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  • 2005-2009  (34)
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  • 1
    Publication Date: 2019-01-29
    Description: We consider an optimal control problem from hyperthermia treatment planning and its barrier regularization. We derive basic results, which lay the groundwork for the computation of optimal solutions via an interior point path-following method. Further, we report on a numerical implementation of such a method and its performance at an example problem.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 2
    Publication Date: 2016-06-09
    Description: Optical technologies are ubiquitously used in hi-tech devices. As a common feature of such devices one finds structures with dimensions in the order of the wavelength of the used light. To design and produce such devices, the wave nature of light must be taken into account. Accordingly, robust simulation tools are required which are based on rigorously solving Maxwell's equations, the governing equations of light propagation within macroscopic media. This thesis contributes to the modeling and the numerical computation of light scattering problems: Light scattering problems are typically posed on the entire space. The Perfectly-Matched -Layer method (PML) is widely used to restrict the simulation problem onto a bounded computational domain. We propose an adaptive PML method which exhibits a good convergence even for critical problems where standard PML implementations fail. Besides the computation of the near field, that is the electromagnetic field within the computational domain, it is of major interest to evaluate the electromagnetic field in the exterior domain and to compute the far field. So far, this was numerically only possible for simple geometries such as homogeneous exterior domains or layered media. To deal with more complicated devices, for example with waveguide inhomogeneities, we develop an evaluation formula based on the PML solution which allows for an exterior domain field evaluation in a half space above the device. Finally, we generalize the PML method to problems with multiply structured exterior domains. The term “multiply structured exterior domain” is defined in this thesis and means that the exterior domain exhibits several half-infinite structures. Mathematically, this gives rise to various complications. For example, no analytical solutions to Maxwell's equations for standard light sources are available in the exterior domain, which are needed to describe the incoming field in a light scattering problem. To tackle this we propose a new light scattering problem formulation which fits well into the PML method framework and which may be regarded as an extension of classical contributions by Sommerfeld, Wiener and Hopf. An exterior domain evaluation formula for multiply structured exterior domains with an extended illumination is derived as well.
    Keywords: ddc:510
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 3
    Publication Date: 2020-08-05
    Description: We introduce the coolest path problem, which is a mixture of two well-known problems from distinct mathematical fields. One of them is the shortest path problem from combinatorial optimization. The other is the heat conduction problem from the field of partial differential equations. Together, they make up a control problem, where some geometrical object traverses a digraph in an optimal way, with constraints on intermediate or the final state. We discuss some properties of the problem and present numerical solution techniques. We demonstrate that the problem can be formulated as a linear mixed-integer program. Numerical solutions can thus be achieved within one hour for instances with up to 70 nodes in the graph.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 4
    Publication Date: 2021-08-05
    Description: Given a general mixed integer program (MIP), we automatically detect block structures in the constraint matrix together with the coupling by capacity constraints arising from multi-commodity-flow formulations. We identify the underlying graph and generate cutting planes based on cuts in the detected network. Our implementation adds a separator to the branch-and-cut libraries of SCIP and CPLEX. We make use of the complemented mixed integer rounding framework (cMIR) but provide a special purpose aggregation heuristic that exploits the network structure. Our separation scheme speeds-up the computation for a large set of MIPs coming from network design problems by a factor of two on average.
    Keywords: ddc:510
    Language: English
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  • 5
    Publication Date: 2022-03-14
    Description: Pseudo-Boolean problems lie on the border between satisfiability problems, constraint programming, and integer programming. In particular, nonlinear constraints in pseudo-Boolean optimization can be handled by methods arising in these different fields: One can either linearize them and work on a linear programming relaxation or one can treat them directly by propagation. In this paper, we investigate the individual strengths of these approaches and compare their computational performance. Furthermore, we integrate these techniques into a branch-and-cut-and-propagate framework, resulting in an efficient nonlinear pseudo-Boolean solver.
    Keywords: ddc:510
    Language: English
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  • 6
    Publication Date: 2020-08-05
    Description: Every day, millions of people are transported by buses, trains, and airplanes in Germany. Public transit (PT) is of major importance for the quality of life of individuals as well as the productivity of entire regions. Quality and efficiency of PT systems depend on the political framework (state-run, market oriented) and the suitability of the infrastructure (railway tracks, airport locations), the existing level of service (timetable, flight schedule), the use of adequate technologies (information, control, and booking systems), and the best possible deployment of equipment and resources (energy, vehicles, crews). The decision, planning, and optimization problems arising in this context are often gigantic and “scream” for mathematical support because of their complexity. This article sketches the state and the relevance of mathematics in planning and operating public transit, describes today’s challenges, and suggests a number of innovative actions. The current contribution of mathematics to public transit is — depending on the transportation mode — of varying depth. Air traffic is already well supported by mathematics. Bus traffic made significant advances in recent years, while rail traffic still bears significant opportunities for improvements. In all areas of public transit, the existing potentials are far from being exhausted. For some PT problems, such as vehicle and crew scheduling in bus and air traffic, excellent mathematical tools are not only available, but used in many places. In other areas, such as rolling stock rostering in rail traffic, the performance of the existing mathematical algorithms is not yet sufficient. Some topics are essentially untouched from a mathematical point of view; e.g., there are (except for air traffic) no network design or fare planning models of practical relevance. PT infrastructure construction is essentially devoid of mathematics, even though enormous capital investments are made in this area. These problems lead to questions that can only be tackled by engineers, economists, politicians, and mathematicians in a joint effort. Among other things, the authors propose to investigate two specific topics, which can be addressed at short notice, are of fundamental importance not only for the area of traffic planning, should lead to a significant improvement in the collaboration of all involved parties, and, if successful, will be of real value for companies and customers: • discrete optimal control: real-time re-planning of traffic systems in case of disruptions, • model integration: service design in bus and rail traffic. Work on these topics in interdisciplinary research projects could be funded by the German ministry of research and education (BMBF), the German ministry of economics (BMWi), or the German science foundation (DFG).
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 7
    Publication Date: 2020-08-05
    Description: The steel mill slab design problem from the CSPLib is a binpacking problem that is motivated by an application of the steel industry and that has been widely studied in the constraint programming community. Recently, several people proposed new models and methods to solve this problem. A steel mill slab library was created which contains 380 instances. A closely related binpacking problem called multiple knapsack problem with color constraints, originated from the same industrial problem, were discussed in the integer programming community. In particular, a simple integer programming for this problem has been given by Forrest et al. [3]. The aim of this paper is to bring these different studies together. Moreover, we adopt the model of [3] for the steel mill slab problem. Using a state of the art integer program solver, this model is capable to solve all instances of the steel mill slab library, mostly in less than one second, to optimality. We improved, thereby, the solution value of 76 instances.
    Keywords: ddc:510
    Language: English
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  • 8
    Publication Date: 2020-08-05
    Description: Nowadays most data networks use shortest path protocols such as OSPF or IS-IS to route traffic. Given administrative routing lengths for the links of a network, all data packets are sent along shortest paths with respect to these lengths from their source to their destination. One of the most fundamental problems in planning shortest path networks is to decide whether a given set of routing paths forms a valid routing and, if this is not the case, to find a small subset of the given paths that cannot be shortest paths simultaneously for any routing lengths. In this paper we show that it is NP-hard to approximate the size of the smallest shortest path conflict by a factor less than 7/6.
    Keywords: ddc:510
    Language: English
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  • 9
    Publication Date: 2020-08-05
    Description: The Vehicle Positioning Problem (VPP) consists of the assignment of vehicles (buses, trams or trains) of a public transport or railway company to parking positions in a depot and to timetabled trips. Such companies have many different types of vehicles, and each trip can be performed only by vehicles of some of these types. These assignments are non-trivial due to the topology of depots. The parking positions are organized in tracks, which work as one- or two-sided stacks or queues. If a required type of vehicle is not available in the front of any track, shunting movements must be performed in order to change vehicles' positions, which is undesirable and should be avoided. In this text we present integer linear and non-linear programming formulations for some versions of the problem and compare them from a theoretical and a computational point of view.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 10
    Publication Date: 2020-03-11
    Description: The understanding of geometric structures and dynamical properties of molecular conformations gives insight into molecular long-term behavior. The identification of metastable conformations together with their life times and transition patterns is the intention of conformation dynamics. Conformation dynamics is a multi-scale approach that leads to a reduced description of the dynamical system in terms of a stochastic transition probability matrix. The present thesis deals with the error analysis of computed matrices and the resulting matrix functions. Since conformational membership vectors, as they are computed by the Robust Perron Cluster Analysis (PCCA+), form an invariant subspace of the transition matrix, subspace-based error estimators are of particular interest. The decomposition of the state space into basis functions and the approximation of integrals by Monte-Carlo quadrature give rise to row-wise correlated random matrices, for which stochastic norms are computed. Together with an appropriate statistical model for the distribution of matrix rows, this allows for the calculation of error bounds and error distributions of the invariant subspace and other variables of interest. Equilibration of errors among the basis functions can be achieved by enhanced sampling in regions where the trajectories are mixing slowly. Hierarchical refinement of such basis functions systematically improves the clustering into metastable conformations by reducing the error in the corresponding invariant subspace. These techniques allow for an evaluation of simulation results and pave the way for the analysis of larger molecules. Moreover, the extension of PCCA+ to non-reversible Markov chains, verified by the corresponding perturbation theory, and the modification of the objective function for the case of soft membership vectors represent a further generalization of the clustering method, thus continuing the development from PCCA over PCCA+ to PCCA++. The methods developed in this thesis are useful for but not limited to conformation dynamics. In fact, they are applicable to a broader class of problems which combine domain decomposition with Monte-Carlo quadrature. Possible application areas may include the chemical master equation or quantum dynamical systems.
