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  • 2000-2004  (64)
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  • 1
    Unknown
    The great American history fact-finder : the who, what, where, when, and why of American history (2004)
    Boston : Houghton Mifflin
    Details
    Keywords: United States, History, Dictionaries ; Electronic books
    Pages: xi, 608 p.
    Edition: 2nd ed., updated and expanded
    ISBN: 1-417-59441-1
    URL: http://www.netLibrary.com/urlapi.asp?action=summary&v=1&bookid=131795
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    E-Book (German National Licenses)
  • 2
    Unknown
    The poetics of appearance in the Attic korai (2004)
    Austin : University of Texas Press
    Details
    Keywords: Acropolis (Athens, Greece) ; Athena (Greek deity), Cult ; Electronic books ; Inscriptions, Greek ; Kore statues ; Polychromy, Greece, Athens ; Votive offerings, Greece, Athens
    Pages: xiv, 230 p., [32] p. of plates
    Edition: 1st ed
    ISBN: 0-292-79763-X
    URL: http://www.netLibrary.com/urlapi.asp?action=summary&v=1&bookid=130430
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    E-Book (German National Licenses)
  • 3
    Unknown
    Sight unseen : an exploration of conscious and unconscious vision (2004)
    Oxford ; New York : Oxford University Press
    Details
    Keywords: Electronic books ; Vision disorders ; Visual perception
    Pages: ix, 135 p.
    ISBN: 1-423-70567-X
    URL: http://www.netLibrary.com/urlapi.asp?action=summary&v=1&bookid=130746
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    E-Book (German National Licenses)
  • 4
    Unknown
    Appraising and using social research in the human services : an introduction for social work and health professionals (2004)
    London ; Philadelphia : Jessica Kingsley Publishers
    Details
    Keywords: Electronic books ; Evaluation research (Social action programs) ; Human services, Research, Methodology ; Social service, Research, Methodology
    Notes: The process of using social research -- Some key issues in appraising social research -- Questionnaire design for quantitative research: structured instruments -- Surveys and sampling -- Experimental and quasi-experimental designs -- The qualitative interview -- Ethnography and practice -- Content analysis: grounded theory -- Qualitative evaluation -- Multimethod research
    Pages: 256 p.
    ISBN: 1-423-71051-7
    URL: http://www.netLibrary.com/urlapi.asp?action=summary&v=1&bookid=129937
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    E-Book (German National Licenses)
  • 5
    Unknown
    Hispanic spaces, Latino places : community and cultural diversity in contemporary America (2004)
    Austin : University of Texas Press
    Details
    Keywords: Electronic books ; Hispanic Americans, Case studies, Social conditions ; Human geography, Case studies, United States
    Notes: Hispanic American legacy, Latino American diaspora / Daniel D. Arreola -- The plaza in Las Vegas, New Mexico: a community gathering place / Jeffrey S. Smith -- Social geography of Laredo, Texas, neighborhoods: distinctiveness and diversity in a majority-Hispanic place / Michael S. Yoder and Renée La Perrière de Gutiérrez -- Barrio under siege: Latino sense of place in San Francisco, California / Brain J. Godfrey -- Globalization of the barrio: transformation of the Latino cultural landscapes of San Diego, California / Lawrence A. Herzog -- Barrio space and place in southeast Los Angeles, California / James R. Curtis -- Changing Latinzation of New York City / Inés M. Miyares -- Soccer and Latino cultural space: metropolitan Washington fútbol leagues / Marie Price and Courtney Whitworth -- The cultural landscape of a Puerto Rican neighborhood in Cleveland, Ohio / Albert Benedict and Robert B. Kent -- Latinos in polynucleated Kansas City / Steven L. Driever -- Se venden aqu:̓ Latino commercial landscapes in Phoenix, Arizona / Alex Oberle -- Hispanics in the American South and the transformation of the poultry industry / William Kandel and Emilio A. Parrado -- Hispanization of Hereford, Texas / Terrence W. Haverluk
    Pages: viii, 334 p.
    Edition: 1st ed
    ISBN: 0-292-79744-3
    URL: http://www.netLibrary.com/urlapi.asp?action=summary&v=1&bookid=130410
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    E-Book (German National Licenses)
  • 6
    Unknown
    The future of the international monetary system (2004)
    Cheltenham, UK ; Northampton, MA : Edward Elgar
    Details
    Keywords: Capital movements ; Debts, External ; Electronic books ; Finance, Developing countries ; Foreign exchange ; International finance ; Monetary policy ; Monetary policy, Developing countries
    Pages: 1 v. (various pagings)
    ISBN: 1-8454-2469-7
    URL: http://www.netLibrary.com/urlapi.asp?action=summary&v=1&bookid=127479
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    E-Book (German National Licenses)
  • 7
    Unknown
    The vocation of reason : studies in critical theory and social science in the age of Max Weber (2004)
    Leiden ; Boston : Brill
    International studies in sociology and social anthropology  
    Details
    Keywords: Weber, Max ; Electronic books ; Rationalism ; Sociology, History ; Sociology, Philosophy
    Pages: xlvii, 376 p.
    ISBN: 1-423-71239-0
    URL: http://www.netLibrary.com/urlapi.asp?action=summary&v=1&bookid=133045
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    E-Book (German National Licenses)
  • 8
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    Vorhaben: Offene Navigation und Suchmaschinen in Verbünden, Konsortien und den Wissenschaften; Schlussbericht zumTeilprojekt des BMBF-Vorhabens: Kompetenznetzwerk NeueDienste, Standardisierung, Metadaten. (2004)
    Details
    Publication Date: 2020-03-23
    Description: Die harmonische Integration der Navigation und Suche in lizenzierten Journalen und gleichzeitig in freien digitalen Dokumenten unter einer einheitlichen konsistenten Nutzeroberflache ist eines der ungelösten F&E-Probleme der Fachinformation. Hierfür sollen Elemente des Invisible Web und des Visible Web unter Berücksichtigung offener Standards nahtlos #I miteinander verbunden werden. Dem Projekt liegt ein Modell mit Internet-Index, Metasuche und Open Linking über verteilten heterogenen Speichern #I zu Grunde: Verschiedenste Server, digitale Referenzen in Artikeln und Dokumenten, Links in Datenbanken und auf Bestelldienste sollen unter Berücksichtigung von Standort-, Studien- und Lernbedingungen kooperativ miteinander vernetzt werden. Die Leistungsfähigkeit des Modells soll in Pilotimplementierungen getestet und für eine breite Anwendung vorbereitet werden. Auf dieser Basis soll das Vorhaben Verteilter Zeitschriftenserver der AG der Verbundsysteme in eigenen Teilprojekten kooperativ initiiert werden, das jetzt in das Vorhaben Verteilter Dokumentenserver von vascoda integriert ist.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 9
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    Parameter Estimation and Accuracy Matching Strategies for 2-D Reactor Models (2004)
    Details
    Publication Date: 2014-02-26
    Description: The mathematical modeling of a special modular catalytic reactor kit leads to a system of partial differential equation in two space dimensions. As customary, this model contains unconfident physical parameters, which may be adapted to fit experimental data. To solve this nonlinear least squares problem we apply a damped Gauss-Newton method. A method of lines approach is used to evaluate the associated model equations. By an a priori spatial discretization a large DAE system is derived and integrated with an adaptive, linearly-implicit extrapolation method. For sensitivity evaluation we apply an internal numerical differentiation technique, which reuses linear algebra information from the model integration. In order not to interfere the control of the Gauss-Newton iteration these computations are done usually very accurately and, therefore, very costly. To overcome this difficulty, we discuss several accuracy adaptation strategies, e.g., a master-slave mode. Finally, we present some numerical experiments.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 10
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    Finding All Maximal Cliques of a Family of Induced Subgraphs (2004)
    Details
    Publication Date: 2020-03-06
    Description: Many real world problems can be mapped onto graphs and solved with well-established efficient algorithms studied in graph theory. One such problem is to find large sets of points satisfying some mutual relationship. This problem can be transformed to the problem of finding all cliques of an undirected graph by mapping each point onto a vertex of the graph and connecting any two vertices by an edge whose corresponding points satisfy our desired relationship. Clique detection has been widely studied and there exist efficient algorithms. In this paper we study a related problem, where all points have a set of binary attributes, each of which is either 0 or 1. This is only a small limitation, since all discrete properties can be mapped onto binary attributes. In our case, we want to find large sets of points not only satisfying some mutual relationship; but, in addition, all points of a set also need to have at least one common attribute with value 1. The problem we described can be mapped onto a set of induced subgraphs, where each subgraph represents a single attribute. For attribute $i$, its associated subgraph contains those vertices corresponding to the points with attribute $i$ set to 1. We introduce the notion of a maximal clique of a family, $\mathcal{G}$, of induced subgraphs of an undirected graph, and show that determining all maximal cliques of $\mathcal{G}$ solves our problem. Furthermore, we present an efficient algorithm to compute all maximal cliques of $\mathcal{G}$. The algorithm we propose is an extension of the widely used Bron-Kerbosch algorithm.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 11
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    An Integer Programming Model for Multi-Layer Network Design (2004)
    Details
    Publication Date: 2014-02-26
    Description: We present an integer linear programming model for the design of multi-layer telecommunication networks. The formulation integrates hardware, capacity, routing, and grooming decisions in \emph{any} n umber of network layers. Practical hardware restrictions and cost can accurately be taken into account for technologies based on connection-oriented routing protocols.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 12
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    Compressing Triangle Meshes using Geometric Infomation (2004)
    Details
    Publication Date: 2014-02-26
    Description: We introduce FreeLence, a lossless single-rate connectivity compression algorithm for triangle surface meshes. Based upon a geometry-driven traversal scheme we present two novel and simple concepts: free-valence connectivity encoding and entropy coding based on geometric context. Together these techniques yield significantly smaller rates for connectivity compression than current state of the art approaches - valence-based algorithms and Angle- Analyzer, with an average of $36\%$ improvement over the former and an average of $18\%$ over the latter on benchmark 3D models, combined with the ability to well adapt to the regularity of meshes. We also prove that our algorithm exhibits a smaller worst case entropy for a class of "'well-behaved"' triangle meshes than valence-driven connectivity encoding approaches.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 13
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    Jahresbericht 2003 (2004)
    Details
    Publication Date: 2019-10-24
    Keywords: ddc:000
    Language: German
    Type: annualzib , doc-type:report
    Format: application/pdf
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  • 14
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    Large-scale hierarchical networks: How to compute an optimal architecture? (2004)
    Details
    Publication Date: 2020-02-11
    Description: In this article, we present a mathematical model and an algorithm to support one of the central strategic planning decisions of network operators: How to organize a large number of locations into a hierarchical network? We propose a solution approach that is based on mixed-integer programming and Lagrangian relaxation techniques. As major advantage, our approach provides not only solutions but also worst-case quality guarantees. Real-world scenarios with more than 750 locations have been solved within 30 minutes to less than 1\% off optimality.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 15
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    UMTS Radio Network Evaluation and Optimization beyond Snapshots (2004)
    Details
    Publication Date: 2020-02-11
    Description: This paper is concerned with UMTS radio network design. Our task is to reconfigure antennas and the related cells as to improve network quality. In contrast to second generation GSM networks, \emph{interference} plays a paramount role when designing third generation radio networks. A known compact formulation for assessing the interference characteristics of a radio network as coupling relations between cells based on user snapshots is generalized to statistical average load. This enables us to overcome the notorious difficulties of snapshot-based network optimization approaches. We recall a mixed-integer programming model for the network design problem that is based on user snapshots and contrast it with a new network design model based on the average coupling formulation. Exemplarily focusing on the important problem of optimizing antenna tilts, we give computational results for a fast local search algorithm and the application of a MIP solver to both models. These results demonstrate that our new average-based approaches outperform state-of-the-art snapshot models for UMTS radio network optimization.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 16
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    SCIP - a framework to integrate Constraint and Mixed Integer Programming (2004)
    Details
    Publication Date: 2021-08-05
    Description: Constraint Programs and Mixed Integer Programs are closely related optimization problems originating from different scientific areas. Today's state-of-the-art algorithms of both fields have several strategies in common, in particular the branch-and-bound process to recursively divide the problem into smaller sub problems. On the other hand, the main techniques to process each sub problem are different, and it was observed that they have complementary strenghts. We propose a programming framework {\sffamily SCIP} that integrates techniques from both fields in order to exploit the strenghts of both, Constraint Programming and Mixed Integer Programming. In contrast to other proposals of recent years to combine both fields, {\sffamily SCIP} does not focus on easy implementation and rapid prototyping, but is tailored towards expert users in need of full, in-depth control and high performance.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 17
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    Searching and Classifying Differential Equations on the Web (2004)
    Details
    Publication Date: 2018-12-06
    Description: In this paper we describe the semantic analysis of differential equations given in the ubiquitous semi-structured formats MathML and OpenMath. The analysis is integrated in a deployed Web indexing framework. Starting from basic classifications for differential equations the proposed system architecture is amenable to extensions for further reconstruction of mathematical content on the Web. The syntactic analysis of mathematical formulae given in the considered formats must overcome ambiguities that stem from the fact that formula particles may have different encodings, which are in principle completely arbitrary. However, it turns out that the syntactic analysis can be done straightforward given some natural heuristic assumptions.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 18
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    Anisotropic Filtering of Non-Linear Surface Features (2004)
    Details
    Publication Date: 2014-02-26
    Description: A new method for noise removal of arbitrary surfaces meshes is presented which focuses on the preservation and sharpening of non-linear geometric features such as curved surface regions and feature lines. Our method uses a prescribed mean curvature flow (PMC) for simplicial surfaces which is based on three new contributions: 1. the definition and efficient calculation of a discrete shape operator and principal curvature properties on simplicial surfaces that is fully consistent with the well-known discrete mean curvature formula, 2. an anisotropic discrete mean curvature vector that combines the advantages of the mean curvature normal with the special anisotropic behaviour along feature lines of a surface, and 3. an anisotropic prescribed mean curvature flow which converges to surfaces with an estimated mean curvature distribution and with preserved non-linear features. Additionally, the PMC flow prevents boundary shrinkage at constrained and free boundary segments.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 19
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    Function space interior point methods for PDE constrained optimization (2004)
    Details
    Publication Date: 2019-01-29
    Description: A primal-dual interior point method for optimal control problems with PDE constraints is considered. The algorithm is directly applied to the infinite dimensional problem. Existence and convergence of the central path are analyzed. Numerical results from an inexact continuation method applied to a model problem are shown.
