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  • 1995-1999  (205)
  • 1998  (205)
  • Capillary electrophoresis  (140)
  • Nuclear reactions
  • ddc:000
  • 1
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    Fast LIC with Higher Order Filter Kernels (1998)
    Details
    Publication Date: 2020-03-09
    Description: Line integral convolution (LIC) has become a well-known and popular method for visualizing vector fields. The method works by convolving a random input texture along the integral curves of the vector field. In order to accelerate image synthesis significantly, an efficient algorithm has been proposed that utilizes pixel coherence in field line direction. This algorithm, called ``fast LIC'', originally was restricted to simple box-type filter kernels. Here we describe a generalization of fast LIC for piecewise polynomial filter kernels. Expanding the filter kernels in terms of truncated power functions allows us to exploit a certain convolution theorem. The convolution integral is expressed as a linear combination of repeated integrals (or repeated sums in the discrete case). Compared to the original algorithm the additional expense for using higher order filter kernels, e.g.\ of B-spline type, is very low. Such filter kernels produce smoother, less noisier results than a box filter. This is evident from visual investigation, as well as from analysis of pixel correlations. Thus, our method represents a useful extension of the fast LIC algorithm for the creation of high-quality LIC images.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 2
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    Computer algebra algorithms and routines for the computation of conservation laws and fixing of gauge in differential expressions (1998)
    Details
    Publication Date: 2014-02-26
    Description: Three different approaches for the determination of conservation laws of differential equations are presented. For three corresponding REDUCE computer algebra programs CONLAW1/2/3 the necessary subroutines are discribed. One of them simplifies general solutions of overdetermined PDE systems so that all remaining free functions and constants correspond to independent conservation laws. It determines redundant functions and constants in differential expressions and is equally useful for the determination of symmetries or the fixing of gauge freedom in differential expressions.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 3
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    Monotone Iterations for Elliptic Variational Inequalities (1998)
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    Publication Date: 2014-02-26
    Description: A wide range of free boundary problems occurring in engineering andindustry can be rewritten as a minimization problem for astrictly convex, piecewise smooth but non--differentiable energy functional.The fast solution of related discretized problemsis a very delicate question, because usual Newton techniquescannot be applied. We propose a new approach based on convex minimization and constrained Newton type linearization. While convex minimization provides global convergence of the overall iteration, the subsequent constrained Newton type linearization is intended to accelerate the convergence speed. We present a general convergence theory and discuss several applications.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 4
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    Design of Broadband Virtual Private Networks: Model and Heuristics for the B–WiN (1998)
    Details
    Publication Date: 2014-11-11
    Description: We investigate the problem of designing survivable broadband virtual private networks that employ the Open Shortest Path First (OSPF) routing protocol to route the packages. The capacities available for the links of the network are a minimal capacity plus multiples of a unit capacity. Given the directed communication demands between all pairs of nodes, we wish to select the capacities in a such way, that even in case of a single node or a single link failure a specified percentage of each demand can be satisfied and the costs for these capacities are minimal. We present a mixed--integer linear programming formulation of this problem and several heuristics for its solution. Furthermore, we report on computational results with real-world data.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 5
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    Fourth-Order q-Difference Equation for the First Associated of the q-Classical Orthogonal Polynomials (1998)
    Details
    Publication Date: 2015-06-01
    Description: We derive the fourth order $q$-difference equation satisfied by the first associated of the $q$-classical orthogonal polynomials. The coefficients of this equation are given in terms of the polynomials $\; \sigma\;$ and $\;\tau\;$ which appear in the $q$-Pearson difference equation $\;\; D_q(\sigma\,\rho)=\tau\,\rho\;$ defining the weight $\rho$ of the $q$-classical orthogonal polynomials inside the $q$-Hahn tableau.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 6
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    The Benefits of Modularization: from KASKADE to KARDOS (1998)
    Details
    Publication Date: 2019-05-10
    Description: KARDOS solves nonlinear evolution problems in 1, 2, and 3D. An adaptive multilevel finite element algorithm is used to solve the spatial problems arising from linearly implicit discretization methods in time. Local refinement and derefinement techniques are used to handle the development of the mesh over time. The software engineering techniques used to implement the modules of the KASKADE toolbox are reviewed and their application to the extended problem class is described. A notification system and dynamic construction of records are discussed and their values for the implementation of a mesh transfer operation are shown. The need for low-level and high--level interface elements of a module is discussed for the assembling procedure of KARDOS. At the end we will summarize our experiences.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 7
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    Dynamical Systems, Numerical Integration, and Exponentially Small Estimates (1998)
    Details
    Publication Date: 2014-02-27
    Description: Dynamical systems with two well-separated time-scales are investigated using normal form theory. Exponential estimates for the normal form truncation error are derived and applied to the numerical integration of differential equations (backward error analysis) and the reduction of highly oscillatory Hamiltonian systems (constrained dynamics and correcting potentials). The theoretical results are used to formulate new algorithms for the time integration of conservative Hamiltonian systems (projected multiple time stepping, soft constraints, rigid bodies, symplectic variable step-size methods).
    Keywords: ddc:000
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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    OPUS
  • 8
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    On a Two-Queue Priority System with Impatience and its Application to a Call Center (1998)
    Details
    Publication Date: 2014-02-26
    Description: We consider a $s$-server system with two FCFS queues, where the arrival rates at the queues and the service rate may depend on the number $n$ of customers being in service or in the first queue, but the service rate is assumed to be constant for $n〉s$. The customers in the first queue are impatient. If the offered waiting time exceeds a random maximal waiting time $I$, then the customer leaves the first queue after time $I$. If $I$ is less than a given deterministic time then he leaves the system else he transits to the end of the second queue. The customers in the first queue have priority. The service of a customer from the second queue will be started if the first queue is empty and more than a given number of servers become idle. For the model being a generalization of the $M(n)/M(n)/s\!+\!GI$ system balance conditions for the density of the stationary state process are derived yielding the stability conditions and the probabilities that precisely $n$ customers are in service or in the first queue. For obtaining performance measures for the second queue a system approximation basing on fitting impatience intensities is constructed. The results are applied to the performance analysis of a call center with an integrated voice-mail-server. For an important special case a stochastic decomposition is derived illuminating the connection to the dynamics of the $M(n)/M(n)/s\!+\!GI$ system.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 9
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    On the Complexity of Vertex-Disjoint Length-Restricted Path Problems (1998)
    Details
    Publication Date: 2014-02-26
    Description: Let $G=(V,E)$ be a simple graph and $s$ and $t$ be two distinct vertices of $G$. A path in $G$ is called $\ell$-bounded for some $\ell\in\mathbb{N}$, if it does not contain more than $\ell$ edges. We study the computational complexity of approximating the optimum value for two optimization problems of finding sets of vertex-disjoint $\ell$-bounded $s,t$-paths in $G$. First, we show that computing the maximum number of vertex-disjoint $\ell$-bounded $s,t$-paths is $\mathcal{AP\kern-1pt X}$--complete for any fixed length bound $\ell\geq 5$. Second, for a given number $k\in\mathbb{N}$, $1\leq k \leq |V|-1$, and non-negative weights on the edges of $G$, the problem of finding $k$ vertex-disjoint $\ell$-bounded $s,t$-paths with minimal total weight is proven to be $\mathcal{NPO}$--complete for any length bound $\ell\geq 5$. Furthermore, we show that, even if $G$ is complete, it is $\mathcal{NP}$--complete to approximate the optimal solution value of this problem within a factor of $2^{\langle\phi\rangle^\epsilon}$ for any constant $0〈\epsilon〈1$, where $\langle\phi\rangle$ denotes the encoding size of the given problem instance $\phi$. We prove that these results are tight in the sense that for lengths $\ell\leq 4$ both problems are polynomially solvable, assuming that the weights satisfy a generalized triangle inequality in the weighted problem. All results presented also hold for directed and non-simple graphs. For the analogous problems where the path length restriction is replaced by the condition that all paths must have length equal to $\ell$ or where vertex-disjointness is replaced by edge-disjointness we obtain similar results.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 10
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    Order Picking in an Automatic Warehouse: Solving Online Asymmetric TSPs (1998)
    Details
    Publication Date: 2014-02-26
    Description: We report on a joint project with industry that had the aim to sequence transportation requests within an automatic storage system in such a way that the overall travel time is minimized. The manufacturing environment is such that scheduling decisions have to be made before all jobs are known. We have modeled this task as an \emph{online} Asymmetric Traveling Salesman Problem (ATSP). Several heuristics for the online ATSP are compared computationally within a simulation environment to judge which should be used in practice. Compared to the priority rule used so far, the optimization package reduced the unloaded travel time by about 40~\%. Because of these significant savings our procedure was implemented as part of the control software for the stacker cranes of the storage systems.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 11
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    A Two-Stage Stochastic Program for Unit Commitment Under Uncertainty in a Hydro-Thermal Power System (1998)
    Details
    Publication Date: 2014-02-26
    Description: We develop a two-stage stochastic programming model with integer first-stage and mixed-integer recourse for solving the unit commitment problem in power generation in the presence of uncertainty of load profiles. The solution methodology rests on a novel scenario decomposition method for stochastic integer programming. This method combines Lagrangian relaxation of non-anticipativity constraints with branch-and-bound. It can be seen as a decomposition algorithm for large-scale mixed-integer linear programs with block-angular structure. With realistic data from a German utility we validate our model and carry out test runs. Sizes of these problems go up to 20.000 integer and 150.000 continuous variables together with up to 180.000 constraints.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 12
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    The Generalized Baues Problem for Cyclic Polytopes I. (1998)
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    Publication Date: 2014-11-10
    Description: The Generalized Baues Problem asks whether for a given point configuration the order complex of all its proper polyhedral subdivisions, partially ordered by refinement, is homotopy equivalent to a sphere. In this paper, an affirmative answer is given for the vertex sets of cyclic polytopes in all dimensions. This yields the first non-trivial class of point configurations with neither a bound on the dimension, the codimension, nor the number of vertice for which this is known to be true. Moreover, it is shown that all triangulations of cyclic polytopes are lifting triangulations. This contrasts the fact that in general there are many non-regular triangulations of cyclic polytopes. Beyond this, we find triangulations of $C(11,5)$ with flip deficiency. This proves---among other things---that there are triangulations of cyclic polytopes that are non-regular for every choice of points on the moment curve.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 13
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    Explicit Variable Step-Size and Time-Reversible Integration (1998)
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    Publication Date: 2014-02-26
    Description: A variable step-size, semi-explicit variant of the explicit Störmer-Verlet method has been proposed for the time-reversible integration of Newton's equations of motion by Huang & Leimkuhler. Here we propose a fully explicit version of this approach applicable to explicit and symmetric integration methods for general time-reversible differential equations. As applications, we discuss the variable step-size, time-reversible, and fully explicit integration of rigid body motion and reversible Nos\'e-Hoover dynamics.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 14
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    Adaptive Multilevel FEM as Decisive Tools in the Clinical Cancer Therapy Hyperthermia (1998)
    Details
    Publication Date: 2014-02-26
    Description: The paper surveys recent progress in a joint mathematical-medical project on cancer therapy planning. Within so-called regional hyperthermia the computational task is to tune a set of coupled radiofrequency antennas such that a carefully measured tumor is locally heated, but any outside hot spots are avoided. A mathematical model of the whole clinical system -- air, applicator with antennas, water bolus, individual patient body -- involves Maxwell's equations in inhomogeneous media and a parabolic bioheat transfer equation, which represents a simplified model of heat transfer in the human body (ignoring strong blood vessel heat transport). Both PDEs need to be computed fast and to medical reliability (!) on a workstation within a clinical environment. This requirement triggered a series of new algorithmic developments to be reported here, among which is an adaptive multilevel FEM for Maxwell's equations, which dominates the numerical simulation time. In total, however, the main bulk of computation time (see Table 3 in Section 4 below) still goes into segmentation -- a necessary preprocessing step in the construction a 3D virtual patient from the input of a stack of 2D computed tomograms (left out here).
