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  • ddc:510  (41)
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  • 2015-2019
  • 2005-2009  (41)
  • 1985-1989
  • 1970-1974  (837)
  • 1800-1809
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  • 1
    Publication Date: 2020-08-05
    Description: Das heutige Leben ist durchdrungen von komplexen Technologien. Ohne Kommunikationsnetze, Internet, Mobilfunk, Logistik, Verkehrstechnik, medizinische Apparate, etc. könnte die moderne Gesellschaft nicht funktionieren. Fast alle dieser Technologien haben einen hohen Mathematikanteil. Der "normale Bürger"' weiss davon nichts, der Schulunterricht könnte dem ein wenig abhelfen. Einige mathematische Aspekte dieser Technologien sind einfach und sogar spielerisch intuitiv zugänglich. Solche Anwendungen, die zusätzlich noch der Lebensumwelt der Schüler zugehören, können dazu genutzt werden, die mathematische Modellierung, also die mathematische Herangehensweise an die Lösung praktischer Fragen, anschaulich zu erläutern. Gerade in der diskreten Mathematik können hier, quasi "nebenbei" mathematische Theorien erarbeitet und Teilaspekte (Definitionen, Fragestellungen, einfache Sachverhalte) durch eigenständiges Entdecken der Schüler entwickelt werden. Wir beginnen mit einigen Beispielen.
    Keywords: ddc:510
    Language: German
    Type: reportzib , doc-type:preprint
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  • 2
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    Publication Date: 2020-08-05
    Description: Den kürzesten Weg in einem Graphen zu finden ist ein klassisches Problem der Graphentheorie. Über einen Vortrag zu diesem Thema beim Tag der Mathematik 2007 von R. Borndörfer kam ich in Kontakt mit dem Konrad-Zuse-Zentrum (ZIB), das sich u.a. mit Wegeoptimierung beschäftigt. Ein Forschungsschwerpunkt dort ist im Rahmen eines Projekts zur Chipverifikation das Zählen von Lösungen, das, wie wir sehen werden, eng mit dem Zählen von Wegen zusammenhängt. Anhand von zwei Fragen aus der Graphentheorie soll diese Facharbeit unterschiedliche Lösungsmethoden untersuchen. Wie bestimmt man den kürzesten Weg zwischen zwei Knoten in einem Graphen und wie findet man alle möglichen Wege? Nach einer Einführung in die Graphentheorie und einer Konkretisierung der Probleme wird zunächst für beide eine Lösung mit auf Graphen basierenden Algorithmen vorgestellt. Während der Algorithmus von Dijkstra sehr bekannt ist, habe ich für das Zählen von Wegen einen eigenen Algorithmus auf der Basis der Tiefensuche entwickelt. Im zweiten Teil der Arbeit wird das Konzept der ganzzahligen Programmierung vorgestellt und die Lösungsmöglichkeiten für Wegeprobleme, die sich darüber ergeben. Schließlich wurden die vorgestellten Algorithmen am Beispiel des S- und U-Bahnnetzes von Berlin implementiert und mit Programmen, die die gleichen Fragen über ganzzahlige Programmierung lösen, verglichen.
    Keywords: ddc:510
    Language: German
    Type: reportzib , doc-type:preprint
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  • 3
    Publication Date: 2016-06-09
    Description: This paper is intended to be a first step towards the continuous dependence of dynamical contact problems on the initial data as well as the uniqueness of a solution. Moreover, it provides the basis for a proof of the convergence of popular time integration schemes as the Newmark method. We study a frictionless dynamical contact problem between both linearly elastic and viscoelastic bodies which is formulated via the Signorini contact conditions. For viscoelastic materials fulfilling the Kelvin-Voigt constitutive law, we find a characterization of the class of problems which satisfy a perturbation result in a non-trivial mix of norms in function space. This characterization is given in the form of a stability condition on the contact stresses at the contact boundaries. Furthermore, we present perturbation results for two well-established approximations of the classical Signorini condition: The Signorini condition formulated in velocities and the model of normal compliance, both satisfying even a sharper version of our stability condition.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 4
    Publication Date: 2020-08-05
    Description: Most data networks nowadays use shortest path protocols to route the traffic. Given administrative routing lengths for the links of the network, all data packets are sent along shortest paths with respect to these lengths from their source to their destination. In this paper, we present an integer programming algorithm for the minimum congestion unsplittable shortest path routing problem, which arises in the operational planning of such networks. Given a capacitated directed graph and a set of communication demands, the goal is to find routing lengths that define a unique shortest path for each demand and minimize the maximum congestion over all links in the resulting routing. We illustrate the general decomposition approach our algorithm is based on, present the integer and linear programming models used to solve the master and the client problem, and discuss the most important implementational aspects. Finally, we report computational results for various benchmark problems, which demonstrate the efficiency of our algorithm.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 5
    Publication Date: 2020-12-15
    Description: This paper introduces the "line connectivity problem", a generalization of the Steiner tree problem and a special case of the line planning problem. We study its complexity and give an IP formulation in terms of an exponential number of constraints associated with "line cut constraints". These inequalities can be separated in polynomial time. We also generalize the Steiner partition inequalities.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 6
    Publication Date: 2020-08-05
    Description: Testing is the process of stimulating a system with inputs in order to reveal hidden parts of the system state. In the case of non-deterministic systems, the difficulty arises that an input pattern can generate several possible outcomes. Some of these outcomes allow to distinguish between different hypotheses about the system state, while others do~not. In this paper, we present a novel approach to find, for non-deterministic systems modeled as constraints over variables, tests that allow to distinguish among the hypotheses as good as possible. The idea is to assess the quality of a test by determining the ratio of distinguishing (good) and not distinguishing (bad) outcomes. This measure refines previous notions proposed in the literature on model-based testing and can be computed using model counting techniques. We propose and analyze a greedy-type algorithm to solve this test optimization problem, using existing model counters as a building block. We give preliminary experimental results of our method, and discuss possible improvements.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 7
    Publication Date: 2021-08-05
    Description: Starting with the description of the Traveling Salesmen Problem formulation as given by van Vyve and Wolsey in the article Approximate extended formulations'', we investigate the effects of small variations onto the performance of contemporary mixed integer programming solvers. We will show that even minor changes in the formulation of the model can result in performance difference of more than a factor of 1000. As the results show it is not obvious which changes will result in performance improvements and which not.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 8
    Publication Date: 2022-03-14
    Description: Orbitopes can be used to handle symmetries which arise in integer programming formulations with an inherent assignment structure. We investigate the detection of symmetries appearing in this approach. We show that detecting so-called orbitopal symmetries is graph-isomorphism hard in general, but can be performed in linear time if the assignment structure is known.
    Keywords: ddc:510
    Language: English
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  • 9
    Publication Date: 2019-01-29
    Description: Regional hyperthermia is a cancer therapy aiming at heating tumors using phased array applicators. This article provides an overview over current mathematical challenges of delivering individually optimal treatments. The focus is on therapy planning and identification of technical as well as physiological quantities from MR thermometry measurements.
    Keywords: ddc:510
    Language: English
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  • 10
    Publication Date: 2019-05-10
    Description: Reasons for the failure of adaptive methods to deliver improved efficiency when integrating monodomain models for myocardiac excitation are discussed. Two closely related techniques for reducing the computational complexity of linearly implicit integrators, deliberate sparsing and splitting, are investigated with respect to their impact on computing time and accuracy.
    Keywords: ddc:510
    Language: English
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  • 11
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    Publication Date: 2020-08-05
    Description: We investigate the computation of periodic timetables for public transport by mixed integer programming. After introducing the problem, we describe two mathematical models for periodic timetabling, the PERIODIC EVENT SCHEDULING PROBLEM (PESP) and the QUADRATIC SEMI-ASSIGNMENT PROBLEM. Specifically, we give an overview of existing integer programming (IP) formulations for both models. An important contribution of our work are new IP formulations for the PESP based on time discretization. We provide an analytical comparison of these formulations and describe different techniques that allow a more efficient solution by mixed integer programming. In a preliminary computational study, on the basis of standard IP solvers, we compare different formulations for computing periodic timetables. Our results justify a further investigation of the time discretization approach. Typically the timetable is optimized for the current traffic situation. The main difficulty with this approach is that after introducing the new timetable the passengers’ travel behavior may differ from that assumed for the computation. Motivated by this problem, we examine an iterative timetabling procedure that is a combination of timetable computation and passenger routing. We discuss the algorithmic issues of the passenger routing and study properties of the computed timetables. Finally, we confirm our theoretical results on the basis of an own implementation.
    Description: Wir untersuchen die Berechnung von Taktfahrplänen für den öffentlichen Verkehr mit gemischt-ganzzahliger Programmierung (MIP). Im Anschluss an die Problembeschreibung, stellen wir zwei mathematische Modellierungen vor, das PERIODIC EVENT SCHEDULING PROBLEM (PESP) und das QUADRATIC SEMI-ASSIGNMENT PROBLEM. Wichtiger Bestandteil ist ein Überblick über existierende ganzzahlige Formulierungen beider Modelle. Wir entwickeln neue ganzzahlige Formulierungen für das PESP auf der Basis von Zeitdiskretisierung. Diese werden analytisch miteinander verglichen und wir beschreiben verschiedene Techniken, die eine effizientere Lösung der Formulierungen mit gemischt-ganzzahliger Programmierung ermöglichen. In einer ersten Rechenstudie, unter Verwendung gängiger MIP-Löser, vergleichen wir verschiedene ganzzahlige Formulierungen zur Berechnung von Taktfahrplänen. Unsere Ergebnisse rechtfertigen eine weitere Untersuchung des Zeitdiskretisierungsansatzes. In der Regel werden Fahrpläne mit Bezug auf die gegenwärtige Verkehrssituation optimiert. Dies birgt jedoch folgendes Problem. Wenn der neue Fahrplan eingeführt wird, ist es möglich, dass die Passagiere ein anderes Fahrverhalten zu Tage legen, als für die Berechnung des Fahrplans angenommen wurde. Vor diesem Hintergrund behandeln wir ein iteratives Verfahren zur Berechnung von Taktfahrplänen. Dieses ist eine Kombination aus Fahrplanberechnung und Passagierrouting. Neben den algorithmischen Details des Passagierroutings untersuchen wir Eigenschaften der berechneten Fahrpläne. Abschließend bestätigen wir unsere theoretischen Ergebnisse auf Grundlage einer eigenen Implementierung des Verfahrens.
    Keywords: ddc:510
    Language: English
    Type: masterthesis , doc-type:masterThesis
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  • 12
    Publication Date: 2020-08-05
    Description: This paper describes several experiments to explore the options for solving a class of mixed integer nonlinear programming problems that stem from a real-world mine production planning project. The only type of nonlinear constraints in these problems are bilinear equalities involving continuous variables, which enforce the ratios between elements in mixed material streams. A branch-and-bound algorithm to handle the integer variables has been tried in another project. However, this branch-and-bound algorithm is not effective for handling the nonlinear constraints. Therefore state-of-the-art nonlinear solvers are utilized to solve the resulting nonlinear subproblems in this work. The experiments were carried out using the NEOS server for optimization. After finding that current nonlinear programming solvers seem to lack suitable preprocessing capabilities, we preprocess the instances beforehand and use an heuristic approach to solve the nonlinear subproblems. In the appendix, we explain how to add a polynomial constraint handler that uses IPOPT as embedded nonlinear programming solver for the constraint programming framework SCIP. This is one of the crucial steps for implementing our algorithm in SCIP. We briefly described our approach and give an idea of the work involved.
    Keywords: ddc:510
    Language: English
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  • 13
    Publication Date: 2020-08-05
    Description: Dieser kurze Aufsatz zur Algorithmengeschichte ist Eberhard Knobloch, meinem Lieblings-Mathematikhistoriker, zum 65. Geburtstag gewidmet. Eberhard Knobloch hat immer, wenn ich ihm eine historische Frage zur Mathematik stellte, eine Antwort gewusst – fast immer auch sofort. Erst als ich mich selbst ein wenig und dazu amateurhaft mit Mathematikgeschichte beschäftigte, wurde mir bewusst, wie schwierig dieses „Geschäft“ ist. Man muss nicht nur mehrere (alte) Sprachen beherrschen, sondern auch die wissenschaftliche Bedeutung von Begriffen und Symbolen in früheren Zeiten kennen. Man muss zusätzlich herausfinden, was zur Zeit der Entstehung der Texte „allgemeines Wissen“ war, insbesondere, was seinerzeit gültige Beweisideen und -schritte waren, und daher damals keiner präzisen Definition oder Einführung bedurfte. Es gibt aber noch eine Steigerung des historischen Schwierigkeitsgrades: Algorithmengeschichte. Dies möchte ich in diesem Artikel kurz darlegen in der Hoffnung, dass sich Wissenschaftshistoriker dieses Themas noch intensiver annehmen, als sie das bisher tun. Der Grund ist, dass heute Algorithmen viele Bereiche unserer Alltagswelt steuern und unser tägliches Leben oft von funktionierenden Algorithmen abhängt. Daher wäre eine bessere Kenntnis der Algorithmengeschichte von großem Interesse.
