bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design of Peptides That Form Amyloid‐Like Fibrils Capturing Amyloid β1–42 Peptides
Authors: Sato Junichi , Takahashi Tsuyoshi , Oshima Hideo , Matsumura Sachiko , Mihara Hisakazu 
Published: July 2007

AbstractAmyloid β‐peptide (Aβ) plays a critical role in Alzheimer's disease (AD). The monomeric state of Aβ can self‐assemble into oligomers, protofibrils, and amyloid fibrils. Since the fibrils and soluble oligomers are believed to be responsible for AD, the construction of molecules capable of capturing these species could prove valuable as a means of detecting these potentially toxic species and of providing information pertinent for designing drugs effective against AD. To this aim, we have designed short peptides with various hydrophobicities based on the sequence of Aβ14–23, which is a critical region for amyloid fibril formation. The binding of the designed peptides to Aβ and the amplification of the formation of peptide amyloid‐like fibrils coassembled with Aβ are elucidated. A fluorescence assay utilizing thioflavin T, known to bind specifically to amyloid fibrils, revealed that two designed peptides (LF and VF, with the leucine and valine residues, respectively, in the hydrophobic core region) could form amyloid‐like fibrils effectively by using mature Aβ1–42 fibrils as nuclei. Peptide LF also coassembled with soluble Aβ oligomers into peptide fibrils. Various analyses, including immunostaining with gold nanoparticles, enzyme‐linked immunosorbent assays, and size‐exclusion chromatography, confirmed that the LF and VF peptides formed amyloid‐like fibrils by capturing and incorporating Aβ1–42 aggregates into their peptide fibrils. In this system, small amounts of mature Aβ1–42 fibrils or soluble oligomers could be transformed into peptide fibrils and detected by amplifying the amyloid‐like fibrils with the designed peptides.
Metabolic Syndrome and Cardiovascular Disease: Challenges and Opportunities
Authors: Cooper‐DeHoff, Rhonda M. , Pepine, Carl J. 
Published: July 2007

AbstractMetabolic syndrome (MetS) has been defined in different ways. However, key components common to most definitions are a constellation of risk factors including abdominal adiposity, impaired fasting glucose, hypertension, and dyslipidemia. A major mediator of MetS appears to be insulin resistance, which relates to the development of the vascular and metabolic dysfunctions that precede overt cardiovascular disease and type 2 diabetes. Evidence suggests that the mechanisms underlying the elevated cardiovascular risk associated with MetS begin with subclinical organ damage. Therapy for MetS targets individual components of the syndrome and includes lifestyle interventions, lipid‐modifying therapy, and antihypertensive agents, particularly those that inhibit the renin‐angiotensin system. Results of trials of angiotensin‐converting enzyme inhibitors and angiotensin receptor blockers have demonstrated reductions in new‐onset diabetes and cardiovascular events in a wide range of patients. Clinical trials to investigate further the role of these drugs in the primary prevention of type 2 diabetes in patients with MetS are currently under way. The purpose of this paper is to review the MetS from the perspective of the cardiology workforce with the hope that a better understanding of the links between MetS and cardiovascular disease could lead to improved management of persons at risk. Copyright © 2007 Wiley Periodicals, Inc.
The Andersen thermostat in molecular dynamics
Authors: E Weinan , Li Dong 
Published: July 2007

AbstractWe carry out a mathematical study of the Andersen thermostat [1], which is a frequently used tool in molecular dynamics. After reformulating the continuous‐ and discrete‐time Andersen dynamics, we prove that in both cases the Andersen dynamics is uniformly ergodic. A detailed numerical analysis is presented, establishing the rate of convergence of most commonly used numerical algorithms for the Andersen thermostat. Transport properties such as the diffusion constant are also investigated. It is proved for the Lorentz gas model where there is intrinsic diffusion that the diffusion coefficient calculated using the Andersen thermostat converges to the true diffusion coefficient in the limit of vanishing collision frequency in the Andersen thermostat. © 2007 Wiley Periodicals, Inc.
Diffractive nonlinear geometrical optics for variational wave equations and the Einstein equations
Authors: Alì Giuseppe , Hunter John K. 
Published: July 2007