    Keywords: ddc:000
    Language: English
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  • 20
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    Zusammenarbeit mit vascoda im Rahmen des Verteilten Dokumentenservers (VDS) (2004)
    Details
    Publication Date: 2014-02-26
    Description: Die in der Arbeitsgemeinschaft der Verbundsysteme zusammengeschlossenen deutschen Verbundsysteme kooperieren zur Realisierung eines die Länder und Verbundregionen übergreifenden offenen Netzwerkes einer offenen digitalen Bibliothek, dem Verteilten Dokumentenserver (VDS). Wesentliche Bestandteile des VDS sind die in den lokalen Bibliotheken und Verbundsystemen verteilten Dokumentenspeicher. Beim Aufbau des VDS verfolgen die deutschen Verbundsysteme für ihre digitalen Ressourcen, Zeitschriften und Dokumente, folgende Ziele [AGV03]: \begin{itemize} \item{Erhalt und dauerhafte Sicherung einmal erworbener Rechte} \item{Bessere Erschließung und Integration in das eigene Angebot} \item{Nahtlose Navigation in lokalen Zeitschriften- und Dokumentenservern und zwischen digitalen Artikeln und Zeitschriften, Dokumenten und Servern} \item{Dauerhafte Sicherung des Zugriffs und perspektivisch Langzeitverfügbarkeit} \end{itemize} Die Verbundsysteme streben an, die Speicherung, Erschließung und das Angebot ihrer digitalen Materialien in einer nationalen Kooperation durchzuführen. Sie entwickeln und betreiben zu diesem Zweck Portal- und Querschnittstechnologien zur Integration ihrer dezentral gespeicherten digitalen Ressourcen mittels Internet-Technologien.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 21
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    Utility Proportional Fair Bandwidth Allocation - An Optimization Oriented Approach (2004)
    Details
    Publication Date: 2014-02-26
    Description: In this paper, we present a novel approach to the congestion control and resource allocation problem of elastic and real-time traffic in telecommunication networks. With the concept of utility functions, where each source uses a utility function to evaluate the benefit from achieving a transmission rate, we interpret the resource allocation problem as a global optimization problem. The solution to this problem is characterized by a new fairness criterion, \e{utility proportional fairness}. We argue that it is an application level performance measure, i.e. the utility that should be shared fairly among users. As a result of our analysis, we obtain congestion control laws at links and sources that are globally stable and provide a utility proportional fair resource allocation in equilibrium. We show that a utility proportional fair resource allocation also ensures utility max-min fairness for all users sharing a single path in the network. As a special case of our framework, we incorporate utility max-min fairness for the entire network. To implement our approach, neither per-flow state at the routers nor explicit feedback beside ECN (Explicit Congestion Notification) from the routers to the end-systems is required.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 22
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    Die Mathematik der kürzesten Wege. Inhalte und Methoden für den Unterricht (2004)
    Details
    Publication Date: 2014-02-26
    Description: Wie findet man den optimalen Weg im U-Bahnnetz? Das Problem wird als Graph modelliert und dann eine Breitensuche durchgeführt. Will man Weglängen oder Fahrzeiten mitberücksichtigen, so braucht man den Algorithmus von Dijkstra für gewichtige Graphen. Beim Nachdenken über diese Algorithmen werden auch Fragestellungen der Graphentheorie berührt. In einem zweiten Abschnitt werden methodische Hinweise für den Unterricht in der Sekundarstufe I und II gegeben, insbesondere, wie man Lernende dazu bringen kann, ihre Ideen für Algorithmen präzise zu analysieren und zu Papier zu bringen.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 23
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    Perron Cluster Analysis and Its Connection to Graph Partitioning for Noisy Data (2004)
    Details
    Publication Date: 2014-02-26
    Description: The problem of clustering data can be formulated as a graph partitioning problem. Spectral methods for obtaining optimal solutions have reveceived a lot of attention recently. We describe Perron Cluster Cluster Analysis (PCCA) and, for the first time, establish a connection to spectral graph partitioning. We show that in our approach a clustering can be efficiently computed using a simple linear map of the eigenvector data. To deal with the prevalent problem of noisy and possibly overlapping data we introduce the min Chi indicator which helps in selecting the number of clusters and confirming the existence of a partition of the data. This gives a non-probabilistic alternative to statistical mixture-models. We close with showing favorable results on the analysis of gene expressi on data for two different cancer types.
    Keywords: ddc:000
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  • 24
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    Linear Programming Lower Bounds for Minimum Converter Wavelength Assignment in Optical Networks (2004)
    Details
    Publication Date: 2014-02-26
    Description: In this paper, we study the conflict-free assignment of wavelengths to lightpaths in an optical network with the opportunity to place wavelength converters. To benchmark heuristics for the problem, we develop integer programming formulations and study their properties. Moreover, we study the computational performance of the column generation algorithm for solving the linear relaxation of the most promising formulation. In many cases, a non-zero lower bound on the number of required converters is generated this way. For several instances, we in fact prove optimality since the lower bound equals the best known solution value.
    Keywords: ddc:000
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  • 25
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    On PDE Solution in Transient Optimization of Gas Networks (2004)
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    Publication Date: 2021-02-01
    Description: Operative planning in gas distribution networks leads to large-scale mixed-integer optimization problems involving a hyperbolic PDE defined on a graph. We consider the NLP obtained under prescribed combinatorial decisions---or as relaxation in a branch and bound framework, addressing in particular the KKT systems arising in primal-dual interior methods. We propose a custom solution algorithm using sparse local projections, based on the KKT systems' structual properties induced by the discretized gas flow equations in combination with the underlying network topology. The numerical efficiency and accuracy of the algorithm are investigated, and detailed computational comparisons with a control space method and with the multifrontal solver MA27 are provided.
    Keywords: ddc:000
    Language: English
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  • 26
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    Optimization Models for Operative Planning in Drinking Water Networks (2004)
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    Publication Date: 2021-02-01
    Description: The topic of this paper is minimum cost operative planning of pressurized water supply networks over a finite horizon and under reliable demand forecast. Since this is a very hard problem, it is desirable to employ sophisticated mathematical algorithms, which in turn calls for carefully designed models with suitable properties. The paper develops a nonlinear mixed integer model and a nonlinear programming model with favorable properties for gradient-based optimization methods, based on smooth component models for the network elements. In combination with further nonlinear programming techniques (to be reported elsewhere), practically satisfactory near-optimum solutions even for large networks can be generated in acceptable time using standard optimization software on a PC workstation. Such an optimization system is in operation at Berliner Wasserbetriebe.
    Keywords: ddc:000
    Language: English
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  • 27
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    Unterrichtsideen zu Algorithmen der kombinatorischen Optimierung (2004)
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    Publication Date: 2014-02-26
    Description: Im Rahmen von Problemstellungen der kombinatorischen Optimierung können Schülerinnen und Schüler lernen, Algorithmen selber zu entwickeln. Gleichzeitig lernen sie dabei moderne Mathematik in ihren Anwendungen kennen und erleben die Mathematik als lebendige Wissenschaft.
    Keywords: ddc:000
    Language: German
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  • 28
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    Computing Optimal Morse Matchings (2004)
    Details
    Publication Date: 2020-12-15
    Description: Morse matchings capture the essential structural information of discrete Morse functions. We show that computing optimal Morse matchings is NP-hard and give an integer programming formulation for the problem. Then we present polyhedral results for the corresponding polytope and report on computational results.
    Keywords: ddc:000
    Language: English
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  • 29
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    Provably Good Solutions for Wavelength Assignment in Optical Networks (2004)
    Details
    Publication Date: 2014-02-26
    Description: In this paper, we study the minimum converter wavelength assignment problem in optical networks. To benchmark the quality of solutions obtained by heuristics, we derive an integer programming formula tion by generalizing the formulation of Mehrotra and Trick (1996) for the vertex coloring problem. To handle the exponential number of variables, we propose a column generation approach. Computational experiments show that the value of the linear relaxation states a good lower bound and can often prove optimality of the best solution generated heuristically.
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    A Note on Contraction Degeneracy (2004)
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    Publication Date: 2014-11-10
    Description: The parameter contraction degeneracy -- the maximum minimum degree over all minors of a graph -- is a treewidth lower bound and was first defined in (Bodlaender, Koster, Wolle, 2004). In experiments it was shown that this lower bound improves upon other treewidth lower bounds. In this note, we examine some relationships between the contraction degeneracy and connected components of a graph, block s of a graph and the genus of a graph. We also look at chordal graphs, and we study an upper bound on the contraction degeneracy and another lower bound for treewidth. A data structure that can be used for algorithms computing the degeneracy and similar parameters, is also described.
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    On the Maximum Cardinality Search Lower Bound for Treewidth (2004)
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    Publication Date: 2014-11-10
    Description: The Maximum Cardinality Search algorithm visits the vertices of a graph in some order, such that at each step, an unvisited vertex that has the largest number of visited neighbors becomes visited. An MCS-ordering of a graph is an ordering of the vertices that can be generated by the Maximum Cardinality Search algorithm. The visited degree of a vertex $v$ in an MCS-ordering is the number of neighbors of $v$ that are before $v$ in the ordering. The visited degree of an MCS-ordering $\psi$ of $G$ is the maximum visited degree over all vertices $v$ in $\psi$. The maximum visited degree over all MCS-orderings of graph $G$ is called its {\em maximum visited degree}. Lucena (2003) showed that the treewidth of a graph $G$ is at least its maximum visited degree. We show that the maximum visited degree is of size $O(\log n)$ for planar graphs, and give examples of planar graphs $G$ with maximum visited degree $k$ with $O(k!)$ vertices, for all $k\in \Bbb{N}$. Given a graph $G$, it is NP-complete to determine if its maximum visited degree is at least $k$, for any fixed $k\geq 7$. Also, this problem does not have a polynomial time approximation algorithm with constant ratio, unless P=NP. Variants of the problem are also shown to be NP-complete. We also propose and experimentally analyses some heuristics for the problem. Several tiebreakers for the MCS algorithm are proposed and evaluated. We also give heuristics that give upper bounds on the value of the maximum visited degree of a graph, which appear to give results close to optimal on many graphs from real life applications.
