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  • 2000-2004
  • 1995-1999  (327)
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  • 1920-1924
  • 1999  (327)
  • 1937  (689)
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  • ddc:000
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  • 2000-2004
  • 1995-1999  (327)
  • 1935-1939  (689)
  • 1920-1924
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  • 1
    Publication Date: 2020-03-11
    Description: Im Kooperativen Bibliotheksverbund Berlin-Brandenburg (KOBV) wird die verteilte Suche in heterogenen Datenbank mit einer integrierten Dublettenerkennung und -zusammenfuehrung realisiert. Beschrieben werden die einzelnen attributspezifischen Normierungsschritte, die dem eigentlichen Vergleich (MATCH) zweier Datensätze vorangehen.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 2
    Publication Date: 2014-02-26
    Description: In molecular dynamics applications there is a growing interest in mixed quantum-classical models. The {\em quantum-classical Liouville equation} (QCL) describes most atoms of the molecular system under consideration by means of classical phase space density but an important, small portion of the system by means of quantum mechanics. The QCL is derived from the full quantum dynamical (QD) description by applying the Wigner transform to the classical part'' of the system only. We discuss the conditions under which the QCL model approximates the full QD evolution of the system. First, analysis of the asymptotic properties of the Wigner transform shows that solving the QCL yields a first order approximation of full quantum dynamics. Second, we discuss the adiabatic limit of the QCL. This discussion shows that the QCL solutions may be interpretated as classical phase space densities, at least near the adiabatic limit. Third, it is demonstrated that the QCL yields good approximations of {\em non-adiabatic quantum effects,} especially near so-called {\em avoided crossings} where most quantum-classical models fail.
    Keywords: ddc:000
    Language: English
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  • 3
    Publication Date: 2020-11-13
    Description: Dieser Artikel gibt eine allgemeinverständliche Einführung in die spezielle Problematik kombinatorischer Online-Problem am Beispiel der Fahrstuhlsteuerung.
    Keywords: ddc:000
    Language: German
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  • 4
    Publication Date: 2020-08-05
    Description: Wir geben eine Einführung in die Mathematik von und mit Wegen. Nicht auf dem kürzesten, aber auf einem hoffentlich kurzweiligen Weg!
    Keywords: ddc:000
    Language: German
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  • 5
    Publication Date: 2021-02-01
    Description: Mean-variance portfolio analysis provided the first quantitative treatment of the tradeoff between profit and risk. We investigate in detail the interplay between objective and constraints in a number of single-period variants, including semi-variance models. Particular emphasis is laid on avoiding the penalization of overperformance. The results are then used as building blocks in the development and theoretical analysis of multi-period models based on scenario trees. A key property is the possibility to remove surplus money in future decisions, yielding approximate downside risk minimization.
    Keywords: ddc:000
    Language: English
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  • 6
    Publication Date: 2014-02-26
    Description: The paper compares computational aspects of four approaches to compute conservation laws of single differential equations or systems of them, ODEs and PDEs. The only restriction, required by two of the four corresponding computer algebra programs, is that each DE has to be solvable for a leading derivative. Extra constraints may be given. Examples of new conservation laws include non-polynomial expressions, an explicit variable dependence and conservation laws involving arbitrary functions. Examples involve the following equations: Ito, Liouville, Burgers, Kadomtsev-Petviashvili, Karney-Sen-Chu-Verheest, Boussinesq, Tzetzeica, Benney.
    Keywords: ddc:000
    Language: English
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  • 7
    Publication Date: 2014-02-26
    Description: Recently, a novel concept for the computation of essential features of the dynamics of Hamiltonian systems (such as molecular dynamics) has been proposed. The realization of this concept had been based on subdivision techniques applied to the Frobenius--Perron operator for the dynamical system. The present paper suggests an alternative but related concept that merges the conceptual advantages of the dynamical systems approach with the appropriate statistical physics framework. This approach allows to define the phrase ``conformation'' in terms of the dynamical behavior of the molecular system and to characterize the dynamical stability of conformations. In a first step, the frequency of conformational changes is characterized in statistical terms leading to the definition of some Markov operator $T$ that describes the corresponding transition probabilities within the canonical ensemble. In a second step, a discretization of $T$ via specific hybrid Monte Carlo techniques is shown to lead to a stochastic matrix $P$. With these theoretical preparations, an identification algorithm for conformations is applicable. It is demonstrated that the discretization of $T$ can be restricted to few essential degrees of freedom so that the combinatorial explosion of discretization boxes is prevented and biomolecular systems can be attacked. Numerical results for the n-pentane molecule and the triribonucleotide adenylyl\emph{(3'-5')}cytidylyl\emph{(3'-5')}cytidin are given and interpreted.
    Keywords: ddc:000
    Language: English
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  • 8
    Publication Date: 2021-03-16
    Description: In KOBV we offer the user an efficient tool for searching regional and worldwide accessible library catalogues (KOBV search engine). Search is performed by a distributed Z39.50 retrieval and an index based quicksearch. Due to the number of catalogues, result sets may contain a significant amount of duplicate records. Therefore we integrate a de-duplication procedure into KOBV search engine. It is part of the distributed search and the KOBV quicksearch as well. Main goals are the presentation of uniform retrieval results, the preservation of retrieval quality and cutting off redundant information. At least we keep an eye on efficiency. De-duplication is fully parametrizable, so that settings can be changed easily on line.
    Keywords: ddc:000
    Language: English
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  • 9
    Publication Date: 2014-02-26
    Description: A cascadic multigrid (CMG) method for elliptic problems with strong material jumps is proposed and analyzed. Non--matching grids at interfaces between subdomains are allowed and treated by mortar elements. The arising saddle point problems are solved by a subspace confined conjugate gradient method as smoother for the CMG. Details of algorithmic realization including adaptivity are elaborated. Numerical results illustrate the efficiency of this CMG algorithm.
    Keywords: ddc:000
    Language: English
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  • 10
    Publication Date: 2020-11-13
    Description: In a large distribution center of Herlitz AG, Berlin, we invesigated the elevator subsystem of the fully automated pallet transportation system. Each elevator may carry one pallet and has to serve eight levels. The goal is to minimize the average resp.\ the maximum flow time. The variants of this elevator control problem have been subject of recent theoretical research and are known as online-dial-a-ride problems. In this paper we investigate several online algorithms for several versions of online-dial-a-ride problems by means of a simulation program, developed on the basis of the simulation library AMSEL. We draw statistics from samples of randomly generated data providing for different load situations. Moreover, we provide preliminary studies with real production data for a system of five elevators connected by a conveyor circuit, as can be found at the Herlitz plant. We show which algorithms are best under certain load situations and which lead to break downs under particular circumstances.
    Keywords: ddc:000
    Language: English
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  • 11
    Publication Date: 2014-02-26
    Description: We present an algebraic multigrid preconditioner which uses only the graphs of system matrices. Some elementary coarsening rules are stated, from which an advancing front algorithm for the selection of coarse grid nodes is derived. This technique can be applied to linear Lagrange-type finite element discretizations; for higher-order elements an extension of the multigrid algorithm is provided. Both two- and three-dimensional second order elliptic problems can be handled. Numerical experiments show that the resulting convergence acceleration is comparable to classical geometric multigrid.
    Keywords: ddc:000
    Language: English
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  • 12
    Publication Date: 2014-02-26
    Description: \\{\bf Zusammenfassung: }Diese Diplomarbeit beschreibt ein verteiltes Bibliotheks-Informationssystem für bibliographische Datenbanken im Internet. Der Name des Systems ist ZACK. Der Benutzer kann mit ZACK in einer oder mehreren bibliographischen Datenbanken nach einem Dokument suchen und die Treffer in die eigene lokale Datenbank übernehmen. Mit der Übernahme der Datensätze aus einer fremden Datenbank wird die Erfassung neuer Dokumente wesentlich erleichtert, da die Eigenkatalogisierung auf ein Minimum beschränkt werden kann. Es wird doppelte Arbeit vermieden, und die Datensätze haben eine gleichbleibend hohe Qualität. Bei der verteilten Suche mit ZACK wird parallel in mehreren Datenbanken gesucht. Dubletten werden als solche erkannt. Dem Benutzer wird eine übersichtliche Kurztrefferliste ohne doppelte Einträge angeboten. Er kann dann selbst entscheiden, aus welcher Datenbank er die Datensätze übernimmt. Die verteilte Suche hat in der Praxis eine deutlich bessere Trefferquote gebracht als die Suche in nur einer Datenbank. Dabei bleibt die Antwortzeit in einem für den Benutzer akzeptablen Rahmen. Die Kurztrefferliste wird durch die Dublettenkontrolle kürzer und übersichtlicher. English Title: A Distributed Library Information System on the Basis of the Z39.50 Protocol This diploma thesis desribes a distributed library information system for bibliographic databases in the Internet. The name of the system is ZACK. With ZACK the user is able to search for a particular document in several databases and to include the matches in his/her own local database. The inclusion of data records from an external database makes the capture of new documents much easier, as internal cataloging is reduced to a minimum. Double work is eliminated and a continuously high quality of data record is ensured. The distributed search by means of ZACK is carried out in several databases in parallel. Duplicates are recognized; and a short list of matches without double entries is offered. The user can then decide for himself from which database to include data records. In practice, a distributed search has produced far better results than the search in one particular database. Response times are within an acceptable limit for the user. The short list of hits is made clearer and more concise by the duplicate check. The diploma thesis is also available in PDF, HTML, and ASCII format: http://wolfram.schneider.org/lv/diplom/ .
    Keywords: ddc:000
    Language: German
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  • 13
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    Publication Date: 2014-02-26
    Description: Flavone and the flavylium ion have been studied at Hartree-Fock, M{\o}ller-Plesset and B3LYP hybrid density functional level to determine the structures and barriers to internal rotation. Both molecules have a high perpendicular barrier about the single bond connecting the phenyl ring with the benzopyrone and benzopyrylium ring, respectively. In contrast to biphenyl both molecules have low coplanar barriers. B3LYP overestimates the perpendicular barrier heights compared to other methods. The dependence of the population and orbital energies on the torsion has been investigated and the structures of both flavonoids have been estimated by means of a reaction field model.
    Keywords: ddc:000
    Language: English
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  • 14
    Publication Date: 2020-03-09
    Description: Das Math-Net ist ein verteiltes Informationssystem f"ur die Mathematik. Es basiert auf den lokalen Informationsangeboten der Fachbereiche, die im Math-Net integriert, nutzerfreundlich aufbereitet und zug"anglich gemacht werden sollen. Das Math-Net ist durch die freiwillige Mitarbeit weiterer Institutionen in Deutschland zu einem flächendeckenden Dienst ausgebaut worden. Die am Projekt beteiligten Institutionen haben die mathematischen Institutionen in ihrer Region beim Aufbau eines qualitativ hochwertigen lokalen Informationsangebotes unterstützt und die Integration der lokalen Informationsangebote in das Math-Net koordiniert.
    Keywords: ddc:000
    Language: German
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  • 15
    Publication Date: 2014-02-26
    Description: The function of many important biomolecules is related to their dynamic properties and their ability to switch between different {\em conformations}, which are understood as {\em almost invariant} or {\em metastable} subsets of the positional state space of the system. Recently, the present authors and their coworkers presented a novel algorithmic scheme for the direct numerical determination of such metastable subsets and the transition probability between them. Although being different in most aspects, this method exploits the same basic idea as {\sc Dellnitz} and {\sc Junge} in their approach to almost invariance in discrete dynamical systems: the almost invariant sets are computed via certain eigenvectors of the Markov operators associated with the dynamical behavior. In the present article we analyze the application of this approach to (high--friction) Langevin models describing the dynamical behavior of molecular systems coupled to a heat bath. We will see that this can be related to theoretical results for (symmetric) semigroups of Markov operators going back to {\sc Davies}. We concentrate on a comparison of our approach in respect to random perturbations of dynamical systems.
    Keywords: ddc:000
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  • 16
    Publication Date: 2014-02-27
    Description: An introductory chapter on Groebner bases is given which also includes new results on the detection of Groebner bases for sparse polynomial systems. Algorithms for the computation of invariants and equivariants for finite groups, compact Lie groups and algebraic groups are presented and efficient implementation and time comparision are discussed. This chapter also inlcudes improvements of the computation of Noether normalisation and Stanley decomposition. These results are applied in symmetric bifurcation theory and equivariant dynamics. As preparation of the investigation of the orbit space reduction three methods are compared for solving symmetric polynomial systems exactly. The method of orbit space reduction is improved by using the Cohen-Macaulayness of the invariant ring and nested Noether normalization. Finally this is applied for a case of mode interaction in the Taylor-Couette problem.
    Keywords: ddc:000
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 17
    Publication Date: 2014-02-26
    Description: A class of sparse polynomial systems is investigated which is defined by a weighted directed graph and a weighted bipartite graph. They arise in the model of mass action kinetics for chemical reaction systems. In this application the number of real positive solutions within a certain affine subspace is of particular interest. We show that the simplest cases are equivalent to binomial systems while in general the solution structure is highly determined by the properties of the two graphs. First we recall results by Feinberg and give rigorous proofs. Secondly, we explain how the graphs determine the Newton polytopes of the system of sparse polynomials and thus determine the solution structure. The results on positive solutions from real algebraic geometry are applied to this particular situation. Examples illustrate the theoretical results.