AbstractWe derive an asymptotic solution of the vacuum Einstein equations that describe the propagation and diffraction of a localized, large‐amplitude, rapidly varying gravitational wave. We compare and contrast the resulting theory of strongly nonlinear geometrical optics for the Einstein equations with nonlinear geometrical optics theories for variational wave equations. © 2007 Wiley Periodicals, Inc.
Distributions for which div v = F has a continuous solution
Authors: De Pauw Thierry , Pfeffer Washek F. 
Published: July 2007

AbstractThe equation div v = F has a continuous weak solution in an open set U ⊂ ℝm if and only if the distribution F satisfies the following condition: the F(φi) converge to 0 for every sequence {φi} of test functions such that the support of each φi is contained in a fixed compact subset of U, and in the L1 norm, {φi} converges to 0 and {∇φi} is bounded. © 2007 Wiley Periodicals, Inc.
Gas‐Phase Infrared Photodissociation Spectroscopy of Tetravanadiumoxo and Oxo–Methoxo Cluster Anions
Authors: Feyel Sandra , Schwarz Helmut , Schröder Detlef , Daniel Charles , Hartl Hans , Döbler Jens , Sauer Joachim , Santambrogio Gabriele , Wöste Ludger , Asmis Knut R. 
Published: July 2007

AbstractThe infrared spectra of the binary vanadium oxide cluster anions V4O9− and V4O10− and of the related methoxo clusters V4O9(OCH3)− and V4O8(OCH3)2− are recorded in the gas phase by photodissociation of the mass‐selected ions using an infrared laser. For the oxide clusters V4O9− and V4O10−, the bands of the terminal vanadyl oxygen atoms, ν(VOt), and of the bridging oxygen atoms, ν(VObV), are identified clearly. The clusters in which one or two of the oxo groups are replaced by methoxo ligands show additional absorptions which are assigned to the CO stretch, ν(CO). Density functional calculations are used as a complement for the experimental studies and the interpretation of the infrared spectra. The results depend in an unusual way on the functional employed (BLYP versus B3LYP), which is due to the presence of both VO(CH3) single and VO double bonds as terminal bonds and to the strong multireference character of the latter.
A neural network for signal decomposition problems
Authors: Forti Mauro 
Published: July 2007

AbstractThis paper presents the design of a neural network for signal decomposition problems with application examples. For this class of problems the proposed network has the same dynamics as the Hopfield net, but it is shown to realize theO(M2) connection paths among theMneurons with a number of wires and conductances increasing onlylinearlywith increasingM, i.e. reducing this number byone dimensionwith respect to thequadraticallyincreasing number of wires and conductances required in the Hopfield net.Other advantages of the proposed neural network are discussed in relation to classical examples of decomposition problems. In particular, a new architecture for anN‐bit A/D converter is presented employing 4Nconductances instead of theN(N + 1) Hopfield A/D conductances.
A remark on the wave‐form relaxation method
Authors: Schneider Klau S. R. 
Published: July 2007

AbstractThe wave‐form relaxation method (WRM) is an essential tool to compute the solution of an initial value problem for a broad class of large systems of differential algebraic equations in a reasonable CPU time. In this paper we give a sufficient condition for the convergence of the WRM which is more suitable for applications than that given by Lelarasmeeet al. At the same time we provide a new, short proof for the convergence of the WRM.
Finding all solutions of piecewise linear functions and application to circuit design
Authors: Leenaerts D. M. W. , Hegt J. A. 
Published: July 2007