    Keywords: ddc:510
    Language: German
    Type: reportzib , doc-type:preprint
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  • 14
    Publication Date: 2016-06-09
    Description: We consider first order optimality conditions for state constrained optimal control problems. In particular we study the case where the state equation has not enough regularity to admit existence of a Slater point in function space. We overcome this difficulty by a special transformation. Under a density condition we show existence of Lagrange multipliers, which have a representation via measures and additional regularity properties.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 15
    Publication Date: 2016-06-09
    Description: The enormous time lag between fast atomic motion and complex pro- tein folding events makes it almost impossible to compute molecular dy- namics on a high resolution. A common way to tackle this problem is to model the system dynamics as a Markov process. Yet for large molec- ular systems the resulting Markov chains can hardly be handled due to the curse of dimensionality. Coarse graining methods can be used to re- duce the dimension of a Markov chain, but it is still unclear how far the coarse grained Markov chain resembles the original system. In order to answer this question, two different coarse-graining methods were analysed and compared: a classical set-based reduction method and an alternative subspace-based approach, which is based on membership vectors instead of sets. On the basis of a small toy system, it could be shown, that in con- trast to the subset-based approach, the subspace-based reduction method preserves the Markov property as well as the essential dynamics of the original system.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 16
    Publication Date: 2021-02-19
    Description: Line planning is an important step in the strategic planning process of a public transportation system. In this paper, we discuss an optimization model for this problem in order to minimize operation costs while guaranteeing a certain level of quality of service, in terms of available transport capacity. We analyze the problem for path and tree network topologies as well as several categories of line operation that are important for the Quito Trolebus system. It turns out that, from a computational complexity worst case point of view, the problem is hard in all but the most simple variants. In practice, however, instances based on real data from the Trolebus System in Quito can be solved quite well, and significant optimization potentials can be demonstrated.
    Keywords: ddc:510
    Language: English
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  • 17
    Publication Date: 2020-08-05
    Description: It is well known that competitive analysis yields too pessimistic results when applied to the paging problem and it also cannot make a distinction between many paging strategies. Many deterministic paging algorithms achieve the same competitive ratio, ranging from inefficient strategies as flush-when-full to the good performing least-recently-used (LRU). In this paper, we study this fundamental online problem from the viewpoint of stochastic dominance. We show that when sequences are drawn from distributions modelling locality of reference, LRU is stochastically better than any other online paging algorithm.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 18
    Publication Date: 2020-12-15
    Description: Die Angebotsplanung im öffentlichen Nahverkehr umfasst die Aufgaben der Netz-, Linien-,Fahr- und Preisplanung. Wir stellen zwei mathematische Optimierungsmodelle zur Linien- und Preisplanung vor. Wir zeigen anhand von Berechnungen für die Verkehrsbetriebe in Potsdam(ViP), dass sich damit komplexe Zusammenhänge quantitativ analysieren lassen. Auf diese Weise untersuchen wir die Auswirkungen von Freiheitsgraden auf die Konstruktion von Linien und die Wahl von Reisewegen der Passagiere, Abhängigkeiten zwischen Kosten und Reisezeiten sowie den Einfluss verschiedener Preissysteme auf Nachfrage und Kostendeckung.
    Keywords: ddc:510
    Language: German
    Type: reportzib , doc-type:preprint
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  • 19
    Publication Date: 2022-03-14
    Description: This article introduces constraint integer programming (CIP), which is a novel way to combine constraint programming (CP) and mixed integer programming (MIP) methodologies. CIP is a generalization of MIP that supports the notion of general constraints as in CP. This approach is supported by the CIP framework SCIP, which also integrates techniques from SAT solving. SCIP is available in source code and free for non-commercial use. We demonstrate the usefulness of CIP on two tasks. First, we apply the constraint integer programming approach to pure mixed integer programs. Computational experiments show that SCIP is almost competitive to current state-of-the-art commercial MIP solvers. Second, we employ the CIP framework to solve chip design verification problems, which involve some highly non-linear constraint types that are very hard to handle by pure MIP solvers. The CIP approach is very effective here: it can apply the full sophisticated MIP machinery to the linear part of the problem, while dealing with the non-linear constraints by employing constraint programming techniques.
    Keywords: ddc:510
    Language: English
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  • 20
    Publication Date: 2016-06-09
    Description: An extended mathematical framework for barrier methods for state constrained optimal control compared to [Schiela, ZIB-Report 07-07] is considered. This allows to apply the results derived there to more general classes of optimal control problems, in particular to boundary control and finite dimensional control.
    Keywords: ddc:510
    Language: English
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  • 21
    Publication Date: 2021-08-05
    Description: In the recent years there has been tremendous progress in the development of algorithms to find optimal solutions for integer programs. In many applications it is, however, desirable (or even necessary) to generate all feasible solutions. Examples arise in the areas of hardware and software verification and discrete geometry. In this paper, we investigate how to extend branch-and-cut integer programming frameworks to support the generation of all solutions. We propose a method to detect so-called unrestricted subtrees, which allows us to prune the integer program search tree and to collect several solutions simultaneously. We present computational results of this branch-and-count paradigm which show the potential of the unrestricted subtree detection.
    Keywords: ddc:510
    Language: English
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  • 22
    Publication Date: 2020-08-05
    Description: Edmonds showed that the so-called rank inequalities and the nonnegativity constraints provide a complete linear description of the matroid polytope. By essentially adding Grötschel's cardinality forcing inequalities, we obtain a complete linear description of the cardinality constrained matroid polytope which is the convex hull of the incidence vectors of those independent sets that have a feasible cardinality. Moreover, we show how the separation problem for the cardinality forcing inequalities can be reduced to that for the rank inequalities. We also give necessary and sufficient conditions for a cardinality forcing inequality to be facet defining.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 23
    Publication Date: 2020-08-05
    Description: The paper describes a method for solution of very large overdetermined algebraic polynomial systems on an example that appears from a classification of all integrable 3-dimensional scalar discrete quasilinear equations $Q_3=0$ on an elementary cubic cell of the lattice ${\mathbb Z}^3$. The overdetermined polynomial algebraic system that has to be solved is far too large to be formulated. A probing' technique which replaces independent variables by random integers or zero allows to formulate subsets of this system. An automatic alteration of equation formulating steps and equation solving steps leads to an iteration process that solves the computational problem.
    Keywords: ddc:510
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  • 24
    Publication Date: 2020-08-05
    Description: An algorithmic method using conservation law multipliers is introduced that yields necessary and sufficient conditions to find invertible mappings of a given nonlinear PDE to some linear PDE and to construct such a mapping when it exists. Previous methods yielded such conditions from admitted point or contact symmetries of the nonlinear PDE. Through examples, these two linearization approaches are contrasted.
    Keywords: ddc:510
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  • 25
    Publication Date: 2021-02-26
    Description: We classify all integrable 3-dimensional scalar discrete affine linear equations $Q_3=0$ on an elementary cubic cell of the lattice ${\mathbb Z}^3$. An equation $Q_3=0$ %of such form is called integrable if it may be consistently imposed on all $3$-dimensional elementary faces of the lattice ${\mathbb Z}^4$. Under the natural requirement of invariance of the equation under the action of the complete group of symmetries of the cube we prove that the only ontrivial(non-linearizable) integrable equation from this class is the well-known dBKP-system.
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  • 26
    Publication Date: 2020-12-11
    Description: The article describes the online mathematics test {\tt http://lie.math.brocku.ca/mathtest}, its typical applications and experiences gathered.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 27
    Publication Date: 2020-08-05
    Description: We introduce (TTPlib), a data library for train timetabling problems that can be accessed at http://ttplib.zib.de. In version 1.0, the library contains data related to 50 scenarios. Most instances result from the combination of macroscopic railway networks and several train request sets for the German long distance area containing Hannover, Kassel and Fulda, short denoted by Ha-Ka-Fu. In this paper, we introduce the data concepts of TTPlib, describe the scenarios included in the library and provide a free visualization tool TraVis.
    Keywords: ddc:510
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  • 28
    Publication Date: 2020-08-05
    Description: The purpose of this paper is twofold. An immediate practical use of the presented algorithm is its applicability to the parametric solution of underdetermined linear ordinary differential equations (ODEs) with coefficients that are arbitrary analytic functions in the independent variable. A second conceptual aim is to present an algorithm that is in some sense dual to the fundamental Euclids algorithm, and thus an alternative to the special case of a Gr\"{o}bner basis algorithm as it is used for solving linear ODE-systems. In the paper Euclids algorithm and the new dual version' are compared and their complementary strengths are analysed on the task of solving underdetermined ODEs. An implementation of the described algorithm is interactively accessible at http://lie.math.brocku.ca/crack/uode.
    Keywords: ddc:510
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  • 29
    Publication Date: 2020-08-05
    Description: This paper proposes a new method for probabilistic analysis of online algorithms that is based on the notion of stochastic dominance. We develop the method for the Online Bin Coloring problem introduced by Krumke et al. Using methods for the stochastic comparison of Markov chains we establish the strong result that the performance of the online algorithm GreedyFit is stochastically dominated by the performance of the algorithm OneBin for any number of items processed. This result gives a more realistic picture than competitive analysis and explains the behavior observed in simulations.
    Keywords: ddc:510
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  • 30
    Publication Date: 2020-12-15
    Description: The optimization of fare systems in public transit allows to pursue objectives such as the maximization of demand, revenue, profit, or social welfare. We propose a non-linear optimization approach to fare planning that is based on a detailed discrete choice model of user behavior. The approach allows to analyze different fare structures, optimization objectives, and operational scenarios involving, e.g., subsidies. We use the resulting models to compute optimized fare systems for the city of Potsdam, Germany.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 31
    Publication Date: 2022-03-14
    Description: Pseudo-Boolean problems generalize SAT problems by allowing linear constraints and a linear objective function. Different solvers, mainly having their roots in the SAT domain, have been proposed and compared,for instance, in Pseudo-Boolean evaluations. One can also formulate Pseudo-Boolean models as integer programming models. That is,Pseudo-Boolean problems lie on the border between the SAT domain and the integer programming field. In this paper, we approach Pseudo-Boolean problems from the integer programming side. We introduce the framework SCIP that implements constraint integer programming techniques. It integrates methods from constraint programming, integer programming, and SAT-solving: the solution of linear programming relaxations, propagation of linear as well as nonlinear constraints, and conflict analysis. We argue that this approach is suitable for Pseudo-Boolean instances containing general linear constraints, while it is less efficient for pure SAT problems. We present extensive computational experiments on the test set used for the Pseudo-Boolean evaluation 2007. We show that our approach is very efficient for optimization instances and competitive for feasibility problems. For the nonlinear parts, we also investigate the influence of linear programming relaxations and propagation methods on the performance. It turns out that both techniques are helpful for obtaining an efficient solution method.
    Keywords: ddc:510
    Language: English
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  • 32
    Publication Date: 2020-08-05
    Description: Millionen von Menschen werden allein in Deutschland täglich von Bussen, Bahnen und Flugzeugen transportiert. Der öffentliche Personenverkehr (ÖV) ist von großer Bedeutung für die Lebensqualität einzelner aber auch für die Leistungsfähigkeit ganzer Regionen. Qualität und Effizienz von ÖV-Systemen hängen ab von politischen Rahmenbedingungen (staatlich geplant, wettbewerblich organisiert) und der Eignung der Infrastruktur (Schienensysteme, Flughafenstandorte), vom vorhandenen Verkehrsangebot (Fahr- und Flugplan), von der Verwendung angemessener Technologien (Informations-, Kontroll- und Buchungssysteme) und dem bestmöglichen Einsatz der Betriebsmittel (Energie, Fahrzeuge und Personal). Die hierbei auftretenden Entscheidungs-, Planungs- und Optimierungsprobleme sind z.T. gigantisch und "schreien" aufgrund ihrer hohen Komplexität nach Unterstützung durch Mathematik. Dieser Artikel skizziert den Stand und die Bedeutung des Einsatzes von Mathematik bei der Planung und Durchführung von öffentlichem Personenverkehr, beschreibt die bestehenden Herausforderungen und regt zukunftsweisende Maßnahmen an.
    Keywords: ddc:510
    Language: German
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  • 33
    Publication Date: 2019-05-10
    Description: Pulse thermography of concrete structures is used in civil engineering for detecting voids, honeycombing and delamination. The physical situation is readily modeled by Fourier's law. Despite the simplicity of the PDE structure, quantitatively realistic numerical 3D simulation faces two major obstacles. First, the short heating pulse induces a thin boundary layer at the heated surface which encapsulates all information and therefore has to be resolved faithfully. Even with adaptive mesh refinement techniques, obtaining useful accuracies requires an unsatisfactorily fine discretization. Second, bulk material parameters and boundary conditions are barely known exactly. We address both issues by a semi-analytic reformulation of the heat transport problem and by parameter identification. Numerical results are compared with measurements of test specimens.
