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  • 2000-2004  (57)
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  • 1
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    Vorhaben: Offene Navigation und Suchmaschinen in Verbünden, Konsortien und den Wissenschaften; Schlussbericht zumTeilprojekt des BMBF-Vorhabens: Kompetenznetzwerk NeueDienste, Standardisierung, Metadaten. (2004)
    Details
    Publikationsdatum: 2020-03-23
    Beschreibung: Die harmonische Integration der Navigation und Suche in lizenzierten Journalen und gleichzeitig in freien digitalen Dokumenten unter einer einheitlichen konsistenten Nutzeroberflache ist eines der ungelösten F&E-Probleme der Fachinformation. Hierfür sollen Elemente des Invisible Web und des Visible Web unter Berücksichtigung offener Standards nahtlos #I miteinander verbunden werden. Dem Projekt liegt ein Modell mit Internet-Index, Metasuche und Open Linking über verteilten heterogenen Speichern #I zu Grunde: Verschiedenste Server, digitale Referenzen in Artikeln und Dokumenten, Links in Datenbanken und auf Bestelldienste sollen unter Berücksichtigung von Standort-, Studien- und Lernbedingungen kooperativ miteinander vernetzt werden. Die Leistungsfähigkeit des Modells soll in Pilotimplementierungen getestet und für eine breite Anwendung vorbereitet werden. Auf dieser Basis soll das Vorhaben Verteilter Zeitschriftenserver der AG der Verbundsysteme in eigenen Teilprojekten kooperativ initiiert werden, das jetzt in das Vorhaben Verteilter Dokumentenserver von vascoda integriert ist.
    Schlagwort(e): ddc:000
    Sprache: Deutsch
    Materialart: reportzib , doc-type:preprint
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  • 2
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    Parameter Estimation and Accuracy Matching Strategies for 2-D Reactor Models (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: The mathematical modeling of a special modular catalytic reactor kit leads to a system of partial differential equation in two space dimensions. As customary, this model contains unconfident physical parameters, which may be adapted to fit experimental data. To solve this nonlinear least squares problem we apply a damped Gauss-Newton method. A method of lines approach is used to evaluate the associated model equations. By an a priori spatial discretization a large DAE system is derived and integrated with an adaptive, linearly-implicit extrapolation method. For sensitivity evaluation we apply an internal numerical differentiation technique, which reuses linear algebra information from the model integration. In order not to interfere the control of the Gauss-Newton iteration these computations are done usually very accurately and, therefore, very costly. To overcome this difficulty, we discuss several accuracy adaptation strategies, e.g., a master-slave mode. Finally, we present some numerical experiments.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 3
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    Finding All Maximal Cliques of a Family of Induced Subgraphs (2004)
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    Publikationsdatum: 2020-03-06
    Beschreibung: Many real world problems can be mapped onto graphs and solved with well-established efficient algorithms studied in graph theory. One such problem is to find large sets of points satisfying some mutual relationship. This problem can be transformed to the problem of finding all cliques of an undirected graph by mapping each point onto a vertex of the graph and connecting any two vertices by an edge whose corresponding points satisfy our desired relationship. Clique detection has been widely studied and there exist efficient algorithms. In this paper we study a related problem, where all points have a set of binary attributes, each of which is either 0 or 1. This is only a small limitation, since all discrete properties can be mapped onto binary attributes. In our case, we want to find large sets of points not only satisfying some mutual relationship; but, in addition, all points of a set also need to have at least one common attribute with value 1. The problem we described can be mapped onto a set of induced subgraphs, where each subgraph represents a single attribute. For attribute $i$, its associated subgraph contains those vertices corresponding to the points with attribute $i$ set to 1. We introduce the notion of a maximal clique of a family, $\mathcal{G}$, of induced subgraphs of an undirected graph, and show that determining all maximal cliques of $\mathcal{G}$ solves our problem. Furthermore, we present an efficient algorithm to compute all maximal cliques of $\mathcal{G}$. The algorithm we propose is an extension of the widely used Bron-Kerbosch algorithm.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 4
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    An Integer Programming Model for Multi-Layer Network Design (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: We present an integer linear programming model for the design of multi-layer telecommunication networks. The formulation integrates hardware, capacity, routing, and grooming decisions in \emph{any} n umber of network layers. Practical hardware restrictions and cost can accurately be taken into account for technologies based on connection-oriented routing protocols.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 5
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    Compressing Triangle Meshes using Geometric Infomation (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: We introduce FreeLence, a lossless single-rate connectivity compression algorithm for triangle surface meshes. Based upon a geometry-driven traversal scheme we present two novel and simple concepts: free-valence connectivity encoding and entropy coding based on geometric context. Together these techniques yield significantly smaller rates for connectivity compression than current state of the art approaches - valence-based algorithms and Angle- Analyzer, with an average of $36\%$ improvement over the former and an average of $18\%$ over the latter on benchmark 3D models, combined with the ability to well adapt to the regularity of meshes. We also prove that our algorithm exhibits a smaller worst case entropy for a class of "'well-behaved"' triangle meshes than valence-driven connectivity encoding approaches.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 6
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    Jahresbericht 2003 (2004)
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    Publikationsdatum: 2019-10-24
    Schlagwort(e): ddc:000
    Sprache: Deutsch
    Materialart: annualzib , doc-type:report
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  • 7
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    Large-scale hierarchical networks: How to compute an optimal architecture? (2004)
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    Publikationsdatum: 2020-02-11
    Beschreibung: In this article, we present a mathematical model and an algorithm to support one of the central strategic planning decisions of network operators: How to organize a large number of locations into a hierarchical network? We propose a solution approach that is based on mixed-integer programming and Lagrangian relaxation techniques. As major advantage, our approach provides not only solutions but also worst-case quality guarantees. Real-world scenarios with more than 750 locations have been solved within 30 minutes to less than 1\% off optimality.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 8
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    UMTS Radio Network Evaluation and Optimization beyond Snapshots (2004)
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    Publikationsdatum: 2020-02-11
    Beschreibung: This paper is concerned with UMTS radio network design. Our task is to reconfigure antennas and the related cells as to improve network quality. In contrast to second generation GSM networks, \emph{interference} plays a paramount role when designing third generation radio networks. A known compact formulation for assessing the interference characteristics of a radio network as coupling relations between cells based on user snapshots is generalized to statistical average load. This enables us to overcome the notorious difficulties of snapshot-based network optimization approaches. We recall a mixed-integer programming model for the network design problem that is based on user snapshots and contrast it with a new network design model based on the average coupling formulation. Exemplarily focusing on the important problem of optimizing antenna tilts, we give computational results for a fast local search algorithm and the application of a MIP solver to both models. These results demonstrate that our new average-based approaches outperform state-of-the-art snapshot models for UMTS radio network optimization.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 9
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    SCIP - a framework to integrate Constraint and Mixed Integer Programming (2004)
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    Publikationsdatum: 2021-08-05
    Beschreibung: Constraint Programs and Mixed Integer Programs are closely related optimization problems originating from different scientific areas. Today's state-of-the-art algorithms of both fields have several strategies in common, in particular the branch-and-bound process to recursively divide the problem into smaller sub problems. On the other hand, the main techniques to process each sub problem are different, and it was observed that they have complementary strenghts. We propose a programming framework {\sffamily SCIP} that integrates techniques from both fields in order to exploit the strenghts of both, Constraint Programming and Mixed Integer Programming. In contrast to other proposals of recent years to combine both fields, {\sffamily SCIP} does not focus on easy implementation and rapid prototyping, but is tailored towards expert users in need of full, in-depth control and high performance.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 10
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    Searching and Classifying Differential Equations on the Web (2004)
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    Publikationsdatum: 2018-12-06
    Beschreibung: In this paper we describe the semantic analysis of differential equations given in the ubiquitous semi-structured formats MathML and OpenMath. The analysis is integrated in a deployed Web indexing framework. Starting from basic classifications for differential equations the proposed system architecture is amenable to extensions for further reconstruction of mathematical content on the Web. The syntactic analysis of mathematical formulae given in the considered formats must overcome ambiguities that stem from the fact that formula particles may have different encodings, which are in principle completely arbitrary. However, it turns out that the syntactic analysis can be done straightforward given some natural heuristic assumptions.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 11
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    Anisotropic Filtering of Non-Linear Surface Features (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: A new method for noise removal of arbitrary surfaces meshes is presented which focuses on the preservation and sharpening of non-linear geometric features such as curved surface regions and feature lines. Our method uses a prescribed mean curvature flow (PMC) for simplicial surfaces which is based on three new contributions: 1. the definition and efficient calculation of a discrete shape operator and principal curvature properties on simplicial surfaces that is fully consistent with the well-known discrete mean curvature formula, 2. an anisotropic discrete mean curvature vector that combines the advantages of the mean curvature normal with the special anisotropic behaviour along feature lines of a surface, and 3. an anisotropic prescribed mean curvature flow which converges to surfaces with an estimated mean curvature distribution and with preserved non-linear features. Additionally, the PMC flow prevents boundary shrinkage at constrained and free boundary segments.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 12
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    Function space interior point methods for PDE constrained optimization (2004)
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    Publikationsdatum: 2019-01-29
    Beschreibung: A primal-dual interior point method for optimal control problems with PDE constraints is considered. The algorithm is directly applied to the infinite dimensional problem. Existence and convergence of the central path are analyzed. Numerical results from an inexact continuation method applied to a model problem are shown.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 13
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    Zusammenarbeit mit vascoda im Rahmen des Verteilten Dokumentenservers (VDS) (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: Die in der Arbeitsgemeinschaft der Verbundsysteme zusammengeschlossenen deutschen Verbundsysteme kooperieren zur Realisierung eines die Länder und Verbundregionen übergreifenden offenen Netzwerkes einer offenen digitalen Bibliothek, dem Verteilten Dokumentenserver (VDS). Wesentliche Bestandteile des VDS sind die in den lokalen Bibliotheken und Verbundsystemen verteilten Dokumentenspeicher. Beim Aufbau des VDS verfolgen die deutschen Verbundsysteme für ihre digitalen Ressourcen, Zeitschriften und Dokumente, folgende Ziele [AGV03]: \begin{itemize} \item{Erhalt und dauerhafte Sicherung einmal erworbener Rechte} \item{Bessere Erschließung und Integration in das eigene Angebot} \item{Nahtlose Navigation in lokalen Zeitschriften- und Dokumentenservern und zwischen digitalen Artikeln und Zeitschriften, Dokumenten und Servern} \item{Dauerhafte Sicherung des Zugriffs und perspektivisch Langzeitverfügbarkeit} \end{itemize} Die Verbundsysteme streben an, die Speicherung, Erschließung und das Angebot ihrer digitalen Materialien in einer nationalen Kooperation durchzuführen. Sie entwickeln und betreiben zu diesem Zweck Portal- und Querschnittstechnologien zur Integration ihrer dezentral gespeicherten digitalen Ressourcen mittels Internet-Technologien.