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 15
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    Extension of finite volume compressible flow solvers to multi-dimensional, variable density zero Mach number flow (1998)
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    Publication Date: 2014-02-26
    Description: When attempting to compute unsteady, variable density flows at very small or zero Mach number using a standard finite volume compressible flow solver one faces at least the following difficulties: (i) Spatial pressure variations vanish as the Mach number $M \rightarrow 0$, but they do affect the velocity field at leading order; (ii) the resulting spatial homogeneity of the leading order pressure implies an elliptic divergence constraint for the energy flux; (iii) violation of this constraint would crucially affect the transport of mass, thereby disabling a code to properly advect even a constant density distribution. A previous companion paper derived the above observations from a single time - multiple length scale asymptotic analysis for $M \ll 1$, applied to the conservation form of the governing equations and assuming an ideal gas with constant specific heats. The paper then restricted to weakly compressible one-dimensional flows and introduced a semi-implicit extension of a compressible flow solver, designed to handle the interaction of long wavelength acoustics with small scale, large amplitude density fluctuations. In the present paper we concentrate on the limit of zero Mach number for multi-dimensional, variable density flows. The construction of numerical fluxes for all conserved quantities involves: An explicit upwind step (1) yielding predictions for the nonlinear convective flux components. This procedure still neglects the influence of pressure gradients on the convective fluxes during the time step. Suitable corrections are applied in step (2), which guarantees compliance of the convective fluxes with the divergence constraint. This step requires the solution of a Poisson-type equation to obtain the relevant pressure gradients. Step (3), which requires the solution of a second Poisson-type equation, yields the yet unknown (non-convective) pressure contribution to the total flux of momentum. The final, cell centered velocity field exactly satisfies a discrete divergence constraint consistent with the asymptotic limit. Notice that step (1) can be done by any standard finite volume compressible flow solver and that the input to steps (2) and (3) involves solely the fluxes from step (1), but is independent on how these were obtained. Thus, we claim that our approach allows any such solver to be extended to simulate incompressible flows. Extensions to the weakly compressible regime $0 〈 M \ll 1$, reactive flows and more complex equations of state will be addressed in follow-up publications.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 16
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    A New Nonlinear Elliptic Multilevel FEM Applied to Regional Hyperthermia (1998)
    Details
    Publication Date: 2019-01-29
    Description: In the clinical cancer therapy of regional hyperthermia nonlinear perfusion effects inside and outside the tumor seem to play a not negligible role. A stationary model of such effects leads to a nonlinear Helmholtz term within an elliptic boundary value problem. The present paper reports about the application of a recently designed adaptive multilevel FEM to this problem. For several 3D virtual patients, nonlinear versus linear model is studied. Moreover, the numerical efficiency of the new algorithm is compared with a former application of an adaptive FEM to the corresponding instationary model PDE.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 17
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    Combinatorial Online Optimization (1998)
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    Publication Date: 2020-11-13
    Description: In ``classical'' optimization, all data of a problem instance are considered given. The standard theory and the usual algorithmic techniques apply to such cases only. Online optimization is different. Many decisions have to be made before all data are available. In addition, decisions once made cannot be changed. How should one act ``best'' in such an environment? In this paper we survey online problems coming up in combinatorial optimization. We first outline theoretical concepts, such as competitiveness against various adversaries, to analyze online problems and algorithms. The focus, however, lies on real-world applications. We report, in particular, on theoretical investigations and our practical experience with problems arising in transportation and the automatic handling of material.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 18
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    Recursive Direct Optimization and Successive Refinement in Multistage Stochastic Programs (1998)
    Details
    Publication Date: 2021-02-01
    Description: The paper presents a new algorithmic approach for multistage stochastic programs which are seen as discrete optimal control problems with a characteristic dynamic structure induced by the scenario tree. To exploit that structure, we propose a highly efficient dynamic programming recursion for the computationally intensive task of KKT systems solution within a primal-dual interior point method. Convergence is drastically enhanced by a successive refinement technique providing both primal and dual initial estimates. Test runs on a multistage portfolio selection problem demonstrate the performance of the method.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 19
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    Scientific Information Systems and Metadata (1998)
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    Publication Date: 2014-02-26
    Description: This article begins with a short survey on the history of the classification of knowledge. It briefly discusses the traditional means of keeping track of scientific progress, i.e., collecting, classifying, abstracting, and reviewing all publications in a field. The focus of the article, however, is on modern electronic information and communication systems that try to provide high-quality information by automatic document retrieval or by using metadata, a new tool to guide search engines. We report, in particular, on efforts of this type made jointly by a number of German scientific societies. A full version of this paper including all hypertext references, links to online papers and references to the literature can be found under the URL: {\tt http://elib.zib.de/math.org.softinf.pub} .
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 20
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    Fast Data Assimilation in Fire Tests of Steel Members (1998)
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    Publication Date: 2020-03-11
    Description: This report presents a fast data assimilation method to produce an interpolating time and space temperature distribution for steel members subject to fire testing. The method assimilates collected temperature data into the numerical integration of the heat equation. This physically based method also allows the computation of lateral and axial heat flux into and inside the member.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 21
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    The Online Transportation Problem: Competitive Scheduling of Elevators (1998)
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    Publication Date: 2020-11-13
    Description: In this paper we consider the following online transportation problem (\textsc{Oltp}): Objects are to be transported between the vertices of a given graph. Transportation requests arrive online, specifying the objects to be transported and the corresponding source and target vertex. These requests are to be handled by a server which commences its work at a designated origin vertex and which picks up and drops objects at their starts and destinations. After the end of its service the server returns to its start. The goal of \textsc{Oltp} is to come up with a transportation schedule for the server which finishes as early as possible. We first show a lower bound of~$5/3$ for the competitive ratio of any deterministic algorithm. We then analyze two simple and natural strategies which we call \textsf{REPLAN} and \textsf{IGNORE}. \textsf{REPLAN} completely discards its schedule and recomputes a new one when a new request arrives. \textsf{IGNORE} always runs a (locally optimal) schedule for a set of known requests and ignores all new requests until this schedule is completed. We show that both strategies, \textsf{REPLAN} and \textsf{IGNORE}, are $5/2$-competitive. We also present a somewhat less natural strategy \textsf{SLEEP}, which in contrast to the other two strategies may leave the server idle from time to time although unserved requests are known. We also establish a competitive ratio of~$5/2$ for the algorithm \textsf{SLEEP}. Our results are extended to the case of ``open schedules'' where the server is not required to return to its start position at the end of its service.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 22
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    From Simulation Data to Conformational Ensembles: Structure and Dynamics based Methods (1998)
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    Publication Date: 2014-02-26
    Description: Statistical methods for analyzing large data sets of molecular configurations within the chemical concept of molecular conformations are described. The strategies are based on dependencies between configurations of a molecular ensemble; the article concentrates on dependencies induces by a) correlations between the molecular degrees of freedom, b) geometrical similarities of configurations, and c) dynamical relations between subsets of configurations. The statistical technique realizing aspect a) is based on an approach suggested by {\sc Amadei et al.} (Proteins, 17 (1993)). It allows to identify essential degrees of freedom of a molecular system and is extended in order to determine single configurations as representatives for the crucial features related to these essential degrees of freedom. Aspects b) and c) are based on statistical cluster methods. They lead to a decomposition of the available simulation data into {\em conformational ensembles} or {\em subsets} with the property that all configurations in one of these subsets share a common chemical property. In contrast to the restriction to single representative conformations, conformational ensembles include information about, e.g., structural flexibility or dynamical connectivity. The conceptual similarities and differences of the three approaches are discussed in detail and are illustrated by application to simulation data originating from a hybrid Monte Carlo sampling of a triribonucleotide.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 23
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    Weighted Labels for 3D Image Segmentation (1998)
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    Publication Date: 2020-03-09
    Description: Segmentation tools in medical imaging are either based on editing geometric curves or on the assignment of region labels to image voxels. While the first approach is well suited to describe smooth contours at subvoxel accuracy, the second approach is conceptually more simple and guarantees a unique classification of image areas. However, contours extracted from labeled images typically exhibit strong staircase artifacts and are not well suited to represent smooth tissue boundaries. In this paper we describe how this drawback can be circumvented by supplementing region labels with additional weights. We integrated our approach into an interactive segmentation system providing a well-defined set of manual and semi-automatic editing tools. All tools update both region labels as well as the corresponding weights simultaneously, thus allowing one to define segmentation results at high resolution. We applied our techniques to generate 3D polygonal models of anatomical structures.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    OPUS
  • 24
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    Zielorientierte Dienstplanoptimierung (1998)
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    Publication Date: 2020-03-09
    Description: Dieser Artikel behandelt einen Ansatz zur zielorientierten Optimierung der Dienstplanung im ÖPNV. Der Ansatz zielt auf die vollständige Ausnutzung aller planerischen Freiheitsgrade unter korrekter Berücksichtigung von gesetzlichen, tariflichen, technischen und betrieblichen Rahmenbedingungen. Er basiert auf mathematischen Optimierungstechniken, die wir gegenwärtig in einem vom Bundesministerium für Bildung und Forschung ({\tt bmb+f}) geförderten Verbundprojekt in einer Kooperation zwischen der HanseCom GmbH, der IVU GmbH und dem Konrad-Zuse-Zentrum für Informationstechnik Berlin entwickeln. Es ist geplant, das Verfahren in die Softwareprodukte HOT II, MICROBUS II und OPUS zu integrieren. Verhandlungen mit den Berliner Verkehrsbetrieben über eine Projektbeteiligung und Integration unserer Software in BERTA sind zur Zeit im Gang. Wir beschreiben die Methodik des Ansatzes, diskutieren Aspekte seiner praktischen Verwendung, und wir berichten über den Stand der Entwicklung.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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    OPUS
  • 25
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    Visualizing conformations in molecular dynamics (1998)
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    Publication Date: 2020-03-09
    Description: The Monte Carlo simulation of the dynamics of complex molecules produces trajectories with a large number of different configurations to sample configuration space. It is expected that these configurations can be classified into a small number of conformations representing essential changes in the shape of the molecule. We present a method to visualize these conformations by point sets in the plane based on a geometrical distance measure between individual configurations. It turns out that different conformations appear as well-separated point sets. The method is further improved by performing a cluster analysis of the data set. The point-cluster representation is used to control a three-dimensional molecule viewer application to show individual configurations and conformational changes. The extraction of essential coordinates and visualization of molecular shape is discussed.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 26
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    Kooperativer Bibliotheksverbund Berlin-Brandenburg - Schnittstelle Lokalsysteme-Suchmaschine, Spezifikation der Anforderungen (1998)
    Details
    Publication Date: 2020-11-13
    Description: Die Kommunikation zwischen der Suchmaschine und den Lokalsystemen findet über eine offene Schnittstelle statt. Als Standardschnittstelle dient Z39.50-1995 (auch als Z39.50, Level 3 bekannt). Grundsätzlich können auch Lokalsysteme angesprochen werden, die nur über eine WWW-Schnittstelle verfügen. Dieses Papier spezifiziert die Anforderungen, die seitens der KOBV-Suchmaschine an ein Lokalsystem gestellt werden.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 27
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    Kooperativer Bibliotheksverbund Berlin-Brandenburg - Normdaten im KOBV (1998)
    Details
    Publication Date: 2020-11-13
    Description: Der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) wird sich aktiv am Aufbau der deutschen Normdateien Gemeinsame Körperschaftsdatei (GKD), Schlagwortnormdatei (SWD) und Personennamendatei (PND) beteiligen, die in Gemeinschaftsarbeit der deutschen Bibliotheksverbünde erstellt werden. Nach der Konzeption liegen die Normdateien auf dem zentralen KOBV-Server auf und stehen über die Suchmaschine allen angeschlossenen Bibliotheken zur Verfügung. Lokal befinden sich nur die Normdatensätze, die mit Titeln verknüpft sind. Das Update der Normdaten geschieht zentral. Es werden Lösungen aufgezeigt, wie die Normdaten von den KOBV-Bibliotheken mittels offener Schnittstellen (Z39.50) genutzt und erstellt werden können und auf welche Weise der KOBV mit den Redaktionen der Normdateien zusammenarbeiten kann. Neben den technischen werden auch die organisatorischen Fragen erörtert, die mit dem neuartigen KOBV-Konzept der dezentralen Nutzung der Normdaten in den lokalen Bibliothekssystemen zusammenhängen. Weitere Themen sind die regionale Zusammenarbeit der Bibliotheken und der KOBV-Zentrale mit der Zeitschriftendatenbank (ZDB) sowie die Einbindung zusätzlicher Normdaten, wie Universal- bzw. Fachklassifikationen und Thesauri.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 28
