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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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    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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  • 48
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    Contraction and Treewidth Lower Bounds (2004)
    Details
    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
    Materialart: reportzib , doc-type:preprint
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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)
    Details
    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)
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    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)
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    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
    Materialart: reportzib , doc-type:preprint
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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
    Masthead (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967) 
    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.1051210101
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  • 59
    Digitale Medien
    Digitale Medien
    Intramitochondrial transformations during oocyte maturation in the mouseThis investigation was supported by a Public Health Service research grant (GM 12706-02) from the National Institute of General Medical Sciences, and a research career program award (5-K3-HD-5356-03) from the National Institute of Child Health and Human Development. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967), S. 29-45 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: An electron microscope study of oocyte maturation in the mouse revealed that some mitochondria undergo gradual transformation in their ultrastructural appearance. In very young oocytes these mitochondria were already found to contain vacuoles, one in each such organelle. In somewhat older oocytes more mitochondria displayed vacuoles which generally appeared to be getting larger. These intramitochondrial vacuoles were found to be essentially optically empty structures surrounded by a single membrane. In favorable sections someof the developing vacuoles had a bottle-shaped appearance, the constricted end of which was attached to the inner limiting membrane of the mitochondrion. With further maturation of the oocytes vacuoles having a pear-shaped appearance became evident. An hypothesis was presented outlining the mode of formation of these vacuoles by expansion of the individual cristae. Intramitochondrial transformations occuring during both oogenesis and spermatogenesis in mammals were reviewed.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051210104
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  • 60
    Digitale Medien
    Digitale Medien
    A morphological study of Luciocephalus pulcher, with notes on gular elements in other recent teleosts (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967), S. 103-133 
    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 monotypic perciform suborder Luciocephaloidei possesses the following, previously unknown, salient morphological characters: a third joint, the nasopalatopterygoid, between neurocranium and suspensorium; a toothless and dorsally exposed prevomer; no pharyngeal processes on either parasphenoid or basioccipital; a tympanum-covered foramen exoccipitale in the saccular bulla as a hearing organ; a gular ossification; a craniovertebral joint with small exoccipital condyles widely separated from the basioccipital condyle; and a large physoclystic swimbladder with a notable caudal extension. The seemingly functionless gular-like mental ossification is considered a paleomorphic structure with a neogenetic development. Attenuation in longitudinal growth is evident in the derivatives and dermal additions of the mandibular arch and nasal capsule while other regions of the head have remained independent. The primary adaptive significance of the attenuation in the growth of the entire preorbital region is the accomodation of oral incubation. Secondarily the elongate jaws increase both the speed and grasping range of the bite in prey catching. The degree of jaw protrusion depends mainly on the length of the maxillary. The exaggerated length of the ascending processes of the premaxillaries may be the result of a positive differential growth rate within one growth field. The meaning of the preponderance of parallel-fibered cranial muscles is discussed in respect to holding functions, greatest possible excursion of the insertion with minimum loss of force, and muscle fiber length. Based on the overall morphology, the monotypic suborder Luciocephaloidei is retained.
    Zusätzliches Material: 23 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051210203
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  • 61
    Digitale Medien
    Digitale Medien
    Functional morphology of the head of the anabantoid teleost fish Helostoma temmincki (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967), S. 135-157 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Osteology, myology and motion analysis of the head of the anabantoid fish Helostoma temmincki, a specialized filter feeder, has revealed six functional units: neurocranium, suspensory apparatus, opercular apparatus, hyoid apparatus, branchial apparatus and pectoral girdle. Interactions between the functional units take place through four couplings involved in opening and protruding the jaws. The first coupling is activated in the beginning of the opening cycle by the levator operculi muscle through the opercular apparatus, interoperculomandibular ligament and mandible. The second is activated during feeding by contraction of the sternohyoideus through the hyoid apparatus, interopercular, interoperculomandibular ligament and mandible. The third coupling is active during feeding and “kissing” by contraction of epaxial muscles through mediation of the neurocranium to the jaw apparatus. The fourth coupling is the only one active during air intake and involves contraction of the levator arcus palatini which abducts and rotates the suspensory apparatus forwards, causing the mandible to drop. The retention of isolated ancestral characters during mosaic evolution are explained in terms of the maintenance of couplings which represent functional associations of seemingly remote structures. When natural selection acts on one component of a functional unit or coupling, it essentially acts on all associated elements simultaneously causing character complexes to evolve in common evolutionary trends. It is feasible that functional analysis can separate primary from secondary evolutionary trends.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051210204
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  • 62
    Digitale Medien
    Digitale Medien
    Biomechanics of prehensile oral mucosaThis investigation was supported by United States Public Health service grant, DE-01849. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 122 (1967), S. 89-114 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Large dogs are able to deliver a powerful bite that generates considerable stress in the anterior, prehensile part of the jaws.In the upper jaw most of the biting force is borne by the anterior teeth. The palatal mucosa provides little resistance to deformation. It is easily compressed and rather mobile.In the lower jaw, the mucosa covering the upper surface of the symphysis receives a sizeable portion of the biting force. It is firmly attached to the underlying bone and possesses special connective tissue arrangements that enable it to transduce locally applied pressure to tension distributed over a broad area.