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    A new Model for the Free Energy of Solvation and its Application in Protein Ligand Scoring (2004)
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    Publication Date: 2014-02-26
    Description: A new and time efficient model to evaluate the free energy of solvation has been developed. The solvation free energy is separated into an electrostatic term, a hydrogen bond term, and a rest-term, combining both entropic and van der Waals effects. The electrostatic contribution is evaluated with a simplified boundary element method using the partial charges of the MMFF94 force field. The number of hydrogen bonds and the solvent excluded surface area over the surface atoms are used in a linear model to estimate the non-electrostatic contribution. This model is applied to a set of 213 small and mostly organic molecules, yielding an rmsd of 0.87kcal/mol and a correlation with experimental data of r=0.951. The model is applied as a supplementary component of the free energy of binding to estimate binding constants of protein ligand complexes. The intermolecular interaction energy is evaluated by using the MMFF94 force field.
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    Multiple Semi-flexible 3D Superposition of Drug-sized Molecules (2004)
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    Publication Date: 2020-03-06
    Description: In this paper we describe a new algorithm for multiple semi-flexible superpositioning of drug-sized molecules. The algorithm identifies structural similarities of two or more molecules. When comparing a set of molecules on the basis of their three-dimensional structures, one is faced with two main problems. (1) Molecular structures are not fixed but flexible, i.e., a molecule adopts different forms. To address this problem, we consider a set of conformers per molecule. As conformers we use representatives of conformational ensembles, generated by the program ZIBMol. (2) The degree of similarity may vary considerably among the molecules. This problem is addressed by searching for similar substructures present in arbitrary subsets of the given set of molecules. The algorithm requires to preselect a reference molecule. All molecules are compared to this reference molecule. For this pairwise comparison we use a two-step approach. Clique detection on the correspondence graph of the molecular structures is used to generate start transformations, which are then iteratively improved to compute large common substructures. The results of the pairwise comparisons are efficiently merged using binary matching trees. All common substructures that were found, whether they are common to all or only a few molecules, are ranked according to different criteria, such as number of molecules containing the substructure, size of substructure, and geometric fit. For evaluating the geometric fit, we extend a known scoring function by introducing weights which allow to favor potential pharmacophore points. Despite considering the full atomic information for identifying multiple structural similarities, our algorithm is quite fast. Thus it is well suited as an interactive tool for the exploration of structural similarities of drug-sized molecules.
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    Data Management for Processing Molecules (2004)
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    Publication Date: 2014-02-26
    Description: Molecular dynamics simulations of possible ligands for proteins yield large amounts of data in the form of trajectories which are further processed in order to find metastable conformations. These conformations can then be used for docking between ligand and protein. Around this core computation procedure lots of other data have to be managed. It should also be possible for external users not involved in program development to perform computations. As a paradigm for other fields where a similar constitution of program usage and data processing is found we present a software architecture for data generation, access and management. Requirements for this system include: Ease of use, graphical user interface, persistent storage of data concerning molecules, users, programs, program parameters, metadata, and results. A mere storage in the file system would render a quick overview of data more or less impossible. On the other hand, storing large amounts of binary data in a database doesn't yield any advantage concerning speed of access. Therefore, a hybrid approach combining file system and database is appropriate. The system should be easily extensible by inserting new applications which can be controlled and whose results can be collected and stored. The software system described here consists of different components, the presentation layer (graphical user interface), the business logic, the persistence layer (relational database plus file system), and an interface to the compute cluster (batch system for parallel processing). We will discuss the alternatives and take a closer look at the components.
    Keywords: ddc:000
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    Visual Analysis of Molecular Conformations by Means of a Dynamic Density Mixture Model (2004)
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    Publication Date: 2020-03-09
    Description: We propose an approach for transforming the sampling of a molecular conformation distribution into an analytical model based on Hidden Markov Models. The model describes the sampled shape density as a mixture of multivariate unimodal densities. Thus, it delivers an interpretation of the sampled density as a set of typical shapes that appear with different probabilities and are characterized by their geometry, their variability and transition probabilities between the shapes. The gained model is used to identify atom groups of constant shape that are connected by metastable torsion angles. Based on this description an alignment for the original sampling is computed. As it takes into account the different shapes contained in the sampled set, this alignment allows to compute reasonable average shapes and meaningful shape density plots. Furthermore, it enables us to visualize typical conformations.
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    MOMENTUM Data Scenarios for Radio Network Planning and Simulation (Extended Abstract) (2004)
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    Publication Date: 2020-02-11
    Description: We present publicly available data sets related to research on wireless networks. The scenarios contain a wide range of data and are detailed in all aspects. To our knowledge, this is the most realistic, comprehensive, and detailed \emph{public} data collection on mobile networking. We indicate example uses of this data collection in applications related tu UMTS.
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    Models for Line Planning in Public Transport (2004)
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    Publication Date: 2020-12-15
    Description: The \emph{line planning problem} is one of the fundamental problems in strategic planning of public and rail transport. It consists of finding lines and corresponding frequencies in a public transport network such that a given travel demand can be satisfied. There are (at least) two objectives. The transport company wishes to minimize its operating cost; the passengers request short travel times. We propose two new multi-commodity flow models for line planning. Their main features, in comparison to existing models, are that the passenger paths can be freely routed and that the lines are generated dynamically.
    Keywords: ddc:000
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    Triangulated Manifolds with Few Vertices: Centrally Symmetric Spheres and Products of Spheres (2004)
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    Publication Date: 2014-02-26
    Description: The aim of this paper is to give a survey of the known results concerning centrally symmetric polytopes, spheres, and manifolds. We further enumerate nearly neighborly centrally symmetric spheres and centrally symmetric products of spheres with dihedral or cyclic symmetry on few vertices, and we present an infinite series of vertex-transitive nearly neighborly centrally symmetric 3-spheres.
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    Anisotropic Simulation of the Human Mandible (2004)
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    Publication Date: 2019-05-10
    Description: We focus on the role of anisotropic elasticity in the simulation of the load distribution in a human mandible due to a lateral bite on the leftmost premolar. Based on experimental evidence, we adopt ``local''" orthotropy of the elastic properties of the bone tissue. Since the trajectories of anisotropic elasticity are not accessible from Computer Tomographic (CT) data, they will be reconstructed from (i) the organ's geometry and (ii) from coherent structures which can be recognized from the spatial distribution of the CT values. A sensitivity analysis comprising various 3D FE simulations reveals the relevance of elastic anisotropy for the load carrying behavior of a human mandible: Comparison of the load distributions in isotropic and anisotropic simulations indicates that anisotropy seems to ``spare''" the mandible from loading. Moreover, a maximum degree of anisotropy leads to kind of an load minimization of the mandible, expressed by a minimum of different norms of local strain, evaluated throughout the organ. Thus, we may suggest that anisotropy is not only relevant, but also in some sense ``optimal''.
    Keywords: ddc:000
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    Affine conjugate adaptive Newton methods for nonlinear elastomechanics (2004)
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    Publication Date: 2019-05-10
    Description: The paper extends affine conjugate Newton methods from convex to nonconvex minimization, with particular emphasis on PDE problems originating from compressible hyperelasticity. Based on well-known schemes from finite dimensional nonlinear optimization, three different algorithmic variants are worked out in a function space setting, which permits an adaptive multilevel finite element implementation. These algorithms are tested on two well-known 3D test problems and a real-life example from surgical operation planning.
    Keywords: ddc:000
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    A Geometrical Characterization of the Multidimensional Hausdorff and Dale Polytopes with Applications to Exit Time Problems (2004)
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    Publication Date: 2014-02-26
    Description: We present formulae for the corner points of the multidimensional Hausdorff and Dale Polytopes and show how these results can be used to improve linear programming models for computing e.\,g.\ moments of exit distribution of diffusion processes. Specifically, we compute the mean exit time of twodimensional Brownian motion from the unit square and the unit triangle, as well as higher moments of the exit time of time space Brownian motion from a triangle.
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    The Normal Graph Conjecture is true for Circulants (2004)
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    Publication Date: 2014-11-10
    Description: Normal graphs are defined in terms of cross-intersecting set families: a graph is normal if it admits a clique cover $\cal Q$ and a stable set cover $\cal S$ s.t.~every clique in $\cal Q$ intersects every stable set in $\cal S$. Normal graphs can be considered as closure of perfect graphs by means of co-normal products (Körner 1973) and graph entropy (Czisz\'ar et al. 1990). Perfect graphs have been recently characterized as those graphs without odd holes and odd antiholes as induced subgraphs (Strong Perfect Graph Theorem, Chudnovsky et al. 2002). Körner and de Simone observed that $C_5$, $C_7$, and $\overline C_7$ are minimal not normal and conjectured, as generalization of the Strong Perfect Graph Theorem, that every $C_5$, $C_7$, $\overline C_7$- free graph is normal (Normal Graph Conjecture, Körner and de Simone 1999). We prove this conjecture for a first class of graphs that generalize both odd holes and odd antiholes, the circulants, by characterizing all the normal circulants.
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    One-Point Suspensions and Wreath Products of Polytopes and Spheres (2004)
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    Publication Date: 2014-02-26
    Description: It is known that the suspension of a simplicial complex can be realized with only one additional point. Suitable iterations of this construction generate highly symmetric simplicial complexes with a various interesting combinatorial and topological properties. In particular, infinitely many non-PL spheres as well as contactible simplicial complexes with a vertex-transitive group of automorphisms cab be contained in this way.
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    Segmentation of the Liver using a 3D Statistical Shape Model (2004)
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    Publication Date: 2020-03-10
    Description: This paper presents an automatic approach for segmentation of the liver from computer tomography (CT) images based on a 3D statistical shape model. Segmentation of the liver is an important prerequisite in liver surgery planning. One of the major challenges in building a 3D shape model from a training set of segmented instances of an object is the determination of the correspondence between different surfaces. We propose to use a geometric approach that is based on minimizing the distortion of the correspondence mapping between two different surfaces. For the adaption of the shape model to the image data a profile model based on the grey value appearance of the liver and its surrounding tissues in contrast enhanced CT data was developed. The robustness of this method results from a previous nonlinear diffusion filtering of the image data. Special focus is turned to the quantitative evaluation of the segmentation process. Several different error measures are discussed and implemented in a study involving more than 30 livers.
    Keywords: ddc:000
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    Branching rules revisited (2004)
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    Publication Date: 2021-08-05
    Description: Mixed integer programs are commonly solved with linear programming based branch-and-bound algorithms. The success of the algorithm strongly depends on the strategy used to select the variable to branch on. We present a new generalization called {\sl reliability branching} of today's state-of-the-art {\sl strong branching} and {\sl pseudocost branching} strategies for linear programming based branch-and-bound algorithms. After reviewing commonly used branching strategies and performing extensive computational studies we compare different parameter settings and show the superiority of our proposed newstrategy.
    Keywords: ddc:000
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    A Bundle Method for Integrated Multi-Depot Vehicle and Duty Scheduling in Public Transit (2004)
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    Publication Date: 2020-03-09
    Description: This article proposes a Lagrangean relaxation approach to solve integrated duty and vehicle scheduling problems arising in public transport. The approach is based on the proximal bundle method for the solution of concave decomposable functions, which is adapted for the approximate evaluation of the vehicle and duty scheduling components. The primal and dual information generated by the bundle method is used to guide a branch-and-bound type algorithm. Computational results for large-scale real-world integrated vehicle and duty scheduling problems with up to 1,500 timetabled trips are reported. Compared with the results of a classical sequential approach and with reference solutions, integrated scheduling offers remarkable potentials in savings and drivers' satisfaction.