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    iTe 1.1 User's Guide (1998)
    Details
    Publication Date: 2014-02-26
    Description: iTe is an easy to use, interactive authoring tool for LaTeX and TeX documents. With iTe, it is possible to select arbitrary display fragments such as figures, equations, labels, captions, etc. These fragments can then be freely moved, rotated and scaled.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 29
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    Optimization of Transportation Systems (1998)
    Details
    Publication Date: 2020-03-09
    Description: The world has experienced two hundred years of unprecedented advances in vehicle technology, transport system development, and traffic network extension. Technical progress continues but seems to have reached some limits. Congestion, pollution, and increasing costs have created, in some parts of the world, a climate of hostility against transportation technology. Mobility, however, is still increasing. What can be done? There is no panacea. Interdisciplinary cooperation is necessary, and we are going to argue in this paper that {\em Mathematics\/} can contribute significantly to the solution of some of the problems. We propose to employ methods developed in the {\em Theory of Optimization\/} to make better use of resources and existing technology. One way of optimization is better planning. We will point out that {\em Discrete Mathematics\/} provides a suitable framework for planning decisions within transportation systems. The mathematical approach leads to a better understanding of problems. Precise and quantitative models, and advanced mathematical tools allow for provable and reproducible conclusions. Modern computing equipment is suited to put such methods into practice. At present, mathematical methods contribute, in particular, to the solution of various problems of {\em operational planning}. We report about encouraging {\em results\/} achieved so far.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
    Format: application/postscript
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  • 30
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    On crepant resolutions of 2-parameter series of Gorenstein cyclic quotient singularities (1998)
    Details
    Publication Date: 2020-09-25
    Description: \noindent An immediate generalization of the classical McKay correspondence for Gorenstein quotient spaces $\Bbb{C}^{r}/G$ in dimensions $r\geq 4$ would primarily demand the existence of projective, crepant, full desingularizations. Since this is not always possible, it is natural to ask about special classes of such quotient spaces which would satisfy the above property. In this paper we give explicit necessary and sufficient conditions under which 2-parameter series of Gorenstein cyclic quotient singularities have torus-equivariant resolutions of this specific sort in all dimensions.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 31
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    Adaptive Incompressible Flow Computations with Linearly Implicit Time Discretization and Stabilized Finite Elements (1998)
    Details
    Publication Date: 2014-02-26
    Description: Fully adaptive solutions of imcompressible flow problems employing the discretization sequence first in time then in space are presented. The time discretization is done by linearly implicit one--step methods possibly of high order with automatic step size control. A posteriori error estimates for the stabilized finite element discretization in space are obtained by solving local Dirichlet problems with higher accuracy. Once those estimates have been computed, we are able to control time and space grids with respect to required tolerances and necessary computational work. The devised method is applied to two benchmark problems in 2D.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 32
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    Conjunctive Cuts for Integer Programs (1998)
    Details
    Publication Date: 2014-02-26
    Description: This paper deals with a family of conjunctive inequalities. Such inequalities are needed to describe the polyhedron associated with all the integer points that satisfy several knapsack constraints simultaneously. Here we demonstrate the strength and potential of conjunctive inequalities in connection with lifting from a computational point of view.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 33
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    Recursive Direct Algorithms for Multistage Stochastic Programs in Financial Engineering (1998)
    Details
    Publication Date: 2021-02-01
    Description: Multistage stochastic programs can be seen as discrete optimal control problems with a characteristic dynamic structure induced by the scenario tree. To exploit that structure, we propose a highly efficient dynamic programming recursion for the computationally intensive task of KKT systems solution within an interior point method. Test runs on a multistage portfolio selection problem demonstrate the performance of the algorithm.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 34
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    Simulation of the Transient Heating in an Unsymmetrical Coated Hot--Strip Sensor with a Self--Adaptive Finite Element Method (1998)
    Details
    Publication Date: 2019-05-10
    Description: The transient heating in an unsymmetrical coated hot--strip sensor was simulated with a self--adaptive finite element method. The first tests of this model show that it can determine with a small error the thermal conductivity of liquids, from the transient temperature rise in the hot--strip, deposited in a substrate and coated by an alumina spray.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 35
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    A counterexample to an integer analogue of Caratheodorys theorem (1998)
    Details
    Publication Date: 2014-02-26
    Description: For $n\geq 6$ we provide a counterexample to the conjecture that every integral vector of a $n$-dimensional integral polyhedral pointed cone $C$ can be written as a nonnegative integral combination of at most $n$ elements of the Hilbert basis of $C$. In fact, we show that in general at least $\lfloor 7/6 \cdot n \rfloor$ elements of the Hilbert basis are needed.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 36
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    Faber and Newton Polynomial Integrators for Open-System Density Matrix Propagation (1998)
    Details
    Publication Date: 2014-02-26
    Description: Two polynomial expansions of the time-evolution superoperator to directly integrate Markovian Liouville-von Neumann (LvN) equations for quantum open systems, namely the Newton interpolation and the Faber approximation, are presented and critically compared. Details on the numerical implementation including error control, and on the performance of either method are given. In a first physical application, a damped harmonic oscillator is considered. Then, the Faber approximation is applied to compute a condensed phase absorption spectrum, for which a semi--analytical expression is derived. Finally, even more general applications are discussed. In all applications considered here it is found that both the Newton and Faber integrators are fast, general, stable, and accurate.
    Keywords: ddc:000
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  • 37
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    Second Order Transitions in Quantum-Classical Molecular Dynamics (1998)
    Details
    Publication Date: 2014-02-26
    Description: Mixed quantum--classical models have attracted considerable interest due to the expectation that they correctly describe non--adiabatic processes of full quantum dynamics. One of these models, the so--called QCMD model, represents most degrees of freedom of the molecular system by the means of classical mechanics but an important, small portion of the system is modeled by a wavefunction: the wavefunction is nonlinearly coupled to the classical motion via a singularly perturbed Schrödinger equation. In extension to the analysis given by F.A.~Bornemann [{\em Homogenization in Time of Singularly Perturbed Mechanical Systems}, Lecture Notes in Mathematics, no.~1687, 1998, Springer, Berlin], the article presents an asymptotic expansion up to second order in the perturbation parameter. This result allows for the construction of new models and numerical integration schemes.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 38
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    Non-Adiabatic Effects in Quantum-Classical Molecular Dynamics (1998)
    Details
    Publication Date: 2014-02-26
    Description: In molecular dynamics applications there is a growing interest in mixed quantum-classical models. The article is concerned with the so-called QCMD model. This model describes most atoms of the molecular system by the means of classical mechanics but an important, small portion of the system by the means of a wavefunction. We review the conditions under which the QCMD model is known to approximate the full quantum dynamical evolution of the system. In most quantum-classical simulations the {\em Born-Oppenheimer model} (BO) is used. In this model, the wavefunction is adiabatically coupled to the classical motion which leads to serious approximation deficiencies with respect to non-adiabatic effects in the fully quantum dynamical description of the system. In contrast to the BO model, the QCMD model does include non-adiabatic processes, e.g., transitions between the energy levels of the quantum system. It is demonstrated that, in mildly non-adiabatic scenarios, so-called {\em surface hopping} extensions of QCMD simulations yield good approximations of the non-adiabatic effects in full quantum dynamics. The algorithmic strategy of such extensions of QCMD is explained and the crucial steps of its realization are discussed with special emphasis on the numerical problems caused by highly oscillatory phase effects.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 39
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    Fast Texture-Based Algorithms for Vector Field Visualization (1998)
    Details
    Publication Date: 2014-02-27
    Description: In this thesis we develop new methods for visualizing vector fields which specifically address three design goals: accuracy, performance, and cognition. Our methods will be general-purpose and can be applied to arbitrary vector fields in two- and three-dimensional space. The methodology behind our approach is {\em texture-based visualization}. Texture-based visualization methods imitate techniques known from experimental flow visualization, namely, the observation of randomly dispersed particles or dye injection patterns. Instead of depicting individual lines or symbols, a contiguous high-resolution image or texture is generated. This texture clearly reveals the directional structure of the field. In this way intuitive insight can be obtained and even small details of the field become visible. However, it remains unclear what kind of textures are best suited for our purpose. How do we generate them? Can we apply these methods in three-dimensional space? In particular, we focus on a technique known as {\em line integral convolution} or LIC. This method turns out to be quite versatile and well-suited for visualizing many interesting vector fields. LIC images display the integral curves or field lines of a vector field at high spatial resolution. Although conceptually quite simple, line integral convolution implies a number of interesting mathematical and algorithmic questions.
    Keywords: ddc:000
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 40
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    Wo ist der Opac der virtuellen Bibliothek?- Strukturen des Kooperativen Bibliotheksverbundes (1998)
    Details
    Publication Date: 2014-02-26
    Description: Als neue Herausforderung für die Bibliotheken stellen sich heute die vielfältigen Publikationsmöglichkeiten, die den Wissenschaften durch das Internet zur Verfügung stehen. Die neuen Arten der wissenschaftlichen Information zu erschließen, wird für die Bibliotheken zu den neuen Aufgaben gehören. Der Artikel diskutiert zunächst die Frage, inwieweit dabei die traditionell hohen Maßstäbe bei der bibliographischen Beschreibung und sachlichen Erschließung noch aufrechterhalten werden können. Der Autor plädiert in diesem Zusammenhang für ein reduziertes Erfassungsschema im Sinne des Dublin Core, da dieses gleichzeitig eine Arbeitsteilung zwischen Wissenschaftlern, die zu ihren eigenen Arbeiten Metadaten erstellen, und Bibliotheksmitarbeitern, die solche einfachen Beschreibungen nach professionellen Maßstäben weiterentwickeln, ermöglicht. Der zweite Teil der Arbeit stellt eine technische Interpretation des Kooperativen Bibliotheksverbundes Berlin-Brandenburg (KOBV) vor, den eine Expertengruppe als neue Informationsstruktur für diese Region vorgesehen hat. Das Modell des Kooperativen Bibliotheksverbundes sieht im Prinzip eine dezentrale Datenhaltung vor, bei der die Bibliotheken in lokale Bibliothekssysteme katalogisieren. Im Gegensatz zu traditionellen Verbünden verzichtet der KOBV auf einen Zentralkatalog. Die in den lokalen Systemen vorliegende Information hingegen wird den Nutzern über eine Suchmaschine erschlossen und zur Verfügung gestellt. Dabei wird vorausgesetzt, daß die Zielsysteme über offene Schnittstellen (Z39.50 und WWW) angesprochen werden können. Zur Optimierung der bibliothekarischen Arbeit im Sinne von Copy Cataloging und Copy Acquisition steht vor allem den KOBV-Partnern ein zentrales Fremddatenangebot sowie die in Deutschland verbreiteten Normdaten zur Verfügung. Mit der Kommunikation über das standardisierte Protokoll Z39.50 sind dabei sowohl der KOBV selbst als auch das Fremddatengebot virtuell skalierbar. Im Unterschied zu einem zentralistisch organisierten Bibliotheksverbund eröffnet der auf dezentralen Strukturen aufbauende Kooperative Bibliotheksverbunds auch die Möglichkeit, virtuelle Fachverbünde zu beispielsweise einer Disziplin zu bilden.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 41
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    Die Suchmaschine des KOBV - Spezifikation der Anforderungen (1998)
    Details
    Publication Date: 2014-02-26
    Description: Das vorliegende Papier spezifiziert die Anforderungen an die Suchmaschine im Kooperativen Biblotheksverbund Berlin- Brandenburg (KOBV). Die Suchmaschine realisiert einen virtuellen Union Catalog, der auch als virtueller OPAC im Netz ansprechbar ist. Die zentrale Suchmaschine fungiert als Gateway zwischen der WWW- und der Z39.50-Welt des Internet. Mit Hilfe der Suchmaschine wird der Zugriff auf die Bibliotheken des KOBV, auf Normdaten und Fremddaten sowie auf weitere Informationsanbieter außerhalb des KOBV (über Internet und andere Netze) ermöglicht. Auf die Suchmaschine greifen sowohl Bibliotheksmitarbeiter/innen als auch Endnutzer zu, d.h. sie muß unterschiedlichen Anwenderbedürfnissen gerecht werden.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 42
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    GOS Thesaurus--Handbuch zum Projekt: Sammlungsmanagement für kulturgeschichtliche Museen in den neuen Bundesländern (1998)
    Details
    Publication Date: 2014-02-26
    Description: Das GOS Thesaurus--Handbuch wurde für die Teilnehmer des von der Robert Bosch Stiftung geförderten Projekts zum Sammlungsmanagement für kulturgeschichtliche Museen in den neuen Bundesländern geschrieben. Es basiert auf verschiedenen vom Institut für Museumskunde gemeinsam mit dem ZIB durchgeführten Projekten und beschreibt mit zahlreichen Beispielen Struktur und Aufbau eines Thesaurus.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 43
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    Aspects of Set Packing, Partitioning, and Covering (1998)
    Details
    Publication Date: 2020-08-05
    Description: Diese Dissertation befaßt sich mit ganzzahligen Programmen mit 0/1 Systemen: SetPacking-, Partitioning- und Covering-Probleme. Die drei Teile der Dissertation behandeln polyedrische, algorithmische und angewandte Aspekte derartiger Modelle.