    Description: Das Verständnis von geometrischen Strukturen und dynamischen Eigenschaften molekularer Konformationen ist essentiell für die Vorhersage des Langzeitverhaltens von Molekülen. Die Identifikation metastabiler Konformationen sowie die Bestimmung von Übergangswahrscheinlichkeiten und Haltezeiten sind Bestandteil der Konformationdynamik. Dabei handelt es sich um eine Mehrskalenmethode, die auf eine reduzierte Beschreibung des Systems mittels einer stochastischen Übergangsmatrix führt. In der vorliegenden Dissertation wurde untersucht, wie man die Genauigkeit der Matrizen sowie der daraus berechneten Größen quantifizieren kann. Im Mittelpunkt stehen dabei Fehlerschätzer für den invarianten Unterraum, da die rechten Eigenvektoren als Grundlage der Robusten Perron Cluster Analyse (PCCA+) zur Identifizierung der metastabilen Konformationen dienen. Die Zerlegung des Zustandsraumes in Basisfunktionen sowie die Approximation der Matrixeinträge mittels Monte-Carlo-Quadratur führen zu zeilenweise korrelierten Zufallsmatrizen. Mit Hilfe einer stochastischen Norm sowie einem geeigneten statistischen Modell für die Verteilung der Matrixzeilen können u.a. Fehlerschranken und -verteilungen für den invarianten Unterraum brechnet werden. Eine Equilibrierung des Fehlers zwischen den Basisfunktionen kann durch erweitertes Sampling in solchen Regionen erreicht werden, in denen die Trajektorien nur langsam mischen.Eine hierarchische Zerlegung dieser Basisfunktionen verbessert systematisch die Zerlegung in metastabile Konformationen, indem sie den Fehler im invarianten Unterraum reduziert. Diese Techniken gestatten eine Evaluierung der Simulationsergebnisse und ebnen den Weg zur Behandlung komplexerer Moleküle. Desweiteren wurden Verallgemeinerungen der PCCA+ untersucht. Die Erweiterung der PCCA+ auf nicht-reversible Markov-Ketten sowie die Modifizierung der Zielfunktion für den Fall der weichen Clusterung setzen die Entwicklung von der PCCA über PCCA+ zu PCCA++ fort. Somit können neue Anwendungsfelder für dieses Cluster-Verfahren erschlossen werden. Die Methoden wurden zwar in Rahmen der Konformationsdynamik entwickelt, jedoch lassen sie sich auf eine weite Problemklasse anwenden, in der Gebietszerlegungsverfahren mit Monte-Carlo-Quadratur kombiniert werden. Mögliche Anwendungsgebiete umfassen die chemische Master-Gleichung oder quantenchemische Systeme.
    Keywords: ddc:510
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 11
    Publication Date: 2020-08-05
    Description: The Vehicle Positioning Problem (VPP) is a classical combinatorial optimization problem in public transport planning. A number of models and approaches have been suggested in the literature, which work for small problems, but not for large ones. We propose in this article a novel set partitioning model and an associated column generation solution approach for the VPP. The model provides a tight linear description of the problem. The pricing problem, and hence the LP relaxation itself, can be solved in polynomial resp. pseudo-polynomial time for some versions of the problems.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 12
    Publication Date: 2020-08-05
    Description: Since the initial application of mathematical optimisation methods to mine planning in 1965, the Lerchs-Grossmann algorithm for computing the ultimate pit limit, operations researchers have worked on a variety of challenging problems in the area of open pit mining. This thesis focuses on the open pit mining production scheduling problem: Given the discretisation of an orebody as a block model, determine the sequence in which the blocks should be removed from the pit, over the lifespan of the mine, such that the net present value of the mining operation is maximised. In practise, when some material has been removed from the pit, it must be processed further in order to extract the valuable elements contained therein. If the concentration of valuable elements is not sufficiently high, the material is discarded as waste or stockpiled. Realistically-sized block models can contain hundreds of thousands of blocks. A common approach to render these problem instances computationally tractable is the aggregation of blocks to larger scheduling units. The thrust of this thesis is the investigation of a new mixed-integer programming formulation for the open pit mining production scheduling problem, which allows for processing decisions to be made at block level, while the actual mining schedule is still computed at aggregate level. A drawback of this model in its full form is the large number of additional variables needed to model the processing decisions. One main result of this thesis shows how these processing variables can be aggregated efficiently to reduce the problem size significantly, while practically incurring no loss in net present value. The second focus is on the application of lagrangean relaxation to the resource constraints. Using a result of Möhring et al. (2003) for project scheduling, the lagrangean relaxation can be solved efficiently via minimum cut computations in a weighted digraph. Experiments with a bundle algorithm implementation by Helmberg showed how the lagrangean dual can be solved within a small fraction of the time required by standard linear programming algorithms, while yielding practically the same dual bound. Finally, several problem-specific heuristics are presented together with computational results: two greedy sub-MIP start heuristics and a large neighbourhood search heuristic. A combination of a lagrangean-based start heuristic followed by a large neighbourhood search proved to be effective in generating solutions with objective values within a 0.05% gap of the optimum.
    Keywords: ddc:510
    Language: English
    Type: masterthesis , doc-type:masterThesis
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  • 13
    Publication Date: 2019-01-29
    Description: In dieser Arbeit wird ein neuer Ansatz zur Modellierung von thermal signifikanten Gefäßsträngen im Hyperthermie-Kontext betrachtet. Ausgehend von einer Konvektions-Diffusions-Gleichung wird durch Reskalierung des Massenflussterms eine Reduktion des Adergebietes auf eine 1D-Struktur erreicht. Nach numerischen Vorbetrachtungen wird die Grenzgleichung innerhalb einer verallgemeinerten Sobolev-Algebra formuliert. Die Untersuchung der Lösungsfamilie in klassischen Funktionenräumen zeigt, dass deren schwacher Grenzwert die Lösung der korrespondierenden Diffusions-Gleichung ist. Die Diskretisierung einer formalen Grenzgleichung mit Linienstromanteil stellt jedoch eine gute Approximation an die Diskretisierung des ursprünglichen Problems dar, wenn man die lokale Maschenweite an die Gefäßradien koppelt und bei erhöhtem Genauigkeitsbedarf auf ein vollständiges 3D-Modell umschaltet.
    Keywords: ddc:510
    Language: German
    Type: masterthesis , doc-type:masterThesis
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  • 14
    Publication Date: 2022-03-14
    Description: We present Undercover, a primal heuristic for mixed-integer nonlinear programming (MINLP). The heuristic constructs a mixed-integer linear subproblem (sub-MIP) of a given MINLP by fixing a subset of the variables. We solve a set covering problem to identify a minimal set of variables which need to be fixed in order to linearise each constraint. Subsequently, these variables are fixed to approximate values, e.g. obtained from a linear outer approximation. The resulting sub-MIP is solved by a mixed-integer linear programming solver. Each feasible solution of the sub-MIP corresponds to a feasible solution of the original problem. Although general in nature, the heuristic seems most promising for mixed-integer quadratically constrained programmes (MIQCPs). We present computational results on a general test set of MIQCPs selected from the MINLPLib.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 15
    Publication Date: 2020-08-05
    Description: We consider a system with Poisson arrivals and i.i.d. service times. The requests are served according to the state-dependent processor sharing discipline, where each request receives a service capacity which depends on the actual number of requests in the system. The linear systems of PDEs describing the residual and attained sojourn times coincide for this system, which provides time reversibility including sojourn times for this system, and their minimal non negative solution gives the LST of the sojourn time $V(\tau)$ of a request with required service time $\tau$. For the case that the service time distribution is exponential in a neighborhood of zero, we derive a linear system of ODEs, whose minimal non negative solution gives the LST of $V(\tau)$, and which yields linear systems of ODEs for the moments of $V(\tau)$ in the considered neighborhood of zero. Numerical results are presented for the variance of $V(\tau)$. In case of an M/GI/2-PS system, the LST of $V(\tau)$ is given in terms of the solution of a convolution equation in the considered neighborhood of zero. For bounded from below service times, surprisingly simple expressions for the LST and variance of $V(\tau)$ in this neighborhood of zero are derived, which yield in particular the LST and variance of $V(\tau)$ in M/D/2-PS.