    Keywords: ddc:000
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    Adaptive Finite Element Simulation of the Human Mandible Using a New Physiological Model of the Masticatory Muscles (2004)
    Details
    Publication Date: 2019-05-10
    Description: Structural mechanics simulation of bony organs is of general medical and biomechanical interest, because of the interdependence of the inner architecture of bone and its functional loading already stated by Wolff in 1892. This work is part of a detailed research project concerning the human mandible. By adaptive finite element techniques, stress/strain profiles occurring in the bony structure under biting were simulated. Estimates of the discretization errors, local grid refinement, and multilevel techniques guarantee the reliability and efficiency of the method. In general, our simulation requires a representation of the organ's geometry, an appropriate material description, and the load case due to teeth, muscle, or joint forces. In this paper, we want to focus on the influence of the masticatory system. Our goal is to capture the physiological situation as far as possible. By means of visualization techniques developed by the group, we are able to extract individual muscle fibres from computed tomography data. By a special algorithm, the fibres are expanded to fanlike (esp. for the musc. temporalis) coherent vector fields similar to the anatomical reality. The activity of the fibres can be adapted according to compartmentalisation of the muscles as measured by electromyological experiments. A refined sensitivity analysis proved remarkable impact of the presented approach on the simulation results.
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    KKT Systems in Operative Planning for Gas Distribution Networks (2004)
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    Publication Date: 2021-02-01
    Description: Operative planning in gas networks with prescribed binary decisions yields large scale nonlinear programs defined on graphs. We study the structure of the KKT systems arising in interior methods and present a customized direct solution algorithm. Computational results indicate that the algorithm is suitable for optimization in small and medium-sized gas networks.
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    Indexierung von Online-Katalogen: Ein gemeinsames Konzept der ALEPH-Anwender in Berlin (2004)
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    Publication Date: 2021-02-05
    Description: Der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) verzichtet auf eine einheitliche zentrale Verbunddatenbank zugunsten einer dezentralen, verteilten Struktur. In dieser Architektur erhält die Art der Indexierung der angesprochenen Online-Kataloge eine besondere Bedeutung. So werden sowohl Bibliotheksmitarbeiter als auch Bibliotheksbenutzer immer wieder mit der Recherche in fremden Katalogen konfrontiert, in denen unterschiedliche Indexierungsverfahren realisiert sein können. Ein abgestimmtes Indexierungskonzept verfolgt zwei grundsätzliche Ziele. Einerseits soll durch eine vereinheitlichte Indexierung die Qualität und Zuverlässigkeit der Rechercheergebnisse in der parallelen Suche in mehreren Katalogen über die KOBV-Suchmaschine erhöht werden. Gleichzeitig soll durch eine vereinheitlichte Indexierung die Akzeptanz von Suchen in entfernten Katalogen prinzipiell gesteigert und damit die Bedingungen für die gegenseitige Übernahme von Titeldaten erleichtert werden. Für die Indexierung muss zunächst die Art und der Umfang der im OPAC aufzubauenden Indices festgelegt werden. Aus Sicht des Nutzers entspricht diese Definition den möglichen Sucheinstiegen. Hat man dann entschieden, welche Indexterme aus welchen Feldern in die jeweiligen Indices einfließen sollen, muss bestimmt werden, nach welchen Regeln die Terme behandelt werden. Hier stellt sich insbesondere das Problem der Sonderzeichen wie Bindestriche, Apostrophe und Punkte oder Ziffern in Zeichenketten. Das vorliegende Konzept entstand in Zusammenarbeit der großen Universitätsbibliotheken in Berlin (der Freien Universität, der Humboldt-Universität, der Technischen Universität, der Universität der Künste) mit der KOBV-Verbundzentrale am ZIB.
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    Language: German
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    Integrable quadratic Hamiltonians on so(4) and so(3,1) (2004)
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    Publication Date: 2014-02-26
    Description: We investigate a special class of quadratic Hamiltonians on $so(4)$ and $so(3,1)$ and describe Hamiltonians that have additional polynomial integrals. One of the main results is a new integrable case with an integral of sixth degree.
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    Holes, Antiholes and Maximal Cliques in a Railway Model for a Single Track (2004)
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    Publication Date: 2020-11-16
    Description: We present a graph theoretical model for scheduling trains on a single unidirectional track between two stations. The set of departures of all possible train types at all possible (discrete) points of time is turned into an undirected graph $\Gneu$ by joining two nodes if the corresponding departures are in conflict. This graph $\Gneu$ has no odd antiholes and no $k$-holes for any integer $k\geq 5$. In particular, any finite, node induced subgraph of $\Gneu$ is perfect. For any integer $r\geq 2$ we construct minimal headways for $r$ train types so that the resulting graph $\Gneu$ has $2r$-antiholes and $4$-holes at the same time. Hence, $\Gneu$ is neither a chordal graph nor the complement of a chordal graph, in general. At the end we analyse the maximal cliques in $G$.
    Keywords: ddc:000
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    Robust Process Control by Dynamic Stochastic Programming (2004)
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    Publication Date: 2021-02-01
    Description: Unnecessarily conservative behavior of standard process control techniques can be avoided by stochastic programming models when the distribution of random disturbances is known. In an earlier study we have investigated such an approach for tank level constraints of a distillation process. Here we address techniques that have accelerated the numerical solution of the large and expensive stochastic programs by a factor of six, and then present a refined optimization model for the same application.
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    The Effect of Hop Limits on Optimal Cost in Survivable Network Design (2004)
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    Publication Date: 2014-02-26
    Description: We investigate the impact of hop-limited routing paths on the total cost of a telecommunication network. For different survivability settings (dedicated protection, link and path restoration), the optimal network cost without restrictions on the admissible path set is compared to the results obtained with two strategies to impose hop limits on routing paths. In a thorough computational study on optimal solutions for nine real-world based problem instances, we show that hop limits should be avoided if the technology allows it and network cost is a major planning issue. In this case, column generation should be employed to deal with all routing paths. If hop-limits are required, these should be defined for each demand individually and as large as possible.
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    Reoptimization Gaps versus Model Errors in Online-Dispatching of Service Units for ADAC (2004)
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    Publication Date: 2020-11-13
    Description: Under high load, the automated dispatching of service vehicles for the German Automobile Association (ADAC) must reoptimize a dispatch for 100--150 vehicles and 400 requests in about ten seconds to near optimality. In the presence of service contractors, this can be achieved by the column generation algorithm ZIBDIP. In metropolitan areas, however, service contractors cannot be dispatched automatically because they may decline. The problem: a model without contractors yields larger optimality gaps within ten seconds. One way-out are simplified reoptimization models. These compute a short-term dispatch containing only some of the requests: unknown future requests will influence future service anyway. The simpler the models the better the gaps, but also the larger the model error. What is more significant: reoptimization gap or reoptimization model error? We answer this question in simulations on real-world ADAC data: only the new model ZIBDIP{\footnotesize dummy} can keep up with ZIBDIP.
    Keywords: ddc:000
    Language: English
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    Contraction and Treewidth Lower Bounds (2004)
    Details
    Publication Date: 2020-11-13
    Description: Edge contraction is shown to be a useful mechanism to improve lower bound heuristics for treewidth. A successful lower bound for treewidth is the degeneracy: the maximum over all subgraphs of the minimum degree. The degeneracy is polynomial time computable. We introduce the notion of contraction degeneracy: the maximum over all minors of the minimum degree. We show that the contraction degeneracy problem is NP-complete, even for bipartite graphs, but for fixed $k$, it is polynomial time decidable if a given graph $G$ has contraction degeneracy at least $k$. Heuristics for computing the contraction degeneracy are proposed and evaluated. It is shown that these can lead in practice to considerable improvements of the lower bound for treewidth, but can perform arbitrarily bad on some examples. A study is also made for the combination of contraction with Lucena's lower bound based on Maximum Cardinality Search (Lucena, 2003). Finally, heuristics for the treewidth are proposed and! evaluated that combine contraction with a treewidth lower bound technique by Clautiaux et al (2003).
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    Das KOBV-Portal, elektronische Ressourcen in Berlin-Brandenburg: Nachweis, parallele Suche und weiterführende Dienste (2004)
    Details
    Publication Date: 2020-11-13
    Description: \documentclass[12pt]{article} \usepackage{german} \parindent=0pt \begin{document} Der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) hat in den Jahren 2001 bis 2003 im Rahmen des Entwicklungsprojektes ''KOBV-Informationsportal`` ein regionales Portal aufgebaut, in dem integrierte Informationsdienste fr die regionalen Bibliotheken zur Verfügung gestellt werden. Das ''KOBV-Portal - Digitale Bibliothek Berlin-Brandenburg`` wurde im Dezember 2003 in Betrieb genommen. Das KOBV-Portal bietet in seiner ersten Ausbaustufe den Nachweis über die in den großen Bibliotheken lizenzierten Ressourcen und elektronischen Zeitschriften, zudem die nahtlose Navigation mittels des Reference-Linking-Werkzeuges SFX zu verschiedenen Diensten wie Fernleihe, Subito und freien Volltexten im Internet sowie zu frei zugänglichen elektronischen Zeitschriften. Realisiert wurden ferner die Remote-Authentifizierung, mit der sich ein Nutzer, der online eine Fernleih-Bestellung aufgeben möchte, über das Internet in seiner Heimatbibliothek authentifizieren kann. Des weiteren ist der Zugriff auf lizenzierte Bestände im Campus einer Hochschule mittels IP-Checking möglich. Als weiteren wesentlichen Bestandteil des KOBV-Portals hat die KOBV-Zentrale mit den Bibliotheken einen Workflow für ein Metadata-Sharing abgestimmt und für die Adaption und Normalisierung lokaler Metadaten aus lokalen Bibliothekssystemen und -Portalen den KOBV-Metadaten-Austausch-Parser (KMA-Parser) entwickelt. Damit Bibliotheken, deren Metadaten bislang lediglich in unstrukturierter Form vorliegen, strukturierte Metadaten anlegen, liefern und nachnutzen können, hat die KOBV-Zentrale das mit einer Web-Katalogisierungsschnittstelle ausgestattete ''Metadata-Tool`` entwickelt. Die für das Metadata-Sharing entwickelten Komponenten und Module sollen den Bibliotheken die Mehrfacherfassung ersparen und ihnen die Möglichkeit der wechselseitigen Nachnutzung der Metadaten eröffnen. Der vorliegende Projekt-Abschlussbericht gibt einen Überblick über die während der Projektlaufzeit realisierten Dienste des KOBV-Portals. \end{document}
    Keywords: ddc:000
    Language: German
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    Wie komme ich optimal zum Ziel? Unterricht über kürzeste-Wege-Algorithmen für Graphen (2004)
    Details
    Publication Date: 2014-02-26
    Description: Kürzeste Wege tauchen fast überall im Alltag auf. Daher eignet sich dieses Optimierungsproblem gut für den Unterricht. Modellierung und heuristische Vorgehensweisen werden geübt, um schließlich die klassischen kürzesten Wege-Algorithmen selbst zu erfinden. In diesem Artikel werden die Inhalte vorgestellt und konkrete Hinweise zum Unterricht in der Schule gegeben.
    Keywords: ddc:000
    Language: German
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  • 58
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    A Control Reduced Primal Interior Point Method for PDE Constrained Optimization (2004)
    Details
    Publication Date: 2019-01-29
    Description: A primal interior point method for control constrained optimal control problems with PDE constraints is considered. Pointwise elimination of the control leads to a homotopy in the remaining state and dual variables, which is addressed by a short step pathfollowing method. The algorithm is applied to the continuous, infinite dimensional problem, where discretization is performed only in the innermost loop when solving linear equations. The a priori elimination of the least regular control permits to obtain the required accuracy with comparable coarse meshes. Convergence of the method and discretization errors are studied, and the method is illustrated at two numerical examples.
    Keywords: ddc:000
    Language: English
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  • 59
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    Hierarchical Infrastructure Planning in Networks (2004)
    Details
    Publication Date: 2020-02-11
    Description: In this article, strategical infrastructure planning problems in the design of large-scale telecommunication networks are discussed based on experiences from three projects with industrial partners: The access network planning of the German Gigabit-Wissenschaftsnetz (G-WiN) for DFN (Verein zur Förderung eines Deutschen Forschungsnetzes e.V.), the mobile network switching center location planning project for E-Plus Mobilfunk, and the fixed network switching center location planning project for TELEKOM AUSTRIA. We introduce a mathematical model for a hierarchical multi-commodity capacitated facility location problem, present adaptions of this basic model to the specific requirements within the different projects and discuss the individual peculiarities and model decisions made. Eventually, we present and discuss computational results of three associated case studies, illustrating '"how we did the job`` with mathematical methods.
