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  • 2000-2004  (151)
  • 1860-1869
  • 2000  (151)
  • Children  (91)
  • Cell & Developmental Biology
  • Life and Medical Sciences
  • ddc:000
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  • 2000-2004  (151)
  • 1860-1869
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  • 1
    Publication Date: 2014-02-26
    Description: One important step in the fabrication of silicon-based integrated circuits is the creation of semiconducting areas by diffusion of dopant impurities into silicon. Complex models have been developed to investigate the redistribution of dopants and point defects. In general, numerical analysis of the resulting PDEs is the central tool to assess the modelling process. We present an adaptive approach which is able to judge the quality of the numerical approximation and which provides an automatic mesh improvement. Using linearly implicit methods in time and multilevel finite elements in space, we are able to integrate efficiently the arising reaction-drift-diffusion equations with high accuracy. Two different diffusion processes of practical interest are simulated.
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  • 2
    Publication Date: 2014-02-26
    Description: Uncoupling-coupling Monte Carlo (UCMC) combines uncoupling techniques for finite Markov chains with Markov chain Monte Carlo methodology. By determining almost invariant sets of the associated Markov operator, the Monte Carlo sampling splits by a hierarchical annealing process into the essential regions of the state space; therefore UCMC aims at avoiding the typical metastable behavior of Monte Carlo techniques. From the viewpoint of Monte Carlo, a slowly converging long-time Markov chain is replaced by a limited number of rapidly mixing short-time ones. The correct weighting factors for the various Markov chains are obtained via a coupling matrix, that connects the samplings from the different almost invariant sets. The underlying mathematical structure of this approach is given by a general examination of the uncoupling-coupling procedure. Furthermore, the overall algorithmic scheme of UCMC is applied to the $n$-pentane molecule, a well-known example from molecular dynamics.
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  • 3
    Publication Date: 2020-11-13
    Description: The traveling repairman problem (TRP) is a variant of the famous traveling salesman problem (TSP). The objective for the TRP is to minimize the latency, that is the the weighted sum of completion times of the cities, where the completion time of a city is defined to be the time in the tour before the city is reached. In the online traveling repairman problem (OLTRP) requests for visits to cities (points in a metric space) arrive online while the repairman is traveling. We analyze the performance of algorithms using competitive analysis, where the cost of an online algorithm is compared to that of an optimal offline algorithm. An optimal offline algorithm knows the entire request sequence in advance and can serve it with minimum cost. Recently, Feuerstein and Stougie presented a $9$-competitive algorithm for the OLTRP on the real line. In this paper we show how to use techniques from online-scheduling to obtain an $8$-competitive deterministic algorithm which works for any metric space. We also present a randomized algorithm which has a competitive ratio of $\frac{4}{\ln 2}\approx 5.7708$ against an oblivious adversary. All of our results also hold for the ``dial-a-ride'' generalization of the OLTRP, where objects have to be picked up and delivered by a server.
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  • 4
    Publication Date: 2020-11-13
    Description: In the online traveling salesman problem requests for visits to cities (points in a metric space) arrive online while the salesman is traveling. The salesman moves at no more than unit speed and starts and ends his work at a designated origin. The objective is to find a routing for the salesman which finishes as early as possible. Performance of algorithms is measured through their competitive ratio, comparing the outcome of the algorithms with that of an adversary who provides the problem instance and therefore is able to achieve the optimal offline solution. Objections against such omnipotent adversaries have lead us to devise an adversary that is in a natural way, in the context of routing problems, more restricted in power. For the exposition we consider the online traveling salesman problem on the metric space given by the non-negative part of the real line. We show that a very natural strategy is~$3/2$-competitive against the conventional adversary, which matches the lower bound on competitive ratios achievable for algorithms for this problem. Against the more ``\emph{fair adversary}'', that we propose, we show that there exists an algorithm with competitive ratio $\frac{1+\sqrt{17}}{4}\approx 1.28$ and provide a matching lower bound. We also show competitiveness results for a special class of algorithms (called zealous algorithms) that do not allow waiting time for the server as long as there are requests unserved.
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  • 5
    Publication Date: 2020-03-09
    Description: Regional hyperthermia, a clinical cancer therapy, is the main topic of the Sonderforschungsbereich Hyperthermia: Scientific Methods and Clinical Applications'' at Berlin. In recent years, technological improvements towards a better concentration of heat to the desired target region have been achieved. These include a rather sophisticated integrated software environment for therapy planning and a new hyperthermia applicator. In a next step, a detailed closed loop monitoring of the actual treatment is to be developed. For this purpose the hyperthermia applicator is combined with an MRI system, which will allow to check the positioning of the patients and to measure individual blood perfusion as well as the 3D temperature distribution. The measurements will then be employed for an on-line control of the whole treatment. In this intended setting, new fast feedback control algorithms will come into play.
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  • 6
    Publication Date: 2020-03-11
    Description: In diesem Artikel wird der Status des Projekts Kooperativer Bibliotheksverbund Berlin-Brandenburg beschrieben, der im November 1999 mit der KOBV-Suchmaschine seinen produktiven Betrieb aufgenommen hat. Die Recherchemöglichkeiten im WWW werden erläutert, Zugriffszahlen genannt und Entwicklungsperspektiven skizziert. Dieser Bericht entspricht der schriftlichen Fassung eines gleichnamigen Vortrages, der auf dem 1. Gemeinsamen Kongreß der Bundesvereinigung Deutscher Bibliotheksverbände e.V. und der Deutschen Gesellschaft für Informationswissenschaft und Informationspraxis e.V. Information und Öffentlichkeit gehalten wurde, der vom 20. bis 23. März 2000 in Leipzig stattfand.
    Keywords: ddc:000
    Language: German
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  • 7
    Publication Date: 2014-02-26
    Description: In this paper for the $M(n)/M(n)/s+GI$ system, i.e.\ for a $s$-server queueing system where the calls in the queue may leave the system due to impatience, we present new asymptotic results for the intensities of calls leaving the system due to impatience and a Markovian system approximation where these results are applied. Furthermore, we present a new proof for the formulae of the conditional density of the virtual waiting time distributions, recently given by Movaghar for the less general $M(n)/M/s+GI$ system. Also we obtain new explicit expressions for refined virtual waiting time characteristics as a byproduct.
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  • 8
    Publication Date: 2020-11-13
    Description: Several practical instances of network design problems require the network to satisfy multiple constraints. In this paper, we address the \emph{Budget Constrained Connected Median Problem}: We are given an undirected graph $G = (V,E)$ with two different edge-weight functions $c$ (modeling the construction or communication cost) and $d$ (modeling the service distance), and a bound~$B$ on the total service distance. The goal is to find a subtree~$T$ of $G$ with minimum $c$-cost $c(T)$ subject to the constraint that the sum of the service distances of all the remaining nodes $v \in V\setminus T$ to their closest neighbor in~$T$ does not exceed the specified budget~$B$. This problem has applications in optical network design and the efficient maintenance of distributed databases. We formulate this problem as bicriteria network design problem, and present bicriteria approximation algorithms. We also prove lower bounds on the approximability of the problem that demonstrate that our performance ratios are close to best possible
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  • 9
    Publication Date: 2014-02-26
    Description: Network loading problems occur in the design of telecommunication networks, in many different settings. The polyhedral structure of this problem is important in developing solution methods for the problem. In this paper we investigate the polytope of the problem restricted to one edge of the network (the edge capacity problem). We describe classes of strong valid inequalities for the edge capacity polytope, and we derive conditions under which these constraints define facets. As the edge capacity problem is a relaxation of the network loading problem, their polytopes are intimately related. We, therefore, also give conditions under which the inequalities of the edge capacity polytope define facets of the network loading polytope. Furthermore, some structural properties are derived, such as the relation of the edge capacity polytope to the knapsack polytope. We conclude the theoretical part of this paper with some lifting theorems, where we show that this problem is polynomially solvable for most of our classes of valid inequalities. In a computational study the quality of the constraints is investigated. Here, we show that the valid inequalities of the edge capacity polytope are not only important for solving the edge capacity problem, but also for the network loading problem, showing that the edge capacity problem is an important subproblem.
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  • 10
    Publication Date: 2014-02-26
    Description: Die Entwicklung einer bibliothekarischen Suchmaschine ist das technisch-organisatorische Herztück des Kooperativen Bibliotheksverbundes Berlin-Brandenburg (KOBV). Auf dem Wege über diese Innovation verfolgen die Länder Berlin und Brandenburg und ihre Bibliotheken das Ziel, ihr Bibliothekswesen zu erneuern und zu reorganisieren. Die Entwicklung der Suchmaschine ist für die Partner im KOBV-Projekt kein Selbstzweck, sondern nur Mittel zum Zweck - insbesondere, um die heterogene Welt der in Berlin und in Brandenburg eingesetzten integrierten Bibliotheksinformationssysteme harmonisch miteinender zu verbinden. Mit der KOBV-Suchmaschine sind informationstechnische Sichtweisen und Methoden entstanden, die sich potentiell auch auf die überregionale Arbeit des KOBV auswirken können und in Kooperation mit den Bibliotheksverbänden auf die Zusammenarbeit der Verbünde insgesamt. Der Artikel konzentriert sich am Beispiel der KOBV-Such¡ma¡schine auch auf diesen Aspekt. Auf die Bibliotheken kommen mit dem Internet und dem World Wide Web für sie neuartige Medien, Mittel und Aufgaben zu, in erster Linie aus dem Bereich der Wissenschaften und der wissenschaftlichen Fachgesellschaften. Die Herausforderung besteht darin, die neuen elektronischen Informationen und Angebote zu integrieren. Das Stichwort hierzu lautet digitale Bibliothek bzw. virtuelle Fachbibliothek. Auch zu der Diskussion um diese aktuelle Entwicklung will der Artikel einen Beitrag leisten.
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    Language: German
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  • 11
    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 on $10^4$ and $12^4$ lattices. As an indicator for decorrelation the topological charge is used.
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  • 12
    Publication Date: 2014-02-26
    Description: In this paper we describe the results of a computational study towards the (re)optimization of signaling transfer points (STPs) in telecommunication networks. The best performance of an STP is achieved whenever the traffic load is evenly distributed among the internal components. Due to the continuously changing traffic pattern, the load of the components has to be re-optimized on a regular basis. Besides the balancing objective also the number of rearrangements have to be taken into account. In this paper we present two alternative formulations to deal with both requirements. Computational results show that for both formulations (near) optimal solutions can be obtained within reasonable time limits.
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  • 13
    Publication Date: 2014-02-26
    Description: The structures and interaction energies of guanine and uracil quartets have been determined by B3LYP hybrid density functional calculations. The total interaction energy $\Delta$E$^{T}$ of the $\it{C}$$_{4h}$-symmetric guanine quartet consisting of Hoogsteen type base pairs with two hydrogen bonds between two neighbour bases is -66.07 kcal/mol at the highest level. The uracil quartet with C6-H6...O4 interactions between the individual bases has only a small interaction energy of -20.92 kcal/mol and the interaction energy of -24.63 kcal/mol for the alternative structure with N3-H3...O4 hydrogen bonds is only slightly more negative. Cooperative effects contribute between 10 and 25 \% to all interaction energies. Complexes of metal ions with G-quartets can be classified into different structure types. The one with Ca$^{2+}$ in the central cavity adopts a $\it{C}$$_{4h}$-symmetric structure with coplanar bases, whereas the energies of the planar and non-planar Na$^{+}$ complexes are almost identical. The small ions Li$^{+}$, Be$^{2+}$, Cu$^{+}$ and Zn$^{2+}$ prefer a non-planar $\it{S}$$_{4}$-symmetric structure. The lack of co-planarity prevents probably a stacking of these base quartets. The central cavity is too small for K$^{+}$ ions and therefore this ion favours in contrast to all other investigated ions a $\it{C}$$_{4}$-symmetric complex, which is 4.73 kcal/mol more stable than the $\it{C}$$_{4h}$-symmetric one. The distance 1.665 {\AA} between K$^{+}$ and the root mean squares plane of the guanine bases is approximately half of the distance between two stacked G-quartets. The total interaction energy of alkaline earth ion complexes exceeds the ones with alkali ions. Within both groups of ions the interaction energy decreases with an increasing row position in the periodic table. The B3LYP and BLYP methods lead to similar structures and energies. Both methods are suitable for hydrogen-bonded biological systems. Compared with the before mentioned methods the HCTH functional leads to longer hydrogen bonds and different relative energies for two U-quartets. Finally we calculated also structures and relative energies with the MMFF94 forcefield. Contrary to all DFT methods, MMFF94 predicts bifurcated C-H...O contacts in the uracil quartet. In the G-quartet the MMFF94 hydrogen bond distances N2-H22...N7 are shorter than the DFT distances, whereas the N1-H1...O6 distances are longer.
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  • 14
    Publication Date: 2020-11-13
    Description: Das vorliegende Skript bietet eine Einf{ü}hrung in die Graphentheorie und graphentheoretische Algorithmen. Im zweiten Kapitel werden Grundbegriffe der Graphentheorie vorgestellt. Das dritte Kapitel besch{ä}ftigt sich mit der Existenz von Wegen in Graphen. Hier wird auch die L{ö}suung des ber{ü}hmten K{ö}nigsberger Br{ü}ckenproblems aufgezeigt und der Satz von Euler bewiesen. Im vierten Kapitel wird gezeigt, wie man auf einfache Weise die Zusammenhangskomponenten eines Graphen bestimmen kann. Im Kapitel sechs wird dann sp{ä}ter mit der Tiefensuche ein Verfahren vorgestellt, das schneller arbeitet und mit dessen Hilfe man noch mehr Informationen {ü}ber die Struktur eines Graphen gewinnen kann. In den folgenden Kapiteln werden Algorithmen vorgestellt, um minimale aufspannenden B{ä}ume, k{ü}rzeste Wege und maximale Fl{ü}sse in Graphen zu bestimmen. Am Ende des Skripts wird ein kurzer Einblick in die planaren Graphen und Graphhomomorphismen geboten.
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    Language: German
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  • 15
    Publication Date: 2014-02-26
    Description: Pyridinochelin, a novel catecholate type siderophore, has been designed on the basis of the active analog enterobactin. Growth promotion tests indicate that this synthetic siderophore feeds various pathogenic bacteria effectively with iron even though it lacks one catecholate group compared to enterobactin. The superposition of the siderophore structures suggests that the structure of the skeleton connecting the catecholate groups might be an important factor for the iron transport.
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  • 16
    Publication Date: 2019-05-10
    Description: Dynamical process simulation of complex real-life problems often requires the use of modern algorithms, which automatically adapt both the time and space discretization in order to get error-controlled approximations of the solution. In this paper, a combination of linearly implicit time integrators of Rosenbrock type and adaptive multilevel finite elements based on a posteriori error estimates is presented. This approach has proven to work quite satisfactorily for a wide range of challenging practical problems. We show the performance of our adaptive method for two applications that arise in the study of flame balls and brine transport in porous media.
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  • 17
    Publication Date: 2014-02-26
    Description: The statistical behavior of deterministic and stochastic dynamical systems may be described using transfer operators, which generalize the notion of Frobenius Perron and Koopman operators. Since numerical techniques to analyze dynamical systems based on eigenvalues problems for the corresponding transfer operator have emerged, bounds on its essential spectral radius became of interest. This article shows that they are also of great theoretical interest. We give an analytical representation of the essential spectral radius in $L^{1}\!(\mu)$, which then is exploited to analyze the asymptotical properties of transfer operators by combining results from functional analysis, Markov operators and Markov chain theory. In particular, it is shown, that an essential spectral radius less than $1$, constrictiveness and some weak form'' of the so--called Doeblin condition are equivalent. Finally, we apply the results to study three main problem classes: deterministic systems, stochastically perturbed deterministic systems and stochastic systems.