    Keywords: ddc:510
    Language: English
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  • 34
    Publication Date: 2016-06-09
    Description: In this paper we are concerned with the application of interior point methods in function space to gradient constrained optimal control problems, governed by partial differential equations. We will derive existence of solutions together with first order optimality conditions. Afterwards we show continuity of the central path, together with convergence rates depending on the interior point parameter.
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    Language: English
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  • 35
    Publication Date: 2016-06-09
    Description: We consider an interior point method in function space for PDE constrained optimal control problems with state constraints. Our emphasis is on the construction and analysis of an algorithm that integrates a Newton path-following method with adaptive grid refinement. This is done in the framework of inexact Newton methods in function space, where the discretization error of each Newton step is controlled by adaptive grid refinement in the innermost loop. This allows to perform most of the required Newton steps on coarse grids, such that the overall computational time is dominated by the last few steps. For this purpose we propose an a-posteriori error estimator for a problem suited norm.
    Keywords: ddc:510
    Language: English
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  • 36
    Publication Date: 2020-08-05
    Description: Ticket pricing in public transport usually takes a welfare or mnemonics maximization point of view. These approaches do not consider fairness in the sense that users of a shared infrastructure should pay for the costs that they generate. We propose an ansatz to determine fair ticket prices that combines concepts from cooperative game theory and integer programming. An application to pricing railway tickets for the intercity network of the Netherlands demonstrates that, in this sense, prices that are much fairer than standard ones can be computed in this way.
    Keywords: ddc:510
    Language: English
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  • 37
    Publication Date: 2014-02-26
    Description: We present a second order sharp interface finite volume method for the solution of the three-dimensional poisson equation with variable coefficients on Cartesian grids. In particular, we focus on interface problems with discontinuities in the coefficient, the source term, the solution, and the fluxes across the interface. The method uses standard piecewiese trilinear finite elements for normal cells and a double piecewise trilinear ansatz for the solution on cells intersected by the interface resulting always in a compact 27-point stencil. Singularities associated with vanishing partial volumes of intersected grid cells are removed by a two-term asymptotic approach. In contrast to the 2D method presented by two of the authors in [M.~Oevermann, R.~Klein: A Cartesian grid finite volume method for elliptic equations with variable coefficients and embedded interfaces, J.~Comp.~Phys.~219 (2006)] we use a minimization technique to determine the unknown coefficients of the double trilinear ansatz. This simplifies the treatment of the different cut-cell types and avoids additional special operations for degenerated interface topologies. The resulting set of linear equations has been solved with a BiCGSTAB solver preconditioned with an algebraic multigrid. In various testcases -- including large coefficient ratios and non-smooth interfaces -- the method achieves second order of accuracy in the L_inf and L_2 norm.
    Keywords: ddc:510
    Language: English
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  • 38
    Publication Date: 2020-08-05
    Description: Given a combinatorial optimization problem and a subset $N$ of natural numbers, we obtain a cardinality constrained version of this problem by permitting only those feasible solutions whose cardinalities are elements of $N$. In this paper we briefly touch on questions that addresses common grounds and differences of the complexity of a combinatorial optimization problem and its cardinality constrained version. Afterwards we focus on polytopes associated with cardinality constrained combinatorial optimization problems. Given an integer programming formulation for a combinatorial optimization problem, by essentially adding Grötschel's cardinality forcing inequalities, we obtain an integer programming formulation for its cardinality restricted version. Since the cardinality forcing inequalities in their original form are mostly not facet defining for the associated polyhedra, we discuss possibilities to strengthen them.
    Keywords: ddc:510
    Language: English
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  • 39
    Publication Date: 2020-08-05
    Description: This survey concerns optimization problems arising in the design of survivable communication networks. It turns out that such problems can be modeled in a natural way as non-compact linear programming formulations based on multicommodity flow network models. These non-compact formulations involve an exponential number of path flow variables, and therefore require column generation to be solved to optimality. We consider several path-based survivability mechanisms and present results, both known and new, on the complexity of the corresponding column generation problems (called the pricing problems). We discuss results for the case of the single link (or node) failures scenarios, and extend the considerations to multiple link failures. Further, we classify the design problems corresponding to different survivability mechanisms according to the structure of their pricing problem. Finally, we show that almost all encountered pricing problems are hard to solve for scenarios admitting multiple failures.
    Keywords: ddc:510
    Language: English
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  • 40
    Publication Date: 2021-02-19
    Description: We introduce an optimization model for the line planning problem in a public transportation system that aims at minimizing operational costs while ensuring a given level of quality of service in terms of available transport capacity. We discuss the computational complexity of the model for tree network topologies and line structures that arise in a real-world application at the Trolebus Integrated System in Quito. Computational results for this system are reported.
    Keywords: ddc:510
    Language: English
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  • 41
    Publication Date: 2021-02-19
    Description: Line planning is an important step in the strategic planning process of a public transportation system. In this paper, we discuss an optimization model for this problem in order to minimize operation costs while guaranteeing a certain level of quality of service, in terms of available transport capacity. We analyze the problem for path and tree network topologies as well as several categories of line operation that are important for the Quito Trolebus system. It turns out that, from a computational complexity worst case point of view, the problem is hard in all but the most simple variants. In practice, however, instances based on real data from the Trolebus System in Quito can be solved quite well, and significant optimization potentials can be demonstrated.
    Keywords: ddc:510
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  • 42
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 269 (1971), S. 48-56 
    ISSN: 1432-1912
    Keywords: Colloidal Ferrihexacyanoferrate(II) ; Potassium Hexacyanoferrate(II) ; Metabolism ; Toxicity ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intestinal absorption, distribution, and excretion of ferrihexacyanoferrate(II), labeled by59Fe at the Fe(III)- and Fe(II)-atoms, respectively, was studied in rats. Following i.v. injection, the compound is separated at ∼60% into Fe3+ and [Fe(CN)6]4−, the residual fraction being retained by the reticuloendothelial system. [Fe(CN)6]4− is excreted rapidly and virtually completely by the kidneys. With oral administration the disintegration amounts to ∼7%, and ∼2% of [Fe(CN)6]4− is absorbed from the gut. No evidence was obtained for decomposition of [Fe(CN)6]4−. No toxic side-effects were observed after chronic administration of ferrihexacyanoferrate(II).
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  • 43
    Electronic Resource
    Electronic Resource
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    Anatomy and embryology 135 (1971), S. 101-107 
    ISSN: 1432-0568
    Keywords: Rat ; Uterus ; Luminal epithelium ; Ultrastructure ; Implantation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of the rat uterine luminal epithelium has been examined during normal pregnancy, pseudopregnancy, lactation and lactation-pregnancy, all being conditions when a blastocyst is known to be able to implant. In all four groups of animals the epithelium passes through three characteristic and structurally similar states, namely a pre-attachment state, an attachment state and a postattachment state. The attachment state is characterized by a close contact between apposing luminal surfaces of the epithelium. It is concluded that implantation in an undamaged uterus claims a sequence of certain changes in the uterine luminal epithelium, and that the blastocyst attachment occurs within the early part of that period when the luminal epithelium is in the attachment state.
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  • 44
    ISSN: 1432-0568
    Keywords: Rat ; Ferro-dextran ; Blood brain barrier ; Circumventricular organs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Nach Vorbehandlung mit Myofer (Eisen III-Dextran) wurde die Aufnahme der Testsubstanz in den circumventriculären Organen von Rattengehirnen mit dem Licht-und Elektronenmikroskop untersucht. Die Ergebnisse zeigten, daß ein partieller Schrankeneffekt zwischen Gefäß und Gehirn auch in diesen Regionen besteht. Im allgemeinen ist der Schrankeneffekt die Folge hintereinandergeschalteter Barrieren, deren morphologisches Substrat 1. das Gefäßendothel und 2. die Gliagrenzschicht sind. Im Parenchym der verschiedenen Gehirnteile ist die Endothelzelle für diese gegebene Substanz undurchlässig. Dabei wird Myofer zwar in die Zelle aufgenommen, aber total zurückgehalten. In den circumventriculären Organen des Rattengehirns (Area postrema, Epiphyse, Subfornikalorgan, Organum vasculosum laminae terminalis, Neurohypophyse, Plexus chorioidei) ist die Endothelzelle durchlässig. Daher findet man Myoferpartikel im perivasculären Raum. Der. „Hemmeffekt” der zweiten Barriere ist abhängig 1. von der Konzentration des Myofers in dem perivasculären Raum und 2. von der Zeitdauer, während der die Gliagrenzschicht beeinflußt wird. Die perivasculären Gliafortsätze nehmen als einzige Zellelemente Myofer auf. Da der Anteil von Zellen mit Gliacharakter in den circumventriculären Organen wechselt, ist in den einzelen Regionen Myofer in unterschiedlicher Menge nachweisbar. Neuronale Elemente enthalten niemals Myofer.
    Notes: Summary After pretreatment of rats with Myofer (ferro-dextran complex) the uptake of this substance into circumventricular organs of the brain has been studied by means of light and electronmicroscopy. The results show that in these regions a partial barrier effect exists between blood and brain parenchyma. Generally the barrier effect is the result of impediments, which are connected in series. The morphological substratum of them is (1) the endothelium of the capillaries and (2) the limiting layer of the glial processes. In the parenchyma of the brain (cerebellum) the endothelial cell is sealed for this substance: the Myofer is taken up by the endothelium, but retained in the cells. In the circumventricular organs of the rat's brain (area postrema, epiphysis cerebri, subfornical organ, Organum vasculosum laminae terminalis, neurohypophysis, choroid plexus) the endothelial cells are leaky. Consequently one finds particles of Myofer inside the perivascular space. The inhibitory effect of the second barrier depends (1) on the concentration of Myofer in the perivascular space and (2) on the period, during which the limiting layer of the glial processes has been affected. The perivascular glial processes are the only cell elements which take up Myofer. Since the proportion of cells characterized as glial elements changes between the circumventricular organs, Myofer is detectable in different amounts within the various regions. Neuronal elements never contain Myofer.
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  • 45
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    Springer
    Anatomy and embryology 134 (1971), S. 311-327 
    ISSN: 1432-0568
    Keywords: Development ; Median eminence ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This paper reports details of the development of the external layer of the median eminence with special reference to the appearance of the nerve terminals, containing electron dense core and electron lucent vesicles, in the outermost layer of a palisade structure (2–3 μ thick). Observations were made on perinatal rats of the Sprague-Dawley strain (16, 18, 20 day fetuses and rats 5 hours, one 4, and 8 days after birth). The palisade structure of the outermost layer of the median eminence was first clearly detectable 5 hours after birth. Concomitantly, there was a marked increase in the number of nerve terminals in this layer. The nerve terminals containing electron dense core and electron lucent vesicles were seen in 18 day fetuses in the outermost layer of the median eminence. These nerve terminals increased in number during development, especially from the 20th day of fetal life to the 4th day after birth. The size range of the majority of the electron lucent vesicles did not change during development, but that of the core vesicles increased from 600–800 Å from the 18th to 20th day of fetal life. The initiation of neurohemal control of the adenohypophysial function by the hypothalamus is discussed.
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  • 46
    ISSN: 1432-0533
    Keywords: Co-Radiation ; Spinal Cord ; Rat ; Cell Proliferation ; p-Bromophenylacetylurea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Rats were irradiated with doses of 1 000–3 000 rads to the cervical spinal cord and subsequently given a paralytic dose of p-Bromophenylacetylurea. The nuclear populations in the degenerating dorsal columns were determined and it was found that a significant suppression of cell proliferation occurred after all three dose levels. The cell populations in the shielded parts of the tracts rostral to the irradiated zone were not affected.
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  • 47
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 19 (1971), S. 249-264 
    ISSN: 1432-0533
    Keywords: Brain Edema ; Stab Wound ; Neocortex ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The parietal cortex of rats was examined by light and electron microscopy 1–120 min after a standardized stab wound (250×450×1800μm, constant stab velocity). The changes in the tissue are already visible qualitatively after 1 min. After about 4 min the expansion of tissue changes stops. 4 zones may be separated. Surrounding the stab canal concentrically they are relatively sharply defined. Zone I. Stab canal, haemorrhagical or “debris zone”, primary traumatic destroyed zone. The tissue units are here completely destroyed. Zone II. “Squashed” or “indirectly but irreversibly damaged” zone. It is ca. 80μm wide and contains apart from a protein-rich extracellular fluid almost exclusively swollen cells and cell fragments. Zone III. Swelling brain or “intracellular peritraumatic edema”. It is ca. 150μm wide and contains mainly dark neurones and swollen astroglia. Zone IV. Transitional zone of variable width. Here only the perivascular and perineural processes are swollen without changed neurone structure. In all swollen astrocytes mitochondria are altered typically (denser matrix, dilated cristae). Discussed are: The short latency period, Zone IV, causes of astroglial swelling, origin of extracellular fluid as well as mechanisms which limit the spread of extracellular fluid into Zone II.