    Keywords: ddc:000
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 44
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    The Fourth-Order Difference Equation Satisfied by the Associated Orthogonal Polynomials of the Delta-Laguerre-HahnClass (1998)
    Details
    Publication Date: 2014-02-26
    Description: Starting from the $ D_{ \omega}$-Riccati Difference equation satisfied by the Stieltjes function of a linear functional, we work out an algorithm which enables us to write the unique fourth-order difference equation satisfied by the associated of any integer order of orthogonal polynomials of the $ \Delta$-Laguerre-Hahn class. Moreover, in classical situations (Meixner, Charlier, Kravtchouk and Hahn), we give explicitely these difference equations; and from Hahn difference equation, we recover by limit process the difference equations satisfied by the associated of classical discrete orthogonal polynomials and differential equations satisfied by the associated of classical continuous orthogonal polynomials.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 45
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    A Study of Genetic Algorithms solving a combinatorial Puzzle (1998)
    Details
    Publication Date: 2014-02-26
    Description: The suitability of Genetic Algorithms (GAs) to solve a combinatorial problem with only one solution is investigated. The dependence of the performance is studied for GA-hard and GA-soft fitness functions, both with a range of different parameter values and different encodings.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 46
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    Impact of Nonlinear Heat Transfer on Temperature Control in Regional Hyperthermia (1998)
    Details
    Publication Date: 2019-05-10
    Description: We describe an optimization process specially designed for regional hyperthermia of deep seated tumors in order to achieve desired steady--state temperature distributions. A nonlinear three--dimensional heat transfer model based on temperature--dependent blood perfusion is applied to predict the temperature. Using linearly implicit methods in time and adaptive multilevel finite elements in space, we are able to integrate efficiently the instationary nonlinear heat equation with high accuracy. Optimal heating is obtained by minimizing an integral object function which measures the distance between desired and model predicted temperatures. A sequence of minima is calculated from successively improved constant--rate perfusion models employing a damped Newton method in an inner iteration. We compare temperature distributions for two individual patients calculated on coarse and fine spatial grids and present numerical results of optimizations for a Sigma 60 Applicator of the BSD 2000 Hyperthermia System.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 47
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    Fourth Order Difference Equation for the Associated Classical Discrete Orthogonal Polynomials (1998)
    Details
    Publication Date: 2015-06-01
    Description: We derive the fourth order difference equation satisfied by the associated of order $\;r\;$ of the classical orthogonal polynomials of a discrete variable.\\The coefficients of this equation are given in terms of the polynomials $\; \sigma\;$ and $\;\tau\;$ which appear in the discrete Pearson equation $\;\;\Delta(\sigma\;\rho)=\tau\;\rho\;\;$ defining the weight $\;\rho(x)\;$ of the classical discrete orthogonal polynomials.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 48
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    Algorithms for q-hypergeometric Summation in Computer Algebra (1998)
    Details
    Publication Date: 2015-06-01
    Description: In this paper we present a short description of $q$-analogues of Gosper's, Zeilberger's, Petkov\v{s}ek's and related algorithms. Furthermore we introduce our corresponding MAPLE implementations and show how they can be applied to prove or even derive identities associated with $q$-series.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 49
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    Identification of Almost Invariant Aggregates in Reversible Nearly Uncoupled Markov Chains (1998)
    Details
    Publication Date: 2014-02-26
    Description: The topic of the present paper bas been motivated by a recent computational approach to identify chemical conformations and conformational changes within molecular systems. After proper discretization, the conformations show up as almost invariant aggregates in reversible nearly uncoupled Markov chains. Most of the former work on this subject treated the direct problem: given the aggregates, analyze the loose coupling in connection with the computation of the stationary distribution (aggregation/disaggregation techniques). In contrast to that the present paper focuses on the inverse problem: given the system as a whole, identify the almost invariant aggregates together with the associated transition probabilites. A rather simple and robust algorithm is suggested and illustrated by its application to the n-pentane molecule.
    Keywords: ddc:000
    Language: English
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  • 50
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    A Hybrid Monte Carlo Method for Essential Molecular Dynamics (1998)
    Details
    Publication Date: 2014-02-26
    Description: Recently, a novel concept for the computation of essential features of Hamiltonian systems (such as those arising in molecular dynamics) has been proposed. The realization of that concept was based on subdivision techniques applied to the Frobenius--Perron operator for the dynamical system. The present paper suggests an alternative but related concept based on statistical mechanics, which allows to attack realistic molecular systems. In a first step, the frequency of conformational changes is characterized in statistical terms leading to the definition of some Markov operator $T$ that describes the corresponding transition probabilities within the canonical ensemble. In a second step, a discretization of $T$ via hybrid Monte Carlo techniques (based on short term subtrajectories only) is shown to lead to a stochastic matrix $P$. With these theoretical preparations, an identification algorithm for conformations is applicable (to be presented elsewhere). Numerical results for the n-pentane molecule are given and interpreted.
    Keywords: ddc:000
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  • 51
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    Combinatorial Online Optimization in Practice (1998)
    Details
    Publication Date: 2014-02-26
    Description: This paper gives a short introduction into combinatorial online optimization. It explains a few evaluation concepts of online algorithms, such as competitiveness, and discusses limitations in their application to real--world problems. The main focus, however, is a survey of combinatorial online problems coming up in practice, in particular, in large scale material flow and flexible manufacturing systems.
    Keywords: ddc:000
    Language: English
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  • 52
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    GOS Benutzer--Handbuch. Anleitung zum Projekt: Sammlungsmanagement für kulturgeschichtliche Museen in den neuen Bundesländern (1998)
    Details
    Publication Date: 2016-09-01
    Description: Das Handbuch enthält eine ausführliche Einführung in das am ZIB für den Einsatz in der Museumsdokumentation entwickelte Datenbanksystem GOS.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 53
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    Kooperativer Bibliotheksverbund Berlin-Brandenburg - Strategien zur Nutzung von Fremddaten (1998)
    Details
    Publication Date: 2020-03-11
    Description: Ausgehend von einer Analyse der Fremddatenbedarfs in der Bibliotheksregion Berlin-Brandenburg wird überlegt, welche Fremddaten im neuen Kooperativen Bibliotheksverbund Berlin-Brandenburg (KOBV) in Zukunft an welchem Ort vorliegen sollten. Dabei wird konzeptionell eine Balance versucht zwischen den Daten, die zentral für die Region angeboten werden, den Daten, die die Bibliotheken (langfristig) über Z39.50 aus (verbund-) fremden Bibliotheken abrufen, und denjenigen Datenbeständen, die ausschließlich zur lokalen Nutzung vorliegen.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 54
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    Kooperativer Bibliotheksverbund Berlin-Brandenburg - Lokale Konzepte und technische Schnittstellen (1998)
    Details
    Publication Date: 2014-02-26
    Description: Dieser Artikel faßt die Ergebnisse einer Arbeitsgruppe bestehend aus Bibliothekaren und Informatikern der Universitäts- und Hochschulbibliotheken aus Berlin und Brandenburg zusammen, welche sich im Frühjahr 1997 zusammengefunden hatte, um die Anforderungen an den Kooperativen Bibliotheksverbund Berlin-Brandenburg (KOBV) aus Sicht der betroffenen Institutionen zu diskutieren. Dieser Verbund verzichtet zugunsten einer verteilten Datenhaltung in den jeweiligen lokalen Bibliothekssystemen auf einen Zentralkatalog und realisiert statt dessen mittels einer Suchmaschine einen virtuellen Union-Katalog, der auch als OPAC im Internet zur Verfügung steht. Zusätzlich soll zur Unterstützung der Erwerbungs- und Katalogisierungsarbeit der wissenschaftlichen Bibliotheken ein Fremd- und Normdatenserver errichtet werden. Beschrieben werden neben den erforderlichen Internet-Schnittstellen (WWW, Z39.50), das Fremd- und Normdatenangebot als auch konkrete Anforderungen an die Suchmaschine. Dabei wird die Sicht der Bibliotheksmitarbeiter ebenso wie die der Bibliotheksbenutzer berücksichtigt.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 55
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    Abschlussbericht für das Projekt: Sammlungsmanagement für kulturgeschichtliche Museen in den neuen Bundesländern (1998)
    Details
    Publication Date: 2016-09-01
    Description: Von Januar 1995 bis Februar 1997 wurde am ZIB ein von der Robert Bosch Stiftung gefördertes Projekt zum Sammlungsmanagement für kulturgeschichtliche Museen in den neuen Bundesländern durchgeführt. In dem vorliegenden Abschlußbericht werden die Ziele, die Strategie, die Durchführung und die Ergebnisse des Projekts beschrieben.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
    Format: application/postscript
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  • 56
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    Systemanalyse und Datenkatalog zum Projekt: Sammlungsmanagement für kulturgeschichtliche Museen in den neuen Bundesländern (1998)
    Details
    Publication Date: 2014-02-26
    Description: Von Januar 1995 bis Februar 1997 wurde am ZIB ein von der Robert Bosch Stiftung gefördertes Projekt zum Sammlungsmanagement für kulturgeschichtliche Museen in den neuen Bundesländern durchgeführt. Die vorliegende Systemanalyse beschreibt exemplarisch die Voraussetzungen und die notwendigen Arbeitsschritte für den Aufbau einer Dokumentation in einem Museum. Ein im Anhang wiedergegebener Datenfeldkatalog hilft beim "`sanften"' Übergang von einer papiergestützten zu einer computergestützten Dokumentation.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
    Format: application/postscript
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  • 57
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    The Orientation Model for Frequency Assignment Problems (1998)
    Details
    Publication Date: 2020-03-09
    Description: Mobile telecommunication systems establish a large number of communication links with a limited number of available frequencies; reuse of the same or adjacent frequencies on neighboring links causes interference. The task to find an assignment of frequencies to channels with minimal interference is the frequency assignment problem. The frequency assignment problem is usually treated as a graph coloring problem where the number of colors is minimized, but this approach does not model interference minimization correctly. We give in this paper a new integer programming formulation of the frequency assignment problem, the orientation model, and develop a heuristic two-stage method to solve it. The algorithm iteratively solves an outer and an inner optimization problem. The outer problem decides for each pair of communication links which link gets the higher frequency and leads to an acyclic subdigraph problem with additional longest path restrictions. The inner problem to find an optimal assignment respecting an orientation leads to a min-cost flow problem.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 58
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    Mehrschichtige Oberflächenmodelle zur computergestützten Planung in der Chirurgie (1998)
    Details
    Publication Date: 2019-01-24
    Description: Polygonale Schädelmodelle bilden ein wichtiges Hilfsmittel für computergestützte Planungen im Bereich der plastischen Chirurgie. Wir beschreiben, wie derartige Modelle automatisch aus hochaufgelösten CT-Datensätzen erzeugt werden können. Durch einen lokal steuerbaren Simplifizierungsalgorithmus werden die Modelle so weit vereinfacht, daß auch auf kleineren Graphikcomputern interaktives Arbeiten möglich wird. Die Verwendung eines speziellen Transparenzmodells ermöglicht den ungehinderten Blick auf die bei der Planung relevanten Knochenstrukturen und läßt den Benutzer zugleich die Kopfumrisse des Patienten erkennen.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
    Format: application/postscript
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  • 59
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    Bibliothekarische Inhalte und Zielsetzungen des KOBV (1998)
    Details
    Publication Date: 2020-11-13
    Description: Der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) wurde 1997 auf politische Initiative hin gegründet, um für die ressourcenreiche, aber elektronisch unzulänglich erschlossene Bibliotheksregion Berlin-Brandenburg eine moderne Informationsinfrastruktur zu schaffen. Auf der Basis eines Expertengutachtens wird sowohl in technischer als auch in organisatorischer Hinsicht ein neues Kooperationsmodell entwickelt, das auf den Prinzipien der Dezentralisierung, Deregulierung und Kooperation beruht. Der vorliegende Artikel ist das Ergebnis einer bibliothekarischen Arbeitsgruppe des KOBV, die von Dezember 1997 bis März 1998 das Modell des KOBV unter bibliothekarischen Gesichtspunkten diskutiert hat. Es werden erste Leitlinien festgelegt zu den Serviceleistungen des KOBV, zu den Prinzipien der Zusammenarbeit der Bibliotheken untereinander sowie zur Einbindung des Verbundes in das Bibliothekswesen der Bundesrepublik. Damit dient der Artikel zugleich der Positionsbestimmung des KOBV innerhalb des deutschen Bibliothekswesens.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 60
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    Client-Server-Anwendung zur Steuerung von Ausgabegeräten (1998)
    Details
    Publication Date: 2020-03-11
