bluuebunny/crossref_metadata_2025 huggingface dataset:
An investigation of subliminal embed effect on multiple measures of advertising effectiveness
Authors: Rosen Dennis L. , Singh Surendra N.
Published: July 2007

The effect of subliminal sex and death embeds on attention to advertising, change in attitude, behavioral intention, and day‐after recall of advertising were investigated for two products. Contrary to findings in some previous research, no significant effects were indicated in the current study at any level. A review and comparison to previous research is provided, along with a possible explanation for conflicting research findings in the area.
A reealuation of the attentional inertia concept
Authors: Verbeke Willem
Published: July 2007

Anderson's theory about children's attention behavior during television viewing hypothesizes that attention behavior is affected by (a) positive feedback (the inertia hypothesis), and (b) the degree to which a child understands the television program. During an experiment neither component of Anderson's theory was upheld. It was found that children's attention behavior is patterned and stable over time; children either have short or long attention spans. The implications for advertisers are examined.
Music, music videos, and wear out
Authors: Goldberg Marvin E. , Chattopadhyay Amitava , Gorn Gerald J. , Rosenblatt Jerry
Published: July 2007

Repeated exposure to a music video was found to forestall wear out relative to repetitive exposure to the music only. Susceptibility to wear out in the case of the music video was further reduced by eliminating the closure associated with the story told by the video. The level of positive cognitive responses was posited as a mediator to help explain the observed results. © 1993 John Wiley & Sons, Inc.
Parenthood and wildland recreation consumption: An unexplored phenomenon
Authors: Miles Morgan P. , Good David J. , McDonald Barbara , Schultz Roberta J. , Capella Louis M.
Published: July 2007

The effects of parenthood on consumer decision making have not been systematically studied in prior research of the wildland recreation phenomenon. The present study utilizes data from the most recent National Survey of Recreation to assess the direct effects of parenthood on wilderness‐related or wildland outdoor recreation behavior. Additionally, a framework for the conceptualization of the interrelationship between human values, demographics, attitudes toward the environment, wildland management policy variables, attitudes toward wildland recreation, and wildland recreation consumption is proposed. The findings suggest that parenthood is an important variable in understanding wildland outdoor recreation consumption. © 1993 John Wiley & Sons, Inc.
Consumer socialization of preschoolers and kindergartners as related to clothing consumption
Authors: Haynes Janice L. , Burts Diane C. , Dukes Alice , Cloud Rinn
Published: July 2007

This study investigated the clothing selections for purchase of preschool and kindergarten‐aged children in a midsized southern city. The theory of consumer socialization provided framework for the study. Seven hundred questionnaires were distributed to parents/ guardians of 3‐, 4‐, 5‐, and 6‐year‐old children at public and private schools and preschools. A total of 314 usable questionnaires were completed by mothers, yielding a 45% response rate. T tests, ANOVA, and frequencies were used to analyze data. The effects of demographic variables were investigated in relation to three consumer socialization constructs. Findings indicated that consumer socialization of children begins at an early age and is related to selected demographic characteristics. Results of this study are important for those involved in the children's wear business, as well as for clothing and retailing educators. © 1993 John Wiley & Sons, Inc.
Toward a better understanding of the role of advertising message involvement in ad processing
Authors: Laczniak Russell N. , Muehling Darrel D.
Published: July 2007

This study investigates the effect of advertising message involvement (AMI) on brand‐related beliefs, attitude toward the ad (Aad), and their corresponding certainty dimensions. Support is found for the notion that belief strength is unaffected by involvement level, though brand‐related beliefs are held with greater certainty for high‐ as compared to low‐involvement individuals. Aad was also found to be more confidently held for high‐ versus low‐AMI receivers. However, contrary to expectations, AMI had a direct effect on Aad as well. © 1993 John Wiley & Sons, Inc.
Acculturation and advertising communication strategies: A cross‐cultural study of Chinese and Americans
Authors: Lee Wei‐Na
Published: July 2007

The development of a world economy produces more and more marketing efforts that cross cultural boundaries. Sometimes these boundaries are a function of nationality; other times they are defined by culture in a broader sense. In any case, marketers and advertisers are becoming increasingly aware of the need to be culturally conscious in their efforts to communicate with people of various cultural origins. Effective communication depends, to a large extent, on the understanding of the dynamics of culture. Acculturation therefore describes the changes in attitudes, values, and behaviors of members of one cultural group toward the norms of the other cultural group. This article examines the relationship between levels of acculturation and consumer attitudes toward advertising‐related variables in a cross‐cultural empirical study. Based on the discussion of acculturation and empirical results, useful managerial implications are also provided. © 1993 John Wiley & Sons, Inc.
Variations on the pursuit of beauty: Toward a corporal theory of the body
Authors: Domzal Teresa J. , Kernan Jerome B.
Published: July 2007

Departing from the tradition in physical‐attractiveness research, this article proposes an a priori taxonomy of body types that distinguishes people according to how they experience their own corporality. Consumers are shown to differ in how their bodies constitute a sense of self and this conception in turn leads to characteristic modes of body deployment. Depending on how people regard their bodies, their pursuit of beauty varies considerably and these differences have a significant effect on consumers' reactions to attractiveness‐based products and services. © John Wiley & Sons, Ltd.
Women's makeup careers: An interpretive study of color cosmetic use and “Face Value”
Authors: Fabricant Stacey M. , Gould Stephen J.
Published: July 2007