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  • 18
    Publication Date: 2014-02-26
    Description: We focus on two new types of extremal graphs with respect to perfectness: critically and anticritically perfect graphs that lose their perfectness by simply deleting and adding an arbitrary edge, respectively. We present examples and study properties in order to compare critically and anticritically perfect graphs with minimally imperfect graphs, another type of extremal graphs with respect to perfectness. We discuss two attempts to characterize the classes of all critically and anticritically perfect graphs and give a brief overview on classes of perfect graphs which contain critically or anticritically perfect graphs.
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  • 19
    Publication Date: 2014-02-26
    Description: A path following algorithm for linear complementarity problems is presented. Given a point $z$ that approximates a point $z(\tau)$ on the central path with complementarity gap $\tau$, one determines a parameter $\theta\in (0,1)$ so that this point satisfies the hypothesis of the affine invariant Kantorovich Theorem for the equation defining $z((1-\theta)\tau)$. It is shown that $\theta$ is bounded below by a multiple of $n^{-1/2}$, where $n$ is the dimension of the problem. Since the hypothesis of of the Kantorovich Theorem is satisfied the sequence generated by Newton's method, or by the simplified Newton method, will converge to $z((1-\theta)\tau)$. We show that the number of steps required to obtain an acceptable approximation of $z((1-\theta)\tau)$ is bounded above by a number independent of $n$. Therefore the algorithm has $O(\sqrt{n}L)$-iteration complexity. The parameters of the algorithm can be determined in such a way that only one Newton step is needed each time the complementarity gap is decreased.
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  • 20
    Publication Date: 2014-02-26
    Description: The polynomial differential system modelling the behavior of a chemical reaction is given by graphtheoretic structures. The concepts from toric geometry are applied to study the steady states and stable steady states. Deformed toric varieties give some insight and enable graph theoretic interpretations. The importance of the circuits in the directed graph are emphazised. The counting of positive solutions of a sparse polynomial system by B.\ Sturmfels is generalized to the counting of stable positive solutions in case of a polynomial differential equation. The generalization is based on a method by sparse resultants to detect whether a system may have a Hopf bifurcation. Special examples from chemistry are used to illustrate the theoretical results.
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  • 21
    Publication Date: 2020-03-09
    Description: The increasing demand for distributed solutions in computing technology does not stop when it comes to visualization techniques. However, the capabilities of todays applications to perform remote rendering are limited by historical design legacys. Especially the popular X11 protokoll, which has been proven to be extremely flexible and usefull for remote 2D graphics applications, breaks down for the case of remote 3D rendering. In this white paper, we give a short overview of generic remote rendering technologies available today, and compare their performance to the recently released vizserver by SGI: a network extension to the SGI OpenGL rendering engines.
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  • 22
    Publication Date: 2020-08-05
    Description: This book offers a self-contained introduction to the field of semidefinite programming, its applications in combinatorial optimization, and its computational methods. We equip the reader with the basic results from linear algebra on positive semidefinite matrices and the cone spanned by them. Starting from linear programming, we introduce semidefinite programs and discuss the associated duality theory. We then turn to semidefinite relaxations of combinatorial optimization and illustrate their interrelation. In the second half we deal with computational methods for solving semidefinite programs. First, the interior point approach, its iteration complexity, and implementational issues are discussed. Next, we explain in great detail the spectral bundle method, which is particularly suited for large scale semidefinite programming. One of the most successful techniques in integer linear programming is the cutting plane approach which improves an initial relaxation by adding violated inequalities. We explore possibilities to combine the two solution methods with the cutting plane approach in order to strengthen semidefinite relaxations of combinatorial optimization problems.
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    Type: doctoralthesis , doc-type:doctoralThesis
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  • 23
    Publication Date: 2021-01-21
    Description: \\{\bf Zusammenfassung:} Kostenmodelle dienen der Ermittlung von Programmlaufzeiten, zum Vergleich der Effizienz von Algorithmen und zur Analyse des Verhaltens von Speicherhierarchien. Ein neuartiges Kostenmodell ist das Latency-of-Data-Access (LDA) Modell, das mehrere hierarchische Speicherebenen mit unterschiedlichen Latenzzeiten berü{}cksichtigt. In dieser Diplomarbeit wird ein Simulator fü{}r Speicherhierarchien prä{}sentiert, der die Berechnung von Programmausfü{}hrungszeiten nach dem LDA-Modell erlaubt. Mit Hilfe des Simulators wird die These geprü{}ft, da\ss{} mit diesem Modell die Ausfü{}hrungszeit eines Programms adä{}quat abgeschä{}tzt werden kann. Mit dem Simulator ist es erstmals praktikabel mö{}glich, Programmausfü{}hrungszeiten nach dem LDA-Modell zu bestimmen. Der Simulator kann fü{}r Systeme mit unterschiedlichen Speicherarchitekturen konfiguriert werden und unterstü{}tzt Mehrprozessorsysteme mit gemeinsamem Speicher (SMP-Systeme) mit verschiedenen Kohä{}renzprotokollen. Der Simulator kann mit den Ergebnissen von Microbenchmarks konfiguriert werden, die die Architekturparameter einer Speicherhierarchie messen. Die Ergebnisse bestä{}tigen die These nicht nur fü{}r Einzelprozessorsysteme, sondern auch fü{}r SMP-Systeme, wo gleichzeitig interagierende Prozessoren gegenseitig ihre Zugriffssequenz auf Zwischenspeicher beeinflussen. Zusä{}tzlich wurde eine neue Einsatzmö{}glichkeit des LDA-Modells entwickelt, um die Ausfü{}hrungszeit von Programmteilen zu bestimmen. Einzelne Zugriffskosten kö{}nnen einem mehrerer parallel laufender Modelle zugeordnet werden. Dadurch kö{}nnen Kosten, die Zugriffe auf einzelne Speicherbereiche verursachen, separat bestimmt werden. Diese Profiling-Technik erlaubt Optimierungen an Datenstrukturen und Speicherzugriffsmustern durch prä{}zise und gezielte Informationsproduktion.Cost models are used to determine the execution time of programs, to compare the efficiency of algorithms, and to analyse the behaviour of memory hierarchies. The Latency-of-Data-Access (LDA) model that takes into account multiple hierarchical memory levels with different latencies, is a newly proposed, innovative cost model. In this diploma-thesis, a simulator for memory hierarchies is presented that allows the calculation of execution times using the LDA-model. The simulator is used to prove the claim that the execution time of a program can be accurately estimated with the LDA-model. With the simulator, it is for the first time possible to determine the execution time of programs with this model in a practical way. The simulator can be configured for systems with various cache architectures and supports shared memory (SMP) multiprocessor systems with different cache coherence protocols. The simulator can be configured with the results from microbenchmarks which measure the architectural properties of a memory hierarchy. The results confirm the claim not only for single processor systems, but also for SMP systems, where concurrently interacting processors influence each others cache access sequence. Additionally, a new field of usage of the LDA-model was developed to determine execution times of program parts. Single access costs can be assigned to one of several parallel running models. As an example the costs of accesses to different memory areas can be split and determined separately. This profiling technique allows to optimise data structures and memory access patterns of sequential and parallel SMP programs by precise production of information.
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    Language: German
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  • 24
    Publication Date: 2014-02-26
    Description: \texttt{SBmethod}, Version 1.1, is an implementation of the spectral bundle method for eigenvalue optimization problems of the form \begin{displaymath} \min_{y\in \mathbf{R}^m}\;\; a\;\lambda_{\max}(C-\sum_{i=1}^{m} A_i y_i)+b^Ty. \end{displaymath} The design variables $y_i$ may be sign constrained, $C$ and and $A_i$ are given real symmetric matrices, $b\in\mathbf{R}^m$ allows to specify a linear cost term, and $a〉0$ is a constant multiplier for the maximum eigenvalue function $\lambda_{\max}(\cdot)$. The code is intended for large scale problems and allows to exploit structural properties of the matrices such as sparsity and low rank structure. The manual contains instructions for installation and use of the program. It describes in detail input format, options, and output. The meaning of the variables and parameters is made precise by relating them to a mathematical description of the algorithm in pseudocode.
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  • 25
    Publication Date: 2014-11-10
    Description: In this paper we introduce a generalization of stable sets: stable multi-sets. A stable multi-set is an assignment of integers to the vertices of a graph, such that specified bounds on vertices and edges are not exceeded. In case all vertex and edge bounds equal one, stable multi-sets are equivalent to stable sets. For the stable multi-set problem, we derive reduction rules and study the associated polytope. We state necessary and sufficient conditions for the extreme points of the linear relaxation to be integer. These conditions generalize the conditions for the stable set polytope. Moreover, the classes of odd cycle and clique inequalities for stable sets are generalized to stable multi-sets and conditions for them to be facet defining are determined. The study of stable multi-sets is initiated by optimization problems in the field of telecommunication networks. Stable multi-sets emerge as an important substructure in the design of optical networks.
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    Language: English
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  • 26
    Publication Date: 2020-02-11
    Description: In this paper we present the {\em SteinLib}, a library of data sets for the Steiner tree problem in graphs. This library extends former libraries on Steiner tree problems by many new interesting and difficult instances, most of them arising from real-world applications. We give a survey on the difficulty of these problem instances by giving references to state-of-the-art software packages that were the first or are currently among the best to solve these instances.
    Keywords: ddc:000
    Language: English
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  • 27
    Publication Date: 2014-02-26
    Description: Workstation clusters are often not only used for high-throughput computing in time-sharing mode but also for running complex parallel jobs in space-sharing mode. This poses several difficulties to the resource management system, which must be able to reserve computing resources for exclusive use and also to determine an optimal process mapping for a given system topology. On the basis of our CCS software, we describe the anatomy of a modern resource management system. Like Codine, Condor, and LSF, CCS provides mechanisms for the user-friendly system access and management of clusters. But unlike them, CCS is targeted at the effective support of space-sharing parallel and even metacomputers. Among other features, CCS provides a versatile resource description facility, topology-based process mapping, pluggable schedulers, and hooks to metacomputer management.
    Keywords: ddc:000
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  • 28
    facet.materialart.
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    Publication Date: 2021-02-01
    Description: Das aus den Medien bekannte umstrittene Ziegenproblem (auch Drei-Türen-Problem genannt) wird vollständig analysiert und gelöst. In der Streitfrage spielen sprachliche Mehrdeutigkeiten der Problemformulierung eine wesentliche Rolle; zudem werden Zufallsereignisse mit willkürlicher Information über deren Ergebnisse verwechselt. Tatsächlich erweisen sich beide strittigen Lösungen als teilweise richtige Bestandteile der Gesamtlösung. Die Argumentation wird in allgemeinverständlicher Sprache geführt und anschliessend durch eine formale mathematische Betrachtung ergänzt.
    Keywords: ddc:000
    Language: German
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  • 29
    Publication Date: 2020-11-13
    Description: Der Aufsatz ist die ausgearbeitete Fassung eines Vortrages, gehalten auf dem 2. BSZ-Kolloquium des Bibliotheksservice-Zentrums Baden-Württemberg (BSZ) am 10. Oktober 2000 in Konstanz. Der Kooperative Bibliotheksverbund Berlin-Brandenburg, kurz KOBV, ist ein sehr junger Verbund - genauer gesagt, befindet er sich im Oktober 2000 immer noch in der Aufbauphase. Das KOBV-Projekt hat am 1. April 1997 begonnen und wird am 31. Dezember 2000 enden. Ab 2001 wird der KOBV in eine institutionalisierte Form überführt, die - wie bereits das Projekt - am Konrad-Zuse-Zentrum für Informationstechnik Berlin (ZIB) - angesiedelt wird. Mit dem KOBV wurde ein in technischer wie auch in organisatorischer Hinsicht neuartiger Bibliotheksverbund aufgebaut, der auf der \glqq Internetphilosophie\grqq basiert: Den technischen Kern bildet eine eigens entwickelte Suchmaschine; die Organisation ist dezentral ausgerichtet und gründet sich auf der Kooperation der KOBV-Partner. In dem Vortrag werden das technische und das organisatorische Verbundkonzept vorgestellt, über die Erfahrungen nach einjähriger Betriebsdauer berichtet und ein kurzer Ausblick darüber gegeben, wie es mit dem KOBV weitergeht.
    Keywords: ddc:000
    Language: German
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  • 30
    Publication Date: 2020-11-13
    Description: Die Kommunikation zwischen der KOBV-Suchmaschine und entfernten Bibliotheksinformationssystemen unterschiedlicher Hersteller wird über das Standardprotokoll Z39.50 abgewickelt. Die Suchmaschine ermöglicht Online-Recherchen in lokalen Bibliotheksinformationssystemen, die dazu ein Z39.50 Target (Server) zur Verfügung stellen müssen. Die Suchmaschine liefert ihre Daten ebenfalls über Z39.50 aus. Ein Lokalsystem benötigt hierfür einen Z39.50 Origin (Client). In dem Papier wird die Schnittstelle zwischen der KOBV-Suchmaschine und lokalen Bibliothekssystemen spezifiziert: Es werden die grundlegenden Anforderungen an Lokalsysteme definiert und die Konfigurationsparameter für die Z39.50-Kommunikation zwischen KOBV-Suchmaschine und Lokalsystemen beschrieben.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 31
    Publication Date: 2014-02-26
    Description: Die zunehmende Verfügbarkeit von mobilen Geräten, die mit einem Internetanschluß ausgerüstet sind, bringt auch eine steigende Nachfrage nach Informationsdiensten für diese Art von Clients mit sich. Das ZIB stellt mit seinem Höchstleistungsrechner vom Typ SGI/CRAY T3E Wissenschaftlern große Rechenkapazitäten zur Verfügung. Im Rahmen dieser Studienarbeit wurde ein WAP-Interface zur T3E entwickelt, das es den Nutzern ermöglicht, über ein mobiles, WAP-fähiges Gerät Informationen zur Betriebsbereitschaft und zur Auslastung des Höchstleistungsrechners, sowie Informationen zu den von ihnen in Auftrag gegebenen Rechenjobs abzurufen. Die Untersuchung der aktuellen Möglichkeiten in der mobilen Kommunikation brachte einige Einschränkungen für das geplante Informationsangebot mit sich. So mußte auf Grund von Sicherheitsbedenken auf eine tatsächliche Interaktionsmöglichkeit (z.B. neue Rechenjobs zu starten) verzichtet werden. Demgegenüber konnte gezeigt werden, daß die Bereitstellung der gleichen Informationen für unterschiedliche Arten von Clients (WWW-Browser $\rightarrow$ HTML, WAP-Browser $\rightarrow$ WML) durch die Verwendung von XML als internes Datenformat problemlos möglich ist. Es hat sich gezeigt, daß die Bereitstellung eines WAP-Informationsdienstes auf Grund verschiedener Inkompatibilitätsprobleme (verschiedene Gateways, verschiedene WAP-Browser) mit erheblichem Aufwand verbunden sein kann. An dieser Stelle besteht noch Handlungsbedarf seitens der Hersteller dieser Softwarepakete.
    Keywords: ddc:000
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  • 32
    facet.materialart.
