bluuebunny/crossref_metadata_2025_split huggingface dataset:
Supported membranes as biofunctional interfaces and smart biosensor platforms
Authors: Tanaka Motomu , Sackmann Erich 
Published: November 2006

AbstractThe design of soft biocompatible and functional interfaces on solids is a challenging interdisciplinary endeavour with great potentials for scientific and biotechnnological applications. By combining modern concepts of genetic engineering and bio‐organic chemistry, novel classes of recombinant proteins enable the immobilization of functional nano‐machineries on solid surfaces, which can even beat functions of native biological systems. Mimetics of tissues can be fabricated by deposition of ultrathin films of biopolymers (such as cellulose or hyaluronic acid), which opens new possibilities for fundamental studies of mechanisms of cell adhesion and tissue growth. Careful adjustment of interfacial potentials using such soft interlayers can also realize the stress‐free immobilization of cells for application as monitors of toxic substances and drugs. Planar models of cell surfaces can be fabricated by self‐assembly of membranes on solid substrates functionalized with soft polymers, which play the generic role of cytoskeleton and glycocalix. Planar geometry enables the application of various surface sensitive techniques to study structures and dynamics of biological membranes. This review presents a survey of recent development in supported membranes, and presents some potential application of this concept in smart biosensors. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ohmic contacts for GaAs based nanocolumns
Authors: Wensorra J. , Lepsa M. I. , Indlekofer K. M. , Förster A. , Jaschinsky P. , Voigtländer B. , Pirug G. , Lüth H. 
Published: November 2006

AbstractNonalloyed ohmic contacts with lateral dimensions in the sub‐100 nm range have been processed and characterized. The contacts are suitable for the fabrication of GaAs/AlGaAs nanocolumns designed in a ‘top down’ approach. They are realized on n‐type GaAs using a thin low‐temperature grown GaAs cap layer and Ti/Au metallization. For the lateral patterning of the nanoscaled ohmic contacts, electron‐beam lithography based on Hydrogen Silsesquioxan (HSQ) negative resist is used, followed by sputtering and plasma etching of the metals. The I –V characteristics show ohmic contact behavior and demonstrate the scaling of the proposed contacts down to 50 nm lateral dimension. The specific contact resistance is situated in the range of 1–2 × 10–5 Ω cm2. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Direct biofunctionalization of semiconductors: A survey
Authors: Stutzmann Martin , Garrido Jose Antonio , Eickhoff Martin , Brandt Martin S. 
Published: November 2006

AbstractThe covalent attachment of small organic molecules and larger functional biomolecules such as DNA, enzymes, or other proteins on semiconductors is a new field of basic research with a pronounced interdisciplinary flavour. The ultimate goal of this endeavour is the creation of novel organic/inorganic heterostructures which can provide a direct link between the complex worlds of biology and digital electronics on a nanometer scale. The purpose of the present survey is to provide an overview over basic physics aspects, preparation methods, as well as possible applications of biofunctionalized semiconductors based on different material systems. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
DNA‐Encoded Chemical Libraries
Authors: Dumelin Christoph E. , Scheuermann Jörg , Melkko Samu , Neri Dario 
Published: November 2006

AbstractConventional libraries of chemical compounds, which are individually screened for binding to pharmaceutical targets, are typically limited by screening costs and logistics to an upper size of few hundred thousand compounds. The use of DNA‐encoded chemical libraries promises to revolutionize the way chemical libraries are screened, allowing the synthesis and selection of libraries of unprecedented size. This article reviews the most recent strategies for the construction and selection of DNA‐encoded chemical libraries.
“Syn&Sort”: A Chip‐based Tool for Combinatorial Synthesis
Authors: Gebinoga Michael , Groß G. Alexander , Albrecht Arne , Lübeck Thomas , Henkel Thomas , Hoffmann Patrick , Klemm Uwe , Schlingloff Gregor , Frank Thomas , Schober Andreas 
Published: November 2006

AbstractIn this paper, we present a new method and process for combinatorial solid phase library synthesis. The new method, we call “Syn&Sort”, combines the advantages of the directed sorting technique with those of miniaturized parallel synthesis. Directed sorting steps were realized by combination of two encoding principles: spatially resolved encoding was used for a carrier chip, bearing 60 solid phase units and an individual barcode‐marker for each carrier. Solid phase supports were made of glass with a magnetic core coated with functionalized polymer support. Sixty synthesis units were arranged on each carrier chip using the magnetic “clip board” principle. No special synthesis equipment is necessary because all carriers can be used in standard laboratory equipment. Syn&Sort was applied for the synthesis of a pentamer‐peptide library. The design and construction of the magnetic synthesis support, carrier chips, and handling device are given. Here, we provide proof of principle of the new Syn&Sort method and introduce it to the scientific and commercial research.
Intramolecular hydrogen bond in the hydroxycyclohexadienyl peroxy radicals
Authors: Huang Mingqiang , Wang Zhenya , Yang Yong , Hao Liqing , Zhao Wenwu , Gao Xiaoming , Fang Li , Zhang Weijun 
Published: November 2006