    Zusätzliches Material: 21 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051220203
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  • 63
    Digitale Medien
    Digitale Medien
    Testicular characteristics of goldfish Carassius auratus, in nature and under diet limitationsThis study was supported by Grant A-3445 of the National Institutes of Health. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 122 (1967), S. 131-137 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Goldfish testes were nutritionally regressed in about 115 days regardless of season and without controlled light or temperature. A gonosomatic index (testes weight ″ 100/body weight) of the regressed fish was about one tenth that of spawning fish. The regressed testes were primarily composed of spermatogonia, spermatocytes, and connective tissue. Fish testes were maintained in a regressed state for over 200 days with no change in gonosomatic index. Fish with regressed testes appeared to be in a state of “pseudohypophysectomy” with respect to gonadotropin. Pituitary replacement and a diet of 5% of the body weight per day initiated spermatogenesis and brought the regressed testes to functional maturity in one month. The results suggest that spermatogonial proliferation and the maturation of sperm have different regulatory requirements.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051220205
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  • 64
    Digitale Medien
    Digitale Medien
    The failure of exoskeletons and endoskeletons (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 123 (1967), S. 1-16 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A theoretical analysis is made of the mechanical advantages of exoskeletons and endoskeletons. More complicated and realistic loading systems are considered than have been by previous authors. For all cases involving static loading, an exoskeleton would seem to be advantageous, but sometimes the advantage is quite small. If impact is considered, the advantage of exoskeletons becomes very much reduced, even on theoretical calculations; and it is likely that in life the advantage may be converted to a disadvantage, particularly in large active animals such as vertebrates.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051230102
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  • 65
    Digitale Medien
    Digitale Medien
    The recognition, distribution and ultrastructure of hydrozoan nerve elements (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 123 (1967), S. 43-61 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Silver stained Cordylophora were examined by light and electron microscopy, which provided a general picture of nerve cell forms and distribution for comparison with electron micrographs of osmium-fixed tissues from the same hydroid. Muscle, nerve and neurosensory components were studied in the nectophore of Nanomia (O. Siphonophora) and in the hydromedusae Sarsia and Euphysa by means of vital staining and optical and electron microscopy of epon sections; particular attention was given to relationships and interconnections between the cellular elements of the two marginal nerve rings. Mitochondrial size, numbers and types of vesicles and the occurrence of neurotubules and of parts of sensory cilia may provide useful ultrastructural clues for recognizing nerve elements, but serial sections are often needed to make identification conclusive.In Cordylophora and Nanomia, some neurites contain massed A vesicles (membrane-bounded dense granules) suggestive of neurosecretion (cf. reports on Hydra). However, a small type of A vesicle also occurs at synapses in Sarsia, indicating a probable role here in junctional transmission. Vesicles occur on both sides of some synapses (as previously reported for Cyanea) but on one side only in others, these being the first examples of polarized junctional ultrastructure in coelenterates.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051230105
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  • 66
    Digitale Medien
    Digitale Medien
    Masthead (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 123 (1967) 
    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.1051230301
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  • 67
    Digitale Medien
    Digitale Medien
    Studies on the rabbit appendix. I. Lymphocyte-epithelial relations and the transport of bacteria from lumen to lymphoid nodule (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 123 (1967), S. 231-249 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A correlated light and electron microscope study was made of lymphocyte-epithelial relations in the appendix of normal rabbits, ranging in age from one week to ten months. The lymphocyte migration into the epithelium was very slight at one week. The lymphocytes were increased considerably in number from two weeks to three months, grouping into unique nests in the epithelium. The basement membrane began to be penetrated by migrating cells at one week and bacame discontinuous in older animals. At one and two weeks, the epithelial cells contained glycogen, which disappeared at three weeks. Degenerating cells as well as bacilli were found in the epithelial cells and in the macrophages of the nodules. The varied appearance of bacilli in the macrophages indicates that they were being digested. The lymphocytes in the epithelium were larger, having less crowded cytoplasm as compared with those in the lymph nodules. Many lymphocytes were in deep folds of epithelial cells. There was evidence favoring an intracellular position for some lymphocytes in the epithelium.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051230304
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  • 68
    Digitale Medien
    Digitale Medien
    Experimentally induced variations in vitelline artery development and circulatory pattern in the early chick embryoPart of a doctoral dissertation presented to The Faculty of the Graduate School of Arts and Sciences of the University of Pennsylvania. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 123 (1967), S. 313-327 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: White Leghorn eggs were incubated to desired prevasular stages. Each embryo, upon its intact yolk and surrounded by albumen, was rolled from the shell into a sterile 50 ml beaker. In an uppermost position, the blastoderm was lightly stained with neutral red. Three types of localized cuts were made as indicated below, and the beaker-embryo unit placed in a sterile humidified chamber for further incubation. Results: (1) Unilateral cuts adjacent to the body and parallel with its axis blocked or suppressed formation of the vitelline artery on the cut side, even though healing occurred; (2) A specific site was found in the area pellucida opposite the sinus rhomboidalis which, when lightly cut perpendicular to the body axis, resulted in blockage or shifting of the final junction between aorta and vitelline artery as far cephalad as the thirteenth somite level. Formation of a dual final junction with the aorta also occurred. (3)Transverse cuts through the body axis and into the area pellucida bilaterally, frequently resulted in bilateral blockage or bilateral shifting. In still other cases, growth of a functional loop around the cut to connect the aortae in anterior and posterior segments with the vitelline artery were observed. Other unique circulatory patterns are described.Apparently, slight interference with the capillary plexus which precedes the vitelline artery causes anomalous development. Circulation is considered a major factor in arterial differentiation. Cutting probably alters the plexus and relation of its components to the onset of blood flow.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051230402