AbstractAn algorithm is given for solving a set of underdetermined non‐linear functions where some or all unknown variables are confined within a certain interval. the functions must be described by piecewise linear models with virtually no restriction to the dimension of the functions or models. the algorithm is able to find all separate solution points of equations on well‐posed functions and can trace solution spaces, eventually composed of several disjunct branches, without any need for initial points. the presented methodology guarantees to find all solutions within a finite number of steps.In top‐down circuit design, at each level one must solve a set of underdetermined equations in such a way that the solution space, if non‐empty, is in agreement with solutions found earlier in the hierarchy. the presented algorithm can be used in such a hierarchical environment and guarantees to find all solutions at each level which are not in conflict with solutions found at higher levels.
Recursive digital filters which are free from subharmonics
Authors: Werter Michael J. 
Published: July 2007

AbstractIn recursive digital filters, quantization of signals can result in instabilities such as limit cycles and subharmonics. the aim of this paper is to analyse these instabilities in periodically excited recursive digital filters and to present methods to suppress the unwanted phenomena. A new type of digital filter structure is introduced which is free from subharmonics for discrete‐time periodic input signals with a given period N. Using the theory of cyclotomic polynomials, this structure is extended to suppress subharmonics for input signals which are periodic with a divisor of N. A general principle is described to convert a stable, autonomous state space digital filter into one which is free from subharmonics under any periodic excitation with a given period N.
Odd‐degree selective bandpass digital filters interpolating linear phase and constant group delay
Authors: Abo‐Zahhad Mohammed 
Published: July 2007

AbstractA novel simultaneous amplitude and phase approximation method is presented for the construction of non‐minimum phase odd‐degree transfer functions of distributed (or digital) bandpass filters interpolating linear phase and constant group delay at a set of frequencies in the passband. the passband amplitude characteristic is equiripple interpolating exact transmission at the same set of frequencies. In addition, the stopband amplitude characteristic is maximally flat and the filter selectivity is achieved by introducing a number of transmission zeros distributed arbitrarily between zero and infinite frequencies. the resulting transfer functions are always stable for all the cases considered. Typical characteristics for filters of ninth to 15th degree are graphically presented. the transfer functions presented are also capable of realization as distributed microwave, switched‐capacitor, digital or wave‐digital filters.
Hysteresis in electronic circuits: A circuit theorist's perspective
Authors: Kennedy Michael Peter , Chua Leon O. 
Published: July 2007

AbstractIn this exposition we hope to dispel some common misconceptions about the nature of hysteresis elements are associated with parasitic dynamics in the circuit and therefore should not be considered part of the static characteristics.We examine the Schmitt trigger ciruit, which exhibits hysteresis in its transfer characteristic, and study a neuraltype pulse oscillator, one of a class of oscillators which relies for its operation on diriving point hysteresis. We illustrate the concepts of DC characteristics, the dynamic route, the jump phenomenon and parasitic dynamics. We show how a clear understanding of these ciruit theoretic principles leads to better analysis and synthesis methods for hysteretic cirucits.
New Algorithms For Two‐ and Three‐Layer Channel Routin
Authors: Wang Deborah , Kuh Ernest S. 
Published: July 2007

AbstractIn this paper a number of new channel‐routing algorithms are presented. the routing strategy is based on parallel bubble‐sorting and river‐routing techniques. an important concept introduced is the POTENTIAL function, which serves as a measure of the degree of difficulty of a particular channel‐routing problem. Both non‐Manhattan wires and overlapping wires are used.Although the methods are initially derived for two‐layer routing with two‐terminal nets only, extensions to multiterminal nets and three‐layer routing have been made. Preliminary results indicate that in many instances the new algorithm outperforms the traditional approaches.
Parametric yield optimization of CMOS analogue circuits by quadratic statistical circuit performance models
Authors: Yu T. K. , Kang S. M. , Sacks J. , Welch W. J. 
Published: July 2007

AbstractA major bottleneck in the design and parametric yield optimization of CMOS integrated circuits lies in the high cost of the circuit simulations. One method that significantly reduces the simulation cost is to approximate the circuit performances by fitted quadratic models and then use these computationally inexpensive models to optimize the parametric yield. In this paper quadratic statistical circuit performance models are applied to maximize the parametric yield of CMOS analogue circuits. It is found that quadratic polynomials may not always model the circuit performances well. However, with engineering knowledge applied to identify and reduce the causes of the errors, accurate performance models and yield maximization can be achieved with a reasonably small number of circuit simulations, as illustrated through examples. Distinctions between the present method and previous applications of quadratic modelling to statistical circuit design are made.
A Computer‐Aided Design Toolkit For Continuous/Discrete Systems Based On Continued Fractions
Authors: Vakilzadian Hamid , Ismail Mohammed 
Published: July 2007

