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  • 2000-2004  (275)
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  • 1
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    On Non-Rank Facets of Stable Set Polytopes of Webs with Clique Number Four (2003)
    Details
    Publication Date: 2014-11-10
    Description: Graphs with circular symmetry, called webs, are relevant w.r.t. describing the stable set polytopes of two larger graph classes, quasi-line graphs and claw-free graphs. Providing a decent linear description of the stable set polytopes of claw-free graphs is a long-standing problem. However, even the problem of finding all facets of stable set polytopes of webs is open. So far, it is only known that stable set polytopes of webs with clique number $\leq 3$ have rank facets only while there are examples with clique number $〉4$ having non-rank facets.
    Keywords: ddc:000
    Language: English
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  • 2
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    Multiscale Analysis for the Bio-Heat Transfer Equation (2003)
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    Publication Date: 2014-02-26
    Description: The bio-heat transfer equation is a macroscopic model for describing the heat transfer in microvascular tissue. In [{\sl Deuflhard, Hochmuth 2002}] the authors applied homogenization techniques to derive the bio-heat transfer equation as asymptotic result of boundary value problems which provide a microscopic description for microvascular tissue. Here those results are generalized to a geometrical setting where the regions of blood are allowed to be connected. Moreover, asymptotic corrector results are derived.
    Keywords: ddc:000
    Language: English
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  • 3
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    Polyhedral Investigations on Stable Multi-Sets (2003)
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    Publication Date: 2014-11-10
    Description: Stable multi-sets are an evident generalization of the well-known stable sets. As integer programs, they constitute a general structure which allows for a wide applicability of the results. Moreover, the study of stable multi-sets provides new insights to well-known properties of stable sets. In this paper, we continue our investigations started in [{\sl Koster and Zymolka 2002}] and present results of three types: on the relation to other combinatorial problems, on the polyhedral structure of the stable multi-set polytope, and on the computational impact of the polyhedral results. First of all, we embed stable multi-sets in a framework of generalized set packing problems and point out several relations. The second part discusses properties of the stable multi-set polytope. We show that the vertices of the linear relaxation are half integer and have a special structure. Moreover, we strengthen the conditions for cycle inequalities to be facet defining, show that the separation problem for these inequalities is polynomial time solvable, and discuss the impact of chords in cycles. The last result allows to interpret cliques as cycles with many chords. The paper is completed with a computational study to the practical importance of the cycle inequalities. The computations show that the performance of state-of-the-art integer programming solvers can be improved significantly by including these inequalities.
    Keywords: ddc:000
    Language: English
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  • 4
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    Formation and structure of quasi-static cloud-layers in brown dwarf atmospheres (2003)
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    Publication Date: 2014-02-26
    Description: In this paper, first solutions of the dust moment equations developed in [{\sl Woitke & Helling 2002}] for the description of dust formation and precipitation in brown dwarf and giant gas planet atmospheres are presented. We consider the special case of a static brown dwarf atmosphere, where dust particles continuously nucleate from the gas phase, grow by the accretion of molecules, settle gravitationally and re-evaporate thermally. Applying a kinetic description of the relevant microphysical and chemical processes for TiO$_2$-grains, the model makes predictions about the large-scale stratification of dust in the atmosphere, the depletion of molecules from the gas phase, the supersaturation of the gas in the atmosphere as well as the mean size and the mass fraction of dust grains as function of depth. Our results suggest that the nucleation occu in the upper atmosphere where the gas is cool, strongly depleted, but nevertheless highly supersaturated ($S\!\gg\!1$). These particles settle gravitationally and populate the warmer layers below, where the in-situ formation (nucleation) is ineffective or even not possible. During their descent, the particles grow up to radii $\approx\!0.3\,\mu{\rm m}\,...\,150\,\mu{\rm m}$, depending gas around the cloud base. The particles finally sink into layers which are sufficiently hot to cause their thermal evaporation. Hence, an effective transport mechanism for condensable elements exi considered solid/liquid material. In the stationary case studied here, this downward directed element transport by precipitating dust grains is balanced by an upward directed flux of condensable elements from the deep interior of the star via convective mixing (no dust without mixing). We find a self-regulation mechanism which leads to an approximate phase equilibrium ($S\!\approx\!1$) around the cloud base. The mass fraction of dust present in the atmosphere results be to approximately given by the mass fraction of condensable elements in the gas being mixed up.
    Keywords: ddc:000
    Language: English
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  • 5
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    Visualization of Time-Dependent Adaptive Mesh Refinement Data (2003)
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    Publication Date: 2020-03-09
    Description: Analysis of phenomena that simultaneously occur on quite different spatial and temporal scales require adaptive, hierarchical schemes to reduce computational and storage demands. For data represented as grid functions, the key are adaptive, hierarchical, time-dependent grids that resolve spatio-temporal details without too much redundancy. Here, so-called AMR grids gain increasing popularity. For visualization and feature identification/tracking, the underlying continuous function has to be faithfully reconstructed by spatial and temporal interpolation. Well designed interpolation methods yield better results and help to reduce the amount of data to be stored. We address the problem of temporal interpolation of AMR grid data, e.g.\ for creation of smooth animations or feature tracking. Intermediate grid hierarchies are generated by merging the cells on all refinement levels that are present in the key frames considered. Utilizing a clustering algorithm a structure of nested grids is induced on the resulting collection of cells. The grid functions are mapped to the intermediate hierarchy, thus allowing application of appropriate interpolation techniques.
    Keywords: ddc:000
    Language: English
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  • 6
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    Tensor Splats (2003)
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    Publication Date: 2020-03-09
    Description: An improved general-purpose technique for the visualization of symmetric positive definite tensor fields of rank two is described. It is based on a splatting technique that is built from tiny transparent glyph primitives which are capable to incorporate the full directional information content of a tensor. The result is an information-rich image that allows to read off the preferred directions in a tensor field at each point of a three-dimensional volume or two-dimensional surface. It is useful for analyzing slices or volumes of a three-dimensional tensor field and can be overlayed with standard volume rendering or color mapping. The application of the rendering technique is demonstrated on general relativistic data and the diffusion tensor field of a human brain.
    Keywords: ddc:000
    Language: English
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  • 7
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    A construction for non-rank facets of stable set polytopes of webs (2003)
    Details
    Publication Date: 2014-11-10
    Description: Graphs with circular symmetry, called webs, are relevant for describing the stable set polytopes of two larger graph classes, quasi-line graphs [{\sl Giles and Trotter 1981, Oriolo 2001}] and claw-free graphs [{\sl Galluccio and Sassano 1997, Giles and Trotter 1981}]. Providing a decent linear description of the stable set polytopes of claw-free graphs is a long-standing problem [{\sl Grötschel, Lov\'asz, and Schrijver 1988}]. However, even the problem of finding all facets of stable set polytopes of webs is open. So far, it is only known that stable set polytopes of webs with clique number $\leq 3$ have rank facets only [{\sl Dahl 1999, Trotter 1975}] while there are examples with clique number $\geq 4$ having non-rank facets [{\sl e.g. Liebling et al. 2003, Oriolo 2001, P\^echer and Wagler 2003}]. In this paper, we provide a construction for non-rank facets of stable set polytopes of webs. We use this construction to prove, for several fixed values of $\omega$ including all odd values at least 5, that there are only finitely many webs with clique number $\omega$ whose stable set polytopes admit rank facets only.
    Keywords: ddc:000
    Language: English
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  • 8
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    Automatic Construction of Boundary Parametrizations for Geometric Multigrid Solvers (2003)
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    Publication Date: 2020-11-13
    Description: We present an algorithm that constructs parametrizations of boundary and interface surfaces automatically. Starting with high-resolution triangulated surfaces describing the computational domains, we iteratively simplify the surfaces yielding a coarse approximation of the boundaries with the same topological type. While simplifying we construct a function that is defined on the coarse surface and whose image is the original surface. This function allows access to the correct shape and surface normals of the original surface as well as to any kind of data defined on it. Such information can be used by geometric multigrid solvers doing adaptive mesh refinement. Our algorithm runs stable on all types of input surfaces, including those that describe domains consisting of several materials. We have used our method with success in different fields and we discuss examples from structural mechanics and biomechanics.
    Keywords: ddc:000
    Language: English
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  • 9
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    Combinatorial Packing Problems (2003)
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    Publication Date: 2020-08-05
    Description: This article investigates a certain class of combinatorial packing problems and some polyhedral relations between such problems and the set packing problem.
    Keywords: ddc:000
    Language: English
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  • 10
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    Small Examples of Non-Constructible Simplicial Balls and Spheres (2003)
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    Publication Date: 2014-02-26
    Description: We construct non-constructible simplicial $d$-spheres with $d+10$ vertices and non-constructible, non-realizable simplicial $d$-balls with $d+9$ vertices for $d\geq 3$.
    Keywords: ddc:000
    Language: English
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  • 11
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    A Lagrangian Approach for Integrated Network Design and Routing in IP Networks (2003)
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    Publication Date: 2014-11-11
    Description: We consider the problem of designing a network that employs a non-bifurcated shortest path routing protocol. The network's nodes and the set of potential links are given together with a set of forecasted end-to-end traffic demands. All relevant hardware components installable at links or nodes are considered. The goal is to simultaneously choose the network's topology, to decide which hardware components to install on which links and nodes, and to find appropriate routing weights such that the overall network cost is minimized. In this paper, we present a mathematical optimization model for this problem and an algorithmic solution approach based on a Lagrangian relaxation. Computational results achieved with this approach for several real-world network planning problems are reported.
    Keywords: ddc:000
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  • 12
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    Comparing Restoration Concepts using Optimal Network Configurations with Integrated Hardware and Routing Decisions (2003)
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    Publication Date: 2014-02-26
    Description: We investigate the impact of link and path restoration on the cost of telecommunication networks. The surprising result is the following: the cost of an optimal network configuration is almost independent of the restoration concept if (i) the installation of network elements (ADMs, DXCs, or routers) and interface cards, (ii) link capacities, and (iii) working and restoration routings are simultaneously optimized. We present a mixed-integer programming model which integrates all these decisions. Using a branch-and-cut algorithm (with column generation to deal with all potential routing paths), we solve structurally different real-world problem instances and show that the cost of optimal solutions is almost independent of the used restoration concept. In addition, we optimize spare capacities for given shortest working paths which are predetermined with respect to different link metrics. In comparison to simultaneous optimization of working and restoration routings, it turns out that this approach does not allow to obtain predictably good results.
    Keywords: ddc:000
    Language: English
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  • 13
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    Average Case Analysis of a Hard Dial-a-Ride Problem (2003)
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    Publication Date: 2020-11-13
    Description: In the dial-a-ride-problem (DARP) objects have to be moved between given sources and destinations in a transportation network by means of a server. The goal is to find a shortest transportation for the server. We study the DARP when the underlying transportation network forms a caterpillar. This special case is strongly NP-hard in the worst case. We prove that in a probabilistic setting there exists a polynomial time algorithm which almost surely finds an optimal solution. Moreover, with high probability the optimality of the solution found can be certified efficiently. We also examine the complexity of the DARP in a semi-random setting and in the unweighted case.
    Keywords: ddc:000
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  • 14
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    Asymptotic Mesh Independence of Newton's Method Revisited (2003)
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    Publication Date: 2019-01-29
    Description: The paper presents a new affine invariant theory on asymptotic mesh independence of Newton's method in nonlinear PDEs. Compared to earlier attempts, the new approach is both much simpler and more natural from the algorithmic point of view. The theory is exemplified at collocation methods for ODE boundary value problems and at finite element methods for elliptic PDE problems.
    Keywords: ddc:000
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  • 15
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    Smoothening Helps: A Probabilistic Analysis of the Multi-Level Feedback Algorithm (2003)
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    Publication Date: 2014-02-26
    Description: In this paper we introduce the notion of smoothed competitive analysis of online algorithms. Smoothed analysis has been proposed by [{\sl Spielman and Teng} STOC 2001] to explain the behaviour of algorithms that work well in practice while performing very poorly from a worst case analysis point of view. We apply this notion to analyze the Multi-Level Feedback (MLF) algorithm to minimize the total flow time on a sequence of jobs released over time when the processing time of a job is only known at time of completion. The initial processing times are integers in the range $[1,2^K]$. We use a partial bit randomization model, where the initial processing times are smoothened by changing the $k$ least significant bits under a quite general class of probability distributions. We show that MLF admits a smoothed competitive ratio of $O(max((2^k/\sigma)^3, (2^k/\sigma)^2 2^K-k))$, where $\sigma$ denotes the standard deviation of the distribution. In particular, we obtain a competitive ratio of $O(2^K-k)$ if $\sigma = \Theta(2^k)$. %The analysis holds for an oblivious as well as for a stronger adaptive %adversary. We also prove an $\Omega(2^{K-k})$ lower bound for any deterministic algorithm that is run on processing times smoothened according to the partial bit randomization model. For various other smoothening models, including the additive symmetric smoothening model used by [{\sl Spielman and Teng}], we give a higher lower bound of $\Omega(2^K)$. A direct consequence of our result is also the first average case analysis of MLF. We show a constant expected ratio of the total flow time of MLF to the optimum under several distributions including the uniform distribution.