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    Publication Date: 2019-10-24
    Keywords: ddc:000
    Language: German
    Type: annualzib , doc-type:report
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  • 33
    Publication Date: 2014-02-26
    Description: Anwendungen der Mathematik in der Verkehrs- und Transporttechnologie haben eine große und bedeutende Tradition. Natürlich wurden die ersten Fahrzeuge mit der ingenieurmäßigen Methode von Versuch, Irrtum und Verbesserung entworfen. Aber schon sehr bald kamen mathematische Berechnungen hinzu, mit denen mechanische Eigenschaften von Fahrzeugteilen ermittelt und zum Teil optimiert wurden. Die hierzu erforderliche Mathematik wurde in diesem Jahrhundert zu einem mächtigen Werkzeugkasten ausgebaut. Mit diesem kann man heute z.B. hocheffiziente Motoren mit geringem Schadstoffausstoß entwerfen, aerodynamisch günstige Fahrzeugprofile ermitteln und Flugzeugflügel berechnen, die die gewünschte Last sicher und mit geringem Treibstoffaufwand tragen. Die Mathematik unterstützt die Technologie des Verkehrs beginnend bei globalen Designfragen bis hin zur Spezifizierung von Materialeigenschaften kleinster Bauteile; sie berechnet mit hoher Präzision energieoptimale Bahnen von Raumflugkörpern oder zeitoptimale Trajektorien für Flugzeuge, steuert automatische Roboteranlagen oder innerbetriebliche Transportsysteme.
    Keywords: ddc:000
    Language: German
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  • 34
    Publication Date: 2021-02-01
    Description: Interior point methods for multistage stochastic programs involve KKT systems with a characteristic global block structure induced by dynamic equations on the scenario tree. We generalize the recursive solution algorithm proposed in an earlier paper so that its linear complexity extends to a refined tree-sparse KKT structure. Then we analyze how the block operations can be specialized to take advantage of problem-specific sparse substructures. Savings of memory and operations for a financial engineering application are discussed in detail.
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  • 35
    Publication Date: 2014-02-26
    Description: The present paper aims at an extension of {\sc Kohonen's} Self-Organizing Map (SOM) algorithm to be called Self-Organizing Box Map (SOBM) algorithm; it generates box codebooks in lieu of point codebooks. Box codebooks just like point codebooks indirectly define a Voronoi tessellation of the input space, so that each codebook vector represents a unique set of points. Each box codebook vector comprises a multi-dimensional interval that approximates the related partition of the Voronoi tessellation. Upon using the automated cluster identification method that has recently been developed by the authors, the codebook vectors can be grouped in such a way that each group represents a point cluster in the input space. Since the clustering usually depends on the size of the SOM, one cannot be sure, whether the clustering comes out to be optimal. Refinement of part of the identified clusters would often improve the results. This paper presents the concept of an adaptive multilevel cluster algorithm that performs such refinements automatically. Moreover the paper introduces a concept of essential dimensions and suggests a method for their identification based on our herein suggested box codebooks. Applications of the algorithm to molecular dynamics will be described in a forthcoming paper.
    Keywords: ddc:000
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  • 36
    Publication Date: 2014-02-26
    Description: This paper addresses the problem of designing a minimum cost network whose capacities are sufficiently large to allow a feasible routing of a given set of multicast commodities. A multicast commodity consists of a set of two or mo re terminals that need to be connected by a so called broadcast tree, which consumes on all of its edges a capacity as large as the demand value associated with that commodity. We model the network design problem with multicast commodities as the problem of packing capacitated Steiner trees in a graph. In the first part of the paper we present three mixed-integer programming formulations for this problem. The first natural formulation uses only one integer capacity variable for each edge and and one binary tree variable for each commodity-edge pair. Applying well-known techniques from the Steiner tree problem, we then develop a stronger directed and a multicommodity flow based mixed-integer programming formulation. In the second part of the paper we study the associated polyhedra and derive valid and even facet defining inequalities for the natural formulation. Finally, we describe separation algorithms for these inequalities and present computational results that demonstrate the strength of our extended formulations.
    Keywords: ddc:000
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  • 37
    Publication Date: 2021-01-21
    Description: Kostenmodelle dienen der Ermittlung von Programmlaufzeiten, zum Vergleich der Effizienz von Algorithmen und zur Analyse des Verhaltens von Speicherhierarchien. Ein neuartiges Kostenmodell ist das Latency-of-Data-Access (LDA) Modell, das mehrere hierarchische Speicherebenen mit unterschiedlichen Latenzzeiten berücksichtigt. In dieser Diplomarbeit wird ein Simulator für Speicherhierarchien präsentiert, der die Berechnung von Programmausführungszeiten nach dem LDA-Modell erlaubt. Mit Hilfe des Simulators wird die These geprüft, daß mit diesem Modell die Ausführungszeit eines Programms adäquat abgeschätzt werden kann. Mit dem Simulator ist es erstmals praktikabel möglich, Programmausführungszeiten nach dem LDA-Modell zu bestimmen. Der Simulator kann für Systeme mit unterschiedlichen Speicherarchitekturen konfiguriert werden und unterstützt Mehrprozessorsysteme mit gemeinsamem Speicher (SMP-Systeme) mit verschiedenen Kohärenzprotokollen. Der Simulator kann mit den Ergebnissen von Microbenchmarks konfiguriert werden, die die Architekturparameter einer Speicherhierarchie messen. Die Ergebnisse bestätigen die These nicht nur für Einzelprozessorsysteme, sondern auch für SMP-Systeme, wo gleichzeitig interagierende Prozessoren gegenseitig ihre Zugriffsse-quenz auf Zwischenspeicher beeinflussen. Zusätzlich wurde eine neue Einsatzmöglichkeit des LDA-Modells entwickelt, um die Ausführungszeit von Programmteilen zu bestimmen. Einzelne Zugriffskosten können einem mehrerer parallel laufender Modelle zugeordnet werden. Dadurch können Kosten, die Zugriffe auf einzelne Speicherbereiche verursachen, separat bestimmt werden. Diese Profiling-Technik erlaubt Optimierungen an Datenstrukturen und Speicherzugriffsmustern durch präzise und gezielte Informationsproduktion.
    Description: Cost models are used to determine the execution time of programs, to compare the efficiency of algorithms, and to analyse the behaviour of memory hierarchies. The Latency-of-Data-Access (LDA) model that takes into account multiple hierarchical memory levels with different latencies, is a newly proposed, innovative cost model. In this diploma-thesis, a simulator for memory hierarchies is presented that allows the calculation of execution times using the LDA model. The simulator is used to prove the claim that the execution time of a program can be accurately estimated with the LDA model. With the simulator, it is for the first time possible to determine the execution time of programs with this model in a practical way. The simulator can be configured for systems with various cache architectures and supports shared memory (SMP) multiprocessor systems with different cache coherence protocols. The simulator can be configured with the results from Microbenchmarks which measure the architectural properties of a memory hierarchy. The results confirm the claim not only for single processor systems, but also for SMP systems, where concurrently interacting processors influence each others cache access sequence. Additionally, a new field of usage of the LDA model was developed to determine execution times of program parts. Single access costs can be assigned to one of several parallel running models. As an example the costs of accesses to different memory areas can be split and determined separately. This profiling technique allows to optimise data structures and memory access patterns of sequential and parallel SMP programs by precise production of information.
    Keywords: ddc:000
    Language: German
    Type: masterthesis , doc-type:masterThesis
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  • 38
    Publication Date: 2020-03-09
    Description: We present visualizations of recent supercomputer simulations from numerical relativity, exploiting the progress in visualization techniques and numerical methods also from an artistic point of view. The sequences have been compiled into a video tape, showing colliding black holes, orbiting and merging neutron stars as well as collapsing gravitational waves. In this paper we give some background information and provide a glance at the presented sequences.
    Keywords: ddc:000
    Language: English
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  • 39
    Publication Date: 2014-02-26
    Description: An algorithm is described to decide if a given polynomial differential expression $\Delta$ of multivariate functions is exact, i.e. whether there exists a first integral $P$ such that $D_xP = \Delta$ for any one of a set of variables $x$ and to provide the integral $P$. A generalization is given to allow integration in the case that the exactness is prohibited by terms which contain only functions of not all the independent variables.
    Keywords: ddc:000
    Language: English
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  • 40
    Publication Date: 2014-02-26
    Description: Dieser Report enthält die Ergebnisse der Untersuchungen, die gemäss dem Forschungs-- und Entwicklungsvertrag Gravity zwischen dem GeoForschungsZentrum Potsdam und dem Konrad--Zuse--Zentrum Berlin vorgenommen wurden. Die damit vereinbarte wissenschaftliche Kooperation hat die folgenden Ziele: \item{die am GFZ vorhandenen Algorithmen und Softwaremodule auf ihre Effizienz hisichtlich Nutzung der Rechnerresourcen zu untersuchen und Lösungen für einen schnelleren Datendurchsatz zu entwickeln und zu implementieren,} \item{Methoden zur Regularisierung und Lösung schlecht konditionierter Normalgleichungssysteme (für Schwerefeldkoeffizienten) kritisch zu untersuchen und eine mathematisch objektive Strategie der Regularisierung zu entwickeln, und} \item{insbesondere im Hinblick auf die Anforderungen bei GRACE, verschiedene Bahnintegrationsverfahren hinsichtlich ihrer numerischen Genauigkeit und Einsatzmöglichkeiten zu untersuchen.}
    Keywords: ddc:000
    Language: German
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  • 41
    Publication Date: 2014-02-26
    Description: We present a fully second order projection method for the simulation of two-phase incompressible flow with surface tension. The Navier-Stokes equations are solved with a projection method on a fixed Cartesian grid. The free interface between the two fluids is tracked with a level set approach. The conditions at the interface for the pressure, the pressure gradient, and the velocity are explicitly incorporated into the scheme leading to a sharp representation of the pressure discontinuity and the interfacial force. The scheme in the presented form does not introduce additional points in the standard finite difference stencils. Computational results are compared with analytic solutions for a static round bubble, damped surface waves, and Rayleigh-Taylor instabilities.
    Keywords: ddc:000
    Language: English
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  • 42
    Publication Date: 2020-03-09
    Description: HyperPlan is a software system for performing 3D-simulations and treatment planning in regional hyperthermia. It allows the user to understand the complex effects of electromagnetic wave propagation and heat transport inside a patient's body. Optimized power amplitudes and phase settings can be calculated for the BSD radiowave applicators Sigma 60 and Sigma 2000 (eye-applicator). HyperPlan is built on top of the modular, object-oriented visualization system Amira. This system already contains powerful algorithms for image processing, geometric modelling and 3D graphics display. HyperPlan provides a number of hyperthermia-specific modules, allowing the user to create 3D tetrahedral patient models suitable for treatment planning. In addition, all numerical simulation modules required for hyperthermia simulation are part of HyperPlan. This guide provides a step-by-step introduction to hyperthermia planning using HyperPlan. It also describes the usage of the underlying visualization system Amira.
    Keywords: ddc:000
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  • 43
    Publication Date: 2014-02-26
    Description: In this paper we investigate the effects of the three-dimensional arrangement of antennas and frequency on temperature distributions that can be achieved in regional hyperthermia using an electromagnetic phased array. We compare the results of power-based and temperature-based optimization. Thus we are able to explain the discrepancies between previous studies favouring more antenna rings on the one hand and more antennas per ring on the other hand. We analyze the sensitivity of the results with respect to changes in amplitudes and phases as well as patient position. This analysis can be used for different purposes. First, it provides additional criteria for selecting the optimal frequency. Second, it can be used for specifying the required phase and amplitude accuracy for a real phased array system. Furthermore, it may serve as a basis for technological developments in order to reduce both types of sensitivities described above.
    Keywords: ddc:000
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  • 44
    Publication Date: 2020-11-13
    Description: Der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) wurde in den Jahren 1997-2000 im Rahmen eines wissenschaftlichen Projektes eingerichtet. Er stellt eine neuartige Form von Bibliotheksverbund dar. Sein technisches Konzept und sein organisatorischer Aufbau basieren auf der Internetphilosophie. Den informationstechnischen Kern bildet eine Suchmaschine, die die heterogenen lokalen Bibliothekssysteme miteinander verbindet. Die KOBV-Organisation ist dezentral. Sie wird getragen von der Kooperation der Bibliotheken in Berlin und Brandenburg; diese werden von einer kleinen Verbundzentrale unterstützt. Die KOBV-Suchmaschine ist zu erreichen unter: {\begin{rawhtml}〈a href="http://www.kobv.de/suche/"〉 〈i〉 http://www.kobv.de/suche/ 〈/i〉 〈/a〉\end{rawhtml}}
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 45
    Publication Date: 2014-02-26
    Description: Dieser kurze Artikel hat keine umfassende Übersicht zum Ziel. Basierend auf eigenen Erfahrungen durch Projekte mit Industriefirmen möchte ich einige Branchen erwähnen, bei denen nach meiner Einschätzung Mathematik in Zukunft zunehmend Anwendung finden wird. Ich werde das anhand konkreter Beispiele erläutern. Mathematik ersetzt in der Regel traditionelle Analyse-, Planungs- und Entwurfstechniken. Den (nicht leichten) Schritt zum Einsatz mathematischer Methoden macht ein Praktiker nur, wenn es sich für ihn ``lohnt''. Wann sich dies lohnt, ist schwer abzuschätzen. Man kann aber einige Indikatoren dafür finden, ob eine Branche für den Einsatz von Mathematik ``reif'' ist. Ob es dann dazu kommt, hängt von vielen Faktoren ab, nicht zuletzt von der Psychologie und dem sozialen Umfeld der beteiligten Personen sowie der Bereitschaft, sich auf ein so schwieriges Terrain zu begeben und Kompromisse einzugehen. Gerade letzteres fällt Mathematikern gelegentlich schwer.
    Keywords: ddc:000
    Language: German
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  • 46
    Publication Date: 2014-11-10
    Description: All triangulations of euclidean oriented matroids are of the same PL-homeomorphism type by a result of Anderson. That means all triangulations of euclidean acyclic oriented matroids are PL-homeomorphic to PL-balls and that all triangulations of totally cyclic oriented matroids are PL-homeomorphic to PL-spheres. For non-euclidean oriented matroids this question is wide open. One key point in the proof of Anderson is the following fact: for every triangulation of a euclidean oriented matroid the adjacency graph of the set of all simplices ``intersecting'' a segment $[p_-p_+]$ is a path. We call this graph the $[p_-p_+]$-adjacency graph of the triangulation. While we cannot solve the problem of the topological type of triangulations of general oriented matroids we show in this note that for every circuit admissible triangulation of an arbitrary oriented matroid the $[p_-p_+]$-adjacency graph is a path.
    Keywords: ddc:000
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  • 47
    Publication Date: 2014-11-10
    Description: Dieser Report wurde im Sommersemester 2000 an der TU Berlin in einer Spezialvorlesung über Triangulierungen von Punktmengen und Polyedern als Skriptum verwendet. Nach einem motivierenden Kapitel werden grundlegende Begriffe und Konstruktionen in der Theorie der Triangulierungen von Punktmengen und Polyedern vorgestellt. Danach werden als weiterführende Themen reguläre Triangulierungen, Sekundärpolytope, bistellare Operationen, höhere Stasheff-Tamari-Halbordnungen und Triangulierungen mit wenigen bzw. gar keinen Flips behandelt. Ein Kapitel über Enumeration und Optimierung beschließt die Zusammenstellung.
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    Language: German
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  • 48
    Publication Date: 2020-02-11
    Description: Ende Juni diesen Jahres wurde das Gigabit-Wissenschaftsnetz offiziell gestartet. In der zweijährigen Vorbereitungsphase wurden nicht nur die technischen Möglichkeiten der neuen Übertragungstechniken und Dienste getestet. Es wurden auch verschiedene Fragestellungen zum effizienten Einsatz der verfügbaren Ressourcen für den Betrieb des G-WiN untersucht. In diesem Artikel beschreiben wir, wie das G-WiN zu seiner jetzigen Struktur und Topologie gekommen ist.