This article reports on an interpretive study of women's use of makeup in which various aspects and dimensions of women's makeup careers are examined. The primary aspects considered include trajectories of experience, the predominant ways or styles of makeup use that are reflected in a typology of individual differences, and identity construction and reflection. The varying perspectives of women with respect to women's roles as associated with makeup use are also discussed, and research implications are offered. © 1993 John Wiley & Sons, Inc.
Evaluation strategies of American and Thai consumers
Authors: Alden Dana L. , Stayman Douglas M. , Hoyer Wayne D.
Published: July 2007

The effects of two factors (congruity of product information with consumer expectations and perceived risk associated with the product) on strategies used by consumers to evaluate products are tested in the United States and Thailand. When product information does not match expectations, consumers in both cultures increase evaluation effort and shift from using summary representations stored in memory to evaluation based on actual product attributes. Perceived risk also enhances evaluation effort in both cultures, but does not result in a similar shift from category‐based to attribute‐based processing. © 1994 John Wiley & Sons, Inc.
Hierarchical heuristics in evaluation of competitive brands based on multiple cues
Authors: Prabhaker Paul R. , Sauer Paul
Published: July 2007

The primary focus of this research is to develop a conceptual framework for analyzing the process by which consumers evaluate brand quality based on multiple cues. The representative design nature of this theory provides a strong analytical foundation for comparing the use of hierarchical versus nonhierarchical heuristics by consumers in making overall brand evaluations It also enables the modeling of individual differences among consumers in their choice of heuristics to evaluate brands. Results of an illustrative experimental investigation show that hierarchical heuristics are as effective as nonhierarchical, or full‐profile, heuristics. It is also shown that brand evaluation heuristics can be broken down into an intuitive (nonlinear) component and a rule‐bound (linear) component. © 1994 John Wiley & Sons, Inc.
Does consumer knowledge affect consumer responses to advertised reference price claims?
Authors: Frankenberger Kristina D. , Liu Ruiming
Published: July 2007

As expected, internal reference prices (IRPs) and purchase intentions for two product categories (microwave ovens and disposable razors) differed according to whether consumers possessed a high or low level of consumer knowledge about the product in this factorial design experiment. Contrary to theory and expectations, neither internal reference points nor purchase intentions were affected by exposure to comparative price advertisements. Students were used as subjects in a before‐after procedure with approximately two weeks between pre‐ and postmeasures of IRPs and purchase intentions. Postmeasures were taken immediately after exposure to ads containing three levels of advertised reference prices. t tests indicated differences between high and low knowledge group IRP means before ad exposure. However, no ANOVA differences were detected in change in IRP or purchase intention scores after ad exposure. © 1994 John Wiley & Sons, Inc.
Subliminal advertising and the psychology of processing unconscious stimuli: A review of research
Authors: Theus Kathryn T.
Published: July 2007

This article reviews progress to date on research on the effects of subliminal stimulation on subject populations and potential applications to persuasive communications. Three areas of inquiry covered in the literature include psychological, physiological, and behavioral (choice) responses, the last of which is of particular interest to advertising and marketing specialists. The article identifies several fruitful areas for continued research and experimentation, especially in areas of social marketing research. © 1994 John Wiley & Sons, Inc.
Psychological associations with shopping: A moderator variable perspective
Authors: McDonald William J.
Published: July 2007

This article takes a moderator variable perspective on the relationships between two psychological variables: shopper decision‐making styles from the consumer behavior literature and the concept of time perceptions as developed in the psychological literature, and shopping behavior, defined as shopping frequency and time spent shopping. Two hypotheses about potential types of moderation are examined to determine if time perceptions moderate relationships between shopper styles and shopping behavior. The finding show that time perceptions operate as a pure moderator for shopping frequency but as a quasimoderator for time spent shopping. © 1994 John Wiley & Sons, Inc.
The computer‐aided design of microwave matching networks
Authors: Sussman‐Fort Stephen E.
Published: July 2007

Matching networks, as used between the consecutive stages of an amplifier to manage the transfer of power between the complex source impedance, the active devices, and the load, continue to be of importance, particularly in microwave systems. Synthesis techniques for these networks have evolved from the classical theory to novel numerical approaches that yield significant practical advantages. We review here several well‐known design methods, including the classical derivation, sloped‐approximation synthesis, and the real‐frequency technique. Also considered are enhancements and variations of these methods. Furthermore, we describe the iterated analysis approach, which appears to provide the greatest design flexibility, efficiency, and accuracy to date. Examples are given which illustrate the relative merits of some of the more modern computer‐assisted techniques. Finally, we discuss ideas for further research in the area of matching network synthesis.
Synthesis of equivalent circuits for inductive strips in homogeneous finline: W/b = 1
Authors: Knorr Jeffrey B.
Published: July 2007

This article describes a procedure for synthesizing equivalent circuits for inductive strips in homogeneous finline with W/b = 1. Values of strip scattering coefficients predicted by the circuit model are shown to be in excellent agreement with the scattering coefficients predicted by a spectral domain electromagnetic model.
Direct synthesis of distributed lossless networks with application to microwave amplifier design
Authors: Julien N. , Mollier J. C.
Published: July 2007