    Schlagwort(e): ddc:000
    Sprache: Deutsch
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  • 14
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    Utility Proportional Fair Bandwidth Allocation - An Optimization Oriented Approach (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: In this paper, we present a novel approach to the congestion control and resource allocation problem of elastic and real-time traffic in telecommunication networks. With the concept of utility functions, where each source uses a utility function to evaluate the benefit from achieving a transmission rate, we interpret the resource allocation problem as a global optimization problem. The solution to this problem is characterized by a new fairness criterion, \e{utility proportional fairness}. We argue that it is an application level performance measure, i.e. the utility that should be shared fairly among users. As a result of our analysis, we obtain congestion control laws at links and sources that are globally stable and provide a utility proportional fair resource allocation in equilibrium. We show that a utility proportional fair resource allocation also ensures utility max-min fairness for all users sharing a single path in the network. As a special case of our framework, we incorporate utility max-min fairness for the entire network. To implement our approach, neither per-flow state at the routers nor explicit feedback beside ECN (Explicit Congestion Notification) from the routers to the end-systems is required.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 15
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    Die Mathematik der kürzesten Wege. Inhalte und Methoden für den Unterricht (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: Wie findet man den optimalen Weg im U-Bahnnetz? Das Problem wird als Graph modelliert und dann eine Breitensuche durchgeführt. Will man Weglängen oder Fahrzeiten mitberücksichtigen, so braucht man den Algorithmus von Dijkstra für gewichtige Graphen. Beim Nachdenken über diese Algorithmen werden auch Fragestellungen der Graphentheorie berührt. In einem zweiten Abschnitt werden methodische Hinweise für den Unterricht in der Sekundarstufe I und II gegeben, insbesondere, wie man Lernende dazu bringen kann, ihre Ideen für Algorithmen präzise zu analysieren und zu Papier zu bringen.
    Schlagwort(e): ddc:000
    Sprache: Deutsch
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  • 16
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    Perron Cluster Analysis and Its Connection to Graph Partitioning for Noisy Data (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: The problem of clustering data can be formulated as a graph partitioning problem. Spectral methods for obtaining optimal solutions have reveceived a lot of attention recently. We describe Perron Cluster Cluster Analysis (PCCA) and, for the first time, establish a connection to spectral graph partitioning. We show that in our approach a clustering can be efficiently computed using a simple linear map of the eigenvector data. To deal with the prevalent problem of noisy and possibly overlapping data we introduce the min Chi indicator which helps in selecting the number of clusters and confirming the existence of a partition of the data. This gives a non-probabilistic alternative to statistical mixture-models. We close with showing favorable results on the analysis of gene expressi on data for two different cancer types.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 17
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    Linear Programming Lower Bounds for Minimum Converter Wavelength Assignment in Optical Networks (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: In this paper, we study the conflict-free assignment of wavelengths to lightpaths in an optical network with the opportunity to place wavelength converters. To benchmark heuristics for the problem, we develop integer programming formulations and study their properties. Moreover, we study the computational performance of the column generation algorithm for solving the linear relaxation of the most promising formulation. In many cases, a non-zero lower bound on the number of required converters is generated this way. For several instances, we in fact prove optimality since the lower bound equals the best known solution value.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 18
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    On PDE Solution in Transient Optimization of Gas Networks (2004)
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    Publikationsdatum: 2021-02-01
    Beschreibung: Operative planning in gas distribution networks leads to large-scale mixed-integer optimization problems involving a hyperbolic PDE defined on a graph. We consider the NLP obtained under prescribed combinatorial decisions---or as relaxation in a branch and bound framework, addressing in particular the KKT systems arising in primal-dual interior methods. We propose a custom solution algorithm using sparse local projections, based on the KKT systems' structual properties induced by the discretized gas flow equations in combination with the underlying network topology. The numerical efficiency and accuracy of the algorithm are investigated, and detailed computational comparisons with a control space method and with the multifrontal solver MA27 are provided.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 19
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    Optimization Models for Operative Planning in Drinking Water Networks (2004)
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    Publikationsdatum: 2021-02-01
    Beschreibung: The topic of this paper is minimum cost operative planning of pressurized water supply networks over a finite horizon and under reliable demand forecast. Since this is a very hard problem, it is desirable to employ sophisticated mathematical algorithms, which in turn calls for carefully designed models with suitable properties. The paper develops a nonlinear mixed integer model and a nonlinear programming model with favorable properties for gradient-based optimization methods, based on smooth component models for the network elements. In combination with further nonlinear programming techniques (to be reported elsewhere), practically satisfactory near-optimum solutions even for large networks can be generated in acceptable time using standard optimization software on a PC workstation. Such an optimization system is in operation at Berliner Wasserbetriebe.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 20
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    Unterrichtsideen zu Algorithmen der kombinatorischen Optimierung (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: Im Rahmen von Problemstellungen der kombinatorischen Optimierung können Schülerinnen und Schüler lernen, Algorithmen selber zu entwickeln. Gleichzeitig lernen sie dabei moderne Mathematik in ihren Anwendungen kennen und erleben die Mathematik als lebendige Wissenschaft.
    Schlagwort(e): ddc:000
    Sprache: Deutsch
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  • 21
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    Computing Optimal Morse Matchings (2004)
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    Publikationsdatum: 2020-12-15
    Beschreibung: Morse matchings capture the essential structural information of discrete Morse functions. We show that computing optimal Morse matchings is NP-hard and give an integer programming formulation for the problem. Then we present polyhedral results for the corresponding polytope and report on computational results.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 22
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    Provably Good Solutions for Wavelength Assignment in Optical Networks (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: In this paper, we study the minimum converter wavelength assignment problem in optical networks. To benchmark the quality of solutions obtained by heuristics, we derive an integer programming formula tion by generalizing the formulation of Mehrotra and Trick (1996) for the vertex coloring problem. To handle the exponential number of variables, we propose a column generation approach. Computational experiments show that the value of the linear relaxation states a good lower bound and can often prove optimality of the best solution generated heuristically.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 23
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    A Note on Contraction Degeneracy (2004)
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    Publikationsdatum: 2014-11-10
    Beschreibung: The parameter contraction degeneracy -- the maximum minimum degree over all minors of a graph -- is a treewidth lower bound and was first defined in (Bodlaender, Koster, Wolle, 2004). In experiments it was shown that this lower bound improves upon other treewidth lower bounds. In this note, we examine some relationships between the contraction degeneracy and connected components of a graph, block s of a graph and the genus of a graph. We also look at chordal graphs, and we study an upper bound on the contraction degeneracy and another lower bound for treewidth. A data structure that can be used for algorithms computing the degeneracy and similar parameters, is also described.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 24
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    On the Maximum Cardinality Search Lower Bound for Treewidth (2004)
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    Publikationsdatum: 2014-11-10
    Beschreibung: The Maximum Cardinality Search algorithm visits the vertices of a graph in some order, such that at each step, an unvisited vertex that has the largest number of visited neighbors becomes visited. An MCS-ordering of a graph is an ordering of the vertices that can be generated by the Maximum Cardinality Search algorithm. The visited degree of a vertex $v$ in an MCS-ordering is the number of neighbors of $v$ that are before $v$ in the ordering. The visited degree of an MCS-ordering $\psi$ of $G$ is the maximum visited degree over all vertices $v$ in $\psi$. The maximum visited degree over all MCS-orderings of graph $G$ is called its {\em maximum visited degree}. Lucena (2003) showed that the treewidth of a graph $G$ is at least its maximum visited degree. We show that the maximum visited degree is of size $O(\log n)$ for planar graphs, and give examples of planar graphs $G$ with maximum visited degree $k$ with $O(k!)$ vertices, for all $k\in \Bbb{N}$. Given a graph $G$, it is NP-complete to determine if its maximum visited degree is at least $k$, for any fixed $k\geq 7$. Also, this problem does not have a polynomial time approximation algorithm with constant ratio, unless P=NP. Variants of the problem are also shown to be NP-complete. We also propose and experimentally analyses some heuristics for the problem. Several tiebreakers for the MCS algorithm are proposed and evaluated. We also give heuristics that give upper bounds on the value of the maximum visited degree of a graph, which appear to give results close to optimal on many graphs from real life applications.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 25
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    A new Model for the Free Energy of Solvation and its Application in Protein Ligand Scoring (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: A new and time efficient model to evaluate the free energy of solvation has been developed. The solvation free energy is separated into an electrostatic term, a hydrogen bond term, and a rest-term, combining both entropic and van der Waals effects. The electrostatic contribution is evaluated with a simplified boundary element method using the partial charges of the MMFF94 force field. The number of hydrogen bonds and the solvent excluded surface area over the surface atoms are used in a linear model to estimate the non-electrostatic contribution. This model is applied to a set of 213 small and mostly organic molecules, yielding an rmsd of 0.87kcal/mol and a correlation with experimental data of r=0.951. The model is applied as a supplementary component of the free energy of binding to estimate binding constants of protein ligand complexes. The intermolecular interaction energy is evaluated by using the MMFF94 force field.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 26
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    Multiple Semi-flexible 3D Superposition of Drug-sized Molecules (2004)
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    Publikationsdatum: 2020-03-06
    Beschreibung: In this paper we describe a new algorithm for multiple semi-flexible superpositioning of drug-sized molecules. The algorithm identifies structural similarities of two or more molecules. When comparing a set of molecules on the basis of their three-dimensional structures, one is faced with two main problems. (1) Molecular structures are not fixed but flexible, i.e., a molecule adopts different forms. To address this problem, we consider a set of conformers per molecule. As conformers we use representatives of conformational ensembles, generated by the program ZIBMol. (2) The degree of similarity may vary considerably among the molecules. This problem is addressed by searching for similar substructures present in arbitrary subsets of the given set of molecules. The algorithm requires to preselect a reference molecule. All molecules are compared to this reference molecule. For this pairwise comparison we use a two-step approach. Clique detection on the correspondence graph of the molecular structures is used to generate start transformations, which are then iteratively improved to compute large common substructures. The results of the pairwise comparisons are efficiently merged using binary matching trees. All common substructures that were found, whether they are common to all or only a few molecules, are ranked according to different criteria, such as number of molecules containing the substructure, size of substructure, and geometric fit. For evaluating the geometric fit, we extend a known scoring function by introducing weights which allow to favor potential pharmacophore points. Despite considering the full atomic information for identifying multiple structural similarities, our algorithm is quite fast. Thus it is well suited as an interactive tool for the exploration of structural similarities of drug-sized molecules.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 27
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    Data Management for Processing Molecules (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: Molecular dynamics simulations of possible ligands for proteins yield large amounts of data in the form of trajectories which are further processed in order to find metastable conformations. These conformations can then be used for docking between ligand and protein. Around this core computation procedure lots of other data have to be managed. It should also be possible for external users not involved in program development to perform computations. As a paradigm for other fields where a similar constitution of program usage and data processing is found we present a software architecture for data generation, access and management. Requirements for this system include: Ease of use, graphical user interface, persistent storage of data concerning molecules, users, programs, program parameters, metadata, and results. A mere storage in the file system would render a quick overview of data more or less impossible. On the other hand, storing large amounts of binary data in a database doesn't yield any advantage concerning speed of access. Therefore, a hybrid approach combining file system and database is appropriate. The system should be easily extensible by inserting new applications which can be controlled and whose results can be collected and stored. The software system described here consists of different components, the presentation layer (graphical user interface), the business logic, the persistence layer (relational database plus file system), and an interface to the compute cluster (batch system for parallel processing). We will discuss the alternatives and take a closer look at the components.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 28