    Keywords: ddc:000
    Language: German
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  • 49
    Publication Date: 2014-02-26
    Description: We call an edge $e$ of a perfect graph $G$ critical if $G-e$ is imperfect and say further that $e$ is anticritical with respect to the complementary graph $\overline G$. We ask in which perfect graphs critical and anticritical edges occur and how to find critical and anticritical edges in perfect graphs. Finally, we study whether we can order the edges of certain perfect graphs such that deleting all the edges yields a sequence of perfect graphs ending up with a stable set.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 50
    Publication Date: 2014-02-26
    Description: We introduce a new method for reconstructing a triangular surface from an unorganized set of points in space. It is based on placing a probe sphere on the point set and rolling it around, connecting all triples of points with a triangle that the sphere comes to rest on. Therefore, the algorithm interpolates, rather than approximates, the input points. The method needs considerably less running time than previous algorithms and yields good results on point sets that are reasonably well-behaved.
    Keywords: ddc:000
    Language: English
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  • 51
    Publication Date: 2014-11-11
    Description: This paper surveys frequency assignment problems coming up in planning wireless communication services. It particularly focuses on cellular mobile phone systems such as GSM, a technology that revolutionizes communication. Traditional vertex coloring provides a conceptual framework for the mathematical modeling of many frequency planning problems. This basic form, however, needs various extensions to cover technical and organizational side constraints. Among these ramifications are $T$-coloring and list coloring. To model all the subtleties, the techniques of integer programming have proven to be very useful. The ability to produce good frequency plans in practice is essential for the quality of mobile phone networks. The present algorithmic solution methods employ variants of some of the traditional coloring heuristics as well as more sophisticated machinery from mathematical programming. This paper will also address this issue. Finally, this paper discusses several practical frequency assignment problems in detail, states the associated mathematical models, and also points to public electronic libraries of frequency assignment problems from practice. The associated graphs have up to several thousand nodes and range from rather sparse to almost complete.
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  • 52
    Publication Date: 2014-02-26
    Description: We present results on light hadron masses from simulations of full QCD and report on experiences in running such simulations on a Hitachi SR8000-F1 supercomputer.
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  • 53
    Publication Date: 2014-02-26
    Description: As has been shown recently, the identification of metastable chemical conformations leads to a Perron cluster eigenvalue problem for a reversible Markov operator. Naive discretization of this operator would suffer from combinatorial explosion. As a first remedy, a pre-identification of essential degrees of freedom out of the set of torsion angles had been applied up to now. The present paper suggests a different approach based on neural networks: its idea is to discretize the Markov operator via self-organizing (box) maps. The thus obtained box discretization then serves as a prerequisite for the subsequent Perron cluster analysis. Moreover, this approach also permits exploitation of additional structure within embedded simulations. As it turns out, the new method is fully automatic and efficient also in the treatment of biomolecules. This is exemplified by numerical results.
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  • 54
    Publication Date: 2020-11-13
    Description: In the Capacitated Dial-a-Ride Problem (CDARP) we are given a transportation network and a finite set of transportation jobs. Each job specifies the source and target location which are both part of the network. A server which can carry at most $C$~objects at a time can move on the transportation network in order to process the transportation requests. The problem CDARP consists of finding a shortest transportation for the jobs starting and ending at a designated start location. In this paper we are concerned with the restriction of CDARP to graphs which are simple paths. This setting arises for instance when modelling applications in elevator transportation systems. It is known that even for this restricted class of graphs CDARP is NP-hard to solve. We provide a polynomial time approximation algorithm that finds a transportion of length at most thrice the length of the optimal transportation.
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  • 55
    Publication Date: 2019-01-29
    Description: An affine invariant convergence analysis for inexact augmented Lagrangian-SQP methods is presented. The theory is used for the construction of an accuracy matching between iteration errors and truncation errors, which arise from the inexact linear system solves. The theoretical investigations are illustrated numerically by an optimal control problem for the Burgers equation.
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  • 56
    facet.materialart.
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    Publication Date: 2020-11-13
    Description: Wie soll man einen Aufzug steuern, wenn man keine Informationen über zukünftige Fahraufträge besitzt? Soll man eine Bahncard kaufen, wenn die nächsten Bahnreisen noch unbekannt sind? In der klassischen kombinatorischen Optimierung geht man davon aus, daß die Daten jeder Probleminstanz vollständig gegeben sind. In vielen Fällen modelliert diese \emph{Offline-Optimierung} jedoch die Situationen aus Anwendungen nur ungenügend. Zahlreiche Problemstellungen in der Praxis sind in natürlicher Weise \emph{online}: Sie erfordern Entscheidungen, die unmittelbar und ohne Wissen zukünftiger Ereignisse getroffen werden müssen. Als ein Standardmittel zur Beurteilung von Online-Algorithmen hat sich die \emph{kompetitive Analyse} durchgesetzt. Dabei vergleicht man den Zielfunktionswert einer vom Online-Algorithmus generierten Lösung mit dem Wert einer optimalen Offline-Lösung. Mit Hilfe der kompetitiven Analyse werden im Skript Algorithmen zum Caching, Netzwerk-Routing, Scheduling und zu Transportaufgaben untersucht. Auch die Schwächen der kompetitiven Analyse werden aufgezeigt und alternative Analysekonzepte vorgestellt. Neben der theoretischen Seite werden auch die Anwendungen der Online-Optimierung in der Praxis, vor allem bei Problemen der innerbetrieblichen Logistik, beleuchtet. Bei der Steuerung automatischer Transportsysteme tritt eine Fülle von Online-Problemen auf. Hierbei werden an die Algorithmen oftmals weitere Anforderungen gestellt. So müssen Entscheidungen unter strikten Zeitbeschränkungen gefällt werden (Echtzeit-Anforderungen). Dieses Skript ist aus dem Online-Teil der Vorlesung -Ausgewählte Kapitel aus der ganzzahligen Optimierung- (Wintersemester~1999/2000) und der Vorlesung -Online Optimierung- (Sommersemester~2000) an der Technischen Universität Berlin entstanden.
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    Language: German
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  • 57
    Publication Date: 2022-04-11
    Description: Wie sucht ein Wissenschaftler im Internet die ben"otigten Informationen für seine Arbeit? Welche relevanten Informationen gibt es überhaupt im Web? Sind dafür solche Suchmaschinen wie AltaVista, Google oder HotBot die richtigen Werkzeuge? Die Antwort der Mathematiker heisst Math-Net, ein Informations- und Kommunikationssystem für die Mathematik. Math-Net besteht zunächst aus den Informationen von Personen und Institutionen, die ihre für die Mathematik relevanten Informationen dort bereitstellen wollen. Das soll i.a. auf den Web-Servern der Personen oder Institutionen geschehen. Hierin unterscheidet sich die Situation im Math-Net nicht von der im WWW insgesamt. Im Math-Net sollen aber die Informationen in einheitlicher Weise erschlossen werden. Dazu gibt es sowohl für Server als auch für die Dokumente Empfehlungen für deren Strukturierung. Die lokalen Informationen werden dann im Math-Net durch automatische Verfahren gesammelt, ausgewertet und indexiert. Diese Indexe sind die Basis für die Math-Net Dienste. Das sind Search Engines und Portale, die einen qualifizierten und effizienten Zugang zu den Informationen im Math-Net bieten. Die Math-Net Dienste sind auf die Mathematik spezialisiert. Im Gegensatz zu den oben erwähnten universellen Suchmaschinen decken sie nur einen winzigen Bruchteil des Web ab, aber dafür den für die Mathematik relevanten Teil. Math-Net ist mehr als nur Search Engine oder Portal zu Informationen in der Mathematik. Es ist auch ein Informations- und Kommunikationssystem sowie ein Publikationsmedium für die Mathematik. Die mathematische Community hat sich in der Math-Net Initiative organisiert. Diese Initiative wird von der International Mathematical Union (IMU), der weltweiten Dachorganisation der mathematischen Gesellschaften, koordiniert. Die Entwicklung des Math-Net wird von dem breiten Konsens der Mathematiker getragen, den Zugang zu der für die Mathematik relevanten Information zu erleichtern und zu verbessern.
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    Language: German
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  • 58
    Publication Date: 2022-07-07
    Description: We establish the relationship between the transparent boundary condition (BPP) of Baskakov and Popov [Wave Motion 14 (1991) 121-128] and Pakpadakis et. al. [J. Acoust. Soc. Am. 92 (1992) 2030-2038] and a second boundary condition (SDY) introduced by Schmidt and Deuflhard [Comp. Math. Appl. 29 (1995) 53-76] and Schmidt and Yevick [J. Compu. Phys. 134 (1997) 96-107], that is explicitly tailored to the form of the underlying numerical propagation scheme. Our analysis demonstrates that if the domain is first discretized in the propagation direction, the SDY expression can be obtained by applying the exact sequence of steps used to derive the BPP procedure. The BPP method is thus an approximate realization of the computationally far simpler and unconditionally stable SDY boundary condition.
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  • 59
    Publication Date: 2022-07-07
    Description: We derive exact discrete nonreflecting boundary conditions for time-harmonic scattering problems modeled by the Helmholtz equation. The main idea is to consider the exterior problem as an initial value problem with initial data given on the boundary of the computational domain. The solution of the exterior problem is obtained via Laplace transformation techniques which supply the boundary conditions in terms of discrete Dirichlet-to-Neumann operators.
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  • 60
    Publication Date: 2022-07-07
    Description: This paper has been motivated by the need for a fast robust adaptive multigrid method to solve the vectorial Maxwell eigenvalue problem arising from the design of optical chips. Our nonlinear multigrid methods are based on a previous method for the scalar Helmholtz equation, which must be modified to cope with the null space of the Maxwell operator due to the divergence condition. We present two different approaches. First, we present a multigrid algorithm based on an edge element discretization of time-harmonic Maxwell's equations, including the divergence condition. Second, an explicit elimination of longitudinal magnetic components leads to a nodal discretization known to avoid discrete \emph{spurious modes} also and a vectorial eigenvalue problem, for which we present a multigrid solver. Numerical examples show that the edge element discretization clearly outperforms the nodal element approach.
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  • 61
    ISSN: 1436-3771
    Keywords: Key words Age ; Children ; Dental fluorosis ; Severity ; Tooth eruption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The purpose of this study was to investigate the influence of age on the severity of dental fluorosis in children exposed to drinking water with either low or high fluoride concentrations. The children selected for this study were aged 10–14 years, with 28 permanent teeth and at least 1 tooth pair with fluorosis. The children were permanent residents of districts in western Uganda with either 0.5 mg (n=33) or 2.5 mg fluoride/l in drinking water (n=186). All vestibular tooth surfaces were examined for fluorosis using the modified Thylstrup and Fejerskov (TF) index. In the high fluoride community, the proportion of teeth per child with TF scores ≥4, and ≥5 was significantly higher among children aged 13–14 years compared to those aged 10–12 years. Children’s chronological age correlated positively and significantly with the median TF scores for all teeth, including early erupting (first molars and incisors) and late erupting teeth (canines, premolars and second molars). In linear regression analyses, the median TF score for all teeth, as well as for early erupting and late erupting teeth, increased significantly with age. On the other hand, in the low fluoride community there was no significant association between age and the severity of fluorosis. This study showed a significant increase in the severity of fluorosis with increasing age in a high fluoride community, whereas no change in severity with age was observed in a low fluoride community.
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  • 62
    Electronic Resource
    Electronic Resource
    Springer
    The journal of headache and pain 1 (2000), S. 169-172 
    ISSN: 1129-2377
    Keywords: Key words Migraine ; Sleep ; Sleep apnea ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In our previous study we found a high prevalence of disordered sleep breathing in migraine children vs. controls. Since no quantitative studies about sleep respiratory disorders have been carried out in migraine children, we performed a polysomnographic (PSG) study in 10 migraine patients (7 boys, 3 girls; mean age 8.11 years, range, 5.8–14.5) attending the Headache Center of our department, to evaluate the presence of sleep apnea. Mothers completed a headache diary and a sleep diary for at least 1 month and filled out a sleep questionnaire. PSG data showed a normal sleep architecture in 3 cases, an insomnia pattern in 2, a reduction of slow wave sleep in 3 and a reduction of REM sleep in 2. Respiratory analysis revealed that 2 of 10 patients had obstructive sleep apnea. These 2 patients presented habitual snoring and associated sleep disturbances such as restless sleep and hypnic jerks. Sleep apnea may be a subtle and often undiagnosed symptom in several migraine patients. The report of habitual snoring associated with other sleep disturbances such as restless sleep and other parasomnias may be a sign of sleep apnea in migraine children.
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  • 63
    ISSN: 1129-2377
    Keywords: Key words Coeliac disease ; Headache ; Children ; HLA antigens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The linkage between HLA antigens and disease susceptibility has been investigated in several diseases. Two different mechanisms are known to act in the relation between the HLA system and headache: linkage and association of alleles. Among neurological disorders associated with coeliac disease (CD) we focused on headache in 1997. From a group of 70 coeliac children, we studied 10 children with headache (3 boys and 7 girls). For each subject we evaluated clinical history and HLA antigens. The incidence of headache was not different with respect to the prevalence of headache in the general population. The HLA setting is not different between the 2 groups examined. However, we highlight 2 cases for the particular HLA setting.
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  • 64
    Electronic Resource
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    Springer
    Der Nervenarzt 71 (2000), S. 164-172 
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Psychisch kranke Eltern ; Depressive Eltern ; Entwicklungsbedingungen ; Psychosoziale Bedingungen ; Kinder ; Forschungsprobleme ; Forschungsaufgaben ; Forschungskriterien ; Key words Parents with psychiatric disorders ; Depressive parents ; Developmental conditions ; Psychosocial condition ; Children ; Research problems ; Research tasks ; Research criteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Children of psychiatrically ill parents represent a risk group that has received growing attention during the last years. The risk for this group to develop a psychiatric illness is markedly increased due to genetic and psychosocial factors. The development of effective preventive concepts requires a thorough knowledge of the psychosocial factors. In this paper, deficits and problems of research in psychosocial transmission mechanisms are discussed taking the example of children of depressive parents. Conclusions from this exemplary considerations may serve as guidelines for future research. The authors suggest that the focus be rather placed on coping strategies and developmental psychopathology. Further, research criteria are formulated that refer to theoretical models as well as to study design.
    Notes: Zusammenfassung Kinder psychisch kranker Eltern stellen in psychiatrischer Hinsicht eine Risikogruppe dar, die in den letzten Jahren zunehmend in den Blickpunkt gerückt ist. Die Wahrscheinlichkeit für psychische Erkrankungen ist bei dieser Gruppe aufgrund von genetischen und psychosozialen Faktoren deutlich erhöht. Die Entwicklung von effektiven Präventionskonzepten setzt eine genaue Kenntnis der psychosozialen Faktoren voraus. In der vorliegenden Arbeit werden Defizite und Probleme bei der Erforschung der psychosozialen Transmissionsmechanismen am Beispiel der Kinder von depressiven Eltern diskutiert, und es werden Schlussfolgerungen herausgearbeitet, an denen sich die künftige Forschung orientieren sollte. Es wird vorgeschlagen, bewältigungsorientierte und entwicklungspsychopathologische Konzepte stärker zu berücksichtigen; darüber hinaus werden Forschungskriterien formuliert, die sich sowohl auf die theoretischen Modelle ebenso wie auf die Untersuchungsdesigns beziehen.
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  • 65
    Electronic Resource
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    Springer
    HNO 48 (2000), S. 828-831 
    ISSN: 1433-0458
    Keywords: Schlüsselwörter Cochlear Implant ; Resthörige Kinder ; Indikation ; Bildung ; Keywords Cochlear implant ; Children ; Indication ; Education ; Residual hearing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Background and objective. Recent indications for cochlear implant in children are bilateral total cochlear deafness and an age of 2 or more. Reports on successful implantations in adults with residual hearing pose the question of whether this indication might be expanded to children with residual hearing. Patients/Methods. In a retrospective analysis of 106 hearing-impaired children with binaural amplification, we were able to ask parents in 90 cases about their children's education. The pure-tone average of the frequencies of 1–4 kHz was correlated to education. Results. The results showed that all children except one with a pure-tone average of ≤90 dB could successfully attend regular school or kindergarten. However, those with a pure-tone average of ≥91 dB had to be educated in special units for children with impaired hearing. Conclusions. Our results indicate that amplification in children with profound hearing loss (pure-tone average ≥91 dB) is not sufficiently effective to enable them to attend regular schools or kindergarten. We conclude that the only chance to integrate these children into the world of hearing might be cochlear implantation.