    Keywords: ddc:510
    Language: English
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  • 16
    Publication Date: 2020-12-11
    Description: Eigentlich war der erste Autor nur zu einem Grußwort zur Tagung „GML² 2009 - Grundfragen Multi¬medialen Lehrens und Lernens“ eingeladen. Daraus wurde ein E-Learning-bezogener Vortrag, der – basierend auf Erfahrungen im Fach Mathematik – einen kritischen Blick auf die E-Learning-Szene in Deutschland wirft und diese mit entsprechenden Aktivitäten weltweit vergleicht. Dies ist die in seinen mathematischen Teilen gekürzte, in den E-Learning-Anteilen ein wenig erweiterte schriftliche Fassung des Vortrags. Der Artikel stammt nicht von E-Learning-Spezialisten sondern von Personen, die sich seit fast zwanzig Jahren mit elektronischer Information und Kommunikation (kurz: IuK) – insbesondere in der Mathematik – beschäftigen. Nach einer Definition von Michael Kerres kennzeichnet der Begriff E-Learning (electronic learning – elektronisch unterstütztes Lernen) alle Formen von Lernen, bei denen digitale Medien für die Präsentation und Distribution von Lernmaterialien und/oder zur Unterstützung zwischenmenschlicher Kommunikation zum Einsatz kommen, siehe z.B. http://de.wikipedia.org/wiki/E-Learning. IuK und E-Learning haben nach dieser Begriffsbildung viele Berührungspunkte. Deswegen wagen wir es, unsere positiven und negativen Erfahrungen im Bereich IuK in diesem Eröffnungsvortrag zu berichten, einige Entwicklungslinien zu vergleichen und eine eigene Kurzversion der Definition von E-Learning (besser E-Teaching and -Learning) voranzustellen: „Lehren und Lernen mit Unterstützung elektronischer Hilfsmittel“.
    Keywords: ddc:510
    Language: German
    Type: reportzib , doc-type:preprint
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  • 17
    Publication Date: 2020-08-05
    Description: Telecommunication transport networks consist of a stack of technologically different subnetworks, so-called layers, which are strongly interdependent. For example, one layer may correspond to an Internet (IP) backbone network whose links are realized by lightpath connections in an underlying optical fiber layer. To ensure that the network can fulfill its task of routing all communication requests, the inter-layer dependencies have to be taken into account already in the planning phase of the network. This is particularly important with survivability constraints, where connections in one layer have to be protected against cable cuts or equipment failures in another layer. The traditional sequential planning approach where one layer is optimized after the other cannot properly take care of the inter-layer dependencies; this can only be achieved with an integrated planning of several network layers at the same time. This thesis provides mathematical models and algorithmic techniques for the integrated optimization of two network layers with survivability constraints. We describe a multi-layer network design problem which occurs in various technologies, and model it mathematically using mixed-integer programming (MIP) formulations. The presented models cover many important practical side constraints from different technological contexts. In contrast to previous models from the literature, they can be used to design large two-layer networks with survivability requirements. We discuss modeling alternatives for various aspects of a multi-layer network and compare different routing formulations under multi-layer survivability constraints. We solve our models using a branch-and-cut-and-price approach with various problemspecific enhancements. This includes a presolving technique based on linear programming to reduce the problem size, combinatorial and sub-MIP-based primal heuristics to compute feasible network configurations, cutting planes which take the multi-layer survivability constraints into account to improve the lower bound on the optimal network cost, and column generation to generate flow variables dynamically during the algorithm. We develop techniques to speed up computations in a Benders decomposition approach and compare this approach to the standard formulation with a single MIP. We use the developed techniques to design large survivable two-layer networks by means of linear and integer programming methods. On realistic test instances with up to 67 network nodes and survivability constraints, we investigate the algorithmic impact of our techniques and show how to use them to compute good network configurations with quality guarantees. Most of the smaller test instances with up to 17 nodes can be solved to near-optimality. Moreover, we can compute feasible solutions and dual bounds even for large networks with survivability constraints, which has not been possible before.
    Keywords: ddc:510
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 18
    Publication Date: 2020-08-05
    Description: In the simplex algorithm, solving linear systems with the basis matrix and its transpose accounts for a large part of the total computation time. We investigate various methods from modern numerical linear algebra to improve the computation speed of the basis updates arising in LPs. The experiments are executed on a large real-world test set. The most widely used solution technique is sparse LU factorization, paired with an updating scheme that allows to use the factors over several iterations. Clearly, small number of fill-in elements in the LU factors is critical for the overall performance. Using a wide range of LPs we show numerically that after a simple permutation the non-triangular part of the basis matrix is so small, that the whole matrix can be factorized with (relative) fill-in close to the optimum. This permutation has been exploited by simplex practitioners for many years. But to our knowledge no systematic numerical study has been published that demonstrates the effective reduction to a surprisingly small non-triangular problem, even for large scale LPs. For the factorization of the non-triangular part most existing simplex codes use some variant of dynamic Markowitz pivoting, which originated in the late 1950s. We also show numerically that, in terms of fill-in and in the simplex context, dynamic Markowitz is quite consistently superior to other, more recently developed techniques.
    Keywords: ddc:510
    Language: English
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  • 19
    Publication Date: 2020-03-11
    Description: We compute expectation values for the solution of the nuclear Schrödinger equation. The proposed particle method consists of three steps: sampling of the initial Wigner function, classical transport of the sampling points, weighted phase space summation for the final computation of the expectation values. The Egorov theorem guarantees that the algorithm is second order accurate with respect to the semiclassical parameter. We present numerical experiments for a two-dimensional torsional potential with three different sets of initial data and for a six-dimensional Henon-Heiles potential. By construction, the computing times scale linearly with the number of initial sampling points and range between three seconds and one hour.
    Keywords: ddc:510
    Language: English
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  • 20
    Publication Date: 2022-03-14
    Description: This paper discusses how to build a solver for mixed integer quadratically constrained programs (MIQCPs) by extending a framework for constraint integer programming (CIP). The advantage of this approach is that we can utilize the full power of advanced MIP and CP technologies. In particular, this addresses the linear relaxation and the discrete components of the problem. For relaxation, we use an outer approximation generated by linearization of convex constraints and linear underestimation of nonconvex constraints. Further, we give an overview of the reformulation, separation, and propagation techniques that are used to handle the quadratic constraints efficiently. We implemented these methods in the branch-cut-and-price framework SCIP. Computational experiments indicates the potential of the approach.
    Keywords: ddc:510
    Language: English
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  • 21
    Publication Date: 2016-06-09
    Description: Supercomputers can simulate complex molecular systems. However, there is a very large gap between the fastest oscillations of covalent bonds of a molecule and the time-scale of the dominant processes. In order to extract the dominant time-scales and to identify the dominant processes, a clustering of information is needed. This thesis shows that only the subspace-based Robust Perron Cluster Analysis (PCCA+) can solve this problem correctly by the construction of a Markov State Model. PCCA+ allows for time-extrapolation in molecular kinetics. This thesis shows the difference between molecular dynamics and molecular kinetics. Only in the molecular kinetics framework a definition of transition rates is possible. In this context, the existence of an infinitesimal generator of the dynamical processes is discussed. If the existence is assumed, the Theorem of Gauß can be applied in order to compute transition rates efficiently. Molecular dynamics, however, is not able to provide a suitable statistical basis for the determination of the transition pattern.
    Keywords: ddc:510
    Language: English
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  • 22
    Publication Date: 2020-08-05
    Description: We consider a system with Poisson arrivals and general service times, where the requests are served according to the State-Dependent Processor Sharing (SDPS) discipline (Cohen's generalized processor sharing discipline), where each request receives a service capacity which depends on the actual number of requests in the system. For this system, denoted by $M/GI/SDPS$, we derive approximations for the squared coefficients of variation of the conditional sojourn time of a request given its service time and of the unconditional sojourn time by means of two-moment fittings of the service times. The approximations are given in terms of the squared coefficients of variation of the conditional and unconditional sojourn time in related $M/D/SDPS$ and $M/M/SDPS$ systems, respectively. The numerical results presented for $M/GI/m-PS$ systems illustrate that the proposed approximations work well.
    Keywords: ddc:510
    Language: English
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  • 23
    Publication Date: 2020-08-05
    Description: We consider a system with Poisson arrivals and i.i.d. service times and where the requests are served according to the state-dependent (Cohen's generalized) processor sharing discipline, where each request in the system receives a service capacity which depends on the actual number of requests in the system. For this system we derive asymptotically tight upper bounds for the moments of the conditional sojourn time of a request with given required service time. The bounds generalize corresponding results, recently given for the single-server processor sharing system by Cheung et al. and for the state-dependent processor sharing system with exponential service times by the authors. Analogous results hold for the waiting times.
    Keywords: ddc:510
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  • 24
    Publication Date: 2020-11-13
    Description: The Dynamic Multi-Period Routing Problem DMPRP introduced by Angelelli et al. gives a model for a two-stage online-offline routing problem. At the beginning of each time period a set of customers becomes known. The customers need to be served either in the current time period or in the following. Postponed customers have to be served in the next time period. The decision whether to postpone a customer has to be done online. At the end of each time period, an optimal tour for the customers assigned to this period has to be computed and this computation can be done offline. The objective of the problem is to minimize the distance traveled over all planning periods assuming optimal routes for the customers selected in each period. We provide the first randomized online algorithms for the DMPRP which beat the known lower bounds for deterministic algorithms. For the special case of two planning periods we provide lower bounds on the competitive ratio of any randomized online algorithm against the oblivious adversary. We identify a randomized algorithm that achieves the optimal competitive ratio of $\frac{1+\sqrt{2}}{2}$ for two time periods on the real line. For three time periods, we give a randomized algorithm that is strictly better than any deterministic algorithm.