The Simplified Real‐Frequency Method, initiated by Carlin and Yarman in 1982, has rapidly become the most powerful one among the available numerical methods for solving singleor double‐matching problems. So far it has been applied successfully to the synthesis of multistage microwave amplifiers, but the equalizers contained inductors and capacitors only. This article describes the extension of that technique to the direct synthesis of low‐pass and high‐pass distributed matching networks. The main interest of such an extension is to avoid using equivalences between lumped and distributed elements which are not valid in a wide frequency range. In addition, technological constraints are taken into account earlier in the synthesis. Examples are given of bipolar or field‐effect transistor amplifiers which show that LIMDSYN, our in‐house software, is an efficient tool for linear microwave circuit design with distributed elements.
Analysis of discontinuities in a grounded slab waveguide by combination of finite‐element and boundary‐element methods
Authors: Hirayama Koichi , Koshiba Masanori
Published: July 2007

A combined approach of the finite‐element and boundary‐element methods is formulated for the analysis of arbitrarily shaped discontinuities in a grounded slab waveguide. In this approach, the discontinuity region is divided into two regions. One is a finite region with arbitrary inhomogeneities; the other is a semi‐infinite and homogeneous region. The finite‐element and the boundary‐element methods are applied to the former and the latter regions, respectively, Also, analytical solutions in which both the guided and the radiation modes are taken into account are used for uniform waveguide regions connected to the discontinuity region. To show the validity and usefulness of this approach, computed results are given for several kinds of discontinuities, and some of them are compared with theoretical results previously published. © 1992 John Wiley & Sons, Inc.
An analytical FET model including overshoot and surface effects
Authors: Nevermann P. , Wolff I.
Published: July 2007

A new approach for physical one‐dimensional FET modeling is presented, which is based on an analytical velocity overshoot approximation. As an application, an improved description of short‐channel GaAs‐MESFETs is shown. This simulation is equivalent to the use of a saturation velocity, which depends not only on gate length but also on bias. The presented approach is based on a new criterion subdividing the channel, which may also be used in simulation of other types of FETs. A comparison of the proposed model with experimental data of the DC behavior and numerical results shows the necessity of taking surface effects and substrate currents into account. © 1993 John Wiley & Sons, Inc.
Analysis of strip‐line circuit based on planar circuit model and planar circuit equations (invited review article)
Authors: Hsu Jui‐Pang
Published: July 2007

Strip‐line circuits at relatively higher frequencies can be considered as two‐dimensionally extended circuits rather than one‐dimensional transmission‐line circuits. Hence, the stripline circuit can be modeled as a parallel‐plate planar circuit. In this article, the following topics are reviewed and described based on the results of many researchers: (1) how to model the strip‐line circuit to a parallel‐plate waveguide circuit, which leads to a parallel‐plate planar circuit; (2) how to analyze the strip‐line modeled parallel‐plate waveguide circuit based on planar circuit equations and conventional circuit theory where mode voltage and mode current are properly defined—especially how to construct the circuit equations after dividing the planar circuit into parallel‐plate waveguides and planar junctions, and giving the corresponding the mode characteristic impedance and mode impedance; and (3) the practical analysis of a stub‐type lowpass filter and branch‐line 3‐dB hybrid with the corresponding experimental results. The good agreement between the calculated and measured results demonstrates the validity of the present method of analysis. © 1993 John Wiley & Sons, Inc.
A practical design procedure for circularly polarized printed arrays using high frequency CAE
Authors: Naito Motoyuki , Ito Koichi , Matsuzawa Shin‐Ichiro , Takada Jun‐Ichi
Published: July 2007

A practical design procedure for a circularly polarized printed array antenna composed of strip dipoles and slots (CP‐PASS) is presented. CP‐PASS is a kind of series‐fed array, and the equivalent circuit model of CP‐PASS is simplified to be suitable for a computer‐aided design (CAD) package. Some experimental results of a new strip element excited by a stripline and a 9‐element set CP‐PASS are also presented.
An Efficient Method to Calculate the Sommerfeld Integrals Concerning a Microstrip Antenna in Stratified Media: Extension of Discrete Complex Image Theory without the Optimization Process
Authors: Xiaowen Xu , Shizhi Li
Published: July 2007

Discrete complex image theory (DCIT) without the optimization process is used in the calculation of some Sommerfeld integrals (SI) involved in the problem of a microstrip antenna covered with a layer of medium. By comparison to the results of numerical integration method (NIM), it is proved that this DCIT not only has very high efficiency but also has rather satisfying accuracy so long as the proper spatial quasi‐static images (SQSI) are found. Special effort is made to the extraction of the above‐mentioned SQSI, and the analytic expressions of them are presented for the particular SI discussed here. The computation time of DCIT and that of NIM are compared to each other with microcomputer AFTI486, and the result shows that DCIT is several hundred times faster than NIM in the calculation of SI.
Endotoxemia causes a paradoxical intracellular pH recovery in exercising rat skeletal muscle
Authors: Giannesini Benoît , Izquierdo Marguerite , Dalmasso Christiane , Fur Yann Le , Cozzone Patrick J. , Verleye Marc , Guern Marie‐Emmanuelle Le , Gillardin Jean‐Marie , Bendahan David
Published: July 2007

