are correlated with marked alterations in the habitat of animal species introduced to Australia or by sex hormone status. If the NMR instrument-parameters are carefully chosen then comparative studies of RBC water permeability in different laboratories, at separate locations and using different instruments are meaningful.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185179
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  • 165
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    The immune response in lymphoid organs of rat: A cytochemical study (1994)
    Springer
    Comparative clinical pathology 4 (1994), S. 37-42 
    Details
    ISSN: 1433-2981
    Keywords: Escherichia coli ; Immunisation ; Lymphoid organs ; Rat ; Tissue Enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Variations in the activity of lactate dehydrogenase (LDH), succinate dehydrogenase (SDH), dihydrofolate reductase (DHFR) and alkaline phosphatase (ALP) were studied, using the light microscope (LM), and cytochemical reactions in lymphoid organs (lymph node, spleen, thymus) of rats, up to day 5 following Escherichia coli immunisation. Increased levels of LDH and DHFR in the T-area of lymph nodes and of spleen were seen from day 2 to day 4 postimmunisation. The SDH reaction in lymph nodes and in the spleen increased during days 2 and 3 but decreased on day 4 postimmunisation. Considerable increases in the activities of LDH and SDH were seen in thymus at all times postimmunisation. The DHFR reaction product also increased but less markedly. No reaction for ALP was observed in lymphocytes of lymphoid organs studied. Following E. coli immunisation, there is an increase in glycolytic and respiratory metabolism, and in the synthesis of proteins in T-dependent areas of lymphoid organs. These increases are correlated with immune activation of T-cells in these organs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00368265
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  • 166
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    Immunocytochemical and ultrastructural heterogeneities of normal and glibenclamide stimulated pancreatic beta cells in the rat (1994)
    Springer
    Virchows Archiv 425 (1994), S. 305-313 
    Details
    ISSN: 1432-2307
    Keywords: Rat ; Pancreatic beta cells ; Immunocytochemistry ; Ultrastructure ; Insulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract When studied morphologically in semi-thin sections in the rat in vivo, pancreatic beta cells displayed heterogeneous immunoreactivities for insulin and amylin, depending on the islet size and the intra-islet position of the beta cells. In larger islets, cortical beta cells (beta cells with contacts with all islet cell types and with the exocrine parenchyma) which are located in the periphery were more densely immunostained for insulin and amylin than medullary beta cells (beta cells with contacts only with other beta cells) which are located in the centre of the islet. Ultrastructurally, these findings were accompanied by differences in the number of secretory granules and mitochondria. Beta cells in small islets and at extra-islet sites exhibited a dense immunoreactivity. After administration of glibenclamide, immunoreactivities for insulin and amylin were diminished in a time-dependent manner, decreasing first in medullary and thereafter in cortical beta cells of larger islets. Ultrastructurally, the beta cells exhibited the typical signs of stimulation. A minority of beta cells in small islets and all beta cells in extra-islet locations remained unchanged. Thus pancreatic beta cells under basal and stimulatory conditions in vivo exhibit heterogeneity in hormone content and in ultrastructural features. These differences may represent the basis for a functional heterogeneity of the insulin secretory response of the individual beta cell both in vivo and in vitro in states of normal and impaired insulin secretion. As heterogeneity was observed only among beta cells in islets, while single beta cells surrounded by acinar cells exhibited no changes in insulin immunoreactivity, interactions between beta cells as well as between beta cells and other endocrine cells may be critical for expression of heterogeneity within the beta cell population.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196154
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  • 167
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    Elevated concentrations of the β-subunit of S100 protein in renal cell tumors in rats (1994)
    Springer
    Urological research 22 (1994), S. 251-255 
    Details
    ISSN: 1434-0879
    Keywords: S100 protein ; Rat ; Carcinogenesis ; Renal neoplasms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Concentrations of α and β-subunits of S100 protein (S100-α and S100-β) in rat kidney neoplasms, including renal cell and mesenchymal tumors, were determined using a highly sensitive enzyme immunoassay, and both types immunohistochemically localized in tissue sections. Concentration of S100-α in each histological type of rat tumor were lower than in normal kidney, whereas levels of S100-β (mean±SE: 29.7±14.2 ng/mg protein, n=15) in renal cell tumors were significantly higher than in normal kidneys (0.55±0.06 ng/mg protein, n=7), or mesenchymal tumors (1.21±0.43 ng/mg protein, n=9). In normal rat kidney tissues S100-α was immunohistochemically positive in epithelial cells of the distal tubules, the thin limbs of loops of Henle, and the collecting ducts. No appreciable immunostaining for S100-β was found in any nephron segment. Both S100-α and S100-β were positive for renal cell tumors, indicating new appearance of the latter during renal carcinogenesis in rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00541902
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  • 168
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    Post-irradiation bladder dysfunction: muscle strip findings (1994)
    Springer
    Urological research 22 (1994), S. 51-55 
    Details
    ISSN: 1434-0879
    Keywords: Bladder dysfunction ; Muscle strip ; Rat ; X-irradiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Strips of rat detrusor muscle were studied in an organ bath 6 months after X-irradiation at doses of 15 and 25 Gy; cystometric studies in these animals had shown a persistent and significant reduction in compliance. The organ bath study demonstrated an increase in the purinergie sensitivity of irradiated detrusor muscle as compared with control. This was significant: p〈0.0145 for the 25 Gy dose group (n=8) and p〈0.0456 for the 15 Gy group (n=8) at an α,β-methylene-ATP concentration of 10-4 M (Mann-Whitney U-Test). There was no difference in sensitivity to cholinergic or noradrenergic stimulation, or to electrical stimulation of the transmural nerves. The finding of purinergic hypersensitivity in irradiated muscle, coupled with ultrastructural evidence of a neural injury, raises the interesting possibility that a denervation super-sensitivity phenomenon may contribute to the pathophysiology of post-irradiation bladder dysfunction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431549
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  • 169
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    Pyelonephritis: renal urokinase and sialidase (neuraminidase) activity in rats fed a standard laboratory diet (1994)
    Springer
    Urological research 22 (1994), S. 57-60 
    Details
    ISSN: 1434-0879
    Keywords: Kidney ; Pyelonephritis ; Rat ; Sialidase (neuraminidase) ; Urokinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Renal stone formation can be caused by many different and varied disturbances, some of which are poorly understood. The relationship between urinary infection and renal stone formation has not been completely clarified. It is argued that renal stones form primarily as a consequence of the hydrolysis of urea by the bacterial enzyme urease. However, no explanation is given for microorganisms that produce urease only occasionally or not at all. The question arises as to wheter the infection-induced microorganisms might not be playing a double role in renal stone formation by not only producting urease, but also by affecting in vivo urokinase (UK) and sialidase (SA) activity. With this in mind, the effect of Escherichia coli on renal UK and SA activity has been studied in male rats with a normal diet. The renal UK (P=0.208) and SA (P=0.2135) activities did not differ significantly between the two kidneys of the same rat. In contrast, when drainage from one kidney of a rat was externally obstructed, the UK and SA activities differed significantly between kidneys (P〈0.015). An increase in UK (r=0.6456, P〈0.0001) and SA (r=0.7507, P〈0.0001) activity was observed over time in the obstructed kidney. Subcutaneous injections with E. coli reduced the UK activity of the obstructed kidney significantly (p=0.0171). However, the SA activity remained the same (P=0.3929). This decrease in the UK activity in the presence of microorganisms may result in an increase in the uromucoid concentration, leading to renal stone formation in the presence of increased salt precipitation on the uromucoid as caused by the urease producing microorganisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431551
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  • 170
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    The effect of active immunization against gonadotropin-releasing hormone on the ultrastructure of the rat ventral prostate (1994)
    Springer
    Urological research 22 (1994), S. 107-113 
    Details
    ISSN: 1434-0879
    Keywords: GnRH-DT vaccine ; Testosterone ; Ultrastructure ; Rat ; Prostate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To evaluate the effects of active immunization against gonadotropin-releasing hormone (GnRH) on the ultrastructure of the rat ventral prostate, male Sprague-Dawley rats received three consecutive intramuscular injections of 10 μg/100g body weight (D-Lys6)-GnRH-diphtheria toxoid conjugate (GnRH-DT vaccine). Following immunization, test animals developed sufficiently high antibody titres to block the pituitary gonadal axis. Consequently testosterone values dropped to the levels in castrates. This therapy leads to atrophy of the prostate. Following immunization a strong immunological response, indicating the presence of considerable amounts of a GnRH-like peptide, was observed in the ventral prostates as early as 14 days after the first injection of GnRH-DT. Immunoneutralisation of GnRH-like activity may contribute to the effects observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00311001