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  • 48
    Electronic Resource
    Electronic Resource
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    Experimental brain research 12 (1971), S. 435-446 
    ISSN: 1432-1106
    Keywords: Thalamic reticular nucleus ; Ascending reticular system ; Topo graphical arrangement ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A neuro-anatomical investigation into the thalamic reticular nucleus and its connections was made in the albino rat, using the method of retrograde degeneration and the Nauta-Gygax method. The results correspond to the description given by Scheibel and Scheibel and indicate connections of the neurons of the reticular which the principal thalamic nuclei and the rostral part of the intralaminar thalamic nuclei. A topographical arrangement of the efferent connections of the reticular nucleus is demonstrated. The projection of the reticular nucleus upon the thalamus duplicates the cortico-thalamic connections.
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  • 49
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    Naunyn-Schmiedeberg's archives of pharmacology 271 (1971), S. 211-233 
    ISSN: 1432-1912
    Keywords: Amphetamine ; Synthesis of Catecholamines ; Brain Catecholamines ; Release of Catecholamines ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Accumulation of labelled noradrenaline (NA) and dopamine (DA) and endogenous levels of NA and DA in brain and heart were measured after infusion of tyrosine-14C and dopa-3H in rats. After a single dose of 20 mg/kg i.p. of dl-amphetamine sulphate a 50–65% decrease in the NA accumulation in the brain and heart was observed. The accumulation of DA was not changed. In rats treated chronically with amphetamine sulphate, 16−32 mg/kg i.p. twice daily for 4 weeks, both the brain and heart NA and brain DA levels were depleted by 40–70% at 20–24 h after amphetamine withdrawal. The accumulation of labelled NA and DA in these animals was not different from that of saline treated controls. When amphetamine sulphate, 20 mg/kg i.p., was given to chronically amphetamine treated rats there was a 45–60% decrease in the accumulation of labelled NA; labelled DA remained unchanged. It is concluded that the decrease in NA accumulation under acute and chronic amphetamine intoxication is most likely due to a preferential release of newly synthesized NA.
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  • 50
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    Psychopharmacology 22 (1971), S. 144-150 
    ISSN: 1432-2072
    Keywords: Avoidance ; Chlorpromazine ; CS-US Interval ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Three groups of four rats learned to avoid electric shock (US) by turning a wheel in response to a buzzer stimulus (CS). The CS-US intervals for each group were 5, 10, and 20 sec, respectively. After each animal had learned the avoidance procedure and had achieved a stable level of performance, the effect of several doses of chlorpromazine on percent avoidance, on latency time from CS onset to termination by a response, and on response rate was determined as a function of CS-US interval length. No consistent relationship between increasing interval length and response rate was observed. Neither lengthening the CS-US interval nor the interaction of this lengthening with chlorpromazine dose was found to exert a statistically significant effect on percent avoidance. Furthermore, although a statistically significant increase in response latency was found to be associated with increasing CS-US interval length, the increases in latency noted were not of sufficient magnitude to corroborate the hypothesis that lengthening the CS-US interval contributes importantly to increased avoidance responding in animals tested with chlorpromazine. Further, the results of this study do not support induction of a locomotor deficit as the mechanism by which chlorpromazine suppresses the avoidance response.
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  • 51
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    Psychopharmacology 19 (1971), S. 95-104 
    ISSN: 1432-2072
    Keywords: Ethanol ; Tolerance ; Dependence ; Withdrawal Reaction ; Startle Threshold ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The thresholds for startle responses to electric shock were measured in adult male Wistar strain rats given ethanol daily in doses rising from 3 to 7 g/kg over a 30-day period, and in controls receiving equicaloric doses of sucrose. Tests made 23, 36, or 47 h after ethanol (i.e., during partial or complete ethanol withdrawal) gave threshold values significantly lower than those obtained with sucrose-treated controls. The difference became greater after longer ethanol treatment and larger doses. However, when threshold measurements were made under the acute influence of ethanol in the experimental group, the mean values were virtually equal to those of the sucrose controls. This normalization, by ethanol, of a disturbance produced by absence of ethanol in a chronically treated animal is indicative of physical dependence. Following termination of ethanol treatment there was a gradual return of startle thresholds almost to control values over a relatively short period, indicating that the changes underlying the hyperexcitability are readily reversible.
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  • 52
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    Psychopharmacology 21 (1971), S. 212-228 
    ISSN: 1432-2072
    Keywords: Amphetamine ; Apomorphine ; Stereotypy ; Behaviour ; Rat ; Mouse ; Neuroleptics ; Thymoleptics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The behaviour of mice after various doses of amphetamine or apomorphine which induce stereotypies is described in details. The induced stereotyped behaviour in mice appears more differentiated than that in rats. The amphetamine-syndrome in rats consists of an excitement phase followed by the stereotypy, whereas apomorphine elicits stereotyped behaviour directly after administration. Amphetamine-induced stereotyped behaviour is different from the apomorphine-induced stereotypy in several respects. Neuroleptics inhibit the amphetamine (12.5 mg/kg s.c.) and apomorphine-(10 mg/kg s.c.) syndrome, while thymoleptics potentiate subeffective doses of amphetamine (5 mg/kg s.c.) and apomorphine (2 mg/kg s.c.). This is demonstrated with some neuroleptics of the phenothiazine-type, haloperidol, reserpine, and a group of thymoleptics. The method opens the possibility of differentiating within several groups of neuroleptics and within several groups of thymoleptics.
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  • 53
    ISSN: 1432-2072
    Keywords: Acquisition ; CAR ; Tetrahydrocannabinols ; Transfer ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats trained in conditioned avoidance responding (CAR) after injections of either 7.5 mg/kg Δ 9-THC (tetrahydrocannabinol) or 15 mg/kg Δ 8-THC, showed no transfer when tested in the non-drugged state. Furthermore, these doses of the isomeric tetrahydrocannabinols exerted a disruptive effect on previously established CAR in rats, trained under normal conditions. Only the Δ 9-THC-group showed an impairment of acquisition which was statistically significant compared to the control group.
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  • 54
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    Psychopharmacology 21 (1971), S. 147-156 
    ISSN: 1432-2072
    Keywords: Scopolamine ; Pilocarpine ; Lashley Jumping Stand ; Fixated Behavior ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A group of male albino rats were subjected to the Maier paradigm (insoluble problem followed by a soluble problem) using the Lashley jumping stand. Forty-two animals which failed the soluble problem by adopting a position stereotype were then randomly assigned to eight drug groups in a 2×2 design. Animals were guided to the correct window on odd days but received no guidance on even days. Animals received either pilocarpine nitrate (5.0 mg/kg) or scopolamine hydrobromide (1.0 mg/kg) in one of three different sequences. These sequences included drug on both odd and even days (drug-drug), only on the odd day (drug-no drug), or only on the even day (no drug-drug). One other drug group received scopolamine methylbromide (1.0 mg/kg) in a drug-no drug sequence, while the control group received saline on both days. Results indicated that animals receiving pilocarpine in the drug-drug and no drug-drug sequence solved significantly faster than the controls, while all the drugno drug groups showed significantly poorer solution rates. It was concluded that pilocarpine may enable animals to inhibit punished behavior patterns and thus hasten the extinction of fixated responses, but that due to the inconclusive scopolamine data this pilocarpine effect may not be due to its cholinomimetic properties.
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  • 55
    ISSN: 1432-2072
    Keywords: NE ; Intraventricular ; Cholinergic Function ; Eating Behaviour ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of centrally administered norepinephrine (NE) into the lateral ventricle on choline acetylase activity (ChAc), endogenous levels of NE, dopamine (DA) and serotonin (5HT) was studied in different regions of the rat brain. In normal rats, the highest activity of choline acetylase was found in the cerebral cortex, followed by the brain stem, the diencephalon, the hypothalamus and least in the cerebellum. Chronic administration of NE significantly increased the choline acetylase activity in all regions studied, whereas both the acute and the in vitro studies showed no significant change except in the brain stem. Serotonin level was increased in the cerebellum, but decreased in the diencephalon and the brain stem. There was no significant alteration in the level of NE in all areas studied except in the hypothalamus where there was an increase in the mean concentration. Tissue level of DA showed a significant increase in the cerebral cortex and the hypothalamus. Behaviourally, there was a significant increase in food intake on the first day of treatment with no significant change in water intake. The data suggests that NE may be involved in the regulation of acetylcholine synthesis. The significance of interaction between different monoamines and acetylcholine may be important in the study of drug tolerance phenomena.
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  • 56
    ISSN: 1432-1106
    Keywords: GABA-Regional distribution ; Rabbit ; Rat ; Guinea pig ; Baboon ; CNS ; Substantia nigra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The regional distribution of GABA in the CNS of rabbit (17 regions), rat (14 regions), guinea pig (12 regions) and baboon (11 regions) was determined by sensitive enzymatic and fluorometric assay. In all species studied a high concentration of GABA was found in substantia nigra (8.5–10.1 mmoles/kg) and pallidum (6.5–8.2 mmoles/kg). Fairly high amounts were found in hypothalamus, superior and inferior colliculi, nucleus oculomotorius and dentate nucleus. The GABA concentration in spinal cord (white matter) had the lowest value.
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  • 57
    ISSN: 1432-2013
    Keywords: NaKATPase ; Intracellular Localisation ; Proximal Tubule ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary With refinements of quantitative histochemistry, i.e. oilwell technique, enzymaticP ianalysis and NADP/NADPH cycling an enzymatic polarization of the tubular epithelial cell from the rat nephron to NaKATPase can be established. NaKATPase activity is limited to the basal area of the epithelial cell. Brush border fragments lack NaKATPase activity.
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  • 58
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    Psychopharmacology 20 (1971), S. 389-394 
    ISSN: 1432-2072
    Keywords: Aggressive Behaviour ; Apomorphine ; Isolation ; Psycho pharmacology ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The apomorphine-induced aggression response of isolated rats was examined. The development of aggressive behaviour in adult rats was enhanced after isolation in cages with wire-netting and especially in cages isolated in opacified Makrolon boxes compared with aggregated rats. Young rats kept isolated for 2 months immediately after weaning showed an enhancement only if isolated in wire-netting cages. Rats kept in groups for one month after their isolation still showed an enhancement of aggression, although it was somewhat reduced.
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  • 59
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    Psychopharmacology 20 (1971), S. 348-354 
    ISSN: 1432-2072
    Keywords: Phentolamine ; Noradrenaline ; Amphetamine ; Rat ; Locomotor Activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Phentolamine injected intraventricularly in unanaesthetized rats decreased their locomotor activity and antagonized the excitatory effect of intraventricularly injected noradrenaline, or amphetamine injected s.c. Phentolamine did not influence the level of noradrenaline and 5-hydroxytryptamine in the rat brain. The mechanism of observed action of phentolamine is discussed.
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  • 60
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    Psychopharmacology 21 (1971), S. 165-173 
    ISSN: 1432-2072
    Keywords: Anorexic Effect ; Fenfluramine ; Activity Analysis ; Time Sampling Technique ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Three experiments are reported investigating the effects of acute administration of fenfluramine over 3 doses on activity, eating and drinking behaviour. A time sampling procedure of activity analysis was used, employing six behaviour categories. Fenfluramine produced a dose related decrease in rearing behaviours, with some evidence of an increase in walking categories at the lower dose levels. Eating and drinking behaviours showed clear dose related decreases. Sniffing categories showed a clear dose related increase. Attention is drawn to some of the difficulties of interpretation and assessment of anorexic effect.
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  • 61
    ISSN: 1432-2072
    Keywords: Alperenolol ; Amphetamine ; Brain Amines ; Behaviour ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The influence of alprenolol and amphetamine alone or combined on the content of noradrenaline, dopamine and 5-hydroxytryptamine in seven discrete areas of the brain and on rat behaviour was studied. Animals were treated with drugs for 6 months. Alprenolol caused mainly a decrease of the estimated endogenous amines in different brain areas. Amphetamine caused a decrease of all three amines in some parts of the brain, and reversed some of the changes caused by alprenolol. Alprenolol had no effect on the locomotor activity of rats, but increased the activity of rats treated with amphetamine after the first week of treatment, and antagonized the excitatory effect caused by amphetamine during the following weeks of the experiment.
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  • 62
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    Naunyn-Schmiedeberg's archives of pharmacology 270 (1971), S. 22-40 
    ISSN: 1432-1912
    Keywords: Intestinal Blood Flow ; Intestinal Absorption ; Polyalcohols ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Jejunal loops of anaesthetized rats were perfused with14C-labelled polyalcohols in buffered saline solutions at pH 7. The blood flow, the disappearance rate (from the intestinal lumen), and the appearance rate (in the intestinal venous blood) were determined simultaneously. 2. A decrease of the blood flow from about 1.8 to 0.25 ml min−1g−1 wet tissue diminished the disappearance and appearance rate of the substances and their possible metabolites. An increase of the blood flow caused the reversed results. The two transfer rates and their dependence on blood flow decreased with increasing molecular weight of the polyalcohols. 3. The appearance rate of glycerol showed a different dependence on blood flow in experiments with increasing and decreasing blood flow. This phenomenon can be explained by a decreasing permeability of the epithelium for glycerol with time. The cause for it is unknown. 4. By means of a three-compartment-model blood flow independent permeability coefficients of the polyalcohols are derived for the intestinal epithelium. They are consistent with an equivalent pore radius of 3.9±0.1 Å.