In resting skeletal muscle, endotoxemia causes disturbances in energy metabolism that could potentially disturb intracellular pH (pHi) during muscular activity. We tested this hypothesis using in situ 31P‐magnetic resonance spectroscopy in contracting rat gastrocnemius muscle. Endotoxemia was induced by injecting rats intraperitoneally at t0 and t0 + 24 h with Klebsiella pneumoniae endotoxin (lipopolysaccharides at 3 mg/kg) or saline vehicle. Muscle function was investigated strictly noninvasively at t0 + 48 h through a transcutaneous electrical stimulation protocol consisting of 5.7 minutes of repeated isometric contraction at 3.3 HZ, and force production was measured with an ergometer. At rest, endotoxin treatment did not affect pHi and adenosine triphosphate concentration, but significantly reduced phosphocreatine and glycogen contents. Endotoxemia produced both a reduction of isometric force production and a marked linear recovery (0.08 ± 0.01 pH unit/min) of pHi during the second part of the stimulation period. This recovery was not due to any phenomenon of fiber inactivation linked to development of muscle fatigue, and was not associated with any change in intracellular proton buffering, net proton efflux from the cell, or proton turnovers through creatine kinase reaction and oxidative phosphorylation. This paradoxical pHi recovery in exercising rat skeletal muscle under endotoxemia is likely due to slowing of glycolytic flux following the reduction in intramuscular glycogen content. These findings may be useful in the follow‐up of septic patients and in the assessment of therapies. Muscle Nerve, 2007
Control of molecular weight in polymerization of vinyl chloride with Cp*Ti(OPh)3/MAO catalyst
Authors: Endo Kiyoshi , Nomaguchi Tsuyoshi , Tsuchiya Yoshikatsu
Published: July 2007

Polymerization of vinyl chloride (VC) with titanium complexes containing Ti‐OPh bond in combination with methylaluminoxane (MAO) catalysts was investigated. Among the titanium complexes examined, Cp*Ti(OPh)3/MAO catalyst (Cp*; pentamethylcyclopentadienyl, Ph; C6H5) gave the highest activity for the polymerization of VC, but the polymerization rate was slow. From the kinetic study on the polymerization of VC with Cp*Ti(OPh)3/MAO catalyst, the relationship between the Mn of the polymer and the polymer yields gave a straight line, and the line passed through the origin. The Mw/Mn values of the polymer gradually decrease as a function of polymer yields, but the Mw/Mn values were somewhat broad. This may be explained by a slow initiation in the polymerization of VC with Cp*Ti(OPh)3/MAO catalyst. The results obtained in this study demonstrate that the molecular weight control of the polymers is possible in the polymerization of VC with the Cp*Ti(OPh)3/MAO catalyst. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3872–3876, 2007
Synthesis of AB‐type block copolymers containing benzoxazole and anthracene groups by ATRP and fluorescent property
Authors: Lu Jian‐Mei , Xu Qing‐Feng , Yuan Xin , Xia Xue‐Wei , Wang Li‐Hua
Published: July 2007

Two functional monomers, methacrylic acid 4‐(2‐benzoxazol)‐benzyl ester (MABE) containing the benzoxazole group and 4‐(2‐(9‐anthryl))‐vinyl‐styrene (AVS) containing the anthracene group were synthesized by rational design. The MABE was polymerized via atom transfer radical polymerization (ATRP) using ethyl 2‐bromoisobutyrate (EBIB) as initiator in CuBr/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) catalyst system; block copolymers poly(MABE‐b‐AVS) was obtained, which was conducted by using poly(MABE) as macro‐initiator, AVS as the second monomer, and CuBr/PMDETA as catalyst. The constitute of two monomers in block copolymers poly(MABE‐b‐AVS) by ATRP could be adjusted, that is the constitute of the benzoxazole group and the anthracene group could be controlled in AB‐type block copolymers. Moreover, the fluorescent properties of homopolymers poly(MABE) and block copolymers poly(MABE‐b‐AVS) were discussed herein. With the excitation at λex = 330 nm, the fluorescent emission spectrum of poly(MABE) solution showed emission at 375 nm corresponding to the benzoxazole‐based part; with the same excitation, the fluorescent emission spectrum of poly(MABE‐b‐AVS) solution showed a broad peek at 330–600 nm when the monomer AVS to the total monomers mole ratio was 0.31, and the fluorescent emission spectrum of poly(MABE‐b‐AVS) in film state only showed one peak at 525 nm corresponding to the anthracene‐based unit that indicated a complete energy transfer from the benzoxazole group to the anthracene group. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3894–3901, 2007
Synthesis and morphology of Fe3O4/polystyrene/poly(isopropylacrylamide‐co‐methyl acrylate acid) magnetic composite latex – 2,2′‐azobis (2‐methylpropionamidine) dihydrochloride as initiator
Authors: Lee Chia‐Fen , Chou Yu‐Hui , Chiu Wen‐Yen
Published: July 2007