    Keywords: ddc:510
    Language: English
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  • 25
    Publication Date: 2021-08-05
    Description: This thesis introduces the novel paradigm of "constraint integer programming" (CIP), which integrates constraint programming (CP) and mixed integer programming (MIP) modeling and solving techniques. It is supplemented by the software SCIP, which is a solver and framework for constraint integer programming that also features SAT solving techniques. SCIP is freely available in source code for academic and non-commercial purposes. Our constraint integer programming approach is a generalization of MIP that allows for the inclusion of arbitrary constraints, as long as they turn into linear constraints on the continuous variables after all integer variables have been fixed. The constraints, may they be linear or more complex, are treated by any combination of CP and MIP techniques: the propagation of the domains by constraint specific algorithms, the generation of a linear relaxation and its solving by LP methods, and the strengthening of the LP by cutting plane separation. The current version of SCIP comes with all of the necessary components to solve mixed integer programs. In the thesis, we cover most of these ingredients and present extensive computational results to compare different variants for the individual building blocks of a MIP solver. We focus on the algorithms and their impact on the overall performance of the solver. In addition to mixed integer programming, the thesis deals with chip design verification, which is an important topic of electronic design automation. Chip manufacturers have to make sure that the logic design of a circuit conforms to the specification of the chip. Otherwise, the chip would show an erroneous behavior that may cause failures in the device where it is employed. An important subproblem of chip design verification is the property checking problem, which is to verify whether a circuit satisfies a specified property. We show how this problem can be modeled as constraint integer program and provide a number of problem-specific algorithms that exploit the structure of the individual constraints and the circuit as a whole. Another set of extensive computational benchmarks compares our CIP approach to the current state-of-the-art SAT methodology and documents the success of our method.
    Description: Diese Arbeit stellt einen integrierten Ansatz aus "Constraint Programming" (CP) und Gemischt-Ganzzahliger Programmierung ("Mixed Integer Programming", MIP) vor, den wir "Constraint Integer Programming" (CIP) nennen. Sowohl Modellierungs- als auch Lösungstechniken beider Felder fließen in den neuen integrierten Ansatz ein, um die unterschiedlichen Stärken der beiden Gebiete zu kombinieren. Als weiteren Beitrag stellen wir der wissenschaftlichen Gemeinschaft die Software SCIP zur Verfügung, die ein Framework für Constraint Integer Programming darstellt und zusätzlich Techniken des SAT-Lösens beinhaltet. SCIP ist im Source Code für akademische und nicht-kommerzielle Zwecke frei erhältlich. Unser Ansatz des Constraint Integer Programming ist eine Verallgemeinerung von MIP, die zusätzlich die Verwendung beliebiger Constraints erlaubt, solange sich diese durch lineare Bedingungen ausdrücken lassen falls alle ganzzahligen Variablen auf feste Werte eingestellt sind. Die Constraints werden von einer beliebigen Kombination aus CP- und MIP-Techniken behandelt. Dies beinhaltet insbesondere die "Domain Propagation", die Relaxierung der Constraints durch lineare Ungleichungen, sowie die Verstärkung der Relaxierung durch dynamisch generierte Schnittebenen. Die derzeitige Version von SCIP enthält alle Komponenten, die für das effiziente Lösen von Gemischt-Ganzzahligen Programmen benötigt werden. Die vorliegende Arbeit liefert eine ausführliche Beschreibung dieser Komponenten und bewertet verschiedene Varianten in Hinblick auf ihren Einfluß auf das Gesamt-Lösungsverhalten anhand von aufwendigen praktischen Experimenten. Dabei wird besonders auf die algorithmischen Aspekte eingegangen. Ein weiterer Hauptteil der Arbeit befasst sich mit der Chip-Design-Verifikation, die ein wichtiges Thema innerhalb des Fachgebiets der "Electronic Design Automation" darstellt. Chip-Hersteller müssen sicherstellen, dass der logische Entwurf einer Schaltung der gegebenen Spezifikation entspricht. Andernfalls würde der Chip fehlerhaftes Verhalten aufweisen, dass zu Fehlfunktionen innerhalb des Gerätes führen kann, in dem der Chip verwendet wird. Ein wichtiges Teilproblem in diesem Feld ist das Eigenschafts-Verifikations-Problem, bei dem geprüft wird, ob der gegebene Schaltkreisentwurf eine gewünschte Eigenschaft aufweist. Wir zeigen, wie dieses Problem als Constraint Integer Program modelliert werden kann und geben eine Reihe von problemspezifischen Algorithmen an, die die Struktur der einzelnen Constraints und der Gesamtschaltung ausnutzen. Testrechnungen auf Industrie-Beispielen vergleichen unseren Ansatz mit den bisher verwendeten SAT-Techniken und belegen den Erfolg unserer Methode.
    Keywords: ddc:510
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 26
    Publication Date: 2020-08-05
    Description: In this paper we investigate the fare planning model for public transport, which consists in designing a system of fares maximizing the revenue. We discuss a discrete choice model in which passengers choose between different travel alternatives to express the demand as a function of fares. Furthermore, we give a computational example for the city of Potsdam and discuss some theoretical aspects.
    Keywords: ddc:510
    Language: English
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  • 27
    Publication Date: 2020-08-05
    Description: This extended abstract is about algorithms for controlling elevator systems employing destination hall calls, i.e. the passenger provides his destination floor when calling an elevator. We present the first exact algorithm for controlling a group of elevators and report on simulation results indicating that destination hall call systems outperform conventional systems.
    Keywords: ddc:510
    Language: English
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  • 28
    Publication Date: 2019-01-29
    Description: The paper proposes goal-oriented error estimation and mesh refinement for optimal control problems with elliptic PDE constraints using the value of the reduced cost functional as quantity of interest. Error representation, hierarchical error estimators, and greedy-style error indicators are derived and compared to their counterparts when using the all-at-once cost functional as quantity of interest. Finally, the efficiency of the error estimator and generated meshes are demonstrated on numerical examples.
    Keywords: ddc:510
    Language: English
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  • 29
    Publication Date: 2016-06-09
    Description: The paper considers the time integration of frictionless dynamical contact problems between viscoelastic bodies in the frame of the Signorini condition. Among the numerical integrators, interest focuses on the contact-stabilized Newmark method recently suggested by Deuflhard et al., which is compared to the classical Newmark method and an improved energy dissipative version due to Kane et al. In the absence of contact, any such variant is equivalent to the Störmer-Verlet scheme, which is well-known to have consistency order 2. In the presence of contact, however, the classical approach to discretization errors would not show consistency at all because of the discontinuity at the contact. Surprisingly, the question of consistency in the constrained situation has not been solved yet. The present paper fills this gap by means of a novel proof technique using specific norms based on earlier perturbation results due to the authors. The corresponding estimation of the local discretization error requires the bounded total variation of the solution. The results have consequences for the construction of an adaptive timestep control, which will be worked out subsequently in a forthcoming paper.
    Keywords: ddc:510
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  • 30
    Publication Date: 2020-08-05
    Description: The mathematical treatment of planning problems in public transit has made significant advances in the last decade. Among others, the classical problems of vehicle and crew scheduling can nowadays be solved on a routine basis using combinatorial optimization methods. This is not yet the case for problems that pertain to the design of public transit networks, and for the problems of operations control that address the implementation of a schedule in the presence of disturbances. The article gives a sketch of the state and important developments in these areas, and it addresses important challenges. The vision is that mathematical tools of computer aided scheduling (CAS) will soon play a similar role in the design and operation of public transport systems as CAD systems in manufacturing.
    Description: Die mathematische Behandlung von Planungsproblemen im öffentlichen Verkehr hat im letzten Jahrzehnt große Fortschritte gemacht. Klassische Probleme wie die Umlauf- und die Dienstplanung können heutzutage routinemäßig mit kombinatorischen Optimierungsmethoden gelöst werden. Die Behandlung von Problemen der Angebotsplanung und der Betriebssteuerung sind dagegen noch nicht ganz auf diesem Stand. Dieser Artikel gibt einen Überblick über den Stand der Forschung, über wichtige Entwicklungen und einige Herausforderungen in diesem Gebiet. Die Vision ist, dass mathematische Planungswerkzeuge im öffentlichen Verkehr (Computer Aided Scheduling, CAS) in Zukunft eine ähnliche Rolle spielen werden wie CAD-Systeme in der industriellen Fertigung.