    Description: \\{\bf Zusammenfassung: }\noindent Die Steuerung von grafischen Ausgabegeräten erfordert oft mehr als ein oder zwei Optionen, wie man sie vom UNIX {\em lpr}-Kommando kennt. Hier bietet sich eine grafische Benutzungsschnittstelle zur übersichtlichen Einstellung aller möglichen Parameter und Optionen an. Wenn dieses Gerät zudem nur über eine besondere Treiber-Software zu bedienen ist und in einem heterogenen Intranet zur Verfügung gestellt werden soll, ist eine Steuerung mittels eines WWW-Servers naheliegend. Im Folgenden sollen Lösungsansätze diskutiert werden, die auf HTML/CGI- bzw. Java-Basis derartige Steuerung realisieren. {\small} It is often the case that graphical output devices need more than one or two control options like the UNIX {\em lpr}-command. A driver programme with a graphical user interface (GUI) can satisfy this requirement. If such a device shall be accessible in an heterogenous network a solution using a WWW-server can be used. Possible HTML/CGI resp. Java-based solutions are discussed in the following.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 61
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    A simple C++ library for manipulating scientific data sets as structured data (1998)
    Details
    Publication Date: 2014-02-26
    Description: Representing scientific data sets efficiently on external storage usually involves converting them to a byte string representation using specialized reader/writer routines. The resulting storage files are frequently difficult to interpret without these specialized routines as they do not contain information about the logical structure of the data. Avoiding such problems usually involves heavy-weight data format libraries or data base systems. We present a simple C++ library that allows to create and access data files that store structured data. The structure of the data is described by a data type that can be built from elementary data types (integer and floating-point numbers, byte strings) and composite data types (arrays, structures, unions). An abstract data access class presents the data to the application. Different actual data file structures can be implemented under this layer. This method is particularly suited to applications that require complex data structures, e.g. molecular dynamics simulations. Extensions such as late type binding and object persistence are discussed.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 62
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    Jahresbericht 1997 (1998)
    Details
    Publication Date: 2019-10-24
    Keywords: ddc:000
    Language: German
    Type: annualzib , doc-type:report
    Format: application/pdf
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  • 63
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    Math-Net: Ein Informationssystem der Mathematik (1998)
    Details
    Publication Date: 2022-04-11
    Description: In diesem Artikel geben wir einen Überblick über das Math-Net-Projekt. Wir berichten über die organisatorischen und technischen Vorgehensweisen beim Aufbau eines verteilten Informationssystems für die Mathematik in Deutschland.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 64
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    An Alternative Derivation of the Exact DtN-Map on a Circle (1998)
    Details
    Publication Date: 2022-07-07
    Description: The paper supplies an alternative derivation of the exact boundary conditions needed for the solution of time-harmonic acoustic scattering problems modeled by the Helmholtz equation. The main idea is to consider the exterior domain problem as an initial value problem with initial data given on the boundary of a disc or sphere. The solution of the exterior domain problem is obtained via Laplace transformation techniques, where the asymptotic Sommerfeld radiation condition is reformulated accordingly.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 65
    Electronic Resource
    Electronic Resource
    Sample preparation for photometric determination of histamine in foodstuffs compared with capillary electrophoresis (1998)
    Springer
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 206 (1998), S. 246-250 
    Details
    ISSN: 1431-4630
    Keywords: Key words Histamine ; Capillary electrophoresis ; Photometric determination ; Liquid liquid extraction ; Solid phase extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  To determine levels of histamine, two methods were used, photometry in conjunction with two sample clean-up procedures, and capillary zone electrophoresis (CZE). The two sample clean-up procedures used were liquid liquid extraction (LLE) with n-butanol and solid phase extraction (SPE). Using CZE, the separation of histamine from the matrix was good. The other method, photometry, represents a classic and simple method, that can be employed for in situ measurement of histamine. We found that it was necessary to clean up the samples prior to photometry; if this was not done, the recorded levels of histamine were higher than those determined by CZE. In order to determine levels of histamine, both of these rapid tests were applied to ten different foodstuffs. The levels of histamine measured using photometry following either LLE or SPE were compared. The results indicated that photometry is a suitable method for the measurement of histamine, although the sample solutions have to be purified by either LLE or SPE. Samples do not need to be cleaned up before CZE because there is no interference between histamine and attendant material. Both sample clean-up procedures were applied to the following foodstuffs: tomatoes, sauerkraut, tuna, leaf spinach, cream spinach, white wine and mackerel. The differences of the measured values vary between 3% and 18% for LLE and 6% and 27% for SPE. For the other foodstuffs, such as beef, beer and non-alcoholic beer, only one sample clean-up procedure is suitable. LLE used for beef and beer leads to differences in measured levels of histamine between 18% and 50%, respectively, whereas SPE used for non-alcoholic beer leads to differences of 20%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002170050252
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  • 66
    Electronic Resource
    Electronic Resource
    Mixing in Stars and the Evolution of the 3He Abundance (1998)
    Springer
    Space science reviews 84 (1998), S. 199-206 
    Details
    ISSN: 1572-9672
    Keywords: Nuclear reactions ; Nucleosynthesis ; Abundances ; Stars:Evolution ; Interior ; Rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We first recall the observational and theoretical facts that constitute the so-called 3He problem. We then review the chemical anomalies that could be related to the destruction of 3He in red giants stars. We show how a simple consistent mechanism can lead to the destruction of 3He in low mass stars and simultaneously account for the low 12C/13C ratios and low lithium abundances observed in giant stars of different populations. This process should both naturally account for the recent measurements of 3He/H in galactic HII regions and allow for high values of 3He observed in some planetary nebulae. We propose a simple statistical estimation of the fraction of stars that may be affected by this process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005027519798
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  • 67
    Electronic Resource
    Electronic Resource
    Capillary zone electrophoretic separation of basic proteins and drugs using guaran as a buffer modifier (1998)
    Springer
    Chromatographia 47 (1998), S. 219-224 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Beta-blockers ; Protein separation ; Drug separation ; Guaran ; Buffer modifier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Guaran, a neutral polysaccharide, has been used as a buffer modifier to improve the separation of basic proteins and drugs. Migration reproductibility, peak shape and efficiency were improved when 0.1% guaran was added to the buffer. The concentration of guaran, ionic strength, and pH of buffer solution were optimized to obtain the optimum separation of proteins. Possible separation efficiencies of 700,000 plates per meter were obtained for test proteins. The relative standard deviation (% RSD) of the migration time of all test proteins was less than 0.5%. Improved separation of β-blockers was also observed when guaran was added to the buffer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466585
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  • 68
    Electronic Resource
    Electronic Resource
    Characterization of humic-like substances in airborne particulate matter by capillary electrophoresis (1998)
    Springer
    Chromatographia 47 (1998), S. 619-624 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Airborne particles ; Humic-like substances
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A considerable fraction of the refractory organic carbon in airborne particulate matter is to be attributed to humic-like substances (HULIS). Such atmospheric HULIS isolated from different air dust samples by a microscale extraction procedure were characterized by capillary electrophoresis (CE). For fractionation of HULIS the working conditions of the CE system were optimized using a borate buffer (pH 8.2), polyacrylamide (PAA) coated, fused-silica capillary and polyethylene glycol as sieving modifier. Using CE under optimized conditions, HULIS produced electropherograms showing well resolved and reproducible signals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467443
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  • 69
    Electronic Resource
    Electronic Resource
    Rapid and reproducible capillary electrophoretic separation of double-stranded DNA fragments in a simple methyl cellulosic sieving system (1998)
    Springer
    Chromatographia 47 (1998), S. 125-134 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; DNA fragments ; Cellulose derivatives ; Sieving cellulose matrix
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid, robust and reproducible method providing excellent separation performance and simplicity using a 0.5% MC-4000 methyl cellulosic sieving medium in DB-1 coated capillaries has been developed. The method is suitable for qualitative comparison of DNA restriction profiles for fragments in the size range 100–1000 base pairs (bp). Efficiencies up to 8.5 million plates/m (1057 bp fragment) were recorded. Peak resolution of 6 bp (291/297 bp, 335/341 bp) and 4 bp (238/242 bp, 341/345 bp) was achieved. In addition, 1 bp partial resolution of 123/124 bp and 298/297 bp was obtained. Run-to-run (n=15), day-to-day (n=4), and capillary-to-capillary (n=3) variations of 0.1–0.2% RSD, 0.3–0.5% RSD, and 0.1–0.3% RSD, respectively, were observed. The MC-4000 sieving matrix was found to be better than hydroxypropyl methyl cellulose and hydroxypropyl cellulose, in terms of both performance and stability in the DB-1 coated capillaries. The efficiency and resolution in DB-WAX capillaries were inferior to those obtained in DB-1 capillaries. The commercially available DB-1 capillaries were stable for months in the sieving medium at pH 8.3 and could be regenerated to provide high efficiency after accidental current breaks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466571
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  • 70
    Electronic Resource
    Electronic Resource
    Capillary electrophoretic study of the complexation of nucleotides with magnesium and calcium ions (1998)
    Springer
    Chromatographia 48 (1998), S. 739-744 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Nucleotides ; Inorganic cations ; Complexation with Mg and Ca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The complexation equilibrium between nucleotides (ATP, ADP) and inorganic cations (Mg2+, Ca2+) has been studied by capillary electrophoresis. The equilibrium constant and the stoichiometry of nucleotide-inorganic cation complexes can be deduced from the dependence of the electrophoretic mobility of each nucleotide on the negative logarithm of the inorganic cation concentration. The experimental values of complexation constants determined by CE compare favorably with those in the literature. As expected, Mg2+ forms more stable complexes with ATP (logK=2.30 and 4.10 at pH 5 and 8, respectively) than with ADP (logK=1.92 and 3.15 at pH 5 and 8, respectively). In the pH range 4–8, the stoichiometry of ADP-Mg2+ and ADP-Ca2+ complexes is always 1∶1 whereas that of the complexes between these cations and ATP depends on pH-hence ATP-Mg2+ and ATP-Ca2+ complexes have 1∶1 stoichiometry at pH 5 and 1∶2 at pH 8.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467641
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  • 71
    Electronic Resource
    Electronic Resource
    Peak recognition imitating human judgement (1998)
    Springer
    Chromatographia 48 (1998), S. 331-346 
    Details
    ISSN: 1612-1112
    Keywords: Peak integration ; Baseline determination ; Quantitation ; Capillary electrophoresis ; Chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Peak integration is still a major source of error in analytical techniques such as chromatography (LC and GC), aapillary electrophoresis (CE), spectrosocpy, and electrochemistry. If the baseline is complex, e.g. because of matrix effects, or if the peak shape is irregular, e.g. because of peak tailing, the results are often not satisfactory when classical procedures are used. These shortcomings arise because of the stepwise appearance of the chromatogram. An algorithm that copies the human method of considering baseline and peaks as a whole has already been introduced. Here the use of a straight line as a baseline model led to an improvement in several instances. The baseline is, however, usually not exactly straight and rigid. A baseline model with flexible properties is more advantageous. Thus the smoothing cubic spline function is applied in this work. Here the rigidity can be controlled by use of a parameterp k. The prediction interval of the spline is used for iterative distinction between baseline and peak regions. Afterwards straightforward optimization of the peak boundaries is applied. More than 50 series of consecutive injections of the same sample (n=40 on average) were used to test the performance of this procedure. The same raw data have been integrated by means of the algorithm described here and by use of commercially available software. The reproducibility of the main component peak are within the series was taken as a measure of integration quality. Typically the new procedure reducesRSD % by approximately 33% (e.g. from 1.5% to 1.0%). The improvement is even more impressive for difficult samples with complex matrices, e.g. blood plasma or polymer excipients. for such samples improvements of up to a factor of 6 are obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467701
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  • 72
    Electronic Resource
    Electronic Resource
    Experimental design methodologies to optimize the CE separation of epinephrine enantiomers (1998)
    Springer