    Keywords: ddc:000
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  • 18
    Publication Date: 2014-02-26
    Description: We study the improvement of simulations of QCD with dynamical Wilson fermions by combining the Hybrid Monte Carlo algorithm with parallel tempering. As an indicator for decorrelation we use the topological charge.
    Keywords: ddc:000
    Language: English
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  • 19
    Publication Date: 2020-03-09
    Description: We describe a novel method for continuously transforming two triangulated models of arbitrary topology into each other. Equal global topology for both objects is assumed, extensions for genus changes during metamorphosis are provided. The proposed method addresses the major challenge in 3D metamorphosis, namely specifying the morphing process intuitively, with minimal user interaction and sufficient detail. Corresponding regions and point features are interactively identified. These regions are parametrized automatically and consistently, providing a basis for smooth interpolation. Utilizing suitable 3D interaction techniques a simple and intuitive control over the whole morphing process is offered.
    Keywords: ddc:000
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  • 20
    Publication Date: 2014-02-26
    Description: Our focus is on Maxwell's equations in the low frequency range; two specific applications we aim at are time-stepping schemes for eddy current computations and the stationary double-curl equation for time-harmonic fields. We assume that the computational domain is discretized by triangles or tetrahedrons; for the finite element approximation we choose N\'{e}d\'{e}lec's $H(curl)$-conforming edge elements of the lowest order. For the solution of the arising linear equation systems we devise an algebraic multigrid preconditioner based on a spatial component splitting of the field. Mesh coarsening takes place in an auxiliary subspace, which is constructed with the aid of a nodal vector basis. Within this subspace coarse grids are created by exploiting the matrix graphs. Additionally, we have to cope with the kernel of the $curl$-operator, which comprises a considerable part of the spectral modes on the grid. Fortunately, the kernel modes are accessible via a discrete Helmholtz decomposition of the fields; they are smoothed by additional algebraic multigrid cycles. Numerical experiments are included in order to assess the efficacy of the proposed algorithms.
    Keywords: ddc:000
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  • 21
    Publication Date: 2020-03-09
    Description: Large scale simulations running in metacomputing environments face the problem of efficient file I/O. For efficiency it is desirable to write data locally, distributed across the computing environment, and then to minimize data transfer, i.e.\ reduce remote file access. Both aspects require I/O approaches which differ from existing paradigms. For the data output of distributed simulations, one wants to use fast local parallel I/O for all participating nodes, producing a single distributed logical file, while keeping changes to the simulation code as small as possible. For reading the data file as in postprocessing and file based visualization, one wants to have efficient partial access to remote and distributed files, using a global naming scheme and efficient data caching, and again keeping the changes to the postprocessing code small. However, all available software solutions require the entire data to be staged locally (involving possible data recombination and conversion), or suffer from the performance problems of remote or distributed file systems. In this paper we show how to interface the HDF5 I/O library via its flexible Virtual File Driver layer to the Globus Data Grid. We show, that combining these two toolkits in a suitable way provides us with a new I/O framework, which allows efficient, secure, distributed and parallel file I/O in a metacomputing environment.
    Keywords: ddc:000
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  • 22
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    Publication Date: 2014-02-26
    Description: Although the m-ATSP (or multi traveling salesman problem) is well known for its importance in scheduling and vehicle routing, it has, to the best of our knowledge, never been studied polyhedraly, i.e., it has always been transformed to the standard ATSP. This transformation is valid only if the cost of an arc from node $i$ to node $j$ is the same for all machines. In many practical applications this is not the case, machines produce with different speeds and require different (usually sequence dependent) setup times. We present first results of a polyhedral analysis of the m-ATSP in full generality. For this we exploit the tight relation between the subproblem for one machine and the prize collecting traveling salesman problem. We show that, for $m\ge 3$ machines, all facets of the one machine subproblem also define facets of the m-ATSP polytope. In particular the inequalities corresponding to the subtour elimination constraints in the one machine subproblems are facet defining for m-ATSP for $m\ge 2$ and can be separated in polynomial time. Furthermore, they imply the subtour elimination constraints for the ATSP-problem obtained via the standard transformation for identical machines. In addition, we identify a new class of facet defining inequalities of the one machine subproblem, that are also facet defining for m-ATSP for $m\ge 2$. To illustrate the efficacy of the approach we present numerical results for a scheduling problem with non-identical machines, arising in the production of gift wrap at Herlitz PBS AG.
    Keywords: ddc:000
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  • 23
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    Publication Date: 2014-02-26
    Description: Due to its many applications in control theory, robust optimization, combinatorial optimization and eigenvalue optimization, semidefinite programming had been in wide spread use even before the development of efficient algorithms brought it into the realm of tractability. Today it is one of the basic modeling and optimization tools along with linear and quadratic programming. Our survey is an introduction to semidefinite programming, its duality and complexity theory, its applications and algorithms.
    Keywords: ddc:000
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  • 24
    Publication Date: 2020-11-13
    Description: Im Herbst 1999 ging der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) in Routinebetrieb. In technischer Hinsicht setzt der KOBV auf ein neuartiges, zukunftsweisendes Verbundkonzept, in dem die zentrale Datenbank mit dem Verbundkatalog ersetzt wird durch verteilte Datenbanken und lokale Kataloge, die durch das Netz (Internet) miteinander verbunden sind. Die zentrale Recherchefunktion wird ersetzt durch die KOBV-Suchmaschine. Beschrieben werden die Hintergründe, die zu diesem Konzept geführt haben, die Kriterien, die die Architekturentscheidungen der Software bestimmt haben, sowie die einzelnen realisierten Komponenten.
    Keywords: ddc:000
    Language: German
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  • 25
    Publication Date: 2014-11-10
    Description: Given an affine surjection of polytopes $\pi: P \to Q$, the Generalized Baues Problem asks whether the poset of all proper polyhedral subdivisions of $Q$ which are induced by the map $\pi$ has the homotopy type of a sphere. We extend earlier work of the last two authors on subdivisions of cyclic polytopes to give an affirmative answer to the problem for the natural surjections between cyclic polytopes $\pi: C(n,d') \to C(n,d)$ for all $1 \leq d 〈 d' 〈 n$.
    Keywords: ddc:000
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  • 26
    Publication Date: 2014-11-10
    Description: In 1994, Sturmfels gave a polyhedral version of the Cayley Trick of elimination theory: he established an order-preserving bijection between the posets of \emph{coherent} mixed subdivisions of a Minkowski sum $\mathcal{A}_1+\cdots+\mathcal{A}_r$ of point configurations and of \emph{coherent} polyhedral subdivisions of the associated Cayley embedding $\mathcal{C}(\mathcal{A}_1,\dots,\mathcal{A}_r)$. In this paper we extend this correspondence in a natural way to cover also \emph{non-coherent} subdivisions. As an application, we show that the Cayley Trick combined with results of Santos on subdivisions of Lawrence polytopes provides a new independent proof of the Bohne-Dress Theorem on zonotopal tilings. This application uses a combinatorial characterization of lifting subdivisions, also originally proved by Santos.
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  • 27
    Publication Date: 2014-02-26
    Description: It is well known that the following class of systems of evolution equations \begin{eqnarray} \label{nsgen} \cases{ u_{t}=u_{xx}+F(u,v,u_x,v_x),\cr v_{t}=-v_{xx}+G(u,v,u_x,v_x),\cr} \end{eqnarray} is very rich in integrable cases. The complete classification problem is very difficult. Here we consider only the most interesting (from our opinion) subclass of systems (1). Namely, we consider equations linear in all derivatives of the form \begin{eqnarray} \label{kvazgen} \cases{ u_t = u_{xx} + A_{1}(u,v) u_x + A_{2}(u,v) v_x + A_{0}(u,v)\cr v_t = - v_{xx} + B_{1}(u,v) v_x + B_{2}(u,v) u_x + B_{0}(u,v). \cr} \end{eqnarray} without any restrictions on the functions $A_{i}(u,v), B_{i}(u,v)$.
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  • 28
    Publication Date: 2020-11-13
    Description: In this paper we study algorithms for ``Dial-a-Ride'' transportation problems. In the basic version of the problem we are given transportation jobs between the vertices of a graph and the goal is to find a shortest transportation that serves all the jobs. This problem is known to be NP-hard even on trees. We consider the extension when precedence relations between the jobs with the same source are given. Our results include a polynomial time algorithm on paths and an approximation algorithm on general graphs with a performance of~$9/4$. For trees we improve the performance to~$5/3$.
    Keywords: ddc:000
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  • 29
    Publication Date: 2020-08-05
    Description: In this thesis we study and solve integer programs with block structure, i.\,e., problems that after the removal of certain rows (or columns) of the constraint matrix decompose into independent subproblems. The matrices associated with each subproblem are called blocks and the rows (columns) to be removed linking constraints (columns). Integer programs with block structure come up in a natural way in many real-world applications. The methods that are widely used to tackle integer programs with block structure are decomposition methods. The idea is to decouple the linking constraints (variables) from the problem and treat them at a superordinate level, often called master problem. The resulting residual subordinate problem then decomposes into independent subproblems that often can be solved more efficiently. Decomposition methods now work alternately on the master and subordinate problem and iteratively exchange information to solve the original problem to optimality. In Part I we follow a different approach. We treat the integer programming problem as a whole and keep the linking constraints in the formulation. We consider the associated polyhedra and investigate the polyhedral consequences of the involved linking constraints. The variety and complexity of the new inequalities that come into play is illustrated on three different types of real-world problems. The applications arise in the design of electronic circuits, in telecommunication and production planning. We develop a branch-and-cut algorithm for each of these problems, and our computational results show the benefits and limits of the polyhedral approach to solve these real-world models with block structure. Part II of the thesis deals with general mixed integer programming problems, that is integer programs with no apparent structure in the constraint matrix. We will discuss in Chapter 5 the main ingredients of an LP based branch-and-bound algorithm for the solution of general integer programs. Chapter 6 then asks the question whether general integer programs decompose into certain block structures and investigate whether it is possible to recognize such a structure. The remaining two chapters exploit information about the block structure of an integer program. In Chapter 7 we parallelize parts of the dual simplex algorithm, the method that is commonly used for the solution of the underlying linear programs within a branch-and-cut algorithm. In Chapter 8 we try to detect small blocks in the constraint matrix and to derive new cutting planes that strengthen the integer programming formulation. These inequalities may be associated with the intersection of several knapsack problems. We will see that they significantly improve the quality of the general integer programming solver introduced in Chapter 5.
    Keywords: ddc:000
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 30
    Publication Date: 2014-02-26
    Description: A new seasonal energy storage for thermal solar systems has been developed on the basis of an adsorption-desorption process. Design and optimization of this storage will be supported by numerical simulations of heat and mass transfer with KARDOS. This paper focuses on the unsteady heat transfer during the major operating step of energetic discharge of the storage, which is characterized by conductive heat transfer in the fixed bed and a strong heat source caused by the adsorption enthalpy. Results are interpreted concerning the influence of variations in the parameter set. The method of implementation of the differential equation will be shown as well as the post-processing and gridwriting programs.
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    Language: English
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  • 31
    Publication Date: 2020-11-13
    Description: In this paper, we analyze algorithms for the online dial-a-ride problem with request sets that fulfill a certain worst-case restriction: roughly speaking, a set of requests for the online dial-a-ride problem is reasonable if the requests that come up in a sufficiently large time period can be served in a time period of at most the same length. This new notion is a stability criterion implying that the system is not overloaded. The new concept is used to analyze the online dial-a-ride problem for the minimization of the maximal resp.\ average flow time. Under reasonable load it is possible to distinguish the performance of two particular algorithms for this problem, which seems to be impossible by means of classical competitive analysis.
    Keywords: ddc:000
    Language: English
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  • 32
    Publication Date: 2014-02-27
    Description: The function of many important biomolecules comes from their dynamic properties and their ability to switch between different {\em conformations}. In a conformation, the large scale geometric structure of the molecule is understood to be conserved, whereas on smaller scales the system may well rotate, oscillate or fluctuate. In a recent article [J. Comp. Phys., 151,1 (1999)], the present author and coworkers demonstrated that (a) conformations can be understood as almost invariant sets of some Markov chain being defined via the Hamiltonian system governing the molecular dynamics and that (b) these sets can efficiently be computed via eigenvectors of the corresponding Markov operator. The persent manuscript reviews the mathematical modelling steps behind the novel concept, includes a rigorous analytical justification of this approach and especially of the numerical details of the algorithm, and illustrates its performance when applied to realistic molecular systems.
    Keywords: ddc:000
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 33
    facet.materialart.