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  • 31
    Publication Date: 2022-07-19
    Description: The reconstruction of geometric shapes plays an important role in many biomedical applications. One example is the patient-specific, computer-aided planning of complex interventions, which requires the generation of explicitly represented geometric models of anatomical structures from medical image data. Only solutions that require minimal interaction by medical personnel are likely to enter clinical routine. Another example is the planning of surgical corrections of deformities where the target shape is unknown. Surgeons are often forced to resort to subjective criteria. These applications still pose highly challenging reconstruction problems, which are addressed in this thesis. The fundamental hypothesis, pursued in this thesis, is that the problems can be solved by incorporating a-priori knowledge about shape and other application-specific characteristics. Here, we focus mainly on the aspect of geometric shape analysis. The basic idea is to capture the most essential variations of a certain class of geometric objects via statistical shape models, which model typical features contained in a given population, and restrict the outcome of a reconstruction algorithm (more or less) to the space spanned by such models. A fundamental prerequisite for performing statistical shape analysis on a set of different objects is the identification of corresponding points on their associated surfaces. This problem is particularly difficult to solve if the shapes stem from different individuals. The reason lies in the basic difficulty of defining suitable measures of similarity. In this thesis, we divide the correspondence problem into feature and non-feature matching. The feature part depends on the application, while the non-feature part can be characterized by a purely geometric description. We propose two different approaches. The first approach has proved useful in many applications. Yet, it suffers from some practical limitations and does not yield a measure of similarity. Our second, variational, approach is designed to overcome these limitations. In it, we propose to minimize an invariant stretching measure, constrained by previously computed features. An important property, which sets our method apart from previous work, is that it does not require the computation of a global surface parameterization.
    Keywords: ddc:510
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 32
    ISSN: 1434-601X
    Keywords: 27.80.+w 190 ⩽ A ⩽ 219 ; 25.40.-h Nucleon-induced reactions ; 25.40.Sc Spallation reactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Neutrons and light charged particles produced in 62.9MeV proton-induced reactions on 208Pb were measured during a single experiment performed at the CYCLONE facility in Louvain-la-Neuve (Belgium). Two independent experimental set-ups were used to extract double differential cross-sections for neutrons, protons, deuterons, tritons, 3He and alpha-particles. Charged particles were detected using a set of Si- Si- CsI telescopes from 25° to 155°, by step of 10 degrees. Neutrons were measured using shielded DeMoN counters, liquid NE213 scintillators, at 24°, 35°, 55°, 80° and 120°. These data allowed the determination of angle differential, energy differential and total production cross-sections. A comparison with theoretical calculations (MCNPX, FLUKA and TALYS) has been performed. It shows that the neutron and proton production rates are well predicted by MCNPX, using the INCL4 option. All the other codes underestimate the neutron production whereas they overestimate the proton one. For composite particles, which represent 17% of the charged particle total reaction cross-section, neither the shape nor the amplitude of the cross-sections are correctly predicted by the models.
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  • 33
    ISSN: 1434-601X
    Keywords: 29.30.Kv X- and γ-ray spectroscopy ; 23.20.Lv γ transitions and level energies ; 21.60.Ev Collective models ; 27.80.+w 190 ⩽ A ⩽ 219
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Excited states in 191Pt have been populated using the reaction 186W + 11B at 85MeV beam energy. Gamma-ray coincidences were measured using the EUROGAM-II spectrometer array. The level scheme has been extended considerably. Evidence for favoured structures of highly triaxial shape with γ ∼ -90° coexisting with oblate structures has been obtained by comparison with total Routhian surface and cranked shell model calculations. The presence of proton excitations in both positive- and negative-parity states has been confirmed.
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  • 34
    Publication Date: 2022-07-19
    Description: Multi-scale phenomena are abundant in many application fields. Representing and numerically simulating such processes is a challenging task since quite different scales have to be resolved, which often requires enormous amounts of storage and computational power. An important strategy in this context is adaptivity, i.e. local adjustment of the spatio-temporal resolution to the details to be resolved. A standard representation therefore are hierarchical, locally refined grids. A specific adaptive approach for solving partial differential equations, usually called AMR (Adaptive Mesh Refinement), was introduced in 1984. The basic idea is to combine the simplicity of structured grids and the advantages of local refinement. In this numerical scheme the computations are started on a set of coarse, potentially overlapping structured grids, that cover the computational domain. Local error criteria are applied to detect regions that require higher resolution. These are covered by subgrids with decreasing mesh spacing, which do not replace, but rather overlap the refined regions of the coarser patches. The equations are advanced on the finer subgrids and the refinement procedure recursively continues until all cells fulfill the considered error criteria, giving rise to a hierarchy of nested levels of refinement. In 1989 a variant of this scheme, called Structured Adaptive Mesh Refinement (SAMR), which reduces some of the complexity of the original approach, was proposed. While the separate subgrids in the AMR scheme could be rotated against each other, in SAMR they are aligned with the major axes of the coordinate system, which for example simplifies the computation of fluxes of (conserved) quantities through the cell faces. SAMR has become more and more popular in the last decade, and nowadays it is applied in many domains like hydrodynamics, meteorology and in particular in cosmology and relativistic astrophysics. Due to this growing popularity, an increasing number of scientists is in need of appropriate interactive visualization techniques to interpret and analyze AMR simulation data. Tools for both, 2D analysis to quantitatively convey the information within single slices and 3D representations to apprehend the overall structure are required. In this thesis we develop direct and indirect volume visualization algorithms for scalar fields that are defined on structured Adaptive Mesh Refinement (SAMR) grids. In particular algorithms for planar slicing and the display of height fields, C0-continuous isosurface extraction, software-, and hardware-based direct volume rendering and temporal interpolation for cell-, and vertex-centered data on unrestricted SAMR grids are proposed. Additionally we investigate the applicability of SAMR data structures for accelerated software-, and hardware-based volume rendering of large 3D scalar data.
    Keywords: ddc:510
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 35
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: By means of the ‘intravitam technic’ developed by Baumgartner and Payne (1931), the mature or maturing sperm of Chortophaga viridifasciata have been traced from the follicle of the testes in the male to the locus of fertilization in the female. The sperm aggregated into bundles, and held tight by a hyaline cytoplasmic cap, spiral up the follicle, turn and spiral back to the vas deferens by means of a periodic lashing and writhing of the sperm tails.The genital tract is described briefly. In the vasa deferentia and storage tubules, the sperm bundles are usually in a quiescent state, having been inactivated most probably by secretions from the tubules.Peristalsis and currents in the fluid contents of the tubules move the inactivated sperm from the vesicles of the male to the seminal receptacle of the female, where the cytoplasmic caps gradually disintegrate. This permits individual sperm to pass down the seminal duct and fertilize the ovum just before oviposition.Single photomicrographs and a series of photomicrographs show the sperm in various parts of the genital system and making actual progress up a follicle. A stained preparation was used for only one of the photos. The other nineteen are from living unstained tissue. The intravitam observations are, most probably, more ‘vital’ than any heretofore recorded.
    Additional Material: 3 Ill.
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  • 36
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 54 (1933) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 37
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This investigation was undertaken to determine some of the variables involved in the demonstration of the Golgi elements. Gland cells of vertebrates were studied vitally, after impregnation by osmic acid methods, and after autolysis.The duration of the staining period and the concentration of the stain condition the results obtained by vital staining with neutral red. The success of impregnation of Golgi elements with osmic acid varies with,(1) the type of tissue, (2) the time of initial fixation in relation to the time of the death of the animal, (3) the position of the cell in the piece of tissue, and, (4) the temperature of incubation with osmic acid. Stages in the impregnation of Golgi elements can be followed by examining preparations of the same tissue at frequent intervals during the incubation period. An increase in the amount of material which reduces osmic acid and which may form Golgi elements occurs in the cells during autolysis.The results are interpreted as indicating that Golgi elements are visible products of chemical reactions that occur in cells. They represent localized regions containing particular classes of chemical compounds which may be present, as such, in living cells or result from transformations in the cells during incubation. It is suggested that for the cells under consideration these substances may be unsaturated fatty acids.
    Additional Material: 1 Ill.
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  • 38
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 54 (1933), S. 399-413 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The m. trapezius, with both brachial and branchial functions, is in seeming series with the mm. interarcuales laterales. The intrinsic muscles of the fin occur as a dorsal extensor sheet and three (or four) ventral flexor components. The spinal nerves, uncomplicated by extensive anastomoses, which supply the fin, clearly show that in the dogfish the fin muscles are derived not from dorsal and ventral elements, but from anterior and posterior, or protractor and retractor elements. The nerves prove that from the original protractor musculature only the anterior portion of the present flexor group is derived, while the original retractor musculature has become all of the extensor and the posterior part of the flexor series. Faradic stimulation of the live animal is satisfactory, although there is much variation in the sensitivity, particularly of different muscles.
    Additional Material: 4 Ill.
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  • 39
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 54 (1933), S. 477-491 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mitochondria in the male germ cells of Sciara exhibit peculiarities as regards both morphological characteristics and distribution. In form. they show superficial similarity with those of some of the scorpions, while their distribution may be peculiar to the genus and depend on unusual meiotic divisions.
    Additional Material: 4 Ill.