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  • 171
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    Glial activation and white matter changes in the rat brain induced by chronic cerebral hypoperfusion: an immunohistochemical study (1994)
    Springer
    Acta neuropathologica 87 (1994), S. 484-492 
    Details
    ISSN: 1432-0533
    Keywords: Rat ; Chronic cerebral hypoperfusion ; Glial activation ; White matter changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Activation of glial cells and white matter changes (rarefaction of the white matter) induced in the rat brain by permanent bilateral occlusion of the commom carotid arteries were immunohistochemically investigated up to 90 days. One day after ligation of the arteries, expression of the major histocompatibility complex (MHC) class I antigen in microglia increased in the white matter including the optic nerve, optic tract, corpus callosum, internal capsule, anterior commissure and traversing fiber bundles of the caudoputamen. After 3 days of occlusion, MHC class I antigen was still elevated and in addition MHC class II antigen and leukocyte common antigen were up-regulated in the microglia in these same regions. Astroglia, labeled with glial fibrillary acidic protein, increased in number in these regions after 7 days of occlusion. A few lymphocytes, labeled with CD4 or CD8 antibodies, were scattered in the neural parenchyma 1 h after occlusion. Activation of glial cells and infiltration of lymphocytes persisted after 90 days of occlusion in the white matter and the retinofugal pathway. However, cellular activation and infiltration in microinfarcts of the gray matter was less extensive and was substantially diminished 30 days after occlusion. The white matter changes were most intense in the optic nerve and optic tract, moderate in the medial part of the corpus callosum, internal capsule and anterior commissure, and slight in the fiber bundles of the caudoputamen. These results indicated that chronic cerebral hypoperfusion induced glial activation preferentially in the white matter. This activation seemed to be an early indicator of the subsequent changes in the white matter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00294175
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  • 172
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    The effect of focal cerebral cooling on perinatal hypoxic-ischemic brain damage (1994)
    Springer
    Acta neuropathologica 87 (1994), S. 598-604 
    Details
    ISSN: 1432-0533
    Keywords: KeyWordsIschemia ; Hypothermia ; Brain Immature ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We describe a method of focal cooling of the head and its effects on hypoxic-ischemic cerebral damage in neonatal rat. Focal cooling of the head was obtained by positioning a catheter under the scalp ipsilateral to the ligated common carotid artery and by running cold water through the catheter during 2 h of systemic hypoxia. Hypoxia was produced in neonatal rats by breathing 8   % oxygen for 2 h in a 37 °C chamber. Animals underwent focal cooling with ipsilateral scalp temperatures ranging from 22 °C to 35 °C. Temperature recordings from the ipsilateral scalp, cerebral hemisphere (dorsal hippocampus) and core (rectal) were obtained. The results suggest that the method is effective in cooling of brain and also to a lesser extent in lowering of the core temperature. At a mean scalp temperature of 28 °C, mean hippocampal temperature in hypoxic rat was 29.5 °C and mean core temperature in hypoxic rat was 32.8 °C. At a lower scalp temperature of 22 °C, mean hippocampal temperature in hypoxic rat was 24.7 °C and mean core temperature was 31.3 °C. Neuropathologic examination 3–4 days following hypoxia-ischemia showed that focal cooling with a scalp temperature of lower than 28 °C completely protected from brain damage, and that there was a trend towards greater damage with higher scalp temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293321
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  • 173
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    Permanent increase of immunocytochemical reactivity for g-aminobutyric acid (GABA), glutamic acid decarboxylase, mitochondrial enzymes, and glial fibrillary acidic protein in rat cerebral cortex damaged by early postnatal hypoxia-ischemia (1994)
    Springer
    Acta neuropathologica 87 (1994), S. 612-627 
    Details
    ISSN: 1432-0533
    Keywords: KeyWordsHypoxia-ischemia ; Rat ; Perinatology Cerebral cortex ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A former study indicated that hypoxic-ischemic encephalopathy in rat sustained during early postnatal life may result in permanent epileptic activity in the baseline electroencephalogram. We, therefore, investigated whether the presumed higher firing frequency and metabolic activity of neurons in such hypoxia-damaged cortical areas would be reflected by an enhanced light microscopic immunoreactivity of γ-aminobutyric acid (GABA), the two isoforms of glutamic acid decarboxylase (GAD67 and GAD65), the mitochondrial enzymes cytochrome c oxidase and ATP synthase, and/or glial fibrillary acid, protein (GFAP). To that end rat pups, 12–13 days of age, were unilaterally exposed to hypoxic-ischemic conditions and, after a survival period of 2 and 6--e2--12 months, respectively, killed by perfusion fixation. After dissection of the brain, coronal vibratome sections of animals showing cortical damage were immunostained for the presence of the above-mentioned antigens. Subsequent qualitative analysis revealed that the surroundings of cortical infarctions were unambiguously characterized by a disordered neural network containing numerous nerve cells, fibers and/or endings showing an enhanced immunoreactivity for GABA, both isoforms of glutamic acid decarboxylase, and cytochrome c oxidase and ATP synthase, while the astrocytes showed an enhanced immunoreactivity for GFAP. The diverse patterns of enhanced immunoreactivity suggested, furthermore, a wider low-to-high range of metabolic activities in both excitatory and inhibitory neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293323
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  • 174
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    Electronic Resource
    The effect of focal cerebral cooling on perinatal hypoxic-ischemic brain damage (1994)
    Springer
    Acta neuropathologica 87 (1994), S. 598-604 
    Details
    ISSN: 1432-0533
    Keywords: Ischemia ; Hypothermia ; Brain ; Immature ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We describe a method of focal cooling of the head and its effects on hypoxic-ischemic cerebral damage in neonatal rat. Focal cooling of the head was obtained by positioning a catheter under the scalp ipsilateral to the ligated common carotid artery and by running cold water through the catheter during 2 h of systemic hypoxia. Hypoxia was produced in neonatal rats by breathing 8% oxygen for 2 h in a 37°C chamber. Animals underwent focal cooling with ipsilateral scalp temperatures ranging from 22°C to 35°C. Temperature recordings from the ipsilateral scalp, cerebral hemisphere (dorsal hippocampus) and core (rectal) were obtained. The results suggest that the method is effective in cooling of brain and also to a lesser extent in lowering of the core temperature. At a mean scalp temperature of 28°C, mean hippocampal temperature in hypoxic rat was 29.5°C and mean core temperature in hypoxic rat was 32.8°C. At a lower scalp temperature of 22°C, mean hippocampal temperature in hypoxic rat was 24.7°C and mean core temperature was 31.3°C. Neuropathologic examination 3–4 days following hypoxia-ischemia showed that focal cooling with a scalp temperature of lower than 28°C completely protected from brain damage, and that there was a trend towards greater damage with higher scalp temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293321
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  • 175
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    Distribution of acetylcholinesterase activity in the rat embryonic heart with reference to HNK-1 immunoreactivity in the conduction tissue (1994)
    Springer
    Anatomy and embryology 190 (1994), S. 367-373 
    Details
    ISSN: 1432-0568
    Keywords: Acetylcholinesterase ; HNK-1 ; Heart ; Morphogenesis ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Acetylcholinesterase (AChE) activity was topographically investigated in the presumptive cardiac conduction tissue regions visualized by HNK-1 immunoreactivity in rat embryos, and AChE-positive cells were examined with the electron microscope. On embryonic day (ED) 14.5, when HNK-1 was most intensely visualized, AChE activity could not be detected enzyme-histochemically in the conduction tissue regions, except in the ventricular trabeculae and part of the AV node. On ED 16.5, however, the AChE activity was clearly demonstrated in some parts of the developing conduction tissue. One exception was the AV node region, where an AChE-positive area was in close proximity to an area showing HNK-1 immunoreactivity but did not overlap. Furthermore, AChE activity was demonstrated predominantly in the ventricular trabeculae, including cardiac myocytes, but was rather weak in the atrium. With the electron microscope, AChE reaction products were observed predominantly intracellulary in both developing conduction tissue cells and developing ordinary myocytes, and no reactivity was found in neuronal components. From ED 18.5 until birth, both AChE activity and HNK-1 immunoreactivity faded away in the conduction tissue. Thus, transient AChE activity in the embryonic heart seems to be different from the developing adult form and may be related to a morphogenetic function in embryonic tissues, as proposed by other authors.