    Keywords: ddc:000
    Language: English
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  • 16
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    A sample path relation for the sojourn times in G/G/1-PS systems and its applications (2003)
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    Publication Date: 2014-11-11
    Description: For the general G/G/1 processor sharing (PS) system a sample path result for the sojourn times in a busy period is proved, which yields a relation between the sojourn times under PS and FCFS discipline. In particular, the result provides a formula for the mean sojourn time in G/D/1-PS in terms of the mean sojourn time in the corresponding G/D/1-FCFS, generalizing known results for GI/M/1 and M/GI/1. Extensions of the formula provide the basis for a two-moment approximation of the mean sojourn time in G/GI/1-PS in terms of a related G/D/1-FCFS.
    Keywords: ddc:000
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  • 17
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    Molecular Conformation Dynamics and Computational Drug Design (2003)
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    Publication Date: 2014-02-26
    Description: The paper surveys recent progress in the mathematical modelling and simulation of essential molecular dynamics. Particular emphasis is put on computational drug design wherein time scales of $msec$ up to $min$ play the dominant role. Classical long-term molecular dynamics computations, however, would run into ill-conditioned initial value problems already after time spans of only $psec=10^{-12} sec$. Therefore, in order to obtain results for times of pharmaceutical interest, a combined deterministic-stochastic model is needed. The concept advocated in this paper is the direct identification of metastable conformations together with their life times and their transition patterns. It can be interpreted as a {\em transfer operator} approach corresponding to some underlying hybrid Monte Carlo process, wherein short-term trajectories enter. Once this operator has been discretized, which is a hard problem of its own, a stochastic matrix arises. This matrix is then treated by {\em Perron cluster analysis}, a recently developed cluster analysis method involving the numerical solution of an eigenproblem for a Perron cluster of eigenvalues. In order to avoid the 'curse of dimension', the construction of appropriate boxes for the spatial discretization of the Markov operator requires careful consideration. As a biomolecular example we present a rather recent SARS protease inhibitor.
    Keywords: ddc:000
    Language: English
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  • 18
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    Nonlinear Optimization in Gas Networks (2003)
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    Publication Date: 2021-02-01
    Description: The operative planning problem in natural gas distribution networks is addressed. An optimization model focusing on the governing PDE and other nonlinear aspects is presented together with a suitable discretization for transient optimization in large networks by SQP methods. Computational results for a range of related dynamic test problems demonstrate the viability of the approach.
    Keywords: ddc:000
    Language: English
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  • 19
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    RNA 3D-Modeling (2003)
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    Publication Date: 2014-02-26
    Description: This article presents a new computational approach to the three-dimensional (3D) modeling of ribonucleic acid (RNA) sequences with unknown spatial structure. The main concept is a mapping of the query sequence onto the 3D structures of a suitable template RNA molecule. This technique called \textit{threading} has originally been developed for the modeling of protein 3D structures. The application to RNA systems bridges the information gap between the growing mass of RNA sequence data and the relatively limited number of available 3D structures. The new RNA threading method is demonstrated on a tRNA model system because sufficient representative 3D structures have experimentally been elucidated and deposited in the public databases. Nevertheless, the method is in principle transferable on all other RNA species. Algorithms are developed that decompose these template structures into their secondary structure elements and gather this information in a specific template database. The best template is chosen with public alignment and secondary structure prediction tools which are integrated in the RNA modeling module. The structural information gathered from the template and the best alignment is combined to establish a comprehensive 3D model of the query sequence. A range of complete tRNA structures has successfully been modeled with the RNA threading method. The prototype module visualizes the models and provides convenient access to the proposed 3D structures. Therefore, the method could give new insight into a variety of RNA systems which in the recent years have become increasingly important as potential new pharmaceutical agents.
    Keywords: ddc:000
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  • 20
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    Korean-German Bilateral Symposium on Scientific Computing (2003)
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    Publication Date: 2014-02-26
    Description: Collection of abstracts of the Korean-German Bilateral Symposium on Scientific Computing, Berlin January 15/16, 2004
    Keywords: ddc:000
    Language: English
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  • 21
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    Planung kostenoptimaler Informations- und Kommunikations-Infrastrukturen (2003)
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    Publication Date: 2014-11-11
    Description: Beim Entwurf und Ausbau von Informations- und Kommunikationsnetzwerken m{ü}ssen zahlreiche interdependente Entscheidungen getroffen und gleichzeitig mannigfaltige Bedingungen ber{ü}cksichtigt werden. Die verf{ü}gbaren technischen und organisatorischen Alternativm{ö}glichkeiten sind normalerweise so vielf{ä}ltig und komplex, dass eine manuelle Planung praktisch nicht m{ö}glich ist. In diesem Artikel wird das Potential und die Methodik der mathematischen Optimierung bei der kostenoptimalen Planung von Kommunikationsnetzen vorgestellt. Als Ausgangspunkt wird exemplarisch eine typische praktische Aufgabe, die Struktur- und Konfigurationsplanung mehrstufiger Telekommunikationsnetzwerke, dargestellt. Anschließend werden kurz die wesentlichen Modellierungstechniken und Verfahrensans{ä}tze der mathematischen Optimierung skizziert. Abschließend gehen wir auf die Planung einer ad{ä}quaten Informations- und Kommunikations- Infrastruktur f{ü}r ein dezentrales Energieversorgungsnetz ein.
    Keywords: ddc:000
    Language: German
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  • 22
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    Chromatic Scheduling Polytopes coming from the Bandwidth Allocation Problem in Point-to-Multipoint Radio AccessSystems (2003)
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    Publication Date: 2020-08-05
    Description: Point-to-Multipoint systems are one kind of radio systems supplying wireless access to voice/data communication networks. Such systems have to be run using a certain frequency spectrum, which typically causes capacity problems. Hence it is, on the one hand, necessary to reuse frequencies but, on the other hand, no interference must be caused thereby. This leads to the bandwidth allocation problem, a special case of so-called chromatic scheduling problems. Both problems are NP-hard, and there exist no polynomial time approximation algorithms with a guaranteed quality. One kind of algorithms which turned out to be successful for many other combinatorial optimization problems uses cutting plane methods. In order to apply such methods, knowledge on the associated polytopes is required. The present paper contributes to this issue, exploring basic properties of chromatic scheduling polytopes and several classes of facet-defining inequalities.
    Keywords: ddc:000
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  • 23
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    Optimization Methods for UMTS Radio Network Planning (2003)
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    Publication Date: 2020-02-11
    Description: The UMTS radio network planning problem poses the challenge of designing a cost-effective network that provides users with sufficient coverage and capacity. We describe an optimization model for this problem that is based on comprehensive planning data of the EU project MOMENTUM. We present heuristic mathematical methods for this realistic model, including computational results.
    Keywords: ddc:000
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  • 24
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    Assessing Capacity Improvements by Relaying in Cellular Networks (2003)
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    Publication Date: 2014-02-26
    Description: Relaying -- allowing multiple wireless hops -- is a protocol extension for cellular networks conceived to improve data throughput. Its benefits have only been quantified for small example networks. For assessing its general potential, we define a complex resource allocation\slash{}scheduling problem. Several mathematical models are presented for this problem; while a time-expanded MIP approach turns out intractable, a sophisticated column generation scheme leads to good computational results. We thereby show that for selected cases relaying can increase data throughput by 30\% on the average.
    Keywords: ddc:000
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  • 25
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    Minimum Converter Wavelength Assignment in All-Optical Networks (2003)
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    Publication Date: 2014-02-26
    Description: Finding conflict-free wavelength assignments with a minimum number of required conversions for a routing of the lightpaths is one of the important tasks within the design of all-optical networks. We consider this problem in multi-fiber networks with different types of WDM systems. We give a detailed description of the problem and derive its theoretical complexity. For practical application, we propose several sequential algorithms to compute appropriate wavelength assignments. We also perform computational experiments to evaluate their performance. For the iterative algorithms, we identify characteristic patterns of progression. Two of these algorithms qualify for application in practice.
    Keywords: ddc:000
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  • 26
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    Rigid body docking for Virtual Screening (2003)
    Details
    Publication Date: 2014-09-30
    Description: A recently developed algorithm allows Rigid Body Docking of ligands to proteins, regardless of the accessibility and location of the binding site. The Docking procedure is divided into three subsequent optimization phases, two of which utilize rigid body dynamics. The last one is applied with the ligand already positioned inside the binding pocket and accounts for full flexibility. Initially, a combination of geometrical and force-field based methods is used as a Coarse Docking strategy, considering only Lennard-Jones interactions between the target and pharmaceutically relevant atoms or functional groups. The protein is subjected to a Hot Spot Analysis, which reveals points of high affinity in the protein environment towards these groups. The hot spots are distributed into different subsets according to their group affiliation. The ligand is described as a complementary point set, consisting of the same subsets. Both sets are matched in $\mathrm{I\!R}^{3}$, by superimposing members of the same subsets. In the first instance, steric inhibition is nearly neglected, preventing the system's trajectory from trapping in local minima and thus from finding false positive solutions. Hence the exact location of the binding site can be determined fast and reliably without any additional information. Subsequently, errors resulting from approximations are minimized via finetuning, this time considering both Lennard-Jones and Coulomb forces. Finally, the potential energy of the whole complex is minimized. In a first evaluation, results are rated by a reduced scoring function considering only noncovalent interaction energies. Exemplary Screening results will be given for specific ligands.