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    Publication Date: 2020-11-13
    Description: Der neue ''verteilte'' Bibliotheksverbund KOBV erfordert neue Arbeitsweisen und neue Formen der Zusammenarbeit der Bibliotheken untereinander. Im KOBV wird es keine zentrale Erschließung geben, sondern die Erschließung wird lokal, in den Bibliotheken durchgeführt. Entsprechend ihren Nutzerbedürfnissen bestimmen die Bibliotheken die Erschließungsart, den Erschließungsumfang und die Erschließungstiefe selbst. Als gemeinsamer regionaler Standard wird lediglich ein ''Mindeststandard'' auf der Basis von RAK-WB definiert. Dieser Gemeinsame KOBV-Standard berücksichtigt vor allem suchrelevante Elemente, um den Nutzern im KOBV möglichst einheitliche Sucheinstiege zu bieten. Der Gemeinsame KOBV-Standard wird in diesem Papier vorgestellt.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 34
    Publication Date: 2020-11-13
    Description: Die KOBV-Suchmaschine verarbeitet Daten im bibliographischen Datenformat MAB2 (Maschinelles Austauschformat für Bibliotheken, Ausgabe 2), das in deutschsprachigen Ländern angewandt wird. Im MAB2-Format sind für mehrbändige begrenzte Werke und fortlaufende Sammelwerke hierarchische Strukturen realisiert - mit bis zu drei Hierarchiestufen und unterschiedlichem Aufbau, je nachdem, ob es sich um ein begrenztes Werk oder um ein Werk ohne geplanten Abschluß handelt. Jede hierarchische Stufe entspricht einem Datensatz, die zusammengehörigen Datensätze sind miteinander verknüpft. Inhaltlich enthält eine Stufe oft nur Teilinformationen des Werkes; erst die Stufen zusammen ergeben die vollständige Information. In der KOBV-Suchmaschine werden Dokumente aus verschiedenen Bibliotheken zusammengeführt. Hierarchische Strukturen potenzieren gewissermaßen die mit der Dublettenbehandlung (Match- und Merge-Verfahren) verbundene Problematik: Es müssen nicht nur Datensätze aus verschiedenen Bibliotheken zusammengeführt werden, sondern darüber hinaus die zusammengehörigen Datensätze der unterschiedlichen Hierarchiestufen. Der Artikel enthält eine ausführliche Analyse der in MAB2 vorkommenden hierarchischen Strukturen, beschreibt die Anforderungen für die Lieferung hierarchischer Datensätze aus den lokalen Systemen und stellt das Verfahren vor, wie in der KOBV-Suchmaschine mit diesen hierarchischen Datenstrukturen bei der Dublettenbehandlung umgegangen wird. Anhand von Fallbeispielen wird die Problematik der Verknüpfung zusammengeführter h-Sätze erörtert. Die KOBV-Suchmaschine verarbeitet Daten im bibliographischen Datenformat MAB2 (Maschinelles Austauschformat für Bibliotheken, Ausgabe 2), das in deutschsprachigen Ländern angewandt wird. Im MAB2-Format sind für mehrbändige begrenzte Werke und fortlaufende Sammelwerke hierarchische Strukturen realisiert - mit bis zu drei Hierarchiestufen und unterschiedlichem Aufbau, je nachdem, ob es sich um ein begrenztes Werk oder um ein Werk ohne geplanten Abschluß handelt. Jede hierarchische Stufe entspricht einem Datensatz, die zusammengehörigen Datensätze sind miteinander verknüpft. Inhaltlich enthält eine Stufe oft nur Teilinformationen des Werkes; erst die Stufen zusammen ergeben die vollständige Information. In der KOBV-Suchmaschine werden Dokumente aus verschiedenen Bibliotheken zusammengeführt. Hierarchische Strukturen potenzieren gewissermaßen die mit der Dublettenbehandlung (Match- und Merge-Verfahren) verbundene Problematik: Es müssen nicht nur Datensätze aus verschiedenen Bibliotheken zusammengeführt werden, sondern darüber hinaus die zusammengehörigen Datensätze der unterschiedlichen Hierarchiestufen. Der Artikel enthält eine ausführliche Analyse der in MAB2 vorkommenden hierarchischen Strukturen, beschreibt die Anforderungen für die Lieferung hierarchischer Datensätze aus den lokalen Systemen und stellt das Verfahren vor, wie in der KOBV-Suchmaschine mit diesen hierarchischen Datenstrukturen bei der Dublettenbehandlung umgegangen wird. Anhand von Fallbeispielen wird die Problematik der Verknüpfung zusammengeführter h-Sätze erörtert.
    Keywords: ddc:000
    Language: German
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  • 35
    Publication Date: 2014-02-26
    Description: This paper summarizes and discusses various characterizations of perfect graphs and mentions some open problems in this area.
    Keywords: ddc:000
    Language: English
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  • 36
    Publication Date: 2020-11-13
    Description: Die Recherche über die KOBV-Suchmaschine liefert Datensätze aus unterschiedlichen Bibliotheken. Damit der Nutzer nicht viele, unter Umständen lange Listen für jede Bibliothek durchblättern muss werden die Datensätze in der KOBV-Suchmaschine einer Dublettenbehandlung (Match- und Merge-Verfahren) unterzogen. Ziel dieses Verfahrens ist es, dem Nutzer möglichst nur einen einzigen Datensatz mit allen zugehörigen Bestandsnachweisen aus den Bibliotheken anzuzeigen. In dem vorliegenden Papier steht das Match-Verfahren, das von der KOBV-Projektgruppe eigens für den Einsatz in der KOBV-Suchmaschine entwickelt wurde, im Vordergrund. Das Merge-Verfahren, das auf Konzepte von Ex Libris zurückgeht, ist lediglich am Rande erwähnt. Ziel bei der Entwicklung des Match- und Merge-Verfahrens war es, in der KOBV-Suchmaschine ein Verfahren zu implementieren, das vollkommen automatisiert, ohne Zuhilfenahme manueller und intellektueller Eingriffe, abläuft. In diesem Papier sind die Grundlagen zum Match- und Merge-Verfahren in der KOBV-Suchmaschine zusammengefaßt. Zunächst wird definiert, was unter einer Dublette überhaupt zu verstehen ist. Die Begriffe Dokument und Werk werden analysiert, die wesentlich sind für die Entscheidung, welche Datensätze in der KOBV-Suchmaschine letztendlich zusammengeführt werden. Anhand umfassender Literaturrecherchen werden die zur Dublettenbehandlung herangezogenen bibliographischen Beschreibungselemente (Attribute) in verschiedenen MARC- und MAB-Datenbanken ermittelt und grundsätzliche Probleme beim Erkennen dubletter bibliographischer Datensätze aufgezeigt. Schließlich werden Verfahren vorgestellt und diskutiert, wie die Attribute in das Match- und Merge-Verfahren eingebunden werden: bei nur einer Gewichtung (positiver Wert) und bei zwei Gewichtungen (positiver und negativer Wert). Auf dieser Basis werden Tabellen mit Werten für zwei unterschiedliche Gewichtungsverfahren in der KOBV-Suchmaschine entwickelt, die als Ausgangswerte für erste Testverfahren in den Match- und Merge-Algorithmus in der KOBV-Suchmaschine implementiert werden.
    Keywords: ddc:000
    Language: German
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  • 37
    Publication Date: 2020-03-23
    Description: Abstract-Sammlung zum gleichnamigen Workshop am ZIB vom 19.--20. Mai 1999
    Keywords: ddc:000
    Language: German
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  • 38
    Publication Date: 2014-02-27
    Description: This monograph has been written to illustrate the interlocking of theory, algorithm, and application in developing solution techniques for complex PDE systems. A deep theoretical understanding is necessary to produce a powerful idea leading to a successful algorithm. Efficient and robust implementation is the key to make the algorithm perform satisfactorily. The extra insight obtained by solving real--life problems brings out the structure of the method more clearly and suggests often ways to improve the numerical algorithm. It is my intention to impart the beauty and complexity found in both the theoretical investigation of the adaptive algorithm proposed here, i.e., the coupling of Rosenbrock methods in time and multilevel finite elements in space, and its realization. I hope that this method will find many more interesting applications.
    Keywords: ddc:000
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 39
    Publication Date: 2014-02-26
    Description: Many optimization problems have several equivalent mathematical models. It is often not apparent which of these models is most suitable for practical computation, in particular, when a certain application with a specific range of instance sizes is in focus. Our paper addresses the Asymmetric Travelling Salesman Problem with time windows (ATSP-TW) from such a point of view. The real--world application we aim at is the control of a stacker crane in a warehouse. We have implemented codes based on three alternative integer programming formulations of the ATSP-TW and more than ten heuristics. Computational results for real-world instances with up to 233 nodes are reported, showing that a new model presented in a companion paper outperforms the other two models we considered --- at least for our special application --- and that the heuristics provide acceptable solutions.
    Keywords: ddc:000
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  • 40
    Publication Date: 2014-02-26
    Description: Das Konrad-Zuse-Zentrum für Informationstechnik Berlin (ZIB) und das Rechenzentrum der Universität Rostock, beide Einrichtungen betreiben massiv-parallele Rechner vom Typ CRAY T3E, haben sich an Hand einer Anwendung aus dem Bereich der Botanik mit den Möglichkeiten der Verteilung auf zwei Parallelrechner, gekoppelt nur über das Breitband-Wissenschaftsnetz des Deutschen Forschungsnetzes, vertraut gemacht. Das Projekt besteht aus zwei Teilen. Im ersten Teil wird ausführlich das zwischen den Rechnern liegende Netz und die Ergebnisse einer Performanceanalyse dieses Netzes dokumentiert. Der zweite Teil beschreibt die Anwendung "Simulation des Wachstums von Pflanzen"' sowie die Ergebnisse der Verteilung dieser Anwendung auf beide Rechner. \begin{center} \bf{Abstract} \end{center} The "'Konrad-Zuse-Zentrum für Informationstechnik Berlin"' (ZIB) and the Computing Centre of the University of Rostock operate high-performance computers of type CRAY T3E. In this project an application from the area of the botany is distributed on two parallel computers, only coupled through the Broadband Science Network of the German Research Network (DFN). This project consists of two parts. In the first part the network which is situated between the computers and the results of a performance analysis is documented in detail. The second part describes the application "'Simulation of the growth of plants"' as well as the results of the distribution of this application to both computers.
    Keywords: ddc:000
    Language: German
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  • 41
    Publication Date: 2014-02-26
    Description: The method of symmetry adapted wavepackets (SAWP) to solve the time-dependent Schrödinger equation for a highly symmetric potential energy surface is introduced. The angular dependence of a quantum-mechanical wavepackets is expanded in spherical harmonics where the number of close-coupled equations for the corresponding radial functions can be efficiently reduced by symmetry adaption of the rotational basis using the SWAP approach. Various techniques to generate symmetry adapted spherical harmonics (SASHs) for the point groups of highest symmetry (octahedral, icosahedral) are discussed. The standard projection operator technique involves the use of Wigner rotation matrices. Two methods to circumvent numerical instabilities occuring for large azimuthal quantum numbers are suggested. The first is based on a numerical scheme which employs Gaussian integrations yielding exact and stable results. The second is a recursive algorithm to generate higher order SASHs accurately and efficiently from lower order ones. The paper gives a complete set of ``seed functions'' generated by projection techniques which can be used obtain SASHs for all irreducible representations of the octahedral and icosahedral point groups recursively.
    Keywords: ddc:000
    Language: English
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  • 42
    Publication Date: 2014-02-26
    Description: The article surveys the development of novel mathematical concepts and algorithmic approaches based thereon in view of their possible applicability to biomolecular design. Both a first deterministic approach, based on the Frobenius-Perron operator corresponding to the flow of the Hamiltonian dynamics, and later stochastic approaches, based on a spatial Markov operator or on Langevin dynamics, can be subsumed under the unified mathematical roof of the transfer operator approach to effective dynamics of molecular systems. The key idea of constructing specific transfer operators especially taylored for the purpose of conformational dynamics appears as the red line throughout the paper. Different steps of the algorithm are exemplified by a trinucleotide molecular system as a small representative of possible RNA drug molecules.
    Keywords: ddc:000
    Language: English
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  • 43
    Publication Date: 2020-03-09
    Description: In this paper we discuss several ways to visualize stationary and non-stationary quantum mechanical systems. We demonstrate an approach for the quantitative interpretation of probability density isovalues which yields a reasonable correlation between isosurfaces for different timesteps. As an intuitive quantity for visualizing the momentum of a quantum system we propose the probability flow density which can be treated by vector field visualization techniques. Finally, we discuss the visualization of non-stationary systems by a sequence of single timestep images.
    Keywords: ddc:000
    Language: English
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  • 44
    Publication Date: 2014-02-26
    Description: One of the important tasks in Data Mining is automated cluster analysis. Self-Organizing Maps (SOMs) introduced by {\sc Kohonen} are, in principle, a powerful tool for this task. Up to now, however, its cluster identification part is still open to personal bias. The present paper suggests a new approach towards automated cluster identification based on a combination of SOMs with an eigenmode analysis that has recently been developed by {\sc Deuflhard et al.} in the context of molecular conformational dynamics. Details of the algorithm are worked out. Numerical examples from Data Mining and Molecular Dynamics are included.
    Keywords: ddc:000
    Language: English
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  • 45
    Publication Date: 2014-02-26
    Description: The photoassociation process shows strong dependence on the temporal duration of the electromagnetic field pulses and their frequencies. This dependence is investigated using quantum mechanical simulations that include all ranges of impact parameters and contributions from bound-to-bound transitions. The photoassociation yield of mercury atoms to produce excimer dimers is enhanced for short (ps) and for ultrashort (fs) pulse durations. Ultrashort laser pulses effectively overlap the entire range of free-to-bound transition, therefore achieving a maximum probability. Short pulses show a maximum in the photoassociation yield when their carrier frequency overlaps a particular free-to-bound spectroscopic resonance. Implications of these calculations on efforts to control bimolecular reactions are discussed.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 46
    Publication Date: 2014-02-26
    Description: For using Data Mining, especially cluster analysis, one needs measures to determine the similarity or distance between data objects. In many application fields the data objects can have different information levels. In this case the widely used euclidean distance is an inappropriate measure. The present paper describes a concept how to use data of different information levels in cluster analysis and suggests an appropriate similarity measure. An example from practice is included, that shows the usefulness of the concept and the measure in combination with {\sc Kohonens} Self-Organizing Map algorithm, a well-known and powerful tool for cluster analysis.
