bluuebunny/crossref_metadata_2025 huggingface dataset:
Optoelectronic response calculations in the framework of k·p coupled to non-equilibrium Green's functions for one-dimensional systems in the ballistic limit
Authors: Buin Andrei , Verma Amit , Saini Simarjeet
Published: July 2013

We present theory of the carrier-optical interaction in 1D systems based on the nonequilibrium Green's function formalism in the 4 × 4 k·p model. As representative parameters, we chose the GaAs. Results and discussion section is based on the simplified model such as 2 × 2 k·p model (two transverse modes). Even though 2 × 2 k·p model is simple enough, it shows many phenomena that have not been seen before. We focus mainly on the ballistic extraction of photogenerated free carriers at the radiative limit which is described by the self-energy term derived in dipole approximation and solved in self-consistent manner with Keldysh quantum kinetic equations. Any relaxation or non-radiative recombination mechanisms as well as excitonic features are neglected. Effect of non-locality of electron-photon self energy term is considered and discussed. Spontaneous emission is also considered and shown to be small in short devices under medium bias conditions. Electron and hole spatial current oscillations are seen and discussed. It is shown that neglecting off-diagonal correlation in the band index not only produces quantitatively wrong results but it also alters the qualitative picture. All simulations are done in the full-rank approximation, with all spatial and band correlation effects kept intact. This allows us to study not only quantitative effects but also qualitative behaviour.
Tuning the thermal conductivity of silicene with tensile strain and isotopic doping: A molecular dynamics study
Authors: Pei Qing-Xiang , Zhang Yong-Wei , Sha Zhen-Dong , Shenoy Vivek B.
Published: July 2013

Silicene is a monolayer of silicon atoms arranged in honeycomb lattice similar to graphene. We study the thermal transport in silicene by using non-equilibrium molecular dynamics simulations. We focus on the effects of tensile strain and isotopic doping on the thermal conductivity, in order to tune the thermal conductivity of silicene. We find that the thermal conductivity of silicene, which is shown to be only about 20% of that of bulk silicon, increases at small tensile strains but decreases at large strains. We also find that isotopic doping of silicene results in a U-shaped change of the thermal conductivity for the isotope concentration varying from 0% to 100%. We further show that ordered doping (isotope superlattice) leads to a much larger reduction in thermal conductivity than random doping. Our findings are important for the thermal management in silicene-based electronic devices and for thermoelectric applications of silicene.
Strain localization in a nanocrystalline metal: Atomic mechanisms and the effect of testing conditions
Authors: Rupert Timothy J.
Published: July 2013

Molecular dynamics simulations are used to investigate strain localization in a model nanocrystalline metal. The atomic mechanisms of such catastrophic failure are first studied for two grain sizes of interest. Detailed analysis shows that the formation of a strain path across the sample width is crucial and can be achieved entirely through grain boundary deformation or through a combination of grain boundary sliding and grain boundary dislocation emission. Pronounced mechanically induced grain growth is also found within the strain localization region. The effects of testing conditions on strain localization are also highlighted, to understand the conditions that promote shear banding and compare these observations to metallic glass behavior. We observed that, while strain localization occurs at low temperatures and slow strain rates, a shift to more uniform plastic flow is observed when either strain rate or temperature is increased. We also explore how external sample dimensions influence strain localization, but find no size effect for the grain sizes and samples sizes studied here.
Controlling the conductivity of amorphous LaAlO3/SrTiO3 interfaces by in-situ application of an electric field during fabrication
Authors: Trier F. , Amoruso S. , Christensen D. V. , Sambri A. , Chen Y. Z. , Wang X. , Stamate E. , Bruzzese R. , Pryds N.
Published: July 2013

Amorphous-LaAlO3/SrTiO3 interfaces present metallic conductivity similar to those found in their all-crystalline counterparts. Here, the conductivity of amorphous-LaAlO3/SrTiO3 interfaces is modified by an external electric field applied in-situ with a biased truncated cone electrode (−10 V ≤ Vbias ≤ 20 V) during film growth. By modulating the charge balance of the arriving plasma species, interfacial conduction of the amorphous-LaAlO3/SrTiO3 heterostructures shifts from metallic to insulating via a semiconducting-like characteristic transport mode. This remarkable behavior is explained by a modification of the Al-ion flux impinging the SrTiO3 surface, which alters the amount of near-interface oxygen vacancies being formed at the SrTiO3 surface.
Comprehensive characterization of surface acoustic wave resonators using relaxor based ferroelectric single crystals
Authors: Chen Jing , Han Tao , Ji Xiaojun , Zhao Xiangyong , Luo Haosu
Published: July 2013