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  • 63
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    Cell & tissue research 116 (1971), S. 151-156 
    ISSN: 1432-0878
    Keywords: Adrenal cortex ; Innervation ; Receptors ; Rat ; Pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The innervation of the adrenal cortex of the rat and the pig is investigated with the electron microscope. Nerve fibers containing synaptic and two types of dense-cored vesicles come into contact with endocrine cells. There are no specialized pre- and postsynaptic membranes. The synaptic cleft is about 200 Å wide. Generally the basement membrane between nerve and cell is absent. These observations are discussed on the base of more recent experimental findings. Small fibers having an average diameter of about 0.2 to 0.5 μ and containing only tubules and filaments are considered to represent parts of an afferent nervous system.
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  • 64
    ISSN: 1432-0878
    Keywords: Adrenergic neurons ; “Short” and “long” systems ; Pre- and postnatal development ; Peripheral organs ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The adrenergic innervation in the submaxillary gland, heart, kidney, small intestine, and accessory male genital organs and the development of the adrenal chromaffin cells and the sympathetic ganglia were studied in the rat from 15 days post coitum to 16 days post partum using the fluorescence histochemical method of Falck and Hillarp. The postnatal development of the noradrenaline concentrations in the heart and vas deferens was followed by fluorometric determinations. At about 15 days post coitum, the anlagen of the sympathetic chains were well visible in the form of two dorsal segmented columns of small branching sympathicoblasts exhibiting an intense catecholamine fluorescence. In the midline, ventrally to these two anlagen, another column of sympathicoblasts developed; this seemed to give rise to the prevertebral ganglia and to the short adrenergic neurons supplying the internal genital organs. At the level of the adrenal anlagen, small intensely fluorescent chromaffin cells were collected in two bilateral groups which became enclosed by adreno-cortical cells. This enclosure was, however, not complete even at two weeks post partum. Bundles of growing sympathetic nerves were visible in the periphery of the various organs studied at 19–21 days post coitum. A terminal innervation of the organs suggestive of a functional transmitter mechanism did not start to establish until at or immediately after birth. The final pattern of innervation was usually reached at about one week post partum, and the following development proceeded largely in the form of a quantitative increase in the number of nerves participating in the innervation apparatus. The adult level of noradrenaline in the heart and vas deferens was reached three to five weeks after birth. The small intestine was an exception in that the final pattern of innervation in the wall was attained immediately after birth. There was no overt difference in the rate of development of the terminal sympathetic innervation in organs supplied by short adrenergic neurons (accessory male genital organs) compared to the innervation of the submaxillary gland, heart and kidney, which receive classical long adrenergic neurons.
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  • 65
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    Cell & tissue research 119 (1971), S. 58-67 
    ISSN: 1432-0878
    Keywords: Ovary ; Rat ; Fowl ; Granulosa cells ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The granulosa cells of the ovarian follicle of the rat and the domestic fowl have been studied with the light and electron microscope. The nuclei of the granulosa cells were irregular with indentations and large in proportion to the cytoplasm of the cell. The mitochondria had a dense, dark matrix with only few cristac. The Golgi apparatus was moderately developed, located towards the oocyte in a juxtanuclear position. The endoplasmic reticulum was rather sparse. Lipid droplets were only occasionally encountered. Microtubules were regularly observed. The functions of the granulosa cells are discussed. Compared with the steroid-producing cells of the theca interna of the same follicles, the granulosa cells primarily are the nursing cells for the growing oocyte and mainly have the characteristics of protein forming cells.
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  • 66
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    Cell & tissue research 122 (1971), S. 283-300 
    ISSN: 1432-0878
    Keywords: Paraventricular nucleus ; Rat ; Synthesis of hormones ; Acid phosphatase ; Osmium impregnation ; Neurosecretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural features of the paraventricular neurones of the non-treated rat are presented comparing them with those of the supraoptic neurones. No striking differences are seen between the general electron microscopic characteristics of the paraventricular and supraoptic neurones. The importance of adequate fixation to obtain good preservation of the neurones is emphasized, since inadequate fixation can cause e.g. artefactual appearance of “dark neurones”. The previously presented classification of the neurosecretory neurones into two categories (e.g. “light and dark neurones”) on the basis of the number of ribosomes is not considered justifiable, since their number can vary to a very great extent even within a single cell. The synthesis of neurosecretory products in the paraventricular neurones obviously follows the general mode of the synthesis of secretory proteins: ribosomes—RER—Golgi complex—secretory vesicles. On the basis of the localization of heavy metal deposits after osmium impregnation and demonstration of acid phosphatase the Golgi complex of the paraventricular neurones is found to be polarized. The direction of the polarity is discussed. The substructures of the dense cores of the neurosecretory granules and of the contents of the lysosomal dense bodies are nearly identical. Therefore it is considered impossible to determine positively the nature of the dark condensed material within the Golgi complex. The characteristics of the immature neurosecretory granules and the possibility of releasing neurosecretory products into the cytoplasm already within the perikarya are speculated.
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  • 67
    ISSN: 1432-0878
    Keywords: Smooth muscle ; Two-filament system ; Small intestine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structure of glycerinated smooth muscle from small intestine of adult rat was investigated by electron microscopy. In the central parts of the tissue blocks a two-filament system was found, consisting of parallel thick and thin filaments with regularly spaced interconnections, closely resembling that of striated muscle. In the peripheral parts of the blocks only thin filaments were found. The thin filaments were identified as actin by the formation of arrowhead complexes after incubation with heavy meromyosin.
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  • 68
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    Cell & tissue research 121 (1971), S. 531-547 
    ISSN: 1432-0878
    Keywords: Helical polyribosomes ; Skeletal muscle ; Polysomes ; Levator ani ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The localization and configurations of ribosomes in mature white skeletal muscle fibers of the rat were investigated. Differential visualization of ribosomes and glycogen granules was obtained by fixation with glutaraldehyde only and staining of the sections with uranyl acetate. Ribosomes are then electron dense and glycogen granules electron transparent. Their identity was ascertained by selective extractions of ribonucleic acid and polysaccharide. The vast majority of the ribosomes is not membrane-bound. They are located intermyofibrillarly (predominantly at the level of the I-bands), beneath the sarcolemma, and in the paranuclear cones of sarcoplasm. Occasionally short stretches of granular reticulum occur, often as characteristic double walled vesicles with ribosomes on the inner membrane only. Three main types of polysomal configurations are observed: rosettes of 4 to 6 ribosomes, helical arrays, and whorls of up to about 25 probably membrane-bound ribosomes. The average number of ribosomes in the extended helical configurations is estimated to be about 60. It is argued that these helices represent the polysomes instrumental in the synthesis of the large subunits of myosin. It is emphasized that helical polyribosomes are by no means typical of striated muscle, but probably represent a common configuration of large free polysomes.
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  • 69
    ISSN: 1432-0878
    Keywords: Ependyma ; Thiobarbiturate narcosis ; Cell nucleus shrinkage ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Im Ependym des Hypothalamus wurde das Verhalten der Zellkern-Membran nach ausgedehnter intraperitonealer Thiobarbiturat-Narkose untersucht. Die Kernmembran ist gefaltet, der Zellkern zeigt Zeichen von Schrumpfung. Diese Veränderung ist reversibel und wird nicht von der mit der Narkose verbundenen Entwässerung verursacht. Elektronenmikroskopische Untersuchungen lassen einen normalen Stoffwechsel vermuten, Zeichen von Pyknose fehlen.
    Notes: Summary Effects on the nuclear membrane were investigated in hypothalamic ependymal cells of the rat during prolonged intraperitoneal thiobarbiturate narcosis. The nuclear membrane of the nucleus was folded and the nucleus showed signs of shrinkage. These alterations were reversible and did not depend on the dehydration which developed during the narcosis. Ultrastructural signs and the absence of pyknosis suggested that metabolism during nuclear shrinkage may be normal.
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  • 70
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    Cell & tissue research 113 (1971), S. 157-173 
    ISSN: 1432-0878
    Keywords: Prostate ; Development ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The postnatal development of the rat prostate has been studied with the electron microscope. Major developmental changes begin during the second week after birth and involve organelles associated with the formation of secretions. The amount of granular endoplasmic reticulum and the size of the Golgi complex increase greatly. Large vacuoles that probably contain secretory material are formed, and the lumen of the prostatic acini appears to contain secreted material. Large lysosomes with polymorphic interiors are present as early as 10 days after birth, and they become numerous by the end of the third week. Differences in fine structure between the different lobes of the prostate are detectable in 10–14 day old rats. The subsequent differentiation of the granular endoplasmic reticulum into the forms characteristic of the different prostatic lobes is described. The initial changes in the prostate occur in advance of sexual maturity of the animal, and the adult appearance of the gland is attained by 4–5 weeks after birth.
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  • 71
    ISSN: 1432-0878
    Keywords: Neurosecretory cells ; Rat ; Cytoplasmic bodies resembling nucleoli ; Paranucleolar and coiled bodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A distinctive cytoplasmic inclusion, termed nucleolus-resembling body, was identified in the neurons, but not in the glial cells, of the medial vascular prechiasmatic gland, the preoptic recess and the anterior part of the suprachiasmatic area in the rat. This ultrastructure which lacks a limiting membrane is made of an entanglement of tightly packed filaments, 60–70 Å in diameter. Each filament consists of smaller units, 15–20 Å thick. Usually, only one such ultrastructure is present in a cell, but at time two were identified. It is present in most neurosecretory cells. It is surrounded by polyribosomes in the perikaryon of the nerve cells. Furthermore, it is linked to peripherally located ribosomes by means of filaments, 70 Å in diameter. A possible function in protein synthesis of structural components, such as neurofilaments, is hypothesized. Two distinctive fibrillar areas were identified in the nucleolus according to the tightness with which fibrils were packed together. Their significance is discussed. Nucleolar extrusions were never observed in our studies. Paranucleolar and coiled bodies were identified in the nuclear sap. The mechanism of formation and the significance of these bodies are discussed.
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  • 72
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    Cell & tissue research 115 (1971), S. 30-45 
    ISSN: 1432-0878
    Keywords: Adrenal Cortex ; ACTH ; Autoradiography ; Stereology ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The changes occurring in rat adrenocortical cells (zona fasciculata) during an 8 day period of treatment with ACTH, were investigated by morphometric and autoradiographic methods. The most important ultrastructural change consists in a conspicuous increase in the smooth endoplasmic reticulum, that accounts for about 50% of the total increase of cellular volume. Also the mitochondrial fraction shows a significant increase, which is found to be due both to the increment in the number of mitochondria per cell and to the increase in the mean volume of organelles themselves. The quantitative autoradiographic data, indicating an increment in the incorporation of 3H-orotate and 3H-leucine into adrenocortical cells of the treated animals, allow us to conclude that the ACTH-induced ultrastructural changes are the morphological expression of a stimulation of the cellular protein synthesis. Since mitochondria are largely autonomous in the synthesis of their enzymes and structural proteins, it is possible to hypothesize that ACTH also intervenes in the regulation of the mitochondrial protein synthesis.
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  • 73
    ISSN: 1432-0878
    Keywords: Adenohypophysis ; Pars intermedia ; Corticotrophic cells ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Nos observations démontrent l'existence de deux types de cellules glandulaires dans la pars intermedia de l'hypophyse du rat: des cellules propres, à M.S.H., dont les grains de sécrétion sont détruits par la fixation osmiée et relativement bien conservés par la fixation au glutaraldéhyde; des cellules à petits grains denses, osmio-résistants, qui s'apparentent morphologiquement aux éléments corticotropes de l'antéhypophyse. L'existence bien connue d'A.C.T.H. ou, plus précisément, d'un facteur ≪A.C.T.H.-like≫ dans le lobe neuro-intermédiaire nous fait considérer comme très vraisemblable la nature corticotrope de ce deuxième type cellulaire de la pars intermedia.
    Notes: Summary Two types of glandular cells have been shown to occur in the intermediate lobe of the rat hypophysis: 1) M.S.H. producing cells whose secretory granules are destroyed by osmium fixation and relatively well preserved by glutaraldehyde fixation, 2) cells with small dense osmium resistant granules being morphologically similar to the corticotrophic cells of the anterior lobe. The well known occurrence of A.C.T.H. or, more precisely, of an “A.C.T.H.-like” factor in the neuro-intermediate lobe makes the corticotrophic nature of this second cell type very likely.