In this work, Fe3O4/polystyrene/poly(N‐isopropylacryl amide‐co‐methylacrylate acid) (Fe3O4/PS/P(NIPAAM‐co‐MAA)) magnetic composite latex was synthesized by the method of two stage emulsion polymerization. In this reaction system, 2,2′‐azobis(2‐methyl propionamidine) dihydrochloride (AIBA) was used as initiator to initiate the first stage reaction and second stage reaction. The Fe3O4 particles were prepared by a traditional coprecipitation method. Fe3O4 particles were surface treated by either PAA oligomer or lauric acid to form the stable ferrofluid. The first stage for the synthesis of magnetic composite latex was to synthesize PS in the presence of ferrofluid by soapless emulsion polymerization to form the Fe3O4/PS composite latex particles. Following the first stage of reaction, the second stage of polymerization was carried out by the method of soapless emulsion polymerization with NIPAAM and MAA as monomers and Fe3O4/PS latex as seeds. The magnetic composite particles, Fe3O4/PS/P(NIPAAM‐co‐MAA), were thus obtained. The mechanism of the first stage reaction and second stage reaction were investigated. Moreover, the effects of PAA and lauric acid on the reaction kinetics, morphology, and particle size distribution were studied. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3912–3921, 2007
Exploring pathways to reduce the distribution of active sites in the Ziegler–Natta polymerization of propylene
Authors: Ribour David , Bollack‐Benoit Valérie , Monteil Vincent , Spitz Roger
Published: July 2007

Chemical treatments of classical supported Ziegler–Natta precatalysts were conducted by using additional bulky ligands to attempt to narrow and homogenize the active sites distribution in propylene polymerization. Additions of monodentate ligands such as bis(trimethylsilyl)amide, cyclopentadienyl derivates or triphenylsilanol were seen to slow down the polymerization without modifying the distribute properties of polypropylenes. In the case of multidentate ligands (porphines or biquinolines), in addition to the poisoning of active sites, an extraction of titanium from the catalyst surface is observed. A decrease of both melting point and isotacticity (II%) of polymers using these compounds suggest that the most isospecific titanium sites are first extracted from the MgCl2‐surface. The narrowing of the molecular weight distribution confirms that the highly isospecific sites are the most active sites, producing the higher molecular weight polymers. Moreover, this study shows that the distributed properties of polymers are due to the chemical diversity of the active sites with various steric and electronic environments at the catalyst surface and not to mass transfer limitations. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3941–3948, 2007
Rheumatoid arthritis: appropriate treatment in older people
Authors: McKellar Gayle
Published: July 2007

Our series Prescribing in older people gives practical advice for successful management of the special problems experienced by this patient group. Here, the author considers the partic ular problems that arise when treating rheumatoid arthritis in older people. Copyright © 2007 Wiley Interface Ltd
Quantum diffusion of hydrogen in the B.C.C. transition metals
Authors: Rogan J. , Lagos M.
Published: July 2007

The auxiliary function governing the temperature dependence of the small‐polaron diffusion coefficient D(T) is calculated with improved accuracy for impurities occupying tetrahedral and octahedral interstitial sites in tantalum, niobium, and vanadium. This function depends only on the host crystal and determines the shape of the curve D versus T. The nature of the diffusing species enters as just a scale factor and displacement of the Arrhenius plot of D(T). The calculation considers the real vibrational modes of the host crystals and employ state‐of‐the‐art integration techniques over the Brillouin zone to give highly reliable and accurate results. Tables of use in the interpretation of further experiments are given. As an example of application, the diffusion data of hydrogen in tantalum, available for temperatures in the range 15 K < T < 500 K, are analyzed on the basis of the quantum theory of diffusion and a two‐states model.
A comparison of force constants, mechanical and thermal properties in Hg1−xCdxTe and Hg1−xZnxTe mixed crystals
Authors: Bagot D. , Granger R. , Rolland S.
Published: July 2007

Interatomic force constants are deduced from a fit of infrared reflectivity data of HgCdTe (MCT) and HgZnTe (MZT) mixed crystals using a basic unit model for the description of vibrational modes of low wave vector. This allows, for the first time, a direct comparison of bond strengths between MCT and MZT. The obtained results are consistent with a slight decrease in bond strength when Cd is substituted for Hg in MCT and an increase when Zn replaces Hg in MZT. These results are visualized through the bulk modulus variations with composition in both mixed crystals and are compared to known results on their thermal properties.
Electronic structure calculation of Mg, Si, P, S, and Cl impurities in aluminium
Authors: Thiagarajan M. , Iyakutti K. , Palaniyandi E.
Published: July 2007

A fully self‐consistent calculation using the multiple scattering Xα method is used to study the electronic structure, the relation between charge transfer and electronegativity, the bonding characteristics, and the alloying of Mg with Al. The present investigation indicates that the charge transfer from the host Al atoms to the central impurity atom increases with the increase of electronegativity of impurity atoms. It is found that the bonding is metallic for AlMg and for the other impurities considered it gradually becomes ionic. The alloying of Mg with Al is more favourable than with other impurities. The results are compared with the available experimental and theoretical data.
High‐field magnetoconductivity of double‐quantum‐well systems
Authors: Kleinert P. , Bryskin V. V.
Published: July 2007

The high‐field magnetoconductivity of double‐quantum‐well structures is treated on the basis of a microscopic one‐particle model which includes broadening effects due to disorder, finite temperatures, and a phenomenological inclusion of inelastic scattering processes. The theoretical results are consistent with the experimentally observed suppression of quantum Hall states at odd integer filling factors.
Quantum Beats of Recoil‐Free γ‐Radiation in the Direct and Bragg Diffracted Beam
Authors: Kuhn D. , Jex H. , Kienle A.
Published: July 2007