    Keywords: ddc:000
    Language: English
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  • 47
    Publication Date: 2020-11-13
    Description: Auf dem 89. Deutschen Bibliothekartag, der vom 25. bis 29. Mai 1999 in Freiburg (Breisgau) stattgefunden hat, wurde der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) zum ersten Mal der großen bibliothekarischen Öffentlichkeit vorgestellt. Am KOBV-Stand, der im Rahmen des gemeinsamen Standes der Arbeitsgemeinschaft der Verbundsysteme organisiert wurde, führte die KOBV-Projektgruppe Funktionalitäten der KOBV-Suchmaschine vor. In der Vortragsreihe zum Themenkreis XI "Neue Entwicklungen in den Verbund- und Lokalsystemen", die unter Mitwirkung der Arbeitsgemeinschaft der Verbundsysteme veranstaltet wurde, war der KOBV mit einem eigenen Vortrag vertreten: "Der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) - Ein innovatives Verbundkonzept für die Region". In dem Vortrag hat die Verfasserin einen umfassenden Überblick über das KOBV-Projekt und den bisherigen Projektverlauf gegeben, die Projektziele und den politischen Rahmen erörtert sowie die KOBV-Suchmaschine, das technische Kernstück des neuen Verbundes, vorgestellt. Der hier vorliegende Text ist die schriftlich ausgearbeitete Fassung dieses Vortrages.
    Keywords: ddc:000
    Language: German
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  • 48
    Publication Date: 2021-03-16
    Description: This survey presents cutting planes that are useful or potentially useful in solving mixed integer programs. Valid inequalities for i) general integer programs, ii) problems with local structure such as knapsack constraints, and iii) problems with 0-1 coefficient matrices, such as set packing, are examined in turn. Finally the use of valid inequalities for classes of problems with structure, such as network design, is explored.
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  • 49
    Publication Date: 2014-02-26
    Description: The improvement of simulations of QCD with dynamical Wilson fermions by combining the Hybrid Monte Carlo algorithm with parallel tempering is studied. As an indicator for decorrelation the topological charge is used.
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    Language: English
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  • 50
    Publication Date: 2020-11-13
    Description: Im Herbst 1999 nimmt die KOBV-Suchmaschine, das technische "Herzstück" des KOBV, den Routinebetrieb auf. Nach einer kurzen Einführung in die politischen und rechtlichen Grundlagen des KOBV-Projektes werden in diesem Aufsatz die Funktionalitäten der KOBV-Suchmaschine, ihre Leistungen für Bibliotheksbenutzer und Bibliothekare, vorgestellt. Der Aufsatz schließt mit einem Überblick über den bisherigen Projektverlauf und der Erläuterung der wichtigsten Prinzipien des KOBV - Offenheit, Dezentralität und Heterogenität.
    Keywords: ddc:000
    Language: German
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  • 51
    Publication Date: 2014-02-26
    Description: This series of lectures has been given to a class of mathematics postdocs at a European summer school on Computational Mathematics Driven by Industrial Applications in Martina Franca, Italy (organized by CIME). It deals with a variety of challenging real life problems selected from clinical cancer therapy, communication technology, polymer production, and pharmaceutical drug design. All of these problems from rather diverse application areas share two common features: (a) they have been modelled by various differential equations -- elliptic, parabolic, or Schrödinger--type partial differential equations, countable ordinary diffential equations, or Hamiltonian systems, (b) their numerical solution has turned out to be real challenge to computational mathematics.
    Keywords: ddc:000
    Language: English
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  • 52
    Publication Date: 2014-02-26
    Description: Semidefinite relaxations of quadratic 0-1 programming or graph partitioning problems are well known to be of high quality. However, solving them by primal-dual interior point methods can take much time even for problems of moderate size. The recent spectral bundle method of Helmberg and Rendl can solve quite efficiently large structured equality-constrained semidefinite programs if the trace of the primal matrix variable is fixed, as happens in many applications. We extend the method so that it can handle inequality constraints without seriously increasing computation time. Encouraging preliminary computational results are reported.
    Keywords: ddc:000
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  • 53
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    Publication Date: 2019-01-29
    Description: The C++ standard template library has many useful containers for data. The standard library includes two adpators, queue, and stack. The authors have extended this model along the lines of relational database semantics. Sometimes the analogy is striking, and we will point it out occasionally. An adaptor allows the standard algorithms to be used on a subset or modification of the data without having to copy the data elements into a new container. The authors provide many useful adaptors which can be used together to produce interesting views of data in a container.
    Keywords: ddc:000
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  • 54
    Publication Date: 2014-02-26
    Description: This report describes the development of an experimental service for picture-based document retrieval for the Electronic Visualization Library (EVlib). The EVlib is a digital library for scientific visualization, established at the Konrad-Zuse-Zentrum für Informationstechnik Berlin (ZIB). The picture-based retrieval service allows users to look for documents by describing the pictures they contain. This query method was developed based on the assumption that (1) pictures often represent relevant parts of the contents of a document, and (2) pictures are often remembered well. A picture-based approach provides a new quality of accessing and exploring scientific literature. Motivation, concepts and realization of our service are outlined. Results of a user test are presented, too. The results indicate that this service can be used for searching and browsing the document collection in principle. On the other hand, problems were detected which can give fruitful hints for future work concerning document and image retrieval.
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  • 55
    facet.materialart.
    Unknown
    Publication Date: 2019-10-24
    Keywords: ddc:000
    Language: German
    Type: annualzib , doc-type:report
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  • 56
    Publication Date: 2022-07-07
    Description: In this paper, we generalize the nonlocal discrete transparent boundary condition introduced by Schmidt and Deuflhard {[}Comp. Math. Appl. 29 (1995) 53-76{]} and Schmidt and Yevick {[}J. Comput. Phys. 134 (1997) 96-107{]} to propagation methods based on arbitrary Pad\'e approximations to the two-dimensional one-way Helmholtz equation. Our approach leads to a recursive formula for the coefficients appearing in the nonlocal condition which then yields an unconditionally stable propagation method.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 57
    Publication Date: 2022-07-07
    Description: We present nonlocal discrete transparent boundary conditions for a fourth-order wide-angle approximation of the two-dimensional Helmholtz equation. The boundary conditions are exact in the sense that they supply the same discrete solution on a bounded interior domain as would be obtained by considering the problem on the entire unbounded domain with zero boundary conditions at infinity. The proposed algorithm results in an unconditionally stable propagation method. Numerical examples from optics illustrate the efficiency of our approach.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
    Format: application/postscript
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  • 58
    ISSN: 1530-0358
    Keywords: Endoanal ; Magnetic resonance imaging ; Vector volume ; Manometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PURPOSE: This study compared conventional water-perfused and vector volume anal manometry in female patients with neurogenic fecal incontinence and chronic anal fissure and in healthy female volunteers. We used endoanal magnetic resonance (MR) imaging to measure internal and external sphincter lengths and thicknesses and contrasted these with the manometric findings in the different anorectal conditions. METHODS: One hundred thirty-three female subjects were studied over an eight-month period, including 33 control volunteers, 83 patients with neurogenic fecal incontinence, and 17 patients with chronic anal fissure. Conventional manometry was contrasted with automated vector volume-derived parameters. Endoanal magnetic resonance images were obtained using a previously described internal coil with a 0.5 T Asset™ scanner measuring quadrantal internal sphincter thickness and averaged coronal internal and external sphincter lengths. RESULTS: There was a statistically significant relationship between parameters measured by conventional manometry and those variables derived from vector volume manometry at rest and squeeze. There was no difference in sectorial vector-derived pressures within any anorectal condition and no correlation between quadrantal internal sphincter thickness measurements and sectorial pressures at rest. Patients with chronic anal fissure and neurogenic fecal incontinence had constitutionally shorter superficial and subcutaneous external sphincters than healthy control subjects (P〈0.001). CONCLUSIONS: There is no association between manometric findings and morphologic sphincter measurement; however, the shorter distal external sphincter in patients with fissure might render the lower anal canal relatively unsupported after internal sphincterotomy in the female patient.
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  • 59
    ISSN: 1530-0358
    Keywords: Rectal cancer ; Transrectal ultrasonography ; Computerized tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PURPOSE: The preoperative assessment of rectal cancer wall invasion and regional lymph node metastasis is essential for the planning of optimal therapy. This study was done to determine the accuracy and clinical usefulness of transrectal ultrasonography, pelvic computed tomography, and magnetic resonance imaging in preoperative staging. METHODS: A total of 89 patients with rectal cancer were examined with transrectal ultrasonography (n=89), pelvic computed tomography (n=69), and magnetic resonance imaging with endorectal coil (n=73). The results obtained by these diagnostic modalities were compared with the histopathologic staging of specimens. RESULTS: In staging depth of invasion, the overall accuracy was 81.1 percent (72/89) by transrectal ultrasonography, 65.2 percent (45/69) by computed tomography, and 81 percent (59/73) by magnetic resonance imaging. Overstaging was 10 percent (9/89) by transrectal ultrasonography, 17.4 percent (12/69) by computed tomography, and 11 percent (8/73) by magnetic resonance imaging; and understaging was 8 of 89 (8.9 percent) by transrectal ultrasonography, 12 of 69 (17.4 percent) by computed tomography, and 6 of 73 (8 percent) by magnetic resonance imaging. In staging lymph node metastasis, the overall accuracy rate was 54 of 85 (63.5 percent) in transrectal ultrasonography, 39 of 69 (56.5 percent) in computed tomography, and 46 of 73 (63 percent) in magnetic resonance imaging. The sensitivity was 24 of 45 (53.3 percent) in transrectal ultrasonography, 14 of 25 (56 percent) in computed tomography, and 33 of 42 (78.5 percent) in magnetic resonance imaging; and specificity was 30 of 40 (75.0 percent) in transrectal ultrasonography, 25 of 44 (56.8 percent) in computed tomography, and 13 of 31 (41.9 percent) in magnetic resonance imaging. The accuracy in detection of positive lateral pelvic lymph nodes under magnetic resonance imaging (n=8) was 12.5 percent. The accuracy in detection of posterior vaginal wall invasion was 100 percent in transrectal ultrasonography (n=7) and 100 percent in magnetic resonance imaging (n=3), but 28.5 percent in computed tomography (n=7). CONCLUSIONS: Both transrectal ultrasonography and magnetic resonance imaging with endorectal coil exhibited similar accuracy and were superior to conventional computed tomography in preoperative assessment of depth of invasion and adjacent organ invasion. Because transrectal ultrasonography is a safer and more cost-effective modality than magnetic resonance imaging, transrectal ultrasonography is an appropriate method for preoperative staging of rectal cancer. Further efforts will be needed to provide a better staging of lymph node involvement.
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  • 60
    ISSN: 1436-2813
    Keywords: Key Words: chemoendocrine therapy ; pure antiestrogen ; 5-fluorouracil ; nude mouse ; breast cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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  • 61
    Electronic Resource
    Electronic Resource
    Springer
    Trauma und Berufskrankheit 1 (1999), S. S92 
    ISSN: 1436-6274
    Keywords: Schlüsselwörter Wachstumsalter ; MRI ; Beckenfraktur ; Wirbelsäulenfraktur ; Key words Childhood ; Magnetic resonance imaging ; Pelvic fracture ; Spinal injury
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract According to the literature, from 1950 to 1995 the overall risk for children of sustaining a fracture of the spinal column or the pelvic ring doubled, the main reason being the increasing incidence of high-energy trauma caused by newly popular sporting activities such as skateboarding, inline skating and mountain biking. Nonetheless, even specialized pediatric level I trauma centers in Europe and the United States of America report an incidence of below 5% for severe spinal injuries and fractures of the pelvis. Although these specific injury patters are seen relatively infrequently, whenever present they are still highly indicative of high-velocity injury mechanisms, frequently revealing a combination of injuries – each of which would be serious in itself – involving the body cavities and the soft tissues of the trunk an extremities. In summary, spinal cord injuries and pelvic ring fractures are rare but can be serious: cervical and spinal cord injuries without radiological abnormality appear to be more frequent than in adults, and the availability of nuclear magnetic imaging technologies has helped in the diagnosis of unsuspected cord injury in children. In addition, retrospective analysis of purely nonoperative management of highly unstable C-type injuries of the spine and the pelvic ring reveal some unsatisfactory results, so that specifically for these injury morphologies the alternative of an operative strategy might be considered. The purpose of this presentation is to discuss various injury patterns in which an operative concept could be considered, particularly for a multiply injured child.