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    Cell & tissue research 117 (1971), S. 191-211 
    ISSN: 1432-0878
    Keywords: Sensory neurons ; Rat ; Nerve section ; Neurofilaments ; Neurofibrils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Sensory neurons were examined in spinal ganglia of the rat 1 to 55 days after section of the plexus brachialis nerves. Only “light” neurons of the type A were investigated. Maximal reaction to axotomy was found 7 to 14 days after the operation. The majority of the axotomized perikarya developed central chromatolysis. In such neurons, Nissl bodies virtually disappeared from the central area of the neuron and formed a more or less continuous zone at the cell circumference. The cytocentrum became filled with large numbers of mitochondria, dense bodies and other organelles. Neurofilaments and microtubules were disarranged and ran at random among the accumulated particles. Microtubules were often more prominent in chromatolytic areas than neurofilaments. Both these organelles were rare in the peripheral areas filled with massed Nissl substance. Part of the neurons that did not show typical chromatolysis contained increased numbers of neurofilaments among Nissl bodies dispersed throughout the cytoplasm. Neurofilaments were roughly arrayed in bundles up to several microns wide; they were linked by cross-bridges and separated by distances of about 500 Å. Microtubules were rarely found in the filamentous areas. However, they were numerous in the axon hillock and in the initial segment where they formed fascicles similar to those described in normal neurons of other types. During the period from 14 to 55 days after axotomy, many perikarya recovering from chromatolysis contained enlarged bundles of neurofilaments with occasional microtubules among the restored Nissl bodies. Mean diameters of sensory neurons, measured 7 to 55 days after axotomy, in no instance exceeded those of contralateral control neurons. It thus appears that sensory perikarya do not increase in size either during the chromatolytic process or during the period of recovery.
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    Cell & tissue research 116 (1971), S. 136-150 
    ISSN: 1432-0878
    Keywords: Adrenal cortex ; Rat ; Sex difference ; ACTH ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Nebennierenrinde von 178 Sprague-Dawley-Ratten wurde elektronenmikroskopisch von der 1.–12. Lebenswoche unter Normalbedingungen sowie nach s.c. Injektion von 3 IE ACTH/100 g Körpergewicht innerhalb von 2 min — 24 Std untersucht. Ab der 5. Lebenswoche unterscheiden sich die Nebennieren von Weibchen im Bereich der äußeren Zona fasciculata durch Kernvergrößerung, größere Mitochondrien und kleindisperse Liposomen von denen der Männchen. Zyklusbedingte Schwankungen in der Ultrastruktur der weiblichen Nebennierenrinde bestehen nicht. Nach ACTH-Applikation nähert sich das Nebennierenbild des Männchen innerhalb von 30 min dem des unbehandelten Weibchens. Außerdem kommt es bei beiden Geschlechtern durch ACTH zu einer Dispersion und Reduktion der Liposomen, Vergrößerung des Golgiapparates und der Zellkerne, Ausweitung des endoplasmatischen Retikulums und Vermehrung der Mikrovilli. Der Geschlechtsdimorphismus wird funktionell erklärt.
    Notes: Summary 178 Sprague-Dawley-rats were studied by electron microscopy from the 1st to the 12th week of life under normal conditions and after s. c. injection of 3 I. U. ACTH/100 gbodyweight from 2 min to 24 hours. Beginning with the 5th week of life females differ from males by small dispersed liposomes and enlarged nuclei and mitochondria in the outer z. fasciculata. There is no change in the ultrastructure of the female adrenal cortex depending on the sexual cycle. After application of ACTH the adrenal cortex of males assimilates to the untreated females within 30 min. After ACTH-application both sexes show dispersion and reduction of liposomes, dilation of endoplasmatic reticulum, increasement of microvilli and enlargement of the Golgi apparatus. The sex-dimorphism is interpreted by functional differences.
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    Cell & tissue research 119 (1971), S. 378-383 
    ISSN: 1432-0878
    Keywords: Seminal vesicles ; Rat ; Epithelium ; Proliferation activity ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung An 12 männlichen weißen Wistarratten unterschiedlichen Alters wurde autoradiographisch die Proliferation des Samenblasenepithels zur Zeit der Pubertät geprüft. Die Tiere waren 21, 29, 40, 50, 60 und 180 Tage alt und erhielten 1 Std vor der Tötung durch Dekapitation 2,5 μC 3H-Thymidin/g Körpergewicht i. p. appliziert. Ausgewertet wurden Autoradiogramme nach einer Expositionszeit von 18 Tagen; bestimmt wurde der Prozentsatz der markierten Zellkerne (3H-Index). Im Gegensatz zu dem bekannten exponentiellen Abfall des 3H-Indexes bei nicht-hormonabhängigen Leberepithelien jugendlicher Ratten kommt es beim Epithel der Samenblasen um den 40. Lebenstag zu einem erneuten, starken Proliferationsschub. Diese starke Wachstumszunahme ist wahrscheinlich der proliferationskinetische Ausdruck der nach Steinberger (1970) zur gleichen Zeit stattfindenden hormonellen Umschaltung in den Testes. Anschließend geht das Vermehrungswachstum des jugendlichen Tieres, durch das die Zellzahl erhöht wird, in das Erhaltungswachstum über; der 3H-Index des Samenblasenepithels erreicht den Wert des erwachsenen Tieres.
    Notes: Summary In 12 male white rats (Wistar) the proliferative activity of the epithelial cells in the seminal vesicles was studied by autoradiography. The animals were 21, 29, 40, 50, 60 and 180 days old. Each animal was given 2.5 μC/g 3H-thymidine and was killed 1 hour thereafter. We analysed the autoradiograms recording the percentage of labelled nuclei (3H-index). While the 3H-index of the non hormone-dependent epithelial cells in the liver of young rats declines continously with growing age (Stocker et al., 1964), the epithelial cells in the seminal vesicles of 40 days old rats show a remarkable rise in their proliferative activity. It is quite possible that this new peak in the proliferation is the morphological result of a preceeding switch in hormonal production of the testes as reported by Steinberger (1970). Thereafter the growth proliferation of the young rats declines into the steady state of the grown up.
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    Cell & tissue research 119 (1971), S. 334-354 
    ISSN: 1432-0878
    Keywords: Fat absorption ; Small intestine ; Rat ; Micropinocytosis ; Circadian rhythm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die vorliegende Untersuchung will klären, welche Rolle die Mikropinocytose bei der Fettresorption spielt und ob die Fettresorption tagesrhythmische Schwankungen aufweist. Zu diesem Zweck wurde Fett zu verschiedenen Tages- und Nachtzeiten in abgebundene Jejunumabschnitte von Ratten injiziert, das Darmgewebe in verschiedenen Abständen licht- und elektronenmikroskopisch untersucht und die Zahl der mikropinocytotischen Invaginationen der Enterocyten bestimmt. Folgende Resultate wurden erzielt: Die Häufigkeit der Mikropinocytose (mikropinocytotische Invaginationen/100 Mikrovilli) beträgt bei Hungertieren 4,78, bei Normaltieren 5,06, 1 min nach Gabe von Mazolachymus 3,55, 1/16 m NaCl-Lösung 4,37, Butterschmalz 5,50, Rindertalg 7,16, Schweineschmalz 7,66 und Mazola 9,25; 2 1/2 min nach Mazolagabe 8,23, nach 5 min 7,67, nach 10 min 6,76. Zwischen 10 und 15 min wird der Ausgangswert erreicht. Aufgrund statistischer Auswertung der Befunde wird geschlossen, daß Fett vor allem in den Frühstadien der Fettresorption durch Mikropinocytose aufgenommen werden könnte. Ferner zeigt sich, daß die Mikropinocytosehäufigkeit entscheidend von der chemischen Zusammensetzung und dem physikalischchemischen Zustand der verabreichten Fette beeinflußt werden dürfte. — Lichtmikroskopisch wurde nachgewiesen, daß die Fettresorption charakteristische, tagesrhythmische Schwankungen aufweist. Um 2.00 Uhr ist sie am stärksten, um 14.00 Uhr am geringsten. Es wird diskutiert, worauf die tagesrhythmischen Unterschiede zurückzuführen sind.
    Notes: Summary The present study attempts to elucidate (a) to what extent micropinocytosis is involved in the process of fat absorption and (b) whether fat absorption shows a circadian rhythm. For this purpose rats were given 0.1 to 0.15 ml of fat directly into the upper jejunum at various times of the day and night. 20 sec to 20 min after administration of fat small pieces of the jejunum were rapidly dissected out, the tissue examined by means of light- and electron microscopy, and the number of micropinocytotic pits occurring in the enterocytes during fat absorption was determined. The following results were obtained: The frequency of micropinocytosis (micropinocytotic pits/100 microvilli) is as follows: in starved rats 4.78, in normal rats 5.06, 1 min after administration of corn oil chyme 3.55, 1/16 m NaCl-solution 4.37, clarified butter 5.50, ox tallow 7.16, lard 7.66, corn oil 9.25; 2 1/2 min after administration of corn oil 8.23, after 5 min 7.67, and after 10 min 6.76. Between 10 and 15 min the number of micropinocytotic pits reverses to normal. From statistical analysis of the results it is concluded that micropinocytosis can play a significant role in the early stages of fat absorption. The experiments show in addition that micropinocytosis is greatly influenced by the chemical composition and the physico-chemical state of the administered fat.—Light microscopic studies indicate that fat absorption varies considerably during the 24 hr period. The highest absorption was found at 2 a.m., the lowest at 2 p.m.
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  • 78
    ISSN: 1432-0878
    Keywords: Substantia nigra ; Rat ; Incorparation of 3H-Dopamine, 3H-Serotonin and 3H-Norepinephrine ; Axo-dendritic Synapses ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In autoradiographies of substantia nigra in rat, it has been observed that after intraventricular injections of 3H-dopamine and 3H-norepinephrine respectively the silvergrains are accumulated in nigra neurons and their dendritic branches. The incorporation was more pronounced in the case of 3H-norepinephrine than 3H-dopamine. This seems to indicate that exogenous norepinephrine may have stronger affinity to nigra neurons and their dendrites than exogenous dopamine. In addition, some 3H-dopamine and 3H-norepinephrine labelled nerve terminals were observed in axo-dendritic synapses. In contrast to these data, 3H-5HTP and 3H-5HT administration showed almost all silver grains accumulated in the neuropil when observed in light microscopic autoradiography. Electron micrographs further reveal that the incorporation of 3H-5HTP and 3H-5HT was mostly within axo-dendritic boutons with more frequent dense core vesicles. These data again strongly suggest that substantia nigra receives a large number of serotoninergic fibres forming axo-dendritic synapses which may play an important role in modulation of substantia nigra function.
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  • 79
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    Cell & tissue research 114 (1971), S. 271-280 
    ISSN: 1432-0878
    Keywords: Thymus ; Rat ; Involution ; Reticulum-Cells ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung 1. Entodermale Thymus-Retikulumzellen neugeborener Wistar-Ratten enthalten häufig helle Vesikel mit enger räumlicher Beziehung zum Golgi-Apparat. Bei 13 Monate alten Ratten fehlen diese Vesikel. 2. Die Tatsache, daß die Häufigkeit heller Vesikel mit fortschreitendem Lebensalter abnimmt, findet ihre Parallele in der von anderer Seite getroffenen Feststellung, daß die Bildung eines humoralen Faktors im Thymus im Laufe der Zeit eingeschränkt wird. 3. Diese Koinzidenz läßt an die Möglichkeit denken, die hellen Vesikel könnten ein morphologisches Äquivalent der Bildung eines Thymuswirkstoffes sein. 4. In entodermalen Thymus-Retikulumzellen 13 Monate alter Ratten finden sich große Vakuolen mit granulärem Inhalt. Ihre Bildung beginnt schon vor der Thymusinvolution. Sie entstehen wahrscheinlich durch Phagozytose oder Aufnahme zelleigenen Materials, das nicht weiter abbaufähig ist. 5. Da diese Einschlüsse mit fortgesetzem Alter an Zahl und Größe zunehmen, scheinen sie als Ausdruck einer Beeinträchtigung der Stoffwechselvorgänge im Zytoplasma ein erstes morphologisch faßbares Symptom der frühzeitigen physiologischen Involution des Thymus zu sein.
    Notes: Summary 1. Entodermal reticulum cells of new born Wistar rats frequently contain clear vesicles with close connection to the Golgifield. These vesicles do not occur in reticulum cells of 13 months old rats. 2. The frequency of these clear vesicles decreases with advancing age obviously in the same way as the production of a humoral thymic factor reported by several investigators. 3. This observation agrees with the hypothesis that the clear vesicles are the morphological equivalent of the production of a humoral thymus factor. 4. Entodermal reticulum cells of 13 months old Wistar rats contain large vacuoles filled with electron dense, granulated materials. The formation of these vacuoles starts already before the beginning of the thymus involution. Possibly they are produced by phagocytosis or necrobiosis and contain deposits of material that cannot undergo further degradation. 5. The increase of these vacuoles in number and size with advancing age may be considered as equivalent of the deterioration of metabolism responsible for early involution of the thymus.
