bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cyclosporin A as a model antigen: immunochemical and structural studies
Authors: Altschuh Danièle 
Published: November 2002

AbstractThe immunosuppressant drug cyclosporin (Cs) A is a cyclic undecapeptide which has been used as a model antigen because structural information and a large number of analogs, modified at each of its 11 positions, were available. This review summarizes immunochemical and crystallographic studies of the interaction between the Fab of monoclonal antibody R45‐45‐11 and Cs. Three points are discussed: (1) the different conformations of CsA and the question of its biologically active form; (2) the Fab–CsA recognition mechanism; and (3) the relationship between structure and binding properties of CsA analogs. Copyright © 2002 John Wiley & Sons, Ltd.
Structural and functional comparisons between vanadium haloperoxidase and acid phosphatase enzymes
Authors: Littlechild Jennifer , Garcia‐Rodriguez Esther , Dalby Andrew , Isupov Misha 
Published: November 2002

AbstractThe crystallographic structures of both the vanadium chloroperoxidase and bromoperoxidase enzymes have been determined with either vanadium or phosphate bound at their active site. The amino acids that are involved in phosphate binding in the acid phosphatase enzymes and those that are coordinated to vanadium in the haloperoxidases appear to be conserved between the two classes of enzyme. The detailed active site architecture for enzymes that recognize and use either vanadium or phosphate will be discussed in relation to their proposed enzymatic mechanism. Copyright © 2002 John Wiley & Sons, Ltd.
A novel compact meandering stripline balun for balanced amplifiers with Bluetooth application
Authors: Lee Shu‐Chuen , Tsang Kim‐Fung 
Published: November 2002

AbstractA novel compact meandering stripline balun for Bluetooth (2.4 GHz) application is reported. The proposed balun is an integral part of the printed circuit board (PCB). Such design reduces the cost and the manufacturing complexity. Analysis using Microwave Office showed that return loss was better than 15 dB and insertion loss was less than 0.6 dB for the full Bluetooth bandwidth. An integrated push–pull power amplifier (PA) of a Bluetooth transceiver that incorporates the balun at its output was designed and implemented. Measurement showed that the average output power of the PA using meandering stripline balun among the 79 channels was −0.86 dBm with a 2‐dB imbalance. Thus, performance was adequate for Bluetooth application and the design was feasible. In addition, a size reduction of 65% was obtained when compared to a half‐wavelength balun. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 423–425, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10627
A comparative study of light scattering from liquid crystal droplets
Authors: Kriezis Emmanouil E. 
Published: November 2002

AbstractLight scattering from electrically small nematic liquid crystal droplets is routinely studied by methods based on the Rayleigh–Gans (RG) approximation. The error introduced by the Rayleigh–Gans approximation is critically assessed for radial, bipolar, and aligned spherical droplets. Comparisons are made with respect to the prediction of the finite‐difference time‐domain (FDTD) method for the above droplet configurations. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 437–441, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10632
A neural network approach to real‐time dielectric characterization of materials
Authors: Olmi R. , Pelosi G. , Riminesi C. , Tedesco M. 
Published: November 2002

AbstractArtificial neural networks (ANNs) are proposed as an inversion approach in microwave measurement methods of the dielectric characteristics of materials. Reflection and transmission methods require a proper electromagnetic (EM) model of the measurement system, and solutions in terms of the material permittivity are usually in implicit form, requiring an inversion procedure that can be costly in terms of computing time. In such applications, the ANN approach is favorable in that the EM computations are performed during the off‐line training phase of the network. As an example of a real‐world application, the ANN approach is tested on a waveguide method for the measurement of permittivity in the X band for which a working solution is yet available, showing that the parameters of interest (permittivity and thickness of the material under measurement) can be obtained in real‐time with a negligible loss of accuracy. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 463–465, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10639
Systematic elaboration of trial function bases for the study of ridged circular waveguide discontinuities polarizer
Authors: Najid A. , Crampagne R. , Baudrand H. , Boukli‐Hacene N. 
Published: November 2002