    Notes: Zusammenfassung Verletzungen des Rückenmarks und Sprengungen des knöchernen Beckenrings liegen im Kindesalter auch im Krankengut spezialisierter Zentren unter 5%. Besonders beachtenswert erscheint hierbei, daß Rückenmark- und besonders Halswirbelsäulenverletzungen v. a. beim Kind häufig keine ossäre Mitbeteiligung der Wirbelsäule zeigen und erst durch kernspintomographische Diagnostik erfaßt werden können. Desgleichen zeigt sich bei der retrospektiven Auswertung, daß ein pauschales, rein konservatives Management aller Verletzungstypen, d. h. v.a. der sog. C-Verletzungstypen an der Wirbelsäule und am Becken, z. T. unbefriedigende Behandlungsergebnisse zeigt und daher zunehmend bei bestimmten, im weiteren näher besprochenen Verletzungskonstellationen ein eher operatives Grundkonzept diskutiert wird. Neue Erkenntnisse zur Diagnostik und Therapie der Wirbelsäulen- und Beckenverletzung beim Kind liegen insofern vor, als 1. neuere epidemiologische Erhebungen heute eine präzisere, d. h. nicht nur empirisch gesicherte Unterscheidung der selten von eher regelmäßig anzutreffenden Verletzungstypen und Frakturmorphologien erlauben, 2. durch vergleichsweise „neue“ Sportarten wie „Scate-boarding“ und „Mountain-biking“ ganz generell eine statistisch belegte Zunahme von Hochrasanztraumen und komplexen Verletzungsmustern beim Kind beobachtet werden kann sowie 3. generell v.a. beim mehrfachverletzten Kind heute eine eher aggressivere Gangart, d. h. ein in bestimmten Einzelaspekten eher operatives Versorgungskonzept angestrebt wird. Gegenstand der vorliegenden Arbeit sind 1. eine Analyse der als besonders bedeutsam erkannten Verletzungsformen sowie 2. eine Darstellung der heute in Veränderung begriffenen Behandlungskonzepte v.a. beim mehrfachverletzten Kind.
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  • 62
    ISSN: 1436-2813
    Keywords: chemoendocrine therapy ; pure antiestrogen ; 5-fluorouracil ; nude mouse ; breast cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The antitumor effects of an experimental chemoendocrine therapy combining a new pure antiestrogen ICI 182780 and 5-fluorouracil (5-FU) were studied on MCF-7 human breast cancer cells implanted in nude mice. ICI 182780 had a dose-dependent antitumor activity, which was potentiated by the concomitant use of 5-FU. When compared with the control group, the estrogen receptor (ER) level in the ICI 182780 group was lower and that in the combination group was markedly lower. Cell cycle analysis by flow cytometry (FCM) resulted in a lower percentage of S-phase cells (%S) in the treated mice. No significant difference was observed in the 5-FU concentrations in tumor cells, while the 5-FU content in RNA was significantly higher in the combination group. The changes in free thymidylate synthetase (TS) concentration indicated TS synthesis after the administration of 5-FU to be more greatly suppressed in the combination group than in the 5-FU group. These results suggest that ICI 182780 and 5-FU exert their combination effect mainly on ER-positive cells, and that the suppression of TS synthesis in tumor cells and the potentiation of the 5-FU-induced metabolic dysfunction of RNA are thus involved in the mode of action of this combination therapy.
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  • 63
    ISSN: 1569-8041
    Keywords: breast cancer ; old age ; vinorelbine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Older patients with advanced breast cancer are less likely to receive chemotherapy than younger patients. Vinorelbine is an attractive alternative in this setting because of its clinical activity and low frequency of side effects. This multicenter, phase II trial was designed to assess the safety and efficacy of intravenous vinorelbine as first-line therapy in women ≥60 years old. Patients and methods: Fifty-six women (median age, 72 years; range 60–84 years), with measurable advanced breast cancer and no prior chemotherapy for metastatic disease, were enrolled and included in the analysis. Vinorelbine 30 mg/m2 was administered weekly for 13 weeks and then every two weeks until development of progressive disease; doses were reduced or delayed to manage toxicity. Results: The objective response rate was 38% (95% confidence interval (95% CI): 24%–51%); median duration of response, nine months; median time to disease progression in all patients, six months. The major dose-limiting toxicity was hematologic, which led to a median dose intensity of 20.6 mg/m2/week. Grade 3–4 nonhematologic toxicity consisted of asthenia (7%); nausea and generalized pain (5%); vomiting, chest pain, abdominal pain, and elevated AST (4%); fever, diarrhea, constipation, and injection site reaction (2%). Neurotoxicity and alopecia were grade 1–2 and relatively infrequent. Conclusions: Vinorelbine offers a promising alternative for the management of advanced breast cancer in elderly patients who are concerned about the subjective side effects of cytotoxic chemotherapy. The dose-limiting toxicity is neutropenia, which is readily managed with dose adjustment. Nonhematologic toxicity, including gastrointestinal side effects, is minimal. Randomized studies are warranted to compare the activity of vinorelbine with that of other regimens in elderly patients.
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  • 64
    Electronic Resource
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    Italian journal of neurological sciences 20 (1999), S. 55-58 
    ISSN: 1126-5442
    Keywords: Key words Rhombencephalopathy ; Radionecrosis ; Magnetic resonance imaging ; Hyperbaric oxygen ; Heparin ; Buspirone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report the case of a patient who underwent radiotherapy of the neck because of an epidermoid carcinoma in Rosenmüller's fossa. Eleven months later, T1-weighted brain magnetic resonance imaging (MRI) revealed a bulbo-pontine lesion, and the clinical course and sequential MRI results led to a diagnosis of radionecrosis-induced rhombencephalopathy. At a distance of more than three years, the lesion is no longer visible on MRI images but the severe neurological deficits remain. The clinical picture has not been improved by treatment with prednisone, hyperbaric oxygen, symptomatic therapies or anticoagulants.
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  • 65
    ISSN: 1126-5442
    Keywords: Key words Hepatolenticular degeneration ; Affective disorders ; Magnetic resonance imaging ; Antidepressive agents ; Interpersonal psychotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We describe a case of Wilson's disease with late psychiatric onset. Major depressive disorder was the first clinical manifestation at the age of 38 years. After pharmacotherapy with antidepressive agents, a manic episode was oberseved. Extrapyramidal hand tremor and micrography were the first neurological signs. Emotional lability occurred during worsening of extrapyramidal signs. Diagnosis was based on urinary and serum copper levels, ceruloplasmin serum level, Kayser-Fleischer ring, and liver biopsy that detected cirrhosis. Magnetic resonance imaging revealed basal ganglia hyperintensity on T1-weighted images, and hypodensity in the central part and hyperintensity in the peripheral part of the lentiform nucleus on 72-weighted images. Hyperintensity on T2-weighted images was also observed in the dorsal part of the midbrain. 123I-iodobenzamide single photon emission computed tomography (IBZM-SPECT) detected a normal distribution of the drug in the brain, with better signal in the right side and deficit of D2-dopaminergic receptors in the basal ganglia, Abnormal manganese erythrocyte level was observed. Treatment was based on penicillamine, zinc salts, low-copper diet, antidepressant agents, interpersonal psychotherapy and neurorehabilitation.
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  • 66
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    Emergency radiology 6 (1999), S. 282-289 
    ISSN: 1438-1435
    Keywords: Key words Radiology ; Computed tomography ; Magnetic resonance imaging ; Soft-tissue sign ; Arm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract More modern imaging techniques allow us to supplement the information available on soft-tissue signs seen on radiographs. This improves our diagnostic capability, as demonstrated here in the upper extremity.
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  • 67
    ISSN: 1438-1435
    Keywords: Key words Spinal cord ; Birth injury ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We present the acute MR findings in an infant with a complicated traumatic delivery, asphyxia, spinal cord injury, and a radiographically apparent cervical spine fracture-dislocation. MRI including diffusion-weighted imaging allowed early characterization and localization of the extent of spinal cord injury.
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  • 68
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    Springer
    Neurosurgical review 22 (1999), S. 112-116 
    ISSN: 1437-2320
    Keywords: Key words Ganglioma ; Brain tumor ; Magnetic resonance imaging ; Epilepsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The authors present the case of a 33-year-old patient with a bifocal ganglioglioma located in the right superior temporal gyrus. He had a history of tonic–clonic seizures and developed intermittent nausea and vertigo later on. Magnetic resonance imaging showed two distinct, small lesions in the right temporal lobe. Both tumors were removed microsurgically with ultrasound guidance. Intraoperatively, two distinct tumors were found. Histological diagnosis of both tumors was of ganglioglioma WHO II. Postoperatively, the patient was free of symptoms. Bifocal occurrence or the coincidence of two distinct gangliogliomas is a very uncommon finding. So far, it has not yet been reported in benign gangliogliomas.
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  • 69
    ISSN: 1437-2320
    Keywords: Key words Cerebellopontine angle ; Constructive interference in steady-state imaging ; Diffusion-weighted imaging ; Epidermoid tumor ; Magnetic resonance imaging ; Surgical treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We describe the usefulness of three-dimen-sional Fourier transformation-constructive interference in steady-state (CISS) imaging and diffusion-weighted imaging (DWI) in the pre- and postoperative magnetic resonance imaging evaluation of intracranial epidermoid tumors. Two surgically proven epidermoid tumors in the cerebellopontine (CP) angle were not identified in conventional T1- and T2-weighted images because of a signal intensity similar to that of cerebrospinal fluid (CSF). CISS images clearly demonstrated displacement of the cranial nerves and a shift caused by a lesion in the cistern, but the signal intensity of the tumor by CISS was not sufficiently different from that of CSF to demonstrate the tumor directly. Using DWI, the tumor in the cistern was shown clearly by its increased signal intensity. Together, CISS and DWI compensated for each other's disadvantages, and this combination was useful in guiding surgical treatment of epidermoid tumors in the CP cistern.
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  • 70
    ISSN: 1437-2320
    Keywords: Key words Brain tumor ; Cerebral hydatidosis ; Chitinoma ; Echinococcosis ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Solitary brain affection is rare in echinococcosis. We report the case of a 35-year-old woman presenting with symptomatic grand-mal epilepsy due to a right frontal, partially cystic space-occupying lesion. Pre-operative computed tomography and magnetic resonance imaging (MRI) suggested a cystic astrocytoma. However, histological examination yielded the diagnosis of a `chitinoma', a rare subtype of solid cerebral hydatid disease (echinococcosis). It mimicked a primary brain tumor and, therefore, posed a diagnostic problem. We present the – to our knowledge – first MRI scans in a case of a histologically proven chitinoma.
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  • 71
    ISSN: 1569-8041
    Keywords: breast cancer ; fibroblast growth factor ; microvasculature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Angiogenesis, the process whereby endothelial cells divide and migrate to form new blood capillaries, has been assessed in tumours by measuring microvessel density. High microvessel density is a significant adverse prognostic factor in breast cancer. The angiogenic factor, basic fibroblast growth factor (bFGF), has been associated with tumourigenesis and metastasis in several human cancers. There are few quantitative studies of bFGF expression in normal tissues compared to cancer. Patients and methods: We have measured bFGF levels in 149 human primary breast carcinomas and assessed the findings in relation to microvessel density, oestrogen receptor (ER) and epidermal growth factor receptor (EGFR). Basic FGF levels were measured by ELISA. Western blotting and immunohistochemistry were carreid out to confirm the presence of bFGF. Results: Levels of bFGF were more than 10-fold higher in tumour cytosols compared to reduction mammoplasty tissue and 3-fold compared to non neoplastic cytosols from the same breast as the tumour (P 〈 0.0001). Immunohistochemistry showed bFGF protein was localised exclusively in the stroma whereas no bFGF staining was observed in the epithelial cells. High bFGF levels were significantly related to high ER (P = 0.01). Similarly, high bFGF levels were significantly related to low grade (P = 0.046) and to small tumour size (P = 0.04). No significant relationship was observed between bFGF and microvessel count, EGFR or age. In univariate analysis and in a Cox proportional hazard model bFGF did not reach significance for overall or relapse free survival. Conclusions: Our results show that although bFGF is elevated in breast carcinomas compared to normal breast tissue it is not related to microvessel density and it is not an independent predictor of survival in breast cancer patients. Basic FGF may be one of multiple factors that synergise with other growth factors such as VEGF to enhance angiogenesis.
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  • 72
    ISSN: 1569-8041
    Keywords: breast cancer ; high-dose chemotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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  • 73
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    Annals of oncology 10 (1999), S. 1163-1170 
    ISSN: 1569-8041
    Keywords: BRCA1 ; BRCA2 ; breast cancer ; family history ; survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Family history is a well recognized risk factor for breast cancer, but its impact in terms of breast cancer survival is uncertain. The recent identification of breast cancer predisposing genes has provided new clinical insights in this field. Design: English literature identified through Medline between 1976 and February 1999 was reviewed including search terms: breast cancer, survival, prognosis, family history, genetics, BRCA1, BRCA2, and related articles. Results: Publications were divided into three categories.Family history-based studies: eighteen articles were reviewed. Four studies showed a statistically significant better survival in patients with a family history of breast cancer, and two studies demonstrated a significantly worse prognosis in this context. The remaining articles showed no significant difference. Linkage studies: Two studies based on linkage to BRCA1 found that overall survival was better in linked families. A third one concluded to a worse outcome in BRCA2-linked tumors. Mutation-based studies: 10 studies looking at the association between germ-line mutations in BRCA1/BRCA2 and clinical outcomes were reviewed. Eight articles reported no significant difference in outcome, whereas two studies showed a worse outcome in patients with mutations. Conclusions: Conflicting data exist as to whether the prognosis of familial or hereditary breast cancer differs from that of sporadic cases. Some of the discrepancies may be explained by methodological differences or biases. However, no studies showed a survival advantage for BRCA1mutation carriers. This seems to indicate that BRCA1-related breast cancer is not associated with a survival advantage, and that in fact, certain BRCA1 germline mutations confer a worse prognosis. However, to adequately answer this question, more efficient molecular tools to identify all the genetic changes responsible for breast cancer predisposition, and large cohort studies to evaluate their clinical consequences, are needed.