    Keywords: ddc:000
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    Integrated Optimization of Hardware Configuration and Capacity. Dimensioning in SDH and opaque WDM networks (2003)
    Details
    Publication Date: 2014-02-26
    Description: We suggest a new model for the design of telecommunication networks which integrates decisions about the topology, configuration of the switching hardware, link dimensioning, and protected routing of communication demands. Applying the branch-and-cut-algorithm implemented in our network planning and optimization tool DISCNET, we demonstrate that real-world based network planning instances of such an enhanced model can be solved.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    Verteilter Dokumenten-Speicher, Erfahrungen mit den Kluwer-Daten des Friedrich-Althoff-Konsortiums (2003)
    Details
    Publication Date: 2020-02-11
    Description: Dieser Bericht beschreibt die Erfahrungen und Schlussfolgerungen,die im Rahmen der VDS-Vorstudie bei der Speicherung der vom Friedrich-Althoff-Konsortium lizenzierten Zeitschriften des Kluwer-Verlages gewonnen wurden.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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    Endnutzerbasierte Online-Fernleihe im KOBV - Kurzbeschreibung (2003)
    Details
    Publication Date: 2020-11-13
    Description: Der KOBV setzt für die endnutzerbasierte Online-Fernleihe den Sisis ZFL-Server (Zentraler Fernleih-Server) ein. Mit dem Einsatz des ZFL-Servers können in den Bibliotheken echte Rationalisierungseffekte erzielt werden: Der Server ist in der Lage, Fernleih-Bestellungen an lokale Systeme zu übergeben, so dass sie im lokalen System automatisch - ohne Eingreifen von Bibliotheksmitarbeitern - weiterverarbeitet werden können. Im KOBV können derzeit Sisis- und Aleph-Lokalsysteme diese Schnittstelle voll bedienen. Andere Bibliothekssysteme im KOBV, die diese Schnittstelle nicht bedienen können, werden mittels eines E-Mail-Verfahrens in die Online-Fernleihe integriert. Die vorliegende Kurzbeschreibung der Online-Fernleihe im KOBV soll - im Gegensatz zur Spezifikation, die möglichst vollständig sein sollte - einen leicht verständlichen Einblick in die Abläufe der Online-Fernleihe vermitteln. Nach einem Überblick über zu erwartende Rationalisierungseffekte ist der Ablauf einer Online-Fernleih-Bestellung - veranschaulicht durch eine Graphik mit dem technischen Aufbau im KOBV - kurz dargestellt. \vspace{6mm} {\it Hinweis:} Die von einer Arbeitsgruppe des KOBV erstellte Spezifikation zur Online-Fernleihe ist als ZIB Report 02-30 auf dem Preprint-Server des ZIB veröffentlicht. Siehe: Monika Kuberek (Red.) {\begin{rawhtml} 〈a href="http://www.zib.de/Publications/Reports/ZR-02-30.pdf"〉 〈i〉 Spezifikation für eine Verbund-Fernleih-Software im KOBV〈/i〉 〈/a〉 \end{rawhtml}}
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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    Improved Perron Cluster Analysis (2003)
    Details
    Publication Date: 2014-02-26
    Description: The problem of clustering data can often be transformed into the problem of finding a hidden block diagonal structure in a stochastic matrix. Deuflhard et al. have proposed an algorithm that state s the number $k$ of clusters and uses the sign structure of $k$ eigenvectors of the stochastic matrix to solve the cluster problem. Recently Weber and Galliat discovered that this system of eigenvectors can easily be transformed into a system of $k$ membership functions or soft characteristic functions describing the clusters. In this article we explain the corresponding cluster algorithm and point out the underlying theory. By means of numerical examples we explain how the grade of membership can be interpreted.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    Zur Zugriffskontrolle im KOBV (2003)
    Details
    Publication Date: 2014-02-26
    Description: Mit der Entwicklung des KOBV-Informationsportals soll den Benutzern in der Region Berlin-Brandenburg ein verbesserter Zugang zu Informationsressourcen geboten werden. Einen wesentlichen Anteil diese Auf der Grundlage der Analyse der Rahmenbedingungen werden Anforderungen an die Zugriffskontrolle im KOBV definiert und Lösungsmöglichkeiten auf der Ebene allgemeiner Modelle diskutiert.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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    Navigation in the KOBV-Informationsportal Conceptual View (2003)
    Details
    Publication Date: 2014-02-26
    Description: The KOBV Informationsportal aims to be a universal gateway to the sources of information hosted by the partner libraries from the Berlin-Brandenburg area. Due to the large number of these sources, an intuitive navigation is an essential component of the portal. The navigation-component should preserve the partner libraries? independence and overcome their administrative and technical differences. This paper proposes a collection-level navigation with four dimensions: the sources? subject areas (e.g. the first two levels of DDC), the sources? type (e.g. e-journals, databases, OPACs, etc.), the sources? location (e.g. Berlin, Brandenburg) / the library that hosts that source and the sources? accessing state (e.g. free, restricted, etc.).
    Keywords: ddc:000
    Language: English
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    Polynomial Inequalities Representing Polyhedra (2003)
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    Publication Date: 2014-02-26
    Description: Our main result is that every n-dimensional polytope can be described by at most (2n-1) polynomial inequalities and, moreover, these polynomials can explicitly be constructed. For an n-dimensional pointed polyhedral cone we prove the bound 2n-2 and for arbitrary polyhedra we get a constructible representation by 2n polynomial inequalities.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    The final NETLIB-LP results (2003)
    Details
    Publication Date: 2020-02-11
    Description: The NETLIB has now served for 18 years as a repository of LP problem instances. From the beginning to the present day there was some uncertainness about the precise values of the optimal solutions. We implemented a program using exact rational arithmetic to compute proofs for the feasibility and optimality of an LP solution. This paper reports the \emph{exact} optimal objective values for all NETLIB problems.
    Keywords: ddc:000
    Language: English
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    Dust formation in brown dwarf atmospheres under conditions of driven turbulence (2003)
    Details
    Publication Date: 2014-02-26
    Description: Based on the knowledge gained from direct numerical simulations which are only possible in the microscale regime, a concept of driven turbulence is presented which allows to enter the mesoscopic scale regime. Here, dust formation under stochastic hydro- and thermodynamic conditions is studied: constructively superimposed stochastic waves initiate dust formation by the creation of singular nucleation events. It, hence, results a varying mean grain size and dust density in space and time. The newly formed dust changes the thermodynamic behavior from almost isotherm to adiabatic and chemically depletes the gas phase.
    Keywords: ddc:000
    Language: English
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    Kosten- und Qualitätsoptimierung in Kommunikationsnetzen (2003)
    Details
    Publication Date: 2014-11-11
    Description: Der scharfe Wettbewerb innerhalb der Telekommunikationsbranche zwingt die Netzbetreiber dazu, ihre Investitionen genau zu planen und immer wieder Einsparungsmanahmen durchzuführen. Gleichzeitig ist es jedoch wichtig, die Qualität der angebotenen Dienste zu verbessern, um neue Kunden zu gewinnen und langfristig an sich zu binden. Die mathematische Optimierung bietet sich für viele solcher Aufgabenstellungen als hervorragend geeignetes Planungswerkzeug an. Ziel dieses Artikels ist es, ihre Methodik und ihre Anwendung speziell zur Kosten- und Qualitätsoptimierung in Kommunikationsnetzen vorzustellen. Anhand von vier konkreten Planungsaufgaben aus dem Bereich der Festnetzplanung wird aufgezeigt, wie sich komplexe Zusammenhänge in flexiblen mathematischen Modellen abbilden lassen und welche Verfahren zur automatisierten Bearbeitung der Probleme eingesetzt werden können. Die hier vorgestellten Methoden zeichnen sich insbesondere dadurch aus, dass sie neben hochwertigen Lösungen auch eine Qualittsgarantie liefern, mit der sich die Lsungen fundiert bewerten lassen. Die dokumentierten Ergebnisse aus verschiedenen Industrieprojekten belegen die Eignung und Güte der mathematischen Optimierung für die Praxis.
    Keywords: ddc:000
    Language: German
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    Dust in Brown Dwarfs IV. Dust formation and driven turbulence on mesoscopic scales (2003)
    Details
    Publication Date: 2014-02-26
    Description: Dust formation {in brown dwarf atmospheres} is studied by utilizing a model for driven turbulence in the mesoscopic scale regime. We apply a pseudo-spectral method where waves are created and superimposed {within} a {limited} wavenumber interval. The turbulent kinetic energy distribution follows the Kolmogoroff spectrum which is assumed to be the most likely value. Such superimposed, stochastic waves may occur in a convectively active environment. They cause nucleation fronts and nucleation events and thereby initiate the dust formation process which { continues until} all condensible material is consumed. Small disturbances {are found to} have a large impact on the dust forming system. An initially dust-hostile region, which may originally be optically thin, becomes optically thick in a patchy way showing considerable variations in the dust properties during the formation process. The dust appears in lanes and curls as a result of the interaction with waves, i.e. turbulence, which form larger and larger structures with time. Aiming on a physical understanding of the variability of brown dwarfs, related to structure formation in substellar atmospheres, we work out first necessary criteria for small-scale closure models to be applied in macroscopic simulations of dust forming astrophysical systems.
    Keywords: ddc:000
    Language: English
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    The multi-scale dust formation in substellar atmospheres (2003)
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    Publication Date: 2014-02-26
    Description: Substellar atmospheres are observed to be irregularly variable for which the formation of dust clouds is the most promising candidate explanation. The atmospheric gas is convectively unstable and, last but not least, colliding convective cells are seen as cause for a turbulent fluid field. Since dust formation depends on the local properties of the fluid, turbulence influences the dust formation process and may even allow the dust formation in an initially dust-hostile gas. A regime-wise investigation of dust forming substellar atmospheric situations reveals that the largest scales are determined by the interplay between gravitational settling and convective replenishment which results in a dust-stratified atmosphere. The regime of small scales is determined by the interaction of turbulent fluctuations. Resulting lane-like and curled dust distributions combine to larger and larger structures. We compile necessary criteria for a subgrid model in the frame of large scale simulations as result of our study on small scale turbulence in dust forming gases.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    HelmPole - A finite element solver for scattering problems on unbounded domains: Implementation based on PML (2003)
    Details
    Publication Date: 2019-01-24
    Description: The solution of scattering problems described by the Helmholtz equation on unbounded domains is of importance for a wide variety of applications, for example in electromagnetics and acoustics. An implementation of a solver for scattering problems based on the programming language Matlab is introduced. The solver relies on the finite-element-method and on the perfectly-matched-layer-method, which allows for the simulation of scattering problems on complex geometries surrounded by inhomogeneous exterior domains. This report gives a number of detailed examples and can be understood as a user manual to the freely accessible code of the solver HelmPole.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    Progressive Retrieval and Hierarchical Visualization of Large Remote Data (2003)
    Details
    Publication Date: 2020-03-09
    Description: \noindent The size of data sets produced on remote supercomputer facilities frequently exceeds the processing capabilities of local visualization workstations. This phenomenon increasingly limits scientists when analyzing results of large-scale scientific simulations. That problem gets even more prominent in scientific collaborations, spanning large virtual organizations, working on common shared sets of data distributed in Grid environments. In the visualization community, this problem is addressed by distributing the visualization pipeline. In particular, early stages of the pipeline are executed on resources closer to the initial (remote) locations of the data sets. \noindent This paper presents an efficient technique for placing the first two stages of the visualization pipeline (data access and data filter) onto remote resources. This is realized by exploiting the ``extended retrieve'' feature of GridFTP for flexible, high performance access to very large HDF5 files. We reduce the number of network transactions for filtering operations by utilizing a server side data processing plugin, and hence reduce latency overhead compared to GridFTP partial file access. The paper further describes the application of hierarchical rendering techniques on remote uniform data sets, which make use of the remote data filtering stage.
    Keywords: ddc:000
    Language: English
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    The Potential of Relaying in Cellular Networks (2003)
    Details
    Publication Date: 2014-02-26
    Description: Relaying is a protocol extension for cellular wireless computer networks; in order to utilize radio resources more efficiently, several hops are allowed within one cell. This paper investigates the principle potential of relaying by casting transmission scheduling as a mathematical optimization problem, namely, a linear program. We analyze the throughput gains showing that, irrespective of the concrete scheduling algorithm, performance gains of up to 30\% on average for concrete example networks are achievable.
    Keywords: ddc:000
    Language: English
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    Critical and Anticritical Edges with respect to Perfectness (2003)
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    Publication Date: 2014-02-26
    Description: We call an edge $e$ of a perfect graph $G$ critical if $G-e$ is imperfect and call $e$ anticritical if $G+e$ is imperfect. The present paper surveys several questions in this context. We ask in which perfect graphs critical and anticritical edges occur and how to detect such edges. The main result by [{\sl Wagler, PhD thesis 2000}] shows that a graph does not admit any critical edge if and only if it is Meyniel. The goal is to order the edges resp.~non-edges of certain perfect graphs s.t. deleting resp.~adding all edges in this order yields a sequence of perfect graphs only. Results of [{\sl Hayward 1985}] and [{\sl Spinrad & Sritharan 1995}] show the existence of such edge orders for weakly triangulated graphs; the line-perfect graphs are precisely these graphs where all edge orders are perfect [{\sl Wagler 2001}]. Such edge orders cannot exist for every subclass of perfect graphs that contains critically resp.~anticritically perfect graphs where deleting resp.~adding an arbitrary edge yields an imperfect graph. We present several examples and properties of such graphs, discuss constructions and characterizations from [{\sl Wagler 1999, Wagler PhD thesis 2000}]. An application of the concept of critically and anticritically perfect graphs is a result due to [{\sl Hougardy & Wagler 2002}] showing that perfectness is an elusive graph property.
    Keywords: ddc:000
    Language: English
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    Accelerating Hasenbusch's Acceleration of Hybrid Monte Carlo (2003)
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    Publication Date: 2014-02-26
    Description: Hasenbusch has proposed splitting the pseudo-fermionic action into two parts, in order to speed-up Hybrid Monte Carlo simulations of QCD. We have tested a different splitting, also using clover-improved Wilson fermions. An additional speed-up between 5 and 20\% over the original proposal was achieved in production runs.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    Safe separators for treewidth (2003)
    Details
    Publication Date: 2014-11-10
    Description: A set of vertices $S\subseteq V$ is called a safe separator for treewidth, if $S$ is a separator of $G$, and the treewidth of $G$ equals the maximum of the treewidth over all connected components $W$ of $G-S$ of the graph, obtained by making $S$ a clique in the subgraph of $G$, induced by $W\cup S$. We show that such safe separators are a very powerful tool for preprocessing graphs when we want to compute their treewidth. We give several sufficient conditions for separators to be safe, allowing such separators, if existing, to be found in polynomial time. In particular, every minimal separator of size one or two is safe, every minimal separator of size three that does not split off a component with only one vertex is safe, and every minimal separator that is an almost clique is safe; an almost clique is a set of vertices $W$ such that there is a $v\in W$ with $W-\{v\}$ a clique. We report on experiments that show significant reductions of instance sizes for graphs from proba! bilistic networks and frequency assignment.