    Chromatographia 48 (1998), S. 395-401 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Enantiomers ; Epinephrine ; Experimental designs ; Optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A capillary electrophoretic method using a chiral selector was optimized by experimental design for the enantioresolution of epinephrine enantiomers. Two β-cyclodextrins derivatives, namely heptakis-2,6-di-O-methyl-β-cyclodextrin and carboxy-methyl-β-cyclodextrin, respectively neutral and charged, were used as chiral selectors employing an uncoated capillary. By using a statistical experimental design in which all factors are varied at the same time, it was possible to optimize the method with regard to the resolution between peaks and the two migration times. A fractional factorial design and a central composite design were used. A compromise between conflicting goals, such as maximization of resolution and minimization of analysis time, was found by means of a desirability function D. Balancing these goals against each other, the most acceptable solution to the problem was found and the optimized method gave a fast separation with complete resolution between the adrenaline enantiomers. The response surfaces obtained confirmed the robustness of the method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467710
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  • 73
    Electronic Resource
    Electronic Resource
    Capillary gel electrophoresis of oligonucleotides using polymer solutions (1998)
    Springer
    Chromatographia 48 (1998), S. 569-575 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Oligonucleotides ; Dextran ; Polymer solution ; Purity testing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Capillary gel electrophoresis (CGE) has been recognized as an effective method for the analysis of oligonucleotides. CGE using polymer solutions is especially useful and effective compared with that using crosslinked gels, because of easy change of media. Replacement of media leads to the reproducible separation of analytes. We have investigated CGE analysis of oligonucleotides of less than 20 bases employing various kinds of polymers. Polyacrylamide, dextrin, dextran, pullakin, and poly(ethylene glycol) were used as sieving matrixes at concentrations of 0–30 %. Polydeoxythymidylic acids [p(dT)11–20] were used as a test sample. These small oligonucleotides were successfully resolved on the basis of their base number by CGE using some of these polymer solutions. In particular, dextran was found to be effective and baseline separation was observed when a 30 % dextran solution was employed. Some validations such as linearity and reproducibility were also established and this method was found to be an adequate quality control method for small oligonucleotides. Finally, CGE using a 30 % dextran solution was successfully applied to impurity profiling of some synthetic oligonucleotides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466651
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  • 74
    Electronic Resource
    Electronic Resource
    Effects of buffer depletion in capillary electrophoresis: Development of a continuous flow cathode (1998)
    Springer
    Chromatographia 48 (1998), S. 355-359 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Cathodic flow electrode ; Electrolyte buffer depletion ; Reproductibility and precision
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effects of electrolyte buffer depletion is well recognised and regular replacement of the electrolyte can prevent poor reproducibility. We have further investigated the effect of electrolyte depletion and produced a modified cathodic flow electrode to improve reproducibility using minimal volumes of electrolytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467703
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  • 75
    Electronic Resource
    Electronic Resource
    Determination of weak (2.0–2.5) dissociation constants of non-UV absorbing solutes by capillary electrophoresis (1998)
    Springer
    Chromatographia 48 (1998), S. 529-534 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; pK A determination ; Indirect UV detection ; Alkyl-alkyl phosphonic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Capillary electrophoresis (CE) has proved to be a fast and convenient method for the determination of the dissociation constants of non-UV absorbing solutes in the acidic pK A range (2.0–2.5). The electroosmotic flow was reversed by washing the capillary with 0.2% polybren aqueous solution. A series of background electrolytes was prepared with phenylphosphonic acid (pK A=1.29) and β-alanine (pK A=3.55) with the same ionic strength and a high buffer capacity in order to improve the repeatability (0.1–0.2 %) of the electrophoretic mobility and to determine the values of pK A accurately. This procedure was applied to the determination of the dissociation constants of several alkyl-alkylphosphonic acids whose pK A values have not yet been published in the literature. In this work, their dissociation constants have been found to vary between 1.91 and 2.34 for alkyl-methylphosphonic acids and between 2.10 and 2.38 for alkyl-ethylphosphonic acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466645
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    A standard addition method for the quantitative determination of succinic acid and levulinic acid in processed acid stream extracts employing indirect UV capillary electrophoresis (1998)
    Springer
    Chromatographia 47 (1998), S. 709-715 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Succinic and levulinic acid ; Indirect UV detection ; Standard addition method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper describes an capillary electrophoresis (CE) method used to quantify both succinic acid and levulinic acid in an industrial production process. Measurement was performed by CE with indirect UV detection, using potassium hydrogen phthalate as the UV-absorbing additive. The electrolyte composition used was 5 mM potassium hydrogen phthalate at pH 7.0 containing 0.25 mM cetyl trimethylammonium bromide (CTAB) as an electrosmotic flow (EOF) modifier to reverse the EOF. The method provides for improved sensitivity by employing an extended path length capillary, and for identification and quantification by the use of a standard addition method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467458
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  • 77
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    Electronic Resource
    High-performance capillary electrophoretic analysis of synthetic food colorants (1998)
    Springer
    Chromatographia 47 (1998), S. 249-256 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Cyclodextrin mobile phase additives ; Synthetic food colorants ; Selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high-performance capillary electrophoresis method with diode-array detection has been developed for analysis of synthetic food colorants. The influence of buffer composition on the separation of the food colorants was examined, as were the effects of α-, β- and γ-c-yclodextrins on analyte migration behavior. Eight food colorants were completely separated within 10 min using pH 9.5 borax—NaOH buffer containing 5 mM β-cyclodextrin. Experimental results indicate that the relative standard deviations of analyte migration times were〈0.88% under the optimized separation condition. Correlation coefficients of the linear calibration plots of the analytes exceeded 0.998. The method was suitable for determination of the quantities of synthetic food colorantsi in ice cream bars and fruit soda drinks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466528
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  • 78
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    Electronic Resource
    Determination of aldehydes in water samples by capillary electrophoresis after derivatization with hydrazino benzene sulfonic acid (1998)
    Springer
    Chromatographia 48 (1998), S. 807-810 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Aldehydes ; Hydrazino benzene sulfonic acid ; Water analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method has been developed for the analysis of environmentally important aldehydes in rain water. The method is based on the derivatization of the aldehydes with hydrazino benzene sulfonic acid, separation of the hydrazones formed by capillary electrophoresis and UV detection at 280 nm. Derivatization was shown to be complete in 15 min at 50°C. The aldehyde derivatives could be separated from each other and from the excess of reagent using a pH 9 borate buffer as background electrolyte, with an analysis time of less than 6 min. The repeatability was better than 0.5% for the peak mobilities and in the order of 2–5% for the peak areas. Detection limits of 0.8–3 μmol L−1 (0.02–0.2 ppm) were obtained. The method was applied for the determination of formaldehyde and acetaldehyde in rain water samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467652
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  • 79
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    Electronic Resource
    The effect of conductivity tuning in chiral separations by CE; Using hydroxypropyl-β-cyclodextrin in combination with tetraalkylammonium ions (1998)
    Springer
    Chromatographia 48 (1998), S. 415-421 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Conductivity tuning ; Chiral separation ; Peak symmetry ; Resolution expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Different approaches how to handle the electromigration dispersion process that occurs in separation and determination of enantiomers are presented. The use of cyclodextrins as chiral selectors in resolution enantiomers involves the possibility to tune the conductivity of the sample band in order to obtain symmetrical and efficient peaks. Determination of impurities that migrate in the rear part of an overloaded main peak can be accomplished if the conductivity of the background electrolyte (BGE) is adapted to the conductivity of the sample band. This strategy was shown in determination of the content of D-sotalol in a mixture of L and D-sotalol. The efficiency and the symmetry of the overloaded L-sotalol peak was substantially improved by substitution of tetrabutylammonium ions for tetrapentylammonium ions as co-ions in the BGE. In this system it was possible to determine 0.2% w/w of the chiral impurity D-sotalol. A resolution model is presented and used qualitatively in the study where the complexation between the tetraalkyllammonium ions and the cyclodextrins is taken into account.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467713
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  • 80
    Electronic Resource
    Electronic Resource
    Capillary ion analysis of potassium concentrations in human vitreous humor (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 6-10 
    Details
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Vitreous humor ; Potassium ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Capillary ion analysis (CIA) is a form of capillary electrophoresis which uses the differential electrophoretic mobility of ions to perform a separation of an ionic mixture. Application of this technique for direct detection of potassium concentrations in human vitreous humor was the purpose of this investigation. CIA was performed using a Waters Quanta 4000 Capillary Electrophoresis System with a 745 Data Module using a 75 μm × 60 cm capillary and a run electrolyte of 67.7 mg hydroxyisobutyric acid (HIBA), 52.8 mg 18-crown-6 ether and 64 μL UV-CAT-1 reagent (4-ethylbenzylamine) in a volume of 100 mL water (18 Mohm) with a voltage of 20 kV using ultraviolet absorption detection at 214 nm. Migration times were: ammonium ion, 2.86 min; potassium, 3.24 min; calcium, 3.84 min; sodium, 3.98 min; barium (internal standard), 4.68 min; and lithium, 4.79 min. Correlation coefficients (r) between peak area ratios and concentration ranges of 2.5-144 mmole/L (100-1000 ppm) were from 0.9855 to 0.9999. Coefficients of variation (CV) ranged from 1.45 to 13.8% between days and from 1.38 to 9.43% within-day. Application of this methodology to twenty-five vitreous humor specimens from forensic cases was compared to analysis by ion-specific electrode for potassium concentration. Comparison of CIA to ion-specific electrode analysis of vitreous humor potassium concentrations revealed a correlation coefficient of 0.9642. CIA is applicable to forensic analysis of potassium concentration in forensic vitreous humor specimens. Quantitation of numerous cation concentrations is possible by direct CIA of vitreous humor.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190104
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  • 81
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    Electronic Resource
    DNA fingerprinting of Listeria monocytogenes using enterobacterial repetitive intergenic consensus (ERIC) motifs-polymerase chain reaction/capillary electrophoresis (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 66-70 
    Details
    ISSN: 0173-0835
    Keywords: DNA fingerprinting ; Capillary electrophoresis ; Polymerase chain reaction ; Entobacterial repetitive intergenic consensus motifs ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The molecular technique, enterobacterial repetitive intergenic consensus (ERIC)-polymerase chain reaction (PCR) produces genomic DNA fingerprint that discriminate bacterial species and strains. This technique was applied to the characterization of Listeria monocytogenes, an important food-borne pathogen implicated in numerous cases of listeriosis. The ERIC-PCR resulted in distinct DNA fingerprinting patterns of all L. monocytogene serotypes and Listeria species. Analysis of the genomic DNA fingerprints was accomplished using capillary electrophoresis (CE), an alternative technique to the conventional agarose gel method. The optimization of CE conditions (electrokinetic injection, applied voltage) resulted in the resolution of amplified DNA fragments up to 1000 bp. Comparisons of electropherograms provided genomic fingerprint templates which could be further used for supplementary information. The ERIC-PCR method coupled to CE provides a rapid technique in differentiating bacterial spp., and may contribute relevant information in food-borne outbreak studies.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190112
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  • 82
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    Electronic Resource
    Capillary electrophoresis of peptides and proteins in fused-silica capillaries coated with derivatized polystyrene nanoparticles (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 262-269 
    Details
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Proteins ; Peptides ; Derivatized polystyrene nanoparticles ; Coated capillary ; Hydrophilic surface ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: High-resolution capillary electrophoretic separation of proteins and peptides was achieved by coating the inner wall of 75 μm ID fused-silica capillaries with 40-140 nm polystyrene particles which have been derivatized with α-ω-diamines such as ethylenediamine or 1, 10-diaminodecane. A stable and irreversibly adsorbed coating was obtained upon deprotonation of the capillary surface with aqueous sodium hydroxide and subsequent flushing with a suspension of the positively charged particles. At pH 3.1, the detrimental adsorption of proteins to the capillary inner wall was suppressed efficiently because of electrostatic repulsion of the positively charged proteins from the positively charged coating which enabled protein separations with maximum efficiencies of 400 000 plates per meter. A substantial improvement of separation efficiency in particle-coated capillaries was observed after in-column derivatization of amino functionalities with 2,3-epoxy-1-propanol, resulting in a more hydrophilic coating. Five basic and four acidic proteins could be separated in less than 7 min with efficiencies up to 1 900 000 theoretical plates per meter. Finally, coated capillaries were applied to the high-resolution analysis of protein glycoforms and bioactive peptides.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190220