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  • 69
    Digitale Medien
    Digitale Medien
    The atrioventricular branches of the human coronary arteriesThe abstract of this paper was one of six selected among 380 for presentation at the plenary session of the American Association of Anatomists Meeting, March 31, 1964, Denver, Colorado. Publication supported by the Northwestern Ohio Heart Association. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 123 (1967), S. 397-403 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Branches of the coronary arteries of normal human hearts, supplying both atria and ventricles, were found by fine dissection and have been named rami atrioventriculares. They comprise atrial branches from ventricular arteries and ventricular branches from atrial arteries. Their incidence was 74% in the 50 adult individuals studied. The subjects had committed suicide with a poison which did not damage the coronary arteries. The atrioventricular branches constitute communications across the coronary sulcus, thus establishing a continuity between the atrial and the ventricular arterial supply. Therefore, there is not invariably a sharp demarcation of blood supply between atria and ventricles, as has been commonly taught. Neither atrial nor ventricular branches consist exclusively of ascending and descending branches of the coronary arteries, as has been assumed. Atrioventricular branches can play a role in collateral circulation and may, in individuals who are born with them, provide an explanation for some of the variability in signs and symptoms incidental to heart attacks.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051230406
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  • 70
    Digitale Medien
    Digitale Medien
    The post-embryonic changes in Melipona quadrifasciata anthidioides lep. (hym. apoidea) II. Development of the salivary glands systemThis research was supported by FG-Br-102, United States Department of Agriculture, P.L. 480 and Conselho Nacional de Pesquisas. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 123 (1967), S. 481-502 
    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 paper deals with the development of the salivary gland system in Melipona quadrifasciata anthidioides, which begins in the prepupal stage. The silk glands degenerate by autolysis at the end of the larval stage. Degeneration is characterized by cytoplasmic vacuolization and pycnosis of the nuclei of the secretory cells. The glandular secretory portion of degenerated silk glands separates from the excretory ducts. The salivary glands develop from the duct of the larval silk glands. The thoracic salivary glands develop from the ducts of the secretory tubules and the head salivary glands from the terminal excretory duct. The mandibular glands appear in the prepupa as invaginations of mandibular segments, and their differentiation to attain the adult configuration occurs during pupation. The hypopharyngeal glands have their origin from evaginations of the ventral anterior portion of the pharynx. A long tubule first appears with walls formed by more than one cellular layer. Then some cells separate from the lumen of the duct, staying attached to it by a cuticular channel in part intracellular. The initial duct constitutes the axial duct, in which the channel of the secretory cells opens. During the development of salivary and mandibular glands, they recapitulate primitive stages of the phylogeny of the bees. During the development of salivary glands system, mitosis accounts for only part of the growth. Most of the growth occurs by increase in size of cells rather than by cell division. In brown-eyed and pigmented pupae six days before emergence, the salivary gland system is completely developed, although not yet functioning.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051230410
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  • 71
    Digitale Medien
    Digitale Medien
    Functional morphology of the caudal region of certain clupeiform and perciform fishes with reference to the taxonomyBased on a thesis submitted in partial fulfillment for the requirements for the degree of Master of Science in the University of Hawaii, 1966. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 123 (1967), S. 529-558 
    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 caudal anatomy (caudal skeleton, musculature, vascularization, innervation, and urohypophysis) and swimming behavior of three clupeiform and three perciform fishes: Elops hawaiensis (Cupeiformes: Elopidae), Oncorhynchus nerka (Cupeiformes: Salmonidae), Chanos chanos (Clupeiformes: Chanidae), Kuhlia sandvicensis (Perciformes: Kuhlidae), Apogon menesemus (Perciformes: Apogonidae), and Gnathanodon speciousus (Perciformes: Carangidae), were studdied. The taxonomic significance of caudal structures was determined and evaluated by detailed examination of differences in caudal anatomy. An interpretation of functional significance of these differences was attempted by relating them to observed differences in swimming behavior. The swimming behavior was studied by the observation of swimming activities of fish while resting or cruising and while feeding in the aquarium, and by an analysis of each frame of an 8 mm movie film of swimming activities.There are certain consistent and basic differences between all three species of the order Clupeiformes and all three species of the order Perciformes in respect to caudal structures. Although certain caudal structures show overlapping in number and/or complexity of arrangement, they seem to indicate more complex structural organization in Clupeiformes than Perciformes. The differences confirm the conclusion of others that the order Clupeiformes is more “primitive” than the order Perciformes.With respect to caudal structures of the three clupeiform species studied, E. hawaiensis is the most “primitive” and, of the three perciform species studied, K. sandvicensis is the most “primitive.”Caudal structural variations from one species to another are related to the mode of adaptation to swimming as well as to the evolutionary status of the species.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051230412
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  • 72
    Digitale Medien
    Digitale Medien
    The tectorial membrane of the lizard ear: Species variationsThis investigation was supported by grants from the National Institute of Neurological Diseases and Blindness, Public Health Service, and was aided by a contract with the Office of Naval Research and by Higgins funds allotted to Princeton University. Permission is given for reproduction and use by the United States Government. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 123 (1967), S. 355-371 
    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 forms of the tectorial membrane and its connections to the ciliary tufts of the hair cells have been studied in detail in 18 species of lizards and, less thoroughly, in three others. This group, which represents eight lizard families, exhibits three forms of tectorial membrane: a complete form that connects to all parts of the auditory papilla, an abbreviated form that makes this connection only in one limited region of the papilla, and a dendritic form in which the distal portion of the membrane subdivides into strands reaching all the hair cells.Sometimes the tectorial membrane connects directly with the tufts of the hair cells, but more often it makes this connection through intermediary structures. Seven types of such intermediary structures have been identified (if we include the sallet, which is not “intermediate” in a strict sense).Detailed descriptions are given of the various forms of tectorial membrane structures and their variations along the auditory papilla in 12 lizard species. The description for Iguana iguana is offered as representative of the iguanid pattern found in ten members of this family.Consideration is given to the functioning of the tectorial membrane, and also of the sallet, in the process of hair-cell stimulation.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051230404