    Keywords: ddc:000
    Language: English
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    Interior Point Methods in Function Space (2003)
    Details
    Publication Date: 2019-01-29
    Description: A primal-dual interior point method for optimal control problems is considered. The algorithm is directly applied to the infinite dimensional problem. Existence and convergence of the central path are analyzed, and linear convergence of a short step pathfollowing method is established.
    Keywords: ddc:000
    Language: English
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    Triangulated Manifolds with Few Vertices: Geometric 3-Manifolds (2003)
    Details
    Publication Date: 2014-02-26
    Description: We explicitly construct small triangulations for a number of well-known $3$-dimensional manifolds and give a brief outline of some aspects of the underlying theory of $3$-manifolds and its historical development.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    Lastbalancierung in Peer-to-Peer Systemen (2003)
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    Publication Date: 2016-06-30
    Description: Peer-to-Peer (P2P) Systeme werden u.a. zur Verwaltung von großen Datenmengen benutzt, die auf verschiedene Rechner verteilt sind. Benutzern soll damit der Zugriff auf Daten innerhalb des Systems leicht ermöglicht werden. Damit in P2P Systemen die Daten effizient verteilt und gesucht werden können, existieren Distributed Hash Tables. Distributed Hash Tables (DHT) sind eine Methode, um globale Informationen persistent speichern zu können. Der Wertebereich der Hashfunktion, welche die zu veröffentlichenden Einträge auf Werte abbildet, wird in Abschnitte aufgeteilt, die einzelnen Knoten zugeteilt werden. Die meisten DHTs haben aber ein Problem bei der Verteilung der Last. Die verschiedenen DHT Systeme beruhen meist auf einem identischen Ansatz der Lastverteilung. Die Last wird nur mit Hilfe einer Hashfunktion verteilt. Es wird davon ausgegangen, dass diese Funktion die Last gleichmäßig verteilt. Im Rahmen dieser Arbeit wurde ein Verfahren zur Last Verteilung entwickelt, simuliert und implementiert. Bei dem Verfahren wird die Last wie bei der Verteilung von Wärme an die Umgebung abgegeben. Es wird mit existierenden Lastbalancierungsalgorithmen verglichen. Mit diesem neuen Verfahren ist es möglich, Last in DHTs besser zu verteilen ohne große Änderungen an den DHTs vorzunehmen. Es wird gezeigt, wie mit dem Verfahren zusätzlich die Fehlertoleranz des P2P Systems erhöht werden kann.
    Description: One of the many uses of Peer-to-Peer (P2P) systems is the administration of large data sets that are distributed across different computers, with the goal of facilitating user access to files within the system. Distributed Hash Tables (DHT) are designed to enable the efficient distribution and search of files, by allowing global information to be persistently stored. The range of values of the hash function (the possible entries in the published hash table) are assigned to individual nodes. Most DHTs, however, have a problem with load distribution. The various DHT systems usually operate by distributing load equally among nodes. Thus the load is distributed using the help of the hash function. One assumes this function distributes the load evenly. In the context of this work a method of distributing load has been developed, simulated and implemented. With this method load is transferred in a fashion analogous to the dissipation of heat into the environment. Comparisons with existing algorithms for load balancing are drawn. With the new procedure it is possible to better distribute load in DHTs without requiring major changes to the DHTs themselves. It is shown that with the procedure the fault tolerance of P2P systems may also be increased.
    Keywords: ddc:000
    Language: German
    Type: masterthesis , doc-type:masterThesis
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    Robust Perron Cluster Analysis in Conformation Dynamics (2003)
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    Publication Date: 2014-02-26
    Description: The key to molecular conformation dynamics is the direct identification of metastable conformations, which are almost invariant sets of molecular dynamical systems. Once some reversible Markov operator has been discretized, a generalized symmetric stochastic matrix arises. This matrix can be treated by Perron cluster analysis, a rather recent method involving a Perron cluster eigenproblem. The paper presents an improved Perron cluster analysis algorithm, which is more robust than earlier suggestions. Numerical examples are included.
    Keywords: ddc:000
    Language: English
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    Demand-wise Shared Protection for Meshed Optical Networks (2003)
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    Publication Date: 2014-11-11
    Description: In this paper, a new shared protection mechanism for meshed optical networks is presented. Significant network design cost reductions can be achieved in comparison to the well-known 1+1 protection scheme. Demand-wise Shared Protection (DSP) bases on the diversification of demand routings and exploits the network connectivity to restrict the number of backup lightpaths needed to provide the desired level of prorection. Computational experiments approve the benefits of the concept DSP for cost efficient optical network designs.
    Keywords: ddc:000
    Language: English
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    Simulation of the Human Mandible: Comparison of Bone Mineral Density and Stress/Strain Profiles due to Masticatory Muscles' Traction (2003)
    Details
    Publication Date: 2019-05-10
    Description: The correlation of the inner architecture of bone and its functional loading was already stated by Wolff in 1892. Our objective is to demonstrate this interdependence in the case of the human mandible. For this purpose, stress/strain profiles occuring at a human lateral bite were simulated. Additionally, by a combination of computer graphics modules, a three--dimensional volumetric visualization of bone mineral density could be given. Qualitative correspondences between the density profile of the jaw and the simulated stress/strain profiles could be pointed out. In the long run, this might enable the use of the simulation for diagnosis and prognosis. The solution of the underlying partial differential equations describing linear elastic material behaviour was provided by an adaptive finite element method. Estimates of the discretization errors, local grid refinement, and multilevel techniques guaranteed the reliability and efficiency of the method.
    Keywords: ddc:000
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    MoDySim - A parallel dynamical UMTS simulator (2003)
    Details
    Publication Date: 2014-02-26
    Description: UMTS is a 3rd generation mobile telecommunication system which enables multi-service and multi-bit rate communication going beyond the possibilities of previous systems. The simulator MoDySim models UMTS in great detail. Characteristics of UMTS such as soft hand-over and the interdependency of load and capacity among neighbouring cells are challenges for the parallelisation of such a system. In this paper we explain how the software was parallelised and present performance results of a UMTS simulation for the city of Berlin.
    Keywords: ddc:000
    Language: English
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    A numerical reinvestigation of the Aoki phase with $N_f=2$ Wilson fermions at zero temperature (2003)
    Details
    Publication Date: 2014-02-26
    Description: We report on a numerical reinvestigation of the Aoki phase in lattice QCD with two flavors of Wilson fermions where the parity-flavor symmetry is spontaneously broken. For this purpose the Hybrid Monte Carlo algorithm was used and an explicit symmetry-breaking source term $h\bar{\psi} i \gamma_{5} \tau^{3}\psi$ was added to the Wilson fermion action. The order parameter $\langle\bar{\psi}i\gamma_{5}\tau^{3}\psi\rangle$ was studied at several values of $(\beta,\kappa,h)$ on lattices of sizes $4^4$ to $12^4$. Our largest lattices can be considered as infintely large allowing to extrapolate to $h=0$. The existence of a parity-flavor-breaking phase can be confirmed at $\beta=4.0$ and $\beta=4.3$ while we find no sign of parity-flavor-breaking at $\beta=4.6$ and $\beta=5.0$.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    Clustering by using a simplex structure (2003)
    Details
    Publication Date: 2014-02-26
    Description: In this paper we interpret clustering as a mapping of data into a simplex. If the data itself has simplicial struture this mapping becomes linear. Spectral analysis is an often used tool for clustering data. We will show that corresponding singular vectors or eigenvectors comprise simplicial structure. Therefore they lead to a cluster algorithm, which consists of a simple linear mapping. An example for this kind of algorithms is the Perron cluster analysis (PCCA). We have applied it in practice to identify metastable sets of molecular dynamical systems. In contrast to other algorithms, this kind of approach provides an a priori criterion to determine the number of clusters. In this paper we extend the ideas to more general problems like clustering of bipartite graphs.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    Ein neues Verfahren zur Lösung des Streuproblems der Maxwell-Gleichungen (2003)
    Details
    Publication Date: 2016-06-09
    Keywords: ddc:000
    Language: German
    Type: masterthesis , doc-type:masterThesis
    Format: application/pdf
    Format: application/postscript
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    Jahresbericht 2002 (2003)
    Details
    Publication Date: 2019-10-24
    Keywords: ddc:000
    Language: German
    Type: annualzib , doc-type:report
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  • 56
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    Semantic Annotation in Mathematics and Math-Net (2003)
    Details
    Publication Date: 2022-04-11
    Description: The Web of the future will provide a huge amount of information. We need better ways for dealing with and managing the information. A qualified semantic annotation of the information plays a key role for the Web of the future. This article gives an overview about the efforts of the mathematical community to build up a distributed and open information and communication system for mathematics: the Math-Net. The Math-Net Initiative has developed metadata schemas for some classes of Web resources which are relevant in mathematics. Math-Net Services process this information and enable the user to efficiently search and access the information.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 57
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    A new Finite Element realization of the Perfectly Matched Layer Method for Helmholtz scattering problems on polygonal domains in 2D (2003)
    Details
    Publication Date: 2022-07-07
    Description: In this paper we propose a new finite element realization of the Perfectly Matched Layer method (PML-method). Our approach allows to deal with arbitrary shaped polygonal domains and with certain types of inhomogeneous exterior domains. Among the covered inhomogeneities are open waveguide structures playing an essential role in integrated optics. We give a detailed insight to implementation aspects. Numerical examples show exponential convergence behavior to the exact solution with the thickness of the PML sponge layer.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 58
    Electronic Resource
    Electronic Resource
    Analysis of the Anatomic Changes in the Thoracic Cage After a Lung Resection Using Magnetic Resonance Imaging (2000)
    Springer
    Surgery today 30 (2000), S. 879-885 
    Details
    ISSN: 1436-2813
    Keywords: Key words Lung lobectomy ; Magnetic resonance imaging ; Left ventricular geometry ; Mediastinum ; Diaphragm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The thoracic cage after a lung resection is filled by the remaining lobes, the elevated diaphragm, the diminished thoracic cage, and by mediastinal shifting. The changes in the thorax after a lung resection were quantified using magnetic resonance imaging. The study group consisted of 39 patients who had undergone a lobectomy, four who had undergone a pneumonectomy, and 14 controls. The left ventricular angle, ascending aortic angle, mediastinal shift, longitudinal length of the thoracic cage, the distance between the thoracic apex and the level of the aortic valve, and diaphragmatic elevation were all measured. After a right lower lobectomy, the mediastinum shifted more rightward than after a right upper lobectomy. The diaphragm became more greatly elevated after a right upper lobectomy than after a right lower lobectomy. When a chest wall resection was added to a right upper lobectomy, the mediastinal anatomical changes decreased. After a left upper lobectomy, the degree of mediastinal shifting was greater than after a left lower lobectomy. A left upper lobectomy shifted the mediastinum at the level of the right atrium. This method is easily reproducible and was found to be effective for quantifying the changes in the thorax after a lung resection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005950070038
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  • 59
    Electronic Resource
    Electronic Resource
    Röntgendiagnostik in der Mund-, Kiefer-, Gesichtschirurgie (2000)
    Springer
    Mund-, Kiefer- und Gesichtschirurgie 4 (2000), S. S270 
    Details
    ISSN: 1434-3940
    Keywords: Schlüsselwörter ; Röntgendiagnostik ; Panoramaschichtaufnahme ; Strahlenexposition ; Computertomographie ; Kernspintomographie ; Key words ; X-ray diagnostics ; Panoramic X-ray ; Radiation exposure ; Computed tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary A vital X-ray imaging technique in oral and craniomaxillofacial surgery is the panoramic X-ray. Due to its variety of special projections, including imaging of the transversal level and low exposure to radiation, it is suitable for answering many clinical questions and for diagnostics of various findings. It has become possible to minimize the necessary doses by further development of technology and devices, as well as of X-ray films and by new detection systems, such as sensors or screens. In some clinical cases, the diagnostic deficiencies of conventional imaging techniques make computed tomography (CT) and magnetic resonance (MR) imaging indispensable. Although MR is particularly suitable for soft tissue imaging, it has also become helpful in finding cortical changes by shorter measuring times. In certain cases, e. g., changes to bone metabolism, differentiated methods of nuclear medicine make image-aided analysis of function possible.