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    URL: http://dx.doi.org/10.1007/BF00187294
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  • 176
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    Post-traumatic brain hypothermia reduces histopathological damage following concussive brain injury in the rat (1994)
    Springer
    Acta neuropathologica 87 (1994), S. 250-258 
    Details
    ISSN: 1432-0533
    Keywords: Traumatic brain injury ; Hypothermia Histopathology ; Fluid percussion ; Rat ; Contusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purposes of this study were (1) to document the histopathological consequences of moderate traumatic brain injury (TBI) in anesthetized Sprague-Dawley rats, and (2) to determine whether posttraumatic brain hypothermia (30°C) would protect histopathologically. Twenty-four hours prior to TBI, the fluid percussion interface was positioned over the right cerebral cortex. On the 2nd day, fasted rats were anesthetized with 70% nitrous oxide, 1% halothane, and 30% oxygen. Under controlled physiological conditions and normothermic brain temperature (37.5°C), rats were injured with a fluid percussion pulse ranging from 1.7 to 2.2 atmospheres. In one group, brain temperature was maintained at normothermic levels for 3 h after injury. In a second group, brain temperature was reduced to 30°C at 5 min post-trauma and maintained for 3 h. Three days after TBI, brains were perfusion-fixed for routine histopathological analysis. In the normothermic group, damage at the site of impact was seen in only one of nine rats. In contrast, all normothermic animals displayed necrotic neurons within ipsilateral cortical regions lateral and remote from the impact site. Intracerebral hemorrhagic contusions were present in all rats at the gray-white interface underlying the injured cortical areas. Selective neuronal necrosis was also present within the CA3 and CA4 hippocampal subsectors and thalamus. Post-traumatic brain hypothermia significantly reduced the overall sum of necrotic cortical neurons (519±122 vs 952±130, mean ±SE, P=0.03, Kruskal-Wallis test) as well as contusion volume (0.50±0.14 vs 2.14±0.71 mm3, P=0.004). These data document a consistent pattern of histopathological vulnerability following normothermic TBI and demonstrate hypothermic protection in the post-traumatic setting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296740
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  • 177
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    Postnatal development of neuropeptide Y- and calcitonin gene-related peptide-immunoreactive nerves in the rat urinary bladder (1994)
    Springer
    Anatomy and embryology 189 (1994), S. 361-373 
    Details
    ISSN: 1432-0568
    Keywords: Postnatal development ; Neuropeptide Y ; Calcitonin gene-related peptide ; Urinary bladder ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The postnatal development of neuropeptide Y- and calcitonin gene-related peptide-immunoreactive (NPY-IR and CGRP-IR) nerve fibers in the rat urinary bladder was investigated using whole-mount preparations and cryostat sections. In newborn and 3-day-old rats, many NPY-IR nerve fibers were observed in the subserous and muscle layers. Many NPY-IR nerve cell bodies clustered at branching points of the subserous nerve bundles. Within 4 weeks after birth, these cell bodies drastically decreased in number and spread along the bundles, although the number of NPY-IR nerve fibers increased moderately. In contrast, CGRP-IR nerve fibers in newborn and 3-day-old rats were less developed, and no CGRP-IR nerve cell body was observed in any rat. However, CGRP-IR nerve fiber distribution in the urinary tissues conspicuously increased within 4 weeks after birth. Especially, an increase of the infraepithelial fibers showing a meshwork appearance was prominent in the fundus and corpus of the bladder. The infra- and intraepithelial CGRP-IR nerve meshwork of the ventral wall was more dense than that of the trigone. At 4 weeks, NPY-IR and CGRP-IR nerves were similar to those of the adult rat (8–12 weeks old). The present study suggests a correlation between the development of the peripheral nervous system in the urinary bladder and maturation of micturition behavior in the rat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00190591
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  • 178
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    Fiber composition of the lateral plantar and superficial peroneal nerves in the rat foot (1994)
    Springer
    Anatomy and embryology 189 (1994), S. 393-399 
    Details
    ISSN: 1432-0568
    Keywords: Rat ; Myelinated axons ; C-fibers ; Skin ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study examines the fiber composition of two nerves projecting to the rat hindpaw: the lateral plantar nerve (LPN), which innervates plantar glabrous skin and some plantar muscles, and the foot branch of the superficial peroneal nerve (fSPN), which projects to dorsal hairy skin. The LPN contains 872 (33%) myelinated axons with a size range of 1–7 μm and a peak at 4 μm. Some 200 of the myelinated axons are muscle efferents. There are 1,969 (67%) C-fibers. After neonatal capsaicin treatment, the number of C-fibers in the LPN is 61% below the normal level, but it is not significantly different from control levels after chemical sympathectomy with guanethidine. The fSPN is composed of 470 (20%) myelinated axons with a size range similar to that in the LPN. Virtually all myelinated fibers are sensory. There are 1,791 (80%) C-fibers. In neonatally capsaicin-treated animals, the occurrence of C-fibers is 65% below control levels. In chemically sympathectomized animals, the number of C-fibers in the fSPN is normal. This description of the fiber composition of the LPN and the fSPN in the rat provides a basis for future experimental studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185434
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  • 179
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    Permanent increase of immunocytochemical reactivity for γ-aminobutyric acid (GABA), glutamic acid decarboxylase, mitochondrial enzymes, and glial fibrillary acidic protein in rat cerebral cortex damaged by early postnatal hypoxia-ischemia (1994)
    Springer
    Acta neuropathologica 87 (1994), S. 612-627 
    Details
    ISSN: 1432-0533
    Keywords: Hypoxia-ischemia ; Rat ; Perinatology ; Cerebral cortex ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A former study indicated that hypoxicischemic encephalopathy in rat sustained during early postnatal life may result in permanent epileptic activity in the baseline electroencephalogram. We, therefore, investigated whether the presumed higher firing frequency and metabolic activity of neurons in such hypoxia-damaged cortical areas would be reflected by an enhanced light microscopic immunoreactivity of γ-aminobutyric acid (GABA), the two isoforms of glutamic acid decarboxylase (GAD67 and GAD65), the mitochondrial enzymes cytochrome c oxidase and ATP synthase, and/or glial fibrillary acidic, protein (GFAP). To that end rat pups, 12–13 days of age, were unilaterally exposed to hypoxic-ischemic conditions and, after a survival period of 2 and 61/2 months, respectively, killed by perfusion fixation. After dissection of the brain, coronal vibratome sections of animals showing cortical damage were immunostained for the presence of the abovementioned antigens. Subsequent qualitative analysis revealed that the surroundings of cortical infarctions were unambiguously characterized by a disordered neural network containing numerous nerve cells, fibers and/or endings showing an enhanced immunoreactivity for GABA, both isoforms of glutamic acid decarboxylase, and cytochrome c oxidase and ATP synthase, while the astrocytes showed an enhanced immunoreactivity for GFAP. The diverse patterns of enhanced immunoreactivity suggested, furthermore, a wider low-to-high range of metabolic activities in both excitatory and inhibitory neurons.