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    Visual Analysis of Molecular Conformations by Means of a Dynamic Density Mixture Model (2004)
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    Publikationsdatum: 2020-03-09
    Beschreibung: We propose an approach for transforming the sampling of a molecular conformation distribution into an analytical model based on Hidden Markov Models. The model describes the sampled shape density as a mixture of multivariate unimodal densities. Thus, it delivers an interpretation of the sampled density as a set of typical shapes that appear with different probabilities and are characterized by their geometry, their variability and transition probabilities between the shapes. The gained model is used to identify atom groups of constant shape that are connected by metastable torsion angles. Based on this description an alignment for the original sampling is computed. As it takes into account the different shapes contained in the sampled set, this alignment allows to compute reasonable average shapes and meaningful shape density plots. Furthermore, it enables us to visualize typical conformations.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 29
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    MOMENTUM Data Scenarios for Radio Network Planning and Simulation (Extended Abstract) (2004)
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    Publikationsdatum: 2020-02-11
    Beschreibung: We present publicly available data sets related to research on wireless networks. The scenarios contain a wide range of data and are detailed in all aspects. To our knowledge, this is the most realistic, comprehensive, and detailed \emph{public} data collection on mobile networking. We indicate example uses of this data collection in applications related tu UMTS.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 30
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    Models for Line Planning in Public Transport (2004)
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    Publikationsdatum: 2020-12-15
    Beschreibung: The \emph{line planning problem} is one of the fundamental problems in strategic planning of public and rail transport. It consists of finding lines and corresponding frequencies in a public transport network such that a given travel demand can be satisfied. There are (at least) two objectives. The transport company wishes to minimize its operating cost; the passengers request short travel times. We propose two new multi-commodity flow models for line planning. Their main features, in comparison to existing models, are that the passenger paths can be freely routed and that the lines are generated dynamically.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 31
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    Triangulated Manifolds with Few Vertices: Centrally Symmetric Spheres and Products of Spheres (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: The aim of this paper is to give a survey of the known results concerning centrally symmetric polytopes, spheres, and manifolds. We further enumerate nearly neighborly centrally symmetric spheres and centrally symmetric products of spheres with dihedral or cyclic symmetry on few vertices, and we present an infinite series of vertex-transitive nearly neighborly centrally symmetric 3-spheres.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 32
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    Anisotropic Simulation of the Human Mandible (2004)
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    Publikationsdatum: 2019-05-10
    Beschreibung: We focus on the role of anisotropic elasticity in the simulation of the load distribution in a human mandible due to a lateral bite on the leftmost premolar. Based on experimental evidence, we adopt ``local''" orthotropy of the elastic properties of the bone tissue. Since the trajectories of anisotropic elasticity are not accessible from Computer Tomographic (CT) data, they will be reconstructed from (i) the organ's geometry and (ii) from coherent structures which can be recognized from the spatial distribution of the CT values. A sensitivity analysis comprising various 3D FE simulations reveals the relevance of elastic anisotropy for the load carrying behavior of a human mandible: Comparison of the load distributions in isotropic and anisotropic simulations indicates that anisotropy seems to ``spare''" the mandible from loading. Moreover, a maximum degree of anisotropy leads to kind of an load minimization of the mandible, expressed by a minimum of different norms of local strain, evaluated throughout the organ. Thus, we may suggest that anisotropy is not only relevant, but also in some sense ``optimal''.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 33
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    Affine conjugate adaptive Newton methods for nonlinear elastomechanics (2004)
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    Publikationsdatum: 2019-05-10
    Beschreibung: The paper extends affine conjugate Newton methods from convex to nonconvex minimization, with particular emphasis on PDE problems originating from compressible hyperelasticity. Based on well-known schemes from finite dimensional nonlinear optimization, three different algorithmic variants are worked out in a function space setting, which permits an adaptive multilevel finite element implementation. These algorithms are tested on two well-known 3D test problems and a real-life example from surgical operation planning.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 34
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    A Geometrical Characterization of the Multidimensional Hausdorff and Dale Polytopes with Applications to Exit Time Problems (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: We present formulae for the corner points of the multidimensional Hausdorff and Dale Polytopes and show how these results can be used to improve linear programming models for computing e.\,g.\ moments of exit distribution of diffusion processes. Specifically, we compute the mean exit time of twodimensional Brownian motion from the unit square and the unit triangle, as well as higher moments of the exit time of time space Brownian motion from a triangle.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 35
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    The Normal Graph Conjecture is true for Circulants (2004)
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    Publikationsdatum: 2014-11-10
    Beschreibung: Normal graphs are defined in terms of cross-intersecting set families: a graph is normal if it admits a clique cover $\cal Q$ and a stable set cover $\cal S$ s.t.~every clique in $\cal Q$ intersects every stable set in $\cal S$. Normal graphs can be considered as closure of perfect graphs by means of co-normal products (Körner 1973) and graph entropy (Czisz\'ar et al. 1990). Perfect graphs have been recently characterized as those graphs without odd holes and odd antiholes as induced subgraphs (Strong Perfect Graph Theorem, Chudnovsky et al. 2002). Körner and de Simone observed that $C_5$, $C_7$, and $\overline C_7$ are minimal not normal and conjectured, as generalization of the Strong Perfect Graph Theorem, that every $C_5$, $C_7$, $\overline C_7$- free graph is normal (Normal Graph Conjecture, Körner and de Simone 1999). We prove this conjecture for a first class of graphs that generalize both odd holes and odd antiholes, the circulants, by characterizing all the normal circulants.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 36
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    One-Point Suspensions and Wreath Products of Polytopes and Spheres (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: It is known that the suspension of a simplicial complex can be realized with only one additional point. Suitable iterations of this construction generate highly symmetric simplicial complexes with a various interesting combinatorial and topological properties. In particular, infinitely many non-PL spheres as well as contactible simplicial complexes with a vertex-transitive group of automorphisms cab be contained in this way.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 37
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    Segmentation of the Liver using a 3D Statistical Shape Model (2004)
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    Publikationsdatum: 2020-03-10
    Beschreibung: This paper presents an automatic approach for segmentation of the liver from computer tomography (CT) images based on a 3D statistical shape model. Segmentation of the liver is an important prerequisite in liver surgery planning. One of the major challenges in building a 3D shape model from a training set of segmented instances of an object is the determination of the correspondence between different surfaces. We propose to use a geometric approach that is based on minimizing the distortion of the correspondence mapping between two different surfaces. For the adaption of the shape model to the image data a profile model based on the grey value appearance of the liver and its surrounding tissues in contrast enhanced CT data was developed. The robustness of this method results from a previous nonlinear diffusion filtering of the image data. Special focus is turned to the quantitative evaluation of the segmentation process. Several different error measures are discussed and implemented in a study involving more than 30 livers.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 38
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    Branching rules revisited (2004)
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    Publikationsdatum: 2021-08-05
    Beschreibung: Mixed integer programs are commonly solved with linear programming based branch-and-bound algorithms. The success of the algorithm strongly depends on the strategy used to select the variable to branch on. We present a new generalization called {\sl reliability branching} of today's state-of-the-art {\sl strong branching} and {\sl pseudocost branching} strategies for linear programming based branch-and-bound algorithms. After reviewing commonly used branching strategies and performing extensive computational studies we compare different parameter settings and show the superiority of our proposed newstrategy.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 39
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    A Bundle Method for Integrated Multi-Depot Vehicle and Duty Scheduling in Public Transit (2004)
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    Publikationsdatum: 2020-03-09
    Beschreibung: This article proposes a Lagrangean relaxation approach to solve integrated duty and vehicle scheduling problems arising in public transport. The approach is based on the proximal bundle method for the solution of concave decomposable functions, which is adapted for the approximate evaluation of the vehicle and duty scheduling components. The primal and dual information generated by the bundle method is used to guide a branch-and-bound type algorithm. Computational results for large-scale real-world integrated vehicle and duty scheduling problems with up to 1,500 timetabled trips are reported. Compared with the results of a classical sequential approach and with reference solutions, integrated scheduling offers remarkable potentials in savings and drivers' satisfaction.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 40
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    Adaptive Finite Element Simulation of the Human Mandible Using a New Physiological Model of the Masticatory Muscles (2004)
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    Publikationsdatum: 2019-05-10
    Beschreibung: Structural mechanics simulation of bony organs is of general medical and biomechanical interest, because of the interdependence of the inner architecture of bone and its functional loading already stated by Wolff in 1892. This work is part of a detailed research project concerning the human mandible. By adaptive finite element techniques, stress/strain profiles occurring in the bony structure under biting were simulated. Estimates of the discretization errors, local grid refinement, and multilevel techniques guarantee the reliability and efficiency of the method. In general, our simulation requires a representation of the organ's geometry, an appropriate material description, and the load case due to teeth, muscle, or joint forces. In this paper, we want to focus on the influence of the masticatory system. Our goal is to capture the physiological situation as far as possible. By means of visualization techniques developed by the group, we are able to extract individual muscle fibres from computed tomography data. By a special algorithm, the fibres are expanded to fanlike (esp. for the musc. temporalis) coherent vector fields similar to the anatomical reality. The activity of the fibres can be adapted according to compartmentalisation of the muscles as measured by electromyological experiments. A refined sensitivity analysis proved remarkable impact of the presented approach on the simulation results.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 41
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    KKT Systems in Operative Planning for Gas Distribution Networks (2004)
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    Publikationsdatum: 2021-02-01
    Beschreibung: Operative planning in gas networks with prescribed binary decisions yields large scale nonlinear programs defined on graphs. We study the structure of the KKT systems arising in interior methods and present a customized direct solution algorithm. Computational results indicate that the algorithm is suitable for optimization in small and medium-sized gas networks.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 42
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    Indexierung von Online-Katalogen: Ein gemeinsames Konzept der ALEPH-Anwender in Berlin (2004)
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    Publikationsdatum: 2021-02-05
    Beschreibung: Der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) verzichtet auf eine einheitliche zentrale Verbunddatenbank zugunsten einer dezentralen, verteilten Struktur. In dieser Architektur erhält die Art der Indexierung der angesprochenen Online-Kataloge eine besondere Bedeutung. So werden sowohl Bibliotheksmitarbeiter als auch Bibliotheksbenutzer immer wieder mit der Recherche in fremden Katalogen konfrontiert, in denen unterschiedliche Indexierungsverfahren realisiert sein können. Ein abgestimmtes Indexierungskonzept verfolgt zwei grundsätzliche Ziele. Einerseits soll durch eine vereinheitlichte Indexierung die Qualität und Zuverlässigkeit der Rechercheergebnisse in der parallelen Suche in mehreren Katalogen über die KOBV-Suchmaschine erhöht werden. Gleichzeitig soll durch eine vereinheitlichte Indexierung die Akzeptanz von Suchen in entfernten Katalogen prinzipiell gesteigert und damit die Bedingungen für die gegenseitige Übernahme von Titeldaten erleichtert werden. Für die Indexierung muss zunächst die Art und der Umfang der im OPAC aufzubauenden Indices festgelegt werden. Aus Sicht des Nutzers entspricht diese Definition den möglichen Sucheinstiegen. Hat man dann entschieden, welche Indexterme aus welchen Feldern in die jeweiligen Indices einfließen sollen, muss bestimmt werden, nach welchen Regeln die Terme behandelt werden. Hier stellt sich insbesondere das Problem der Sonderzeichen wie Bindestriche, Apostrophe und Punkte oder Ziffern in Zeichenketten. Das vorliegende Konzept entstand in Zusammenarbeit der großen Universitätsbibliotheken in Berlin (der Freien Universität, der Humboldt-Universität, der Technischen Universität, der Universität der Künste) mit der KOBV-Verbundzentrale am ZIB.