    Notes: Zusammenfassung Hintergrund und Fragestellung. Die derzeit gültigen Richtlinien zur Indikation eines “Cochlear Implants” (CI) bei Kindern sind eine beidseitige cochleäre Taubheit sowie ein Lebensalter von über 2 Jahren. Berichte über die guten Hörerfolge nach Implantation von resthörigen, nicht tauben Erwachsenen werfen die Frage nach dieser Indikationserweiterung auch bei Kindern auf. Ziel unserer Arbeit war es, die Effizienz der Hörgeräteversorgung von schwerhörigen Kindern an Hand des Bildungsweges zu beurteilen um daraus Schlüsse zur Indikationserweiterung für ein CI zu ziehen. Patienten/Methodik. In einer retrospektiven Analyse von 106 beidseitig schwerhörigen, mit Hörgeräten versorgten Kindern konnte der Bildungsweg durch Befragung der Eltern in 90 Fällen erhoben werden. Ergebnisse. Durch Ermittlung der mittleren Hörschwelle in den Frequenzen 1–4 kHz und Vergleich mit dem Bildungsweg konnte gezeigt werden, dass nahezu alle Kinder (bis auf eines) mit einer Hörschwelle ≤90 dB Regelschulen oder -kindergärten mit Erfolg besuchen konnten. Alle Kinder mit einer Hörschwelle ≥91 dB mussten spezielle Einrichtungen für Hörbehinderte besuchen. Schlussfolgerungen. Da nach unseren Ergebnissen schwerhörige Kinder mit einer mittleren Hörschwelle ≥91 dB trotz Hörgeräteversorgung nicht in der Lage sind, Regelschulen oder -Kindergärten erfolgreich zu besuchen, schließen wir daraus, dass das Hauptziel einer Versorgung, nämlich der Erwerb einer ausreichenden Sprachkompetenz und -Produktion, nur durch ein CI erreicht werden kann.
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  • 66
    ISSN: 1433-0458
    Keywords: Schlüsselwörter Cochlear Implant ; Ambulante Rehabilitation ; Kinder ; Erwachsene ; Ergebnisse ; Keywords Cochlear implant ; Outpatient rehabilitation ; Cost effectiveness ; Results ; Children ; Adults
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Background and objective. This study compares the results of the outpatient-based program of the Cochlear Implant Center Ruhr with inpatient-based rehabilitation, which is almost exclusively performed in Germany. Patients/methods. The Department of Otorhinolaryngology at the University of Essen in Germany provided 52 patients with either 22- or 24-channel Nucleus cochlear implants from March 1996 to July 1999. Almost all patients (n=49) were rehabilitated on an outpatient basis, which is the standard in many cochlear implant centers outside Germany. Results. The longest follow-up period at the University of Essen Department of Otorhinolaryngology was 36 months. Minor complications occurred in 10% of the patients. After 24 months, the first three implanted patients were able to discriminate 100% of numbers and over 60% of syllables in the Freiburg speech discrimination test. The patients who developed an understanding of open speech were able to discriminate 31 words per minute with cochlear implant and without lipreading after 24 months. Children were seen to double their Schmid-Giovannini scores at 6 months postimplantation. Conclusions. The Essen outpatient-based cochlear implant program demonstrates results in speech development and speech understanding equal to those of centers providing inpatient rehabilitation. A special advantage is continuous rehabilitation with professionals known to the child for several years. In children especially, exhaustive commuting reduces school attendance and is a burden on the accompanying guardians. As an inpatient, however, the child is torn from his familiar environment. Parents with several children have particular difficulties in accompanying their child and indeed this may not always be possible.
    Notes: Zusammenfassung Hintergrund und Fragestellung. In dieser Arbeit werden die Ergebnisse der ambulanten Rehabilitation nach Cochlear-Implant-Versorgung mit denen der stationären Rehabilitation verglichen, die bisher in Deutschland fast ausschließlich durchgeführt wird. Von März 1996 bis Juli 1999 wurden an der Universitäts-Hals-Nasen-Ohren-Klinik Essen 52 taube oder an Taubheit grenzende Patienten mit einem 22-kanaligen bzw. 24-kanaligen Nucleuscochlear-Implant versorgt. Fast alle Patienten (n=49) konnten wohnortnah ambulant rehabilitiert werden, wie dies dem internationalen Standard entspricht. Ergebnisse. Der längste bisherige Nachbeobachtungszeitraum an der Universitäts-Hals-Nasen-Ohren-Klinik Essen sind 36 Monate. Nach 2 Jahren wurden von den 3 am längsten nachbeobachteten Patienten 100% der Zahlen und über 60% der Einsilber im Freiburger Sprachtest verstanden. Im “speech tracking” erreichten Patienten mit CI und ohne Lippenabsehen nach 24 Monaten 31 Wörter/min. Die Kinder zeigten 6 Monate nach Implantation eine Verdopplung des Scores im Test nach Schmid-Giovannini. Schlussfolgerungen. Das Essener Modell zeigt, dass eine ambulante Rehabilitation nach CI zu vergleichbaren Ergebnissen in der Sprachentwicklung und im Sprachverstehen führt, wie sie von anderen Zentren vorgelegt wurden, in denen fast ausschließlich stationär rehabilitiert wird. Besonders bei Kindern bedeuten lange Anfahrtswege mit einwöchigem stätionärem Aufenthalt Schulausfälle und eine Belastung für die begleitenden Eltern und Familienangehörigen zu Hause, sowie erhebliche Fahrtkosten. Stationäre Aufenthalte zur Rehabilitation reißen zudem das Kind aus seiner gewohnten Umgebung und sind für Eltern mit mehreren Kindern oft unmöglich.
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  • 67
    ISSN: 1433-0458
    Keywords: Schlüsselwörter Hörstörung ; Prävalenz ; Konnatale Hörstörungen ; Erworbene Hörstörungen ; Progredienz ; Infektionen ; Kinder ; Keywords Hearing loss ; Prevalence ; Connatal hearing loss ; Acquired hearing loss ; Progressive hearing loss ; Infections ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract The results of international investigations on connatally acquired hearing loss are compared with the data of the German Registry on Childhood Hearing Loss (4058 cases). The connatal hearing disorders have shown a notable change in the last years regarding to aetiology and prevalence. In contrast to countries of the third world in developed nations the prevalence of permanent childhood hearing loss has been reduced down to 1 in 1.000 births. The results let assume a prevalence of approximately 1:1.200 births in Germany. For instance the number of rubella embryopathia decreased effectively. In contrast CMV infections and alcohol fetopathia are playing an increasing role. In the patients of the German Registry on Childhood Hearing Loss the percentage of certainly progressive hearing loss is 10.3 within the 4058 children with permanent hearing impairment. Diagnostic procedures first of all for the early diagnosis of CMV but also of toxoplasmosis are considerable because these infections may result in treatable hearing loss. Also consequent hearing tests are demanded in children with alcohol fetopathia.
    Notes: Zusammenfassung Im vorliegenden Beitrag werden die Daten internationaler Studien zu angeborenen erworbenen Hörstörungen mit den Ergebnissen aus 4058 Fällen im Deutschen Zentralregister für kindliche Hörstörungen (DZH) verglichen und ausgewertet. Die angeborenen Erkrankungen des Hörvermögens haben innerhalb der letzten Jahre bezüglich Ätiologie und Prävalenz einen deutlichen Wandel erlebt. Im Gegensatz zu Ländern der 3. Welt ist die Prävalenz permanenter kindlicher Hörstörungen in den westlichen Industrienationen auf ca. 1:1.000 gesunken. In Deutschland liegt die Prävalenz nach ersten Ergebnissen des DZH bei ca. 1,2:1.000. So ist beispielsweise der Anteil der Rötelnembryopathien stark zurückgegangen. Dagegen spielen heute die Zytomegalievirus-(CMV)-Infektion und die Alkoholfetopathie eine größere Rolle. Im Patientenkollektiv des DZH mit 4058 permanent hörgestörten Kindern beträgt der Anteil gesichert progredienter Verläufe 10,3%. Diagnostische Verfahren, vor allem zur Früherkennung von CMV und Toxoplasmose, gewinnen zunehmend an Bedeutung. Ebenso ist eine konsequente Hördiagnostik auch bei Kindern mit Alkoholfetopathie zu fordern.
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  • 68
    ISSN: 1433-0458
    Keywords: Schlüsselwörter Cochlear Implant ; Kinder ; Eltern ; Psychische Belastung ; Erwartungshaltung ; Keywords Cochlear Implant ; Children ; Parents ; Psychosocial stress ; Expectations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Established knowledge. It is known that parents of hard-of-hearing children suffer from an increase in psychosocial stress. Scientific question. How does the psychosocial situation of parents with children who have cochlear implants change during rehabilitation? Aim of study. It was the aim of this study to demonstrate how parents evaluate retrospectively their own psychological well-being during the process of rehabilitation. Methods and results. We interviewed 87 parents by questionnaire which were mailed to them. Fifty-seven mothers and 46 fathers responded (59% return rate). Parents reported a significant increase in stress, as perceived by themselves, after the time of diagnosis. Of the parents, 25% continued to suffer from psychic stress during rehabilitation as could be demonstrated by the SCL-90-R questionnaire criteria. The expectations by parents were realistic prior to implantation but thereafter increased significantly with time. Conclusions. The psychological state of parents during the critical phase, after a diagnosis of deafness has been made for their child, has to be considered. Even after an initial phase of shock, parents seemed to be stressed to an extent that required therapeutic intervention.
    Notes: Zusammenfassung Bisheriges Wissen zum Thema. Eine generell erhöhte psychosoziale Belastung der Eltern hörbehinderter Kinder ist aus der Literatur bekannt. Wissenschaftliche Fragestellung. Wie verändert sich die psychosoziale Situation der Eltern von mit einem Cochlear Implant (CI) versorgten Kindern im zeitlichen Verlauf der Rehabilitation? Ziel der Arbeit. Ziel war es darzustellen, wie die Eltern ihr eigenes psychisches Befinden während der Rehabilitation ihres Kindes retrospektiv einschätzen. Methoden und Arbeitsergebnisse. 87 Elternpaare wurden getrennt in einer postalischen Fragebogenerhebung befragt; 57 Mütter und 46 Väter antworteten (59% Rücklauf). Die Eltern gaben ab dem Zeitpunkt der Diagnosestellung eine subjektiv deutlich erhöhte Belastung an. 25% der Eltern waren auch im weiteren Verlauf der Rehabilitation anhand der Beurteilungskriterien des SCL-90-R in einem klinisch relevanten Ausmaß psychisch belastet. Die Erwartung der Eltern vor der Implantation war realistisch und stieg im Verlauf der Rehabilitation statistisch signifikant an. Schlussfolgerungen. Die starke psychische Belastung in der Selbsteinschätzung der Eltern von CI-Kindern in der Phase der Diagnosestellung bestätigt die Theorie und klinische Praxis, dass die Eltern in dieser kritischen Phase besonderer Betreuung bedürfen. Auch über die Phase des initialen Schocks hinaus scheinen die Eltern in einem Ausmaß psychisch belastet zu sein, welches eine gezielte zusätzliche psychologische Betreuung der Eltern erforderlich machen könnte.
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  • 69
    ISSN: 1433-0474
    Keywords: Schlüsselwörter Epidemiologie ; Cholezystolithiasis ; Kinder ; Sonographie ; Risikofaktoren ; Key words Epidemiology ; Cholecystolithiasis ; Children ; Ultrasound ; Risk factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Objective. To assess the prevalence of and risk factors (e. g., obesity and positive family history) for the development of cholecystolithiasis in a non-selected collective of children and adolescents. Design and participants. A series of 482 children and adolescents aged 6–18 years underwent upper abdominal diagnostic ultrasound examinations as part of a whole-community investigation (response rate: 78%) for Echinococcus multilocularis in a town in southern Germany. Results. Gallbladder stones were identified in three of 482 children, corresponding to a prevalence of 0.6%. None of the three children was overweight at the time of the examination. Additional risk factors (pronounced weight reduction and Wilson's disease) were present in one study subject. Conclusions. Findings of the present study do not confirm the significance of obesity as a risk factor for cholecystolithiasis in children and adolescents.
    Notes: Zusammenfassung Fragestellung. Ziel der Studie war es, Häufigkeit und Risikofaktoren der Cholezystolithiasis, insbesondere Adipositas und familiäre Belastung, an einem unselektierten Kollektiv von Kindern und Jugendlichen zu untersuchen. Methode und Studienkollektiv. Ein Studienkollektiv von 482 Kindern einer Gemeinde in Süddeutschland zwischen 6 und 18 Jahren wurde in einer Vollerhebung (Responserate: 78%) im Rahmen einer Screeninguntersuchung zu Echinococcus multilocularis sonographisch untersucht. Ergebnisse. Bei 3 von 482 Kindern, entsprechend einer Prävalenz von 0,6%, wurden Gallenblasensteine festgestellt. Keines der 3 Kinder war zum Zeitpunkt der Untersuchung übergewichtig. Als weitere Risikofaktoren fanden sich bei einem Studienteilnehmer eine starke Gewichtsreduktion sowie ein M. Wilson. Schlussfolgerungen. Adipositas konnte bei Kindern und Jugendlichen in der vorliegenden Studie nicht als Risikofaktor für die Cholezystolithiasis bestätigt werden.
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  • 70
    ISSN: 1433-044X
    Keywords: Schlüsselwörter Thoraxtrauma ; Atelektasen ; Pädiatrie ; Bauchlage ; Keywords Thoracic trauma ; Atelectasis ; Children ; Prone position
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract We report on the ventilation in prone position in a 5-year-old traumatized child with severe thoracic and abdominal injuries (lung contusion, rib fractures, rupture of liver and spleen). Under continuous analgosedation, the young patient was ventilated in prone position for 6 h, since acute lung injury and atelectasis persisted despite various therapeutic measures (artifical ventilation in the pressure controlled mode, fiberoptic bronchoscopy, reexpansion maneuver). After initiation of the prone position, we observed a rapid increase i narterial oxygenation, which persisted in the following period. The hemodynamic situation remained stable. The complete disappearance of atelectasis was demonstrated radiologically after supine repositioning. After cessation of analgosedation, the extubation was performed 2 days later. Furthermore, we found no side effects of the prone position on the injured abdomen, and the liver function improved rapidly. Although there is a lack of experience with ventilation in prone position in pediatric intensive care, our report might be a recommendation for the indication of this technique in children.
    Notes: Zusammenfassung In dieser Kasuistik wird über die erfolgreiche Anwendung der Beatmung in Bauchlage bei einem 5-jährigen Mädchen berichtet, welches von einem Pkw überrollt worden war und sich Thorax- und Abdominalverletzungen (Rippenserienfraktur, Lungenkontusion, Leber- und Milzeinrisse) zugezogen hatte. Wegen des akuten Lungenversagens mit persistierenden Atelektasen, die durch wiederholte fiberoptische Bronchiallavagen und durch Reexpansionsmanöver nicht zu beheben waren, wurde der Entschluss zur 6-stündigen Lagerung auf den Bauch gefasst, obwohl über den Effekt dieser Lagerungsmaßnahme bei traumatisierten Kindern wenig bekannt ist und zu möglichen negativen Auswirkungen auf das schwerverletzte Abdomen eine Informationen vorliegen. Die Beatmung in Bauchlage führte zur raschen Verbesserung des pulmonalen Gesaustausches, die hämodynamische Situation wurde nicht beeinflusst. Die radiologische Kontrolle nach Rücklagerung zeigte eine vollständigen Rückgang der Atelektasen; die kleine Patientin konnte bald darauf extubiert werden. Weder laborchemisch noch klinisch wurde ein schädigender Einfluss auf das verletzte Abdomen gefunden. Die Beatmung in Bauchlage hat sich als Routineverfahren bei der Behandlung des Lungenversagens des Erwachsenen etabliert; nach der hier beschriebenen Erfahrung ist diese Maßnahme auch bei traumatisierten Kindern in Betracht zu ziehen, insbesondere wenn andere Maßnahmen nicht ausreichend sind.