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    URL: http://dx.doi.org/10.1007/BF00293323
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  • 180
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    Parcellation of cortical areas by in situ hybridization for somatostatin mRNA in the adult rat: frontal, parietal, occipital, and temporal regions (1994)
    Springer
    Anatomy and embryology 190 (1994), S. 389-398 
    Details
    ISSN: 1432-0568
    Keywords: Neuropeptides ; Visual cortex ; Somatosensory cortex ; Auditory cortex ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The expression of somatostatin mRNA within the neocortex of the rat was examined by in situ hybridization with an alkaline phosphatase-labeled probe. We sought to determine whether parcellation of the neocortex could be based upon the number and laminar location of the hybridized cells. Our investigation demonstrated that the boundaries of the neocortical areas can be determined by the distribution pattern of neurons expressing somatostatin mRNA. Few hybridized cells were located within layer IV, and this sparsity of cells within their wide granular layer marked the primary sensory areas. The occipital region was stratified, with insensely labeled cells in layers II/III and VI and faintly labeled cells in layer V. The parietal region carried a similar stratification, but more space between intensely labeled cells in layers III and V and between layers V and VI gave the region a three-tiered appearance. The temporal region displayed intensely labeled cells dispersed throughout layers III and VI and many in layer V as well as those faintly labeled without any breaks between the laminae. The distribution of the cells hybridized for somatostatin mRNA formed two configurations within the frontal region. It was difficult to identify any lamination in the first area, whereas the second area demonstrated a stratification reminiscent of the parietal region, but with only two tiers. The conclusion of the investigation is that in situ hybridization for somatostatin mRNA provides an exceptional means by which the areal boundaries within the neocortex may be drawn.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00187297
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  • 181
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    Renal eicosanoids and blood pressure in genetically hypertensive rats of the lyon strain (1994)
    Springer
    Journal of biomedical science 1 (1994), S. 201-203 
    Details
    ISSN: 1423-0127
    Keywords: Hypertension ; Eicosanoid ; Rat ; Genetics ; Kidney
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The present paper reviews the evidence for a possible involvement of renal eicosanoids in the pathophysiology of high blood pressure in genetically hypertensive rats of the Lyon strain. Both in vivo and in vitro experiments suggest that an increased ability to synthesize the vasoconstrictor prostaglandin H2 and/or thromboxane A2 in renal vessels (1) acts as an autocrine amplifier of pressor agents and (2) may contribute to resetting the pressure natriuresis curve which is a prerequisite for the development and maintenance of hypertension.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02253302
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  • 182
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    Effects of flezelastine and its enantiomers on LPS-induced IL-1β generationin vitro and LPS-induced pyrexiain vivo (1994)
    Springer
    Inflammation research 41 (1994), S. 99-100 
    Details
    ISSN: 1420-908X
    Keywords: Lipopolysaccharide ; Interleukin 13 ; Pyrexia ; Flezelastine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of the novel antiasthmatic/antiallergic compound flezelastine on LPS-induced actions were investigatedin vitro andin vivo. In monocytes, IL-1β generation stimulated by LPS was inhibited dose dependently.In vivo, LPS-induced fever in rats, which is at least partly driven by the release of IL-1β, was also inhibited by flezelastine. These findings suggest that flezelastine inhibits IL-1 synthesis and/or releasein vitro andin vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01986405
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  • 183
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    Noninvasive loading of the rat ulna in vivo induces a strain-related modeling response uncomplicated by trauma or periostal pressure (1994)
    Springer
    Calcified tissue international 54 (1994), S. 241-247 
    Details
    ISSN: 1432-0827
    Keywords: Loading ; Strain ; Modeling ; Rat ; Ulna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Adaptive changes in bone modeling in response to noninvasive, cyclic axial loading of the rat ulna were compared with those using 4-point bending of the tibia. Twenty cycles daily of 4-point bending for 10 days were applied to rat tibiae through loading points 23 and 11 mm apart. Control bones received nonbending loads through loading points 11 mm apart. As woven bone was produced in both situations, any strain-related response was confounded by the response to direct periosteal pressure. Four-point bending is not, therefore, an ideal mode of loading for the investigation of strain-related adaptive modeling. The ulna's adaptive response to daily axial loading over 9 days was investigated in 30 rats. Groups 1–3 were loaded for 1200 cycles: Group 1 at 10 Hz and 20 N, Group 2 at 10 Hz and 15 N, and Group 3 at 20 Hz and 15 N. Groups 4 and 5 received 12,000 cycles of 20 N and 15 N at 10 Hz. Groups 1 and 4 showed a similar amount of new bone formation. Group 4 showed the same pattern of response but in reduced amount. The responses in Groups 2 and 3 were either small or absent. Strains were measured with single-element, miniature strain gauges bonded around the circumference of dissected bones. The 20 N loading induced peak strains of 3500–4500 μstrain. The width of the periosteal new bone response was proportional to the longitudinal strain at each point around the bone's circumference. It appears that when a bone is loaded in a normal strain distribution, an osteogenic response occurs when peak physiological strains are exceeded. In this situation the amount of new bone formed at each location is proportional to the local surface strain. Cycle numbers between 1200 and 12,000, and cycle frequencies between 10 and 20 Hz have no effect on the bone's adaptive response.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301686
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  • 184
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    Effect of running exercise on the bone loss induced by orchidectomy in the rat (1994)
    Springer
    Calcified tissue international 55 (1994), S. 33-37 
    Details
    ISSN: 1432-0827
    Keywords: Osteoporosis ; Rat ; Orchidectomy ; Exercise ; Strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effect of exercise on castration-induced osteoporosis in 3-month-old male rats weighing 264±4 g at the beginning of the experiment was studied. A testosterone deficiency was induced by orchidectomy (ORC), and the exercise group ran 10 m/minute for 1 hour a day on a treadmill at 0% grade. There were seven groups of eight rats (n=56) randomized into a control group killed at time 0, and sham, ORC and ORC and exercise groups killed at 4 and 8 weeks. ORC reduced body weight gain (with analysis of variance (ANOVA) P〈0.001), and at 4 weeks the body weight was 343±14 g in ORC group and 301±4 g in the ORC and exercise group (P〈0.01). The increase in femoral length was slower in the ORC+exercise groups. The ash weight of the tibia did not decrease significantly after ORC or ORC+ exercise. ORC did not affect 45Ca incorporation, but exercise slightly increased it in the whole tibia 8 weeks after ORC (with ANOVA P=0.057). ORC had significantly lowered the trabecular bone volume in the secondary spongiosa of the distal femur at 4 and 8 weeks, and exercise did not prevent this. This is an opposite finding to our previous study with ovariectomized female rats [12]. ORC also significantly had reduced the osteoblast-lined trabecular bone surface and the number of osteoclasts by 8 weeks after the operation. Exercise increased the osteoblast-lined surface and the number of osteoclasts. The mechanical strength of the femoral neck also was reduced after ORC and this was not prevented by exercise either. In conclusion, ORC reduces bone growth and turnover which leads to osteopenia in growing rats. Moderate treadmill exercise does not reverse the ORC-induced loss of trabecular bone and the reduced mechanical strength of the femoral neck, although it has a positive effect on the osteoblast and osteoclast indices and on calcium incorporation into bone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310166
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  • 185
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    Daunorubicin and daunorubicinol pharmacokinetics in plasma and tissues in the rat (1994)
    Springer