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  • 83
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    Electronic Resource
    Fast detection of a (CA)18 microsatellite repeat in the IgE receptor gene by capillary electrophoresis with laser-induced flurescence detection (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 249-255 
    Details
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Laser-induced fluorescence ; Microsatellite repeat ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The optimum separation conditions of polymerase chain reaction (PCR) products have been found for high-speed capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection. DNA fragments obtained after PCR amplification of the region covering the (CA)18 microsatellite repeat in nitron 5 of the gene for FcERIβ, a high affinity glycoprotein receptor for IgE, located on chromosome 11 (11q13), were analyzed with the aim of investigating the repeat polymorphism. The results of polyacrylamide slab gel electrophoresis (PAGE), agarose gel electrophoresis, CE with absorbance detector and CE with LIF are compared. The CE with LIF proved to shorten analysis time by a factor of 100 when compared to slab gel electrophoresis. CE-LIF utilizes a short capillary with an effective length of 6.3 cm and electric field strength from 100 to 550 V/cm. The respective PCR products of sizes from 116 to 210 base pairs (bp) were analyzed in 3 min.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190218
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  • 84
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    Electronic Resource
    Selenium speciation by interfacing capillary electrophoresis with inductively coupled plasma-mass spectrometry (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 270-275 
    Details
    ISSN: 0173-0835
    Keywords: Selenium ; Speciation ; Capillary electrophoresis ; Inductively coupled plasma mass spectrometry ; Hyphenation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The high resolution potential of capillary electrophoresis (CE) makes CE techniques valuable for separations of selenium species. Further, inductively coupled plasma-mass spectrometry (ICP-MS) affords element-specific multi-element detection, providing extremely low detection limits. The combination of CE with ICP-MS promises to become a powerful tool for metal speciation. Therefore, an on-line hyphenation of CE with ICP-MS, which was developed earlier (Michalke, B., Schramel, P., Fresenius' J. Anal. Chem. 1997, 257, 594-599), was modified and applied to selenium speciation. For this reason, capillary zone electrophoresis (CZE) methods were developed, providing the possibility to analyze six Se species of interest in one run: Se (IV), Se (VI), selenium carrying glutathione (GSSeSG), selenomethionine (SeM), selenocystine (SeC), and selenocystamine (SeCM). The final CE method used an alkaline background electrolyte (Na2CO3/NaOH) with separation differentiated from the detection step during hyphenation. This resulted in short separation times (10 min) and a subsequent detection step of 100s. The Se species were sufficiently separated from each other and appeared at 7s (SeCM), 16s (Se (VI)), 22s (SeC), 27s (Se (IV)), 35s (SeM) and 56s (GSSeSG) during the detection step. Detection limits were calculated as 10 or 20 μg Se/L for inorganic Se species and 35-50 μg Se/L for organic Se species.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190221
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  • 85
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    Electronic Resource
    Using capillary electrophoresis/frontal analysis to screen drugs interacting with human serum proteins (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 448-454 
    Details
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Frontal analysis ; Serum protein binding ; β-Blockers ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: We have used capillary electrophoresis in the frontal analysis mode (CE/FA) to determine the binding capacity of β-adrenoceptor blocking drugs to individual serum proteins, serum protein mixtures and human serum. The free drug concentration was directly measured from the height of the frontal peak and used to calculate the bound drug concentration. From the bound drug concentration, the percentage of drug bound to the serum proteins α1-acid glycoprotein (AGP) and human serum albumin (HSA) was then determined. In addition to determining the percent of a drug bound to a protein, the drug-protein association constant (Ka) was determined for AGP binding to β-blockers. The data-estimated association constants were consistent with literature values. The CE/FA studies on the β-adrenoceptor blocking drugs and the serum proteins indicated that HSA, AGP, high density lipoprotein (HDL), and low density lipoprotein (LDL) were the main contributors to serum binding for this series of compounds. The serum-drug binding data sorted the β-adrenoceptor blocking drugs into high and low binding categories. The protein mixture (AGP + HSA + HDL + LDL) resulted in dividing the β-blockers into the same high/low rankings. The protein mixture (AGP + HSA + HDL + LDL) was amenable to automation, did not autoaggregate, and had constant concentrations for the proteins.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190315
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  • 86
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    Electronic Resource
    High resolution capillary electrophoretic separation of oligonucleotides in low-viscosity, hydrophobically endcapped polyethylene oxide with cubic order (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 1699-1703 
    Details
    ISSN: 0173-0835
    Keywords: Oligonucleotides ; Capillary electrophoresis ; Self-associating polymer ; Physical gel ; End-capped polyethylene oxide ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A triblock self-associating polymer with the structure n- dodecane-poly(ethylene oxide)-n-dodecane and a very low polydispersity has been used as a matrix to separate a sample of single-stranded oligonucleotides containing Pd(A)25-30 and Pd(A)40-60. Above a concentration of 4%, this associative polymer forms a micellar network with cubic order and a well-defined micellar spacing, in which the dodecane micellar cores are bridged by polyoxyethylene segments. This medium combines a low viscosity with excellent resolution of oligonucleotides. This work confirms that associative polymers are potentially powerful media for separation in capillary electrophoresis, and argues in favor of the use of monodisperse products presenting a high-order in the physical gel state.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191029
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  • 87
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    Electronic Resource
    On-line partial filling micellar electrokinetic capillary chromatography-electrospray ionization-mass spectrometry of corticosteroids (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 1711-1718 
    Details
    ISSN: 0173-0835
    Keywords: Partial filling technique ; Capillary electrophoresis ; On-line micellar electrokinetic capillary chromatography - electro-spray ionization - mass spectrometry ; Corticosteroids ; Mixed micelles ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The one-line combination of micellar electrokinetic chromatography (MECC) with electrospray ionization-mass spectrometry (ESI-MS) was investigated using some corticosteroids as model components. The on-line technique is difficult because the micelles in the electrolyte solution tend to soil the mass spectrometer and lower the sensitivity of the spectrometer. To prevent the micelles from reaching the mass spectrometer, several techniques have been developed among which is the partial filling (PF) technique. In this study the PF-MECC technique was investigated in an on-line MECC-ESI-MS study of mixtures of corticosteroids. Because the compounds are uncharged, partitioning or interaction with micelles is required to achieve separation. Surfactant solutions of sodium dodecyl sulfate (SDS), sodium cholate (SC), and SDS/SC mixtures were used as micellar phase. Good MECC separation was achieved after optimization of the surfactant concentrations and the length of the injected micellar plug. Both hydrodynamic and electrokinetic injections of the micellar solutions were tested. A basic ammonium acetate solution was used as the CE electrolyte solution. The ESI-MS analysis of the compounds was performed in the positive ionization mode, using an acidic sheath liquid. Because of the low MS intensities of the corticosteroids, the peaks were isolated during the MS runs. MS-MS and MS-MS-MS data on the corticosteroids were obtained by off-line injection of the compounds.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191031
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  • 88
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    Electronic Resource
    Use of a Hepta-tyr glycopeptide antibiotic as chiral selector in capillary electrophoresis (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 1742-1751 
    Details
    ISSN: 0173-0835
    Keywords: Antibiotics ; Chiral separations ; Enantiomers ; Drugs ; Herbicides ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A new glycopeptide antibiotic, MDL 63,246 (Hepta-tyr), of the teicoplanin family, has been evaluated in capillary electrophoresis for the resolution of chiral compounds of pharmaceutical and environmental interest. Electrophoretic separations were carried out in a polyacrylamide-coated capillary using the partial filling-counter current mode with aqueous-organic buffers in the pH range 4-6. Experimental parameters affecting resolution, such as antibiotic concentration, buffer pH, organic modifier type and capillary temperature, were studied. The Hepta-tyr antibiotic exhibited a high enantiorecognition capability towards the studied compounds at very low concentrations (1-2 mg/mL). The optimum experimental conditions were achieved by using a buffer at pH 5 containing acetonitrile at 25°C.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191036
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  • 89
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    Electronic Resource
    Identification of maize lines via capillary electrophoresis of zeins in isoelectric, acidic buffers (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 1738-1741 
    Details
    ISSN: 0173-0835
    Keywords: Isoelectric buffers ; Capillary electrophoresis ; Zeins ; Maize ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Modified capillary zone electrophoresis of zeins in strongly acidic, isoelectric buffers is reported for screening of maize (Zea mays L.) lines. The optimized background electrolyte contained 40 mM aspartic acid (pH = pI = 2.77), 8 M urea and 0.5% short-chain hydroxyethylcellulose (Mn 27000 Da) (apparent pH in 8 M urea: 3.9). Due to the low conductivity of such a buffer (0.7 mmhos), separations can be carried out at 800 V/cm, even in relatively large bore capillaries (50 μ ID), ensuring good sensitivity. The zein patterns thus obtained are species-specific and allow easy identification of all maize lines tested. No adsorption of proteins to the silica wall is observed and high reproducibility in peak areas and transit times is obtained. The relatively slow migration time (ca. 30 min), even under such a high voltage gradient, is attributed to the paucity of basic amino acid residues typical of zeins, leading to an unfavorable charge/ mass ratio due to the modest net positive charge at the operative pH.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191035
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  • 90
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    Electronic Resource
    Use of scavenger beads to remove excess labeling reagents from capillary zone electrophoresis samples (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2129-2132 
    Details
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Scavenger beads ; Fluorescence labeling ; Oligosaccharides ; Reagent removal ; Sample preparation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: In many cases, samples for capillary zone electrophoresis (CZE) are derivatized with a chromophore or fluorophore to enhance their detectability. To ensure efficient labeling, a large excess of labeling agent is often used, which leads to the presence of a large peak for unreacted reagent. Here we report that excess reagent can be reacted with “scavenger beads” carrying an appropriate functional group to remove it from the sample solution. We present examples of removal of aminonaphthalene mono-, di-, and trisulfonic acid from mixtures in which they were used to label mono- or oligosaccharides by reductive amination. Aldehyde-containing scavenger beads were made by oxidizing Sephadex G-50 beads with sodium periodate. These were added to the labeling reaction mixtures after the reductive amination of the sugars was complete. Almost complete elimination of the peak from the labeling agent could be achieved.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191215
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  • 91
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    The pH dependence of predictive models relating electrophoretic mobility to peptide chemico-physical properties in capillary zone electrophoresis (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2273-2277 
    Details
    ISSN: 0173-0835
    Keywords: Peptide ; Capillary electrophoresis ; Stokes radius ; Predictive models ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: We applied best fitting procedures to capillary electrophoresis (CE) mobility values, measured at varying acidic pH, of a set of 21 peptides with a molecular mass ranging from about 350 to 1850 Da. This method allowed the contemporary measurements of C-terminus and carboxylic group of the side-chain of aspartic and glutamic acid dissociation constants and of peptide Stokes radius at different protonation stages. Stokes radius was related to peptide molecular mass M at the power of a fractional coefficient, and best correlation was found at pH 2.25, the fractional coefficient being equal to 0.68. This value is close to that proposed by R. E. Offord (Nature 1966, 211, 591-593), who suggested a proportionality between the polymer Stokes radius and M2/3. The coefficient value decreases at higher pH, reaching a value of 0.58 at pH 4.25, corresponding to a mean peptide conformational transition towards more compact structures as a consequence of C-terminus dissociation. The measurement of the dissociation constants of each peptide allowed us to determine the percentage error on peptide charge predictions performed utilizing mean dissociation constants. Even for the charge, the best predictive performance is obtained at the most acidic edge of the range of the pH studied, mainly at pH 2.25. Conclusively, this study shows that the best performance of predictive models for peptide CE mobility is obtainable in the very acidic pH range (2.25-2.50) and in the absence of electroosmotic flow, and that a satisfactory predictive equation of peptide electrophoretic mobility (m2V-1S-1) is given by μ = 85.4(Z/M0.68)10-8.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191304