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  • 40
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 54 (1933), S. 459-475 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A description of the urogenital system in both sexes of Lepidosteus platystomus Rafinesque, and new observations on the blood supply to this system as well as to the rest of the viscera is given.The testes resemble the true piscine type. The sperm are carried by numerous vasa efferentia to the kidney tubules, through the mesonephros to the wolffian duct, and to the exterior as in the elasmobranchs and amphibians. The most anterior of the vasa efferentia are non-functional. The ovaries are simple sac-like structures continuous with their ducts. The oviducts transverse the ventro-lateral surface of the mesonephros, and enter into the dilated portions of the wolffian ducts, where they join, directly anterior to the urogenital aperture. There are no ducts in the male homologous with the oviducts of the female. The kidneys fused posteriorly, appear to extend the entire length of the body cavity, but the anterior third is non-urinary.By injection methods, the celiaco-mesenteric artery is shown to be crowded to the posterior end of the body cavity by the complicated swim-bladder, and runs anteriorly to supply the entire viscera. Its anterior portion is incorporated in the liver.
    Additional Material: 5 Ill.
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  • 41
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1933) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 42
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1933), S. 29-51 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This article is an account of the complete musculature of an adult Neuropteran insect, Chrysopa plorabunda. Previous anatomical discussions on this order of insects include only a few of the muscles of the head and thoracic regions, while those of the abdomen are entirely lacking. The muscles here described include those of the head, thorax, and abdomen. The origin, insertion, and function of each muscle is given. The boundaries of several of the sclerites, especially those of the labium, are located by the observations on the musculature of these parts. The meso- and metathoracic wings are of the same size and for that reason the muscles of these regions are very much alike. The prothorax is greatly elonated, causing the muscles of that region to differ to a greater or less degree from the ‘general rule’ in insects. The abdominal muscles may be arranged in the several groups generally found in insects. In several cases, however, both the origin and insertion of the muscle have been shifted to accompany changes which have taken place in the abdominal segmentation. All of the muscles are shown in the four plates containing nineteen figures which accompany the text.
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  • 43
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1933), S. 131-135 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Photomicrographs have been made of grasshopper spermatocytes using ultraviolet light of several wave lengths. For studying chromosomes this wave length should be between ca 2800 A and ca 2500 A. With higher frequencies the entire cell becomes strongly absorbing and relatively little detail is to be seen. All cell structures, including the chromosomes, are as transparent to λ = 3500 A and to longer ultraviolet waves as they are to visible light. The present experiments do not indicate the exact point between λ = 3500 A and λ = 2800 A at which the selective chromatin absorption commences.
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  • 44
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This investigation consists of an extensive histological study of a special strain of abnormal x-rayed mice, in an attempt to determine the embryonic origin and development of certain congenital abnormalities that are hereditary.The study shows that development of the x-rayed strain is normal up to the thirteenth day after insemination, after which pathological structures appear in the form of blebs, hematomas, and thrombi. As a result of the formation of the blebs and hematomas a general condition is set up within the embryo which resembles that of thrombosis. The thrombi when formed exert a mechanical effect by crowding out the normal tissue. A chemical effect is also produced by the blood cells and fluid extravasated from the thrombus which penetrate into the forming tissues resulting in their perverted development. Thus the thrombi are the immediate factors causing the various regions of the body to be deformed.
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  • 45
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    Journal of Morphology 55 (1933), S. 207-251 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The Goodeidae are a family of cyprinodonts containing about nine genera and twenty-six species. They are confined exclusively to the Mexican Plateau and to streams in the immediate vicinity. All are viviparous. Fertilization is internal. The eggs are extremely small and contain very little yolk. The embryos are retained in the ovarian follicles until the yolk is practically absorbed, in the meantime developing unique absorptive organs in the form of extensive ribbon-shaped proctodaeal processes. The embryos are evacuated into the intra-ovarian cavity where they are retained for several weeks, during which time the proctodaeal processes become extended. The ovary becomes a nutritive organ and produces secretions which are discharged into the intra-ovarian cavity and absorbed by the embryo through their unique processes. The processes differ in form, number, and histological structure, but are specific in their peculiarities for each species. These specific differences, together with marked differences in the ovary, will furnish a basis for a re-classification of the genera and species of the family. A comparison in made between this family and the other ovo-viviparous and viviparous cyprinodonts, on the basis of which it is concluded that the Goodeidae have arisen separately from an ovo-viviparous ancestor, which in turn was derived from an ovo-viviparous type. A comparison is also made between the peculiarities of reproduction in this family and those of other viviparous teleosts.
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  • 46
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    Journal of Morphology 55 (1933), S. 349-385 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Lead poisoning causes a selective destruction of mature erythrocytes, thereby depleting the spleen and stimulating differentiation and proliferation of erythrocytes in the blood. In conjunction with splenectomy, this intravascular erythropoiesis is markedly accelerated.During the progressive anemia and subsequent regeneration of erythrocytes in simple lead poisoning the major hemopoietic loci, spleen, mesonephros, liver, and epicardium were observed. The spleen is most rapidly affected. The red cell progenitor first present in the circulation is the hemoblast, but later numerous lymphocytes enter the blood stream and are transformed into erythrocytes.Following simple splenectomy the blood shows relatively little change. A mild regenerative activity of both erythrocytes and thrombocytes ensues. In lead poisoning after splenectomy the blood picture resembles that of simple lead poisoning. The anemia is produced more rapidly and the regeneration of erythrocytes is delayed.This study emphasizes the importance of the blood stream of Necturus as a site of red cell differentiation and proliferation, and shows that the lymphocyte may be a possible progenitor of erythrocytes and thrombocytes. Under normal conditions the hemoblast suffices as a source for red cells, but under abnormal or experimental conditions, where the demand for new cells is excessive and prolonged, the lymphocyte plays a major role.
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  • 47
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 54 (1933), S. 233-258 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fundamental structure of the brain stem is uniform throughout the vertebrate series, not essentially because it expresses an architypical pattern, but because of the constancy of peripheral connections and their internal relationships, both of which are parts of an apparatus of adjustment to environment which is common to vertebrates. Other parts of the brain are more variable because, with complication of the behavior pattern in higher forms, more elaborate and diversified mechanisms of correlation and integration are requisite.The brain stem between the olfactory bulb and other primary sensory centers is plastic tissue not dominated by any single sensory-motor system; it is the meeting place of descending and ascending sensory paths. Here the chief apparatus of correlation and integration is elaborated. From it emerge the complex thalamic and cortical adjustors. The pallium is not a primary constituent of the vertebrate brain. The pallial type of organization gradually emerged from the more ancient subpallial type and comes to mature expression in the cerebral cortex. Several instructive stages in the progressive differentiation of cortical structure and connections are seen in the amphibian forebrain, but the process is not consummated. Amphibia have no cerebral cortex, though cortical primordia are evident here and in various fishes. Static concepts of architypes and the dialectic of ‘form-analytic’ argumentation are replaced by a more dynamic treatment of morphogenesis.
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  • 48
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    Journal of Morphology 54 (1933), S. 347-363 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: From a mating of first-cousins, of whom the female had cataract, there issued in four generations a progeny of 138 individuals, 33 of whom had cataract (23.8 per cent). Discounting the last generation, about which little is known, also discounting other unknown members, there were 29 known unaffected, 30 known affected, i.e., 50.8 per cent had cataract. The pedigree by generations shows that cataract is inherited as an autosomal (Mendelian) dominant. However, the mode of inheritance is atypical in that the defective gene for cataract may be borne, and is so borne because transmitted, without producing in the bearer its characteristic defect. In the second generation there were four of a family of nine with cataract; of the five without cataract two produced cataractous offspring and three did not marry. The literature is replete with pedigrees in which cataract is inherited as a typical autosomal dominant; there are a few pedigrees (four are reproduced) in which the mode of inheritance, while distinctly that of an autosomal dominant, resembles the present pedigree in being atypical. It is concluded that cataract is inherited as an autosomal dominant, but that in some cases it is produced only under certain conditions. These conditions are as yet not definitely known. Clinical writers seem to favor the view that nutritional and endocrine disturbances predispose to the realization of the defect.
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  • 49
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    Journal of Morphology 54 (1933), S. 365-388 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A histological study of Hammond's simple recessive ‘furless’ rabbits was made from many series of sections taken from the skin of both the normal and furless rabbits of several pertinent ages.It was found that the external absence of under-hair or fur exists because of a failure of the hairs of these follicles to erupt. This failure is due to a premature keratinization which first affects the sebaceous glands and then the inner epithelial sheath. The resulting abnormal channel allows an erratic escape, especially of the regenerating hair above the incomplete inner sheath into the surrounding connective tissue, where the escaped part of the hair atrophies. The final condition shows an inflammatory reaction in the areolar tissue here. There is no check on the growth from the bulb of the root. Other elements of the skin verify this excessive keratinization.The cause of the abnormal metabolic changes conceivably lies in an inadequate tissue supply of oxygen or nutrition. The regulator may be the sympathetic system directly or indirectly (by hormone action), or it may be an inhibitor resident in the integument itself.
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  • 50
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The anatomical isolation of the auricles from the ventricle in hearts of fresh-water mussels representing nine North American species has been confirmed. The muscle fibers in these hearts without exceptions were found to be of the smooth, unstriated type. Bundles of these fibers loosely interwoven, form the thin, delicate, heart wall, which contains many sinus-like spaces. The outside portion of the heart wall exposed to the pericardial fluid is covered with a definite epicardium composed of a single, dense layer of epithelial and scattering mucous cells. The inside of the heart cavity has no endocardium, the muscle fibers being in direct contact with the blood. No special conduction tissue, nerves or ganglia were found in the heart wall. Correlations of these anatomical and histological findings with the physiological reactions of the living heart in situ are made, and the mechanical and chemical control of the heart discussed.