AbstractThe hydroxycyclohexadienyl peroxy radicals (HOC6H6O2) produced from the reaction of OH‐benzene adduct with O2were studied with density functional theory (DFT) calculations to determine their characteristics. The optimized geometries, vibrational frequencies, and total energies of 2‐hydroxycyclohexadienyl peroxy radical IIsand 4‐hydroxycyclohexadienyl peroxy radical IIIswere calculated at the following theoretical levels, B3LYP/6‐31G(d),B3LYP/6‐311G(d,p),and B3LYP/6‐311+G(d,p).Both were shown to contain a red‐shifted intramolecular hydrogen bond (OH … OH bond). According to atoms‐in‐molecules (AIM) analysis, the intramolecular hydrogen bond in the 2‐hydroxycyclohexadienyl peroxy radical IIsis stronger than that one in 4‐hydroxycyclohexadienyl peroxy radical IIIs, and the former is the most stable conformation among its isomers. Generally speaking, hydrogen bonding in these radicals plays an important role to make them more stable. Based on natural bond orbital (NBO) analysis, the stabilization energy between orbitals is the main factor to produce red‐shifted intramolecular hydrogen bond within these peroxy radicals. The hyperconjugative interactions can promote the transfer of some electron density to the OH antibonding orbital, while the increased electron density in the OH antibonding orbital leads to the elongation of the OH bond and the red shift of the OH stretching frequency. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
A generalized homogeneous domination approach for global stabilization of inherently nonlinear systems via output feedback
Authors: Polendo Jason , Qian Chunjiang 
Published: November 2006

AbstractIn this paper, we introduce a generalized framework for global output feedback stabilization of a class of uncertain,inherentlynonlinear systems of a particularly complex nature since their linearization around the equilibrium is not guaranteed to be either controllable or observable. Based on a new observer/controller construction and ahomogeneous dominationdesign, this framework not only unifies the existing output feedback stabilization results, but also leads to more general results which have been never achieved before, establishing this methodology as a universal tool for the global output feedback stabilization of inherently nonlinear systems. Copyright © 2006 John Wiley & Sons, Ltd.
Distributed multi‐vehicle coordinated controlvialocal information exchange
Authors: Ren Wei , Atkins Ella 
Published: November 2006

AbstractThis paper describes a distributed coordination scheme with local information exchange for multiple vehicle systems. We introduce second‐order consensus protocols that take into account motions of the information states and their derivatives, extending first‐order protocols from the literature. We also derive necessary and sufficient conditions under which consensus can be reached in the context of unidirectional information exchange topologies. This work takes into account the general case where information flow may be unidirectional due to sensors with limited fields of view or vehicles with directed, power‐constrained communication links. Unlike the first‐order case, we show that having a (directed) spanning tree is a necessary rather than a sufficient condition for consensus seeking with second‐order dynamics. This work focuses on a formal analysis of information exchange topologies that permit second‐order consensus. Given its importance to the stability of the coordinated system, an analysis of the consensus term control gains is also presented, specifically the strength of the information states relative to their derivatives. As an illustrative example, consensus protocols are applied to coordinate the movements of multiple mobile robots. Copyright © 2006 John Wiley & Sons, Ltd.
Repeatability of paired counts
Authors: Alexander Neal , Bethony Jeff , Corrêa‐Oliveira Rodrigo , Rodrigues Laura C. , Hotez Peter , Brooker Simon 
Published: November 2006

AbstractThe Bland and Altman technique is widely used to assess the variation between replicates of a method of clinical measurement. It yields the repeatability, i.e. the value within which 95 per cent of repeat measurements lie. The valid use of the technique requires that the variance is constant over the data range. This is not usually the case for counts of items such as CD4 cells or parasites, nor is the log transformation applicable to zero counts. We investigate the properties of generalized differences based on Box–Cox transformations. For an example, in a data set of hookworm eggs counted by the Kato–Katz method, the square root transformation is found to stabilize the variance. We show how to back‐transform the repeatability on the square root scale to the repeatability of the counts themselves, as an increasing function of the square mean root egg count, i.e. the square of the average of square roots. As well as being more easily interpretable, the back‐transformed results highlight the dependence of the repeatability on the sample volume used. Copyright © 2006 John Wiley & Sons, Ltd.
Relative efficiency of unequal versus equal cluster sizes in cluster randomized and multicentre trials
Authors: van Breukelen Gerard J. P. , Candel Math J. J. M. , Berger Martijn P. F. 
Published: November 2006