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  • 92
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    Electronic Resource
    Chemiluminescence detection in integrated post-separation reactors for microchip-based capillary electrophoresis and affinity electrophoresis (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2301-2307 
    Details
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Microfluidics ; Immunoassay ; Microchip ; Chemiluminescence ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Chemiluminescence (CL) detection based on the horseradish peroxidase (HRP) catalyzed reaction of luminol with peroxide was investigated as a post-separation detection scheme for microchip-based capillary electrophoresis. An integrated injector, separator and post-separation reactor was fabricated on planar glass wafers. The fluorescein conjugate of HRP (HRP-F1) was used as a sample for optimization of the CL detector response. In devices etched 10 μm deep, with an aluminum mirror integrated onto the backside of the detection zone to enhance collection efficiency, the detection limit, estimated at 3 standard deviations (SD) above background noise, for 1 nL injected sample plugs was 35 nM in HRP-F1. In devices etched 40 μm deep, 8 nL plugs gave a detection limit of 7 nM. Separation and CL detection of the products of an immunological reaction of a F(ab')2 fragment of the HRP conjugate of goat anti-mouse immunoglobulin G (IgG) with mouse IgG was performed on-chip. A linear calibration curve was obtained for the decrease in peak height of the HRP conjugate (53 μg/mL) with increasing mouse IgG (0-60 μg/mL). When microperoxidase was used as an internal standard, the R2 value of a linear least-squares fit was 0.9867, and the relative errors in the slope and intercept were ± 5.8 and ± 1.3%, respectively.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191309
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  • 93
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    Electronic Resource
    Pressure-assisted and pressure-programmed capillary electrophoresis/electrospray ionization time of flight - mass spectrometry for the analysis of peptide mixtures (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2200-2206 
    Details
    ISSN: 0173-0835
    Keywords: Peptide mixtures ; Pressure programming ; Capillary electrophoresis ; Electrospray ionization ; Mass spectrometry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Pressure assisting and pressure programming the inlet of the capillary electrophoresis instrument were used for the analysis of peptide mixtures and protein digests using capillary electrophoresis/electrospray ionization - mass spectrometry (CE/ESI-MS). CE/ESI-MS of peptide mixtures and tryptic digests of proteins was studied using three different types of capillary columns: (i) a freshly aminopropylsilane (APS)-treated column, (ii) an untreated column, and (iii) a degraded APS-treated column. To maintain a constant and adequate buffer flow toward the CE capillary outlet for stable CE and ESI operation, low pressure was applied to the inlet of the CE when an untreated or degraded APS capillary was used. By programming the inlet pressure, CE/ESI-MS analysis time was reduced to 1/3 of its original time. The utility of this technique is demonstrated by CE/ESI-MS analysis of a hemoglobin variant (hemoglobin-S) and its tryptic digests. Identification of the mutant peptide in the tryptic digest of hemoglobin-S was achieved by collision-induced dissociation (CID) of the protein digests using CE/ESI time of flight - mass spectrometry (TOF-MS).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191226
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    Size separation of sodium dodecyl sulfate complexes of human plasma proteins by capillary electrophoresis employing linear polyacrylamide as a sieving polymer (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2308-2316 
    Details
    ISSN: 0173-0835
    Keywords: Sodium dodecyl sulfate electrophoresis ; Capillary electrophoresis ; Protein size separation ; Human plasma proteins ; Linear polyacrylamide ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Electrophoretic conditions to separate sodium dodecyl sulfate (SDS) complexes of human plasma proteins according to their size differences, by capillary electrophoresis employing linear polyacrylamide as a sieving matrix (LPA-CE), have been examined. Using the optimized separation conditions, SDS complexes of human plasma proteins not treated with reducing agents were separated into about 40 peaks and shoulders within 60 min. The molecular mass values of major peaks in a separation pattern were estimated from a plot of molecular mass and migration time for standard proteins and some of the major plasma proteins have been identified on the pattern. The electrophoretic conditions were successfully applied for the analysis of proteins in immunoglo-bulin G (IgG) myeloma sera.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191310
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  • 95
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    A survey of methodological challenges for glycosaminoglycan/proteoglycan analysis and structural characterization by capillary electrophoresis (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2561-2571 
    Details
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Glycosaminoglycans ; Proteoglycans ; Review ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Proteoglycans participate and regulate several physiological processes via their glycosaminoglycan constituents. For a deeper understanding of how they interact with extracellular ligands as well as with cell bound effector molecules, the fine chemical structures of their glycosaminoglycan chains must be elucidated. Lately developed capillary electrophoretic techniques is a powerful analytical tool for the analysis of glycosaminoglycans, combining a high resolving power with sensitive detection. In this review we describe how depolymerized and intact glycosaminoglycans/proteoglycans can be characterized by capillary electrophoresis, relating these analyses to their possible biological significance. Conditions for running these separations and the detection systems for particular applications are also summarized.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191504
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  • 96
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    Analysis of starch structure using fluorophore-assisted carbohydrate electrophoresis (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2603-2611 
    Details
    ISSN: 0173-0835
    Keywords: Starch ; Capillary electrophoresis ; Oligosaccharide ; Fluorophore-assisted carbohydrate electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The analysis of the fine structure of starches is important to the investigation of linkages between starch structure and function and to the investigation of the properties and roles of starch biosynthetic, modifying and degradation enzymes. Fluorophore-assisted carbohydrate electrophoresis has recently been introduced as a method for the analysis of the oligosaccharide populations released by the enzymatic digestion of starches, which has advantages in resolution and sensitivity over previously used methods, and provides the capacity for the facile analysis of oligosaccharide populations on either a molar or mass basis. The use of fluorophore-assisted carbohydrate electrophoresis for the analysis of oligosaccharides is reviewed with particular reference to the choice of label, efficiency of labeling and separation techniques. Examples of separations using slab gel electrophoresis, DNA sequencer analysis and capillary electrophoresis are presented and we conclude that on the basis of resolution and reproducibility, capillary electrophoresis is the method of choice for the separation of oligosaccharides of degree of polymerization from 1 to 100. Examples of isoamylase-debranched starches and glycogens analyzed by capillary electrophoresis are presented. The capillary electrophoresis analysis of starch structure through the analysis of oligosaccharides released by the debranching of limit dextrins derived from starches and glycogens is introduced as a useful diagnostic of starch structure. The potential for future development of novel diagnostics for starch structure using fluorophore-assisted carbohydrate electrophoresis is discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191507
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  • 97
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    Enhancement of sample loadings for the analysis of oligosaccharides isolated from Pseudomonas aeruginosa using transient isotachophoresis and capillary zone electrophoresis - electrospray - mass spectrometry (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2665-2676 
    Details
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Electrospray ; Mass spectrometry ; Oligosaccharides ; Pathogenic bacteria ; Pseudomonas aeruginosa ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The analysis of underivatized core oligosaccharides arising from mild acid hydrolysis of lipopolysaccharides from Pseudomonas aeruginosa serotype O5 was achieved using a transient isotachophoretic preconcentration method coupled to capillary zone electrophoresis-electrospray-mass spectrometry (tCITP-CZE-ES-MS). The combination of a tCITP preconcentration step provided a 10- to 50-fold enhancement of sample loading and a corresponding improvement in sensitivity compared to the conventional zone electrophoresis format. Electrophoretic conditions, enabling the separation of these anionic analytes, were developed to determine possible sites of heterogeneity on either the core or the O-chain structures. The tCITP-CZE-ES-MS technique provided unparalleled resolution of the different core glycoforms and oligosaccharides obtained from the acid cleavage of the native endotoxins whether isolated following conventional gel permeation chromatography or obtained from direct hydrolysis of the bacterial isolates. These investigations also highlighted the highly phosphorylated nature of these complex cell membrane components, where the heptose residues of the core oligosaccharide can bear up to six phosphate groups# NRCC: 42370..
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191516
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  • 98
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    A tabulated review of capillary electrophoresis of carbohydrates (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2539-2560 
    Details
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Simple carbohydrates ; Glycoprotein glycans ; Glycopeptides ; Glycoforms ; Glycolipids ; Glycosaminoglycans ; Review ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: This review summarizes publications on capillary electrophoresis (CE) of carbohydrates, covering almost all hitherto published papers on this topic. It is designed to be a convenient tool for the literature search by providing a comprehensive table. Since CE analysis of carbohydrates is generally complicated due to the structural diversity of carbohydrate species, an attempt is made in this table to supply detailed information on the analyzed form (underivatized or derivatized, type of derivative) and analytical conditions (capillary size, state of the inner wall, composition of the electrophoretic solution, applied voltage, detection method, etc.), for each combination of carbohydrate species to be analyzed. In addition, a brief overview is presented to help in the literature search.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191503
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  • 99
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    Electronic Resource
    Electrophoretic methods for process monitoring and the quality assessment of recombinant glycoproteins (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2572-2594 
    Details
    ISSN: 0173-0835
    Keywords: Electrophoresis ; Capillary electrophoresis ; Proteins ; Glycoproteins ; Recombinant ; Quality control ; Process monitoring ; Glycosylation ; Oligosaccharides ; Glycoforms ; Review ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: In many ways electrophoretic techniques appear ideal for quality monitoring of proteins and are thus well suited for the analysis of recombinant glycoproteins. The requirements of high throughput, comparative analysis and resolution of many variants are met by several electrophoretic techniques. A wide variety of such techniques are available to biotechnologists in the rapidly developing area of recombinant glycoproteins. It is the aim of this review to specifically cover recent work which has been applied to the analysis of DNA-derived glycoproteins, both from a process control standpoint and final product validation. All major areas of electrophoresis including sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), isoelectric focusing and techniques utilizing capillary electrophoresis are covered, with emphasis on analysis of glycoforms and oligosaccharide profiles of recombinant glycoproteins. As illustration, actual examples rather than standard glycoproteins are given to indicate the potential and limitations which may be encountered. It is anticipated that this review will prove a useful and practical guide to the latest developments by indicating the relevant merits of different methods.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191505
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  • 100
    Electronic Resource
    Electronic Resource
    Capillary electrophoretic analysis of ginseng polypeptide (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 1270-1274 
    Details
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Lipolysis ; Magnesium ; Panax ginseng ; Peptide ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A ginseng polypeptide (GPP) found in ginseng roots and its modified peptides were tested by capillary zone electrophoresis (CZE) under acidic as well as basic conditions. Modified peptides were synthesized for three purposes: (i) to analyze their functions in the first three acidic amino acid residues, (ii) to analyze their functions in three sequenced glycines, and (iii) to analyze the length of side chains in acidic amino acids. The roles of glycines, acidic amino acids and amino acid side chains in the binding of Mg2+ were studied at pH values less than 7.0. The migration times of GPP varied with the pH of various electrophoresis buffers, and electrophoresis patterns were significantly changed between pH 7.0-7.5. Based on the electrophoretic analysis, it was concluded that the binding mechanisms for Mg2+ or conformations of GPP changed between low pH and high pH.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190808
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