    Cancer chemotherapy and pharmacology 35 (1994), S. 213-218 
    Details
    ISSN: 1432-0843
    Keywords: Key words Anthracyclines ; Daunorubicin ; Daunorubicinol ; Pharmacokinetics ; Rat ; Tissue concentrations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Recent evidence suggests that 13-hydroxy metabolites of anthracyclines may contribute to cardiotoxicity. This study was designed to determine the pharmacokinetics of daunorubicin and the 13-hydroxy metabolite daunorubicinol in plasma and tissues, including the heart. Fisher 344 rats received 5 mg kg–1 daunorubicin i.v. by bolus injection. Rats were killed at selected intervals for up to 1 week after daunorubicin administration for determination of concentrations of daunorubicin and daunorubicinol in the plasma, heart, liver, kidney, lung, and skeletal muscle. Peak concentrations of daunorubicin were higher than those of daunorubicinol in the plasma (133 ± 7 versus 36 ± 2 ng ml–1; P 〈 0.05), heart (15.2 ± 1.4 versus 3.4 ± 0.4 μg g–1; P 〈 0.05), and other tissues. However, the apparent elimination half-life of daunorubicinol was longer than that of daunorubicin in most tissues, including the plasma (23.1 versus 14.5 h) and heart (38.5 versus 19.3 h). In addition, areas under the concentration/time curves (AUC∞) obtained for daunorubicinol exceeded those found for daunorubicin in almost all tissues, with the ratios being 1.9 in plasma and 1.7 in the heart. The ratio of daunorubicinol to daunorubicin concentrations increased dramatically with time from 〈1 at up to 1 h to 87 at 168 h in cardiac tissue. Thus, following daunorubicin injection, cumulative exposure (AUC∞) to daunorubicinol was greater than that to daunorubicin in the plasma and heart. If daunorubicinol has equivalent or greater potency than daunorubicin in causing impairment of myocardial function, it may make an important contribution to the pathogenesis of cardiotoxicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00686550
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  • 186
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    The in vivo effect of a new, in vitro, extremely potent vitamin D3 analog KH1060 on the suppression of renal allograft rejection in the rat (1994)
    Springer
    Calcified tissue international 54 (1994), S. 150-154 
    Details
    ISSN: 1432-0827
    Keywords: Vitamin D analog ; KH1060 ; Kidney transplantation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract KH1060 is a new 20-epi-vitamin D3 analog, which has exerted a considerable immunosuppressive potency in vitro. We have tested in vivo the effect of KH1060 on the suppression of renal allograft rejection in the rat. Allogenic kidney transplantation from DA donor rats to Lewis recipient rats treated intraperitoneally with KH1060 in doses from 0.2 to 6 μg/kg/day, or saline (placebo group), or CyA 10 mg/kg/day for 10 days (positive control group), was performed. Median graft survival time in KH1060-treated groups was 7–9 days, in the placebo group 6 days, whereas CyA led to long-term graft survival, 34 days in 50% of rats and 〉100 days in 50% of rats. In vivo, KH1060 failed to prolong renal allograft survival considerably, and led to development of hypercalcemia. Our results stress the existence of a large discrepancy between the in vitro and in vivo immunoregulatory effects of this vitamin D analog.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296066
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  • 187
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    Effect of 1α-vitamin D3 on bone strength and composition in growing rats with and without corticosteroid treatment (1994)
    Springer
    Calcified tissue international 55 (1994), S. 443-450 
    Details
    ISSN: 1432-0827
    Keywords: Bone mechanics ; Bone composition ; Vitamin D3 ; Corticosteroid ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effects of 1α-vitamin D3 were studied for 6 months in 2-month-old male and female rats on a moderately low calcium diet with or without low-dose prednisolone treatment. Both cortical bone mechanical and biochemical properties were examined. Femoral bone specimens were subjected to torsional loading tests. With age, bone strength and stiffness increased in both sexes, accompanied by an increased degree of mineralization (bone ash and calcium concentrations). During growth, strength and stiffness increased more in male than in female rats. When 1α-vitamin D3 (0.5 μg/kg/day) was given alone, bone mechanical competence improved significantly whereas insulin-like growth factor-I (IGF-I) and calcium concentrations in the bone matrix were significantly reduced. Treatment with low-dose prednisolone (0.5 mg/kg/day) alone did not influence bone mechanical properties compared with intact control rats (without prednisolone) although a significant reduction in calcium concentration and an increased phosphorus concentration were measured. A combined therapy with prednisolone and 1α-vitamin D3 significantly increased bone strength, toughness, and stiffness compared with control bones. Both mineralization degree (ash and calcium concentration) and IGF-I concentration were decreased. We conclude that (1) mechanical properties of rat cortical bones improve relatively more in males compared with agematched females during growth which is related to increased bone mass and size, (2) low-dose prednisolone treatment does not change mechanical properties in males, and altered them only nonsignificantly in females despite a change in mineralization degree in both sexes; (3) treatment with 1α-vitamin D3 results in a consistent increase in mechanical competence of the bone accompanied by a significant decrease in IGF-I concentration in the bone matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298558
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  • 188
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    Quantitative distribution of rat brain monoamine oxidase A by [14C]clorgyline autoradiography (1994)
    Springer
    Experimental brain research 99 (1994), S. 375-382 
    Details
    ISSN: 1432-1106
    Keywords: Monoamine oxidase A ; Clorgyline ; Quantitative autoradiography ; Brain ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The distribution of functionally active monoamine oxidase type A (MAO-A) was investigated by in vivo quantitative autoradiography using [14C]clorgyline in normal, conscious rat brain. [14C]clorgyline was synthesized by the methylation reaction of N-desmethylclorgyline using [14C]methyliodide. Sixty minutes after [14C]clorgyline administration (1.58 MBq/animal i.v.), the brains were removed and prepared for autoradiography by washing the brain sections with 5% trichloroacetic acid solution to remove the nonbinding free tracer. The amount of MAO-A was calculated from the regional acid-insoluble tissue radioactivity and the specific activity of the tracer. The highest amount of MAO-A (5.84 nmol/g tissue) was found in the locus coeruleus. The interpeduncular nucleus, habenular nucleus, fasciculus retroflexus, and solitary tract nucleus possessed over 1.6 nmol/g tissue of MAO-A. Among 23 regions of interest, the lowest amount of MAO-A (0.37 nmol/g tissue) was found in the globus pallidus. The findings of this study suggest that the pattern of MAO-A parallels both in neuroanatomical distribution and in density that of norepinephrine and serotonin innervation. The MAO-A concentration was, however, relatively low in the dopamine-related areas. This corresponded to the previous results obtained by histochemical analysis. In addition, among the white matter structures, a high amount of MAO-A was found specifically in the fasciculus retroflexus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228974
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  • 189
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    Decrease of extracellular catecholamine content in the vicinity of cortical penicillin-induced epileptogenic focus: voltammetric study in the rat (1994)
    Springer
    Experimental brain research 98 (1994), S. 97-100 
    Details
    ISSN: 1432-1106
    Keywords: Epileptogenic cortical focus ; Catecholamines ; Voltammetry ; Penicillin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Differential pulse voltammetry with carbonfibre microelectrodes was used in chloralhydrate-anaesthetized rats to test the influence of the penicillin-G-Na (PNC)-induced (topical application, approximately 2000 IU) epileptic activity on the catecholamine content (catechol-oxidative current, CA.OC) in the parietal cortex. In the experimental group (n = 4) after PNC a nonlinear CA.OC lowering was observed; this decrease during the first 10 min was faster than in the control group (n = 4). Significantly different values were observed from the 4th min after application. The best fit for this experimental curve gave the logarithmic function (f(t) = a + b.ln(t), a =105.8, b= -10.6) with regression coefficient r = 0.98. From the 12th min after PNC application until the end of the experiments (54th min) CA.OC values ranged from 78% to 84% of the control group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229113