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  • 74
    ISSN: 1569-8041
    Keywords: breast cancer ; chemotherapy ; margins ; radiotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Inadequate surgical excision with residual involvement of resection margins by tumour after breast conservation results in increased local recurrence rates. To reduce this risk positive margins are, therefore, usually excised. Systemic treatment with tamoxifen or chemotherapy reduces local recurrence, along with radiotherapy. However, no studies to date have examined the correlation between chemoendocrine treatment, together with radiotherapy, and local relapse in patients with unexcised involved resection margins, having had breast conservation treatment. Patients and methods: The histopathology reports were reviewed of 184 patients who were treated from June 1991 to August 1995 within our randomised study of neoadjuvant versus adjuvant chemoendocrine therapy with mitozantrone and methotrexate (2M) ± mitomycin-C (3M) and tamoxifen, used concurrently with radiation following conservation surgical treatment. Histological resection margin was considered positive if ductal carcinoma in situ (DCIS) or invasive carcinoma was present microscopically less than 1mm from the excision margin. Results: Although 38% of patients had unexcised microscopically involved margins, local relapse rate as first site of relapse was only 1.9% after a median follow up of 57 months. There was no difference in distant relapse (P = 0.2) and survival (P = 0.5) between the positive and negative margins groups. Conclusions: The presence of positive unexcised margins does not have a significant effect on outcome in patients who are treated with chemoendocrine therapy together with radiotherapy. Further clinical trials are required.
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  • 75
    ISSN: 1569-8041
    Keywords: breast cancer ; docetaxel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Given as first- or second-line chemotherapy, docetaxel appears to have great potential in advanced breast cancer. Patients and methods: Three hundred and seventy-seven locally advanced or metastatic breast cancer patients received docetaxel (Taxotere®) as part of a named patient programme under the care of 108 oncologists from 61 cancer units across the UK. The recommended starting dose was 100 mg/m2, but patients at higher risk of toxicity started at 75 mg/m2. All patients received corticosteroid premedication. The modal number of prior chemotherapy regimens was 2 (range 1–7), 342 patients (91%) had at least one prior anthracycline-based regimen. Results: Response was graded according to the managing clinician's best judgement without formal criteria. The overall response rate (ORR) was 46% among the 331 evaluable patients, 46% among the 299 patients who were 'anthracycline resistant' and 35% among the 82 patients who were 'anthracycline refractory' (progressive disease being the best response obtained to the most recent anthracycline containing regimen). One hundred and ninety-three patients started at the full dose of 100 mg/m2 with an ORR of 55% and 129 started at 75 mg/m2 with an ORR of 33%. In October 1997, some two years after the programme had started, 26 of 377 patients were still alive, although no complete remissions have lasted to this date. Kaplan–Meier survival analysis yielded a median survival of 194 days (95% CI: 178–218 days). Haematological parameters were checked before each course of docetaxel and additionally as clinically indicated. The safety data confirmed that docetaxel has a manageable, predictable side effect profile; 29 of 377 (7.7%) patients were hospitalised as a result of neutropenic sepsis. Conclusions: The results of this named patient programme over a two year timespan confirm that docetaxel is an effective chemotherapy option in patients with locally advanced and/or metastatic breast cancer, including an 'anthracycline refractory' population.
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  • 76
    ISSN: 1569-8041
    Keywords: breast cancer ; dose-intensity ; epirubicin ; G-CS/kwd〉 ; vinorelbine ; weekly schedule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: This study was designed to explore the effectiveness and tolerability of a weekly regimen of epirubicin and vinorelbine plus granulocyte colony-stimulating factor (G-CSF). Patients and methods: Fifty-two patients with previously untreated advanced breast cancer were treated with epirubicin (25 mg/m2/week) and vinorelbine (25 mg/m2/week) with G-CSF support, for 24 consecutive weeks. Results: The median number of courses per patient was 22 (range 10–24). The administered dose intensity was 23 mg/m2 for both epirubicin and vinorelbine. Ten complete responses (19%) and 30 partial responses (58%) were obtained, for an overall response rate of 77%. None of the patients progressed during treatment. The median response duration and time to progression were both 10 months. A total of 1065 courses were assessed for toxicity. Grade 3 neutropenia was the most common toxic manifestation, (39% of patients), without febrile neutropenia or neutropenic sepsis. Two patients had grade 3 cardiac toxicity, which regressed without sequelae. Median survival was 31 months, with a median follow-up of 24 months (range 9–40). Conclusions: Owing to its effectiveness and tolerability, the weekly regimen of epirubicin and vinorelbine plus G-CSF may represent an acceptable alternative for patients with untreated metastatic breast cancer. It could be tested in the adjuvant and neoadjuvant setting.
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  • 77
    ISSN: 1569-8041
    Keywords: breast cancer ; doxorubicin ; paclitaxel-anthracycline combination ; schedule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: We and others have demonstrated the antineoplastic efficacy of paclitaxel as a single agent in metastatic breast cancer. We performed this phase I trial to evaluate the combination of paclitaxel with doxorubicin. Patients and methods: Eligible patients had measurable or evaluable metastatic breast cancer for which this was the initial cytotoxic treatment. They may have received adjuvant chemotherapy with other drugs. The study had four parts. In part 1, the patients received paclitaxel by 24-hour infusion followed by doxorubicin by 48-hour infusion. The paclitaxel dose was to be escalated from a starting dose of 125 mg/m2, and the doxorubicin dose was to remain constant at 60 mg/m2 with treatment repeated every three weeks. The results of part 1 prompted part 2 which was a study of the reverse sequence. Part 3 was a formal study of pharmacology and has been reported (J Clin Oncol 14: 2713–21, 1996). In part 4, patients received doxorubicin 50 mg/m2 by bolus followed by paclitaxel 150 mg/m2 by 24-hour infusion for courses 1 and 2. In all subsequent courses doxorubicin was administered by 48-hour infusion. All patients in all four parts of the study had baseline cardiac scans. All patients received standard premedication for paclitaxel. Results: Forty-eight patients were treated in all four parts of the study. In part 1 (10 patients), the maximum tolerated dose (MTD) was paclitaxel 125 mg/m2/24 hours followed by doxorubicin 48 mg/m2/48 hours as defined by dose-limiting mucositis and neutropenic fever which occurred at the starting dose. For part 2 (21 patients), the MTD was doxorubicin 60 mg/m2/48 hours followed by paclitaxel 160 mg/m2/24 hours. In part 4 (seven patients), the MTD was doxorubicin 50 mg/m2/bolus followed by paclitaxel 135 mg/m2/24 hours. In parts 2 and 4, the dose-limiting toxic effect was neutropenia. Of the entire cohort of 48 patients, seven (15%) had a complete response (one persists at five years without intervening therapy), 26 (54%) had a partial response for an objective response rate of 69% (95% confidence interval (95% CI): 54%–81%). The median follow-up of all living patients is 38+ months (range 20+ to 62+); the median response duration is seven months (range 2–33.7+); the median overall survival is 20.5 months (range 5–54+). The median time to progression is 9.6 months (range 1–33.7+ months). Two patients developed congestive heart failure, one at 24 months after her final dose of doxorubicin which amounted to a cumulative lifetime total doxorubicin dose of 870 mg/m2, one after a total of 660 mg/m2. In both, cardiac symptoms were controlled with medications. Conclusions: The combination of paclitaxel/24 hours with doxorubicin/48 hours is an effective antineoplastic treatment for metastatic breast cancer. However, the incidence of complete response, the median overall survival, and time to progression were not greater than for standard doxorubicin-based combinations. Additionally, a sequence-dependent interaction between paclitaxel and doxorubicin, given in the schedule described here, was defined. Other strategies and schedules should be evaluated to maximize the antineoplastic efficacy of these two potent agents.
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  • 78
    ISSN: 1569-8041
    Keywords: 5-fluorouracil ; breast cancer ; neoadjuvant ; primary chemotherapy ; vinorelbine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Biological considerations support the use of primary chemotherapy in operable breast cancer; and despite wide variations of used regimens, clinical studies consistently show a significant tumor response allowing breast conservation in many patients otherwise canditates for mastectomy. We investigated the efficacy and the acceptance of a combination chemotherapy with vinorelbine, 5-fluorouracil and high-dose folinic acid in operable breast cancer with favorable prognostic factors and tested the relationship of hormone receptor status, Ki67, p53, c-erbB2 and bcl-2 with treatment response. Patients and methods: Thirty-nine patients (median age 51 years, range 36–71 years), eight with T1, twenty-eight with T2 and two with T3 lesions, were treated with 5-fluorouracil (350 mg/m2, i.v. on day 1 to 3) preceded by folinic acid (100 mg/m2 i.v. on day 1 to 3) and vinorelbine, given on days 1 and 3 at the dose of 20 mg/m2 (FLN regimen). Therapy was administered on an outpatient basis every three weeks. Non responders had surgery after three courses, while complete or partial responders underwent surgery after six courses. All but one were evaluable for response and toxicity. Results: Objective responses were observed in 23 of the 38 evaluable patients (61%; 95% CI: 46%–76%): three complete responses (8%) and 20 partial responses (53%). Fifteen patients (39%) had stable disease, of whom nine (23%) had minor response. None of the patients had disease progression during treatment. Objective responses were significantly associated with no expression of estrogen and/or progesteron receptors and 〉50% decrease in Ki67 after induction chemotherapy. Tolerance was excellent and none of the patients experienced grade 2 alopecia. Conclusions: The ‘moderate’ efficacy of this regimen might be partially due to the selection of patients with high expression of steroid hormone receptors and low proliferation rate, which have an unfavorable impact on response to this chemotherapy.
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  • 79
    ISSN: 1569-8041
    Keywords: breast cancer ; cardiotoxicity ; cyclophosphamide ; epirubicin ; high dose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: To prospectively evaluate the long term cardiac effects of high-dose epirubicin and cyclophosphamide given to women with early stage, poor prognosis breast cancer. Patients and methods: Women with stage 2 breast cancer and 10+ nodes or 4+ nodes and estrogen receptor negative tumor, or stage 3 breast cancer received three cycles of epirubicin 200 mg/m2 and cyclophosphamide 4 gm/m2 with peripheral blood progenitor cell and filgrastim support. Treatment was given every 28 days (n = 79) or 21 days (n = 20). Fifty patients received radiotherapy to the chest wall or breast, 25 of to the left side. Patients were assessed clinically regularly during chemotherapy and at least three times yearly after completion of treatment. Cardiac left ventricular ejection fraction (LVEF) was assessed by radionuclide scan before therapy, after each cycle of chemotherapy, three months and six months after completion of chemotherapy, and yearly thereafter until relapse. Results: Ninety-nine women were treated, and 92 completed all three cycles of chemotherapy. The median age was 43 years (range 24 to 60 years). All patients were included in this analysis. The median relapse-free survival was 39 months (11 to 68 months). There was a significant fall in LVEF during chemotherapy. In general, there was no further deterioration in cardiac function from the third month after cessation of treatment, however there was substantial variation between individuals. 35 patients had at least one LVEF measure less than normal (〈50%), but the LVEF returned to normal in 20 of these with further follow-up. Cardiac dysfunction was not increased in women who received radiotherapy and was not different between cohorts given chemotherapy every three or every four weeks. One patient died of acute myocardial necrosis following the third cycle of chemotherapy. Two patients developed clinical evidence of cardiac failure, and another had radiological signs but was asymptomatic. One woman died of progressive cardiac failure, one recovered clinically but also developed recurrent breast cancer, while the third recovered after commencement of medical therapy. Conclusions: During follow-up after high-dose epirubicin and cyclophosphamide as delivered in this study, the LVEF fell to below normal in approximately one third of patients. However, in over half of these patients the LVEF subsequently recovered to the normal range, and the incidence of clinically evident chronic cardiac failure was low. Further follow-up is required to assess the long- term safety. A randomized comparison with standard-dose anthracycline-based chemotherapy is needed to determine whether this regimen is associated with an increased risk of clinical cardiac toxicity.
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  • 80
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Intrazerebrale Blutung ; Magnetresonanztomographie ; Hämosiderin ; Key words Intracerebral hematome ; Magnetic resonance imaging ; Hemosiderin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Increased use of gradient echo T2*- weighted gradient echo sequences in magnetic resonance imaging (MRI) of patients suffering from primary ICH called attention to foci of signal loss which were suggested to represent remnants of cerebral microbleeds. In a post mortem correlative MR and histopathological study we provide support for this notion. We found areas of signal loss on gradient echo T2*-weighted sequences in 7 out of 11 brains of patients who had died of intracerebral hematoma. Histopathologically, these areas represented hemosiderin deposits indicating previous extravasation of blood. To provide data about the prevalence of these MRI findings in a healthy elderly population a subgroup of participants of the Austrian Stroke Prevention Study was analyzed. We detected foci of signal loss on gradient echo T2*-weighted sequences in 18 out of 280 volunteers (6,4%). MR-based evidence of previous microbleeds may indicate a potentially higher risk of suffering from intracerebral bleeding which could have therapeutic implications for the treatment of acute stroke and for secondary prevention. This hypothesis will have to be tested in future prospective trials.