One-port surface acoustic wave resonators (SAW) were fabricated and characterized using Y-cut X propagating relaxor based ferroelectric single crystals of Pb(Mg1/3Nb2/3)O3-33%PbTiO3 and Pb(In1/3Nb2/3)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT). The experimental results demonstrated ultrahigh electromechanical coupling factor K2 of ∼60% for shear horizontal SAW and a relatively strong spurious resonance due to the Rayleigh-type SAW which can be sufficiently suppressed with Au electrode of large thickness. Characteristics of temperature stability, sensitivity to DC bias voltage, and homogeneity for the two resonators were evaluated and compared. The results showed similar instability of domain structure, and PIN-PMN-PT resonators have better temperature stability, but inferior homogeneity compared to that of PMN-33%PT resonators.
The existence of electron-acoustic shock waves and their interactions in a non-Maxwellian plasma with q-nonextensive distributed electrons
Authors: Han Jiu-Ning , Li Jun-Xiu , He Yong-Lin , Han Zhen-Hai , Dong Guang-Xing , Nan Ya-Gong
Published: July 2013

We present a theoretical investigation for the nonlinear interaction between electron-acoustic shock waves in a nonextensive two-electron plasma. The interaction is governed by a pair of Korteweg-de Vries-Burgers equations. We focus on studying the colliding effects on the propagation of shock waves, more specifically, we have studied the effects of plasma parameters, i.e., the nonextensive parameter q, the “hot” to “cold” electron number density ratio α, and the normalized electron kinematic viscosity η0 on the trajectory changes (phase shifts) of shock waves. It is found that there are trajectory changes (phase shifts) for both colliding shock waves in the present plasma system. We also noted that the nonlinearity has no decisive effect on the trajectory changes, the occurrence of trajectory changes may be due to the combined role played by the dispersion and dissipation of the nonlinear structure. Our theoretical study may be beneficial to understand the propagation and interaction of nonlinear electrostatic waves and may brings a possibility to develop the nonlinear theory of electron-acoustic waves in astrophysical plasma systems.
Optical properties of cubic-phase Cu2GeSe4 single crystal
Authors: Choi S. G. , Donohue A. L. , Marcano G. , Rincón C. , Gedvilas L. M. , Li J. , Delgado G. E.
Published: July 2013

We report optical properties of bulk Cu2GeSe4 single crystal. X-ray powder diffraction measurement shows that this ternary compound forms in the cubic crystal structure and its lattice parameter is 5.5815(3) Å. Spectroscopic ellipsometric measurements are performed from 1.0 to 8.5 eV with the crystal at room temperature. Dielectric function ε = ε1 + iε2, complex refractive index N = n + ik, normal incidence reflectivity R, and absorption coefficients α of Cu2GeSe4 are obtained by modeling the ellipsometric data. The vibrational properties of Cu2GeSe4 are characterized by Raman scattering spectroscopy. The data show four major optical structures whose spectral positions are accurately determined by analyzing the spectra with multiple Gaussian-Lorentzian mixed line profiles.
Mechanism of homeotropic alignment of ferroelectric liquid crystals doped with ferro-fluid and applications
Authors: Joshi Tilak , Singh Shri , Choudhary Amit , Pant R. P. , Biradar A. M.
Published: July 2013

We report homeotropic (HT) alignment of ferroelectric liquid crystal (FLC) doped with various concentrations of ferro-fluid (FF) without using any type of alignment layer. The FF induced HT alignment of FLC was found to be dependent on the doping concentration as revealed by optical micrographs, contact angle, and dielectric spectroscopy studies. Higher water contact angle of FF doped FLC films with respect to pure FLC film suggests higher surface energy of FF doped FLC than the surface energy of substrate. The physico-chemical mechanism together with steric model successfully explains the HT alignment of the studied FLC on the ITO substrate.
Study of the spatial coherence of high order harmonic radiation generated from pre-formed plasma plumes
Authors: Kumar M. , Singhal H. , Chakera J. A. , Naik P. A. , Khan R. A. , Gupta P. D.
Published: July 2013