    Schlagwort(e): ddc:000
    Sprache: Deutsch
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  • 43
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    Integrable quadratic Hamiltonians on so(4) and so(3,1) (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: We investigate a special class of quadratic Hamiltonians on $so(4)$ and $so(3,1)$ and describe Hamiltonians that have additional polynomial integrals. One of the main results is a new integrable case with an integral of sixth degree.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 44
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    Holes, Antiholes and Maximal Cliques in a Railway Model for a Single Track (2004)
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    Publikationsdatum: 2020-11-16
    Beschreibung: We present a graph theoretical model for scheduling trains on a single unidirectional track between two stations. The set of departures of all possible train types at all possible (discrete) points of time is turned into an undirected graph $\Gneu$ by joining two nodes if the corresponding departures are in conflict. This graph $\Gneu$ has no odd antiholes and no $k$-holes for any integer $k\geq 5$. In particular, any finite, node induced subgraph of $\Gneu$ is perfect. For any integer $r\geq 2$ we construct minimal headways for $r$ train types so that the resulting graph $\Gneu$ has $2r$-antiholes and $4$-holes at the same time. Hence, $\Gneu$ is neither a chordal graph nor the complement of a chordal graph, in general. At the end we analyse the maximal cliques in $G$.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 45
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    Robust Process Control by Dynamic Stochastic Programming (2004)
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    Publikationsdatum: 2021-02-01
    Beschreibung: Unnecessarily conservative behavior of standard process control techniques can be avoided by stochastic programming models when the distribution of random disturbances is known. In an earlier study we have investigated such an approach for tank level constraints of a distillation process. Here we address techniques that have accelerated the numerical solution of the large and expensive stochastic programs by a factor of six, and then present a refined optimization model for the same application.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 46
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    The Effect of Hop Limits on Optimal Cost in Survivable Network Design (2004)
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    Publikationsdatum: 2014-02-26
    Beschreibung: We investigate the impact of hop-limited routing paths on the total cost of a telecommunication network. For different survivability settings (dedicated protection, link and path restoration), the optimal network cost without restrictions on the admissible path set is compared to the results obtained with two strategies to impose hop limits on routing paths. In a thorough computational study on optimal solutions for nine real-world based problem instances, we show that hop limits should be avoided if the technology allows it and network cost is a major planning issue. In this case, column generation should be employed to deal with all routing paths. If hop-limits are required, these should be defined for each demand individually and as large as possible.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 47
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    Reoptimization Gaps versus Model Errors in Online-Dispatching of Service Units for ADAC (2004)
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    Publikationsdatum: 2020-11-13
    Beschreibung: Under high load, the automated dispatching of service vehicles for the German Automobile Association (ADAC) must reoptimize a dispatch for 100--150 vehicles and 400 requests in about ten seconds to near optimality. In the presence of service contractors, this can be achieved by the column generation algorithm ZIBDIP. In metropolitan areas, however, service contractors cannot be dispatched automatically because they may decline. The problem: a model without contractors yields larger optimality gaps within ten seconds. One way-out are simplified reoptimization models. These compute a short-term dispatch containing only some of the requests: unknown future requests will influence future service anyway. The simpler the models the better the gaps, but also the larger the model error. What is more significant: reoptimization gap or reoptimization model error? We answer this question in simulations on real-world ADAC data: only the new model ZIBDIP{\footnotesize dummy} can keep up with ZIBDIP.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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    Contraction and Treewidth Lower Bounds (2004)
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    Publikationsdatum: 2020-11-13
    Beschreibung: Edge contraction is shown to be a useful mechanism to improve lower bound heuristics for treewidth. A successful lower bound for treewidth is the degeneracy: the maximum over all subgraphs of the minimum degree. The degeneracy is polynomial time computable. We introduce the notion of contraction degeneracy: the maximum over all minors of the minimum degree. We show that the contraction degeneracy problem is NP-complete, even for bipartite graphs, but for fixed $k$, it is polynomial time decidable if a given graph $G$ has contraction degeneracy at least $k$. Heuristics for computing the contraction degeneracy are proposed and evaluated. It is shown that these can lead in practice to considerable improvements of the lower bound for treewidth, but can perform arbitrarily bad on some examples. A study is also made for the combination of contraction with Lucena's lower bound based on Maximum Cardinality Search (Lucena, 2003). Finally, heuristics for the treewidth are proposed and! evaluated that combine contraction with a treewidth lower bound technique by Clautiaux et al (2003).
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 49
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    Das KOBV-Portal, elektronische Ressourcen in Berlin-Brandenburg: Nachweis, parallele Suche und weiterführende Dienste (2004)
    Details
    Publikationsdatum: 2020-11-13
    Beschreibung: \documentclass[12pt]{article} \usepackage{german} \parindent=0pt \begin{document} Der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) hat in den Jahren 2001 bis 2003 im Rahmen des Entwicklungsprojektes ''KOBV-Informationsportal`` ein regionales Portal aufgebaut, in dem integrierte Informationsdienste fr die regionalen Bibliotheken zur Verfügung gestellt werden. Das ''KOBV-Portal - Digitale Bibliothek Berlin-Brandenburg`` wurde im Dezember 2003 in Betrieb genommen. Das KOBV-Portal bietet in seiner ersten Ausbaustufe den Nachweis über die in den großen Bibliotheken lizenzierten Ressourcen und elektronischen Zeitschriften, zudem die nahtlose Navigation mittels des Reference-Linking-Werkzeuges SFX zu verschiedenen Diensten wie Fernleihe, Subito und freien Volltexten im Internet sowie zu frei zugänglichen elektronischen Zeitschriften. Realisiert wurden ferner die Remote-Authentifizierung, mit der sich ein Nutzer, der online eine Fernleih-Bestellung aufgeben möchte, über das Internet in seiner Heimatbibliothek authentifizieren kann. Des weiteren ist der Zugriff auf lizenzierte Bestände im Campus einer Hochschule mittels IP-Checking möglich. Als weiteren wesentlichen Bestandteil des KOBV-Portals hat die KOBV-Zentrale mit den Bibliotheken einen Workflow für ein Metadata-Sharing abgestimmt und für die Adaption und Normalisierung lokaler Metadaten aus lokalen Bibliothekssystemen und -Portalen den KOBV-Metadaten-Austausch-Parser (KMA-Parser) entwickelt. Damit Bibliotheken, deren Metadaten bislang lediglich in unstrukturierter Form vorliegen, strukturierte Metadaten anlegen, liefern und nachnutzen können, hat die KOBV-Zentrale das mit einer Web-Katalogisierungsschnittstelle ausgestattete ''Metadata-Tool`` entwickelt. Die für das Metadata-Sharing entwickelten Komponenten und Module sollen den Bibliotheken die Mehrfacherfassung ersparen und ihnen die Möglichkeit der wechselseitigen Nachnutzung der Metadaten eröffnen. Der vorliegende Projekt-Abschlussbericht gibt einen Überblick über die während der Projektlaufzeit realisierten Dienste des KOBV-Portals. \end{document}
    Schlagwort(e): ddc:000
    Sprache: Deutsch
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  • 50
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    Wie komme ich optimal zum Ziel? Unterricht über kürzeste-Wege-Algorithmen für Graphen (2004)
    Details
    Publikationsdatum: 2014-02-26
    Beschreibung: Kürzeste Wege tauchen fast überall im Alltag auf. Daher eignet sich dieses Optimierungsproblem gut für den Unterricht. Modellierung und heuristische Vorgehensweisen werden geübt, um schließlich die klassischen kürzesten Wege-Algorithmen selbst zu erfinden. In diesem Artikel werden die Inhalte vorgestellt und konkrete Hinweise zum Unterricht in der Schule gegeben.
    Schlagwort(e): ddc:000
    Sprache: Deutsch
    Materialart: reportzib , doc-type:preprint
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  • 51
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    A Control Reduced Primal Interior Point Method for PDE Constrained Optimization (2004)
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    Publikationsdatum: 2019-01-29
    Beschreibung: A primal interior point method for control constrained optimal control problems with PDE constraints is considered. Pointwise elimination of the control leads to a homotopy in the remaining state and dual variables, which is addressed by a short step pathfollowing method. The algorithm is applied to the continuous, infinite dimensional problem, where discretization is performed only in the innermost loop when solving linear equations. The a priori elimination of the least regular control permits to obtain the required accuracy with comparable coarse meshes. Convergence of the method and discretization errors are studied, and the method is illustrated at two numerical examples.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 52
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    Hierarchical Infrastructure Planning in Networks (2004)
    Details
    Publikationsdatum: 2020-02-11
    Beschreibung: In this article, strategical infrastructure planning problems in the design of large-scale telecommunication networks are discussed based on experiences from three projects with industrial partners: The access network planning of the German Gigabit-Wissenschaftsnetz (G-WiN) for DFN (Verein zur Förderung eines Deutschen Forschungsnetzes e.V.), the mobile network switching center location planning project for E-Plus Mobilfunk, and the fixed network switching center location planning project for TELEKOM AUSTRIA. We introduce a mathematical model for a hierarchical multi-commodity capacitated facility location problem, present adaptions of this basic model to the specific requirements within the different projects and discuss the individual peculiarities and model decisions made. Eventually, we present and discuss computational results of three associated case studies, illustrating '"how we did the job`` with mathematical methods.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 53
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    Degree-Based Treewidth Lower Bounds (2004)
    Details
    Publikationsdatum: 2014-11-10
    Beschreibung: Every lower bound for treewidth can be extended by taking the maximum of the lower bound over all subgraphs or minors. This extension is shown to be a very vital idea for improving treewidth lower bounds. In this paper, we investigate a total of nine graph parameters, providing lower bounds for treewidth. The parameters have in common that they all are the vertex-degree of some vertex in a subgra ph or minor of the input graph. We show relations between these graph parameters and study their computational complexity. To allow a practical comparison of the bounds, we developed heuristic algorithms for those parameters that are NP-hard to compute. Computational experiments show that combining the treewidth lower bounds with minors can considerably improve the lower bounds.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 54
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    The convergence of an interior point method for an elliptic control problem with mixed control-state constraints (2004)
    Details
    Publikationsdatum: 2019-01-29
    Beschreibung: The paper addresses primal interior point method for state constrained PDE optimal control problems. By a Lavrentiev regularization, the state constraint is transformed to a mixed control-state constraint with bounded Lagrange multiplier. Existence and convergence of the central path are established, and linear convergence of a short-step pathfollowing method is shown. The behaviour of the regularizations are demonstrated by numerical examples.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 55
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    Homogenization for a Nonlocal Coupling Model (2004)
    Details
    Publikationsdatum: 2014-02-26
    Beschreibung: In [7,8,12] homogenization techniques are applied to derive an anisotropic variant of the bio-heat transfer equation as asymptotic result of boundary value problems providing a microscopic description for microvascular tissue. In view of a future application on treatment planning in hyperthermia, we investigate here the homogenization limit for a coupling model, which takes additionally into account the influence of convective heat transfer in medium size blood vessels. This leads to second order elliptic boundary value problems with nonlocal boundary conditions on parts of the boundary. Moreover, we present asymptotic estimates for first order correctors.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 56
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    Polynomial Inequalities Representing Polyhedra (2004)
    Details
    Publikationsdatum: 2014-02-26
    Beschreibung: Our main result is that every $n$-dimensional polytope can be described by at most $2n-1$ polynomial inequalities and, moreover, these polynomials can explicitly be constructed. For an $n$-dimensional pointed polyhedral cone we prove the bound $2n-2$ and for arbitrary polyhedra we get a constructible representation by $2n$ polynomial inequalities.