    Notes: Zusammenfassung Zentrale Aufnahmeart in der Röntgendiagnostik der Mund-, Kiefer- und Gesichtschirurgie ist die Panoramaschichtaufnahme. Mit ihren zahlreichen Spezialprojektionen einschließlich der Abbildung der Transversalebene ist sie für die Abklärung zahlreicher Fragestellungen mit geringer Strahlenexposition geeignet. Die Verringerung des Dosisbedarfs ist weiterhin durch Fortentwicklungen der Gerätetechnik, der Röntgenfilme und durch neue Detektionssysteme wie z. B. Sensoren oder Speicherfolien möglich geworden. Diagnostische Unzulänglichkeiten der konventionellen Aufnahmearten machen bei zahlreichen klinischen Fragestellungen der Mund-, Kiefer- und Gesichtschirurgie eine Bildgebung mittels Computertomographie und Kernspintomographie unumgänglich. Obgleich die Kernspintomographie v. a. für die Weichteildiagnostik vorrangig geeignet ist, erlaubt sie mittlerweile, aufgrund der Verkürzung der Messzeiten, auch Veränderungen der Kortikalis abzubilden. Bei bestimmten Fragestellungen, wie z. B. Veränderungen des Knochenmetabolismus, ermöglichen differenzierte nuklearmedizinische Verfahren eine abbildungsunterstützte Funktionsanalyse.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00014549
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  • 60
    Electronic Resource
    Electronic Resource
    Radiologic anatomy of the spinal dorsal horn at the cervical level (anatomic-MRI correlations) (2000)
    Springer
    Surgical and radiologic anatomy 22 (2000), S. 81-88 
    Details
    ISSN: 1279-8517
    Keywords: Spinal cord ; Dorsal horn ; Magnetic resonance imaging ; Radiologic anatomy ; Dorsal root entry zone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The spinal dorsal horn is known for its important functional role in the field of transmission and modulation of sensory afferents. Because of this, the dorsal horn represents a target for numerous analgesic and antispastic procedures. Thus, it would be interesting to develop imaging dedicated to this spinal structure. The purpose of this study was to investigate the radiologic anatomy of the cervical dorsal horn by magnetic resonance imaging (MRI) (1.5T). The first step consisted in the validation of the anatomic information provided by MRI on 5 human cadavers. A spin-echo sequence (T2, 2000/45) enabled the demonstration of good correlations between histologic sections and axial MRI slices performed at the corresponding cervical levels. The second step was the 〈〈in vivo〈〈 exploration of 20 subjects, aiming at the development of a gradient echo sequence (T2*) with a conventional MRI unit, compatible with a routine clinical examination. The dorsal horn was clearly identified in 77% of the axial slices performed (n = 300). The angle between the dorsal horn axis and the sagittal plane was measured as from 25.5˚ at C2 to 40˚ at C8 segments. The results of this anatomico-radiologic study of the cervical dorsal horn suggest that preoperative MRI could be useful to design the surgical approach to this structure, as performed during cervical microsurgical drezotomy (DREZ = dorsal root entry zone) for the treatment of selected cases of chronic pain or disabling spasticity in the upper limbs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00276-000-0081-8
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  • 61
    Electronic Resource
    Electronic Resource
    Pneumocolography and virtual colonoscopy: its clinical place and development (2000)
    Springer
    Techniques in coloproctology 4 (2000), S. 129-131 
    Details
    ISSN: 1128-045X
    Keywords: Key words Colonscopy ; CT scanning ; Magnetic resonance imaging ; Virtual colonoscopy ; Pneumocolography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Colonoscopy is an invasive technique, frequently incomplete and often poorly tolerated in elderly patients. New, less invasive modalities are being developed to diagnose moderate-sized adenomatous polyps and colorectal caners which involve pneumo- or hydrocolography with high-resolution surface imaging, either by CT or MR scanning. This approach has recently been supplemented by complex image post-processing to provide a form of virtual colonoscopy which takes account of projected colonic direction and which can map for mucosal anomalies. It remains to be seen how sensitive these newer techniques are and whether defined algorithms for colonic representation can be agreed upon which will prove both accurate and cost-effective both in symptomatic and screening populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s101510070002
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  • 62
    Electronic Resource
    Electronic Resource
    Is there a brainstem generator of chronic daily headache? (2000)
    Springer
    The journal of headache and pain 1 (2000), S. 67-71 
    Details
    ISSN: 1129-2377
    Keywords: Key words Chronic daily headache ; Migraine ; Magnetic resonance imaging ; Red nucleus ; Substantia nigra ; Image processing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Using BOLD-fMRI we have previously documented activation of the red nucleus (RN) and substantia nigra (SN) during spontaneously and visually activated migraine headache. These observations prompted us to study brainstem function in chronic daily headache patients using high-resolution magnetic resonance imaging (MRI) techniques. Seventeen chronic daily headache (CDH) patients, ten episodic migraine (EM) patients and fifteen controls (N) were imaged with a 3 tesla MRI system. For each subject, the relaxation rates R2, R2* and R2' were obtained for RN and SN. There was a significant decrease in R2' and R2* values for RN and SN in CDH compared to N and EM groups (p 〈 0.05), but no significant difference between the N and EM groups. A decrease in R2' and R2* indicates reduced deoxyhemoglobin and hence persistent activation of the RN and SN in CDH patients most likely secondary to ongoing headache at the time of study. The imaging data provide objective evidence of disturbed central nervous system function in CDH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s101940070045
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  • 63
    Electronic Resource
    Electronic Resource
    Subependymoma of the lateral ventricles (2000)
    Springer
    Neurosurgical review 23 (2000), S. 98-103 
    Details
    ISSN: 1437-2320
    Keywords: Key words Computed tomography ; Magnetic resonance imaging ; Lateral ventricle ; Subependymoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Four subependymomas of the lateral ventricle were reviewed with regard to clinical presentation, neuroimaging features, treatment, histopathological features, and long-term follow-up. There were two male and two female patients ranging in age from 27 to 60 years (mean 48.3 years). While two patients presented with symptoms and signs of raised intracranial pressure, two others were found incidentally during neuroimaging investigations to have intraventricular tumors. Neuroimaging characteristics of these tumors included no paraventricular extension, iso- or hypodensity with minimal enhancement on computerized tomography (CT), or iso- or hypointensity on T1-weighted and hyperintensity on T2-weighted magnetic resonance images (MRI). The usual finding on MRI was of no or scarce contrast enhancement, but one case showed heterogeneous enhancement. Three patients underwent total resection of the tumor and one underwent partial resection. No patients received postoperative radiation therapy. All patients have been doing well 4.8 to 15.4 years (mean 8.8 years), after surgery. Although there are no absolutely specific features to distinguish these tumors from other intraventricular tumors preoperatively, subependymoma should be kept in mind for differential diagnosis, as this tumor may safely be removed without sacrificing contiguous normal tissue and with good long-term results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s101430050008
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  • 64
    Electronic Resource
    Electronic Resource
    Preoperative staging of rectal cancer (2000)
    Springer
    International journal of colorectal disease 15 (2000), S. 9-20 
    Details
    ISSN: 1432-1262
    Keywords: Keywords Rectal cancer staging ; Computed tomography ; Endorectal sonography ; Magnetic resonance imaging ; Systematic review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  With the widespread introduction of preoperative radiotherapy for rectal cancer and the development of transanal endoscopic microsurgery for selected early lesions, preoperative radiological staging of these tumours has taken on increasing importance. This study is a systematic review to evaluate computed tomography (CT), endorectal sonography (ES) and magnetic resonance imaging (MRI) as preoperative staging modalities in rectal cancer. A Medline-based search identifying studies using CT, ES, or MRI in preoperative staging of rectal cancer between 1980 and 1998 was undertaken. The list of papers was supplemented by extensive cross-checking of citation lists. Studies were included if they met predetermined criteria. Data from the accepted studies were entered into pooled tables comparing radiological and pathological staging results for each modality both in determining bowel wall penetration and involvement of lymph nodes. Accuracy, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio and negative likelihood ratio were determined for the pooled results. Eighty-three studies from 78 papers including 4897 patients met the inclusion criteria. In determining the wall penetration of the tumour the values for sensitivity for CT, ES, MRI and MRI with endorectal coil were 78%, 93%, 86% and 89%; for specificity 63%, 78%, 77% and 79%; and for accuracy 73%, 87%, 82% and 84%, respectively. In determining the nodal involvement by tumour the sensitivity values for CT, ES, MRI and MRI with endorectal coil 52%, 71%, 65% and 82%; for specificity 78%, 76%, 80% and 83%; and for accuracy 66%, 74%, 74% and 82%, respectively. MRI with an endorectal coil is the single investigation that most accurately predicts pathological stage in rectal cancer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003840050002
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  • 65
    Electronic Resource
    Electronic Resource
    Macrodystrophia lipomatosa with associated fibrolipomatous hamartoma of the median nerve (2000)
    Springer
    Pediatric surgery international 16 (2000), S. 216-218 
    Details
    ISSN: 1437-9813
    Keywords: Key words Macrodystrophia lipomatosa ; Fibrolipomatous hamartoma ; Magnetic resonance imaging ; Median nerve
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Macrodystrophia lipomatosa (MDL) is a rare disease typically causing localized gigantism and is often associated with a fibrolipomatous hamartoma (FH) of the median or plantar nerve. A previously unreported case of MDL with associated FH of the median nerve is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003830050728
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  • 66
    Electronic Resource
    Electronic Resource
    Imaging of plant-thorn synovitis (2000)
    Springer
    Skeletal radiology 29 (2000), S. 605-608 
    Details
    ISSN: 1432-2161
    Keywords: Keywords Plant-thorn synovitis ; Monoarticular arthritis ; Elbow ; Magnetic resonance imaging ; Ultrasound ; Power Doppler
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We describe a case of plant-thorn synovitis of the elbow resulting from a thorn injury. This caused recurrent pain and swelling of the elbow over a 3-month period. A magnetic resonance imaging examination was initially requested to exclude septic arthritis, and demonstrated a joint effusion, synovitis, and a 2-cm linear opacity embedded in the synovium. Ultrasound was performed prior to surgery to confirm these findings and provide accurate localization of the thorn fragment, later removed at surgery. To our knowledge this is the first example of this condition that has been confirmed by radiological imaging prior to surgery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560000244
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  • 67
    Electronic Resource
    Electronic Resource
    Effect of low back posture on the morphology of the spinal canal (2000)
    Springer
    Skeletal radiology 29 (2000), S. 217-223 
    Details
    ISSN: 1432-2161
    Keywords: Key words Spinal canal ; Low back posture ; Morphologic change ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. To define the possible mechanism of posture-dependent symptoms of spinal stenosis by measuring the effect of low back posture on morphologic changes of the intervertebral discs and spinal canal in healthy young people. Design.Twenty healthy young volunteers underwent magnetic resonance imaging while supine with their spine in neutral, flexed, extended, and right and left rotational positions. The axial MR images at the middle of the intervertebral discs of L3–4 and L4–5 were analyzed to measure the difference in the size and shape of the intervertebral discs and spinal canal in each posture. Results.  Extension or rotation decreased the sagittal diameters and cross-sectional areas of the dural sac and spinal canal and increased the thickness of the ligamentum flavum, whereas flexion had the opposite effects. The gap between the convex posterior disc margin and the anterior margin of the facet joint on each side, represented as the subarticular sagittal diameter, increased with flexion and decreased with extension or rotation. The direction of rotation did not result in asymmetry of the subarticular sagittal diameter, but right rotation caused thickening of the right ligamentum flavum, and vice versa. The shape and dimensions of the disc did not change significantly according to the positions of the low back. Conclusions.With extension or rotation, the thickness of the ligamentum flavum increased and the posterior margin of the intervertebral disc was approximated to the facet joint without any change in shape and size of the disc. These phenomena result in a decrease in the size of the spinal canal and dural sac in extension or rotation postures in young healthy people without disc degeneration, and may explain the posture-dependent symptom of spinal stenosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560050596
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  • 68
    Electronic Resource
    Electronic Resource
    Complete rupture of the distal semimembranosus tendon with secondary hamstring muscles atrophy: MR findings in two cases (2000)
    Springer
    Skeletal radiology 29 (2000), S. 362-364 
    Details
    ISSN: 1432-2161
    Keywords: Key words Hamstring muscles ; Semimenbranosus ; Tear ; mass ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Complete rupture of the hamstring muscles is a rare injury. The proximal musculo-tendinous junction is the most frequent site of rupture. We present two cases of complete rupture of the distal semimenbranosus tendon, which clinically presented as soft-tissue masses. MR imaging permitted the correct diagnosis. There has been only one other such case reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560000216