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  • 51
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Observations of earlier workers concerning the limited region from which anterior regeneration will occur in Tubifex and the reduced number of segments formed were confirmed in control worms used in these experiments. Only three anterior segments are replaced when as many as twelve are removed. Regeneration is completed within 18 days.Removal of anterior segments from worms that have received 9000 (r) units exposure to x-rays is not followed by regeneration. The wound heals rapidly and worms have been kept in laboratory 70 days without further change. Longitudinal sect ons of injured ends show that the epidermis and muscle layers extend across the wound surface to completely close the body cavity. The intestine retracts slightly and heals to form a blind tube. No mitotic figures appear in cells of this region and there is no evidence of regeneration.In control worms material for formation of the cerebral ganglia and new epidermis arises by proliferation of epidermal cells. The new pharynx arises from the region of the old intestine adjacent to the wound surface. The muscle layers of the body wall and pharynx in new segments are apparently formed by migration of cells from the old muscle elements about the margin of the wound area. No neoblasts were observed in anterior migration or in the process of formation upon adjacent septa in any of the worms.
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  • 52
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    Journal of Morphology 54 (1933) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 53
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    Journal of Morphology 54 (1933), S. 429-449 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The rudimentary copulatory organ of chickens was first observed as a phallic knob in 6-day embryos. This phallic knob enlarged similarly in both male and female embryos up to the twelfth day: from the twelfth to the seventeenth day it was distinguished by a large process in the males and a diminishing process in the females. Further differentiation took place from the eighteenth to the twenty-first days: some females lacked the porcess, others retained a smaller process than that of the male. As growth advance, fewer females retained the process until at 12 weeks of age it had entirely disappeared. The process was found in all males and showed no retrogression, whereas the few capons examined lacked it. A ridge-shaped ‘pseudo’ process developed at about 1 week in some females and was present up to 3 weeks of age. Histologically and embryologically, the process was seen to possess some characteristics of a penis. The cloacal method of sex determination might be used with an average maximum accuracy of about 90 per cent in living day-old chicks.
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  • 54
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    Journal of Morphology 54 (1933), S. 521-547 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The sex cycles of a chimpanzee were studied for 18 months, during which the animal matured, menstruated four times, conceived, and delivered.Pronounced swelling of the ano-genital region appeared periodically prior to the first menstruation. During menstrual cycles the swelling endured during most of the period between flows. Genital swelling was always accompanied by estrus; copulation and insemination never occurred during its absence.The animal was alert and active when in estrus, demonstrated non-sexual affection for the male just prior to the flow, and appeared to be physically distressed during the first days of each flow.There were periodic weight changes coordinated with the animal's menstrual cycles.During pregnancy menstruation ceased, but genital swelling, with accompanying sexual receptivity, continued in irregular cycles.Cyclic changes in the desquamation of the vaginal epithelium occurred during menstrual cycles, were absent during pregnancy.The gestation period was approximately 246 days. At death from puerperal sepsis, 15 days after delivery, the ovaries were in a restin stage, one of them bearing a degenerating corpus luteum.The evidence given indicates that sex-skin swelling and estrus are similarly controlled, but may occur independently of menstruation, cornification of the vaginal epithelium, or ovulation.
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  • 55
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    Journal of Morphology 55 (1933), S. 1-13 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The molluscan genus Indoplanorbis is shown to differ markedly from all other members of the family Planorbidae in the generative complex, the vas deferens being encased in a long, flexible tube in which it is freely movable. The preputium of the male complex is shown to be completely evertible from the male opening and to act as a male copulatory organ. The presence of a single, heavy penial retractor innervated by an equally strong nerve is indicated. Comparisons are made with the genitalia of the European Coretus and the American Helisoma showing fundamental differences in the generative apparatus of the three groups. Indoplanorbis is most closely related to Coretus, the vas deferens of that group being also encased in a tube. Helisoma differs from both of these genera, the vas deferens not being encased in a tube and is of the same diameter throughout its length.
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  • 56
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    Journal of Morphology 55 (1933), S. 119-129 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The vascular channels and sinuses of this trematode contain three varieties of cells: eosinophilic granulocytes, primitive hemocytoblasts (‘amebocytes’), and modified hemocytoblasts. The latter suggest a specialized blood corpuscle, but represent apparently only a stage in the dissolution of intravascular hemocytoblasts. These ‘corpuscles’ have the form of flattened lenticular discs, approximately 12 μ in diameter. The eosinophils differentiate extravascularly from hemocytoblasts. The hemocytoblasts are in part free parenchymal cells, in part they arise from a bilaterally paired ‘lymphogenous organ’ or ‘blood island’ associated with the lateral vascular channels at the level where the ceca diverge from the esophagus.
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  • 57
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 30 Ill.
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  • 58
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Nyctotherus cordiformis and Opalinids infesting Rana pipiens were studied by microincineration and in stained control sections. A marked difference in concentration and distribution of mineral salts was noted within saprozoic and holozoic organisms. The endoplasm in the saprozoic protozoa was free from inorganic residue except for the ‘vegetative’ granules; the protoplasm of the holozoic infusorians consisted of a fine network of mineral salts. Detailed examinations suggested that the qualitative and quantitative differences might be correlated with diffusion of digestible material through the cuticle. The inorganic residue of the walls of vacuoles was relatively rich in iron.
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  • 59
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    Journal of Morphology 54 (1933), S. 451-457 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Recent and fossil fishes may be divided into groups having both pectoral and pelvic fins, pectorals only, pelvics only, or with a second pair of fins located anteriorly and seemingly not homologous with pelvics. In some groups the pelvics are located near the cloaca, with an extensive hiatus between the pectoral and pelvic neuromeres; other groups are of an intermediate character, while in a third group the second pair of fins appears to have no relationship to the pelvics. The character of the innervation indicates that they could hardly have been derived from the latter, and the few nerves, consecutive with the brachial plexus, which supply them suggest origin from the posterior elements of the dermal series, the anterior of which became the pectoral fins. Instances even occur (Polynemus) in which a third pair of appendages has been derived from the original pectoral complex.
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  • 60
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The authors are preparing a table for the normal developments of the guinea-pig. This paper deals with the external form and the development of the external characteristics of guinea-pigs between 21 days and 35 days, copulation age. About one hundred embryos were used from thirty-six litters.Length and weight are good criteria for determining age, although there is some variation. The flexures, the disappearance of the tail, the development of hair follicles at specific locations, the degree of development of the mouth and external ear are better criteria for the determination of age.At 27 days there is a sudden increase in both weight and length. This increase is rather uniform from this period until the end of 35 days. At this time the embryo has the appearance of a newborn guinea-pig.
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  • 61
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Basophiilic granule cells which occur in vast number in the connective tissue throughout all regions of the alimentary canal of sockeye salmon and speckled trout are interpreted as histogenous mast cells. Their occurrence in several other species is noted. None could be found in blood or in any other organs. Their development from mesenchymal cells is described (speckled trout). Their function or possible relationship to functional conditions of the tract could not be determined. Experiments showed the granules to be quickly destroyed by acids and bases but not by water in the fresh condition, but they were extremely stable structures after Helly fixation. In living cells, the granules are probably fluid, and consist of proteins. There was no indication of the granules being composed of mucin, or of the cells being degenerated forms. The granules are basophilic at all times.
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  • 62
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    Journal of Morphology 55 (1933), S. 81-118 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The development of the interatrial septum and the relation of the sinus venosus and sino-atrial valves to the interatrial septum was followed in chick hearts ranging from 50 hours of incubation to the adult. The following singificant facts were established. The interatrial septum first appears at about 50 to 55 hours of incubation. It fuses with the endocardial cushions of the atrio-ventricular canal, typically in the last quarter of the fifth day. Secondary perforations appear in the septum at the time of closure of the interatrial foramen primum. These are retained until hatching, although they may persist in the adult heart. The sinus venosus, a sinus septum, and the sino-atrial valves are retained as definite structures in the adult fowl heart. The pulmonary vein and the left precava as they enter the heart form a prominent addition to the inter-atrial septum proper which I have designated as the pars cavo-pulmonalis. The pulmonary orifice in the left atrium is provided with an extensive flap-like valve. A prominent limbus of Vieussens is present in the right atrium. A well-developed median muscular arch overlies the interatrial septum and a pair of lateral muoscular arches extend over the atria. Their position would seem to be significant in the closing septal perforations during atrial systole.
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  • 63
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The alignment and condition of mitochondria in the epithelial cells indicate that secretion is apparently the chief function of the midgut and the attached caeca. In view of the response of these cells to vital dyes, and to various fixatives, other cell structures-particularly vacuoles-are uncertain evidence of cell activities. Many structures visible by means of vital dyes indicate changes in the permeability of the cell membrane, and subsequently in the cytoplasm. Hence, they are artifacts, just as truly as those found in fixed tissue.