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  • 73
    Digitale Medien
    Digitale Medien
    Lymphomyeloid organs of amphibia. II. Vasculature in larval and adult Rana catesbeianaSupported mainly by funds from USPHS grant AM 09030-03 from the National Institute of Allergy and Metabolic Diseases. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 123 (1967), S. 463-479 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: There were no lymphatic vessels and lymph nodes demonstrable in adult and larval Rana catesbeiana by a method that adequately demonstrated the same in mammals. Although the parenchymal arrangement in the lymphomyeloid organs is not exactly the same as in mammalian hemal nodes, nonetheless the vascular patterns of the lymph glands and jugular bodies are prima facie evidence that they function as blood-filtering organs among other probable functions. The vascular pattern of the lymph gland is that of a rete mirabile, particularly a venous portal system, inasmuch as the afferent and efferent vessels are venous in character and interposed between them is a labyrinth of sinusoids. This is not the case, though, in the adult organs. The vascular pattern of the jugular bodies is very much like the spleen, viz., artery-capillary-sinusoid-vein sequence. It is doubtful, however, if the propericardial and procoracoid bodies ever filter blood, because the smallest blood vessels in them are capillary in type Because of the absence of a well-defined capsule in some parts of the propericardial body, similarly to lymphoid follicles, especially in the mammalian gastrointestinal tract, it is probable that it filters tissue fluid. The last two organs are apparently mainly blood cell-forming organs. It is inferred from the vascular connections of the larval and the adult lymphomyeloid organs that they are not genetically related. This aspect was analyzed from earlier developmental data, but actual follow-up of the larval organs to the adult stage is still in progress.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051230409
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  • 74
    Digitale Medien
    Digitale Medien
    The microscopic structure of the adult raccoon (Procyon lotor) and woodchuck (Marmota monax) spleensThis investigation was supported, in part, by a Public Health Service Research grant 1-FI-CM-22,600-01 (Pre-Doctoral Fellowship) from National Institutes of Health, Bethesda, Maryland. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967), S. 47-54 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Histological serial sections of spleens from the adult raccoon (Procyon lotor) and woodchuck (Marmota monax) were processed for microscopic examination. Observations related to various aspects of the internal vascular pattern in the spleen of the raccoon and woodchuck demonstrated features that were characteristic of the respective animal. The spleen of the raccoon possess well-developed ellipsoid sheaths, whereas these same structures were not as prominent in the spleen of the woodchuck. The spleen of both mammals examined demonstrated the presence of an anastomosing series of venous sinuses within the red pulp tissue and may be classified as sinusal in nature.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051210105
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  • 75
    Digitale Medien
    Digitale Medien
    Masthead (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967) 
    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.1051210201
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  • 76
    Digitale Medien
    Digitale Medien
    The division and differentiation of Drosophila cystocytes (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967), S. 55-70 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Light and electron microscopical studies allow a descriptive account to be given of he morphogenesis of the egg chamber of Drosophila melanogaster. The study demonstrates that the mitotic products of a single cystoblast generate a branching chain of 16 inter-connected cystocytes. Two specific cystocytes enter meiotic prophase, while the rest become nurse cells. The two pro-oocytes form synaptinemal complexes in their nuclei. However, one of the two cells later switches back into the nurse cell developmental pathway. The elongation of the synaptinemal complexes is described, and estimates are made of the time involved in their formation. These complexes continue to be synthesized long after the DNA replication which gives the oocyte its 4C DNA content. This finding implies that at least some genetic crossing over follows DNA replication. Evidence is presented that cells undergoing crossing over are most efficient in repairing radiation-induced chromosomal breaks. Suggestions are given as to the mechanisms by which (1) cell division is inhibited once 16 cystocytes are formed, (2) the future cleavage planes of cystocytes are programmed, (3) the pro-oocytes are differentiated from nurse cells, and (4) the oocyte is chosen from the twin pro-oocytes. The contrasting behaviors of the oocyte and nurse cell nucleoli are described. During oogenesis nucleolar synthesis of ribosomal RNAs is suppressed in the oocyte and concurrently stimulated in the nurse cells. It follows that the nurse nuclei are the major sources of the prodigious quantities of ribosomes found in the ooplasm of the mature oocyte.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051210106
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  • 77
    Digitale Medien
    Digitale Medien
    The morphology and function of accessory reproductive glands in the lophophores of Phoronis vancouverensis and Phoronopsis harmeriThis work was submitted to the Graduate Faculty of the University of Washington, Seattle, Washington, in partial fulfillment of the requirements for the degree of Doctor of Philosophy. The research was completed at the Friday Harbor Laboratories, Friday Harbor, Washington, and was supported in part by an NSF Summer Training Grant and by NSF Intermediate (#28218) and Terminal Year (#39202) Fellowships. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967), S. 159-178 
    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 enigmatic lophophoral organs of phoronids are demonstrated to by accessory sex glands. In the hermaphroditic Phoronis vancouverensis, each mature adult has two pairs of such glands: female nidamental glands that facilitate the temporary brooding of the embryos and male accessory spermatophoral organs that function in spermatophore elaboration. Functional males of Phoronopsis harmeri have complex accessory spermatophoral organs while females of this non-brooding dioecious species lack accessory sex glands.In both species, coelomic spermatozoa are accumulated within the nephridia and passed en masse into the partially enclosed spermatophoral organs. There each sperm mass is molded into a characteristic shape and encased in one or more membranes before release as a spermatophore into the ambient water. The structure of the spermatophore is characteristic for each species and is correlated with the functional morphology of the distinctive spermatophoral organs.The existence of spermatophores, the non-primitive nature of the spermatozoa, and additional features of reproductive biology dictate that fertilization is internal in these species, but attempts to determine the means of sperm transfer proved futile. Reproductive potential and behaviour of male Phoronopsis, means of gamete segregation in Phoronis, and general pattern of reproductive biology for both phoronids were also studied.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051210205