    Keywords: ddc:000
    Language: English
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  • 60
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    Degree-Based Treewidth Lower Bounds (2004)
    Details
    Publication Date: 2014-11-10
    Description: Every lower bound for treewidth can be extended by taking the maximum of the lower bound over all subgraphs or minors. This extension is shown to be a very vital idea for improving treewidth lower bounds. In this paper, we investigate a total of nine graph parameters, providing lower bounds for treewidth. The parameters have in common that they all are the vertex-degree of some vertex in a subgra ph or minor of the input graph. We show relations between these graph parameters and study their computational complexity. To allow a practical comparison of the bounds, we developed heuristic algorithms for those parameters that are NP-hard to compute. Computational experiments show that combining the treewidth lower bounds with minors can considerably improve the lower bounds.
    Keywords: ddc:000
    Language: English
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    The convergence of an interior point method for an elliptic control problem with mixed control-state constraints (2004)
    Details
    Publication Date: 2019-01-29
    Description: The paper addresses primal interior point method for state constrained PDE optimal control problems. By a Lavrentiev regularization, the state constraint is transformed to a mixed control-state constraint with bounded Lagrange multiplier. Existence and convergence of the central path are established, and linear convergence of a short-step pathfollowing method is shown. The behaviour of the regularizations are demonstrated by numerical examples.
    Keywords: ddc:000
    Language: English
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  • 62
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    Homogenization for a Nonlocal Coupling Model (2004)
    Details
    Publication Date: 2014-02-26
    Description: In [7,8,12] homogenization techniques are applied to derive an anisotropic variant of the bio-heat transfer equation as asymptotic result of boundary value problems providing a microscopic description for microvascular tissue. In view of a future application on treatment planning in hyperthermia, we investigate here the homogenization limit for a coupling model, which takes additionally into account the influence of convective heat transfer in medium size blood vessels. This leads to second order elliptic boundary value problems with nonlocal boundary conditions on parts of the boundary. Moreover, we present asymptotic estimates for first order correctors.
    Keywords: ddc:000
    Language: English
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  • 63
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    Polynomial Inequalities Representing Polyhedra (2004)
    Details
    Publication Date: 2014-02-26
    Description: Our main result is that every $n$-dimensional polytope can be described by at most $2n-1$ polynomial inequalities and, moreover, these polynomials can explicitly be constructed. For an $n$-dimensional pointed polyhedral cone we prove the bound $2n-2$ and for arbitrary polyhedra we get a constructible representation by $2n$ polynomial inequalities.
    Keywords: ddc:000
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    Das KOBV-Metadaten-Schema im KOBV-Portal (2004)
    Details
    Publication Date: 2023-10-05
    Description: Das KOBV-Metadaten-Schema ist von der KOBV-Zentrale entwickelt worden, um Ressourcen im Sinn von Informationskollektionen wie Datenbanken oder Fachportale zu beschreiben. Es ist ein wichtiger Bestandteil des KOBV-Portals, das die in der Region verf"ugbaren Ressourcen nachweist. Das KOBV-Metadaten-Schema dient den Bibliotheken zur Handreichung, um dem KOBV-Portal die Ressourcen mit den standardisierten und individuellen Angaben zu melden, so dass die Ressourcebeschreibungen einem austauschbaren Format entsprechen. Auf diese Weise k"onnen Ressourcebeschreibungen von anderen Bibliotheken mitgenutzt werden und ein Metadata-Sharing in der Region Berlin-Brandenburg praktiziert werden, um in diesem Bereich doppelte Arbeiten zu sparen.
    Keywords: ddc:000
    Language: German
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  • 65
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    Effects of acute administration of cyclazocine on the metabolism of biogenic amines in different regions of rat brain (1981)
    Springer
    Psychopharmacology 75 (1981), S. 79-83 
    Details
    ISSN: 1432-2072
    Keywords: Cyclazocine ; Acute treatment ; Dopamine ; Noradrenaline ; Serotonin ; Monoamine metabolites ; Brain regional assay ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of cyclazocine on the metabolism of dopamine (DA), noradrenaline (NA) and 5-hydroxytryptamine (5-HT) in regions of rat brain were studied by measuring changes in the levels of the monoamines and their major metabolites. Doses ranging from 4–32 mg/kg were tested. Rats were sacrificed 1 or 2 h after administration of the drug, according to the experiment. Administration of cyclazocine significantly decreased DA concentration and increased the levels of DOPAC and HVA in striatum. Cyclazocine decreased the levels of NA, and markedly increased the levels of MHPG-SO4 and 5-HIAA in cortex, hypothalamus, midbrain and pons-medulla, while little change in 5-HT concentration, except a decrease after the highest dose, was observed. These changes in the metabolism of the monoamines differed in their amplitude and temporal nature. The possible roles of dopaminergic, noradrenergic and serotoninergic neurons in different brain regions are discussed in relation to modifications of locomotor activity and the induction of bizarre behavior resulting from cyclazocine administration in rats. These investigations may add to the understanding of the mechanism of psychotomimetic effects produced in man by this drug.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00433507
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  • 66
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    Effect of modification of brain serotonin (5-HT), norepinephrine (NE) and dopamine (DA) on ethanol tolerance (1981)
    Springer
    Psychopharmacology 75 (1981), S. 231-235 
    Details
    ISSN: 1432-2072
    Keywords: Ethanol tolerance ; Serotonin ; Norepinephrine ; Dopamine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats were permanently depleted of brain dopamine (DA), serotonin (5-HT), 5-HT+norepinephrine (NE), or NE +DA by intraventricular injection of either 5,7-dihydroxytryptamine (5,7-DHT) or 6-hydroxydopamine (6-OHDA) with or without pretreatment with desmethylimipramine (DMI). Following 1 week of recovery from surgery, daily treatment with ethanol (5 g/kg, PO) or isocaloric sucrose was carried out for a period of 20–25 days. Testing at 5-day intervals showed that chronic ethanol treatment produced tolerance to the hypothermic and motor impairing effects of ethanol. Depletion of 5-HT alone retarded tolerance, while depletion of NE or DA alone produced no effect. Combined depletion of both NE and 5-HT, however, completely inhibited tolerance development. The inhibition of tolerance development by combined depletion of both NE and 5-HT is dicussed in terms of a reciprocal relationship between these two systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432429
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  • 67
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    A water lick conflict paradigm using drug experienced rats (1981)
    Springer
    Psychopharmacology 75 (1981), S. 236-239 
    Details
    ISSN: 1432-2072
    Keywords: Water lick paradigm ; Punishment suppressed behaviour ; Conflict ; Anxiolytics ; Serotonin antagonism ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A modified water-lick conflict paradigm is described, using trained rats for up to 35 weekly test sessions under 48 h of water deprivation. The rats rapidly became maximally suppressed by the punishment. This suppression was attenuated by the anxiolytics lorazepam, diazepam, phenobarbital, and meprobamate. The potentially anxiolytic drug CL 218872 and the anticonvulsant drug valproate sodium were also active. The antiserotonin drugs methysergide, cyproheptadine, cinanserin and parachlorophenylalanine were all inactive, as were several other distinct classes of psychotropic drugs including propranolol, clonidine, THIP, theophylline, chlorpromazine, paroxetine and ethanol. The paradigm proved reliable, reproducible and useful for large scale investigations. Furthermore, it may provide means for detailed neuropharmacological and anatomical studies.
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    URL: http://dx.doi.org/10.1007/BF00432430
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  • 68
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    Effects of ovariectomy, castration, and chronic lithium chloride treatment on stereotyped behavior in rats (1981)
    Springer
    Psychopharmacology 75 (1981), S. 273-276 
    Details
    ISSN: 1432-2072
    Keywords: Ovariectomy ; Castration ; Chronic LiCl treatment ; Apomorphine ; Stereotyped behavior ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of ovariectomy, castration, and chronic lithium chloride treatment on stereotyped behavior (SB) induced by apomorphine (APO) (0.3–0.6 mg/kg) were investigated in rats. Duration of stereotyped behavior (interval between APO injection and termination of SB) increased in ovariectomized rats compared to female control rats. Castration had no effect on the duration of stereotyped behavior. On the other hand, ovariectomized rats that were treated chronically with LiCl (2 mEq/kg daily) showed no difference in duration of stereotyped behavior compared to female controls chronically treated with LiCl. Neither treatment group showed a significantly altered intensity of stereotyped behavior compared with the appropriate control. These findings are consisten with the hypothesis that estrogen deficit contributes to a greater incidence of neuroleptic-induced tardive dyskinesia in postmenopausal women than in men of comparable age. Furthermore, LiCl may attenuate the symptoms associated with increased postsynaptic dopamine receptor sensitivity following ovariectomy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432437
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  • 69
    Electronic Resource
    Electronic Resource
    Effects of irradiation on the submandibular gland of the rat (1981)
    Springer
    Virchows Archiv 391 (1981), S. 291-299 
    Details
    ISSN: 1432-2307
    Keywords: Submandibular gland ; Rat ; Irradiation ; Enzyme histochemical study ; Ultrastructural study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Single-dose cervical irradiation by cobalt 60 in rats induced lasting functional disturbances of the submandibular gland which were excessive when compaired with the relative integrity of the gland as seen under the light microscope. Enzyme histochemical and ultrastructural studies revealed severe damage shortly after exposure with appearance of karyolytic bodies and autophagosomes accompanied by increased hydrolase activity. Mitochondrial alterations were concomitant with diminished ductal oxidative enzyme activity. Although most of these alterations resolved rapidly as a result of acinar and ductal cell repair and regeneration originating in the intercalated ducts, secretory abnormalities were still observed two months after exposure as evidenced by the accumulation of granules in acinar cells and the heterogeneity of ductal cell granules. These anomalies, comparable to those observed in sialadenoses, probably result from persistent alterations of intralobular nerve endings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00709161
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  • 70
    Electronic Resource
    Electronic Resource
    Pathogenesis of lung tumors induced by N-nitrosoheptamethyleneimine in F344 rats (1981)
    Springer
    Virchows Archiv 393 (1981), S. 333-343 
    Details
    ISSN: 1432-2307
    Keywords: NHMI ; Pathogenesis ; Lung tumors ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Male F344 rats were given 3 mg N-nitrosoheptamethyleneimine (NHMI) per 100 g in olive oil by gavage twice a week for a maximum of 20 weeks. They were killed at predetermined intervals after the start of treatment and the sequential development of NHMI-induced squamous carcinomas in the lungs was followed by light and electron microscopy. Hypertrophy of the endoplasmic reticulum in mucous and Clara cells seen in an initial study suggested that these cells were involved in metabolic activation of the nitrosamine. Basal cells were identified as the cell type that later responded by proliferation, hyperplasia, and squamous metaplasia. Only in the bronchioles, where basal cells are not found in the healthy rat, did these lesions progress further to form squamous cell carcinomas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00430833
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  • 71
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    The role of dopaminergic mechanisms in the rat hippocampus for the consolidation in a brightness discrimination (1981)
    Springer
    Psychopharmacology 75 (1981), S. 165-168 
    Details
    ISSN: 1432-2072
    Keywords: Rat ; Hippocampus ; Dopaminergic receptors ; Apomorphine ; Haloperidol ; Memory consolidation ; Brightness discrimination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Post-training intrahippocampal injection of the dopaminergic agonists apomorphine and ergometrine improved retention in a brightness discrimination task. The dopamine receptor blocker haloperidol caused an impairment of retention and antagonized improvement by apomorphine. An involvement of hippocampal dopaminergic mechanisms in memory consolidation processes was suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432180
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  • 72
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    The influence of some neurotransmitter agonists and antagonists on the response of hippocampal units and the cortical EEG to ethanol in the awake rat (1981)
    Springer
    Psychopharmacology 75 (1981), S. 327-334 
    Details
    ISSN: 1432-2072
    Keywords: Hippocampal units ; Cortical EEG ; Ethanol ; Adrenergic antagonists ; GABAergic antagonists ; Cholinergic agonists ; Dopaminergic agonists ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The spontaneous activity of single unit populations in the dorsal hippocampus and the cortical EEG were monitored in the awake rat. Experiments consisted of three consecutive recording periods; a drug-free baseline period, a pretreatment period and an ethanol period. Pretreatment with doses of dopaminergic or cholinergic agonists, which produced decreases in unit rate and an awake EEG attenuated the inhibitory effect of ethanol on hippocampal unit activity and reduced the amount of high-amplitude, slow (HAS), drowsy-state activity. GABAergic and adrenergic antagonists, which increased hippocampal unit rate, did not attenuate and sometimes enhanced the ethanol-induced inhibition in firing rate but had little additional effect on the EEG. These results point to the involvement of hippocampal neurons in those behavioural aspects of ethanol intoxication mediated by activity in the neurotransmitter systems examined here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00435847