    Notes: Zusammenfassung Vermehrte Anwendung T2*-gewichteter Gradienten-Echo-Sequenzen bei Magnetresonanztomographie- (MRT-) Untersuchungen von Patienten nach einem intrazerebralen Hämatom machte auf kleine, hypointense Areale aufmerksam, von denen bisher nur angenommen wurde, daß sie abgelaufene Mikroblutungen darstellen. In einer Post-mortem-Studie mit MRT und vergleichenden histopathologischen Untersuchungen zeigen wir Daten, die diese Hypothese stützen. Bei 7 von 11 Patienten, die an primärem intrazerebralem Hämatom verstorben waren, fanden sich hypointense Areale in T2*-Gradienten-Echo-Sequenzen. Histopathologisch zeigten diese Areale Hämosiderin-Ablagerungen, welche auf abgelaufene Blutungen hinweisen. Um Aussagen über die Prävalenz dieser MRT-Befunde in einem Kollektiv klinisch unauffälliger Probanden mittleren Alters machen zu können, wurden Teilnehmer derÖsterreichischen Schlaganfall-Vorsorge-Studie untersucht. Bei 18 von 280 Probanden (6,4%) fanden sich Signalhypointensitäten in T2*-Gradienten-Echo-Sequenzen. Der MR-tomographische Nachweis abgelaufener Mikroblutungen könnte ein Hinweis auf ein erhöhtes zerebrales Blutungsrisiko sein, was therapeutische Konsequenzen für die primäre Therapie und Sekundärprophylaxe beim Schlaganfall haben könnte. Hierzu sind noch weitere prospektive Studien notwendig.
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  • 81
    ISSN: 1433-0458
    Keywords: Schlüsselwörter Schädelbasis ; Innerer Gehörgang ; Tumor ; Hämangiom ; Kernspintomographie ; Computertomographie ; Key words Skull-base tumors ; Internal auditory meatus ; Hemangiomas ; Magnetic resonance imaging ; Computed tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Hemangiomas of the skull base are rare neoplasms and are easily misdiagnosed as acoustic neuromas when occurring in the internal auditory canal. Among these tumors, ossifying hemangiomas are characterized histologically be newly formed bone tissue within their substance. We describe a 26-year old female patient who presented with left-sided sensorineural hearing loss and tinnitus. T2-weighted magnetic resonance imaging demonstrated a bright space-occupying lesion of the internal auditory canal with extension to the geniculate ganglion. Bony erosions of the internal auditory canal were proved by high-resolution computed tomography. A hemangioma was suspected preoperatively and was resected via a middle cranial fossa approach. Histologically, new bone formations were found in a cavernous hemangioma. In general, radiologic findings can suggest a hemangioma of the internal auditory canal and help to differentiate it from acoustic neuroma. Based on the histological findings of intratumoral bone formation, the hemangioma in our patient was classified as an ossifying hemangioma. However, reactive bone formation at the borders of a tumor in the internal auditory canal can also be mistaken as new intratumoral bone formation.
    Notes: Zusammenfassung Hämangiome der Schädelbasis sind insgesamt seltene Tumoren, die im Bereich des inneren Gehörgangs insbesondere mit dem wesentlich häufigeren Akustikusneurinom verwechselt werden können. Das ossifizierende Hämangiom repräsentiert eine Sonderform in der Gruppe der Hämangiome und ist histopathologisch durch intratumorale Knochenneubildungen gekennzeichnet. Es wird von einem kavernösen Hämangiom des linken inneren Gehörgangs bei einer 26jährigen Patientin berichtet, welches zu einer progredienten sensorineuralen Hörminderung und Tinnitus geführt hatte. Bei T2-gewichteter kernspintomographischer Darstellung einer signalreichen Neubildung im inneren Gehörgang mit computertomographisch evidenten Knochendestruktionen am Gehörgangsboden war präoperativ die Abgrenzung von einem Akustikusneurinom möglich. Über einen transtemporalen Zugang konnte die vaskuläre Neubildung reseziert werden. Histopathologisch waren Knochenneubildungen in einem kavernösen Hämangiom zu erkennen. Die radiologischen Befunde ermöglichen präoperativ die Abgrenzung eines Hämangioms vom Akustikusneurinom. Aufgrund des Nachweises von Knochenneubildungen in den histologischen Schnittpräparaten des Tumors ist die Einordnung des kavernösen Hämangioms als ossifizierendes Hämangiom naheliegend. Neben der Wertung der histologisch nachgewiesenen Knochenneubildungen als intratumorale Ereignisse muß auch an die Möglichkeit einer in den Schnittpräparaten vorgetäuschten intratumoralen Knochenneubildung durch den Anschnitt reaktiver Knochenneubildungen am destruierten Gehörgangboden gedacht werden.
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  • 82
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    Der Nervenarzt 70 (1999), S. 679-687 
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Perfluorcarbon-Emulsionen ; Perfluorcarbone ; Neuroprotektion ; Ischämie ; Reperfusionsschaden ; Kernspintomographie ; Tumorversorgung ; Key words Perfluorocarbon emulsions ; Perfluorochemicals ; Cerebral protection ; Ischemia ; Reperfusion injury ; Magnetic resonance imaging ; Tumor oxygenation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary For the ussage as blood substitutes perfluorocarbons (PFC) have been developed as artificial oxygen carriers. In addition they may have potency for protective use in ischemic tissue. Formulation improvement achieved higher oxygen carrying capacity and better compatibility than the first generation of PFC. Preclinical studies have been performed in animal heart and brain. Former and progressed emulsification for intravascular use have been investigated for infarction and reperfusion injury. This investigations are reviewed and the potencies for the use of PFC in neurology, neurosurgery, diagnostics today and in the future are emphasized.
    Notes: Zusammenfassung Perfluorcarbone (PFC) sind künstliche Sauerstoffträger, die ursprünglich als Blutersatzstoffe entwickelt wurden. Auf Grund ihrer spezifischen Eigenschaften ist darüber hinaus ihr Einsatz bei ischämischen Perfusionsstörungen von potentiellen Nutzen. Neuere Perfluorcarbonpräparationen verfügen über eine höhere Sauerstofftransportkapazität und sind mit weniger Nebenwirkungen behaftet als die PFC der ersten Generation. Ältere und neuere PFC-Emulsionen, die für die intravaskuläre Applikation geeignet sind, wurden und werden im Tierversuch für den Einsatz in ischämischen Gebieten des Herzens und des Gehirns untersucht. In dieser Arbeit werden präklinische Studien bei Infarkten und Reperfusionsschaden beschrieben und potentielle Nutzungsmöglichkeiten dieser Substanzgruppe für diese Indikationsstellung diskutiert.
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  • 83
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Intrakranielle Blutung ; Magnetresonanztomographie ; T2*-gewichtete Gradienten-Echo-Sequenz ; Hypertensive zerebrale Mikroangiopathie ; Zerebrale Amyloidangiopathie ; Zerebrale Kavernome ; Key words Intracerebral hemorrhage ; Magnetic resonance imaging ; Cerebral amyloid angiopathy ; Hypertensive cerebral microangiopathy ; Cerebral cavernoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary In four patients presenting with acute nontraumatic intracerebral or intraspinal hemorrhage, T2*-weighted gradient-echo MRI showed numerous residual hemosiderin deposits due to old intracerebral hemorrhages that were missed on initial CT and spin-echo MRI. The demonstration of additional chronic bleedings and their anatomical distribution provided important diagnostic information. In a hypertensive patient, the hemosiderin deposits were most pronounced within deep brain structures suggesting hypertensive cerebral microangiopathy. In a second patient, the cortico-subcortical distribution of the hemorrhages was typical of cerebral amyloid angiopathy. In a third patient, the diffuse distribution including spinal bleeding, the marked calcification, and the characteristic appearance on spin-echo MRI were consistent with multiple cavernomas. In another patient with cerebral and spinal hemorrhage, T2*-weighted gradient-echo MRI revealed new subclinical hemorrhages during follow-up. Based on these findings, we recommend that T2*-weighted gradient-echo MRI of the brain should be performed in all patients with acute intracranial and spinal bleedings.
    Notes: Zusammenfassung Bei 4 Patienten mit akuten intrazerebralen oder intramedullären Blutungen konnte die T2*-gewichtete Gradienten-Echo-Magnetresonanztomographie (“Häm”-Sequenz) multiple intrakranielle Hämosiderinablagerungen als Beleg für in der Vergangenheit abgelaufene Hirnblutungen nachweisen. Diese klinisch stummen Blutungen waren sowohl der Computertomographie als auch der Spin-Echo-Magnetresonanztomographie entgangen. Bei 3 Patienten ermöglichte das Verteilungsmuster der als Signalauslöschungen dargestellten Hämosiderinablagerungen eine bessere Eingrenzung der Blutungsursache. Bei einem Patienten mit arterieller Hypertonie legten die vorwiegend in den tieferen Hirnstrukturen lokalisierten Blutungen eine hypertensive zerebrale Mikroangiopathie nahe. Bei einem Patienten mit rezidivierenden Lobärhämatomen sprach die kortikosubkortikale Lokalisation der Blutungen für das Vorliegen einer zerebralen Amyloidangiopathie. Bei einer Patientin mit spinaler Blutung stellten wir aufgrund des diffusen Verteilungsmusters, der starken Verkalkungstendenz und des heterogenen Signalverhaltens der Blutungsherde in der Spin-Echo-Magnetresonanztomographie die Diagnose multipler zerebrospinaler Kavernome. Bei einem Patienten mit zerebralen und spinalen Blutungen erlaubte die “Häm”-Sequenz keine diagnostische Einordnung, erwies sich aber als sensitives Instrument in der Verlaufskontrolle. Bei allen Patienten mit spontaner intrazerebraler oder intraspinaler Blutung sollte im Rahmen der bildgebenden Diagnostik eine “Häm”-Sequenz durchgeführt werden.
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  • 84
    ISSN: 1437-9813
    Keywords: Key words Cholangiography ; Choledochal cyst ; Cholestasis ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Magnetic resonance cholangiopancreaticography (MRCP) was used to visualize the biliary tract in two children, aged 7 weeks and 10 years, with a choledochal cyst. MRCP was successful in both cases and the findings were confirmed by intraoperative cholangiography.
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  • 85
    ISSN: 1432-2161
    Keywords: Key words Joint ; Knee ; Anatomy ; Magnetic resonance imaging ; Posteromedial corner ; Intra-articular contrast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. The objective of this study was to illustrate the magnetic resonance (MR) image appearance of the structures of the posteromedial ”corner” of the knee with particular emphasis on the anatomy and differentiation between the medial collateral ligament and the posterior oblique ligament. Design. Six cadaveric knee specimens underwent MR imaging, before and following instillation of intra-articular contrast material. The knees were sectioned in the axial, coronal, and coronal oblique planes and the gross morphology of the posteromedial corner and surrounding structures was studied and correlated with the MR images. Patients. The human cadaveric specimens were from two female and four male patients (age at death, 72–86 years; average, 78 years). Results and conclusions. The contrast-enhanced sequences and the coronal oblique images allowed for improved visualization of the structures.
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  • 86
    ISSN: 1432-2161
    Keywords: Key words Bone tumor ; Chondrosarcoma ; CT ; Magnetic resonance imaging ; Tumor of the ankle ; Tumor of the foot
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The foot is an uncommon location for chondrosarcoma. The presentation, diagnosis, pathological findings, surgical treatment and follow-up of three patients with chondrosarcoma in this rare location are presented. Though nonspecific, MR imaging findings were of aid in the diagnosis and treatment planning of these patients. If the diagnosis of this tumor is rapidly made, a tumor excision instead of limb amputation may be sufficient treatment at surgery.
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  • 87
    ISSN: 1126-5442
    Keywords: Key words Carbon monoxide poisoning ; Delayed neurologic sequelae ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The clinical and neuroradiological outcome of carbon monoxide (CO) intoxication was evaluated prospectively in 30 patients over a follow-up period of 3 years. Among the patients studied, 22 had been acutely exposed to CO while 8 were chronically exposed. One month after CO poisoning, 12 of the 22 patients with acute intoxication showed magnetic resonance imaging (MRI) abnormalities: 6 also had neurological sequelae and 6 were asymptomatic. The remaining 10 patients showed neither MRI abnormalities nor neurological sequelae. During the 3-year follow-up, 4 of the patients with both MRI abnormalities and neurological sequelae improved in both clinical features and MRI findings. One of the 6 asymptomatic patients with MRI abnormalities developed a progressive cognitive impairment 2 months after acute intoxication, with a concomitant severe worsening of the MRI lesions. Among the 10 patients with neither MRI abnormalities nor neurological sequelae, only 1 developed neurological sequelae after a clear period of 4 months. In the group of patients who experienced chronic CO intoxication, only 1 presented with a neuropsychiatric syndrome which improved at follow-up. Brain MRI showed white matter lesions which remained unchanged at control scan after 1 year. In conclusion, we observed that some patients with severe CO poisoning and neurological sequelae may fully regain normal functions after approximately 1 year. The presence of MRI lesions 1 month after CO poisoning did not accurately predict the subsequent outcome. The observation of a clear period longer than the usual 2–40 day interval in 2 patients should be considered for careful planning of follow-up and for prognosis in CO-poisoned patients.