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  • 190
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    Decreased cerebrospinal fluid flow through the central canal of the spinal cord of rats immunologically deprived of Reissner's fibre (1994)
    Springer
    Experimental brain research 98 (1994), S. 431-440 
    Details
    ISSN: 1432-1106
    Keywords: Subcommissural organ ; Reissner's fibre ; Immunological blockade ; Cerebrospinal fluid circulation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The subcommissural organ is an ependymal brain gland that secretes glycoproteins to the cerebrospinal fluid (CSF) of the thrid ventricle. They condense to form a fibre, Reissner's fibre (RF), that runs along the aqueduct and fourth ventricle and the central canal of the spinal cord. A single injection of an antibody against the secretory glycoproteins of RF into a lateral ventricle of adult rats results in animals permanently deprived of RF in the central canal and bearing a “short” RF extending only along the aqueduct and the fourth ventricle. These animals, together with untreated control animals were used to investigate the probable influence of RF in the circulation of CSF in the central canal of the spinal cord. For this purpose, two tracers (horseradish peroxidase and rabbit immunoglobulin) were injected into the ventricular CSF. The animals were killed 13, 20, 60, 120 and 240 min after the injection, and the amount of the tracers was estimated in tissue sections obtained at proximal, medial and distal levels of the spinal cord. In rats deprived of RF, a significant decrease in the amount of tracers present in the central canal was observed at all experimental intervals, being more evident at 20 min after the injection of the tracers. This suggests that lacking a RF in the central canal decreases the bulk flow of CSF along the central canal. Turbulences of the CSF at the entrance of the central canal of RF-deprived rats might explain the inability of the regenerating RF to progress along the central canal, as well as the reduced flow of CSF in the central canal of these animals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233981
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  • 191
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    Membrane ionic currents and properties of freshly dissociated rat brainstem neurons (1994)
    Springer
    Experimental brain research 79 (1994), S. 407-420 
    Details
    ISSN: 1432-1106
    Keywords: Ion channels ; Patch clamp ; Hypoglossal ; Vagus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It is well known that neuronal firing properties are determined by synaptic inputs and inherent membrane functions such as specific ionic currents. To characterize the ionic currents of brainstem cardio-respiratory neurons, cells from the hypoglossal (XII) nucleus and the dorsal motor nucleus of the vagus (DMX) were freshly dissociated and membrane ionic currents were studied under whole-cell voltage and current clamp. Both of these neurons showed a TTX-sensitive Na+ current with a much larger current density in XII than DMX neurons. This Na+ current had two (fast and slow) distinct inactivation decay components. The ratio of the magnitudes of the fast to slow component was roughly two-fold greater in DMX than in XII cells. Both DMX and XII neurons also showed a high voltage-activated Ca2+ current, but this current density was significantly greater (three-fold) in DMX than XII neurons. A relatively small amount of low-voltage activated Ca2+ current was also observed in DMX neurons, but not in the majority of XII cells. A transient and a sustained outward current components were observed in DMX cells, but only sustained currents were present in XII neurons. These outward currents had a reversal potential of about -70 mV with 3 mM external K+ and -30mV with 25 mM K+, and substitution of K+ with cesium and tetraethylammonium suppressed more than 90% the outward currents, indicating that most outward currents were carried by K+. The transient outward current consisted of two components with one sensitive to 4-aminopyridine and the other to intracellular Ca2+. In XII neurons, BRL 38227 (lemakalim), an ATP-sensitive K+ (KATP) channel activator, increased the sustained K+ currents by 10% of control, and glibenclamide, a KATP channel blocker, decreased the sustained K+ currents by 20%. Evidence for the presence of an inward rectifier K+ current was also obtained from both XII and DMX neurons. These results on XII and DMX neurons indicate that (1) the methods used to dissociate neurons provide a useful means to overcome voltage clamp technical difficulties; (2) ion channel characteristics such as density and biophysical properties of DMX neurons are very different from those of XII neurons; and (3) several newly discovered membrane ionic currents are present in these cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229181
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  • 192
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    Hyperthermia aggravates and hypothermia ameliorates epileptic brain damage (1994)
    Springer
    Experimental brain research 99 (1994), S. 43-55 
    Details
    ISSN: 1432-1106
    Keywords: Status epilepticus ; Brain damage Hypothermia ; Hyperthermia ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The influence of hyperthermia and hypothermia on epileptic brain damage was studied in rats, in which status epilepticus was induced by flurothyl. Histopathological changes were examined by light microscopy after 1 or 7 days of recovery. Two series of animals were studied. In the first, short periods of seizures (20 and 25 min) were employed to examine whether moderate hyperthermia (39.5° C) would aggravate epileptic brain damage, and a longer period (45 min) was used to investigate whether moderate hypothermia (32.5° C) would ameliorate the damage. The second series investigated whether brief periods of status epilepticus (10 min) would cause brain damage if hyperthermia were high or excessive. For this series, animals with body temperatures of 37.0, 39.0, and 41.0° C were studied. Data from normothermic animals (37.5° C) confirmed previously described neuronal damage. Although hyperthermic animals failed to showe increased damage in the CA1 sector, or in the hilar region of the dentate gyrus, they showed enhanced damage in the neocortex and globus pallidus (GP). In substantia nigra pars reticulata (SNPR) four out of five hyperthermic animals had bilateral infarcts after 20 min of status epilepticus, whereas no normothermic animal showed such damage. Hypothermia seemed to ameliorate epileptic brain damage in the neocortex (n.s.) and GP (P 〈 0.05) following status epilepticus for 45 min. Three out of seven hypothermic animals had mild SNPR involvement compared to severe infarction of the nucleus in five out of six normothermic animals (P 〈 0.05). Thus, hyperthermia aggravated and hypothermia ameliorated epileptic brain damage both in regions showing selective neuronal necrosis (neocortex) and in regions developing pan-necrosis (GP and SNPR). The second series displayed an unexpected result of excessive hyperthermia. Animals subjected to only 10 min of status epilepticus at a temperature of 41° C showed not only neocortical lesions, but also moderate to extensive damage to the hippocampus (CA1, subiculum, and dentate gyrus). It is concluded that at high body and brain temperature, brief periods of status epilepticus can yield extensive brain damage, primarily affecting the hippocampus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241411
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    Quantitative analysis of GABA-like-immunoreactive and parvalbumin-containing neurons in the CA1 region of the rat hippocampus using a stereological method, the disector (1994)
    Springer
    Experimental brain research 99 (1994), S. 267-276 
    Details
    ISSN: 1432-1106