AbstractCluster randomized and multicentre trials evaluate the effect of a treatment on persons nested within clusters, for instance, patients within clinics or pupils within schools. Optimal sample sizes at the cluster (centre) and person level have been derived under the restrictive assumption of equal sample sizes per cluster. This paper addresses the relative efficiency of unequal versus equal cluster sizes in case of cluster randomization and person randomization within clusters. Starting from maximum likelihood parameter estimation, the relative efficiency is investigated numerically for a range of cluster size distributions. An approximate formula is presented for computing the relative efficiency as a function of the mean and variance of cluster size and the intraclass correlation, which can be used for adjusting the sample size. The accuracy of this formula is checked against the numerical results and found to be quite good. It is concluded that the loss of efficiency due to variation of cluster sizes rarely exceeds 10 per cent and can be compensated by sampling 11 per cent more clusters. Copyright © 2006 John Wiley & Sons, Ltd.
Assessing local influence in principal component analysis with application to haematology study data
Authors: Fung Wing K. , Gu Hong , Xiang Liming , Yau Kelvin K. W. 
Published: November 2006

AbstractIn many medical and health studies, high‐dimensional data are often encountered. Principal component analysis (PCA) is a commonly used technique to reduce such data to a few components that includes most of the information provided by the original data. However, PCA is known to be very sensitive to some abnormal observations. Therefore, it is essential to assess such sensitivity in PCA. In this paper, the assessments of local influence based on generalized influence function are developed under the case‐weights and additive perturbation schemes, along with a discussion of the perturbation scheme and the generalized influence function approach. When perturbing different variables of the data, it is noted that the directions of the largest joint local influence for the eigenvalues are all the same. Moreover, these directions are completely determined by the score values of the observations, to which an approximate cut‐off point is given. The proposed methods are applied to analyse a set of haematology study data for illustration. Results add new insights in finding influential observations in the studied data set. Copyright © 2006 John Wiley & Sons, Ltd.
Wind turbine concept market penetration over 10 years (1995–2004)
Authors: Hansen Anca D. , Hansen Lars H. 
Published: November 2006

AbstractThe aim of this article is to investigate the market penetration and share of different wind turbine concepts during the years 1995–2004, a period that represents the maturational era of the modern wind power industry. A detailed overview is given based on suppliers' market data and concept evaluation for each individual wind turbine type sold by the Top Ten suppliers over the selected decade. The investigation is processing information on approximately 160 wind turbine types from 22 different manufacturers that have featured in the Top Ten list of wind turbine suppliers during 1995–2004. The analysis is based on comprehensive data covering approximately 97% of the cumulative wind power installed worldwide at the end of 2004. The article also provides an overall perspective on contemporary wind turbine concepts, classified with respect to both their speed control ability and power control type. Current and future trends for wind turbine concepts are discussed. Copyright © 2006 John Wiley &Sons, Ltd.
Nonlinear time‐series modeling of vole population fluctuations
Authors: Turchin Peter 
Published: November 2006

AbstractA central goal of population ecology is to understand and predict fluctuations in population numbers. Until recently, much of the debate focused on the issue of population regulation by density‐dependent factors. In this paper, I describe an approach to nonlinear modeling of time‐series data that is designed to go beyond this question by investigating the possibility of complex population dynamics, characterized by lags in regulation and periodic or chaotic oscillations. The questions motivating this approach are: what are relative contributions of endogenous vs. exogenous components of dynamics? Is the irregular component in fluctuations entirely due to exogenous noise, or do nonlinearities contribute to it, too? I describe the philosophy and the technical details of the nonlinear modeling approach, and then apply it to a collection of time‐series data on vole population fluctuations in northern Europe. The results suggest that population dynamics of European voles undergo a latitudinal shift from stability to chaos. Dynamics in northern Fennoscandia are characterized by positive Lyapunov exponent estimates, and a high degree of short‐term (one year ahead) predictability, suggesting a strong endogenous component. In more southerly populations estimated Lyapunov exponents are negative, and there is no one‐step ahead predictability, suggesting that fluctuations are driven by exogenous factors.
Analyses of spatial patterns and population processes of clonal plants
Authors: Harada Yuko , Iwasa Yoh 
Published: November 2006