The interaction of recoil‐free γ‐radiation of a 57Co Mössbauer source with a piezo electrically excited X‐cut quartz crystal is investigated. The experiments are performed in the direct beam and in the diffracted beam of the (1120) Bragg reflection. In both geometries we applied time‐resolved correlation experiments to analyze the γ‐quantum beats due to phonon energy transfers. A consistent theoretical explanation of the quantum beats is proposed.
Surface Plasmons Modified by External Light
Authors: Gerlach E.
Published: July 2007

It is shown that the (non‐retarded) surface plasmon spectrum is modified by external light. This effect should be observable, if k∥︁v/Ω is not too small (k∥︁ wave vector of the surface plasmon parallel to the surface, v drift velocity of the carriers, Ω frequency of the external light). Semiconductors are expected to be good candidates, but also metals for small Ω.
Combined Monte‐Carlo Functional Integral Approach to Rare‐Earth Transition Metal Compounds RT2
Authors: de Oliveira N. A. , Gomes A. A.
Published: July 2007

The functional integral formalism, combined with a Monte‐Carlo calculation for the magnetization of rare‐earth spins, is used to describe the magnetic properties of RT2 compounds. The results of the numerical solution of the coupled self‐consistent equations, involving both itinerant d electrons and localized f spins, are presented and discussed.
Re‐Entrant Ferromagnetism in a Two‐Dimensional Spin‐3/2 Ising Model with Random Nearest‐Neighbour Interactions
Authors: Atri A. El , Saber M.
Published: July 2007

The existence of a re‐entrant ferromagnetic phase seems to be a general characteristic of systems with frustration and disorder even when no spin‐glass phase exists. Using an effective field theory based on the use of a probability distribution that correctly accounts for the single site kinematic relations, a two‐dimensional nearest‐neighbour random interaction spin‐3/2 Ising model is studied in which the interactions are indepcndent random variables distributed according to the following law: P (Jij ) = p δ(Jij − J ) + ( 1 − p) δ (Jij − αJ), where J > 0. In a certain range of negative values of α, re‐entrant phase diagrams are found and the threshold p* at which the critical temperature goes to zero depends on α.
LO‐Phonon Instability in Semiconductors in the Presence of Two Laser Fields Plus DC Strong Magnetic Field
Authors: Fonseca A. L. A. , Nunes O. A. C.
Published: July 2007

Phonon scattering by electrons in a bulk semiconductor in two laser fields in the additional presence of a strong (quantizing) magnetic field is discussed. A kinetic equation for the LO‐phonon population is derived, from which the damping rate is calculated. It is found that longitudinal optical lattice waves may be amplified over a relatively narrow range of plasmon wave numbers in the direction perpendicular to the magnetic field direction. Furthermore, the joint action of the three external fields results in a very large amplification rate, in contrast to the zero magnetic field case.
Pressure Dependence of Positron Annihilation in Si
Authors: Benkabou F. , Dufour J. P. , Soudini B. , Amrane N. , Khelifa B. , Aourag H.
Published: July 2007

The pressure dependence of the electron‐positron and the electron‐electron momentum densities in silicon are studied. The observations that the electron‐positron momentum density increases more rapidly with pressure than the electron‐electron momentum density alone is explained in terms of increased positron penetration into the ion cores. The computational technique used here is based on the independent‐particle model (IPM) coupled with the use of the electron pseudo‐wave functions.
EPR Spectroscopy of Thulium Impurities in ZnS Crystals
Authors: Müller St. , Dziesiaty J.
Published: July 2007

EPR spectroscopy is applied to Tm impurities in ZnS crystals containing Ag, Li, and La codopants. After optical irradiation, Tm2+ resonances are observed and make it possible to separate different interstitial sites occupied by Tm2+, cubic sites without local charge compensation and axially distorted ones with [111]w and [001] symmetry due to charge compensation by neighboured defects. Additionally a light‐insensitive signal could be ascribed to Tm3+ ions, occupying substitutional (Zn)sites, compensated by a negatively charged defect in 〈110〉 directions. From the photoionization spectrum the Tm2+ state is located in the upper half of the band gap.
Solitary Magnon Localization and Two‐Magnon Bound State in Antiferromagnet RbFeCl3
Authors: Liu Wu‐Ming , Zhou Ben‐Lian
Published: July 2007

Introducing the Holstein‐Primakoff transformation, the coherent‐state ansatz, and the time‐dependent variation principle, two partial differential equations of motion from the Hamiltonian are obtained. Employing the method of multiple scales, these equations are reduced to envelope function equations and the amplitude function satisfying a nonlinear Schrödinger equation is found. Using the inverse scattering transformation, single, two, and N solition solutions and the gap soliton are obtained and the solitary excitations in the antiferromagnet RbFeCl3 are investigated.
Magnetooptical Properties of Surface Plasma Waves on Copper, Silver, Gold, and Aluminum
Authors: Haefner P. , Luck E. , Mohler E.
Published: July 2007

Surface plasma waves on Cu, Ag, Au, and Al are excited with HeNe laser light (λ = 632.8 nm) by the prism method in the presence of a magnetic field perpendicular to the plane of incidence. The dip at the surface plasma resonance which is observed in the reflectivity when tuning the angle of incidence shows nonreciprocal behaviour with respect to magnetic field or light propagation reversal. Using an ac magnetic field and lock‐in technique the nonreciprocal changes of the reflectivity can be measured with fields of only 0.2 T. The components of the magnetooptical tensor are determined and discussed in the framework of a Drude model.
Photostimulated Phase Transitions in High‐Tc Superconductors and the Origin of the Superconductivity
Authors: Kityk I. V. , Kolinko M. I.
Published: July 2007