    Schlagwort(e): ddc:000
    Sprache: Englisch
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  • 57
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    Das KOBV-Metadaten-Schema im KOBV-Portal (2004)
    Details
    Publikationsdatum: 2023-10-05
    Beschreibung: Das KOBV-Metadaten-Schema ist von der KOBV-Zentrale entwickelt worden, um Ressourcen im Sinn von Informationskollektionen wie Datenbanken oder Fachportale zu beschreiben. Es ist ein wichtiger Bestandteil des KOBV-Portals, das die in der Region verf"ugbaren Ressourcen nachweist. Das KOBV-Metadaten-Schema dient den Bibliotheken zur Handreichung, um dem KOBV-Portal die Ressourcen mit den standardisierten und individuellen Angaben zu melden, so dass die Ressourcebeschreibungen einem austauschbaren Format entsprechen. Auf diese Weise k"onnen Ressourcebeschreibungen von anderen Bibliotheken mitgenutzt werden und ein Metadata-Sharing in der Region Berlin-Brandenburg praktiziert werden, um in diesem Bereich doppelte Arbeiten zu sparen.
    Schlagwort(e): ddc:000
    Sprache: Deutsch
    Materialart: reportzib , doc-type:preprint
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  • 58
    Digitale Medien
    Digitale Medien
    Early secretory activity in the hypothalamic nuclei and neurohypophysis in the rat; determined by selective staining (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 118 (1966), S. 549-563 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Visualization of stainable material in the neural lobe of the rat provided the most reliable index of the age at which secretory activity can first be recognized, though preceded by both hypothalamic synthesis and axonal transportation. A problem of interpretation was encountered in the neural lobes of fetal and infant animals, due to different staining responses obtained during this age period, to the two methods of staining employed; chrome alum hematoxylin-phloxin and aldehyde fuchsin after oxidation by either acidified potassium permanganate or performic acid. With aldehyde fuchsin the material of the neural lobe is stainable selectively from the eighteenth day of fetal life to adulthood. With hematoxylin phloxine the first staining response also occurred in the posterior lobe but much later, at the end of the first postnatal week.The staining situation in the pars neuralis has its counterpart in the differentiating hypothalamic nuclei; complicated by the differentiation of the supraoptic nuclei some days in advance of the paraventricular nuclei. After aldehyde fuchsin staining, evidences of neurosecretory activity were present in the perikarya of the supraoptic nuclei at birth, but mature neurons were rarely seen in the paraventricularis until at least 24 hours later. Nuclei of fetal hypothalami were not studied, but the demonstration of stainable material in the fetal neural lobes constitutes circumstantial evidence of functional competence of some neurons of either one or both types of nucleus, most likely the supraoptic.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051180408
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  • 59
    Digitale Medien
    Digitale Medien
    Erythrocyte replacement at metamorphosis in the frog, rana pipiensSupported by PHS grant HD00725-05 to A. G. Jacobson. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 1-5 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Small crenulated erythrocytes appear in the circulation of Rana pipiens during metamorphosis, increases in number as metamorphosis proceeds and gradually lose their wrinkled appearance. At the end of metamorphosis the entire red cell population has been replaced by these new cells. Thyroxine induces the premature appearance of these new cells in young tadpoles.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190102
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  • 60
    Digitale Medien
    Digitale Medien
    Histological changes in the epidermis of the tokay (Gekko gecko) during the sloughing cycle (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 39-50 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190105
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  • 61
    Digitale Medien
    Digitale Medien
    The gastric argentaffin cell population of the ratThe work described herein fulfilled in part the requirements for the doctoral dissertation at the University of Southern California. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 81-87 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The distribution and morphology of the argentaffin cell population within the stomach of the albino rat has been investigated histologically. The argentaffin cell's situation is restricted to and evenly distributed over the antrum, lying usually in the basal third of the mucosa among mucous cells. A band of mucosa, less than a millimeter wide, containing argentaffin cells, extends from the antrum and encircles the stomach just caudal to the forestomach. The argentaffin cell population is found in less than three-tenths of the total stomach by weight, a point for consideration in serotonin assay.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190107
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  • 62
    Digitale Medien
    Digitale Medien
    Masthead (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190201
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  • 63
    Digitale Medien
    Digitale Medien
    A study of a hereditary cataract in the mouseSupported in part by O'Brine Medical and Research Fund. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 89-100 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: This report presents a study of cataracts seen in a random-bred strain of Swiss mice with Balb/c mice used as a control group. The embryonic development, and histological and slit lamp observations of the lenses in the two groups of animals are contrasted.The cataract is dominant in its inheritance (Tissot, '62). It appears either unilaterally or bilaterally as a dense white opacity in the lens substance. The earliest sign of abnormal formation occurs at 14 days of embryonic development. This is associated with a defect in the primary lens fibers formation. Progressive degeneration of these fibers occurs until they are reduced to a mass of cellular debris seen at the last day of gestation. The secondary fibers are also laid down in an abnormal manner. The normal lamellar arrangement of the secondary fibers is not seen in cataractous lenses.The abnormal lens fiber development leads to progressive vacuolization.The mature cataract seen in the adult is filled with many vacuoles, the largest ones occurring at the equatorial region. The nuclear region consists of a clumpy eosinophilic mass with scattered calcified areas. The rate of growth of the secondary fibers is different from that of the normal group. Most of the mature cataracts in the adult contain a vascularized epithelium.There are three possible areas of primary involvement which may lead to the development of the cataract. This are: (1) A defect in the development of the primary lens fibers; (2) A defect in the development of the secondary lens fibers; (3) An abnormal lens epithelium which may interfere with nutrition of the lens and thus initiate cataract formation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190108
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  • 64
    Digitale Medien
    Digitale Medien
    Microanatomy of the heart and associated structures of two scorpions, Centruroides sculpturatus ewing and Uroctonus mordax thorellPart of a thesis submitted in partial fulfillment for the M.S. degree in entomology at the University of California, Berkeley. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 161-180 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Spiroid orientation of the circumferential heart wall muscles is described for Centruroides sculpturatus Ewing. This muscle arrangement accounts for differences in ostial position when the heart of this species is compared to that of Uroctonus mordax Thorell. Other differences, such as number of lateral arteries present, cannot be explained on the basis of circumferential muscle orientation.The histology of the heart and associated vessels, but not the supraneural vessel, was found to be similar in both species. The lateral, posterior, communicating and sternal arteries all possess a muscularis composed of irregularly spaced, apparently branched, striated muscle fibers. External to this is a covering of connective tissue. The lumina of these arteries, the aorta, and the supraneural vessel are lined with a homogeneous, PAS-positive membrane. This membrane is also seen in blood vessels which penetrate the nervous system. It was not observed in vessels accompanying major nerves.Findings are compared to those of other authors. Differences in the structure of the hearts of these two species are discussed in relation to the microanatomy of other arachnid hearts.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190205
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  • 65
    Digitale Medien
    Digitale Medien
    Tooth replacement in the frog Rana temporaria (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 233-240 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The development and replacement of teeth in the frog Rana temporaria is analyzed by dividing the life cycle of the tooth into a number of stages. These stages are identified by the examination of alizarin whole mounts. The dentition in this species is fairly complete and the percentage of functional loci is approximately 74. The teeth in alternate loci are usually at about the same stage in development. The low percentage of non-functional loci is accounted for by the retention of functional teeth over a large fraction of the total life cycle time and the relatively rapid ankylosis of replacement teeth. It is suggested that tooth replacement is essentially a process which involves teeth in alternate loci and that the replacement waves (which connect alternate loci) run parallel to the longitudinal axis of the jaw and are of infinite length. This basic pattern is obscured by many breaks which occur in the replacement waves. The presence of such breaks may be accounted for by variations in the time intervals between the successive stimuli which initiate the Zahnreihen, or simply by the acceleration or deceleration of the development of teeth in one or more loci.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190209
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  • 66
    Digitale Medien
    Digitale Medien
    The development of the musculature of the hindlimb in the frog, Rana pipiensThis investigation was supported by Research grant G18668 from the National Science Foundation to the author. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 241-258 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The major features of the morphogenesis of the muscles of the hindlimb, exclusive of the foot, are described and illustrated for the frog, Rana pipiens The description is carried through the stage XII larva, in which stage most of the muscles of the adult limb are present in essentially the definitive condition. As is true of other vertebrates which have been studied, the muscles of the hindlimb develop from two major premuscular masses. One of these lies along the dorsolateral margin of the limb and the other along the ventro-medial margin. Each of the two masses is subsequently divided into smaller and smaller subdivisions as the different muscle groups and the individual muscles are differentiated. In general, the more proximally located muscles differentiate before those which are located more distally and those of the dorso-lateral mass before those of the ventro-medial mass.The following muscles of the thigh, shank and tarsus develop from the dorsolateral mass: ileo-fibularis, glutaeus magnus, cruralis, ileo-femoralis, iliacus externus, iliacus internus, tensor fasciae latae, pectineus, adductor longus, peroneus, tibialis anticus brevis, tibialis anticus longus, extensor cruris brevis, tarsalis anticus, extensor digitorum communis longus and abductor brevis dorsalis. The following develop from the ventro-medial mass: compressor cloacae, circumflexor arteriae, pyriformis, semimembranosus, gemellus, gracilis major, gracilis minor, semitendinosus, adductor magnus, obturator internus, obturator externus, quadratus femoris, sartorius, plantaris longus, tibialis posticus, tarsalis posticus, plantaris profundus, intertarsalis and flexor digitorum brevis superficialis.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190210
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  • 67
    Digitale Medien
    Digitale Medien
    Histochemistry of the chick esophagus and tracheaThis investigation was supported by National Institute of Arthritis and Metabolic Diseases research grant AM-05429. II. Enzymes, nucleic acids, proteins, carbohydrates, and fats (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 327-339 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Tissues of White Leghorn embryos of stages 17-45 and chicks of one day, two days, and three weeks of age were frozen, sectioned in a cryostat and, where appropriate, were fixed in cold calcium formol. Acid phosphatase, non-specific esterase, adenosine triphosphatase, 5-nucleotidase, non-specific glycerophosphatase, nucleotidediphosphatase, and glucose-6-phosphatase were localized in these tissues. Ribonucleic acid, acid mucopolysaccharides, triglycerides, and neutral fats were localized in tissues fixed with FAA and embedded in paraffin.Positive acid phosphatase reactions were obtained in the epithelium of the trachea and esophagus at all stages of development. 5-nucleotidase was found in the muscularis mucosae of the esophagus at all stages. Non-specific esterase appeared with histodifferentiation of the esophageal epithelium. Ribonucleic acid was localized in the basal regions of the epithelium.Mucous glands of the esophagus are rich in ribonucleic acid and acid phosphatase at all stages of development. With histodifferentiation and the onset of secretion of sulfated acid mucopolysaccharides, the glands and their ducts become highly reactive for adenosine triphosphatase and nucleotide-diphosphatase, indicating a role of these enzymes in secretion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190305
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  • 68
    Digitale Medien
    Digitale Medien