AbstractThis paper presents a mixed method for the characterization of ridged circular waveguide discontinuities. The method is based on integral equations in combination with a scalar Green's function and a boundary element method for the calculation an arbitrary ridged circular waveguide's mode spectrum. The modes computed by this technique are used as trial function bases for the characterization of arbitrary ridged circular waveguide discontinuities. An improved variational multimodal formulation is used for the characterization of the step discontinuity. Coupling coefficients are evaluated by post processing of the matrices already used in the modes' determination, and the overall scattering matrix is obtained by cascading the impedance matrix of such a discontinuity. In order to validate this method, screws used in filter design and spectrum polarizer are modeled and the numerical results are verified by excellent agreement with published data. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 478–482, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10643
A bandpass filter using dielectric coaxial resonators with a temperature‐stable stepped‐impedance structure
Authors: Lim Sang‐Kyu , Kim Duck‐Whan , Lee Han‐Young , An Chul 
Published: November 2002

AbstractIn this paper, a bandpass filter using stepped‐impedance coaxial resonators is presented. Each stepped‐impedance resonator (SIR) is composed of ceramic/material to ensure temperature stability of the resonant frequency; one has a positive temperature coefficient of resonant frequency (τf), and the other has a negative τf. A capacitively coupled three‐pole bandpass filter is designed and fabricated to have a center frequency of 915 MHz and a passband bandwidth of 20 MHz. The improved temperature stability of this filter is demonstrated by experimental results. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 508–510, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10651
13C NMR and electron spin resonance analyses of the radical polymerization of diisopropyl itaconate
Authors: Hirano Tomohiro , Furuya Kazuhiro , Seno Makiko , Sato Tsuneyuki 
Published: November 2002

AbstractRadical polymerizations of dialkyl itaconates were performed in benzene at 50 °C. The 13C NMR spectra of the obtained polymers indicated that intramolecular chain‐transfer reaction had taken place more frequently in the polymerizations of itaconates with bulkier ester groups as follows: isopropyl (i‐Pr) > n‐butyl (n‐Bu) ≈ ethyl (Et) > methyl (Me). In addition to the 13C NMR analysis, an electron spin resonance (ESR) analysis was conducted for polymerizations of diisopropyl itaconate, the ESR spectra of which consisted of two kinds of resonances due to the radicals with different conformations. It was assumed that the difference in conformation was attributable to the stereosequences near the propagating chain end because the relative intensity ratios of the resonances varied with the magnitude of the intramolecular chain‐transfer reaction, which was accompanied by a decrease in the syndiotacticity of the obtained poly(diisopropyl itaconate)s. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4513–4522, 2002
Ethylene/1‐octene copolymerization studies with in situ supported metallocene catalysts: Effect of polymerization parameters on the catalyst activity and polymer microstructure
Authors: Li Pi Shan Colin , Soares João B. P. , Penlidis Alexander 
Published: November 2002

AbstractEthylene and 1‐octene copolymerizations were carried out with an in situ supported rac‐[dimethylsilylbis(methylbenzoindenyl)] zirconium dichloride catalyst. In a previous study, it was found that some in situ supported metallocenes produced polyethylene/α‐olefin copolymers with broad and bimodal short chain branching distributions and narrow molecular weight distributions. The ability to produce polyolefins with multimodal microstructural distributions in a single metallocene and a single reactor is attractive for producing polymers with balanced properties with simpler reactor technology. In this study, a factorial experimental design was carried out to examine the effects of the polymerization temperature and ethylene pressure, the presence of hydrogen and an alkylaluminum activator, and the level of the comonomer in the feed on the catalyst activity, short chain branching distribution, and molecular weight distribution of the polymer. The temperature had the most remarkable effect on the polymer microstructure. At high 1‐octene levels, the short chain branching distribution of the copolymer broadened significantly with decreasing temperature. Several factor interactions, including the hydrogen and alkylaluminum concentrations, were also observed, demonstrating the sensitivity of the catalyst to the polymerization conditions. For this catalyst system, the responses to the polymerization conditions are not easily predicted from typical polymerization mechanisms, and several two‐factor interactions seem to play an important role. Given the multiple‐site nature of the catalyst, it has been shown that predicting the polymerization activity and the resulting microstructure of the polymer is a challenging task. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4426–4451, 2002
New fluorinated thermoplastic elastomers. I. The synthesis and thermal characteristics of α,ω‐dihydrosilane hybrid fluorinated polysiloxane precursors
Authors: Andre S. , Guida‐Pietrasanta F. , Rousseau A. , Boutevin B. , Caporiccio G. 
Published: November 2002