The photostimulated phase transition from the semiconducting to the superconducting phase in YBa2Cu3O7−δ (δ > 0.5) single crystals is revealed. The investigations are performed using the time‐resolved dependences of photoresistivity, photovoltage, and optical second harmonic generation. At the same time the time‐resolved Raman and UV‐visible reflection spectra are monitored. A time delay between the second harmonic generation and photocurrent dependences is found. The intrinsic role of two different mechanisms in the occurrence of the photoinduced phase transition is unambiguously shown. To clarify the main features of this transition it is necessary to account for the specific electron‐phonon interaction together with the existence of the Anderson metal‐insulator transition. The performed band energy calculations show the essential role of photoinduced changes in the Fermi energy level location and the total density of states distribution. The intrinsic role of van Hove singularities in the formation of the superconducting gap is shown.
Pump and Probe Techniques for Spin–Lattice Thermalization Measurements. Thermal Requirements
Authors: Callegaro L. , Puppin E.
Published: July 2007

Pump and probe techniques with ultrafast laser pulses represent a well established tool for the measurements of electron‐electron and electron‐phonon thermalization processes. It is shown that expanding these techniques to magnetic systems for spin‐lattice relaxation measurements requires a careful selection of the thermal characteristics of the samples. More precisely, a simulation of the thermal behavior of thin metal films heated by short laser pulses shows that film thickness and substrate thermal properties are crucial parameters.
A Lattice Dynamics Approach to the Acoustic Waves Emitted during Dislocation Annihilation
Authors: Trochidis A. , Polyzos B.
Published: July 2007

The emission of acoustic waves by annihilating dislocation kink‐antikink pairs during the Frank‐Read source operation is investigated. The proposed approach is based on a Frenkel‐Kontorova model where the rigidity of the substrate is removed to establish the interaction mechanism between a dislocation and transverse lattice vibrations of the substrate. It is shown that this interaction can be described by a D'Alembert wave equation coupled with a sine‐Gordon equation. Within the framework of this model, the emission of sound by annihilating dislocation kinks during the Frank‐Read source operation is considered in detail. The obtained results could be of use in interpreting acoustic emission experimental results during plastic deformation of crystals.
Combined Measurements of Length and Modulus Change and Calculation of Effective Pair Potentials for the Amorphous Alloy Cu64Ti36
Authors: Porscha B. , Neuhäuser H.
Published: July 2007

Simultaneous measurements of the length change and of the change of the eigenfrequency at the same specimen are performed for the metallic glass Cu64Ti36. The length change is preferably connected with a long‐range topological relaxation, while the change of the eigenfrequency preferably gives information on the change of the chemical short‐range order. The correlation between the relaxation effects of the two quantities shows a certain change of slope at a characteristic annealing temperature indicating a transition from preferably chemical to topological rearrangements. Assuming a Lennard‐Jones type potential the powers of the effective pair potential can be calculated from the temperature dependence of the measured quantities. It is also possible to get information on the variation of the powers due to the structural relaxation effect.
Charge‐Density Transfer of H Adsorption on the Si(111) (1 × 1) Surface
Authors: Wu B. R. , Cheng C.
Published: July 2007

The charge‐density transfers from ab initio quantum mechanical calculations for the adsorption of hydrogen atoms on the Si(111) (1 × 1) surface are presented. In the initial stages of the adsorption, the interaction occurs between the hydrogen atom and the surface dangling bond or between the hydrogen atom and the hydrogen overlayer. The interaction has the same characteristics as the initial stages of the hydrogen molecule formation. For the adsorbed systems, the charge‐density transfers exhibit strong ionicity with the adsorbed hydrogen atoms being the more electronegative ones. The hydrogen atoms are negatively charged beneath the Si(111) (1 × 1) surface. This property is retained for the hydrogen atoms in the silicon bulk, no matter whether the system is neutral or charged.
Reference System Approach in the Electron Liquid Theory. IV. Momentum Distribution
Authors: Vavrukh M. , Vavrukh N.
Published: July 2007

The problem of universality and limitation of the local‐field conception in modern theory of many‐particle interacting systems is considered on the example of the calculation of momentum distribution. On the basis of the variational derivative δG(q, v)/δϵk (where G(q, v) is the dynamic local‐field correction function, Ek = h2k2/2m) the momentum distribution in the model of the electron liquid in a wide region of the coupling parameter rs is investigated.
A Unified Total Energy Approach to High‐Temperature Superconductivity and Long‐Range Ordering in Solids
Authors: Mizia J. , Romanowski S. J.
Published: July 2007

A novel approach to the long‐range ordering in solids is proposed in which the total energy is minimized with respect to the long‐range ordering parameter. It is shown that the method, on the one hand, reproduces the classic BCS results for superconductivity, whilst also agreeing with the well established results for the itinerant antiferromagnetism. Implications of the method for electronically driven super‐ conductivity are discussed. It is found that the electron transfer around the Fermi energy promotes super‐ conductivity. This transfer is easier in the soft multi‐orbital systems than in the single‐band system.
Deducing Spin‐Hole Interactions from the Three‐Band Anderson Lattice Model for CuO2‐Layered Superconductors
Authors: Kolley E. , Kolley W. , Tietz R.
Published: July 2007