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  • 64
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    Journal of Morphology 55 (1933), S. 137-149 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mid-dorsal protective hair-shafts from forty-five species of Soricidae were studied with the object of investigating the relation between the differences in certain microscopic structural elements and the diameters of the shafts in which they were developed, and the possible occurrence of specific characters in these elements. In comparing like portions of like hair-shafts, it was found that scale- and medulla-forms were related (with slight variations within their form-groups) to the diameters of the hair-shafts in which they were developed. It is possible that further study of these slight variations may show them to be associated with the species bearing the hair.
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  • 65
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    Journal of Morphology 55 (1933) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 66
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    Journal of Morphology 55 (1933), S. 253-263 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A survey of biological literature of the present reveals a tendency to turn to the study of the living cells and tissues. This tendency is indicated by the use of microdissection, ultraviolet microscopes, transparent chambers in rabbits' ears, growing nerve cells and fibers in tailfins of amphibian larvae, and by intravitam technic on insect germ cells. The division stages of the germ cells of Anasa tristis which were carefully studied and drawn thirty-odd years ago are now shown by actual unretouched photomicrographs. These photomicrographs confirm the drawings in many points and show other structures such as mitochondria even more clearly than the drawings do. An account of a peculiarly shaped spermatozoon which has not been described heretofore in the literature is added. The question of the great variations of shapes of spermatozoa is discussed. The advantages of the use of methods for studying living cells, especially of intravitam technic, is emphasized.
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  • 67
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    Journal of Morphology 54 (1933), S. 593-615 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The nuclear changes involved in the two maturation divisions of G. japonicus have been studied in considerable detail. All observations compel a telosynaptic interpretation. The duality, an apparent parasynapsis, as seen beginning from synizesis up to diplotene is a result of a longitudinal splitting of the chromosomes joined end to end. Strepsinema is brought about by breaking up of the diplotene thread into segments, which really are pairs of synaptic mates in end-to-end union; each segment then bends at its middle to form V- or ring-tetrads. There are altogether twenty tetrads. All chromosomes assume a rod shape when in the metaphase plate. A pair of heterochromosomes was observed to be slower than the rest in assuming the rod shape and in getting into the plate. The marching of the synaptic mates toward their respective poles is asynchronous. Second division begins right after the chromosomes have reached the poles. Zwischenkörper observed at the end of the second division are regarded as formed by the granules seen in the polar regions during the first division.
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  • 68
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    Journal of Morphology 55 (1933), S. 15-28 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The first stage in the formation of the liver is two ventrolateral evaginations of the mid-gut at the time of hatching. From the undifferentiated cells branching from the liver duct the pancreas cells arise, but do not assume adult character until the carp is about 41 mm. long.The islet makes its first appearance in the region of the pancreatic duct at the 8-mm. stage and shows no transitional stages. In the mesenchyme itissue dorsal to the intestine the spleen arises, and is finally completely surrounded by the liver-pancreas.
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  • 69
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    Journal of Morphology 55 (1933), S. 185-191 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In this peculiar Orthopteron the chromosomes are unusual in these respects: the number is low for one of the Saltatoria; there is an x-y idiochromosome pair; all the tetrads are individually distinguishable; the chromosomes are small, relatively and actually, in the very large first spermatocyte. The structural peculiarities of the animal are reflected in those of its germ cells, but as yet no correlation has been established.
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  • 70
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    Journal of Morphology 55 (1933), S. 193-205 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Tritrichomonas foetus (Riedmüller) which occurs in the genital tract of domestic cows and which appears to be associated with pathological conditions, including sterility and abortion, has been found in American cows and its morphology studied.The spindle-shaped body is 10 to 25 μ in length and bears three anterior flagella and a posterior flagellum which constitutes the marginal filament of the nearly full-length undulating membrane and continues posteriorly as a trailing flagellum. There is an accessory filament in the undulating membrane. The axostyle is of the thick, hyaline type and contains endoaxostylar granules in the capitulum and bears a chromatic ring at the point of emergence from the body. There is a well-developed costa under the undulating membrane and a simple type of parabasal body.In its morphology this species more nearly resembles such intestinal forms as T. augusta and T. muris than it does Trichomonas vaginalis of man, since the latter has four anterior flagella, a short undulating membrane without an accessory filament, no trailing flagellum, a different type of axostyle, and a parabasal filament along with its larger parabasal body.
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  • 71
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    Journal of Morphology 55 (1933), S. 265-311 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: X-rays produce fragmentations of the chromosome commonly in the region of fiber attachment.Fiberless fragments become attached to other chromosomes or those portions of them that retain fiber attachments. Thus, chromosomes homologous to parts of two other chromosomes are produced and at synapsis multiples are formed. Such multiples are chains or closed-circles depending upon whether a single or a reciprocal translocation respectively has occurred. Sometimes entire chromosomes unite to form a multiple. In general, the multiples divide so that the segregation of homologous elements is complete. However, sometimes the separation of homologous portions is impossible and, then, gametes which contain sectional-duplications, or sectional-deficiencies, or both, are produced. Any two or more chromosomes may be involved in multiple formation although the larger elements are more frequently implicated.Translocations may occur between homologues resulting in an unequal division of chromatin.The locus of fiber attachment (acromite) is an integral part of a chromosome and its loss to one homologue causes non-disjunction or other inequalities in the distribution of the chromatin.Supernumerary chromosomes are frequently present in the spermatocytes.Homologues unaccountably sometimes fail to synapse in the descendants of irradiated cells.There is a striking similarity between natural and induced chromosomal aberrations as well as a correlation between the distribution of radioactive minerals and naturally occurring aberrations.
    Additional Material: 2 Ill.
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  • 72
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: S. scalaris (Orthoptera, Truxalinae) from Scotland and Siberia has a diploid complex of seventeen chromosomes (six V-multiples and eleven rods). Each element possesses a polar or proximal granule recognizable throughout all stages of prophase of the first spermatocyte and in all other stages when concentration is not so great as to mask it. In telophase of the first spermatogonial division the polar granules may fuse into a single body or into several irregular bodies (chromoplasts of Eisen and Janssens). By the end of the diatene stage the chromoplast is completely resolved into its component granules which are clearly recognizable as the proximal parts of the rods (ends) and of the multiples (mid-portions). The accessory chromosome is precocious in its behavior and differential in structure at all stages, but its peculiarities are most marked in metaphase of the first spermatocyte where it becomes a non-chromatic vesicle with peripheral granules and chromatic core. Each multiple arises from the permanent fusion of two rod elements. They differ from those in other members of the same sub-family in diakinesis (eight-strand or octad stage) in that proximal concentration extends almost throughout the multiple.
    Additional Material: 1 Ill.
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  • 73
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Rats in different stages of maturity were castrated in pairs-bilaterally and unilaterally-with respect to the effects upon the epipidymis. The epididymis was also studied during its developmental stages. A special study was made of the mitochondria and Golgi materials; and a comprehensive review of the literature is included.Bilateral castration was followed by a marked regression of functional activity on the part of the epithelial cells of the epididymis. Unilateral castration produced no similar change. The mitochondria-Golgi complex in the epithelial cells of the epididymis was reduced decidedly following bilateral castration; while unilateral castration had no visible effect upon these materials. The mitochondria-Golgi complex increased and decreased in amounts in keeping with the state of secretory activity of the epithelial cells.Golgi nets were found within the lumina of the tubules. Granules within the cells and the tubules were colored with osmic acid, Altmann's anilin acid-fuchsin, iron hematoxylin, or acid fuchsin-orange G. Osmic acid impregnation was removed from granules and nets and Altmann's anilin acid-fuchsin stain put in its place.It is believed that mitochondria and Golgi materials are very similar and furthermore that they are secretory products of the cells. It is also believed that the state of development of the mitochondria-Golgi complex is an indication of the functional state of the epithelial cells of the epididymis.
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  • 74
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    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 53 (1933) 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 75
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    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 52 (1933), S. 241-271 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 76
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    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 52 (1933) 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 77
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 3 Ill.
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  • 78
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    The @Anatomical Record 55 (1933), S. 403-409 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 79
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 3 Ill.
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  • 80
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    The @Anatomical Record 55 (1933), S. 411-419 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 81
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    The @Anatomical Record 55 (1933), S. 377-394 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 82
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 56 (1933) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 83
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    The @Anatomical Record 56 (1933), S. 195-209 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 84
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 85
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 56 (1933) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 86
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 1 Ill.
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  • 87
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    The @Anatomical Record 56 (1933), S. 229-240 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 4 Tab.
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  • 88
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    The @Anatomical Record 56 (1933), S. 255-259 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 89
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    The @Anatomical Record 56 (1933), S. 261-273 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 90
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    The @Anatomical Record 56 (1933), S. 295-305 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 3 Ill.
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  • 91
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    The @Anatomical Record 56 (1933), S. 345-358 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 6 Ill.
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  • 92
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 93
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 94
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 56 (1933), S. 395-408 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 95
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    The @Anatomical Record 57 (1933), S. 7-11 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 96
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    The @Anatomical Record 57 (1933), S. 13-27 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 97
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    The @Anatomical Record 57 (1933), S. 29-39 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 98
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 99
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    The @Anatomical Record 57 (1933), S. 204-204 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 100
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 57 (1933) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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