AbstractThe synthesis of new α,ω‐dihydrosilane hybrid fluorinated polysiloxanes is described via the polycondensation between a diallyl perfluorinated compound and tetramethyldisiloxane. Control over the size of the oligomers is possible when the reaction is performed in two steps. The length of the polysiloxane chains influences the glass‐transition temperature and the thermal stability of the fluorinated oligomers: the higher the length is, the higher the glass‐transition temperature and the thermal stability are. The synthesized compounds have been characterized with 1H, 19F, and 29Si NMR spectroscopy. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4485–4492, 2002
Facile synthesis of hyperbranched polyimides from A2 + BB′2 monomers
Authors: Liu Ye , Chung Tai‐Shung 
Published: November 2002

AbstractFacile syntheses of hyperbranched polyimides were realized by the polymerization of A2 + BB′2 monomers, 2,2‐bis(3,4‐dicarboxylphenyl) hexafluoropropane dianhydride (6FDA) + 2,4,6‐triaminopyrimidine (TAP), performed by mixing the monomers together in N‐methylpyrrolidone at 17% w/v concentrations with molar ratios of 6FDA:TAP ranging from 1:1 to 2:1. The lower reactivity of 2‐amino as compared with 4‐/6‐amino in TAP, demonstrated by 1H NMR, was probably the main reason for no gelation formed during the polymerization although monomer conversions surpassed the theoretical gel points. Fourier transform infrared spectroscopy and NMR were used to verify the structures of the obtained polymers. 1H NMR analysis indicated the degrees of branching (DB) of the polymers increased from 36 to 83% with the molar ratios of 6FDA:TAP increasing from 1:1 to 2:1. Molecular weights were determined by gel permeation chromatography, and inherent viscosities were measured. Glass‐transition temperature values, determined by differential scanning calorimetry, decreased when DB increased, and thermogravimetric analysis reflected the excellent thermal stability of the obtained hyperbranched polyimides. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4563–4569, 2002
Ab initio investigation of the Young's modulus of polyamide‐6
Authors: Peeters Anik , Van Alsenoy C. , Bartha F. , Bogár F. , Zhang M.‐L. , Van Doren V. 
Published: November 2002

AbstractThe Young's modulus of the α form of polyamide‐6 has been calculated using the supermolecule model. The crystalline polymer was represented by a single‐chain molecule, divided into a head, body, and tail part. The body of the model contains an even number of polyamide‐6 units (4–16 units) and is representative for a polyamide‐6 chain. The periodicity of the system was not explicitly taken into account, but in a few tests the effect of a linear constraint has been evaluated. An n‐butyl and n‐pentyl group have been used as head and tail, respectively. In a number of additional calculations the length of the head and tail has been varied. For all supermolecule models the equilibrium and elongated structures have been optimized using ab initio Hartree–Fock calculations with a 6‐31G** basis set. From the energy values of the optimized structure a Young's modulus of 334 GPa has been extrapolated for both the unconstrained and linearly constrained models. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Advances in channel‐adaptive video streaming
Authors: Girod Bernd , Kalman Mark , Liang Yi J. , Zhang Rui 
Published: November 2002