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  • 73
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    Enduring behavioural and biochemical effects in the adult rat after prolonged postnatal administration of haloperidol (1981)
    Springer
    Psychopharmacology 74 (1981), S. 166-169 
    Details
    ISSN: 1432-2072
    Keywords: Postnatal treatment ; Haloperidol ; Apomorphine ; Stereotyped behaviour ; Locomotion ; Learning ; DOPAC ; HVA ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats were administered 0.5 mg/kg SC of haloperidol (H) or saline (S) daily from day 1 after birth until 20 days of age. At 60 days of age (40 days after the postnatal treatment with H or S was interrupted) the stereotyped behaviour and the effects on locomotor activity elicited by apomorphine in S- and H-pretreated rats were investigated. The intensity of apomorphine (0.5–1 mg/kg, SC)-induced stereotyped behaviour was significantly greater in the H-pretreated group than in S-pretreated animals and this was accompanied by a much more marked reduction of locomotor activity in H-pretreated than in S-pretreated rats. Finally, at 80 days of age (60 days after the postnatal treatment with H or S was interrupted) rats were subjected to a Differential Reinforcement of Low Rates schedule (DRL 15-s). The results indicate that the acquisition of the DRL task performance criterion (Rs/Rf≤2.5) was significantly more rapid in S-pretreated rats than in H-pretreated ones. In parallel biochemical experiments, acute H produced smaller increases in dopamine turnover in chronic H-treated rats compared with S-treated controls. These data indicate that H treatment in neonatal rats induces behavioural and biochemical changes which can be observed up to 60 days after H withdrawal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432686
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  • 74
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    Studies on the disposition of Li+ in the guinea-pig and rat (1981)
    Springer
    Psychopharmacology 74 (1981), S. 374-378 
    Details
    ISSN: 1432-2072
    Keywords: Lithium ; Li+ disposition ; Na+-dependent Li+ countertransport process ; Guinea-pig ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats or guinea-pigs were given LiCl acutely (2 mmol/kg IP or intragastrically) or chronically (daily doses 0.6–4 mmol/kg) and plasma, erythrocytes, kidney, liver and brain were analysed for Li+. Generally, after acute LiCl, tissue Li+ levels followed changes in plasma Li+ levels. However, brain Li+ concentrations changed more slowly and in the rat, but not in the guinea-pig, paralleled erythrocyte Li+ concentrations. Li+ was absorbed more slowly from the gastrointestinal tract of the rat. After chronic LiCl, the erythrocyte: plasma Li+ ratio was about 0.1 in the guinea-pig and about 2 in the rat. Relative Li+ tissue concentrations were as follows: guinea-pig, plasma〉kidney〉liver〉brain〉 erythrocyte; rat≫erythrocyte=brain〉liver=plasma. A Na+-dependent Li+ efflux was demonstrated in the erythrocytes of the guinea-pig and human, but not the rat. This process was inhibited by phloretin (0.2 mM), but not frusemide (2.0 mM). The marked differences in the activity of the erythrocyte Na+-dependent Li+ countertransport process in the guinea-pig and rat could extend to other tissues and explain the observed interspecies differences in tissue Li+ distribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432751
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  • 75
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    Naloxone prevention of morphine LDR curve flattening associated with high-dose tolerance (1981)
    Springer
    Psychopharmacology 75 (1981), S. 132-133 
    Details
    ISSN: 1432-2072
    Keywords: Morphine tolerance ; Log-dose/response curve flattening ; Naloxone prevention ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Male wistar rats, previously made tolerant to morphine by at least 3 weeks of daily intraperitoneal (IP) injections of 20 mg/kg morphine-SO4 (MS), were then given 200 mg/kg MS daily for 4 or 5 days. Tail immersion tests of antinociception, carried out before and after the 200 mg/kg MS treatment, indicated that the additional morphine treatment was followed by a large further decrease in opiate sensitivity, characterized by decreased slope of the log-dose/response curve (LDR curve flattening). The further decrease in opiate sensitivity was substantially reduced by naloxone-HCl (IP) in a dose of 10 mg/kg given 30 min before and 8 h after the 200 mg/kg MS injections, or a dose of 4 mg/kg given 45 min after the MS. It was concluded that LDR curve flattening produced by high doses of MS is mediated by specific opiate receptors, and is a true expression of a high degree of opiate tolerance in the intact rat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432174
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  • 76
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    Investigations on behavioral effects of an extract of Cannabis sativa L. in the rat (1981)
    Springer
    Psychopharmacology 75 (1981), S. 144-147 
    Details
    ISSN: 1432-2072
    Keywords: Cannabis ; catecholamines ; Hyperreactivity ; Hyperthermia ; Pimozide ; Atropine ; 6-OHDA ; Stereotypy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The behavioral responses of the rat to an extract of Cannabis sativa were examined after IP injection of 5, 15 and 30 mg/kg (expressed as Δ 9 tetrahydrocannabinol). The lowest dose of the extract induced stereotyped behavior (rhythmic head movements, intermittent gnawing and sniffing) together with hypersensitivity to stimuli and hyperthermia. The administration of higher doses of the extract resulted, initially, in similar behavioral effects but of greater intensity, followed by a cataleptic state alternating with atonic muscular prostration; rectal temperature was decreased. Pre-treatment with 6-hydroxydopamine (6-OHDA, which produces degeneration of catecholamine-containing nerve terminals) or pimozide (blocker of dopamine receptors) significantly reduced both stereotypy and hyperreactivity. Thermic effects were also antagonized by 6-OHDA pre-treatment. Cannabis-induced catalepsy was enhanced by pimozide but reduced by atropine (3 mg/kg SC). These results support the hypothesis that catecholamines play an important role in the complex behavioral effects of cannabis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432176
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  • 77
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    Electronic Resource
    Quantification of tremor in rats induced by physostigmine (1981)
    Springer
    Psychopharmacology 74 (1981), S. 275-279 
    Details
    ISSN: 1432-2072
    Keywords: Animal model ; Tremor intensity ; Quantification ; Physostigmine ; Atropine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A simple and accurate device for recording tremor intensity in unanaesthetized and unrestrained rats is described. The physical measures of tremor are shown to have several advantages over previous devices. First, the new apparatus, unlike some earlier ones, does not restrict the animal's movements to an unusually small cage, with weighty mechanical devices or with electrical leads. Second, most earlier methods for measuring tremor use a subjective rating scale. However, the present method uses objective and reliable measures. In a double-blind, illustrative experiment involving complete crossover, Wistar rats were randomly injected IP with physostigmine in doses of 0.2, 0.4, 0.6 and 0.8 mg/kg or the corresponding amount of 0.9% NaCl solution as control. The recorded tremor intensity showed a clear dose-response relationship for physostigmine. Moreover, linear regression of the dose-response relationship showed that tremor intensity increased linearly with increasing doses of physostigmine. The cholinergic antagonist atropine (0.3 mg/kg SC) antagonized physostigmine-induced tremor, whereas methylatropine (0.3 mg/kg SC) tended to potentiate it. These results show that the technique described is suitable for quantification of tremor intensity in rats and for testing drug interactions on physostigmine-induced tremor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427110
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  • 78
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    Gnawing and changes in reactivity produced by microinjections of picrotoxin into the superior colliculus of rats (1981)
    Springer
    Psychopharmacology 75 (1981), S. 198-203 
    Details
    ISSN: 1432-2072
    Keywords: Superior colliculus ; Oral stereotypy ; Picrotoxin ; Reactivity ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Lesions of the superior colliculus in rats attenuate the oral stereotypy produced by systemic administration of dopamine agonists. Current evidence suggests that such drugs affect the superior colliculus by reducing transmission in the inhibitory GABAergic nigrotectal pathway. To investigate whether the superior colliculus plays a direct role in producing stereotyped oral movements, the present experiment therefore examined the effects of collicular microinjections of the GABA antagonist picrotoxin on the behaviour of rats observed in an open-field. Gnawing was observed after injections of picrotoxin (25 ng) into sites in the intermediate and deep layers of the superior colliculus, consistent with the superior colliculus playing a direct part in producing the stereotyped gnawing seen after systemic administration of dopamine agonists. However, gnawing was only observed after a period in which the animal showed strong avoidance reactions, to stimuli that normally evoked orienting or little reaction. This change in reactivity was observed after injections of picrotoxin into all parts of the colliculus, but the most sensitive (responding to doses as low as 12.5 ng) were mainly in the superficial and intermediate layers. It appears that there may be more than one GABAergic system within the superior colliculus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432187
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  • 79
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    Collicular picrotoxin alleviates akinesia but not sensory neglect in rats with bilateral 6-hydroxydopamine lesions of ventral midbrain (1981)
    Springer
    Psychopharmacology 75 (1981), S. 204-209 
    Details
    ISSN: 1432-2072
    Keywords: 6-Hydroxydopamine ; Sensorimotor deficits ; Superior colliculus ; Picrotoxin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Anatomical and biochemical investigations have suggested that GABA transmission in the superior colliculus consequent upon activity of the nigrotectal pathway is increased following 6-hydroxydopamine (6-OHDA) lesions of the ascending dopamine systems. Moreover, it has been proposed that this increase in inhibitory activity within the colliculus may be responsible for the sensory neglect commonly observed after dopamine denervation. The present experiment sought to test this proposal by examining the effects of injections of the GABA antagonist picrotoxin into the superior colliculus of 6-OHDA lesioned rats, in the hope that the neglect caused by the 6-OHDA would be reversed. However, in 33 of 36 cases studied intracollicular microinjections of picrotoxin produced no detectable improvements in orientation to sensory stimuli, although a wide range of other behavioural effects was observed. These included stereotyped exploratory movements (e.g. head waving, walking, sniffing and rearing) similar to those produced in the 6-OHDA treated rats by systemic injection of apomorphine (0.1 mg/kg). These data indicate that 6-OHDA lesions of substantia nigra and ventral midbrain areas do not produce sensory neglect simply by increasing GABA transmission within the nigrotectal pathway. Instead, such an increase in nigrotectal activity may impair production of particular kinds of movement, possibly related to exploratory behaviour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432188
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  • 80
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    The influence of a non-specific stimulator of host resistance on the number and morphological characteristics of macrophages attaching to subcutaneously implanted coverslips in the rat (1981)
    Springer
    Research in experimental medicine 179 (1981), S. 255-259 
    Details
    ISSN: 1433-8580
    Keywords: Stimulator ; Macrophages ; Rat ; Esberitox
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The influence of a preparation (Esberitox) which is claimed to be a non-specific stimulator of host resistance was examined in macrophages attaching to s.c. implanted coverslips in rats. Not only did this preparation significantly increase macrophage numbers but it also very significantly increased the proportion which were stimulated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01851623
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  • 81
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    Alkaline phosphatase isoenzymes in serum of rats during cholestasis (1981)
    Springer
    Research in experimental medicine 179 (1981), S. 269-274 
    Details
    ISSN: 1433-8580
    Keywords: Rat ; Alkaline phosphatase isoenzyme in serum and liver homogenate ; Cholestasis ; Bile duct ligation ; Intoxication with: ANIT, CCL4, phenobarbital
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Alkaline phosphatase isoenzymes (API) in serum of rats during cholestasis are investigated. For comparison different membrane systems in liver are damaged. Proliferation of bile canaliculi, sinusoidal area, and endoplasmic reticulum, respectively, is induced by different toxic conditions. It is found that in cholestasis an API5 in serum arises which is not present in serum of normal rats, but can be detected in normal rat liver. Thus, it is not a de novo synthesis of this API. Under the condition connected with a proliferation of bile canaliculi we find this API5 in serum. Under different conditions without proliferation of bile canaliculi we do not find an increase of this API5. We assume, therefore, that API5 in cholestasis is produced by cells of the bile canaliculi rather than by liver parenchymal cells in the sinusoidal area. No difference is found in intra- or extrahepatic cholestasis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01851625
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  • 82
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    Neuropathy and myopathy in the diaphragm of rats after 12 months of streptozotocin-induced diabetes mellitus (1981)
    Springer
    Acta neuropathologica 55 (1981), S. 11-20 
    Details
    ISSN: 1432-0533