    Variation in the circumtesticular leydig cell tunic of teiid lizards (Cnemidophorus and Ameiva) (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 277-281 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Testicular structure in bisexual teiid lizards (Cnemidophorus and Ameiva) is apparently unique among vertebrates in having a circumtesticular subtunic band of Leydig (interstitial) cells, that varies in species of Cnemidophorus from 1.2 to 42.1 cells in thickness (transverse cross-section), between the outer tunic (tunica albuginea) and the seminiferous tubules. The regression on body size, ontogenetic change, seasonal periodicity, and other aspects of structure and function of this subtunic Leydig cell structure are discussed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190302
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  • 69
    Digitale Medien
    Digitale Medien
    The origin and early differentiation of the egg chamber of Drosophila melanogasterThis research was supported by the U. S. Public Health Service grants 2-F2-CA-18,847 and GM 9694, the National Science Foundation grant GB 4891, and the American Cancer Society grant E408. The authors wish to express their appreciation to Mrs. Elizabeth T. Stump for her conscientious assistance, and to Mr. E. John Pfiffner for preparation of the inked drawings. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 283-303 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The egg chamber of Drosophila melanogaster consists of 16 interconnected cells surrounded by a monolayer of follicle cells. Each 16 cell cluster (from which the oocyte and 15 nurse cells differentiate) arises within the germarial region of an ovariole. To study the ultrastructure of the early stages in the formation and differentiation of egg chambers, a three dimensional reconstruction was made from serial thin sections through a germarium from a 24-hour old, virgin female. The germarium was found to be subdivided into three regions: (1) The mitotically active area where clusters of 16 cells originate from a series of cystocyte divisions, (2) the region where these cells interact with mesodermal cells, and (3) the region where the germarial cyst is transformed into the first egg chamber in the vitellarium. Since cystocytes were found to decrease in size with each division, the possibility exists that cell size may determine when the divisions cease. Models are presented which mimic with varying degrees of success the developmental changes the germarial cells undergo with time. Hypothesis are developed to explain why stem line oogonia are restricted to the anterior portion of the germarium, why mesodermal cells first interact with cystocytes in region 2, and why the oocyte is oriented posteriorly. The nuclear differentiations of the component cells of the chamber are described and correlated with observed differences in radiosensitivity. Symbionts were observed in the germaria of several strains of Drosophila, and the bearing of these findings upon nutritional studies is discussed.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190303
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  • 70
    Digitale Medien
    Digitale Medien
    The effect of molting upon the vibration receptor of the spider (Achaearanea tepidariorum)Supported in part by contract 1866(46) and 3225(00) between the Office of Naval Research and Harvard University; by a United States Public Health Service Research grant GM 10422 from the Division of General Medical Science, and by a PHS Career Development Award NB-K3-3738 from the Division of Neurological Diseases and Blindness. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 383-392 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The physiology and fine structure of the vibration receptor of the spider (Achaearanea tepidariorum) was studied throughout the process of molting. The physiological studies showed that there is no dramatic change in the receptor's vibration sensitivity as the time of ecdysis approaches. Only a gradual loss of sensitivity can be detected on a statistical basis using large numbers of spiders. The fine structural studies suggest that the connection between the sensory neurone and the receptor within the old cuticle remains intact up to the time that the cuticle is shed.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190308
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  • 71
    Digitale Medien
    Digitale Medien
    Embryonic development of the ciliary arteries of the rabbit from inception through the emergence of the circulus arteriosus iridisSupported by research grant HE-04838.05sl, National Institutes of Health, U. S. Public Health Service. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 393-416 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Since the rabbit's eye more nearly resembles the human eye than any other mammal used in experimental investigations, a detailed study of its ciliary arteries has been made. A closely timed series of embryos injected through the living umbilical vein and rendered transparent show, in thick sections, silhouetted vessels in perspective. Heretofore the ciliary arteries have been studied from their first identification until they have reached the primitive choriocapillaris, but no farther. This study shows their complete history including their relation to the circulus arteriosus iridis major and to the pupillary membrane. Our special concern has been ferreting out the mode of migration of the components of the definitive arteries. New findings include: (1) an arteriovenous plexus which mediates the transference from vessels anastomotic with it to other such vessels; (2) functionally different segments of the primitive ciliary arteries; (3) different arterial and venous plexuses which play roles in embryonic development; (4) discovery of the realignment of the choriocapillaris into vertical vessel meshes with transverse anastomoses between them, each of which have different fates; (5) the mode of development of the circulus arteriosus iridis major; (6) a crown of venous vessels looping around the iris margin; and (7) a special arterial supply for the ciliary processes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190402
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  • 72
    Digitale Medien
    Digitale Medien
    A comparative investigation of neuroglia in representative vertebrates: A silver carbonate studyThis investigation was supported by Public Health Service Research grant 1-F1-GM-22,665-01 (Pre-Doctoral fellowship) from the National Institutes of Health and General Research Support Grant 320002 of the United States Public Health Service. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 435-465 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The phylogenetic development of neuroglia (astrocytes, oligodendrocytes) was investigated in homologous cortical and subcortical forebrain regions of selected vertebrates. Microglia were not considered in the current study.Four to seven brains from each species were used. Scharenberg's modification for astroglia of del Rio Hortega's silver carbonate technique was used. The analysis of neuroglia cells was based on (1) the characteristic cellular morphology found in each species, (2) a comparison of the selected regions in each animal, (3) the interrelationships of astrocytes and their relations to neurons, blood vessels, and oligodendrocytes.The predominant type of neuroglia found in the fish, frog, and lizard was the ependymal cell; however, non-ependymal glial cells were also present. The bird represented a transitional phylogenetic stage from a predominance of ependymal glial to a predominance of non-ependymal glia. A progressive increase in the morphological relationships of glial cell bodies and processes to neurons was found with ascension of the phylogenetic scale from fish through primate.Interrelations were observed between adjacent astrocytic processes and cell bodies, and between astrocytes and oligodendrocytes. The processes of adjacent glial cells also appeared to show an increase in thickness at the point of approximation. A variety of astrocytes were observed ranging from small, round-oval shaped cells to large polygonal or stellate forms. Variations in the number of astrocytic processes, their thickness, and degree of secondary branching were described, and their possible functional significance was discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190405
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  • 73
    Digitale Medien
    Digitale Medien
    A histological and ultrastructural study of germinal differentiation of interstitial cells arising from gland cells in Hydra viridis (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 120 (1966), S. 1-8 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Gland cells of the gastrodermis of Hydra when isolated from the epidermis are capable of dedifferentiating into interstitial cells. Under proper environmental conditions these interstitial cells are capable of undergoing meiotic divisions and forming normal gametes. This dedifferentiation and redifferentiation sequence has been studied at the level of the light and electron microscope. It is concluded that in Hydra there is no specific germinal cell line determined during embryogeny, and that a somatic cell under proper environmental conditions can be induced to undergo meiosis.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051200102
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  • 74
    Digitale Medien
    Digitale Medien
    Fine structural organization of the rectum in the blowfly, Calliphora erythrocephala (Meig.) with special reference to connective tissue, tracheae and neurosecretory innervation in the rectal papillae (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 120 (1966), S. 23-81 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The rectal epithelium of Calliphora is made up of three quite distinct cell types: rectal, cortical and junctional cells.The thin wall of the rectal pouch is made up of rectal cells which are relatively simple and unspecialized; their general structure does not suggest any direct participation in ion transport.A function of ion and water transport can probably be ascribed to the cortical cells, which are arranged in the form of four cones which project into the rectal lumen. The cavity of each cone is filled up with tracheae, nerve and neurosecretory terminals, and connective tissue to form medulla. The medulla and cortex are separated from each other by deeply staining bridges or trabeculae to form an infundibular space. The most conspicuous feature of the cortex is the presence of an extensive intercellular sinus formed by complex infoldings of the lateral plasma-membranes. It is postulated that fluid, which is absorbed from the rectal lumen, is transported into the intercellular sinus and finally reaches the haemolymph via the infundibular space. The actual site of ion transport is probably the stacks of lateral plasma-membrane which are closely associated with mitochondria.The junctional cells, which are packed with microtubules, form a collar around the base of the papillae at the point of their insertion into the rectal wall.It is suggested that the neurosecretory terminals present in the medulla might release a hormone which controls rate of ion and water reabsorption by the papillae cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051200104
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  • 75
    Digitale Medien
    Digitale Medien
    Sense organs on the antennal flagellum of a walkingstick Carausius morosus Brünner (Phasmida)This work was supported in part by a grant from the National Science Foundation GB-4553. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 120 (1966), S. 189-201 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The long, filamentous antennal flagellum of Carausius morosus has on it three types of sense organs (1) tactile hairs, (2) thick-walled chemoreceptors and (3) thin-walled chemoreceptors. Tactile hairs and thick-walled chemoreceptors are present on all of the 40 or more flagellar subsegments while thin-walled chemoreceptors are limited to about one-third of them. Thin-walled chemoreceptors are present on subsegments nine and ten, one of the subsegments between 15 and 20 and from approximately the thirtieth subsegment to the distal end of the antenna. A description of each of these sense organs is given. No coeloconic or campaniform sense organs were found.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051200205
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  • 76
    Digitale Medien
    Digitale Medien
    Choroid plexus and paraphysis in lower vertebratesSupported in part by Public Health Service grant NB-5383 from the National Institute of Neurological Diseases and Blindness. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 120 (1966), S. 157-187 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Cytoarchitecture of the choroid plexus of the third ventricle and the paraphysis was investigated in some lower vertebrates to compare the histologic characteristics of these organs. Both epithelia are similar in appearance in the same class. Minor microscopic variations exist in the different classes of vertebrates, but do not provide a fundamental distinction between the two organs. The epithelia, moreover, have similar staining properties, contain mucicarmine- and PAS-reactive materials, and are derived from a common neuroepithelium. Tubules are identified in the choroid plexus and in the paraphysis; all are similarly formed by simple folding of epithelium on the surface into the stroma. The paraphyses in all vertebrates studied contain villi similar to those seen in the choroid plexus. Cilia are identified in both choroidal and paraphyseal epithelia, and are not an indication of degree of epithelial differentiation. Many types of epithelium are noted in both organs during histologic differentiation as well as in the mature stage. Functionally, the choroid plexus is active in both secretion and absorption. Accumulation of particulate material within the epithelial cytoplasm may indicate phagocytic as well as absorptive activity of cells. Based on a common neuroepithelial origin and similar histochemical properties, we conclude that the paraphysis is a modified choroid plexus. The velum transversum is an arbitrary boundary between diencephalon and telencephalon, and is itself formed of choroid plexus. The medial telencephalic ventricle is the rostral portion of the third ventricle. All neuroepithelial infoldings at the rostral end of the diencephalic roof including the velum transversum are intraventricular choroid plexuses; the neuroepithelial outpouchings in this region are the extraventricular choroid plexuses (paraphysis) of the diencephalon.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051200204