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  • 69
    Electronic Resource
    Electronic Resource
    Solid aneurysmal bone cyst in the humerus (2000)
    Springer
    Skeletal radiology 29 (2000), S. 470-473 
    Details
    ISSN: 1432-2161
    Keywords: Key words Aneurysmal bone cyst ; Humerus ; Giant cell reparative granuloma ; Pathological fracture ; Radiography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We report on a 69-year-old woman with a solid variant of aneurysmal bone cyst (solid ABC) in the left humerus with a pathological fracture. Radiographically, the lesion exhibited a relatively well-defined osteolytic lesion in the diaphysis of the left humerus. On magnetic resonance (MR) imaging, the medullary lesion exhibited a homogeneous signal intensity isointense with surrounding normal muscles on the T1-weighted images and a mixture of low and high signal intensity on the T2-weighted images. Contrast-enhanced T1-weighted images revealed diffuse enhancement of the entire lesion. The pathological study showed a proliferation of fibroblasts, histiocytes, chronic inflammatory cells and numerous multinucleated giant cells in a collagenous matrix. Abundant osteoid formation in the matrix was observed, but the cells were devoid of nuclear atypia. Aneurysmal cystic cavities were absent. A review of the English literature found 22 cases of solid ABC of the long bones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560000236
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  • 70
    Electronic Resource
    Electronic Resource
    Juxta-articular hemangioma of long bone (2000)
    Springer
    Skeletal radiology 29 (2000), S. 535-537 
    Details
    ISSN: 1432-2161
    Keywords: Key words Computed tomography ; Intraosseous hemangioma ; Magnetic resonance imaging ; Epiphysis equivalent ; Tibia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We report on a rare case of an intraosseous hemangioma involving the proximal tibia in a 70-year-old man. Radiographically, the lesion was a well-defined osteolytic lesion with marginal sclerosis. The CT images demonstrated a well-defined osteolytic lesion with partial cortical breakthrough. T1-weighted MR images showed a hypointense lesion, while T2-weighted images revealed hyperintense areas, with internal, hypointense septa. Gadolinium-enhanced T1-weighted images showed lattice-like enhancement of the lesion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560000256
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  • 71
    Electronic Resource
    Electronic Resource
    Subcutaneous and musculoskeletal sparganosis: imaging characteristics and pathologic correlation (2000)
    Springer
    Skeletal radiology 29 (2000), S. 402-408 
    Details
    ISSN: 1432-2161
    Keywords: Key words Soft tissue ; Magnetic resonance imaging ; Sparganosis ; Sparganosis ; magnetic resonance imaging ; Sparganosis ; ultrasonography ; Parasitic infection ; Sparganum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. To document the imaging characteristics of subcutaneous and musculoskeletal sparganosis. Design and patients. Ten patients with musculoskeletal sparganosis were examined, with a variety of imaging modalities including MRI (n=6), ultrasonography (n=8), plain radiography (n=7) and CT (n=1). Pathologic correlation was carried out in all cases. Results. Nine lesions involved soft tissues, of which seven were in the thigh, two in the trunk and one involved a vertebral body. The majority of the lesions in soft tissue were confined to the subcutaneous layer but two extended deep into underlying muscles. Sonography revealed low-echoic serpiginous tubular tracts (8/8), and an intraluminal echogenic structure (4/8). MRI revealed multiple serpiginous tubular tracts and peripheral rim enhancement. Two patients showed perilesional soft tissue edema. Pathologically, the lesion consisted of a larva surrounded by three layers of inflammation: an inner epithelioid granulomatous cell layer, middle chronic inflammatory cell layers, and an outer fibrous layer. Conclusion. The study suggests that if serpiginous tubular tracts are seen at imaging studies, musculoskeletal sparganosis should be included in the differential diagnosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560000206
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  • 72
    Electronic Resource
    Electronic Resource
    Pectoralis major muscle and tendon tears: diagnosis and grading using magnetic resonance imaging (2000)
    Springer
    Skeletal radiology 29 (2000), S. 305-313 
    Details
    ISSN: 1432-2161
    Keywords: Key words Pectoralis major muscle ; Magnetic resonance imaging ; Tendons ; injuries ; Tendons ; magnetic resonance imaging ; Muscles ; injuries ; Muscles ; magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. To assess the accuracy and utility of magnetic resonance (MR) imaging in the detection and grading of pectoralis major muscle and tendon tears. Design and patients. A retrospective review was carried out of 10 patients referred for MR imaging for suspected pectoralis muscle injury and possible operative therapy. The pectoralis muscle and tendon were imaged using thin (3–4 mm) axial sections with a variety of sequences combined for anatomical delineation (T1-weighted SE or PD SE) and fluid detection (T2-weighted SE, T2-weighted FSE with fat suppression, or STIR). Surgical correlation was available in six patients. Clinical follow-up was available in four patients treated by nonoperative therapy. Results. MR imaging identified five complete tears, four partial tears and one normal tendon. One complete and one partial tear were at the myotendinous junction. The remaining seven injuries were at the enthesis. Surgical correlation consisted of five complete tears and one partial tear. One complete and one partial tear were at the myotendinous junction with the remaining four complete tears at the enthesis. The MR interpretation and surgical findings were in agreement in all six cases. All four patients treated with nonoperative therapy demonstrated improvement at a clinical follow-up examination, with restoration of function and strength consistent with a healed prior partial injury. Conclusion. MR imaging is accurate and useful in detecting and grading tears involving the pectoralis major muscle and tendon, facilitating the identification of patients with complete tears who are candidates for operative therapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560000199
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  • 73
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    Imaging in isolated sacral tuberculosis: a review of 15 cases (2000)
    Springer
    Skeletal radiology 29 (2000), S. 392-396 
    Details
    ISSN: 1432-2161
    Keywords: Key words Sacral ; Tuberculosis ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. To review imaging studies of isolated involvement of the sacrum due to tuberculosis and determine the role of imaging in the diagnosis and management of these patients. Design and patients. A retrospective analysis of 15 cases of isolated sacral tuberculosis imaged with MR imaging was performed. The CT images were also reviewed where available, and the various lesion characteristics were identified. We also reviewed the medical records in an attempt to determine the impact of the imaging studies on the management of these patients. Results. Fifteen patients (5 male, 10 female) presented with symptoms of 3–15 months’ duration. Chronic localized backache with muscle spasm was the commonest presenting symptom; discharging sinuses with abscess formation was found in six patients, five of whom were children. MR imaging of the sacrum revealed a hypointense marrow signal on T1-weighted images and hyperintense signal on T2-weighted images in 14 of 15 patients, the S2 vertebra being always involved. CT revealed osteolytic changes in the sacrum in all the five patients in whom CT was performed. All patients showed marked clinical improvement within 1 year of anti-tuberculous chemotherapy. Conclusion. Isolated tuberculosis of the sacrum is uncommon but should be suspected in patients presenting with chronic low backache or children with discharging sinuses/abscesses and showing sacral destruction on CT or MR imaging. MR imaging can identify cases and enables early institution of anti- tuberculous chemotherapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560000229
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  • 74
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    Electronic Resource
    Juxtacortical chondromyxoid fibroma arising in an apophysis (2000)
    Springer
    Skeletal radiology 29 (2000), S. 466-469 
    Details
    ISSN: 1432-2161
    Keywords: Key words Bone neoplasm ; Chondromyxoid fibroma ; Femur ; Apophysis ; Radiography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We present a rare case of juxtacortical chondromyxoid fibroma arising in the lesser trochanter of the right femur which corresponds to an apophysis. Radiography showed a well-defined expansive lesion with a sclerotic margin measuring 5×3.5 cm in diameter in the lesser trochanter. On spin echo T1-weighted images, the lesion revealed low signal intensity similar to muscle. On spin echo T2-weighted images, the lesion revealed high heterogeneous signal intensity, which after gadolinium injection showed heterogeneous enhancement. The inner margin of the cortex was intact and adjacent bone marrow was of normal signal intensity. The outer margin of the lesion was also clearly defined and extension into adjacent soft tissue beyond the exophytic cortical outgrowth was not evident.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560000245
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  • 75
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    Electronic Resource
    Familial occurrence of glenoid dysplasia: report of two cases in two consecutive generations (2000)
    Springer
    Archives of orthopaedic and trauma surgery 120 (2000), S. 349-351 
    Details
    ISSN: 1434-3916
    Keywords: Key words Glenoid dysplasia ; Magnetic resonance imaging ; Multidirectional shoulder dislocation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Glenoid dysplasia is a rare abnormality of the shoulder. We report glenoid dysplasia in two consecutive generations: a boy and his father. Both suffered recurrent shoulder dislocations, and radiological examination revealed bilateral glenoid dysplasia. Our cases confirm dominant inheritance of this osseous malformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004020050481
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  • 76
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    Diagnostic and therapeutic management of lumbar and thoracic spondylodiscitis – an evaluation of 59 cases (2000)
    Springer
    Archives of orthopaedic and trauma surgery 120 (2000), S. 245-251 
    Details
    ISSN: 1434-3916
    Keywords: Key words Spondylodiscitis ; Magnetic resonance imaging ; Computed tomography ; Diagnostic algorithm ; Therapeutic algorithm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Fifty-nine patients with spondylodiscitis (SD) of the thoracic and/or lumbar spine were followed-up clinically and radiologically [X-ray, computed tomography (CT), magnetic resonance imaging (MRI)] over a mean time of 2.2 years (1–6.5 years). All patients without abscess formation (n = 35) were treated conservatively. Out of the group with abscess formation (n = 24) 6 patients were also treated conservatively, 11 were drained under CT control and 7 were operated. At time of diagnosis, “signs of florid inflammation” were seen in 60% of the roentgenograms, in 93% of the CTs and in all of the MRIs. The sensitivity to differentiate between SD with and without abscess formation was 85% by MRI and 69% by CT. “Signs of regressive inflammation” and “signs of increasing osseous consolidation”, essential facts for starting remobilization, could first be seen using CT 6 weeks after onset of therapy. Using MRI these signs were seen with a considerable delay at 12 weeks. Clinically, only 3 of the 59 analyzed patients developed recurrent SD. In conclusion, MRI is the radiological method of choice for establishing the diagnosis of SD, in particular with regard to differentiating between cases with and without abscess formations. In contrast, CT is superior for performing success control after treatment. Therapeutically, conservative, minimal-invasive and operative procedures are not rival but rather complementary.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004020050457
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  • 77
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    Electronic Resource
    Gliomas of the optic nerve: histological, immunohistochemical (MIB-1 and p53), and MRI analysis (2000)
    Springer
    Acta neuropathologica 99 (2000), S. 563-570 
    Details
    ISSN: 1432-0533
    Keywords: Key words Ki-67 labeling index ; Magnetic resonance imaging ; Optic nerve glioma ; p53 ; Pilocytic ¶astrocytoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Gliomas of the optic nerve, although typically of pilocytic (WHO grade I) histology, can present within the spectrum of astrocytic neoplasia including glioblastoma (WHO grade IV). In certain cases, histologic features alone make the distinction between pilocytic and diffuse astrocytomas difficult. We reviewed 22 cases of optic nerve gliomas, 19 of which were pilocytic astrocytomas (PA), and 3 of which were diffuse, non-pilocytic astrocytomas. The cases were evaluated for their clinical course, radiographic appearance, histologic grade, and proliferation indices as detected by MIB-1 (Ki-67) and p53 antibodies. Of the 19 PA, 14 showed no tumor growth by magnetic resonance imaging, and had Ki-67 and p53 labeling indices (LI) of 〈 1%. The other 5 PA exhibited aggressive behavior manifest by marked diffuse infiltrative tumor growth causing death in 2 patients, 1 of whom was diagnosed with neurofibromatosis type 1 (immunoperoxidase and radiographs not available), and marked local growth with an average time to growth of 39.3 months, a Ki-67 LI of 2–3%, and a p53 LI of 〈 1% in three others. Three of the five aggressive PA histologically demonstrated a finely reticulated pattern, a pattern that appears as an exaggeration or expansion of the normal neuroglia of the optic nerve, and may simulate a diffuse low-grade astrocytoma. Two demonstrated the coarsely reticulated pattern, with the biphasic and microcystic pattern typical of PA. Three diffuse astrocytomas (2 anaplastic astrocytomas and 1 glioblastoma) originated clinically and radiographically from the optic nerve, and revealed a Ki-67 LI of 2–12%, a p53 LI of 2–8%, and an average time to growth of 8 months. We conclude that the majority of PA of the optic nerve are non-aggressive, stabilize radiographically, and have Ki-67 and p53 LI 〈 1%. However, a subpopulation of PA has a propensity for aggressive behavior, and are identified by a Ki-67 LI of 2–3% and a p53 LI of 〈 1%. Diffuse astrocytomas have both Ki-67 and p53 LI 〉 2%. Thus, in cases of aggressive optic nerve tumors in which the histologic review of biopsy material cannot confidently confirm the diagnosis of pilocytic or diffuse fibrillary glioma, a p53 LI of 〉 1% appears to favor the diagnosis of diffuse astrocytoma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010051161