    Keywords: Phrenic nerve ; Diaphragm muscle ; Rat ; Streptozotocin diabetes ; Morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary One year after beginning of the experiment six streptozotocin-injected Wistar rats and six controls were anesthetized and fixed by whole-body perfusion. The diaphragms were isolated and processed for light and electron microscopy. Both the intramuscular branches of the phrenic nerve and the muscle fibers were studied morphologically and morphometrically. Moreover, two diabetic and two control rats were killed by decapitation, the diaphragms were deep-frozen and studied histochemically for myofibrillar ATP-ase. A significant reduction of fiber cross section surface, due to reduction of both myelin and axon surfaces, was found in the phrenic nerves of diabetics. Lesions of Schwann and mesenchymal endoneural cells were the main ultrastructural changes. The diaphragm was much thinner in diabetics than in controls. In diabetics the number of lipid droplets found in red muscle fibers was increased and the white muscle fibers were hypotrophic. These findings were confirmed by the morphometric study. Ultrastructurally, various types of lipid droplets, streaming of Z line, organelle degeneration, invagination of nuclear membrane, and increase in number of satellite cells were found in red fibers of diabetic animals. Disorientation of the triads was the most frequent lesion in white fibers of diabetics. These results demonstrate that both neuropathy and myopathy are present in functionally related nerve and muscle from rats after 12 months of streptozotocin-induced diabetes. Both the dysmetabolic condition and the nervous lesions may have contributed to the muscular changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00691524
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  • 83
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    Experimental corticosteroid myopathy (1981)
    Springer
    Acta neuropathologica 55 (1981), S. 167-172 
    Details
    ISSN: 1432-0533
    Keywords: Myopathy ; Pathology ; Rat ; Steroid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The steroids triamcinolone, dexamethasone, beta-methasone, and cortisone were administered i.p. to adult rats for 14–63 days. The extensor digitorum longus (EDL, white muscle) and soleus (SOL, red muscle) muscles were examined histologically and histochemically. Triamcinolone was the most potent lesion-producing drug. Selective involvement of muscles, and of the fiber types within them was observed: Neerotic changes were seen only in the type 1 fibers of the SOL; atrophic fibers were observed in the type 2 fibers of both the SOL and the EDL.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00691314
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  • 84
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    Effects of several lipidosis-inducing drugs upon the area postrema and adjacent medullary nuclei of adult rats (1981)
    Springer
    Acta neuropathologica 53 (1981), S. 41-50 
    Details
    ISSN: 1432-0533
    Keywords: Giant axon swellings ; Rat ; Drug-induced lipidosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study is concerned with the structure and topographic distribution of axonal alterations in the area postrema and in several adjacent nuclei of adult rats treated with different lipidosis-inducing drugs. The effects of three compounds (chloroquine, quinacrine, perhexiline) that seem to be largely excluded from most parts of the brain except circumventricular organs were compared with a reference compound (chlorphentermine) that has general access to the brain of adult rats. Only chlorphentermine caused generalized axonal alterations (intra-axonal accumulation of polymorphous osmiophilic materials, giant axonal swellings) in all inspected nuclei (area postrema, nucleus gracilis, nucleus tractus solitarii, nucleus nervi hypoglossi, nucleus dorsalis nervi vagi), with nucleus gracilis possessing the most vulnerable axons and axon terminals. The axonal effects of chloroquine were severe only in area postrema and in the closely adjacent neuropil of nucleus gracilis and nucleus tractus solitarii, whereas in the remaining regions axonal alterations were either moderate (lateral portions of nucleus gracilis) or absent. Axonal effects of quinacrine and perhexiline were confined to area postrema. The findings suggest that the topography of the severe axon alterations is greatly dependent on drug distribution. It is concluded that two factors have generally to be considered as responsible for the giant axon swellings found after application of lipidosis-inducing drugs: (a) local drug action upon the axon itself, and (b) lysosomal overloading in the corresponding perikaryon, with factor (a) probably being more potent than factor (b).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697183
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  • 85
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    Morphological and morphometric study of peripheral nerves from rats with streptozotocin-induced diabetes mellitus (1981)
    Springer
    Acta neuropathologica 53 (1981), S. 99-106 
    Details
    ISSN: 1432-0533
    Keywords: Peripheral nerve ; Rat ; Streptozotocin diabetes ; Morphometry ; Morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary One year after beginning of the experiment seven streptozotocin-injected Wistar rats and seven controls were fixed by whole-body perfusion, the nervus radialis was dissected and processed for light and electron microscopy. After light-microscopic study standard photographs of nerve cross sections were measured by means of a semiautomatic image analyzer. The following measurements were obtained: (1) surface of fibers, axons, and myelin sheaths; (2) ratio of myelin to axon surface; and (3) percent of endoneural space. Group means and standard errors were calculated, and cumulated class distributions were made. Ultrathin sections from all animals considered morphometrically were studied qualitatively for ultrastructural changes. The quantitative study revealed in the diabetics reduction of average myelin surface, increase of endoneural space, and reduction of myelin/axon ratio. The main ultrastructural findings were lesions of Schwann and mesenchymal cells, followed by less frequent and less severe changes in axons and endothelium. These results suggest a primary Schwann cell lesion was responsible for the observed myelin reduction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689989
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  • 86
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    Impaired maturation of Purkinje cells in the fetal alcohol syndrome of the rat (1981)
    Springer
    Acta neuropathologica 54 (1981), S. 19-29 
    Details
    ISSN: 1432-0533
    Keywords: Fetal alcohol syndrome ; Rat ; Liquid diet ; Cerebellum ; Purkinje cells ; Rough endoplasmic reticulum ; Metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Alcohol was administed in a vitaminsupplemented liquid diet (Stardit) to Wistar rats 4 weeks before mating and during pregnancy. Of the daily calories 38–40% were supplied by alcohol and by isocaloric sucrose in the controls. Offspring of alcohol drinking dams showed a reduced birth weight and gained weight less rapidly than the controls. On day 3, 4, 7, 12, 17 and 21, experimental animals and controls were perfused for histological and electron microscopic investigations. Morphometric analysis of the cerebella (Fol. 5 and Fol. 8) showed no difference in the number of Purkinje cells. However, on day 7 the Purkinje cell nuclei of experimental pups were significantly smaller. This difference disappeared at day 12. Electron microscopic investigations in the 4, 7, and 12 days old experimental animals revealed a delayed cytoplasmic maturation of Purkinje cells which mainly involved the rough endoplasmic reticulum. At 17 days, there was no difference between the two groups. These data are discussed in relation to alcohol-induced metabolic changes in the brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00691329
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  • 87
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    Changes in peripheral nerves of rats four months after induction of streptozotocin diabetes (1981)
    Springer
    Acta neuropathologica 54 (1981), S. 129-134 
    Details
    ISSN: 1432-0533
    Keywords: Peripheral nerve ; Rat ; Streptozotocin diabetes ; Morphometry ; Morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Eight streptozotocin-injected Wistar rats and eight controls were fixed by whole-body perfusion 4 months after beginning of the experiment, the nervus radialis was dissected and processed for light and electron microscopy. After light-microscopic study standard photographs of nerve cross sections were measured by means of a semiautomatic image analyzer. The following measurements were obtained: (1) surface of fibres, axons, and myelin sheaths, (2) ratio of myelin to axon surface, and (3) percent of endoneural space. Group means and standard deviations were calculated, and cumulated size class distributions were made. Representative nerve specimens from all animals were also studied by electron microscopy. The quantitative study revealed in the diabetics a severe reduction of the average myelin surface, a mild increase of axonal cross section and of endoneural space, a reduction of myelin/axon ratio and a mild reduction in cross section of the nerve. Ultrastructural lesions of minor degree were found in the cytoplasm of Schwann and mesenchymal cells, no lesion was observed in axons. These findings demonstrate the presence of neuropathy 4 months after induction of diabetes and support the pathogenetic role of the Schwann cell in our experimental model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689405
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  • 88
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    Silver staining of the neuronal nucleus in electron microscopy: Nucleolar organization in supraoptic nuclei of the rat hypothalamus (1981)
    Springer
    Anatomy and embryology 163 (1981), S. 265-273 
    Details
    ISSN: 1432-0568
    Keywords: Silver staining ; Neurons ; Nucleolus ; Supraoptic nucleus ; Hypothalamus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present paper describes a simple, efficient method for silver impregnation of supraoptic nuclei of the rat hypothalamus using a modification of the ammoniacal silver technique of Cajal (1903). This procedure, involving a silver-developer sequence in tissue blocks prior to plastic embedding, permits the simultaneous study of Ag-impregnated supraoptic neurons at both light and electron microscopic levels. Visualization of secretory magnocellular neurons impregnated by this technique using the electron microscope reveals a good preservation of nuclear structures. A selective accumulation of silver grains was observed over heterochromatin clumps and nucleoli, which allows the identification of the nucleolar fibrillar centers and also the dense fibrillar component as the main areas involved in the silver reaction. The meaning of such a silver-distribution pattern is discussed in the light of recent ultrastructural and biochemical data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315704
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  • 89
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    The development of the thalamic projections to layer I of the visual cortex of the rat (1981)
    Springer
    Anatomy and embryology 163 (1981), S. 71-75 
    Details
    ISSN: 1432-0568
    Keywords: Visual cortex ; Development ; Projections ; Layer I ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The development of the thalamic afferent projections to layer I of the visual cortex of the albino rat was studied using the retrograde transport of horseradish peroxidase. The results show that the projections to layer I which arise in the “nonspecific” thalamic nuclei (lateral posterior nucleus, posterior complex and ventromedial nucleus) develop earlier than the projection from the “specific” nucleus (dorsal lateral geniculate nucleus).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315771
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  • 90
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    Growth of fresh volumes and spontaneous cell death in the nuclei habenulae of albino rats during ontogenesis (1981)
    Springer
    Anatomy and embryology 161 (1981), S. 419-431 
    Details
    ISSN: 1432-0568
    Keywords: Nuclei habenulae ; Biomathematical Analysis ; Fresh Volume ; Rat ; Spontaneous Nerve Cell Degeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The growth of the nuclei habenulae medialis et lateralis of albino rats is described by monotonically increasing growth curves of fresh volumes during ontogenesis. The nucleus habenulae medialis matures earlier than the nucleus habenulae lateralis in the perinatal period. However, the two nuclei reach their final volume at about the same time. Simultaneous electron microscopic investigation reveals the phenomenon of spontaneous nerve cell degeneration within the nuclei habenulae during ontogenesis in spite of the non-overshooting growth curves for the habenular nuclei.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00316052
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  • 91
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    Development of the visual cortex of rats treated with 6-hydroxydopamine in early life (1981)
    Springer
    Anatomy and embryology 162 (1981), S. 489-492 
    Details
    ISSN: 1432-0568
    Keywords: Visual cortex ; 6-hydroxydopamine ; Development ; Morphology ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The development of the visual cortex was examined in control rats and in littermates whose cortical noradrenergic innervation was removed with 6-hydroxydopamine. Qualitative and quantitative observations revealed no differences in the lamination, cytoarchitecture, cell density and size between the two groups of animals. These results suggest that the number, size, and distribution of cortical neurons are not significantly altered in the absence of noradrenergic afferents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301873
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  • 92
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    Percutaneous absorption of griseofulvin and proquazone in the rat and in isolated human skin (1981)
    Springer
    Archives of dermatological research 271 (1981), S. 275-282 
    Details
    ISSN: 1432-069X
    Keywords: Percutaneous absorption ; Griseofulvin ; Proquazone ; Rat ; Human skin ; Percutane Absorption ; Griseofulvin ; Proquazon ; Ratte ; menschliche Haut
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Salben mit Griseofulvin respektive Proquazon wurden aus Monoglyceriden mittlerer Kettenlänge und einem aprotischen Lösungsmittel, Glycerinformal, hergestellt und auf dem Rücken von Gallefistelratten appliziert. Die percutan resorbierten Mengen sowie die Permeabilitätskonstanten sind für beide Wirkstoffe wesentlich höher nach Applikation der Salben als nach Applikation von einfachen Wirkstofflösungen ohne Monoglyceride. Die Verteilung der markierten Wirkstoffe in Rattenhaut wurde durch Mikroautoradiographie kontrolliert. Die Konzentrationen der Wirkstoffe in den einzelnen Schichten von menschlicher Haut sowie die mittleren Penetrationsraten wurden 16 h nach Applikation der Salben auf isolierte menschliche Haut bestimmt. Monoglyceride mittlerer Kettenlänge erhöhen die Permeabilität des Stratum corneum für gelöste Wirkstoffe wesentlich.