An effective Hamiltonian for localized Cu spins and mobile O holes is deduced from the three‐band Anderson lattice model ascribed to a single CuO2 layer in high‐Tc superconductors. At large but finite Hubbard repulsion strength U on Cu sites the perturbative approach is given completely up to the fourth order in the Cu(d)‐O(p) hybridization amplitude t. Both the Schrieffer‐Wolff transformation and the projection onto the subspace of singly occupied Cu sites are performed by means of a computational algorithm. The resultant interactions in O(t4) include a Kondo‐like spin‐hole exchange in competition to that in O(t2), the spin‐spin superexchange of the Heisenberg‐type, spin‐spin‐hole, hole‐hole, and spin‐hole‐hole correlations. The spin‐hole‐hole coupling, reflecting p‐hole hopping affected by a Kondo exchange, is due to the direct O‐O transfer tp inherent in the periodic Anderson model. It is shown how in the limit tp = 0 the effective Hamiltonian reduces to that originated from the minimal version of the Emery model.
Magnetic Properties of Thin Films Containing Itinerant Electrons Interacting with Localized Spins
Authors: Urbaniak‐Kucharczyk A.
Published: July 2007

The model of ferromagnetism which can be considered as a generalization of the Heisenberg, Stoner, and modified Zener models is applied to the case of thin magnetic films. Calculations are presented within the frame of a Green function formalism of the magnetization distribution across the layer and the thickness dependence of the Curie temperature. The case of h. c. p. thin films with strong surface anisotropy in the high‐temperature region has been discussed in detail.
Scattering of Light on Small Angles in the Conditions of “Devil's Staircase” Existence within the Incommensurate Phase
Authors: Sveleba S. A. , Kapustianik V. B. , Polovinko I. I. , Krochuk A. , Bublyk M.
Published: July 2007

Investigations of small‐angle light scattering in dependence on the temperature change rate, on the distance from the axis of the incident light beam, on the defectivity of a sample, as well as on the polarization of incident light are carried out in [N(CH3)4]2FeCl4 crystals. It is obtained that the small‐angle light scattering in long‐periodic commensurate regions within an incommensurate phase is connected with the scattering on phasons. The appearance of additional scattering of light in the transition regions is caused by the appearance of the perturbation vector qc. Besides, the intensity I(q) in this region depends on the polarization of the incident light testifying the change of the incommensurability wave vector in this region.
Space‐Charge Polarisation and X‐Ray Diffraction Extinction Reduction in Synthetic and Natural Quartz Crystals
Authors: Sebastian M. T. , Klapper H.
Published: July 2007

An X‐ray diffraction study of α‐quartz crystals with in situ electric field along the different crystallographic axes shows a strong enhancement in the diffracted intensity. The effect is prominent in natural crystals when the electric field is along the c‐axis. This is evidenced by the increase in the intensity of X‐ray rocking curves recorded from several crystals. The X‐ray topographs recorded with in situ electric field show extinction contrast consisting of striations parallel to the c‐axis. This contrast disappears during irradiation in the absence of an electric field. The increase in the diffracted intensity and the contrast on the topographs are explained by a model on negative space‐charge collection.
Point Defect Observations by Molecular Dynamics and Calculated TEM Imaging
Authors: Mattei G. , Mazzone A. M.
Published: July 2007

A simulation method which combines molecular dynamics and calculated TEM imaging is presented. The simulation is applied to irradiated crystalline silicon and silver to clarify the minimum amount of disorder which could be experimentally observed. It is found that in Si isolated cascades formed at energies near the displacement threshold are clearly visible, while in Ag observable disordered regions are generated only by the overlapping of many cascades launched with energy well above che energy displacement threshold.
Elastic Constants and Phonon Dispersion of Amorphous Copper with Embedded‐Atom Force
Authors: Xie Qian , Huang Meichun
Published: July 2007

Elastic constants and phonon dispersion of amorphous copper are studied by assuming that the interatomic potential is transferable from the crystalline state and can be represented by the analytical model of the embedded‐atom method given by Johnson. To test its effectiveness, the force model used to calculate the phonon eigenfrequencies in the copper crystal and the result is in perfect agreement with experimental values measured at 80 K. Based on the embedded‐atom method and in connection with the radial distribution function, the formulae for calculating the elastic constants of the amorphous phase and the modified Takeno‐Goda formula for studying phonon dispersion in amorphous materials are presented. For an easy implementation, the formulae are simplified by using the Bhatia‐Singh approximation, in which only the nearest‐neighbour contribution is considered.
Thermoelectric Power and Thermal Conductivity of Neutron Irradiated Superconductors YBa2Cu4O8
Authors: Pekala M. , Morawski A. , Łada T. , Mąka E.
Published: July 2007

The first thermoelectric investigation of fast neutron irradiated polycrystalline superconductors YBa2Cu4O8 reveals that with a rising fluence the absolute values of thermoelectric power increase gradually, the transition temperature shifts from 77 to 72 K, whereas the thermal conductivity diminishes due to the suppression of electron and phonon mean free paths by the defects created in the CuO2 layers.