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  • 78
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    Electronic Resource
    Acute myelofibrosis: multifocal bone marrow infiltration detected by scintigraphy and magnetic resonance imaging (2000)
    Springer
    Annals of hematology 79 (2000), S. 275-278 
    Details
    ISSN: 1432-0584
    Keywords: Key words Acute myelofibrosis ; Acute megakaryoblastic leukemia ; Scintigraphy ; Magnetic resonance imaging ; Interferon gamma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Acute myelofibrosis is a rare, malignant hematological disorder of unknown etiology with an inevitably fatal outcome. Here we present the study of a 63-year-old Caucasian man with acute onset of pancytopenia. Repeated bone marrow biopsies showed dense fibrosis and hypoplastic hematopoiesis raising various differential diagnoses of malignant and nonmalignant conditions. Bone marrow scintigraphy and magnetic resonance imaging (MRI) showed areas suggesting neoplastic infiltration, mainly in both femurs and tibias. Histological examination of a surgical biopsy of the left tibia revealed acute megakaryoblastic leukemia. As the patient refused polychemotherapy, therapy with interferon gamma was initiated but discontinued prematurely because of intolerable side effects. The presented case therefore suggests that the combination of bone marrow scintigraphy and MRI is a valuable diagnostic tool in patients presenting with myelofibrosis of unknown origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002770050593
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  • 79
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    Electronic Resource
    Functional organization of the human masseter muscle (2000)
    Springer
    Surgical and radiologic anatomy 22 (2000), S. 181-190 
    Details
    ISSN: 1279-8517
    Keywords: Masseter muscle ; Architecture ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The authors carried out an anatomic and magnetic resonance imaging study of the architecture of the elevator muscles of the mandible in 169 cadavers. The aim of this study was to define the architectural organization of the human masseter muscle, temporalis and pterygoid muscles. Layered dissections and anatomic sections in different spatial planes showed that the masseter muscle exhibited a typical pennate structure consisting of a succession of alternating musculoaponeurotic layers. The muscle had three well-differentiated parts the superficial, intermediate and deep masseter muscles. The same pattern was constantly found 1) for the superficial masseter, two alternate musculoaponeurotic layers oriented at 60∘ in relation to the plane of occlusion, 2) for the intermediate masseter, a single musculo-aponeurotic layer oriented at 90∘ in relation to the occlusal plane, 3) for the deep masseter, three musculoaponeurotic layers whose general orientation was at 90∘ for the bounding layers and 110∘ for the intermediate layer. The MRI study confirmed the reality of this architectural arrangement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00276-000-0181-5
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  • 80
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    Electronic Resource
    Cortical malformations: a frequent cause of epilepsy in children (2000)
    Springer
    European journal of pediatrics 159 (2000), S. 555-562 
    Details
    ISSN: 1432-1076
    Keywords: Key words Epilepsy ; Cortical malformations ; Migration disorders ; Magnetic resonance imaging ; Brain development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In this review, a simplified scheme for classification of cortical malformations is introduced and illustrated based on the work of Barkovich et al. [8]. Detailed MRI studies identify cortical malformations as a major cause of epilepsy in children. Two aspects that are becoming increasingly important for the paediatrician are emphasised. First, knowledge of the genetic background of cortical malformations is necessary for appropriate genetic counselling. Although the majority of cortical malformations occur sporadically, recent studies have shown a familial pattern in specific epilepsy syndromes associated with cortical malformations. Second, the epilepsy becomes refractory to the common anti-epileptic drugs in many patients with cortical malformations so that epilepsy surgery should be considered. In this respect, the paediatrician can play a pivotal role in referring candidate patients for further specialised assessment. Conclusion The input of the paediatrician will become crucial to link clinical, genetic and neuro-imaging data in children with the great variety of possible cortical malformations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004310000452
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  • 81
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    Adult care in phenylketonuria and hyperphenylalaninaemia: the relevance of neurological abnormalities (2000)
    Springer
    European journal of pediatrics 159 (2000), S. S114 
    Details
    ISSN: 1432-1076
    Keywords: Key words Dietary therapy ; Magnetic resonance imaging ; Neurology ; Pathology ; Phenylketonuria ; AbbreviationsHPA hyperphenylalaninaemia ; 1H-MRS proton magnetic resonance spectroscopy ; Phe phenylalanine ; PKU phenylketonuria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Neurological abnormalities in phenylketonuria were described before dietary treatment became possible. These included tremor, clumsiness, epilepsy, spastic paraparesis and occasionally extrapyramidal features. Neurological deterioration after childhood was recognised. Patients with neurological deterioration described recently have been late diagnosed or intellectually impaired or both. No early diagnosed patient who was well treated and of good intellectual outcome has yet shown neurological deterioration after stopping diet but it may happen. Conclusion The fascinating links between pathology, magnetic resonance imaging appearances, magnetic resonance spectroscopy results and clinical features are not yet clearly understood. Patients must understand the possible risks of stopping diet and make their choice. All patients need help, support and follow-up regardless of the choices they make over continuing diet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00014373
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  • 82
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    Electronic Resource
    Recurrence of non-Hodgkin's lymphoma isolated to the right masticator and left psoas muscles (2000)
    Springer
    European radiology 10 (2000), S. 841-843 
    Details
    ISSN: 1432-1084
    Keywords: Key words: Lymphoma ; Magnetic resonance imaging ; Skeletal muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. We present the clinical and magnetic resonance imaging findings of a patient who, following treatment for pancreatic non-Hodgkin's lymphoma (NHL), relapsed with apparently isolated involvement of the right masticator space and left psoas muscles. Non-Hodgkin's lymphoma arising from the masticator space muscles is very rare. In addition, simultaneous lymphomatous involvement of multiple discrete skeletal muscle sites, in the absence of disease elsewhere, has previously only been reported in the limb or limb girdle muscles. Lymphoma should be considered as a cause of isolated enlarged skeletal muscles, even when involving such distant sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300051015
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  • 83
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    Electronic Resource
    MRI demonstration of intracerebral cryptococcal granuloma (2000)
    Springer
    Neuroradiology 42 (2000), S. 30-33 
    Details
    ISSN: 1432-1920
    Keywords: Key words Granuloma cryptococcal ; Magnetic resonance imaging ; Pulse sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report an intracerebral cryptococcal granuloma in a patient who presented with recent memory disturbance and deteriorating mental status followed by temporary loss of consciousness. To our knowledge, this is the first reported case of an intracerebral cryptococcal granuloma examined by a combination of conventional MRI, fluid-attenuated inversion-recovery and diffusion-weighted imaging and in which the surgical specimen was analysed histochemically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050006
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  • 84
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    Electronic Resource
    MRI of intracranial toxoplasmosis after bone marrow transplantation (2000)
    Springer
    Neuroradiology 42 (2000), S. 14-18 
    Details
    ISSN: 1432-1920
    Keywords: Key words Bone marrow, transplantation ; Toxoplasmosis, cerebral ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Toxoplasma encephalitis was confirmed by biopsy in three patients with bone marrow (BMT) or peripheral blood stem-cell transplantation (PBSCT). All had MRI before antimicrobial therapy. The intensity of contrast enhancement was very variable. One patient had one large, moderately enhancing cerebral lesion and several smaller almost nonenhancing lesions. The second had small nodular and haemorrhagic lesions without any enhancement. The third had late cerebral toxoplasmosis and showed multiple lesions with marked contrast enhancement. The moderate or absent contrast enhancement in the two patients in the early phase of cerebral toxoplasmosis may be related to a poor immunological response, with a low white blood cell count in at least one patient. Both received higher doses of prednisone than the patient with late infection, leading to a reduced inflammatory response. In patients with a low leukocyte count and/or high doses of immunosuppressive therapy, typical contrast enhancement may be absent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050003
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  • 85
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    Electronic Resource
    Cranial MRI in the Nijmegen breakage syndrome (2000)
    Springer
    Neuroradiology 42 (2000), S. 43-47 
    Details
    ISSN: 1432-1920
    Keywords: Key words Nijmegen breakage syndrome ; Anomalies of brain ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We present the results ¶of MRI examinations in ten patients with documented Nijmegen ¶breakage syndrome (NBS), aged 1.75–19 years. T1-, Proton-Density- and T2-weighted spin-echo sequences were performed in three planes. All patients showed microcephaly with decreased size of the frontal lobes and narrow frontal horns. In four patients agenesis of the posterior part of the corpus callosum was found, with colpocephaly and temporal horns dilatation. In one patient callosal hypoplasia was accompanied by abnormal cerebrospinal fluid spaces and wide cerebral cortex, suspicious of pachygyria. Sinusitis was present in all ten patients, as a result of primary immunodeficiency. As in ataxia teleangiectasia and other breakage syndromes, patients with NBS show an inherited susceptibility to malignancy and hypersensitivity to X- and γ-radiation. CT is therefore contraindicated in these patients and MRI should be the method of choice for diagnostic imaging.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050011
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  • 86
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    Electronic Resource
    Dermal sinus with dermoid cyst in the upper cervical spine: case note (2000)
    Springer
    Neuroradiology 42 (2000), S. 51-53 
    Details
    ISSN: 1432-1920
    Keywords: Key words Sinus dermal ; Cyst dermoid ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We describe a 5 year-old girl who had a skin dimple of the back of her upper neck. MRI showed a dermal sinus tract in the upper cervical spine, associated with an intramedullary dermoid cyst at C 2–3, and spina bifida. A laminectomy was performed, the dermoid cyst and the sinus tract were completely removed. This congenital complex is very rare.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050013
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  • 87
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    Electronic Resource
    MRI T-staging of laryngeal tumours: role of contrast medium (2000)
    Springer
    Neuroradiology 42 (2000), S. 66-71 
    Details
    ISSN: 1432-1920
    Keywords: Key words Larynx, tumours ; Magnetic resonance imaging ; Contrast medium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Our aim was to evaluate the relative diagnostic accuracy of MRI without contrast medium and MRI before and after contrast medium in the assessment of T-staging of laryngeal tumours. We studied 25 men (mean age 51.8, range 41–61) with laryngeal squamous cell carcinomas, using Spin-echo (SE) T1-weighted and fast SE T2-weighted sequences. The T1-weighted sequences were then repeated after gadolinium-diethylene-triaminepenta-acetic acid (Gd DTPA) 0.1 ml/kg. All patients then underwent biopsy and surgery. Two radiologists independently assessed the anonymised images by filling-out two multiple-choice forms, one for each technique, at a 2 week interval. The forms included a judgement concerning tumour identification and infiltration of the anterior commissure, supraglottic region, arytenoid cartilage, Morgagni's ventricle, paraglottic space, thyroid and cricoid cartilages, thyro-hyo-epiglottic space, vocal cords, subglottic region, and epiglottis. Similar forms were filled out by the surgeon and the pathologist after surgery. The sensitivity, specificity and diagnostic accuracy of MRI were unaffected by the use of contrast medium. Since it did not provide additional staging information, its continued routine use in these cases is not justified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050017
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  • 88
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    Electronic Resource
    Bilateral thalamic glioma: case report (2000)
    Springer
    Neuroradiology 42 (2000), S. 732-734 
    Details
    ISSN: 1432-1920
    Keywords: Key words Glioma, thalamic, bilateral ; Magnetic resonance imaging ; Magnetic resonance spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a 63-year-old man who had a rare bilateral thalamic glioma. He complained of difficulty with calculations and had mental deterioration. T1-weighted images revealed bilateral thalamic swelling with homogeneous low signal and no contrast enhancement. The tumour, showing decrease of N-acetylaspartate and the presence of lactate on magnetic resonance spectroscopy, was diagnosed as an astrocytoma by stereotactic biopsy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340000380