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  • 80
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    Cell & tissue research 116 (1971), S. 61-69 
    ISSN: 1432-0878
    Keywords: Paraventricular nucleus ; Rat ; Types of neurons ; TRF-synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural aspects of the paraventricular nucleus and its neuropil are described in the normal rat. Two types of neurons can be distinguished morphologically. The first type contains numerous dense-core vesicles (mean diameter: 140 nm). The cisternae of the endoplasmic reticulum are arranged parallely at the periphery of the cell body. The second type of neuron contains a few dense-core vesicles (mean diameter: 75 nm) and the endoplasmic reticulum is randomly distributed in the cytoplasm. In the neuropil, two types of dense-core vesicles are observed in separated axons. The histogram of the distribution of their mean diameter clearly indicates a double population of vesicles. The signification of the second type of neuron in the paraventricular nucleus is discussed and its possible relation to TRF synthesis is evoked.
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  • 81
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    Cell & tissue research 116 (1971), S. 119-135 
    ISSN: 1432-0878
    Keywords: Adrenal cortex ; Rat ; Sex difference ; Light microscopy ; Histometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung An 260 männlichen und weiblichen Sprague-Daweley-Ratten vom 0. Lebenstag bis zur 12. Lebenswoche wird die geschlechtsdifferente Entwicklung der Nebennierenrinde histologisch und histometrisch verfolgt. Von der 4. Lebenswoche an ist die weibliche Fasciculatazelle durch ein helles, fein-granuläres Cytoplasma ohne distinkt abgrenzbare Fettvakuolen ausgezeichnet, während beim Männchen in einem kompakten Cytoplasma zunehmend größere, deutlich begrenzte Vakuolen auftreten. Im Blindversuch gelingt aufgrund dieser Kriterien die Geschlechtsdiagnose mit großer Treffsicherheit. Nach histometrischen Untersuchungen sind die weiblichen Fasciculatakerne größer als die männlichen. Bei größerem Zellvolumen ist die Kernzahl/Flächeneinheit beim Weibchen von der Pubertät an kleiner. Die Glomerulosa und die inneren Rindenschichten zeigen keine Geschlechtsdifferenzen. Fermenthistochemisch ist eine Geschlechtsdifferenz nicht nachweisbar. Die relative Zellhypertrophie in der Fasciculata der weiblichen Nebennierenrinde ist das morphologische Äquivalent eines geschlechtsdifferenten Steroidmetabolismus bei der Ratte.
    Notes: Summary In 260 male and female Sprague-Dawley CD rats the sex dependent development of the adrenal cortex was studied histologically and by histometric procedures. Beginning in the 4th week of life the parenchymal cells in the fasciculata of the female animals are characterized by a light, finely granular cytoplasm without distinct lipid vacuoles. In the males, however, the cells show a dense, compact cytoplasm with clearly visible vacuoles increasing in size. In a blind test the sex diagnosis can be established with great accuracy. Histometrically the nuclei in the female fasciculata cells are larger than in the males. Furthermore, caused by a larger cell volume the number of nuclei per square unit is smaller in postpuberal females. The glomerulosa and the inner parts of the cortex do not show any sex differences, nor does enzyme histochemistry. The relative cellular hypertrophy in the fasciculata of the female adrenal cortex represents the morphologic equivalent of the sexual differences in the rats steroid metabolism.
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  • 82
    ISSN: 1432-0878
    Keywords: Nematosomes ; Subsynaptic web ; Microfilamentous cytoplasmic network ; Neurosecretory cells ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An electron microscope study of the rat supraoptic nucleus, substantia nigra, neostriatum and periventricular preoptic area demonstrates that nematosomes are present within the perikaryon of neurons located in these structures. The latter structure may be found in close association with the subsynaptic web of axosomatic synapses. Numerous micro-filaments fan out from the nematosome and link the latter organelle to the ribosomes, the cytoplasmic membranes and the plasma membrane thus establishing an interwoven filamentous cytoplasmic network. A possible close relationship between the nematosomes and the neurofilaments and neurotubules is discussed.
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  • 83
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    Cell & tissue research 118 (1971), S. 243-248 
    ISSN: 1432-0878
    Keywords: Arteriovenous anastomoses ; Valve mechanism ; Rat ; Skin of the paw
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung In der dorsalen Haut der Hinterpfoten von Ratten wurden Klappen am Abgang kleinerer Gefäße von großen Arterien beobachtet. Diese Arterien verlaufen in einer subkutanen, größere Gefäße und Nerven führenden Bindegewebsschichte über den Streckersehnen. Die kleineren Gefäße haben den Wandbau einer Vene und zweigen etwa im rechten Winkel von der Arterie ab. An ihrer Abgangsstelle ist neben den Klappen manchmal ein sphinkterartiger Muskelring ausgebildet. Diese Gefäßabschnitte werden für arterio-venöse Anastomosen gehalten und auf die Bedeutung solcher an dieser Stelle bisher nicht beschriebenen Verschlußeinrichtungen für die Regulation der Kurzschlüsse wird hingewiesen.
    Notes: Summary In the dorsal skin of the hindpaws of rats valves were observed at those sites where smaller vessels branched from larger arteries. These arteries run in a subcutaneous layer of connective tissue, which lies above the extensor tendons and in which the larger vessels and nerves are found. These smaller vessels, the walls of which resemble those of veins, were seen branching off at approximate right angles to their artery of origin. Besides the valves a sphincterlike muscle ring was observed in some cases at the point of branching. These vascular segments are held to be arteriovenous anastomoses. Such “locking devices” at these points have not been described until now and seem to be important in the regulation of arteriovenous shunts.
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  • 84
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    Cell & tissue research 121 (1971), S. 171-180 
    ISSN: 1432-0878
    Keywords: Nerve endings ; Epithelium ; Rat ; Electronmicroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Im Anschluß an frühere lichtmikroskopisch erhobene Befunde (Silberimprägnation; 1924, 1928) weist der Verfasser durch elektronenmikroskopische Untersuchungen nach, daß durch die Interzellularspalten des Epithels (Schnauze der weißen Ratte) Nervenfasern hindurchziehen. Diese Nervenfäserchen, ihre Varikositäten und ihre Endknöpfchen liegen in den Spalten zwischen den Epithelzellen. Die Ultrastruktur der nackten, d.h. von Schwannschen Zellen nicht umhüllten terminalen Nervenfasern und ihrer Endigungen im Epithel wird beschrieben.
    Notes: Summary In addition to former light microscopical observations the author demonstrates electronmicroscopically that nerve fibers pass through the intercellular spaces of the epithelium. The nerve fibers, their varicosities and terminal bulbs lie within the spaces between the epithelial cells. The ultrastructure of the terminal nerve fibers in the epithelium is described.
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  • 85
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    Cell & tissue research 121 (1971), S. 292-300 
    ISSN: 1432-0878
    Keywords: Tissue Mast Cells ; Rat ; Regeneration ; Monocytes ; Peritoneal Exudates ; Cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Regeneration von Gewebsmastzellen wurde durch Untersuchungen von Peritonealexsudat erwachsener Ratten verfolgt, die häufigen Spülungen der Bauchhöhle unterworfen wurden. Innerhalb von 4–6 Tagen kommt es zu einer starken Vermehrung unreifer Gewebszellen. Die Ausbildung von Alcianblau-positiven unreifen Granula in ungranulierten Vorstufen benötigt etwa 6 Std. Die Ausbildung von Safranin-positiven reifen Granula vollzieht sich in 48 Std. Die Ergebnisse der zytochemischen Untersuchungen unreifer Mastzellvorstufen sprechen für eine monozytogene Entstehung der Gewebsmastzellen.
    Notes: Summary In adult rats, the regeneration of tissue mast cells in peritoneal exudates was studied by repeated peritoneal lavages. After 4–6 days, tissue mast cells appeared in great numbers in peritoneal exudates. Alcian blue positive granules were first noted at 6 hrs in agranular mast cell precursors. Maturation with accumulation of safraninpositive granules was complete after 48 hrs. The cytochemical reactions of the earliest tissue mast cell precursors suggest a monocytogenic origin of tissue mast cells.
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  • 86
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    Berichte der deutschen chemischen Gesellschaft 104 (1971) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 87
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    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 21-30 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Diastereomers of Nonactin Acid and Epimers of 2-Desmethylnonactin AcidNonactin acid 8a was prepared in only four reaction steps starting from the furan 3a. - In an attempt to prepare nonactin acid by intramolecular cyclisation of 13, the tetrahydropyran 15 was obtained in addition to the desired tetrahydrofuran 14. Treatment of 14 + 15 with sodium cyanide under the conditions of the Kolbe reaction led to the formation of the isomeric acids 16 + 17.
    Notes: Ausgehend von dem Furan 3a gelangt man in vier Reaktionsschritten zur Nonactinsäure 8a, einem 2.5-disubstituierten Tetrahydrofuran. - Beim Versuch der Darstellung von Nonactinsäure durch intramolekulare Cyclisierung von 13 entstand neben dem gewünschten Tetrahydrofuran 14 durch Ringerweiterung auch das Tetrahydropyran 15. Die Umwandlung von 14 + 15 mit Natriumcyanid nach Kolbe führte zu den stellungsisomeren Säuren 16 + 17.
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  • 88
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    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 40-49 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Aromatic Solvent Induced Shifts (ASIS) in the N.M.R. Spectra of tert-Butyl-, tert-Butoxy-and Nitro(tert-butyl)benzene DerivativesThe n.m.r. spectra of aromatic tert-butyl and tert-butoxy groups which are not separated in CCl4 may always be resolved in benzene and pyridine solution. In some cases (e. g. 15) assignements for these signals are obtained empirically from their solvent shifts. The signals of the aromatic protons in 2.6- and 3.4-dinitro-1-tert-butylbenzene show remarkable solvent effects (CCl4→C6D6) which cannot be explained by the 1:1 complex models. The shifts induced by aromatic solvents must originate rather from the time average over all orientations of the anisotropic molecules in the nearest solvent schell. The interpretation of such solvent shifts should be based on values derived from an absolute standard.
    Notes: In CCl4 nicht getrennte NMR-Signale für aromatisch gebundene tert.-Butyl- und tert.-Butyloxygruppen werden in Benzol und Pyridin stets aufgelöst und können in bestimmten Fällen (z. B. 15) an Hand der Lösungsmittelabhängigkeit empirisch zugeordnet werden. Die Ringprotonensignale bei 2.6- und 3.4-Dinitro-1-tert.-butyl-benzol zeigen beim Lösungsmittelwechsel CCl4→C6D6 sehr unterschiedliche und z. T. sehr starke Verschiebungen, die nicht mit dem Modell spezifischer 1:1-Komplexe erklärt werden können. Die Wirkung des aromatischen Lösungsmittels muß vielmehr durch das Zeitmittel über alle Orientierungen aller anisotroper Moleküle in der engsten Solvathülle zustandekommen. Auf die Verwendung eines absoluten Standards bei der Deutung von Lösungsmitteleffekten in der NMR-Spektroskopie wird hingewiesen.
    Additional Material: 2 Tab.
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  • 89
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    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 473-478 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of 7-β-Neohesperidosyl-4′-(β-D-glucopyranosyl)naringenin, a Flavanone Triglycoside from Citrus FruitsThe glycoside 7-β-neohesperidosyl-4′-(β-D-glucopyranosyl)naringenin (3), isolated from the segments of Citrus paradisi Macf, by Mizelle et al., was synthesized by condensation of phloracetophenone 4-β-neohesperidoside (1) with 4-hydroxybenzaldehyde 4-β-D-glucopyranoside (2) and by cyclisation of the resulting chalkone glykoside. Dehydrogenation of the flavanone triglykoside undecaacetate and subsequent saponification leads to the formation of 7-β-neohesperidosyl-4′-(β-D-glucopyranosyl)apigenin (7), the first synthetic apigenin triglycoside.
    Notes: Das von Mizelle und Mitarbb. aus Citrus paradisi Macf. isolierte 7-β-Neohesperidosyl-4′-β-D-glucopyranosyl-naringenin (3) wurde durch Kondensation von Phloracetophenon-4-β-neohesperidosid (1) mit 4-Hydroxy-benzaldehyd-4-β-D-glucopyranosid (2) und Cyclisierung des entstandenen Chalkonglykosids synthetisiert. Durch Dehydrierung des Flavanontriglykosid-undecaacetats (3a) wurde nach Verseifen das 7-β-Neohesperidosyl-4′-β-D-glucopyranosyl-apigenin (7) als erstes synthetisches Apigenintriglykosid dargestellt.