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  • 78
    Digitale Medien
    Digitale Medien
    Tissue dynamics of steady state growth in Hydra littoralis. II. Patterns of tissue movement (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967), S. 19-28 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In the column of hydra, tissues continually move away from a region located just underthe whorl of tentacles. Above this subtentacular region, tissues proceed into the hypostome and tentacles; below it tissues pass into the buds or continue down the stalk. These movements represent a steady state pattern of tissue renewal in which column growth is balanced by tissue loss at the body extremities. But the existence of a subtentacular zone in which tissue appears stationary does not necessarily indicate that growth is restrictedto this region, as is commonly stated.The body column of hydra can be viewed as an expanding cylinder whose elongation is balanced by tissue loss at the two ends. In such a body there must be one region from whichtissue appears to emanate, regardless of how growth is distributed along the cylinder. Only the rates at which tissues move will be characteristic of the underlying growthpattern. In Hydra littoralis, the measured rates of tissue movement down the gastric column are consistent with the distributions of mitotic figures, which indicate that growth is spread out along the column.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051210103
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  • 79
    Digitale Medien
    Digitale Medien
    Mathematical approach to measurements on embryonic chick lens (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967), S. 71-80 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Profiles of fresh chick lenses of 5, 8, 11, 14, 17 and 20 days embryological age were photographed and from tracings of these profiles, volumes were calculated using a formula for volume of a solid of revolution. Accurate volumes were also obtained by assuming the lens to be two half oblate spheroids of different minor axis, or, better, two half-solids of profile (x/a)k + (y/b)k = 1. In addition, the k in this equation described well the curvature of the lens profiles and thus provided a quantitative measure of developing lens shape. Lens diameter, depth and shift of equatorial diameter upon lens axis as a function of age were also studied.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051210107
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  • 80
    Digitale Medien
    Digitale Medien
    Cytological studies of the ductuli efferentes of the opossumSupported by Southern Illinois University Special Research Project no. 2-17-17 and U. S. Public Health Service grant CA-05310 from National Cancer Institute. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967), S. 81-101 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Ductuli efferentes in four examined genera of family Didelphidae are organized into highly convoluted tubules, located within a conical body adjacent to the vascular plexus supplying the testis. They have yellowish-green color in the adult Didelphis virginiana and grey pink color in other genera. The ductuli efferentes in all examined animals are lined by very low columnar cells, covered by microvilli or booth cilia and microvilli.Histochemical analysis reveals several types of cytoplasmic granules in the genera examined. A single sperical body about 1.5 μ in diameter is found in epithelial cells of the four eyed opossum (genus Philander); this body stains positively for RNA and non-histone protein, and appears granular under the electron microscope, without a limiting membrane. Abundant cytoplasmic bodies in the Virginia opossum show strong reactions for SH groups; these granules may be responsible for the green color of the ductuli in this species. Ultrastructural studies show that the morphology of membrane limited granules in the ductuli of the examined genera is characteristic for each genus. Abundant pinocytotic vacuoles in the apices of these cells and a strongly positive alkaline phosphatase reaction suggest a marked absorptive activity of epithelial cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051210202
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  • 81
    Digitale Medien
    Digitale Medien
    Correlation of the development of membranous and bony labyrinths, acoustic ganglia, nerves, and brain centers of the chick embryo (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967), S. 179-207 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Detailed descriptions are presented of morphogenetic and histogenetic events occurring in the membranous and bony labyrinths, sensory areas, acoustic ganglia, and acoustic centers of the hindbrain of the chick embryo, stages 11 to 45. Major morphogenetic changes occur between stage 11 and stage 30. During this period primordial ganglionic neuroblasts are segregated from the otic epithelium and differentiate into the bipolar neuroblasts of the vestibular and cochlear ganglia, neuroblasts of the alar plate in the acoustic region of the rhombencephalon differentiate, migrate, and are organized into acoustic nuclei, and the otic cup closes to form a vesicle which undergoes complicated structural changes to become a labyrinth. Morphological events in neural structures are closely followed by structural changes in the labyrinth. Minor morphological changes continue to occur through stage 44. The histogenetic period, stage 26 to 38, is the same for all parts of the acoustic apparatus. Minor histogenetic events occur up to hatching. In this period, differentiation of ganglionic and central neurones precedes differentiation of sensory cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051210302
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  • 82
    Digitale Medien
    Digitale Medien
    Masthead (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967) 
    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.1051210401
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  • 83
    Digitale Medien
    Digitale Medien