AbstractThis paper presents new algorithms (1) to generate complete mathematical symbolic expressions of continued fraction expansion coefficients in the s‐domain, (2) to determine their numeric values and (3) to perform continued fraction inversion in the s‐domain. A software package in PASCAL and LISP to implement these algorithms is developed. In addition, a simple z‐domain inversion algorithm used in the computer implementation of bilinear s‐z transformation is also included in the software package. These algorithms play an important role in the analysis and synthesis of complex electrical networks and control systems. Especially, the s‐domain expansion and inversion algorithms have potential applications in model simplification and system order reductions. the paper also shows that the package, as such, serves as a comprehensive computer‐aided analysis and design (CAD) toolkit for both continuous and discrete systems. the software is interactive and runs on computers equipped with a PASCAL or LISP compiler. It is noted that the iterative implementation of these methods using the new continued fraction algorithms saves considerable memory space and processing time. Numerical examples and computer data are given to demonstrate the development of the new algorithms and the usefulness of the software toolkit in the CAD design of continuous and discrete systems.
Global properties of continuous piecewise linear vector fields. Part II: Simplest symmetric case in ℝ2
Authors: Lum Robert , Chua Leon O. 
Published: July 2007

AbstractAmong non‐linear vector fields, the simplest that can be studied are those which are continuous and piecewise linear. Among these non‐linear vector fields a large and important subset are those vector fields which are odd symmetric. Associated with these types of vector fields are partitions of the state space into a finite number of regions. In each region the vector field is linear. On the boundary between regions it is required that the vector field be continuous from both regions in which it is linear. This presentation is devoted to the analysis in two dimensions of the simplest possible types of continuous piecewise linear vector fields with odd symmetry, namely those vector fields possessing a pair of symmetric boundary conditions.As a practical concern the analysis will attempt to ask and answer questions raised about the existence of steady state solutions. Since the local theory of fixed points in a linear vector field is sufficient to determine the stability of fixed points in a piecewise linear vector field, most of the steady state behaviour to be studied will be towards limit cycles. the results will present sufficient conditions for the existence, or non‐existence as the case may be, of limit cycles. Particular attention will be paid to the domain of attraction whenever possible.With these results qualitative statements may be made for piecewise linear models of physical systems which have odd symmetry.
Low‐passband‐sensitivity switched capacitor filters using a parallel connection of two structurally lossless networks
Authors: Gobet Claude‐Alain , Mitra Sanjit K. , Petraglia Antonio 
Published: July 2007

AbstractThe low‐sensitivity property of IIR digital filters designed using a parallel connection of two allpass sections has already been demonstrated in the past few years. This property is closely related to the use of a particular type of allpass structures, calledstructurally losslessnetworks, which remain allpass regardless of the coefficient quantization. In this paper we provide a general theory for the synthesis of low‐passband‐sensitivity switched capacitor (SC) filters using a similar technique. the design of stray‐insensitive structurally allpass SC sections is emphasized, ensuring the passivity property for the overall filter. Design examples are presented with computer simulations and experimental results to compare the performance of the different proposed structures. Analytical sensitivity calculations are also derived yielding useful formulae for the prediction of the filter sensitivities with respect to capacitor ratios, particularly in the stopband.
A unified framework for gradient algorithms used for filter adaptation and neural network training
Authors: Marcos Sylvie , Macchi Odile , Vignat Christophe , Dreyfus Gérard , Personnaz Léon , Roussel‐Ragot Pierre 
Published: July 2007