AbstractThe nonrandom spatial structure of terrestrial plants is formed by ecological interactions and reproduction with a limited dispersal range, and in turn this may strongly affect population dynamics and population genetics. The traditional method of modelling in population ecology is either to neglect spatial pattern (e.g. in transition matrix models) or to do straightforward computer simulation. We review here three analytical mothods to deal with plant populations in a lattice‐structured habitat, which propagate both by seeds that scatter over the whole habitat and by vegetative reproduction (producing runners, rhizomes, etc.) to neighboring vacant sites. [1]Dynamics of global and local densities: Dynamical equations of population density considering nearest‐neighbor correlation (spatial clumping) are developed as the joint dynamics of global average density and local density (comparable to mean crowding) based onpair approximation. If there is a linear trade‐off between seed production and vegetative reproduction, the equilibrium abundance of the population may be maximized by engaging both means of reproduction. This result is accurately predicted by the pair approximation method, but not by mean‐field approximation (neglect of spatial structure). [2]Cluster size distributions: Using global and local densities obtained by pair approximation, we predicted cluster size distribution, i.e. the number of clusters of occupied sites of various sizes. [3]Clonal identity probability decreasing with distance: Multi‐locus measurement of allozymes or other neutral molecular markers tells us whether or not a given pair of individuals belong to the same clone. From the pattern of clonal identity probability decreasing with the distance between ramets, we can estimate the relative importance of two modes of reproduction: vegetative propagation and sexual seed production.
Bacteria—A link among ecosystem constituents
Authors: Kato K. 
Published: November 2006

AbstractMicrobial ecology has undergone a revolution over the past two decades due to the numerous innovations in techniques, allowing bacteria to be detected more accurately by direct means. Thus, bacterial life can be distinguished in situ by direct counting under epifluorescence microscopy; automatically counting and sizing by image analyzer equipped with epifluorescence microscopy or by use of flow cytometry; specific radioisotope techniques; and molecular techniques to detect specific taxa. All of these approaches do not require cultivation, which provides a biased view of bacterial communities in nature. Bacteria are abundant in aquatic environments and play important roles as links between dissolved nutrients and the grazers in the food web. The new techniques allow an evaluation of bacterial population dynamics and function in relation to other organisms of higher trophic levels. This mini review aims to show briefly the state‐of‐the‐art in microbial ecology for ecologists concerned with organisms other than microbes, in order to develop further intensive study together with microbial ecologists.
Populations and infectious diseases: Dynamics and evolution
Authors: Kakehashi Masayuki 
Published: November 2006

AbstractThe host‐parasite or host‐pathogen system was analyzed from dynamical and evolutionary viewpoints using simple mathematical models incorporating vertical transmission, immunity and its loss. We first analyzed a model without density regulation of host population. In the analysis on dynamics, the condition for the pathogen to work as a density regulating factor was obtained. In the analysis on evolution, criteria for the evolution of host and pathogen were proposed. These criteria implies that the evolution of hosts should result in an increase in infected host density, whereas the evolution of pathogens a decrease in susceptible host density. The direction of evolution at some parameters of host and that of pathogen were examined when the parameters were independently and freely changeable. Among the parameters, only reduction in additional mortality due to infection was the evolutionary trend common to both host and pathogen. In all the other parameters examined, trend of evolution predicted in host is reversed in pathogen. We then analyzed whether the obtained criteria still hold in models with density regulation of hosts. Using randomly generated parameter sets, we obtained the result that the criteria should hold very likely though they do not always hold. We discussed evolution of virulence when there is a constraint between the traits.
Evolution of mutualistic symbiosis: A differential equation model
Authors: Yamamura Norio 
Published: November 2006

AbstractIn geological history, rapid speciation, called adaptive radiation, has occurred repeatedly. The origins of such newly developing taxa often evolved from the symbiosis of different species. Mutualistic symbioses are generally considered to evolve from parasitic relationships. As well as the previous model of host population with discrete generations, a differential equation model of host population with overlapping generations shows that vertical transmission, defined as the direct transfer of infection from a parent host to its progeny, is an important factor which can stimulate reduction of parasite virulence. Evolution of the vertical transmission rate from both points of view, the parasite and the host, is analyzed. There is a critical level of the rate, below which an evolutionary conflict arises (the parasite would want an increase in the rate while the host would not), and above which both species would correspond to increase the rate. Therefore, once the parasite dominates the evolutionary race so as to overcome this critical level, one‐way evolution begins toward a highly mutualistic relationship with a high vertical transmission rate, possibly creating a new organism through symbiosis with perfect vertical transmission. Changes in other parameters may decrease the critical level, initiating one‐way evolution. However, changes in traits, probably developed through a long interrelationship in parasitism, do not necessarily induce the evolution of mutualism. Establishment of the ability to make use of metabolic and digestive wastes from the partner certainly facilitates the evolution of mutualism, while improvements in reproductive efficiency of parasites and reduction of negative effects from exploitation in hosts on the contrary disturb mutualism.