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  • 90
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Theoretical and Spectroscopic Investigations of Indigo Dyes, XI. Compounds with the Basic Chromophore of Thioindigo: Preparation and Properties of 3.4-Bis(alkylthio)hex-3-ene-2.5-dionesThe nucleophilic exchange of halogen in trans-3.4-dibromo- and -3.4-dichlorohex-3-ene-2.5-dione (4 and 5) with alkanethiols is studied. With bromine as leaving group substitution and reductive debromination leads to the formation of trans-3-methylthiohex-3-ene-2.5-dione (7a). With chlorine the expected trans-3.4-bis(alkylthio)hex-3-ene-2.5-diones (6a-c) are formed. These have the same structure and geometry as the basic chromophore of thioindigo, but they do not show the corresponding typical chemical and spectroscopic properties. They rather behave spectroscopically like β-alkylthio-α,β-unsaturated ketones. Conformation and spectroscopic properties of 6a-e are discussed with respect to the sterical requirements of the different groups at the sulfur atoms.
    Notes: Der Austausch der beiden Halogenatome von trans-3.4-Dibrom- und -3.4-Dichlor-hexen-(3)-dion-(2.5) (4 und 5) gegen Alkylmercaptane wird untersucht. Mit Brom als Abgangsgruppe erfolgt neben einfachem Austausch quantitativ eine reduktive Entbromierung zu trans-3-Methylmercapto-hexen-(3)-dion-(2.5) (7a), während mit Chlor als Abgangsgruppe zweifacher Austausch zu trans-3.4-Bis-alkylmercapto-hexen-(3)-dionen-(2.5) (6a-e) stattfindet. Diese zeigen nicht die spektroskopischen und chemischen Eigenschaften, die man für dieses - in der Verknüpfung ihrer funktionellen Gruppen dem Thioindigogrundchromophor entsprechende - System erwartet, sondern sie verhalten sich wie einfache β-alkylmercapto-α,β-ungesättigte Ketone. Die Abhängigkeit der Konformation und der spektroskopischen Eigenschaften von der Größe der Alkylreste am Schwefel wird diskutiert.
    Additional Material: 4 Ill.
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  • 91
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    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 549-557 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Boron, LIV. Chemical Properties of Tris(2.2-dimethylhydrazino)boraneIn contrast to the ready cleavage of BN-bonds in tris(dialkylamino)boranes by BCl3, (BH3)2, HCl or CH3J the prefered reactions of these acids with tris(2.2-dimethylhydrazino)borane (1) are additions. Due to the greater basicity of the dimethylamino group as compared to the NH moiety, additions occur at the group (CH3)2N before the group NH is attacked. Solvolysis of B[NH—N(CH3)2]3 (1) by H2O or C2H5OH yields (CH3)2 N—NH2 and B(OH)3 or B(OC2H5)3, respectively, but no mixed compounds XnB[NH—N(CH3)2]3 n are formed in these reactions or by ligand exchange with B(OCH3)3 or B[N(CH3)2]3. 1 is stable up to 280° at higher temperature condensation with formation of N.N-dimethylhydrazine occurs.
    Notes: Während die Verbindungen BCl3, (BH3)2, HCl und CH3J die B N-Bindungen von Tris(dialkylamino)-boranen spalten, lagern sie sich an Tris(2.2-dimethyl-hydrazino)-boran (1) an. Dabei erfolgt zunächst Addition an die stärker basische Dimethylaminogruppe, danach reagiert auch die schwächer basische NH-Gruppe. Solvolysen von 1 mit H2O und C2H5OH oder Komproportionierungen mit B(OCH3)3 oder B[N(CH3)2]3 führen nicht zu gemischten Verbindungen XnB[NH—N(CH3)2]3 n(X—OH, OR, N(CH3)2). Im Vergleich zu Tris(alkylamino)-boranen ist 1 thermisch sehr stabil. Erst oberhalb 280° spaltet sich N,N-Dimethylhydrazin ab.
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  • 92
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    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 605-638 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: o- and p-(Dicyanomethylene)quinocyclopropenes. Synthesis, Mechanisms of Formation and Propertieso- and p-quinocyclopropenes of the benzene, naphthalene, anthracene, phenanthrene, and fluorene series (9, 12-15, 29, 30b, 37, 38) are prepared a) by thermolysis of 1:1 adducts of 3-ethoxy-1.2-diaryl-cyclopropenylium cations 6 and arylmalodinitrile anions, b) by reaction of diarylcyclopropenones with arylmalodinitriles in acetic anhydride. The reaction mechanisms suggested by isolation of intermediates are discussed. - Polarography of the quinocyclopropenes shows reversible formation of a radical cation in a one-electron step. This is in agreement with calculations according to the simple HMO model, which give satisfactory correlations with polarography, u. v. and i. r. spectroscopical data.
    Notes: o- und p-Chinocyclopropene der Benzol-, Naphthalin-, Anthracen-, Phenanthren- und Fluorenreihe (9, 12-15, 29, 30b, 37, 38) werden dargestellt a) durch Thermolyse von 1:1-Addukten aus 3-Äthoxy-1.2-diaryl-cyclopropenylium-Kationen 6 und Arylmalodinitril-Anionen, b) durch Reaktion von Diarylcyclopropenonen und Arylmalodinitrilen in Acetanhydrid. Die sich aus der Isolierung von Zwischenprodukten ergebenden Reaktionsmechanismen werden diskutiert. - Durch polarographische Untersuchungen wird festgestellt, daß die Chinocyclopropene reversibel im Einelektronenschritt in ein Radikal-Kation übergehen. Dies wird durch Rechnungen nach dem einfachen HMO-Modell bestätigt, die befriedigende Korrelationen mit den polarographischen sowie UV- und IR-spektroskopischen Daten ergeben.
    Additional Material: 5 Ill.
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  • 93
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    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 665-667 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 94
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    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 668-670 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 95
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 71-74 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on the Bromination of Hydrocarbons in Liquid BromineThe bromination of aliphatic hydrocarbons in liquid bromine in the presence of catalytic amounts of hydrobromic acid is described. Hydrocarbons with neighbouring tertiary carbon atoms and tetraalkylated ethylenes give definite bromination products. From the corresponding hydrocarbons were obtained 1.4-Dibromo-2.3-bis(bromomethyl)but-2-ene (1), 1.4.5-Tribromo-2.3-bis(bromomethyl)pent-2-ene (2), 1.4.5-Tribromo-2.3-bis(bromomethyl)-hex-2-ene (3), 1.4.5-Tribromo-2-bromomethyl-3-(α.β-dibromoethyl)pent-2-ene (4), and 1.4.5.8-Tetrabromo-Δ4a(8a)-octalin (5).
    Notes: Bei der Bromierung in flüssigem Brom in Gegenwart katalytischer Mengen Bromwasserstoffsäure bilden aliphatische Kohlenwasserstoffe mit benachbarten tertiären Kohlenstoffatomen und tetraalkylierte Äthylene definierte Bromierungsprodukte. Im einzelnen werden 1.4-Dibrom-2.3-bis-brommethyl-buten-(2) (1), 1.4.5-Tribrom-2.3-bis-brommethyl-penten-(2) (2), 1.4.5-Tribrom-2.3-bis-brommethyl-hexen-(2) (3), 1.4.5-Tribrom-2-brommethyl-3-[α.β-dibromäthyl]-penten-(2) (4) und 1.4.5.8-Tetrabrom-Δ4a(8a)-octalin (5) aus den entsprechenden Kohlenwasserstoffen erhalten.
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  • 96
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 110-130 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Complex Chemistry of Four-Centre π-Systems, III. Colour, Solvatochromy and Reduction Potentials of (1.4-Diazabutadiene)molybdenum TetracarbonylsMolybdenum tetracarbonyl complexes of the =N=C=C=N-system (1,4-diazabutadiene=DAB) show an intense, low energy electronic transition, which is antiparallel to the ground state dipole moment; its solvent dependance is measured for 33 mostly new compounds and shows directly the amount of metal-ligand interaction, and thus of π-backbonding. The π-delocalisation of metal-D-electrons strongly depends on the substituents of the DAB-system, but the complex ground state has still molybdenum in the valence state 0. The competing mesomeric, inductiv and steric effects of the DAB ligands can be separated, too, by polarographic reduction potentials of complexes and ligands. The results can be understood in terms of simple perturbation theory.
    Notes: Molybdäncarbonyl-Komplexe des =N=C=C=N-Systems (1.4-Diaza-butadien=DAB) zeigen eine antiparallel zum Grundzustandsdipolmoment gerichtete intensive farbgebende Elektronenanregung, deren an dreiunddreißig meist neuen Verbindungen untersuchte Solvatochromie direkte Aussagen über die Größe der Metall-Ligand-Termwechselwirkung und damit über die π-Rück bindung gestattet. Die Delokalisierung der Metall-D-Elektronen ist abhängig von den Substituenten des DAB-Systems, der Komplexgrundzustand enthält aber formal 0-wertiges Molybdän. Die konkurrierenden induktiven, mesomeren und sterischen Effekte der DAB-Liganden sind in den polarographischen Reduktionspotentialen der Komplexe und Liganden selbst ebenfalls genau abgrenzbar, bestätigen die Solvatochromie-untersuchungen und lassen sich im Rahmen einfacher Störungstheorie widerspruchsfrei deuten.
    Additional Material: 7 Ill.
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  • 97
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    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 138-144 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reductive Silylation of NaphthaleneThe reaction of naphthalene with trimethylchlorosilane and sodium has been found to afford 1.4-bis(trimethylsilyl)-1.4-dihydro- and 1.2-bis(trimethylsilyl)-1.2-dihydronaphthalene (1, 2), whereas potassium reacts to give mainly 1.2.3.7-tetrakis(trimethylsilyl)-1.2.3.4-tetrahydro-naphthalene (3) besides 1.2.4-tris(trimethylsilyl)-1.4-dihydro-(4) and 1.2.4-tris(trimethylsilyl)-1.2-dihydronaphthalene (5). The configuration has been determined by n.m.r. spectroscopy.
    Notes: Bei der reduktiven Silylierung von Naphthalin mit Natrium und Trimethylchlorsilan werden vorwiegend nur 1.4-Bis-trimethylsilyl-1.4-dihydro- und 1.2-Bis-trimethylsilyl-1.2-dihydronaphthalin (1, 2) gebildet. Ersetzt man jedoch das Natrium durch Kalium, so erhält man 1.2.4-Tris-trimethylsilyl-1.4-dihydro- (4) sowie 1.2.4-Tris-trimethylsilyl-1.2-dihydro-naphthalin (5) und vor allem 1.2.3.7-Tetrakis-trimethylsilyl-1.2.3.4-tetrahydro-naphthalin (3). - Die Aufklärung der Konfiguration erfolgte NMR-spektroskopisch.
    Additional Material: 2 Tab.
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  • 98
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    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 168-172 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Properties of 4-Chloro- and 4-Bromo-2H-chromenes and of 3-Bromo-2H-chromenesDehydrobromination of trans-3,4-dihalochromans yields the 4-halo-2H-chromenes 1-4. Dehydration of cis-3-bromo-4-hydroxychromans leads to the 3-bromo-2H-chromenes 5 and 6.
    Notes: Durch Abspaltung von Bromwasserstoff entstehen aus den trans-3.4-Dihalogen-chromanen die entsprechenden 4-Halogen-2H-chromene 1-4. Die 3-Brom-2H-chromene 5 und 6 erhält man durch Dehydratisierung der cis-3-Brom-4-hydroxy-chromane.
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  • 99
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 210-219 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Vinylogous Acyl Compounds, IX. Hydrolysis of Vinylogous Carbonamidium SaltsThe hydrolysis of vinylogous carbonamidium salts 10 in aqueous sodium hydrogen carbonate solution does not lead - as hitherto supposed - to meso-(2-acylvinyl)acylacetaldehydes 8, but to bis(2-acylvinyl)ethers 11. The structure of these compounds results from n. m. r. and i. r. spectra and is confirmed by independent synthesis.
    Notes: Die Hydrolyse vinyloger Carbonamidiumsalze 10 in wäßriger Natriumhydrogencarbonat-Lösung führt nicht - wie bisher angenommen - zu meso-[2-Acyl-vinyl]-acylacetaldehyden 8, sondern zu Bis-[2-acyl-vinyl]-äthern 11. Die Strukturzuordnung dieser Verbindungen gründet sich auf NMR- und IR-spektroskopische Befunde sowie auf eine unabhängige synthese.
    Additional Material: 3 Tab.
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  • 100
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 160-167 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1.2.3-Tricarbonyl Compounds, V. Hydrate-forming 1.2.3-Tricarbonyl Compounds as Dienophiles in Diels-Alder ReactionsThe 1.2.3-tricarbonyl compounds 5-8 react as dienophiles and add isoprene or 2.3-dimethylbuta-1.3-diene to yield the spiro-dihydropyranes 9-16. I.r., mass, and n.m.r. spectra are discussed.
    Notes: Cyclische 1.2.3-Tricarbonylverbindungen (vgl. 5-8) reagieren als Dienophile mit Isopren und 2.3-Dimethyl-butadien-(1.3) unter Bildung der Spiro-dihydropyrane 9-16. Die IR- und Massenspektren der Reaktionsprodukte sowie die NMR-Spektren von 9 und 10 werden diskutiert.
    Additional Material: 2 Tab.
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