    Studies on the neurosecretory system of Ranatra elongata fabricius (Hemiptera: Nepidae) with reference to the distal fate of NCC I and II (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967), S. 223-239 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: With the help of PF and PAVB bulk-stained preparations and sections the neurosecretory system of Ranatra elongata has been described. Two medial, each of 9-10 cells, and two lateral, each of 3-4 cells, groups of neurosecretory cells have been observed in the protocerebrum. Only the A-cells have been found to be positive to PAVB histo- and cyto-chemical technique. Axons of the A-cells after traversing the proto- and deuto-cerebrum emerge from the tritocerebrum as the NCC I. The NCC I after bypassing the corpora cardiaca penetrate the aorta wall. There is no physical continuity between the corpora cardiaca and the NCC I and the two are separable. The NSM from the A-cells, transported by their nerve fibers, has been observed in the aorta wall. On the basis of large accumulation on NSM in the aorta wall the latter has been considered as the storage-and-release organ for the A-material. Corpora cardiaca are found to be devoid of A-material. Axons from the B-cells, after emergence from the tritocerebrum as the NCC II, have been observed to penetrate the corpora cardiaca. On the basis of ample amounts of B-material the glands have been considered as the storage-and-release organ for the B-material only.Observations are compared with results on related species and it is concluded that two independent organ complexes constitute the neurosecretory systemt of R. elongata. The A-cells, their pathways, the NCC I, and the aorta wall comprise the first; and the B-cells, their pathways, the NCC II, and the corpora cardiaca the second. The former is concerned with the elaboration, transportion, storage-and-release of the A-material and the latter with the B-material. Finally arguments are presented to include the aorta wall in the neurosecretory system.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051210304
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  • 84
    Digitale Medien
    Digitale Medien
    The carotid sinus in lizards with an anatomical survey of the ventral neck region (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967), S. 311-321 
    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 anatomy of the ventral neck region of the scincid lizards Chalcides ocellatus and Scincus scincus is presented and is found to be similar to that of other lizards as described in the literature. The internal carotid artery arises by 3-5 roots from the dorsal side of the ascending limb of the carotid arch. During its first part, the internal carotid artery is completely divided into two nearly equal channels. The carotid sinus is more complicated in Chalcides than in Scincus. In lizards, it may be homologous to the carotid labyrinth of fishes and amphibians. Around the origin of the internal carotid artery are two kinds of epithelioid cells scattered in the adventitial connective tissue: a- large cells with rounded, faintly stained nuclei, and little, clear cytoplasm; b- cells with small darkly stained nuclei. Both kinds of cells appear to represent different levels of secretory activity. The number of the large cells increases with greater complexity of the carotid sinus. The cells also increase in size and number during summer (sexual period); this is especially true in younger animals. The epithelioid cells are considered to be homologous to the carotid body of higher vertebrates. The carotid sinus and epithelioid cells together form a closely interrelated system which may be intermediate between the carotid labyrinth of fishes and amphibians, and the carotid body of birds and mammals.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051210405
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  • 85
    Digitale Medien
    Digitale Medien
    Fine structure of nerve cells in a planarianThis work was supported by a grant from the National Cancer Institute (TICA-5055), National Institutes of Health, Department of Health, Education, and Welfare. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967), S. 323-337 
    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 fine structure of the nerve cell types in the white planarian Procotyla fluviatilis were described. Ganglion cells comprise the major portion of the brain. These cells are irregular in shape with several cytoplasmic processes and contain ribosomes, a sparse endoplasmic reticulum, microtubules, lysosomes, and a Golgi apparatus with numerous small vesicles. Granule-containing cells are situated in the peripheral regions of the brain and along the nerve cords. These cells contain ribosomes, rough-surfaced endoplasmic reticulum and a Golgi apparatus with associated dense granules. The granules occupy most of the cytoplasm and are ∼ 750A in diameter with moderately dense contents, ∼ 750A with opaque contents, and ∼ 1000A with contents of medium density. These granules are similar to those in the nervous systems of higher animals that contain epinephrine, norepinephrine, and neurosecretory substance, respectively. Each cell contains predominantly one type of granule although there is some intermixing of granules and intermediate types between the three most abundant granules. Small clear vesicles, resembling cholinergic synaptic vesicles, and all types of dense granules occur in the neuropil and within nerve endings.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051210406
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  • 86
    Digitale Medien
    Digitale Medien
    Ingestion of particulate matter by the outer surface cells of the mollusc mantleThis investigation was supported (in part) by grant DE-01825 from the N.I.D.R., U.S.P.H. Service. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 122 (1967), S. 139-145 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A study of the ingestion of particulate matter from the pallial space located between the shell and the outer surface of the mantle of Isognomon alatus and Pinctada radiata was undertaken with the aid of the electron microscope. For this purpose colloidal thorium dioxide (thorotrast) was introduced into the pallial space for periods of 1-5 days after which time the mantle was excised and prepared for examination with the electron microscope. After 24 hours thorotrast micelles were observed in the pallial space, on the surface of the microvilli, in small pinocytotic vesicles between the bases of the microvilli, in vacuoles undergoing coalescence and finally in large dense bodies (lysosomes). Amoebocytes in the pallial space also participate in the removal of particulate matter in a manner similar to that described for the surface epithelium. During active ingestion the Golgi apparatus changes from a vesicular to a lamellar form. The method of ingestion observed in the surface epithelia and the amoebocytes is similar to the ingestion of protein and other particulate material reported for a variety of vertebrate tissues.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051220206
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  • 87
    Digitale Medien
    Digitale Medien
    Histochemical patterns in the proventriculus of the developing chickSupported by USPHS grant AM-05429, National Institute of Arthritis and Metabolic Diseases. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 122 (1967), S. 231-247 
    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 proventriculus of White Leghorn chick embryos (stages 29-45) newly-hatched chicks, and adult chickens were frozen, sectioned in a cryostat and treated histochemically to identify localizations of alkaline and acid phosphatase, adenosine triphosphatase, 5-nucleotidase, nucleotide-diphosphatase, non-specific glycerophosphatase, glucose-6-phosphatase, non-specific esterase and succinic dehydrogenase. Ribonucleic acid, proteins and acid mucopolysaccharides were identified in tissues fixed in FAA.Acid phosphatase, nucleotide-diphosphatase, adenosine triphosphatase, succinic dehydrogenase, ribonucleic acid and proteins were present in the cells of the deep glands at all stages of development. Alkaline phosphatase and 5-nucleotidase were found only in mesenchymal derivatives of the proventriculus. After the chick begins swallowing and digesting albumen, enzymatic activity increased and non-specific esterase became very reactive.The surface epithelium is covered with a mucous coat. Ribonucleic acid, non-specific esterase, acid phosphatase and nucleotide-diphosphatase were localized in the basal portions of the epithelial cells. The functional significance of these different patterns is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051220305