AbstractDespite the well‐known challenges of variations in throughput, delay, and packet loss over the Internet, video streaming has experienced phenomenal growth, owing to the extensive research in video coding and transmission. In this paper, we review several recent advances for channel‐adaptive video streaming that, we believe, will benefit the design of video streaming systems in the future. Employed in different components of the system, these techniques have the common objective of providing efficient, robust, scalable, and low‐latency streaming video. Firstly, by allowing the client to control the rate at which it consumes data, adaptive media playout can be used to reduce receiver buffering and therefore average latency, and provide limited rate scalability. Secondly, rate‐distortion optimized packet scheduling, a transport technique, provides a flexible framework to determine the best packet to send, given the channel behaviors, the packets' deadlines, their transmission histories, the distortion reduction associated with sending each packet, and the interpacket dependencies. Thirdly, at the source encoder, channel‐adaptive packet‐dependency control can greatly improve the error resilience of streaming video and reduce latency. Finally, we address the specific additional challenges for wireless video streaming. We consider three architectures for wireless video and discuss the utility of the reviewed techniques for each architecture. Copyright © 2002 John Wiley & Sons, Ltd.
The 2002 Econometric Theory Awards
Authors: Phillips Peter C. B. 
Published: November 2002

I am delighted to announce the following Econometric
Theory Awards for 2002.Multa Scripsit: Marcus Chambers, Peter M. Robinson,
Zhijie XiaoPlura Scripsit: Karim M. Abadir, John L. Knight,
Oliver Linton, Seiji Nabeya, Whitney Newey, Jeffrey M. WooldridgePlurima Scripsit: Pentti SaikkonenThere are presently three levels of the Econometric Theory
Award: Multa Scripsit, Plura Scripsit, and Plurima Scripsit. The awards
are made annually using an automated point system based on an author's
cumulative publications in ET. A description of the award system
and a copy of the ET Award Certificate are given in the Vol. 13,
No. 2 issue of ET and may be viewed on the journal's web site
at http://korora.econ.yale.edu/et.htm.
Elimination of Channel-Forming Activity by Insertional Inactivation of thep13Gene inBorrelia burgdorferi
Authors: Östberg Yngve , Pinne Marija , Benz Roland , Rosa Patricia , Bergström Sven 
Published: November 2002

ABSTRACTP13 is a chromosomally encoded 13-kDa integral outer membrane protein of the Lyme disease agent,Borrelia burgdorferi. The aim of this study was to investigate the function of the P13 protein. Here, we inactivated thep13gene by targeted mutagenesis and investigated the porin activities of outer membrane proteins by using lipid bilayer experiments. Channel-forming activity was lost in thep13mutant compared to wild-typeB. burgdorferi, indicating that P13 may function as a porin. We purified native P13 to homogeneity by fast performance liquid chromatography and demonstrated that pure P13 has channel-forming activity with a single-channel conductance in 1 M KCl of 3.5 nS, the same as the porin activity that was lost in thep13mutant. Further characterization of the channel formed by P13 suggested that it is cation selective and voltage independent. In addition, no major physiological effects of the inactivatedp13gene could be detected under normal growth conditions. The inactivation ofp13is the first reported inactivation of a gene encoding an integral outer membrane protein inB. burgdorferi. Here, we describe both genetic and biophysical experiments indicating that P13 inB. burgdorferiis an outer membrane protein with porin activity.
Different Spectra of Stationary-Phase Mutations in Early-Arising versus Late-Arising Mutants of
Pseudomonas putida
: Involvement of the DNA Repair Enzyme MutY and the Stationary-Phase Sigma Factor RpoS
Authors: Saumaa Signe , Tover Andres , Kasak Lagle , Kivisaar Maia 
Published: November 2002