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  • 77
    Digitale Medien
    Digitale Medien
    Placentation and associated aspects of gestation in the bonnethead shark, Sphyrna tiburoThis work was supported by a National Science Foundation grant and by Contract Nonr-401(33) NR 104-71 between the Office of Naval Research, Department of the Navy, and Cornell University. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 120 (1966), S. 219-231 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The left ovary of the bonnethead shark, Sphyrna tiburo, is rudimentary, and the right ovary supplies both oviducts which share a common ostium situated in the falciform ligament. Preceding ovulation the nidamental gland of each oviduct hypertrophies and the caudal two-thirds of each oviduct is modified to form a uterus. In the Florida-Caribbean area Sphyrna tiburo probably mates in March and 3-7 eggs are fertilized in the vicinity of the nidamental gland of each oviduct.The developing embryo is nourished during the first 3-4 months of gestation by yolk stored in its extensive yolk sac. Approximately three and one-half months after fertilization, the distal portion of the yolk sac becomes convoluted and interdigitates with deep folds in the uterine wall to form a yolk-sac placenta. As the placenta develops, the maternal uterine epithelium is reduced from columnar cells to squamous cells, and the foetal yolk-sac epithelium is reduced from columnar and cuboidal cells to squamous cells. Exchange between the maternal and foetal blood systems takes place through maternal endothelium, reduced maternal epithelium, egg-case membrane, reduced foetal epithelium, and foetal endothelium.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051200302
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  • 78
    Digitale Medien
    Digitale Medien
    Masthead (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 120 (1966) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051200401
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  • 79
    Digitale Medien
    Digitale Medien
    Histochemical observations on mucin secretion by subsurface epithelial structures in the canine ovary (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 120 (1966), S. 347-358 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Histochemical methods for mucins were applied to the ovaries of 23 dogs.Solid and hollow groups and cords of epithelial cells (subsurface epithelial structures, SES) in the outer part of the cortex regularly showed evidence of mucin secretion. Intracytoplasmic, sialic acid-containing, acid mucin secretion droplets were seen in solid and hollow SES, and secretion was present in both closed lumina and those opening onto the surface.Intracytoplasmic droplets in the cells of SES were distinctive, and similar droplets were not found in the cells of any other ovarian epithelial component. The secretion of SES was not shown to possess distinctive histochemical features.Mucin production was also observed in follicles, corpora lutea and rete tubules.The significance of ingrowth from the ovarian surface epithelium in adult life, and of secretory activity by the cells of SES, are discussed.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051200403
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  • 80
    Digitale Medien
    Digitale Medien
    Observations on the ultimobranchial gland in small wild and laboratory mammals, with special reference to the histochemical localization of polysaccharidesThis particular phase of a study that has been in progress for several years was begun in the summer of 1963 during the author's tenure as a Resident Research Associate in the Division of Biological and Medical Research, Argonne National Laboratory, Argonne, Illinois. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 120 (1966), S. 425-441 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: This is the last of a series of observations involved in a comparative histological study of the ultimobranchial body in vertebrates. Complete serial longitudinal or transverse paraffin sections were made of formol alcohol, Bouin's, and formalin-fixed ultimobranchial and thyroid tissues that had been removed from adult specimens of the cat, cotton rat, ground squirrel, Guinea pig, kangaroo rat, bushytailed wood rat, rabbit, and raccoon. The alcian blue-PAS, aldehyde fuchsin-alcian blue, mucicarmine, alcian blue-safranin, Best's carmine, and toluidine blue staining procedures show that the glandular mammalian ultimobranchial tissue is capable of producing considerable amounts of various mucosubstances, particularly the acid mucopolysaccharides, and other carbohydrate-containing materials. The carbohydrate moiety has been histochemically identified as mucopolysaccharides possessing acidic groups, those having both carboxyl and ester sulfate groups; and as glycogen, muco-and glycoproteins and other carbohydrate-protein complexes. The differences in the intensity and localization of a given staining reaction reflect not only individual and species variations but also significant differences in the position of the ultimobranchial tissue in relation to the thyroid gland. An accessory thyroid lobule found near parathyroid IV and thymus IV in a bushy-tailed wood rat may represent a cystic manifestation of the ultimobranchial body because its follicles varied greatly in size and were lined by a thick stratified squamous epithelium. The possible hormonal mechanisms (TSH, thyroxine) involved in the regulation of ultimobranchial activity are discussed in relation to the gland's production, storage, and release of mucopolysaccharides and other secretory substances.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051200407
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  • 81
    Digitale Medien
    Digitale Medien
    The structure and maturation of the spermatozoa of Sciara coprophila (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 118 (1966), S. 11-41 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The axial filament of Sciara coprophila does not conform to the usual 9 + 2 filament pattern but consists, rather, of as many as 76 pairs of filaments which decrease in number from the anterior to the posterior region of the sperm. It is first seen at the base of the head in the shape of an indented oval. The axial filament varies in configuration along the remaining length of the sperm as one whorl or two connected whorls of filament pairs.The other structures of the sperm revealed by the light and electron microscopes are a homogeneous, dense, spear-shaped nucleus, a row of spherical dense bodies in the middle piece enclosed by the axial filament and of unknown nature and function and a single mitochondrial derivative.The mitochondrial nebenkern derivative consists of a large electron transparent region bordered by cristae and a smaller paracrystalline region located adjacent to the axial filament. The derivative arises as paracrystalline material in a medial nuclear indentation. The electron transparent material is first seen at the anterior end of the middle piece.Unlike other known insect sperm, but reminiscent of sperm capacitation in mammals, sperm maturation is completed in the spermathecae of Sciara 7 to 9 hours after insemination. It consists of the acquisition of sperm motility and elimination of the electron transparent region of the mitochondrial nebenkern derivative. The electron microscope reveals in mature sperm that the axial filament doublets have changed configuration and consist of a single whorl which encloses the paracrystalline rod. The process by which the major portion of the nebenkern derivative is eliminated occurs in four identifiable stages. Since sperm maturation does not appear to be intrinsically controlled, factors in the spermathecal fluid may play a role in its completion.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051180103
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  • 82
    Digitale Medien
    Digitale Medien
    Endometrial vascularity during pseudopregnancy in the rabbitThis investigation was supported in part by USPHS Research grant HD 00585-03, National Institute of Child Health and Human Development. Scientific Paper no. 2377, Washington Agricultural Experimental Stations, Pullman. Project 1698. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 118 (1966), S. 43-56 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The vascular architecture in the rabbit uterus was studied during pseudopregnancy. Uteri at 2, 3, 4, 6, 7, 8, 9, 11, 13, 16, 17, 18, 20, 24 and 28 days after sterile mating were subjected to one of four techniques: neoprene latex casts, transparent sections, frozen sections, and histological sections. Measurements were made microscopically of the thickness of myometrium and of the subepithelial capillary plexus in the different mucosal folds. In the estrous rabbit, the circular arteries in the uterine muscular layer give off arterioles which pass upwards, with a few branchings through the endometrium to the uterine lumen. These arterioles reach the surface of the mucosal folds and break up into the subepithelial capillary plexus. This plexus is connected to the tips of the venules which run down through the endometrium to the endometrial vascular plexus at the base of the endometrium: some of the venules connect with the circular venous vessels in the muscular layer. With advanced stages of pseudopregnancy, the capillaries among the glands become stretched and elongated. Maximal branching of the folds occurs at 4 to 9 days of pseudopregnancy. The “branching activity” was consistently higher in the placental than in the periplacental or in the obplacental folds. Such changes reached a maximum at 6 to 7 days p.c., after which the capillaries became gradually shorter and tortuous. The development of arterioles in the mucosa was marked at 3 to 6 days p.c. The thickness of the plexus in the periplacental fold and in the obplacental fold as a percentage of the thickness in the placental fold was highly correlated with the stage of pseudopregnancy. At 9 to 11 days p.c., these ratios reached a minimum of 70 to 80%.
    Zusätzliches Material: 23 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051180104
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  • 83
    Digitale Medien
    Digitale Medien
    Development of the gonads in Channa punctatus bloch (osteichthyes: Channidae) (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 467-475 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The history of the germ cells is traced from the time of hatching. The germ cells are larger in size and have faintly staining cytoplasm, clear cell outline and a distinct nucleus. They migrate by ameboid movement to reach the genital ridge and aggregate to lie against the gonadal epithelium prior to the formation of gonads. The germ cells are distributed along the gonad primordia.The period of sex differentiation occurs between the 5.4 mm to 12 mm stage. The testis formation is recognized by the presence of germ cell nests and the sperm duct cord. The formation of the ovary is noted by the enlargement of the germ cells of uniform size and the development of the ovarian cavity.The ovaries are described in four stages ranging from 21 mm to 135 mm fish. At 21 mm stage the ovarian cavity is continuous but is obliterated at 35 mm stage due to the projection of the ovigerous lamellae. The common opening for both the ovaries develops at 35 mm stage. The testes are described in four stages ranging from 23 mm to 135 mm fish. They differentiate more slowly and the first maturation division is seen at 90 mm stage.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190406
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  • 84
    Digitale Medien
    Digitale Medien
    The structure and function of the gill tufts in larval Amphipterygidae (Odonata: Zygoptera) (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 120 (1966), S. 9-21 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Larvae of the subfamily Amphipteryginae (Odonata) bear a tuft of tracheal gills on either side of the anus. The two tufts are derived from the laminae sub-anales, and are protected by the non-respiratory epiproct and paraprocts, and by plates derived from the cerci, lamina supra-analis or the lamina sub-analis itself. Each is approximately 1 mm long in mature larvae and comprises a series of repeatedly branching filaments, the terminal twigs of which are 5 to 10 μ in diameter. The total surface area of the tufts is approximately 5.0 mm2 in mature larvae of Devadatta, and more in the larvae of Pentaphlebia and Rimanella. Each tuft is connected by a large trachea to the longitudinal tracheal trunk. This large trachea divides many times, eventually forming a dense palisade of tracheoles in the epidermis of the filaments, immediately beneath the thin investing cuticle.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051200103
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  • 85
    Digitale Medien
    Digitale Medien
    Studies on the embryogenesis of Aulocara elliotti (Thomas) (Orthoptera, Acrididae).This investigation was supported by Public Health Service Research grant EF-00331-02 from the National Institutes of Health.This paper is part of a dissertation submitted in partial fulfillment for the degree of Doctor of Philosophy in Entomology from the Department of Zoology and Entomology, Montana State University, Bozeman, Montana.Montana Agricultural Experiment Station, Journal Paper no. 779. I. External morphogenesis (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 120 (1966), S. 83-113 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The growth and morphogenesis of embryos of Aulocara elliotti (Thomas) at constant temperature are described in terms of 27 discrete morphological stages with four stages designating blastokinesis. The developmental variability of two series of embryos reared from a single wild population in two different years is compared. A bibliography to studies on other embryos of the Acrididae is included.