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  • 88
    Digitale Medien
    Digitale Medien
    Functional morphology and evolution of tail autotomy in salamanders (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 122 (1967), S. 265-305 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Basal tail constriction occurs in about two-thirds of the species of plethodontid salamanders. The constriction, which marks the site of tail autotomy, is a result of a reduction in length and diameter of the first caudal segment. Gross and microscopic anatomical studies reveal that many structural specializations are associated with basal constriction, and these are considered in detail. Areas of weakness in the skin at the posterior end of the first caudal segment, at the attachment of the musculature to the intermyotomal septum at the anterior end of the same segment, and between the last caudosacral and first caudal vertebrae precisely define the route of tail breakage. During autotomy the entire tail is shed, and a cylinder of skin one segment long closes over the wound at the end of the body.It is suggested that specializations described in this paper have evolved independently in three different groups of salamanders.Experiments and field observations reveal that, contrary to expectations, frequency of tail breakage is less in species with apparent provisions for tail autotomy than in less specialized species. The tail is a very important, highly functional organ in salamanders and it is suggested that selection has been for behavioral and structural adaptations for control of tail loss, rather than for tail loss per se.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051220402
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  • 89
    Digitale Medien
    Digitale Medien
    Masthead (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 123 (1967) 
    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.1051230201
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  • 90
    Digitale Medien
    Digitale Medien
    Ultrastructural differentiation of the epithelium and mucous glands of the esophagus in the chick embryoContribution no. 089 from the Institute of Molecular Evolution. This work was done while a NSF Science Faculty Fellow and was supported in part by USPHS grant AM-05429, National Institute of Arthritis and Metabolic Diseases, NASA grant number NsG-689 Institute of Molecular Evolution and NSF grant number GB 3899 to Dr. C. B. Metz. Embryos were provided by Dr. C. Grabowski. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 123 (1967), S. 121-131 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Esophagi of White Leghron chick embryos, six days to hatching, were fixed in 5% glutaraldehyde in a cacodylate-sucrose buffer, postfixed in 1% OsO4, dehydrated and embedded in Araldite. Tissues were sectioned with glass knives and viewed with a Philips EM 100C. The epithelium in early stages of development is characterized by small intercellular spaces, few cell processes and few desmosomes. In contrast the differentiated epithelium contains numerous cell processes, large intercellular spaces and numerous desmosomes. Mucin appeared in the mucous glands at 17 days.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051230203
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  • 91
    Digitale Medien
    Digitale Medien
    Masthead (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967) 
    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.1051210301
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  • 92
    Digitale Medien
    Digitale Medien
    Comparative responsiveness of supracaudal and other sebaceous glands in male and female guinea pigs to hormonesThis research has been aided by research grants GM-05335 and AM-03628 from the National Institutes of Health, United States Public Health Service. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967), S. 209-221 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Different types of sebaceous glands in guinea pigs were chosen to study their comparative responsiveness to steroid hormones. Glands selected were (1) Sebaceous glands associated with rudimentary hair in the supracaudal gland; (2) Free sebaceous glands of the nipple; (3) Sebaceous glands associated with the hair. The results showed distinct differences in sensitivity among these different sebaceous glands and according to the sex of the experimental animal. The most responsive of the glands in males was the supracaudal gland; in the female the most responsive glands were the sebaceous glands of the nipple. Sebaceous glands associated with normal hair were relatively insensitive to changes in hormonal level. In all cases testosterone propionate was more potent in stimulating any of the sebaceous glands than progesterone. After gonadectomy, various sebaceous glands showed unequal states of depletion due to the different rates of differentiation and disintegration of their cells into sebum.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051210303
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  • 93
    Digitale Medien
    Digitale Medien
    Electron microscopy of the thymus in two species of snakes, Crotalus atrox and Lampropeltis getulusSupported by N.S.F. grant GB-4159 and U.S.P.H.S. grant FR-05423. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 121 (1967), S. 277-293 
    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 lymphoid cell population of thymus in the rattlesnake and king snake is similar to that of mammals. Lymphocytes occupy the interstices of an epithelial cell framework. An abudance of tonofilaments and desmosomes occupy the cytoplasm of epithelial cells with light, homogeneous nuclei and prominent nucleoli. Other epithelial cells contain phagocytized material in a dense cytoplasm which surrounds an irregular nucleus with heavily clumped chromatin. Small, granular vesicles are found within some epithelial cells.Myoid cells occur in the medullary area. In mature forms, myofibrils are arranged in a concentric fashion around the nucleus and occupy much of the cytoplasmic volume. The presence of developmental stages of these cells suggests their differentiation within the thymus of the adult animal.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051210403
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  • 94
    Digitale Medien
    Digitale Medien
    Masthead (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 122 (1967) 
    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.1051220101
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  • 95
    Digitale Medien
    Digitale Medien
    Morphological and histochemical studies on oogenesis in Callosobruchus analis Fabr. (Bruchidae-Coleoptera) (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 122 (1967), S. 19-33 