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  • 88
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    Italian journal of neurological sciences 20 (1999), S. 183-186 
    ISSN: 1126-5442
    Keywords: Key words Behçet's disease ; Optic neuropathy ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Orbital magnetic resonance imaging demonstrated increased signal of the optic nerve in short time inversion recovery (STIR) images of two young women with unilateral visual blurring. In both, recurrent oral and genital ulcerations and papulopustular lesions appeared within the next 14–15 months, respectively, allowing a diagnosis of Behçet's disease. Optic neuropathy may be an early manifestation of Behçt's disease and clinical follow-up is crucial for its diagnosis.
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  • 89
    ISSN: 1432-1327
    Keywords: Key words Contrast agents ; Gadolinium complexes ; Magnetic resonance imaging ; Relaxivity ; Tetraazamacrocycles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  The ligand DOTASA was designed and synthesized in the aim of obtaining a kinetically and thermodynamically stable Gd(III) chelate which, through its uncoordinated carboxylate function, will provide an efficient pathway to couple the complex to bio- or macromolecules without affecting the coordination pattern of DOTA. Furthermore, it allows us to study the influence of an extra carboxylate arm on the parameters determining proton relaxivity in comparison to the commercial agent [Gd(DOTA)(H2O)]–. A combined variable-temperature 17O NMR, EPR and nuclear magnetic relaxation dispersion study on the Gd(III) chelate resulted in k 298 ex=(6.3±0.2)×106 s–1 for the water exchange rate and τ298 R=125±2 ps for the rotational correlation time. The slight increase in both k 298 ex and τ298 R, as compared to those for [Gd(DOTA)(H2O)]–, is attributed to the presence of the extra negative charge. The longer rotational correlation time results in a proton relaxivity of 5.03 mM–1 s–1 for [Gd(DOTASA)(H2O)]2–, which is approximately 30% higher than that for [Gd(DOTA)(H2O)]–. The increased water exchange rate of [Gd(DOTASA)(H2O)]2– has no consequence for proton relaxivity since this latter is exclusively limited by fast rotation for both complexes. However, for slowly rotating macromolecular agents, which contain a covalently coupled DOTASA unit instead of a coupled DOTA, this increased exchange rate will have a significant positive effect.
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  • 90
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    Experimental brain research 124 (1999), S. 271-272 
    ISSN: 1432-1106
    Keywords: Key words Brain ; Magnetic resonance imaging ; Microemboli ; Microischemia ; N-tert-butyl-α-phenylnitrone ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Dementia due to cerebral ischemic lesions is relatively common in the elderly. Since many of these lesions are probably caused by emboli, studying emboli-induced cerebral lesions in rabbits should, hopefully, provide information that is useful when searching for a means of preventing and treating vascular dementia in humans. Using magnetic resonance imaging we have found that N-tert-butyl-α-phenyl-nitrone (a free radical scavenger) reduced the number of emboli-induced cerebral microinfarctions in the rabbit cortex but did not have any impact on the number of infarctions found in the subcortical structures. The results suggest that significant amount of free radicals are produced in the ischemic foci located in the cortex, but not in the ischemic foci located in the subcortical structures. This finding may be of importance when considering treatments for cerebral ischemia in humans.
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  • 91
    ISSN: 1432-1084
    Keywords: Key words: Liver ; diseases ; Peliosis ; Computed tomography ; Angiography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Peliosis hepatis is an uncommon liver condition characterized by blood-filled cavities. We report the CT, angiographic and MR features of a case of peliosis hepatis with no obvious etiology and spontaneously regressing hemorrhagic necrosis. Helical CT showed multiple peripheral low-density regions with foci of spontaneous high density suggesting the presence of blood component. On MR imaging, the multiple peripheral lesions were hypointense on T1-weighted and hyperdense on T2-weighted images, with bright foci on all sequences suggesting subacute blood. Angiography showed no evidence of tumor or vascular malformation; multiple nodular vascular lesions filling in the parenchymal phase and persisting in the venous phase suggested blood-filled cavities. Pathological examination showed blood-filled spaces with no endothelial lining, characteristic of the parenchymal type of peliosis. Knowledge of the imaging features of hemorrhagic necrosis due to peliosis hepatis is important since it can be responsive to antibiotic therapy. Furthermore, differentiating hemorrhagic necrosis from hepatic abscess avoids dangerous and sometimes fatal percutaneous drainage.
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  • 92
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    Neuroradiology 41 (1999), S. 729-731 
    ISSN: 1432-1920
    Keywords: Key words DIDMOAD syndrome ; Wolfram syndrome ; substantia nigra ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Wolfram syndrome (DIDMOAD) is a rare diffuse neurodegenerative disorder characterised by diabetes insipidus, diabetes mellitus, optic atrophy, deafness, and a wide variety of abnormalities of the central nervous system, urinary tract and endocrine glands. It may be familial or sporadic. Reported features on MRI of the brain are absence of the physiological high signal of the posterior lobe of the pituitary, shrinkage of optic nerves, chiasm and tracts, atrophy of the hypothalamic region, brain stem, cerebellum, and cerebral cortex. We report a 12-year-old girl with a 5-year history without brain stem, cerebellar or cerebral atrophy. MRI showed an unusual feature: a focus of high signal on PD- and T2-weighted images in the right substantia nigra. This is consistent with previously reported neuropathological post-mortem studies, but has never been reported in vivo.
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  • 93
    ISSN: 1432-1920
    Keywords: Key words Parkinson's disease ; Differential diagnosis ; Magnetic resonance imaging ; Signal intensity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A reduction in signal in the basal ganglia on T2-weighted images is said to correlate with a poor response to L-DOPA and may help to identify patients with nonidiopathic parkinsonism. Our aim in this prospective study was to use the contrast-to-noise ratio of the MRI signal on T2-weighted images in various parts of the basal ganglia in 43 patients with de novo parkinsonism. Signal intensity measurements were compared to the response to the dopamine agonist apomorphine and dopamine-D2 receptor binding obtained by 3-iodo-6-methoxybenzamine single-photon emission computed tomography (IBZM-SPECT). A reduced contrast-to-noise ratio in the putamen correlated significantly with a negative response to apomorphine and reduced striatal IBZM binding. No additional signal intensity measurement correlated with response to apomorphine or specific IBZM binding. However, there was a considerable overlap of contrast-to-noise ratios between patients with a positive or negative response to apomorphine or normal and reduced IBZM binding. We suggest that semiquantitative assessment of signal intensity in the putamen shows a significant reduction in patients with probably nonidiopathic parkinsonism compared with patients with probably idiopathic parkinsonism. However, this method does not exclude idiopathic parkinsonism in a given patient.
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  • 94
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    Neuroradiology 41 (1999), S. 140-143 
    ISSN: 1432-1920
    Keywords: Key words Haemangiomas ; head and neck ; Magnetic resonance imaging ; Magnetic resonance angiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We evaluated the clinical effectiveness of contrast-enhanced three-dimensional (3D) magnetic resonance angiography (MRA) for diagnosing head and neck haemangiomas. We studied six patients using a magnetization prepared rapid acquisition gradient-echo (MP-RAGE) sequence on a 1.5-T system. Conventional T1- and T2-weighted and contrast-enhanced images were also obtained. The images were compared with histological findings. In four cavernous haemangiomas, a mass was partially visible as an enhancing lesion on the early phase of MRA, and was completely visible as a larger enhancing lesion in the late phase, showing slow blood flow. In two capillary haemangiomas, a mass was completely visible in the early phase showing fast flow. In all patients, MRA clearly showed both the haemangiomas and the external carotid artery branches. MRA allowed assessment of the relationship between the haemangiomas and the feeding arteries, and of the haemodynamics.
    Type of Medium: Electronic Resource
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  • 95
    ISSN: 1432-1920
    Keywords: Key words Hypernatraemia ; Myelinolysis ; extrapontine ; Computed tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The neuroimaging findings in an infant with hypernatremic dehydration are presented. Brain parenchymal haemorrhage and extensive multiple infarcts were present in the acute stage. Follow-up CT showed bilateral, symmetrical changes presumed to indicate extrapontine myelinolysis in the thalamus and globus pallidus. MRI confirmed sparing of the pons. Only three previous cases of neuroimaging abnormalities due to hypernatraemia have been described in the radiological literature.
    Type of Medium: Electronic Resource
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  • 96
    ISSN: 1432-1920
    Keywords: Key words Hereditary caeruloplasmin deficiency ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We present two patients with hypocaeruloplasminaemia and a heteroallelic caeruloplasmin gene mutation (HypoCPGM). These patients had diabetes mellitus and tremor of the hands, respectively. T2-weighted fast spin-echo MRI showed mildly reduced intensity of the putamen, much more marked on echo-planar imaging.
    Type of Medium: Electronic Resource
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  • 97
    ISSN: 1432-1920
    Keywords: Key words Neurofibromatosis type 1 (NF1) ; Optic glioma ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report two children with neurofibromatosis type 1 showing enhancing masses on MRI suggesting neoplasms in the chiasm and hypothalamic region. In both patients no visual or endocrinal dysfunction was present. On serial MRI spontaneous partial remission was found, implying that a cautious approach to therapeutic management of similar cases should be taken.
    Type of Medium: Electronic Resource
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  • 98
    ISSN: 1432-1920
    Keywords: Key words Behçet's syndrome ; Central nervous system ; Magnetic resonance imaging ; Brain ; vasculitis ; Multiple sclerosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two neuroradiologists reviewed MRI studies of 34 patients with neuro-Behçet's disease (NBD), 22 with multiple sclerosis (MS) and 7 with systemic lupus erythematosus (SLE) with central nervous system involvement, masked to the clinical diagnosis, age and sex of the patients. Of the patients with NBD 12 were in an acute attack; the others had chronic disease. MRI was assessed using a set of criteria, looking at atrophy, the site of discrete parenchymal lesions, regions of predominant involvement and the extent of the lesion(s). The observers also made a guess at the clinical diagnosis. The brain stem and/or basal ganglia were the most predominantly involved sites in all patients with acute NBD; 75 % of these lesions were large and confluent, mainly extending from the brain stem to the diencephalon and basal ganglia. However, in chronic cases, the predominant involvement was in the brain stem and/or basal ganglia in only 36 %, and in cerebral hemisphere white matter in another 36 %; 27 % of these patients showed no parenchymal lesion. Hemisphere white-matter lesions were equally distributed between periventricular and other areas in NBD, while in MS more were periventricular, and in SLE more were nonperiventricular. Brain-stem atrophy was seen in 21 % of patients with NBD, with a specificity of 96.5 %. In the absence of cortical atrophy, its specificity was 100 %. The attempt at making a radiological diagnosis was successful in all cases of acute NBD and 95.5 % of patients with MS, but in only 40 % of patients with chronic NBD. Most of this latter groups MRI studies were interpreted as MS. An extensive lesion involving the brain stem and basal ganglia seemed to be diagnostic of acute NBD. However, hemisphere white-matter lesions could not be differentiated from those in MS.
    Type of Medium: Electronic Resource
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  • 99
    ISSN: 1432-1920
    Keywords: Key words Virchow-Robin spaces ; Magnetic resonance imaging ; Childhood migraine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Virchow-Robin spaces (VRS) are pia-lined extensions of the subarachnoid space which surround penetrating arteries as they enter the brain on its surface. Using high-resolution MRI, which shows small penetrating arteries, we studied a possible association of accentuated VRS in children with tension-type headache (TTH) or migraine. We studied 58 children aged 3–14 years (mean 10.8 years) with a clinical diagnosis of migraine (31) or TTH (27), who underwent cerebral MRI, and 30 headache-free patients of the same age (mean 10.2 years) and 30 adult migraineurs with postpubertal onset of symptoms, who served as controls. The images were reviewed for structural abnormalities in the regions of the small penetrating arteries. Accentuated VRS were found in 61 % of the children with migrainous headaches and in 22 % of children of those with TTH. Prominent VRS were seen in 27 % of the control children and in only 13 % of the adults. Small infarcts and gliosis were rare in children with or without headache, but were seen in 30 % of the adult migraineurs. Our findings show that accentuated VRS are significantly more common in children with migraine than in those with TTH or headache-free controls. Detection of accentuated VRS may therefore enhance differential diagnosis of primary headaches in children, contributing to an improvement in management.
    Type of Medium: Electronic Resource
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  • 100
    ISSN: 1432-1920
    Keywords: Key words Brain ischaemia ; Brain ; infarct ; Magnetic resonance imaging ; Magnetic resonance angiography ; Pulse sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the hyperacute phase of stroke, occluded vessels can be seen as high signal on fast-FLAIR images or as absence of flow-related enhancement in maximum-intensity projection (MIP) MR angiography (MRA). To compare these techniques, we examined 53 patients within 6 h of a stroke, using a standardised MRI protocol including fast-FLAIR and 3D time-of-flight TOF MR to detect vessel occlusion or reduced flow corresponding to the suspected ischaemic territory. Brain infarcts were confirmed on MRI after 1–5 days in 41 cases (77 %). The overall accuracy of 3D-TOF MRA was 68 % and sensitivity, specificity, positive and negative predictive values were 67 %, 71 %, 87 %, and 43 % respectively. Values for the fast-FLAIR sequence were: 65 %, 85 %, 93 % and 44 %, with an overall accuracy of 70 %. The fast-FLAIR sequence was thus able to show occluded vessels or reduced flow with about the same accuracy as 3D-TOF MRA and enabled better prediction of the ischaemic area.
    Type of Medium: Electronic Resource
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