ABSTRACT

Stationary-phase mutations occur in populations of stressed, nongrowing, and slowly growing cells and allow mutant bacteria to overcome growth barriers. Mutational processes in starving cells are different from those occurring in growing bacteria. Here, we present evidence that changes in mutational processes also take place during starvation of bacteria. Our test system for selection of mutants based on creation of functional promoters for the transcriptional activation of the phenol degradation genes
pheBA
in starving
Pseudomonas putida
enables us to study base substitutions (C-to-A or G-to-T transversions), deletions, and insertions. We observed changes in the spectrum of promoter-creating mutations during prolonged starvation of
Pseudomonas putida
on phenol minimal plates. One particular C-to-A transversion was the prevailing mutation in starving cells. However, with increasing time of starvation, the importance of this mutation decreased but the percentage of other types of mutations, such as 2- to 3-bp deletions, increased. The rate of transversions was markedly elevated in the
P. putida
MutY-defective strain. The occurrence of 2- to 3-bp deletions required the stationary-phase sigma factor RpoS, which indicates that some mutagenic pathway is positively controlled by RpoS in
P. putida
.
Analysis of Infection Thread Development Using Gfp- and DsRed-Expressing
Sinorhizobium meliloti
Authors: Gage Daniel J. 
Published: November 2002

ABSTRACT

Sinorhizobium meliloti
growth inside infection threads was monitored after inoculation of alfalfa with red- or green-tagged bacteria. Most threads were populated with single bacterial types. Mixed infections were present but gave mixed nodules less often than expected. These patterns are explained by a model describing bacterial growth during infection.
Evaluación de las actitudes proambientales en trabajadores de grandes organizaciones
Authors: García-Mira Ricardo , Santos Ma Carmen , Gómez-Durán Bernardo , Romay José , Fernández Ma Angeles 
Published: November 2002

Este trabajo se enmarca dentro de un proyecto de investigación que pretende el diseño de un programa de intervención, a través del que se trata de dilucidar el papel de las grandes organizaciones en la integración de actitudes ambientales sostenibles en la vida de cada día. El planteamiento de la investigación surge del reconocimiento de la necesidad de fomentar el cambio en las prácticas y actitudes de las personas hacia el entorno, y en el presente trabajo se informará de los resultados obtenidos en la primera fase, consistentes en la evaluación de las actitudes proambientales y de las dimensiones más relevantes que caracterizan la respuesta ambiental. Mediante un instrumento de cuestionario, se pretende desglosar cada componente implicado en la actitud, de acuerdo con el modelo de Rosenberg y Hovland (1960) y la obtención de la estructura dimensional que caracteriza la respuesta evaluativa de los trabajadores de dos organizaciones públicas. Las dimensiones obtenidas son analizadas por medio de procedimientos multivariados y comentadas en relación con un conjunto de escalas de preocupación medioambiental.
Sobre la definición del conflicto interpersonal: aplicación del cluster analysis al estudio semántico
Authors: Infante Eduardo 
Published: November 2002

Siguiendo las iniciativas de varios autores al definir el conflicto y su naturaleza (Pondy, 1967; Fink, 1968; Thomas, 1992), se analizan 78 definicionessobre conflicto interpersonal halladas en diversas fuentes desde 1933 a 1996. El objetivo es el de esclarecer el concepto de conflicto y su naturaleza. Mediante un cluster analysis, se determinaron los tipos de definiciones existentes en la historia de su literatura. Las categorías incluidas fueron las siguientes: (1) fase de conflicto; (2) base del conflicto; (3) percepción; (4) incompatibilidad; (5) vía de interacción; (6) número de implicados; (7) poder (interpersonal); (8) interdependencia; y (9), naturaleza. Los resultados indican que el conflicto interpersonal es mayoritariamente definido como un proceso-producto de carácter subjetivo-cognitivo que implica percepciones de metas incompatiblespor, al menos, dos individuos. Ninguna otra categoría se mencionó con relevancia. El cluster analysis identificódos grupos de definiciones:positivas (32%) y negativas (68%). La mayoría de las definiciones actuales (posteriores a 1984) se incluyeron más en el segundo grupo. Finalmente, se propone una nueva definición sobre conflicto interpersonal.