    Zusätzliches Material: 7 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051200105
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  • 86
    Digitale Medien
    Digitale Medien
    Cardiac glycogen depletion in Amphiuma means during induced anoxia (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 120 (1966), S. 391-396 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Giant salamanders, Amphiuma means, measuring 240 to 280 mm from snout to vent, tolerate induced anoxia for six hours. Most of the cardiac glycogen (beta units) is depleted within the first hour of anoxia but a few scattered units remain after six hours. The suggestion that cardiac glycogen is a stand-by energy source which enhances the energy available to the heart during anoxic strain is reasonable. Beta units are stored in the heart as opposed to the larger alpha units in the liver. The smaller beta units are probably more easily metabolized than the larger alpha units due to their greater surface area per volume ratio and dispersal around the numerous cardiac mitochondria.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051200405
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  • 87
    Digitale Medien
    Digitale Medien
    A Comparative electron microscopic study of cytoplasmic microtubules and axial unit tubules in a spermatozoon and a protozoan (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 120 (1966), S. 397-423 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Cytoplasmic microtubules and axial unit tubules were studied in both sectioned and negatively-stained material. Walls of microtubules of frog lung-fluke (Haematoloechus medioplexus) spermatozoa have a helical substructure, while those of the flagellate, Trypanosoma lewisi, are composed of ten longitudinally-oriented filaments. Cross-bridges occur between some filaments of trypanosome microtubules. Doublet tubules of axial units in both cell types are structurally similar to the trypanosome microtubules, which may indicate similarity of function. Microtubules of fluke spermatozoa appear to be somewhat rigid, are resistant to sonication, and are considered to be mainly supportive. Circular profiles of wall subunits are seen in transverse sections of microtubules of both cell types and in doublet tubules of the trypanosome. Comparisons are made between sectioned and negatively-stained material; while negative-staining better reveals the fundamental substructure of microtubular elements, some distortion appears to occur. In connection with this research, a brief preliminary article demonstrated the presence of subunits in the walls of cytoplasmic microtubules of fluke spermatozoa (Burton, '66). Also, it was shown that the wall of these tubular elements possesses a helical structure, and a diagrammatic representation of the wall structure was set forth.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051200406
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  • 88
    Digitale Medien
    Digitale Medien
    Masthead (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190101
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  • 89
    Digitale Medien
    Digitale Medien
    The origin and development of alopecia in mice homozygous for strong's luxoid geneThis work was supported by research grant AM-06428 from the National Institute of Arthritis and Metabolic Diseases, Public Health Service, and by a grant made to M. L. Fritts by the Institute of Science and Technology, State of Michigan. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 118 (1966), S. 565-579 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Hair follicles are initiated in mice homozygous for Strong's luxoid gene at the normal times. The dermis from 16 days of gestation to nine days after birth lags in development. The adipose layer instead of enlarging at the normal time of three days after birth delays until nine days. The growth of the first cycle hairs is inhibited, particularly on dorsal surfaces. Some follicles of all types degenerate. The surviving follicles enter telogen at seven days after birth, after forming only short unpigmented or poorly-pigmented hairs. Many follicles immediately begin a second cycle of growth, in which more normal hairs develop and a substantial adipose layer forms. No alopecia develops on ventral surfaces, but growth of the first cycle ceases and the second cycle commences earlier than normal; the hairs formed are abnormal. Abnormal hair growth in Strong's luxoid homozygotes may be a result of the retarded growth of the dermis or both defects may be secondary to a more fundamental defect.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051180409
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  • 90
    Digitale Medien
    Digitale Medien
    Oviducal anatomy and sperm storage structures in lizards (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 7-19 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Gross and histological examination of lizard oviducts was made in 11 species of the family Iguanidae, and in one species of each of the families Gekkonidae and Eublepharidae. Lizard oviducts are bound dorsally by a mesentery which is continuous with the peritoneum, and ventrally by a smooth muscle band which extends from the posterior segment of the vagina to the base of the infundibular ostium. The musculature of the vagina consists of an inner circular smooth muscle layer which is thickened posteriorly, and an outer longitudinal layer which is arranged into longitudinal folds at about the utero-vaginal transition. In iguanid lizards the vaginal mucosa is arranged into longitudinal folds that extend the entire length of the vagina. Posteriorly, the folds are high and reduced in number. Anteriorly, they decrease gradually in height and become more numerous. In Phyllodactylus homolepidurus fold height and number remain essentially constant through the vagina. Seminal receptacles in the iguanids occur principally in the anterior segment of the vagina. Receptacles in P. homolepidurus (Gekkonidae) and Coleonyx variegatus (Eublepharidae) appear to be confined to the tube between the uterus and the infundibulum. Most receptacles are located adjacent to the oviducal mesentery and to the smooth muscle band.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190103
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  • 91
    Digitale Medien
    Digitale Medien
    Neurosecretory cells in the central nervous system of the adult blowfly Phormia regina meigen (diptera: Calliphoridae)This investigation was supported in part by a Public Health Service Research Career Award 5-K6-GM-18,495--01 through 03 from the National Institute of General Medical Sciences, and by Public Health Service Research grant Al-00533 from the National Institute of Allergy and Infectious Diseases, both made to G.F. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 21-37 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: 1Neurosecretary cells in the central nervous system of the adult blowfly, Phormia regina Meig., have been examined histologically using the parparaldehyde-fuchsin and Gomori's staining method. Six groups of the neurosecretory cells occur in each hemisphere of the brain, the medial, frontal, lateral A, lateral B, posterior I and posterior II groups. In the subesophageal ganglion, four B-cells and two A-cells are present. In the thoracico-abdominal ganglion, ten A-cells are found in the thoracic region and a total of about 50 A- and B-cells in the hind part of the abdominal region.2A comparison with the neurosecretory system of two other species of blowfly, Calliphora erythrocephala Meig., Sarcophaga bullata Parker, and the housefly, Musca domestica L., showed similar arrangements and grouping.3Neurosecretory granules have been observed along the axons originating from the medial neurosecretory cells of the brain, and the thoracico-abdominal ganglion. The granules originating from the medial groups can be traced directly to the corpus cardiacum from which they move to the aorta, crop duct and cardia through axons.4There is with advancing age a gradual increase in the size of cell bodies and nuclei of the median neurosecretory cells in both females and males of Phormia regina, and also a decrease in stainable granules. This increase in size is dependent on nutrition, with no increase in water alone, a slight increase on sugar, and a maximum increase on sugar and liver. Corresponding increases in size occur in the ovaries in connection with feeding the same substances.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190104
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  • 92
    Digitale Medien
    Digitale Medien
    The megachiroptera and vespertilionoidea of the microchiroptera (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 101-119 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The structure of the external ears and the ultrasonic cries produced by one member of the single family of Megachiroptera and six representatives of the Vespertilionoidea of the Microchiroptera have been described. All the specimens were intra-vitally fixed and the preparations have been examined, photographed and measured. Brief notes are given on the middle ear and the following measurements have been made on the cochlea: the general size of the cochlea in various dimensions, the width and thickness of the basilar membrane, the size of the spiral ligament and the height of the cells of Claudius. In conclusion it can be said that there are marked differences in the structure of the cochleae of the two suborders, as well as within the superfamily Vespertilionoidea.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190202
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  • 93
    Digitale Medien
    Digitale Medien
    Chemoreceptor sensillum structure in LimulusThe light microscopy is part of a thesis submitted by the author in partial fulfillment of the requirements for the Ph.D. degree in the Department of Biology, Lehigh University.The light microscopy was supported by U.S.P.H.S. grant NB-01389 awarded to Saul B. Barber, Lehigh University, by the National Institute of Neurological Diseases and Blindness. The electron microscopy was supported by U.S.P.H.S. Postdoctoral Fellowship 1-F2-GM-22,073-01 from the National Institute of General Medical Sciences. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 121-141 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The chemoreceptors of Limulus polyphemus (L.) are polyneuronal sensilla found in the spines of the coxal gnathobases of each walking leg, the spines of the chilarial appendages, and the chelae of all the limbs. Each sensillum contains 6-15 bipolar sensory cells that share a single pore in the cuticle. The dendrites of the sensory cells of each sensillum course to the cuticle together. These attenuate sharply and enter a canal in the cuticle as a very narrow terminal thread. The dendrites retain their identity in the thread, but with the light microscope, they are usually not visible individually. Each thread, consisting of 6-15 dendrites, is accompanied to the cuticular surface by a cuticular tubule found within the canal. The chemoreceptor sensilla of the gnathobase, chilarium, and chela, the temperature organs of Patten, and the flabellar receptor organs all have the same basic organization. In general this is the same structural plan shown by chemoreceptors of other arthropods. Several different mechanisms of peripheral physiological interaction among receptor cells are possible with a sensillum organization like that described here for Limulus.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190203
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  • 94
    Digitale Medien
    Digitale Medien
    Some cytologic characteristics of the hemocytes of Limulus during clottingThis investigation was supported by grant GM 08776-05 from the National Institutes of Health, United States Public Health Service. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 181-207 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The hemolymph of the horseshoe crab, Limulus (Xiphosura) polyphemus, contains a single cell type. The hemocytes are ovoid and contain many refractile granules. One-half to one minute after the onset of clotting the hemocytes swell and a hyaline cytoplasmic ring, essentially devoid of granules, appears about their circumference. During this time the granules disperse and the nucleus becomes visible. Three to five minutes following the initiation of clotting, the cell extends long pseudopodial processes. Phase contrast time-lapse cinematography reveals that the cells are extremely motile during this phase. Concomitant with these changes, many of the granules lose their refractility and one by one disappear from the cytoplasm leaving what appears to be a vacuole.Electron micrographs of native (un-clotted) hemocytes and of clots fixed in glutaraldehyde and post-fixed in osmium reveal that the membrane-bounded granules of native cells are very dense and homogeneous with no evidence of an internal structure. One-half to one minute after clotting, however, they become less dense and 250 Å microtubules spaced at ca. 500 Å intervals appear parallel to the long axis of the granule. Further degradation of the granule ensues and involves (a) change to a spherical shape, and (b) further decrease in density and better resolution of the microtubules. The microtubular component subsequently disintegrates leaving a membrane-bounded granule containing particulate material. Finally, the membrane of the granule fuses with the plasma membrane and the components of the granule are dispersed in the plasma where they presumably contribute to the formation of the gelatinous clot.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190206
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  • 95
    Digitale Medien
    Digitale Medien
    Segmental musculature and locomotion in Hermodice carunculata (polychaeta: Amphinomidae) (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 259-276 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The segmental muscles in the intestinal region of the body of Hermodice carunculata are described as well as the gross anatomy of the associated nervous system.The form of normal locomotion and the characteristic alarm reaction are described and interpreted in terms of fluid pressure within the body cavity and the action of appropriate groups of segmental muscles.Brief remarks on the habits of H. carunculata conclude the paper.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190211
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  • 96
    Digitale Medien
    Digitale Medien
    Masthead (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190401
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  • 97
    Digitale Medien
    Digitale Medien
    The ganglion-connective junction in the central nervous system of the leech, Hirudo medicinalisSupported in part by Research grant GM-10182 from the Institute of General Medical Sciences, National Institutes of Health, United States Public Health Service and in part by Research grant GB-3593 from the National Science Foundation. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 417-423 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Classical studies of the nervous system of the leech revealed that there were specific types of very large glial cells associated with various parts of the neuron. Recent microelectrode studies demonstrated that there was a low resistance to the flow charge from any one of these large glial cells to another. The present study describes a previously unreported type of glial cell, the glial cell of the fascicles. These cells, which resemble the glial cells of the connectives but are smaller, are found in the fascicles of axons that unite the connectives to the neuropil. Thus, these cells are located between the glial cells of the connectives on the one hand and the glial cells of the neuropil and packets on the other and must be taken into account in considerations of the low resistance to the transfer of charge from one glial cell to another.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190403
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  • 98
    Digitale Medien
    Digitale Medien
    Masthead (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 120 (1966) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051200101
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  • 99
    Digitale Medien
    Digitale Medien
    Number of nucleoli in various cell types of the mouse (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 119 (1966), S. 425-433 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The nucleoli of cells of the adult mouse were examined by staining with toluidine blue after removal of deoxyribonucleic acid from tissue sections by deoxyribonuclease treatment.The nuclei of each cell type examined contained one or more nucleoli. This was observed even in lymphocytes and neuroglia, although these cells have occasionally been described as anucleolated. In mature spermatids and spermatozoa, however, it was not possible to detect a nucleolus.The distribution of the number of nucleoli in many diploid cells exhibited a mode of two or three nucleoli per nucleus, and a range from 1 to 6 nucleoli.In presumedly diploid hepatic nuclei, the maximum number of nucleoli was six; but in presumedly tetraploid hepatic nuclei, it was 11. Thus, nearly twice as many nucleoli are present when the chromosome number is doubled. In view of this observation, it is suggested that six nucleolar organizers are present in the diploid chromosomal complement of the mouse. However, through failure of some nucleolar organizers or more probably through fusion of nucleoli, the number of these organelles in most nuclei is less than six.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051190404
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  • 100
    Digitale Medien
    Digitale Medien
    Masthead (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 120 (1966) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051200301
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