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  • 71
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    Monatsschrift Kinderheilkunde 148 (2000), S. 113-117 
    ISSN: 1433-0474
    Keywords: Schlüsselwörter ; Kinder ; Säuglinge ; Protonenpumpenhemmer ; Omeprazol ; Pharmakologie ; Gastroösophageale Refluxkrankheit ; Ösophagitis ; Helicobacter-pylori-Infektion ; Ulkus ; Key words ; Children ; Infants ; Omeprazole ; Gastroesophageal reflux disease ; Esophagitis ; Pharmacology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Proton pump inhibitors (omeprazole, lansoprazole, and pantoprazole) have revolutionized the therapy of peptic disease of the upper gastrointestinal tract and reduced the indications for surgical intervention. These substances inhibit the H+/K+-ATPase in the parietal cells with an acid suppressing potency that is much higher than that of H2-receptor-antagonists. The first proton pump inhibitor, omeprazole, has been introduced ten years ago. Since then, sufficient experience with this drug in children has accumulated. Omeprazole is released for children aged one year or older. A new formulation makes the drug applicable in tube fed patients. The main indications for the use of omeprazole are endoscopically verified peptic esophagitis and gastric and duodenal ulcerations of different etiologies. In the treatment of Helicobacter pylori-infection a sufficient acid suppression is essential for the efficacy of the antibiotics. The recommended pediatric dose ranges between 0,7–1,4 mg/kg bodyweight and day. However, some children with ulcerative esophagitis may need daily doses up to 3.5 mg/kg. Healing of the esophageal mucosa should be monitored by endoscopy. After remission, doses can often be reduced for maintenance therapy. Side effects are rare and do not seem to increase with higher doses. Possibly interactions with other medications, i.e. antiepileptic drugs, may occur. A long-term therapy lasting more than 6 months in a child should be monitored by an experienced pediatric gastroenterologist.
    Notes: Zusammenfassung Protonenpumpeninhibitoren (Omeprazol, Lansoprazol, Pantoprazol) haben die Therapie peptischer Erkrankungen im oberen Gastrointestinaltrakt revolutioniert und die Indikation für chirurgische Therapiemaßnahmen deutlich eingeschränkt. Diese Substanzen hemmen die H+-/K+-ATPase in den Parietalzellen und haben eine sehr viel stärkere säuresuppressive Wirkung als H2-Rezeptor-Antagonisten. Mit dem ersten Vertreter dieser Substanzklasse, Omeprazol, liegen nach 10jähriger Anwendung inzwischen ausreichend Erfahrungen bei Kindern vor. Die Substanz ist für Kinder ab dem 1. Lebensjahr zugelassen und in einer neuen Darreichungsform auch bei Sondenernährung anwendbar. Die wichtigsten Indikationen für den Einsatz von Omeprazol sind eine endoskopisch gesicherte peptische Ösophagitis und Ulzerationen verschiedener Genese im Magen und Duodenum. Für eine effektive Therapie der Helicobacter-pylori-Infektion ist die ausreichende Säuresuppression essentiell für die Wirksamkeit der eingesetzten Antibiotika. Die therapeutische Dosis liegt zwischen 0,7 und 1,4 mg/kg KG und Tag, in Einzelfällen werden zur Abheilung einer Refluxösophagitis bis zu 3,5 mg/kg und Tag benötigt. Die Abheilung erosiver und ulzeröser Läsionen muß endoskopisch kontrolliert werden. Für die Erhaltungstherapie nach Abheilung sind niedrigere Dosen angemessen. Bei kurzfristiger Anwendung sind Nebenwirkungen selten und scheinen nicht dosisabhängig zu sein. Potentielle Wechselwirkungen mit anderen Medikamenten, besonders Antikonvulsiva, müssen beachtet werden. Eine Langzeittherapie bei Kindern über Monate oder Jahre muß gut überwacht werden und gehört in die Hand eines damit erfahrenen Kindergastroenterologen.
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  • 72
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    Trauma und Berufskrankheit 2 (2000), S. S136 
    ISSN: 1436-6274
    Keywords: Schlüsselwörter ; Vordere Kreuzbandverletzung ; Kinder ; Rekonstruktion ; Indikation ; Key words ; ACL lesion ; Children ; Reconstruction ; Indications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract For ACL lesions in children near to the end of the growth phase the treatment can be treated identical to that in adults. For younger children (8–12 years) the treatment must be conservative, combined with controls at short intervals. Behaviour during sport should be modified. If instability is experienced in activities of daily life or during sport a reconstruction of the ACL should be done using a central tibial transepiphyseal hamstring reconstruction with a femoral over-the-top position to avoid possible growth disturbances.
    Notes: Zusammenfassung Kreuzbandverletzungen bei Kindern, die nahe ihres Wachstumsabschlusses sind (14. bis 17. Lebensjahr) können wie Kreuzbandverletzungen von Erwachsenen behandelt werden. Kreuzbandverletzungen bei Kindern, die 13 Jahre und jünger sind, sollten zunächst abwartend behandelt werden (Kniebandage, Koordinationstraining, Belastungsreduzierung). Stellt sich im täglichen Leben oder bei sportlicher Belastung eine Instabilität im Sinne eines Giving way heraus, so sollte das Kreuzband rekonstruiert werden. Dabei ist es nach allen vorliegenden Daten unbedenklich, die Tibia zentral mit einem 8-mm-Bohrloch zu durchbohren und ein ligamentäres Transplantat durchzuziehen. Femoral ist es aus Sicherheitsgründen eher sinnvoll, statt einer transossären Bohrung die Over-the-top-Position zu wählen. Auch andere, rein epiphysäre Verankerungsmethoden (Semitendinosusplastik mit transossärer Drahtfixation) sind möglich.
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  • 73
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    Trauma und Berufskrankheit 2 (2000), S. S138 
    ISSN: 1436-6274
    Keywords: Schlüsselwörter ; Vorderes Kreuzband ; Kind ; Wachstumsfuge ; Fehlwachstum ; Key words ; Anterior cruciate ligament ; Children ; Growth plate ; Growth disturbance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Lesions of the anterior and posterior cruciate ligaments are relatively rare in childhood and adolescence; in this age group they need even more consistent and aggressive treatment than in adults as far as conservation of the menisci and definitive stabilization are concerned. Virtually no cases in which serious growth disturbance has arisen following transepiphyseal drilling are known from the literature. Thus, cruciate ligament suturing should also not be done in children, because the long-term efficacy has not been confirmed. The operative procedure is presented in detail and is related to bone age. Early transepiphyseal drilling is permissible.
    Notes: Zusammenfassung Ligamentäre Kreuzbandverletzung beim Kind und im Adoleszentenalter sind relativ selten, sie bedürfen im Vergleich zum Erwachsenen ¶einer noch konsequenteren und aggressiven Behandlung bezüglich Meniskuserhalt und definitiver Stabilisierung. In der Literatur sind praktisch keine Fälle bekannt, bei denen es tatsächlich zu einem gravierenden Fehlwachstum nach transepiphysärer Bohrung gekommen ist. Insofern sollte auch die Kreuzbandnaht beim Kind wegen der nicht bewiesenen Langzeiteffizienz unterlassen werden. Das Vorgehen im Einzelnen in Bezug zum Skelettalter wird dargestellt. Frühzeitige transepiphysäre Bohrungen sind erlaubt.
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  • 74
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    Clinical and experimental nephrology 4 (2000), S. 318-322 
    ISSN: 1437-7799
    Keywords: Key words IgA nephropathy ; Nephrotic syndrome ; Children ; Age at onset
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background. The prognostic significance of nephrotic syndrome (NS) in children with IgA nephropathy (IgAN) is unclear. Methods. NS was found in eight children with IgAN (mean onset age, 9.3 years). The clinicopathological findings of these eight children were investigated. Results. Five patients presented with macroscopic hematuria, while the remaining three were discovered in a school urinary screening program or by chance urinalysis. Six patients developed NS at the onset, and two developed NS later in the course of IgAN. All patients were treated with corticosteroids. At the end of follow-up, heavy proteinuria persisted in four children, one of whom had renal dysfunction at the onset of NS and developed end-stage renal failure, and two of whom developed NS after the onset of IgAN. Proteinuria decreased to less than 1 g/day 3 months after NS in four patients, two of whom showed disappearance of proteinuria afterward. Renal biopsy specimens revealed mesangial proliferation and crescent formation in all patients. The degree of persisting proteinuria was correlated with the presence of glomerular sclerosis, fibrous crescents, tubulo-interstitial changes on light microscopy, and depositions of C3 on immunofluorescence microscopy. Conclusions. Children who developed NS after the onset of IgAN developed renal dysfunction; the prognosis of those who showed chronic histopathological changes on renal biopsy specimens was poor, even in these young children.
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  • 75
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    Pediatric surgery international 16 (2000), S. 589-591 
    ISSN: 1437-9813
    Keywords: Key words Domestic animals ; Children ; Injury ; Evaluation ; Prevention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Domestic animals are a potential cause of serious injury to handlers and children. In developed countries dogs are the most common cause of such injuries, but in developing countries childhood injuries from domestic animals have not been given much attention. A retrospective analysis of major injuries from domestic animal attacks in children aged 12 years or less in a developing country showed 17 injuries in 16 children. The locations were the abdomen (6), head and neck (4), extremities (3), external genitalia (3), and back (1). A big-horned cow was the cause of injury in 11 patients, a donkey in 4 and a ram in 1. Children under 10 years were injured by provoked animals, mostly as bystanders, while older children were handlers. Four abdominal injuries were penetrating with evisceration and contusion of bowel and required a laparotomy. One blunt splenic injury was managed non operatively and one by partial splenectomy. Two head injuries were managed non operatively. All other injuries were examined and explored with the child under general anaesthesia. These injuries were debrided and closed primarily or closure was delayed when contamination was heavy or adequate debridement was limited by vital neighbouring structures. Broad-spectrum antibiotics and tetanus prophylaxis were given for all open wounds. The average duration of hospital stay was 7.3 days. Three patients had wound infections resulting in long hospitalizations. Two patients died (12.5%), 1 from a severe head injury and 1 from an overwhelming infection. The management of major injuries from domestic animals in children requires meticulous evaluation and examination during general anaesthesia to establish the extent of injury and avoid missed injuries. Prevention of these injuries requires public education about the proper and compassionate handling of domestic animals.
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  • 76
    ISSN: 1437-9813
    Keywords: Key words Insulinoma ; Arterial stimulation ; Calcium ; Localization ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The role of pre- and intraoperative procedures for the localization of insulinomas has been extensively debated. We report a case of successful treatment using preoperative selective intra-arterial calcium injection and intraoperative glucose monitoring. A 12-year-old boy with hypoglycemic attacks had a large insulinoma in the head of the pancreas on computed tomography. Preoperative selective angiography combined with arterial stimulation-venous sampling (ASVS) by intra-arterial injection of calcium revealed no other insulinomas in the body and tail of the pancreas. Elevation of serum glucose on intraoperative monitoring confirmed complete enucleation of the insulinoma. Preoperative ASVS can accurately localize an insulinoma, and may help to increase the success rate of surgery and avoid blind pancreatectomy.
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  • 77
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    Pediatric surgery international 16 (2000), S. 595-598 
    ISSN: 1437-9813
    Keywords: Key words Pleuropulmonary blastoma ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Pleuropulmonary blastoma (PPB) is a rare malignant neoplasm affecting children. A retrospective review was carried out of patients diagnosed as having PPB at one institute over a period of 16 years. The presentation, diagnosis, treatment, and family history were studied. PPB usually presents with symptoms and signs of respiratory tract infection, and the diagnosis may be delayed. There are no distinguishing clinical features or imaging studies. The diagnosis is made on histologic examination of tumour material and is sometimes difficult to differentiate from benign cystic lung lesions. The treatment is primarily complete excision of the tumour, followed in some cases by intense chemotherapy. PPB is a strong predictor of the presence of tumours in close relatives. Four patients treated at our institute are discussed along with a review of the literature.
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  • 78
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    Pediatric surgery international 16 (2000), S. 132-133 
    ISSN: 1437-9813
    Keywords: Key words Sigmoid volvulus ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Sigmoid volvulus is a common cause of large-bowel obstruction in elderly individuals, but is quite rare in childhood. We report six cases in patients under 20 years of age. One had Hirschprung's disease. Gangrenous sigmoid colon was found in three cases and resection was performed. Sigmoidopexy (one case) and extraperitonealization (two cases) were performed for viable sigmoid colon. There were no recurrences after 5.7 years of follow-up.
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  • 79
    ISSN: 1437-9813
    Keywords: Key words Echinococcosis ; Liver/interventional procedure ; Cyst/percutaneous drainage ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To evaluate the efficacy of ultrasound (US) guided percutaneous sclerotherapy in the pediatric population, 14 hydatid liver cysts (HLC) in eight male patients whose ages ranged between 6 and 16 years (mean 9.9 years) were treated. The maximum diameter was 110 mm. Albendazole was administered orally to all patients for 1 week before percutaneous treatment and for 3–6 months after the procedure to prevent dissemination of the disease. Cyst puncture was performed with 20 G Chiba needles using US guidance. More than one-half of the estimated cyst volume was aspirated, then 20% hypertonic saline (7 cysts) or sterile 96% alcohol (7 cysts) equivalent to one-third of the estimated cyst volume was injected into the cavity and left for 5–15 min. Finally, all the fluid in the cavity was reaspirated. Catheterization was not performed. Follow-up US examinations were performed every month during the first 6 months and every 3 months thereafter. The follow-up period ranged between 6 and 51 months (mean 15 months). No major complications were seen during or after the procedures. Two cysts in two patients completely disappeared. Volumes of the 11 cysts in five patients who were followed for 6–21 months were markedly reduced (22%–64% of the initial volume) and thick septations and solid debris-like structures were seen within the cyst cavities. There was no significant change in 1 cyst. US-guided percutaneous sclerotherapy is thus a safe and effective treatment of HLC in children.
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    Pediatric surgery international 16 (2000), S. 388-391 
    ISSN: 1437-9813
    Keywords: Key words Anorectal injury ; Children ; Diagnosis ; Morbidity ; Mortality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Anorectal injuries (ARI) are uncommon in children in civil practice. In developed countries the injuries are mainly due to sexual abuse and firearms. This report reviews the experience in tropical Africa. A retrospective study of children aged 12 years or less managed for ARI over 10 years was undertaken. There were seven children, four girls and three boys. Four injuries were due to blunt trauma and three to penetrating trauma. Six patients presented within 6 h of injury and one after 24 h. Five had rectal bleeding, which was associated with vaginal bleeding in one girl. One girl each had vaginal bleeding and vaginal discharge without rectal bleeding. Diagnosis was by rectal examination and proctoscopy. In three patients a laparotomy was necessary to exclude an intraperitoneal rectal injury (IRI); this was positive in one case. One patient with abdominal findings had a laparotomy as the primary procedure. Overall, five patients had rectal injuries (extraperitoneal 3, intraperitoneal 2), which were associated with an anal injury in three while one patient had only an anal injury. An IRI was missed at initial assessment in one girl. Associated injuries were to the vaginal wall (3), urethra (1) and head (1). IRIs were treated by repair and proximal colostomy. Extraperitoneal injuries were treated by colostomy and drainage; in two patients the injuries were accessible and were repaired. Anal and external-sphincter injuries were repaired in two cases. Vaginal lacerations were repaired and other associated injuries treated accordingly. Three patients had wound infections. Faecal continence was maintained in all patients who had anal and external-sphincter injuries. One girl died of peritonitis from a missed IRI. It is concluded that ARI remains uncommon in children. Morbidity and mortality can, however, be high. Meticulous rectal palpation and visualisation is necessary to avoid missing injuries.