    Keywords: GABA ; Calcium-binding protein Hippocampus ; Disector ; Immunocytochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The numerical density of neurons in the CA1 region of the rat dorsal hippocampus has been estimated by a stereological method, the disector, using pairs of video images of toluidine blue-stained, plastic-embedded, 0.5-μm-thick sections, 3 μm distant from each other. The chemical properties of those disector-counted cells were further analyzed by postembedding immunocytochemical methods on adjacent, semithin sections using antibodies against gamma-aminobutyric acid (GABA) and a specific calcium-binding protein, parvalbumin (PV). The density of neurons in the CA1 region was 35.2 × 103/mm3; numerical densities in the stratum oriens (SO), stratum pyramidale (SP), and strata radiatum-lacunosum-moleculare (SRLM) were 11.3 × 103/mm3, 272.4 × 103/mm3, and 1.9 × 103/mm3, respectively. The numerical densities of GABA-like immunoreactive (GABA-LIR) and PV-immunoreactive (PV-IR) neurons were 2.1 × 103/mm3 and 1.1 × 103/mm3, respectively, which were 5.8% and 3.2% of all neurons, respectively. In the CA1 region only about 60% of PV-positive neurons were GABA-LIR. However, taking the previous observation into consideration that almost all hippocampal PV-positive neurons were immunoreactive for the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD), neurons that were immunoreactive to either GABA or PV or both (GABA+ and/or PV + neurons) were regarded as a better representative of GABAergic neurons in this region; thus, the numerical density of these GABA + and/or PV + neurons was 2.5 × 103/mm3 and they were 7.0% of all neurons in the CA1 region. Lamellar analysis showed that the numerical densities of GABA+ and/or PV+, GABA-LIR, and PV-IR neurons were highest in the SP, where they were 8.2 × 103/mm3, 6.2 × 103/mm3, and 5.4 × 103/mm3, respectively. The results of the present study indicate that the proportions of GABAergic neurons and a subpopulation of them, PV-containing GABAergic neurons, to other presumable non-GABAergic neurons are far smaller in the CA1 region of the hippocampus than in several neocortical regions previously reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239593
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  • 194
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    Central respiratory neuronal activity after axonal regeneration within blind-ended peripheral nerve grafts: time course of recovery and loss of functional neurons (1994)
    Springer
    Experimental brain research 98 (1994), S. 238-244 
    Details
    ISSN: 1432-1106
    Keywords: Peripheral nerve autograft ; Respiratory neurons ; Axonal regeneration ; Medulla oblongata ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Autologous segments of peroneal nerve were implanted into the medulla of adult rats to induce axonal regeneration of central neurons axotomised during the grafting procedure. Grafts were inserted in the midline where respiratory axons decussate or laterally, either in the nucleus tractus solitarius or in the nucleus ambiguus, close to respiratory cell bodies. The distal part of each graft was left unconnected (blind-ended graft). Between 2 and 30 months post-implantation, unit recordings from single fibres were made from small strands teased from the grafts to investigate activity of neurons regenerating axons. Spontaneous respiratory and non-respiratory activity was present only in grafts examined between 2 and 6 months post-implantation. Respiratory units had discharge patterns identical to those of normal inspiratory or expiratory neurons; their responses to lung inflation and asphyxia were also similar to those of central respiratory neurons. No spontaneous activity was present in the grafts examined 7–30 months post-implantation. Moreover, asphyxia, which normally enhances the activity of central respiratory neurons, failed to elicit activity. These results were similar in all grafts, regardless of the site of implantation. The presence of spontaneous activity only between 2 and 6 months post-implantation indicates that once axonal growth of respiratory neurons is stopped within blind-ended grafts, those neurons still exhibited normal functional properties for 3 months. The absence of activity 6 months after grafting suggests that loss of functional regenerating respiratory neurons does not occur progressively and follows an “all or nothing” rule within blind-ended grafts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228412
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  • 195
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    Microglial and astroglial reactions to anterograde axonal degeneration: a histochemical and immunocytochemical study of the adult rat fascia dentata after entorhinal perforant path lesions (1994)
    Springer
    Experimental brain research 98 (1994), S. 245-260 
    Details
    ISSN: 1432-1106
    Keywords: Hippocampus ; Synaptic plasticity ; Glial cells ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The reaction of microglial and a stroglial cells to anterograde axonal degeneration was studied in the fascia dentata of adult rats at various timepoints after removal of the entorhinal perforant path projection. Microglial cells were identified by histochemical staining for nucleoside diphosphatase (NDPase) at light and electron microscopical levels. Astroglial cells were stained immunocytochemically for glial fibrillary acidic protein (GFAP). Activated astroglial cells and some microglial cells also stained immunocytochemically for the intermediate filament protein vimentin. Phagocytotic activity was detected by histochemical staining for acid phosphatase. The postlesional connective reorganization of the cholinergic septohippocampal projection was monitored by histochemical staining for acetyl cholinesterase. Twenty-four hours after entorhinal cortex ablation, microglial cells in the perforant path zones of the fascia dentata and the adjacent neuropil reacted by shortening and coarsening of processes and an increase in NDPase reactivity. These changes occurred prior to a noticeable increase in GFAP immunoreactivity and hypertrophy of astroglial cells (first evident on postlesional day 2) or sprouting of cholinergic septohippocampal fibres (first evident on day 3). There was evidence of an early, local proliferation of microglial cells in the denervated perforant path zones and migration into these zones of microglial cells from adjacent intact areas. The specific accumulation of strongly stained microglial cells within the denervated parts of the dentate molecular layer persisted for at least 4 weeks, while the astroglial reaction subsided at 3 weeks. The results demonstrate an early activation of microglial cells by axonal degeneration, and indicate that these cells may play a pivotal, inductive role in the subsequent glial and neural events.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228413
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  • 196
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    Fos protein induction, neuropathology, and pharmacological protection after excitotoxic brain insult (1994)
    Springer
    Experimental brain research 98 (1994), S. 421-430 
    Details
    ISSN: 1432-1106
    Keywords: Fos protein induction ; Neuropathology ; Kainic acid ; N-Methyl d-aspartate Pharmacological protection ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The excitotoxins kainic acid and N-methyl d-aspartate (NMDA) were unilaterally injected in the rat striatum. Kainic acid injections resulted in a widespread pattern of Fos protein induction, mainly involving cortical olfactory structures and hippocampus. Immunoreactive cells were observed in large number 2–24 h after injection and had almost completely disappeared by 48 h. NMDA injections elicited a shorter (2–8 h) expression of Fos protein, involving a lower number of cells in cortical olfactory structures, a much larger number of cells in the other cortical regions, and not involving the hippocampus at all. Characteristically none of the two excitotoxins stimulated Fos expression from striatal neurons, even in the close vicinity of the needle tract. In addition to striatal lesions almost equivalent in size, the two excitotoxins caused distant lesions of different extension: kainic acid resulted in extensive neuronal degeneration in the olfactory-entorhinal cortices and among pyramidal neurons of the hippocampus; NMDA caused a less widespread neurodegeneration, restricted to the olfactory cortex. Administration of the competitive NMDA antagonist CGP 39551 largely prevented the distant, but not the local, neuropathological changes caused by intrastriatal kainic acid or NMDA. The expression of Fos protein, however, was partially prevented only in NMDA cases. The present results show a good relationship between the spreading of circuit overexcitation caused by the two excitotoxins and the regional and temporal patterns of Fos expression. The relationship between Fos expression and neuropathological condition remains, however, elusive.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233980
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  • 197
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    An iontophoretic study of the effects of α-amino-hydroxy-5-methyl-4-isoxazole propionic acid lesions of the nucleus basalis magnocellularis on cholinergic and GABAergic influences on frontal cortex neurones of rats (1994)
    Springer
    Experimental brain research 98 (1994), S. 441-456 
    Details
    ISSN: 1432-1106