    Notes: Summary Ointments containing griseofulvin and proquazone, respectively, were made up of monoglycerides of medium chain length and an aprotic solvent, glycerinformal. The ointments were applied topically on the back of bile cannulated rats. The total amount absorbed percutaneously and the permeability constants of both drugs were considerably higher for the ointments than for simple solutions of the drugs without monoglycerides. Distribution of the labeled drugs in rat skin has been demonstrated by microautoradiography. Concentrations of the drugs in the different layers of human skin together with the medium flow rates have been determined 16h after administration of the ointments onto isolated human skin. Monoglycerides of medium chain length enhance significantly the permeability of the stratum corneum for solutes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409456
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    Immunochemical properties of antigens present on immature erythrocytes from mouse and rat (1981)
    Springer
    Annals of hematology 43 (1981), S. 361-366 
    Details
    ISSN: 1432-0584
    Keywords: Immunoprecipitation ; Immature antigens ; Mouse ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Rabbit antisera directed against erythrocytes from anemic mice or from newborn rats, once absorbed on homologous normal adult erythrocytes, recognize antigens present respectively on immature erythrocytes from anemic adult mice or rats (Im M and Im R antigens). Using iodinated immature erythrocytes from both species, homologous sera precipitated two populations of antigens showing 230,000 D and 95,000 D molecular weights. Im M antigens (230,000 and 95,000 D) were partially precipitated using anti-Im R serum. After total absorption of the sample by anti-Im R serum, both 230,000 and 95,000 D antigens were still immunoprecipitated using anti-Im M serum. Similar results were obtained using Im R antigens and anti-Im M serum then anti-Im R serum. This demonstrates that some Im specificities are common to rat and mouse while others, showing identical molecular weights, are species-specific.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00320314
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  • 94
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    Musculi longus capitis et splenius der Ratte und innervierende Motoneurone (1981)
    Springer
    Acta neuropathologica 53 (1981), S. 267-273 
    Details
    ISSN: 1432-0533
    Keywords: Rat ; Neck muscles ; Motoneurons ; Dendrites ; HRP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The nuclei for the nerves of a dorsal (m. splenius) and a ventral (m. longus capitis) neck muscle of the rat were retrogradely labeled by applying horseradish peroxidase (HRP) to the respective cut muscle nerves. Motoneurons of both muscles were analyzed for their localization, diameter of perikarya, and area of dendritic arborization. The nucleus of m. longus capitis is situated dorsomedially, the nucleus of m. splenius ventromedially within the ventral horn. Thus, the relative positions of the two nuclei are inverse to those of their muscles, with the more ventral nucleus innervating the more dorsal muscle. In both nuclei the areas of dendritic arborization are very large, extending into the nuclei of other neck muscles, and also into the ipsilateral anterior funiculus. In addition, m. longus capitis motoneurons were found to send dendrites into the contralateral ventral horn, reaching the nucleus of the contralateral muscle. The size distribution of perikarya is bimodal for m. longus capitis motoneurons, but only unimodal in the case of m. splenius.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690368
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  • 95
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    Nerve fibre degeneration of the central and peripheral nervous systems in severe protein deprivation in rats (1981)
    Springer
    Acta neuropathologica 54 (1981), S. 121-127 
    Details
    ISSN: 1432-0533
    Keywords: Rat ; Protein deprivation ; Nerve fibre degeneration ; Central nervous system ; Peripheral nervous system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Knowledge from previous reports that kwashiorkor in man may lead to nerve fibre degeneration prompted this study on rats. The rats were subjected to severe protein deprivation from 6 weeks of age. Protein deprivation was achieved by feeding the rats ad lib with a diet containing only 1.5% protein. Control rats received an iso-caloric diet with 14% protein. The vitamin content in both diets was well above normal requirements. In relation to body weight the protein-deprived rats did not consume less food than the control rats. Protein deprivation resulted in stunted body growth, markedly reduced values of serum albumin, and changes in the fur accompanied by areas of alopecia. Furthermore, the protein-deprived rats showed degeneration of nerve fibres in the medial parts of the posterior columns of the cervical but not the sacral part of the spinal cord and nerve fibre degeneration in the distal but not the proximal parts of the longitudinal tail nerves. Teased nerve fibre preparations of the tail nerves revealed changes consistent with the Wallerian type of degeneration. It is concluded that severe protein deprivation in young rats may lead to a “dying-back” type of neuropathy in the central and peripheral nervous systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689404
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  • 96
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    Experimental brain tumors and edema in rats (1981)
    Springer
    Acta neuropathologica 55 (1981), S. 105-111 
    Details
    ISSN: 1432-0533
    Keywords: Brain tumor ; Brain edema ; Histology ; Cytology ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In this study an experimental intracerebral tumor has been investigated with special consideration of structures, which may be involved in edema production and/or resolution. For this purpose a cloned tumor cell line (RG1 2.2) has been injected stereotactically into the brain of BD-IX rats. The tumor has some characteristics in common with low differentiated oligodendroglioma in men. A honcycomb architecture may be seen in the center of the tumor. It is built up by rounded or elongated cells, which can be impregnated in parts. In the central area, cells exhibit a volominous digestive apparatus, composed of dictyosomes, vesicles, and some vacuoles with a membranaceous or homogeneous content. Tumor cells in the periphery show large processes and a small digestive apparatus. The sinusoidal tumor vessels are composed of an endothelium with many vesicles but no openings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00699235
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  • 97
    Electronic Resource
    Electronic Resource
    Effect of vitamin D deficiency on urinary excretion of connective tissue derivatives (hydroxyproline and glycosaminoglycans) in rats (1981)
    Springer
    Calcified tissue international 33 (1981), S. 177-180 
    Details
    ISSN: 1432-0827
    Keywords: Connective Tissue ; Vitamin D deficiency ; Hydroxyproline excretion ; Glycosaminoglycan excretion ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The urinary excretion of two connective tissue metabolites was studied in both control and vitamin D deficient rats. Hydroxyproline (HyPRO) excretion was determined after 2, 13 and 22 months (experiment I). It decreased with aging in animals receiving the control diet. On the contrary, this excretion increased as a function of age in vitamin D deficient animals. At the age of 22 months, HyPRO excretion was respectively 31 and 1708 µg a day in control and deficient animals. HyPRO and glycosaminoglycans (GAG) excretion was measured on a group of both control and vitamin D deficient rats at the age of 21 months (experiment II). These results confirm the high excretion of HyPRO in deficient animals. On the contrary, the GAG excretion was higher in control animals than in deficient ones, the mean excretion being respectively 412 and 234 µg a day.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02409432
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  • 98
    Electronic Resource
    Electronic Resource
    Effects of chronic protein deficiency on skeletal development of young rats (1981)
    Springer
    Calcified tissue international 33 (1981), S. 223-231 
    Details
    ISSN: 1432-0827
    Keywords: Protein deficiency ; Bone formation ; Skeletal development ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Protein deficiency was produced by freely feeding young rats a 1% lactalbumin diet for 12 weeks in order to study the effects of protein-calorie malnutrition on skeletal development. During the experiment the food and caloric intake and weight of the experimental animals decreased, while those parameters of the control animals progressively increased. However, when gross caloric intake was expressed as a function of the metabolic size of the animal, the caloric consumption was similar for both groups of animals. The protein-deficient animals exhibited micro-radiographic and histological features of an abnormal pattern of endochondral bone formation. Appositional bone growth, as determined by the daily appositional rate and the percentage of endosteal surfaces undergoing active bone formation, was significantly decreased in these animals, as was the percentage of periosteal surfaces exhibiting resorption. Both chemical analyses of the whole bone and electron probe microanalysis in the specific area of actively calcifying bone revealed no significant differences between the mineral content of control and protein-deficient animals. This study distinguishes the effects of protein deficiency from that of combined protein-calorie deprivation and demonstrates that the abnormal skeletal development observed was the result of a decrease in the quantity of bone formed rather than an altered mineral content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02409441
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  • 99
    Electronic Resource
    Electronic Resource
    Cytochemical studies on the ferritin-containing vesicles of the rat incisor ameloblasts with special reference to the acid phosphatase activity (1981)
    Springer
    Calcified tissue international 33 (1981), S. 51-55 
    Details
    ISSN: 1432-0827
    Keywords: Rat ; Incisor ; Amelogenesis ; Acid phosphatase ; Ferritin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Acid phosphatase was localized in rat incisor ameloblasts without prior decalcification. Whenβ-glycerophosphate was used as the substrate, an intense reaction was observed in the supranuclear region of the secretory ameloblasts. But the reaction was dramatically reduced at the transitional stage and was very weak in the maturation ameloblasts. Whenp-nitrophenylphosphate was the substrate, the reaction product was consistently seen in the Golgi cisternae and the vesicular components of the ameloblasts at all stages of enamel development. These observations suggest that there are two acid phosphatases in ameloblasts. One is in the secretory ameloblasts and the other in the transition and maturation ameloblasts. X-ray micro-analyses for Fe and Pb showed that Fe and acid phosphatase were in the ferritin-containing vesicles at the later stage of enamel maturation. This evidence suggests that ferritin is digested in these vesicles for the release of the Fe pigment to the enamel. An increase in the number of intercellular bridges between ameloblasts was correlated with the dramatic decrease in height of ameloblasts at the pigment release stage. The ameloblast membranes were acid phosphatase positive at the intercellular bridges whenp-nitrophenylphosphate was the substrate. This activity may be involved in the reduction in the surface area of the ameloblast membranes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02409412
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  • 100
    Electronic Resource
    Electronic Resource
    The effects of neural stalk stimulation upon firing patterns in rat supraoptic neurones (1981)
    Springer
    Experimental brain research 41 (1981), S. 135-145 
    Details
    ISSN: 1432-1106
    Keywords: Supraoptic nucleus ; Rat ; Antidromic ; Phasic ; Recurrent inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Antidromically identified neurones were recorded from the supraoptic neucleus of urethane-anaesthetised rats. In test periods of about 10 min, each recorded action potential was followed 1 ms later by a shock to the neural stalk. In phasically firing cells, this stimulation consistently modified the observed firing pattern: burst length was shortened but intraburst activity was unchanged. The stimulation invaded most supraoptic neurones antidromically, but antidromic spikes evoked in the recorded neurone were extinguished by collision. Thus, the observed changes in firing pattern were probably the consequence of interaction between the recorded unit and other neurones projecting to the neural stalk — most probably other supraoptic neurones. The behaviour of continuously firing supraoptic neurones was studied following single shocks and following trains of shocks. The results suggest that the widely reported evidence for recurrent inhibition in the rat supraoptic nucleus has been misinterpreted, and that inhibition cannot be demonstrated in most supraoptic neurones following single shocks to the neural stalk. However, the experiments using trains of shocks produced evidence consistent with a complex interaction between magnocellular neurosecretory cells involving both excitation and inhibition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236603
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