    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 ovary in Callosobruchus analis consists of telotrophic ovarioles with the so called nurse cells confined to one chamber at the anterior end of the ovariole. There are three types of lipids in the ovary: (1) L1 bodies that are present in the early oocytes, in the posterior prefollicular tissue and in the follicular epithelium and contain unsaturated phospholipids; (2) L2 bodies that have a complete or incomplete sheath of phospholipids and a triglyceride core; (3) L3 bodies that are formed of highly saturated triglycerides. Lipids are absent from the trophic tissue. In a mature oocyte the L1 and L2 bodies are cortical in distribution while the L3 bodies are centrally located.The mitochondria contain lipoproteins with RNA. The yolk spheres are acid mucopolysaccharides and protein in nature. The precursors of the yolk spheres appear first in the cortical coplasm and are absent from the follicular epithelium or the trophic tissue. The nucleolus of the oocyte shows evidence of extrusions that are believed to pass into the ooplasm.There are no nutritive cords connecting the trophic tissue to the oocytes; nor is there any evidence of any histochemically demonstrable nutritive material being contributed to the oocyte by the trophic tissue. The circumstantial evidence points towards a contribution of the raw materials to the oocyte by the haemolymph either through or in between the follicular epithelium in some soluble form or as submicroscopic particles.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051220103
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  • 96
    Digitale Medien
    Digitale Medien
    Splenomegaly and hemolytic anemia induced in rats by methylcellulose  -  an electron microscopic studyThis work was supported by grants Hema CA 5375-06 of thE United States Public Health service and a Training Grant of the National Institute of General Medical Sciences. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 122 (1967), S. 35-61 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Parenteral administration of methylcellulose causes massive splenomegaly and hemolytic anemia in rats. The red pulp of the spleen is markedly cellular due mainly to: (1) large numbers of voluminous free macrophages containing methylcellulose-induced vacuoles, (2) an increase in the number of plasma cells and (3) stasis of blood evidenced by a large number of erythrocytes and platelets in vessels, sinuses and cords. White pulp changes are usually less marked. Here the major change is the presence of macrophages containing methylcellulose-induced inclusions. The slow circulatory time in the spleen and the increase in macrophages may cause the hemolytic anemia observed in these animals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051220104
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  • 97
    Digitale Medien
    Digitale Medien
    Observations on the cervix uteri of the squirrel monkeyThis investigation was supported by NIH Resource grant FR 00180 and NIH grant HD 01357. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 122 (1967), S. 81-88 
    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 squirrel monkey uterine cervix was studied macroscopically and microscopically in intact and ovariectomized monkeys. The effect in ovariectomized monkeys of estradiol dipropionate or progesterone of both given after estrogen priming was studied by PAS staining.The lower portion of the cervix was dilated to form a vestibule into which projected fibromuscular colliculi which arose from the isthmic end of the cervix. The stratified squamous epithelium of the vagina was continuous through the external os with a similar epithelium lining the vestibule and covering the external surfaces of the colliculi. The transitional zone between the stratified epithelium and columnar cells was variable. The colliculi were covered internally with mucosal folds of columnar epithelium continuous with those of the endocervical canal.Glycogen concentration in the smooth muscle did not fluctuate markedly, irrespective of the hormones used. Glycogen granules were more numerous in the stratified squamous epithelium. Malt-diastase-resistant material appeared to be more abundant in the columnar epithelium and glandular lumina when the monkeys received both hormones than when they received solely estrogen or progesterone.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051220202
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  • 98
    Digitale Medien
    Digitale Medien
    Masthead (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 122 (1967) 
    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.1051220301
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  • 99
    Digitale Medien
    Digitale Medien
    Oxytalan fibers in the periodontal ligament of the Caiman and the Alligator (Crocodilia, Reptilia) (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 122 (1967), S. 169-173 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Histological examination of the fibrous and cellular connective tissue components of the periodontal ligament in the Caiman and the Alligator reveals the presence of reticular fibrillae, collagenic, elastic, and oxytalan fibers, as well as fibrocytes, osteoblasts, cementoblasts and epithelial rests. The oxytalan fibers differentiated by the peracetic acid aldehyde-fuchsin method are most numerous in the coronal region, radiating from the primary cementum into the periodontal ligament a short distance. Oxytalan fibers in fewer numbers are found interspersed between the oblique and the horizontal principal fiber bundles. Inasmuch as the crocodilian teeth have continuous replacement and thus a relatively short functional life, the oxytalan fibers of the Caiman and the Alligator appear to be proportionally fewer in number than they are in the mammalian periodontal tissues. The presence of the oxytalan fibers and epithelial rests in the Order Crocodilia (Crocodilia) adds to the number of dental structures shared with the Class Mammalia (Mammalia) (mammals) such as a stellate reticulum, a primary and secondary cementum and a periodontal ligament. This furnishes additional histological evidence for evaluation of the phylogenetic position of this group.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051220302
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  • 100
    Digitale Medien
    Digitale Medien
    Histochemical studies on cell death and histolysis during regeneration I. Distribution of acid phosphomonoesterase activity in the normal, the regenerating and the resorbing forelimb of the larval spotted salamander, Amblystoma maculatumSupported by grants (GM-05483 and AM-03605) from The National Institutes Of health, United States Public Health Service. (1967)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 122 (1967), S. 203-229 
    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, especially azo dye methods for detecting acid phosphomonoesterase activity were applied to normal, regenerating and denervated, amputated limbs from larval Amblystoma maculatum. Efforts were made to control inactivation of enzymic activity and diffusion of both enzyme and reaction product. “Base-line” values for enzymic activity were determined for normal limbs. Activity appeared most intense in macrophages, less intense in epidermis and cartilage matrix. Some activity was detected in Schwann cells, peri- and endoneurium and muscle fibers form normal limbs. Enzymic activity in regenerating limbs was strongest within macrophages which appeared in increased numbers especially in early stages. Wound tissue showed little increased activity. As the blastema formed, increased enzymic activity was detected in epidermis and within increased numbers of macrophages. Chondrocytes showed increased activity especially during cartilage matrix deposition. Amputated, denervated limbs showed large numbers of active macrophages beneath and within epidermis and along muscle. As regression commenced, areas of cartilage matrix breakdown showed increased enzymic activity but, in general, greatest activity was in macrophages. The various possible roles of acid phosphomonoesterase activity in the specific biological situations dealt with are considered in light of such observations.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051220304
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