    Keywords: α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid lesion ; Cholinergic ; GABAergic ; Nucleus basalis ; Iontophoresis ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Unilateral lesions of the nucleus basalis magnocellularis (NBM) produced by α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid in rats caused, 8–10 weeks after the lesion, a 94% reduction in cortical acetylcholinesterase fibres and reduced activities of acetylcholinesterase and choline acetyltransferase by 70–80% in the frontal cortex ipsilateral to the lesion. In anaesthetized unlesioned control rats, iontophoretic administration of acetylcholine and carbachol produced atropine-sensitive inhibition and excitation of frontal cortical neurones, effects similar to those produced by electrically stimulating the NBM. The lesion reduced cortical neuronal firing rates but increased the percentage and sensitivity of neurones responding to acetylcholine, the predominant response changing from inhibition to excitation; response duration increased but latency was unaffected. The size of the response of individual neurones to carbachol, but not the percentage of sensitive neurones, was also increased in lesioned animals. The proportion of neurones responding to bicuculline and their individual sensitivities were increased by the lesion, suggesting that the lesion increased GABAergic tone; responses to glutamate were unchanged. The lesion did not affect the proportion of neurones in which acetylcholine modulated neuronal responses but reversed the nature of the modulation to predominantly excitatory; excitation was the predominant response to electrical forepaw stimulation in unlesioned control animals. This suggests a possible interaction between GABAergic and cholinergic mechanisms in selective attention and processing of cognitive information. Acute administration of di-isopropyl fluorophosphate to unlesioned animals significantly increased the number of frontal cortical neurones responding to acetylcholine, without affecting individual neuronal sensitivity or responses to carbachol and glutamate. The similarity of these effects to those of acetylcholine in lesioned animals suggests that the increased sensitivity to acetylcholine in the latter was due to loss of acetylcholinesterase, enabling diffusion of acetylcholine to more distant neurones. However, acetylcholinesterase does not hydrolyse carbachol and therefore it is necessary to postulate a different post-synaptic mechanism to explain the lesion-induced increases in the sensitivities of individual neurones to carbachol and to acetylcholine; interpretation of experimental findings should take these two mechanisms into account.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233982
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  • 198
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    Effects of naftidrofuryl oxalate on microsphere-induced changes in acetylcholine and amino acid content of rat brain regions (1994)
    Springer
    Experimental brain research 99 (1994), S. 7-16 
    Details
    ISSN: 1432-1106
    Keywords: Acetylcholine ; Asparte ; Brain ischemia Glutamate ; Microsphere embolism Naftidrofuryl oxalate ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Effects of naftidrofuryl oxalate (naftidrofuryl) on neurotransmitter, acetylcholine, and amino acid content of brain regions following microsphere-induced cerebral embolism were examined to elucidate its possible therapeutic effects on ischemic brain. Rats received 900 microspheres (48 μm in diameter) via the right internal carotid artery, followed by ligation of the right common carotid artery; and histological and biochemical alterations were examined on the 3rd, 5th, and 28th days after embolism. The embolism induced increases in triphenyltetrazolium chloride-(TTC)-unstained areas and decreases in acetylcholine, glutamate, aspartate, and γ-aminobutyric acid (GABA) contents in the cerebral cortex, striatum, and hippocampus of the right hemisphere, suggesting that microsphere embolism causes severe damage to these brain regions. Hematoxylin-eosin staining of the right cortical sections after embolism showed degeneration and necrosis of nerve cells with chromatolytic nuclei and eosinophilic cytoplasm. Changes in neurotransmitters of the left hemisphere were relatively small. Treatment with naftidrofuryl of the embolized rats with stroke-like symptoms took place from postoperative day 1 to 28. Treatment resulted in a reduction in TTC-unstained areas, less morphological damage to cerebral cortex on the 3rd and 5th days, and an appreciable restoration of acetylcholine content of three brain regions of the right hemisphere throughout the experiment, but restoration of neurotransmitter amino acids was observed to a smaller degree. The results suggest that naftidrofuryl is capable of preventing the development of ischemia-induced, sustained damage to brain regions vulnerable to oxygen deficiency, particularly by improving impaired acetylcholine metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241407
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  • 199
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    Mapping of the colocalization of calretinin and tyrosine hydroxylase in the rat substantia nigra and ventral tegmental area (1994)
    Springer
    Experimental brain research 99 (1994), S. 34-42 
    Details
    ISSN: 1432-1106
    Keywords: Fluorescence immunohistochemistry Calcium-binding protein ; Dopamine Neuroprotection ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The distribution of calretinin (CR), a calcium binding protein, was compared with that of tyrosine hydroxylase (TH), the rate-limiting enzyme in the synthesis of dopamine, throughout the rostrocaudal extent of the rat subsantia nigra (SN) and ventral tegmental area (VTA). After mapping the cells using double-labelling immunofluorescence, it was possible to distinguish three distinct cell types: cells immunoreactive for CR only, cells immunoreactive for TH only, and cells in which the two proteins were colocalized (CR+TH). Colocalized cells in rat brain sections comprised approximately 40–55% of the fluorescent labelled cells in the SN compacta, 30–40% in the VTA, and 55–80% in the SN lateralis. Colocalized cells in the SN reticulata were infrequent except in the more caudal sections where a majority of the TH-immunoreactive cells also contained CR. The percentage of CR cells that contained TH was approximately 80% in the SN compacta and averaged 65% in the VTA. Overall, the percentage of TH-immunoreactive cells which also contained CR was approximately 50% in the SN compacta and 45% in the VTA. These data reveal a significant degree of colocalization of CR in dopamine-producing cells of the SN and VTA and suggest the need for studies concerning the fate of these individual cell types following experimental manipulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241410
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  • 200
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    Regeneration of dorsal root axons into experimentally altered glial environments in the rat spinal cord (1994)
    Springer
    Experimental brain research 99 (1994), S. 25-33 
    Details
    ISSN: 1432-1106
    Keywords: Regeneration ; Schwann cells Glial environment ; X-Irradiation ; Astrocytes ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Exposure of the lumbar spinal cord of rats to X-rays 3 days after birth results in changes in the composition of central glia. Shortly after irradiation, there is both retardation of central myelin formation and a loss of integrity of the astrocyte-derived glia limitans on the dorsal surface of the cord. Subsequently, Schwann cells invade, undergo division and myelinate axons in the dorsal funiculi in the irradiated region of the cord, creating there an environment similar to that of peripheral nerve. The present study was undertaken to compare the ability of lesioned dorsal root axons to grow back into the altered glial environments that exist within the spinal cord after irradiation. This regrowth was assessed by injecting Fluoro-Gold into the spinal cord and subsequently examining neurons in the dorsal root ganglia (DRG) for the presence of this label. Numbers of retrogradely labeled neurons were counted in the DRG in both injured and contralateral non-injured sides. Non-irradiated control rats had almost no labeled DRG neurons on the injured side, whereas Fluoro-Gold labeled neurons were observed in substantial numbers in the DRG on the injured side of irradiated rats. There was a definite trend in the data, indicating that the longer the interval between irradiation and root injury, the greater the number of labeled neurons. Since the Fluoro-Gold labeling technique does not allow for visualization of the labeled axons within the spinal cord, a few animals were used to assess anterograde labeling with wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP/HRP) from the dorsal root into the spinal cord. HRP-filled regenerating axons were visualized in dorsal white and gray matter of the irradiated spinal cord. Such axons were not present in the non-irradiated spinal cords. Radiation-induced changes in glial populations are discussed, particularly with regard to the temporal sequence of these changes and their possible relationship to the conversion of a normally non-permissive environment into one conducive to axonal regrowth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241409
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