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  • 89
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    Electronic Resource
    Primary central nervous system immunocytoma: MRI and spectroscopy (2000)
    Springer
    Neuroradiology 42 (2000), S. 738-741 
    Details
    ISSN: 1432-1920
    Keywords: Key words Lymphoma ; Central nervous system ; Immunocytoma, cerebral ; Magnetic resonance imaging ; Magnetic resonance spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report on a young woman with a primary cerebral immunocytoma. Most primary cerebral nervous system lymphomas (PCNSL) are highly malignant undifferentiated B-cell tumours, there are few data on the clinical course, MRI and spectroscopy findings of this rare PCNSL subtype. MRI revealed a radially enhancing tumour with mild perifocal oedema. MR spectroscopy indicated low cell turnover. Slow clinical progression, no significant changes with treatment, and imaging findings were consistent with a low-grade malignant tumour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340000392
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  • 90
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    Electronic Resource
    MRI in tick-borne encephalitis (2000)
    Springer
    Neuroradiology 42 (2000), S. 753-755 
    Details
    ISSN: 1432-1920
    Keywords: Key words Encephalitis, tick-borne ; Magnetic resonance imaging ; Basal ganglia ; Thalamus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The tick-borne encephalitis (TBE) virus gives rise to epidemic encephalitis. Mild forms usually manifest as influenza-like episodes or are clinically silent. MRI is usually normal in TBE. We describe severe TBE in a patient who presented with fever and altered mental status after a tick bite and a specific antibody response to TBE. MRI revealed pronounced signal abnormalities in the basal ganglia and thalamus, without contrast enhancement. These findings coincide well with neuropathological studies of severe nerve cell degeneration with inflammatory cell infiltrates, neuronophagia and reactive astrocytosis in the deep grey matter. We review the literature and discuss the relevant differential diagnosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340000396
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  • 91
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    Electronic Resource
    Classification of acquired lesions of the corpus callosum with MRI (2000)
    Springer
    Neuroradiology 42 (2000), S. 795-802 
    Details
    ISSN: 1432-1920
    Keywords: Key words Corpus callosum ; Ischaemia ; Demyelination ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract MRI has facilitated diagnostic assessment of the corpus callosum. Diagnostic classification of solitary or multiple lesions of the corpus callosum has not attracted much attention, although signal abnormalities are not uncommon. Our aim was to identify characteristic imaging features of lesions frequently encountered in practice. We reviewed the case histories of 59 patients with lesions shown on MRI. The nature of the lesions was based on clinical features and/or long term follow-up (ischaemic 20, Virchow-Robin spaces 3, diffuse axonal injury 7, multiple sclerosis 11, hydrocephalus 5, acute disseminated encephalomyelitis 5, Marchiafava-Bignami disease 4, lymphoma 2, glioblastoma hamartoma each 1). The location in the sagittal plane, the relationship to the borders of the corpus callosum and midline and the size were documented. The 20 ischaemic lesions were asymmetrical but adjacent to the midline; the latter was involved in new or large lesions. Diffuse axonal injury commonly resulted in large lesions, which tended to be asymmetrical; the midline and borders of the corpus callosum were always involved. Lesions in MS were small, at the lower border of the corpus callosum next to the septum pellucidum, and crossed the midline asymmetrically. Acute disseminated encephalomyelitis and the other perivenous inflammatory diseases caused relatively large, asymmetrical lesions. Hydrocephalus resulted in lesions of the upper part of the corpus callosum, and mostly in its posterior two thirds; they were found in the midline. Lesions in Marchiafava-Bignami disease were large, often symmetrically in the midline in the splenium and did not reach the edge of the corpus callosum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340000430
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  • 92
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    Neuroradiological history: Sir Joseph Larmor and the basis of MRI physics (2000)
    Springer
    Neuroradiology 42 (2000), S. 852-855 
    Details
    ISSN: 1432-1920
    Keywords: Key words Larmor ; Joseph ; Magnetic resonance imaging ; Neurology history
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The origin of many of the eponymous terms in modern medicine is unknown to many people who utter them daily. As a contribution to understanding the historical background of MRI, we provide a brief account of the life and work of Joseph Larmor, the Irish scientist, whose name is frequently used by chemists, physicists and radiologists alike.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340000400
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  • 93
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    Electronic Resource
    Gadolinium-myelocisternography for cerebrospinal fluid rhinorrhoea (2000)
    Springer
    Neuroradiology 42 (2000), S. 874-880 
    Details
    ISSN: 1432-1920
    Keywords: Key words Gadolinium-containing contrast medium ; Myelocisternography ; Cerebrospinal fluid leakage ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Knowledge of the exact site of leakage of cerebrospinal fluid CSF leakage is important for planning surgery. We report our experience with myelocisternography with Gd-DTPA. We decided that intrathecal use of this contrast medium was justified in selected cases when other techniques have failed. After we had given detailed information to four patients with CSF leakage, they underwent five examinations. The images were interpreted by comparing those before and after injection. In all cases the contrast medium arrived at the basal cisterns, giving high contrast against adjacent structures. All patients tolerated the examination without complications or any indication of side effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340000485
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  • 94
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    Idiopathic granulomatous hypophysitis: are there reliable, constant radiological and clinical diagnostic criterias? (2000)
    Springer
    Neuroradiology 42 (2000), S. 890-894 
    Details
    ISSN: 1432-1920
    Keywords: Key words Pituitary ; Hypophysitis, granulomatous ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Idiopathic granulomatous hypophysitis is a rare inflammatory disease of unknown aetiology; few cases are reported. We review the clinical presentation and radiological characteristics of these cases and our own experience with three new surgical cases, to determine diagnostic criteria. MRI of three cases revealed sellar lesions extending into the chiasmatic cistern. Their shape varied, from dumbbell to spherical and elliptical. All were isointense with the brain on T1-weighted images and gave heterogeneously high signal on T2-weighted images. Contrast enhancement was homogeneous in one case and heterogeneous in another. The pituitary stalk could not be identified. There was no dural enhancement. The sphenoid sinus mucosa was thickened in two cases and normal in one.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340000481
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  • 95
    Electronic Resource
    Electronic Resource
    A case of ochronosis: MRI of the lumbar spine (2000)
    Springer
    Neuroradiology 42 (2000), S. 905-907 
    Details
    ISSN: 1432-1920
    Keywords: Key words Alkaptonuria ; Ochronosis ; Spine ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We present the MRI features of the lumbar spine in a patient with ochronosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340000428
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  • 96
    Electronic Resource
    Electronic Resource
    Primary malignant lymphoma of the maxillary sinus: CT and MRI (2000)
    Springer
    Neuroradiology 42 (2000), S. 285-289 
    Details
    ISSN: 1432-1920
    Keywords: Key words Lymphoma ; malignant ; Sinus ; maxillary ; Magnetic resonance imaging ; Computed tomography.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We reviewed the CT and MRI of seven patients with primary malignant lymphoma of the maxillary sinus to find if there are characteristic imaging findings suggestive of the disease. The images were analysed for appearance, size, signal, internal characteristics, extent of tumour, bone change and lymph node enlargement. In two patients, the tumour first presented with mucosal thickening. In the remaining five, the tumours were an expansile mass 4–6 cm in diameter at the time of detection. Although it was difficult to distinguish tumour from mucosa or obstructed fluid on CT, T2-weighted MRI enabled us to separate tumour from normal mucosa or fluid. In two patients, the tumours were heterogeneous. Calcification and haemorrhage were observed in one patient. Periantral soft-tissue infiltration was always present, even when tumour appeared as slight mucosal thickening. Posterior extension was seen in all patients. Permeative and lytic bone destruction accompanied most cases of periantral soft-tissue infiltration; mixed destruction and sclerosis was also observed. Mucosal thickening with periantral soft-tissue infiltration may suggest malignant lymphoma of the maxillary sinus in its early form. Various types of bone change may accompany the periantral soft-tissue infiltration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050887
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  • 97
    Electronic Resource
    Electronic Resource
    Hippocampal malrotation with normal corpus callosum: a new entity? (2000)
    Springer
    Neuroradiology 42 (2000), S. 339-345 
    Details
    ISSN: 1432-1920
    Keywords: Key words Brain, development ; Hippocampus ; Magnetic resonance imaging ; Epilepsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Among 527 MRI examinations of patients with a suspicion of epilepsy in 5 years, we found 32 cases of hippocampal malrotation (HIMAL). The characteristic features are: incomplete inversion of the hippocampus with and abnormally round shape; unilateral involvement of the whole hippocampus; normal signal intensity and size; blurred internal structure; an abnormal angle of collateral sulcus; abnormal position and size of the fornix; normal size of the temporal lobe; enlargement and particular configuration of the temporal horn, typical of corpus callosum agenesis; and a normal corpus callosum. In 7 cases (22 %) HIMAL occurred together with developmental disorders. It was predominantly seen in men. The clinical features were varied. Based on some MRI features, the presence of developmental disorders, the male predominance, the frequently positive family history, and a review of the literature, we think HIMAL may be the consequence of a mild hemisphere developmental disorder. It is probably not the basic cause of epilepsy in such varied clinical setting, but may be a sign of a developmental disorder and can help in selecting patients for more meticulous investigation. It also may give some new understanding of brain development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050895
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  • 98
    Electronic Resource
    Electronic Resource
    MRI of orbital schwannomas (2000)
    Springer
    Neuroradiology 42 (2000), S. 466-468 
    Details
    ISSN: 1432-1920
    Keywords: Key words Orbit ; Schwannoma ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The literature on MRI of orbital schwannomas is limited. The appearances in three patients with an orbital schwannoma were reviewed. A superior orbitotomy through a subfrontal craniotomy revealed a schwannoma in all cases. MRI characteristics of very low signal on T 1-weighted images and homogeneous postcontrast enhancement may be helpful for differentiating schwannomas from other intraconal masses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340000296
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  • 99
    Electronic Resource
    Electronic Resource
    Dural enhancement in pituitary macroadenomas (2000)
    Springer
    Neuroradiology 42 (2000), S. 505-508 
    Details
    ISSN: 1432-1920
    Keywords: Key words Meninges ; Adenoma ; pituitary ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We describe the normal dural enhancement patterns of the sellar region and determine whether the duramater is affected by pituitary macroadenomas. Dural enhancement appeared to be usually abnormal in 20 patients with pituitary macroadenoma compared with 20 control patients, mainly at the planum sphenoidale and carotid sulcus. However dural changes are subtle and their recognition requires knowledge of the normal enhancement patterns. Dural changes, reported in a variety of inflammatory and infectious dural diseases and after surgery, are not specific and may be also seen in pituitary macroadenomas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340000346
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  • 100
    Electronic Resource
    Electronic Resource
    Virtual endoscopy of the inner ear and the auditory canal (2000)
    Springer
    Neuroradiology 42 (2000), S. 543-547 
    Details
    ISSN: 1432-1920
    Keywords: Key words Inner ear ; Virtual endoscopy ; Volume rendering ; Computed tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To assess the role of virtual endoscopy (VE) in the examination of intracisternal structures and of the inner ear, we studied the anatomy of the labyrinth and internal auditory canal using the original CT slices and VE on the unaffected side in three female and three male patients, age range 3–46 years, with contralateral retrocochlear hearing loss. We also examined seven patients with different pathological findings. VE was performed using an advanced postprocessing program with high- resolution 3D data sets of CT (1–1.5 mm thickness, pitch 1.25) and MRI-CISS-3D (constructive interference in steady state) images of the basal cisterns (1.5 T, slice thickness 0.7–1 mm). VE provides an endoscopic-like view from a given point within the basal cisterns of vessels and nerves (on MRI) or of the structures of the inner ear (on CT). The complex anatomy and pathological changes in the inner ear can be faithfully shown. The main advantage is not basic diagnostic information but demonstration of topographically complex situations, such as the canalicular system of the inner ear, for discussion, preoperative planning and teaching.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340000329
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