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    Pediatric surgery international 16 (2000), S. 411-413 
    ISSN: 1437-9813
    Keywords: Key words Central venous catheters ; Children ; Ultrasound assessment of venous patency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To investigate the value of Doppler ultrasound scan (USS) assessment of internal jugular vein (IJV) patency after previous open central-venous cannulation (CVC), a prospective study of 66 consecutive children (median age 4.5 years; range 4 months–17 years) who had previously undergone open insertion of at least one indwelling IJV line and required further CVC for completion of therapy was undertaken. All underwent Doppler USS examination prior to surgery. Where patency of the previously cannulated vein was suggested ultrasonographically, the accuracy of this finding was confined at open surgical exploration. Initial CVCs were in situ for a median of 9 months (1 month–4 years) prior to removal. The median interval to repeated CVC was 11 months (3 weeks–45 months). In 79 Doppler USS, 70 (88.6%) veins appeared patent, 3 (4.2%) stenosed, and 6 (7.6%) obliterated. Of the 70 “USS patent” veins, 66 were explored. Patency was confirmed surgically in 59 (89.4%) and a new CVC successfully inserted. Seven (10.6%) apparently patent veins on USS were found to be obliterated at open exploration. Review of USS images in these cases suggested that enlarged collateral veins were usually responsible. Overall, successful recannulation was possible in 74.6% of all previously accessed veins. In children requiring repeated CVC, Doppler USS of neck veins is a valuable but not entirely reliable guide to the presence of underlying vessel patency and should be interpreted with caution. At least three-fourths of previously cannulated IJVs remain patent after catheter removal and can be reused for CVC.
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    Pediatric surgery international 16 (2000), S. 429-430 
    ISSN: 1437-9813
    Keywords: Key words Amebic liver abscess ; Children ; Pediatric ; Stomach ; Rupture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The occurrence of an amebic liver abscess (ALA) rupturing into the stomach is reported. ALAs in children can have atypical presentations, resulting in delayed diagnosis and increased morbidity and mortality. Timely treatment is usually followed by complete recovery.
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    Pediatric surgery international 16 (2000), S. 433-436 
    ISSN: 1437-9813
    Keywords: Key words Hernia ; Spigelian hernia ; Children ; Cryptorchidism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Congenital spigelian hernia (SH) is very rare in the pediatric age group. This is a report of two cases of SH in 1-week and 3-month-old male infants. A review of the literature revealed only 35 cases of SH in children younger than 17 years of age, bringing the total including our 2 cases to 37. There were 25 males and 12 females, a ratio of 2.1:1. Their ages ranged from 6 days to 17 years (mean 4.52 years). The hernia was situated on the right side in 13, the left side in 19, and was bilateral in 4. In one case the side of the hernia was not mentioned. In 29 cases the hernia was spontaneous while in 5 it was caused by trauma. In 3 children the hernia developed postoperatively, in 2 following repair of a congenital diaphragmatic hernia and in 1 following excision of a mediastinal neuroblastoma. Two children presented with a strangulated SH. Eleven of the 35 previously reported children had associated conditions; in 5 there was an ipsilateral undescended testis (UDT). Our two infants with SH also had an ipsilateral UDT. The significance of this association is discussed.
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    Pediatric surgery international 16 (2000), S. 454-456 
    ISSN: 1437-9813
    Keywords: Key words Priapism ; Children ; Arteries ; Fistula ; Embolisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Priapism is an uncommon problem in childhood. Most of the reported cases are in boys with sickle-cell disease or leukaemia. It occurs as a result of venous outflow obstruction, resulting in engorgement of the corpora cavernosa, and is termed “low-flow” priapism. In a small group of children priapism is due to uncontrolled arterial inflow, usually as a result of direct trauma. The authors report a case of post-traumatic arterial priapism in a child, successfully treated with selective embolisation of the internal pudendal artery. Recognition of this distinct entity is important, as it carries a good prognosis when appropriately treated.
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  • 85
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    Clinical and experimental nephrology 4 (2000), S. 225-230 
    ISSN: 1437-7799
    Keywords: Key words Peritoneal dialysis ; Dialysis index ; Urea kinetics ; Adequacy ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background. Peritoneal dialysis (PD) is an established treatment for children with end-stage renal failure. Creatinine clearance and urea kinetics are used to quantitate the dialysis treatment, but the means to assess the adequacy of dialysis in children are still controversial. Methods. We studied serum chemistry, dietary protein intake (DPI), protein catabolic rate (PCR), weekly urea clearance/body water (Kt/Vurea), weekly creatinine clearance (Ccr/week), clinical signs and symptoms during PD treatment, and peritoneal transport function in 17 children (4 to 18 years of age) with end-stage renal disease treated with PD. Fourteen children were on continuous ambulatory peritoneal dialysis (CAPD) and 3 were on automated peritoneal dialysis. Results. The mean values of the parameters tested were: blood urea nitrogen, 71 mg/dl; creatinine, 9.8 mg/dl; total protein, 6.4 g/dl; albumin, 4.0 g/dl; total Ccr, 70 l/week per 1.73 m2; DPI, 1.76 g/kg per day; PCR, 1.17 g/kg per day, and total Kt/Vurea, 2.28/week. The mean patient's clinical assessment score was 11.7, out of 15 and the mean doctor's clinical assessment score was 11.7, out of 14. The correlation between Kt/Vurea and creatinine clearance was 0.84 (P 〈 0.0001). Kt/Vurea and clinical assessment scores (patient's and doctor's scores) did not show a good correlation (r = 0.32; P = 0.228, and r = 0.47; P = 0.064, respectively). Peritoneal function seemed to be preserved after an average duration of 32 months on PD. Conclusions. These patients appeared to be fairly well dialyzed, judging from the values for the various dialysis indices obtained in this study and comparing them with adult indices.
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  • 86
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    Pediatric surgery international 16 (2000), S. 562-564 
    ISSN: 1437-9813
    Keywords: Key words Inguinal hernia ; Children ; Direct ; Recurrence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Among 109 children treated laparoscopically for inguinal hernias, 5 had direct hernias, more than would normally be anticipated. Two of the hernias were recurrences of indirect hernias operated upon previously using the open technique. Direct hernias are easier to detect with the laparoscopic technique.
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  • 87
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    Pediatric surgery international 16 (2000), S. 50-52 
    ISSN: 1437-9813
    Keywords: Key words Intestinal volvulus ; Children ; Idiopathic ; Adhesion/bands ; Resection rate ; Outcome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  In developed countries, intestinal volvulus in children is most frequently due to malrotation. To review the experience in Nigeria, a retrospective analysis of 28 patients managed over 25 years at the Ahmadu Bello University Teaching Hospital, Zaria, Nigeria, was undertaken. There were 22 boys and 6 girls with an age range of 4 days to 14 years (median 4 years). There were equal numbers over and less than 5 years of age. Vomiting (89%) and abdominal distension (79%) were the most prominent features. Thirteen children (46%) had fever, associated with bowel gangrene in 5, while 8 (29%) presented with severe dehydration and shock. A plain abdominal radiograph was the only investigation performed, but the features were not specific for volvulus. In 11 children (39%) the volvulus was idiopathic, in 9 (32%) due to adhesions or bands, in 5 (18%) to malrotation, and in 1 each a Meckel's diverticulum, internal herniation, and ventriculoperitoneal shunt. Twenty-three patients had a small-bowel, 4 sigmoid, and 1 caecal volvulus. The bowel resection rate for gangrene was 46% (small bowel 9, sigmoid 3, caecum 1). All patients with malrotation had Ladd's procedure performed. Wound infections occurred in 10 patients (36%), complete wound dehiscence in 1, and recurrence in 1 (idiopathic terminal ileal volvulus). The mortality was 21%, mostly from overwhelming infection (2 neonates, 11-year-old, 3 ≥ 5 years). Intestinal volvulus in our environment differs in aetiology from other reports. The resection rates are similar, however. This condition carries high morbidity and mortality.
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  • 88
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    Pediatric surgery international 16 (2000), S. 35-39 
    ISSN: 1437-9813
    Keywords: Key words Pancreatic trauma ; Duodenal trauma ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Diagnosis of duodenal and pancreatic injuries is frequently delayed, and optimal treatment is often controversial. Fourteen children with duodenal and/or pancreatic injuries secondary to blunt trauma were treated between 1980 and 1997. The pancreas was injured in all but 1 child. An associated duodenal injury was present in 4. The preoperative diagnosis was suspected in only 6 patients based on clinical signs and ultrasonography. One patient was treated successfully conservatively; all the others required surgical management. At operation, three procedures were used: peripancreatic drainage, suture of the gland or duodenum with drainage, and primary distal pancreatic resection without splenectomy. A duodenal resection with reconstruction by duodeno-duodenostomy was performed in 1 case. The overall complication rate was 14%: 1 fistula and 1 pseudocyst. Pancreatic ductal transection was recognized 3 days after the initial laparotomy by endoscopic retrograde cholangiopancreatography (ERCP). The mortality was 7%; 1 patient died from septic and neurologic complications. When the diagnosis of pancreatic ductal injuries is a major problem, ERCP may be a useful diagnostic procedure. Pancreatic injuries without a transected duct may often be treated conservatively. The surgical or conservative management of duodenal hematomas is still controversial; other duodenal injuries often need surgical treatment.
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  • 89
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    Archives of orthopaedic and trauma surgery 120 (2000), S. 336-337 
    ISSN: 1434-3916
    Keywords: Key words Pulled elbow ; Children ; Trauma ; Immobilization ; Nursemaid’s elbow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To evaluate the effectiveness in decreasing recurrence of cast application after manual reduction of pulled elbow. Sixty-four children with pulled elbow were randomized into two treatment groups: Group A underwent manipulative reduction followed by splinting the elbow in a flexed and supinated position for 2 days; group B underwent manipulative reduction only. Both groups were examined 2, 5, and 10 days later. None of the 33 patients in group A had a pulled elbow at follow-up. Four (13%) of 31 patients in group B had a pulled elbow 2–5 days later. Immobilizing the elbow for 2 days after manipulative reduction improves the success of treatment of a pulled elbow.
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  • 90
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    Reading and writing 13 (2000), S. 81-103 
    ISSN: 1573-0905
    Keywords: Children ; Reading comprehension ; Working memory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Education
    Notes: Abstract Working memory capacity is described as a pool of limited resources that carry out processing and storage functions. Its role has been emphasised in adults' reading comprehension. The present study had two aims: First, to study the relationship between working memory capacity and reading comprehension in fourth-grade children. Second, to study the nature of the working memory resources involved in reading comprehension, i.e., are they specific or general?To test the first point, the predictive power of working memory capacity was compared with two reading-related basic skills, vocabulary and decoding skills. To test the second point, different working memory tasks were devised using verbal, numerical and spatial materials. All the tasks were administered to 48 fourth-grade children. The results showed that working memory capacity was a direct predictor of reading comprehension when contrasted with vocabulary and decoding skills. Moreover, it seemed that working memory would be better described as a system specialised for the processing of symbolic information in that only the verbal and in a lesser extent the numerical working memory tasks were significant predictors of reading comprehension. The spatial task did not correlate with reading comprehension. The reasons accounting for the predictive power of working memory tasks were discussed.
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  • 91
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    Der Anaesthesist 49 (2000), S. 275-278 
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Tropisetron ; postoperatives Erbrechen ; Adenotonsillektomie ; Antiemetika ; Kinder ; Key words Tropisetron ; PONV ; Adenotonsillectomy ; Antiemetics ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Background: Postoperative nausea and vomiting (PONV) after tonsillectomy is a common problem in children. Tropisetron is a new 5HT3 receptor antagonist and is successfully used in paediatric patients receiving cancer therapy. The aim of the study was to assess efficacy and safety of a single intravenous dose of tropisetron for prevention of PONV in paediatric patients at risk for postoperative vomiting. Methods: In a randomised, double-blind, placebo-controlled trial, we studied 98 children aged 2–12 years undergoing tonsillectomy or adenotonsillectomy. Patients received placebo or tropisetron 0.1 mg (=0.1 ml)/kg body weight immediately after induction of anesthesia. A standard general anesthetic technique (Sevoflurane/N2O/O2 without neuromuscular blockers or opioids) was used. Perioperative vital signs, grade of sedation and episodes of postoperative nausea and vomiting were recorded. Results: No vomiting episodes occurred in 65.3% of the tropisetron treated patients compared to 34.7% of the placebo group (p=0.0024). Only 10.2% of the tropisetron treated patients vomited more than 3 times compared to 22.4% of the control patients (p=0.0004). The need for antiemetic rescue medication was significantly lower in the study group (10.4%) compared to 28.6% (p=0.025). No significant adverse effects of the study medication were shown. Conclusion: A single intravenous prophylactic dose of tropisetron effectively reduces the incidence of PONV during the first 24 postoperative hours after tonsillectomy and/or adenoidectomy. Because of the low incidence of adverse effects, the prophylactic use of tropisetron seems to be safe and justified in paediatric surgical patients at high risk for postoperative vomiting.
    Notes: Zusammenfassung Fragestellung: Erbrechen und Übelkeit nach Tonsillektomien bei Kindern sind ein häufiges Problem. Aufgrund der positiven Erfahrungen mit Tropisetron, einem neueren 5HT3 Rezeptor-Antagonisten bei Chemotherapien in der pädiatrischen Onkologie und mit anderen 5HT3 Rezeptor-Antagonisten in der Kinderchirurgie, prüften wir die Wirksamkeit und Sicherheit einer Einzeldosis Tropisetron zur Prävention von postoperativem Erbrechen bei chirurgischen Kindern mit erhöhtem Risiko für postoperatives Erbrechen. Methodik: Bei 98 Kindern im Alter von 2– 12 Jahren, die eine Tonsillektomie oder Adenotonsillektomie benötigten, führten wir eine randomisierte, doppelblinde, plazebokontrollierte Studie durch. Die Patienten erhielten Tropisetron oder Plazebo in einer Dosis von 0,1 mg (=0,1 ml)/kg KG i.v. unmittelbar nach der Narkoseeinleitung. Die Narkose erfolgte standardisiert mit Sevofluran/N2O/O2 ohne Einsatz von Opioiden und Muskelrelaxanzien. Vitalparameter, Sedationstiefe, das Auftreten von postoperativem Erbrechen und unerwünschte Wirkungen wurden aufgezeichnet. Ergebnisse: In der Tropisetrongruppe zeigten 65,3% der Kinder kein postoperatives Erbrechen, im Gegensatz zu nur 34,7% der Kinder in der Plazebogruppe (P=0,0024). Mehr als 3 Episoden von postoperativem Erbrechen zeigten nur 10,2% der Patienten in der Tropisetrongruppe im Vergleich zu 22,4% der Patienten der Kontrollgruppe (P=0,0004). Auch der Bedarf an antiemetischer Zusatzmedikation war in der Tropisetrongruppe mit 10,4% signifikant niedriger als in der Kontrollgruppe mit 28,6% (P=0,025). Bedeutsame Nebenwirkungen der Studienmedikation konnten nicht dokumentiert werden. Schlussfolgerungen: Eine prophylaktische intravenöse Einzelgabe von Tropisetron reduziert bei Kindern wirksam das Auftreten von postoperativem Erbrechen während der ersten 24 h nach einer Tonsillektomie oder Adenotonsillektomie. Die geringe Inzidenz von Nebenwirkungen rechtfertigt unserer Ansicht nach die prophylaktische Anwendung von Tropisetron bei Kindern nach Tonsillektomien.