AbstractIn this paper we present in a unified framework the gradient algorithms employed in the adaptation of linear time filters (TF) and the supervised training of (non‐linear) neural networks (NN). the optimality criteria used to optimize the parametersHof the filter or network are the least squares (LS) and least mean squares (LMS) in both contexts. They respectively minimize the total or the mean squares of the errore(k)between an (output) reference sequenced(k)and the actual system outputy(k)corresponding to the inputX(k). Minimization is performed iteratively by a gradient algorithm. the indexkin (TF) is time and it runs indefinitely. Thus iterations start as soon as reception ofX(k)begins. the recursive algorithm for the adaptationH(k– 1) →H(k)of the parameters is implemented each time a new inputX(k)is observed. When training a (NN) with a finite number of examples, the indexkdenotes the example and it is upper‐bounded. Iterative (block) algorithms wait until allKexamples are received to begin the network updating. However,Kbeing frequently very large, recursive algorithms are also often preferred in (NN) training, but they raise the question of ordering the examplesX(k).Except in the specific case of a transversal filter, there is no general recursive technique for optimizing the LS criterion. However,X(k)is normally a random stationary sequence; thus LS and LMS are equivalent whenkbecomes large. Moreover, the LMS criterion can always be minimized recursively with the help of the stochastic LMS gradient algorithm, which has low computational complexity.In (TF),X(k)is a sliding window of (time) samples, whereas in the supervised training of (NN) with arbitrarily ordered examples,X(k– 1) andX(k)have nothing to do with each other. When this (major) difference is rubbed out by plugging a time signal at the network input, the recursive algorithms recently developed for (NN) training become similar to those of adaptive filtering. In this context the present paper displays the similarities between adaptive cascaded linear filters and trained multilayer networks. It is also shown that there is a close similarity between adaptive recursive filters and neural networks including feedback loops.The classical filtering approach is to evaluate the gradient by ‘forward propagation’, whereas the most popular (NN) training method uses a gradient backward propagation method. We show that when a linear (TF) problem is implemented by an (NN), the two approaches are equivalent. However, the backward method can be used for more general (non‐linear) filtering problems. Conversely, new insights can be drawn in the (NN) context by the use of a gradient forward computation.The advantage of the (NN) framework, and in particular of the gradient backward propagation approach, is evidently to have a much larger spectrum of applications than (TF), since (i) the inputs are arbitrary and (ii) the (NN) can perform non‐linear (TF).
A fast, single‐layer, area router for semi‐custom analogue circuits
Authors: Buset Oscar , Declercq Michel , Rahali Fouad , Vaucher Pascal 
Published: July 2007

AbstractThis paper describes the router developed for ALPS, the analogue layout prototyping system. the ALPS router employs some classic techniques and contributes a new, fast implementation of a maze‐running algorithm and a new algorithm for finding two disjoint paths in a graph (the so‐called ‘two path problem’). Discussion of these points is coupled with a review of existing routing algorithms and techniques, and comparisons where possible.
Design criteria for high‐frequencyRC‐active sinusoidal oscillators
Authors: Carlosena Alfonso , Martinez Pedro A. , Porta Sonia 
Published: July 2007

AbstractHigh‐frequencyRC‐active sinusoidal oscillators using two op amps are surveyed from a unified viewpoint. Information about their performance is obtained using linear and non‐linear approaches. As a consequence of this analysis, two main criteria are proposed to optimize these systems and to select the best configuration for a given application. the first criterion is related to the feasibility of obtaining an oscillation frequency independent of the op amps used in the design. the second criterion is connected with the level of harmonic distortion present in the signal. Experimental measurements obtained agree closely with the theoretical analysis carried out.
Cellular neural network design for solving specific image‐processing problems
Authors: Śalot Krzysztof 
Published: July 2007

AbstractThis paper is concerned with determining simple CNN‐paradigm‐based circuits for solving specific binary image‐processing problems. Single‐layer CNN templates for performing specified shape extraction, extraction of shapes which contain a desired feature and modified feature detection are derived using a formulated design strategy. the concept of CNNs composed of modified cells is developed and circuits designed for realizing simultaneous detection of distinct features and for extracting horizontal line midpoints are presented.