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  • 92
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    European journal of pediatrics 159 (2000), S. 575-578 
    ISSN: 1432-1076
    Keywords: Key words Haemophilia ; HIV-negative patients ; Children ; Growth ; Body mass index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It has been shown that HIV-positive haemophilic children develop growth retardation. As not only the HIV infection but also other disease-related factors might compromise growth in these children, growth data were analysed in a longitudinal cross-sectional manner in 84 HIV-negative haemophilic patients from two university clinics. A total of 2–24 height and weight measurements (median 6) were recorded in each patient resulting in 683 single values collected between 1977–1995. Height SDS of all haemophilic boys was −0.31 ± 2.13 (mean ± SD, NS versus 0) and body mass index SDS was 0.21 ± 3.49 (mean SD, NS versus 0) at first measurement and remained unchanged throughout the observation period. Neither height nor body mass index differed with respect to the severity of haemophilia (mild/moderate/severe) or the study centre (Vienna/Prague). Conclusion Growth in HIV-negative patients with haemophilia is not affected in spite of the immunological abnormalities attributed to the substitution therapy or the bleeding episodes in the joints with the potential effect on the growth plate.
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  • 93
    ISSN: 1432-1076
    Keywords: Key words Sodium cromoglycate ; Children ; Exercise-induced asthma ; Urinary eosinophil protein X excretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This double-blind, randomised and cross-over study was designed to compare the preventive effect against exercise-induced bronchoconstriction (EIB), defined as the percentage decrease in FEV1≥15% after 6 min of exercise, of 2 mg and 10 mg of sodium cromoglycate (SCG), administered through a metered dose inhaler via spacer, in asthmatic children. Each of the 30 subject (age 11.6 ± 3.2 years) was tested on five occasions. For inclusion, EIB in test1 was required. In tests 2 to 5, all subjects inhaled 2 mg or 10 mg of SCG 20 min and 120 min before exercise in a randomised order. In order to assess excretion of eosinophil protein X (EPX) accompanying EIB, urine samples were collected before and after exercise. The mean percentage fall in FEV1 (±SD) in test 1 was 26.8 ± 9.8%. Inhalation of 2 mg and 10 mg of SCG 20 min before exercise provided a significant preventive effect in 83% and 77% and inhalation 120 min before exercise provided a preventive effect in 63% and 70%, respectively (n=30). Variance analysis did not reveal a statistically different absolute fall in FEV1 after exercise when both doses (120 min before exercise) were compared (P=0.356). In an unselected subgroup of 12 children, urinary EPX increased after the challenge without SCG premedication (test 1) (mean change: +48.7 μg/mmol creatinine, P=0.034), whereas no significant increase was found in case of SCG premedication (mean change in μg/mmol creatinine): 2 mg/20 min: +12.1; 2 mg/120 min: +8.5; 10 mg/20 min: −10.4 and 10 mg/120 min: −23.5; P 〉 0.1). Conclusion Administration of 10 mg of sodium cromoglycate is no more effective in preventing exercise-induced bronchoconstriction than 2 mg regardless of whether the medication is given 20 or 120 min before exercise. The preventive effect of sodium cromoglycate on exercise-induced bronchoconstriction in asthmatic children is associated with the inhibition of urinary eosinophil protein X excretion.
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  • 94
    ISSN: 1432-1076
    Keywords: Key words Insulin aspart ; Insulin analogue ; Type 1 diabetes ; Pharmacokinetics ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The pharmacokinetics of the novel, rapid-acting insulin aspart were compared with those of soluble human insulin following subcutaneous administration in nine children (aged 6–12 years) and nine adolescents (aged 13–17 years) with stable type 1 diabetes. The study had a randomised, double-blind, two-period crossover design. Each patient received a single subcutaneous dose of insulin aspart or human insulin (0.15 IU/kg body weight) 5 min before breakfast and the plasma insulin and glucose concentrations were measured at intervals during the following 5 h. The pharmacokinetic profile of insulin aspart differed significantly from that of human insulin with a higher mean maximum serum insulin (Cmax ins), 881 ± 321 (SD) pmol/l versus 422 ± 193 pmol/l for human insulin (P 〈 0.001); and with a shorter median serum insulin t max ins, 40.0 min (interquartile range: 40–50 min) versus 75.0 min (interquartile range: 60–120 min) for human insulin, (P 〈 0.001). An age-related effect on Cmax ins and area under the curve (AUC0–5h ins) was observed with higher values in adolescents than in children for both insulin aspart and human insulin. Postprandial glycaemic control was improved with insulin aspart; the baseline-adjusted ΔCmax glu being lower for insulin aspart compared with human insulin (increase of 7.6 ± 5.1 versus 9.4 ± 4.4 mmol/l respectively, P 〈 0.05). The incidence of adverse events was similar for the two insulin types. Conclusion The more rapid onset of action of insulin aspart versus human insulin, previously observed in adults, is confirmed in a paediatric population with type 1 diabetes.
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  • 95
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    European journal of pediatrics 159 (2000), S. 530-534 
    ISSN: 1432-1076
    Keywords: Key words Schistosomiasis ; Children ; Travellers ; Ultrasonography ; Immunodiagnosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Reports on schistosomiasis in children growing up in Europe are rare despite increased travel activity. We report on eight male and three female German children aged 50 months to 15 years with schistosomiasis. Six children were asymptomatic, whereas two presented with typical signs of Katayama fever. Persisting haematuria, headache with eosinophilia and pyelonephritis were observed in one child each. An exposure was reported for six of the children. Two were examined solely because schistosomiasis was diagnosed in a family member. All had antibodies against schistosomal antigens in at least two of three screening tests. However, schistosomal ova (Schistosoma haematobium) were detected in urine and faecal specimens from only three children. A tumour-like lesion of the bladder was found by ultrasound in only one of the children who also exhibited haematuria. Neither eosinophilia nor elevated IgE levels were constant findings. Six to 12 months after praziquantel treatment, parasitological and ultrasound checks were negative and levels of specific antibodies decreased. However, 2 years later, elevated antibody levels were detected in one girl without evidence of any new exposure. She became antibody-negative 1 year after a second course of treatment. Conclusion In contrast to residents of endemic areas, parasitological and ultrasound examinations seem to be inferior to immunodiagnostics in children from non-endemic areas at temporary risk for schistosomiasis.
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  • 96
    ISSN: 1432-1173
    Keywords: Schlüsselwörter Dermatologie ; Primary Health Care ; Langzeitergebnisse ; Kinder ; Kenia ; Keywords Dermatology ; Primary health care ; Long-term effects ; Children ; Kenya
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Background and Objective. In spite of the importance of skin diseases in Africa south of the Sahara, dermatology is insufficiently represented within the established primary health care systems. Aim of this study was to find out whether an integrated dermatology project could reduce the prevalence of dermatoses. Patients/Methods. Since 1994 trained community health workers have carried out regular weekly visits to schools and nurseries in 10 communities in rural western Kenya. Epidemiological studies were done in 13 schools in 4 communities involving 5780 and 4961 pupils one year before (1993) and 5 years (1999) following the introduction of the dermatology project. Results. Within this period the prevalence of bacterial skin infections fell from 12.7% to 11.3% (n.s.). Mycoses rose from 10.1% to 13.9% (p〈0.05), while arthropod infections (mainly scabies) remained unchanged with a prevalence of 8.3% in 1993 and 8.0% in 1999 (n.s.). Dermatitis also showed no changes (1.7% in both years). Conclusions. The prevalence of infective dermatoses depends not only on medical treatment but also far more on socio-economic factors.
    Notes: Zusammenfassung Hintergrund und Fragestellung. Trotz der großen Bedeutung der Dermatosen in Schwarzafrika ist die Dermatologie in den dort etablierten Basisgesundheitsdiensten völlig unzureichend repräsentiert. Untersucht werden sollten die Langzeitauswirkungen eines in das Primary Health Care-System integrierten Dermatologieprojekts in Bezug auf die Prävalenz von Hauterkrankungen. Patienten/Methodik. Seit 1994 besuchen ausgebildete Community Health Workers einmal wöchentlich Schulen und Vorschulkindergärten in 10 Gemeinden im ländlichen Westkenia. In 13 Schulen von 4 Gemeinden wurden 1 Jahr vor (1993) und 5 Jahre nach (1999) Projektinitiierung Reihenuntersuchungen an 5780 bzw. 4961 Kindern durchgeführt. Ergebnisse. Innerhalb dieses Zeitraums sank die Prävalenz bakteriell bedingter Dermatosen von 12,7% auf 11,3% (n.s.). Bei den Mykosen fand sich ein Anstieg von 10,1 auf 13,9% (p〈0,05). Arthropodenbedingte Infektionen (vorwiegend Skabies) blieben mit 8,3% 1993 und 8,0% 1999 (n.s.) im Wesentlichen gleich. Ekzeme wiesen zu beiden Zeitpunkten eine Prävalenz von 1,7% auf. Schlussfolgerungen. Die Prävalenz infektiöser Dermatosen hängt nur zu einem geringen Teil von der medizinischen Versorgung, sondern überwiegend von sozioökonomischen Faktoren ab.
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  • 97
    ISSN: 1432-1076
    Keywords: Key words Coeliac disease ; Children ; Iron deficiency anaemia ; Occult blood ; AbbreviationsCD coeliac disease ; ID iron deficiency ; GFD gluten-free diet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It has recently been suggested that in adults with coeliac disease, faecal blood loss may play a role in the development of iron deficiency. A group of 45 children diagnosed with coeliac disease during 1996 and 1997 were therefore prospectively evaluated for the presence of gluten in their diet, iron deficiency anaemia, and faecal occult blood. Sixty children admitted for elective surgery or asthma served as controls. Faecal occult blood was found in four iron deficient children on normal diet, of whom three were newly diagnosed. Occult blood loss disappeared in three of the four children when gluten was removed from their diet. Faecal occult blood was found in 26.7% of children on gluten-containing diet, but not in children on gluten-free diet (P=0.01), or in control children (P=0.001). Conclusion Our data suggest that the incidence of occult blood loss in coeliac disease occurs mainly in newly diagnosed cases and responds to a gluten-free diet. Occult blood testing may not be warranted in the absence of iron deficiency anaemia nor in children with iron deficiency anaemia who are on a gluten-free diet.
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  • 98
    ISSN: 1432-1173
    Keywords: Schlüsselwörter Atopisches Ekzem ; Kinder ; Elternschulung ; Video ; Mütter ; Key words Atopic eczema ; Parental education ; Video ; Children ; Mothers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Background and Objective. Psychological problems in children and parents related to children's atopic eczema (AE) may impede the success of treatment. We studied the question, if behavior-based parental education in groups (DPE) or standardized video-education (VPE) could enhance dermatological treatment effects and reduce skin-damaging behaviors in children and stress in their mothers. Patients/Methods. 47 mothers attending the university outpatient-clinic for dermatology and their AE-children (mean age 4 years) participated in the study. 18 mothers underwent the DPE (10 sessions), 15 mothers worked with VPE at home. Dermatological standard treatment (CG; N=14) served as control for a 16-weeks-evaluation-period. Results. AE-symptoms improved overall, but the effectiveness of the treatments differed significantly, improval with parent education and was best with VPE. Psychological problems of mothers were equally reduced with DPE and VPE. Conclusions. It is suggested that VPE is a cost effective and less time consuming method for supporting dermatological therapy of AE in children.
    Notes: Zusammenfassung Hintergrund und Fragestellung. Das atopische Ekzem (AE) im Kindesalter kann psychologische Probleme bei Kind und Eltern zur Folge haben, die den Behandlungserfolg erschweren. Die Effektivität direkter verhaltensorientierter Elterngruppenschulungen (DES) bzw. standardisierter Videoschulungen (VES) gegenüber der dermatologischen Standardbehandlung (KG) zur Besserung des AE, des Kratzverhaltens der Kinder und krankheitsbedingter Belastungen der Mütter wurde überprüft. Patienten/Methodik. An der Studie nahmen 47 Mütter und deren AE-Kinder (Durchschnittsalter 4 Jahre) aus der Neurodermitisambulanz der Universitätshautklinik teil, 18 Mütter besuchten die DES (10 Gruppensitzungen), 15 Mütter arbeiteten mit der VES zu Hause. Die Behandlung der KG (n=14) erfolgte im vergleichbaren 4-Monats-Zeitraum. Ergebnisse. Das AE war über alle Behandlungsbedingungen gebessert, ihre Effekstärken unterschieden sich jedoch signifikant: Elternschulungen waren effektiver als Standardbehandlung, den stärksten Effekt hatte die VES. Belastungen der Mütter reduzierten sich nach beiden Schulungsformen. Schlussfolgerungen. Die Ergebnisse verweisen auf eine Zeit und Kosten sparende Möglichkeit, Videoschulungen für die Unterstützung der Therapie des AE im Kindesalter zu nutzen.
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  • 99
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    Intensive care medicine 26 (2000), S. 942-949 
    ISSN: 1432-1238
    Keywords: Key words Ventilator-associated pneumonia ; Cardiac surgery ; Children ; Pediatric intensive care ; Complications ; Extubation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective: This study was undertaken to determine the delay of extubation attributable to ventilator-associated pneumonia (VAP) in comparison to other complications and complexity of surgery after repair of congenital heart lesions in neonates and children.¶Methods: Cohort study in a pediatric intensive care unit of a tertiary referral center. All patients who had cardiac operations during a 22-month period and who survived surgery were eligible (n = 272, median age 1.3 years). Primary outcome was time to successful extubation. Primary variable of interest was VAP. Surgical procedures were classified according to complexity. Cox proportional hazards models were calculated to adjust for confounding. Potential confounders comprised other known risk factors for delayed extubation.¶Results: Median time to extubation was 3 days. VAP occurred in 26 patients (9.6 %). The rate of VAP was not associated with complexity of surgery (P = 0.22), or cardiopulmonary bypass (P = 0.23). The adjusted analysis revealed as further factors associated with delayed extubation: other respiratory complications (n = 28, chylothorax, airway stenosis, diaphragm paresis), prolonged inotropic support (n = 48, 17.6 %), and the need for secondary surgery (n = 51, 18.8 %; e. g., re-operation, secondary closure of thorax). Older age promoted early extubation. The median delay of extubation attributable to VAP was 3.7 days (hazards ratio HR = 0.29, 95 % CI 0.18–0.49), exceeding the effect size of secondary surgery (HR = 0.48) and other respiratory complications (HR = 0.50).¶Conclusion: VAP accounts for a major delay of extubation in pediatric cardiac surgery.
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  • 100
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    Pediatric nephrology 15 (2000), S. 248-251 
    ISSN: 1432-198X
    Keywords: Key words Nephrotic syndrome ; Acute renal failure ; Children ; Peritonitis ; Ischemic tubular necrosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Idiopathic acute renal failure (IARF) is an uncommon but severe complication in children with relapsing nephrotic syndrome and may require long-term dialytic support until recovery of renal function takes place. Due to limited understanding of the pathophysiology of IARF, specific guidelines for its prevention and therapy have not been developed. Among triggering factors, peritonitis was present in half of all pediatric patients with this complication described in the English literature over the past 15 years. We report an additional nephrotic child who developed IARF following spontaneous bacterial peritonitis. The renal biopsy showed tubular epithelial changes consistent with acute tubular necrosis. A discussion of related literature and possible pathogenesis of this association is presented.
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