A study of the spatial coherence of the high order harmonic radiation generated by the interaction of 45 fs Ti:sapphire laser beam with carbon (graphite) plasma plume has been carried out using Young's double slit interferometry. It is observed that the spatial coherence varies with harmonic order, laser focal spot size in plasma plume, and peaks at an optimal spot size. It is also observed that the spatial coherence is higher when the laser pulse is focused before the plasma plume than when focused after the plume, and it decreases with increase in the harmonic order. The optimum laser parameters and the focusing conditions to achieve good spatial coherence with high harmonic conversion have been identified, which is desirable for practical applications of the harmonic radiation.
Multilevel magnetization switching by electric field in c-axis oriented polycrystalline Z-type hexaferrite
Authors: Okumura K. , Haruki K. , Ishikura T. , Hirose S. , Kimura T.
Published: July 2013

Direct and converse magnetoelectric (ME) effects, namely, magnetic-field (B) induced electric polarization (P) and electric-field (E) induced magnetization (M), respectively, were investigated at room temperature for c-axis oriented polycrystalline specimens of a Z-type hexaferrite, Sr3Co2Fe24O41. The B profile of the linear ME coefficient obtained from the converse effect well coincides with that obtained from the direct effect. Furthermore, M-E curves show a substantial hysteretic behavior, which allows reversal and multilevel switching of M by applying pulsed E. The present results demonstrate the feasibility of nonvolatile memory elements by using the ME Z-type hexaferrite at room temperature.
Quantitative measurement of strain field in strained-channel-transistor arrays by scanning moiré fringe imaging
Authors: Kim Suhyun , Kondo Yukihito , Lee Kyungwoo , Byun Gwangsun , Jung Kim Joong , Lee Sunyoung , Lee Kyupil
Published: July 2013

We have applied scanning moiré fringe (SMF) imaging in scanning transmission electron microscopy (STEM) to the quantitative measurement of a strain field introduced in p-type channels of transistors with an embedded Si1−xGex source and drain. The compressive strain field parallel to the channels was revealed by the SMF image. We showed that the quantitative strain profile extracted from the SMF image was coincident with the independent measurement by a high-resolution STEM image. In addition, we demonstrated that the strain measurement by SMF imaging can be performed for an extended field of view that is larger than half a micrometer.
Figure of merit of diamond power devices based on accurately estimated impact ionization processes
Authors: Hiraiwa Atsushi , Kawarada Hiroshi
Published: July 2013

Although a high breakdown voltage or field is considered as a major advantage of diamond, there has been a large difference in breakdown voltages or fields of diamond devices in literature. Most of these apparently contradictory results did not correctly reflect material properties because of specific device designs, such as punch-through structure and insufficient edge termination. Once these data were removed, the remaining few results, including a record-high breakdown field of 20 MV/cm, were theoretically reproduced, exactly calculating ionization integrals based on the ionization coefficients that were obtained after compensating for possible errors involved in reported theoretical values. In this compensation, we newly developed a method for extracting an ionization coefficient from an arbitrary relationship between breakdown voltage and doping density in the Chynoweth's framework. The breakdown field of diamond was estimated to depend on the doping density more than other materials, and accordingly required to be compared at the same doping density. The figure of merit (FOM) of diamond devices, obtained using these breakdown data, was comparable to the FOMs of 4H-SiC and Wurtzite-GaN devices at room temperature, but was projected to be larger than the latter by more than one order of magnitude at higher temperatures about 300 °C. Considering the relatively undeveloped state of diamond technology, there is room for further enhancement of the diamond FOM, improving breakdown voltage and mobility. Through these investigations, junction breakdown was found to be initiated by electrons or holes in a p−-type or n−-type drift layer, respectively. The breakdown voltages in the two types of drift layers differed from each other in a strict sense but were practically the same. Hence, we do not need to care about the conduction type of drift layers, but should rather exactly calculate the ionization integral without approximating ionization coefficients by a power function of electric field as often done in Si devices. In order to facilitate this approach, we developed a method for simplifying the ionization integral, which method, together with the aforementioned method for extracting ionization coefficients, will help to promote the study on breakdown phenomena of all semiconductors.
Interface effect on the magnitude and stability of ferroelectric polarization in ultrathin PbTiO3 films from first-principles study
Authors: Yang Q. , Cao J. X. , Ma Y. , Zhou Y. C. , Lou X. J. , Yang J.
Published: July 2013

The interface effects on the ferroelectric polarization and stability of PbTiO3 (PTO) films with metallic (Pt) or oxide (LaNiO3, SrRuO3) electrodes were studied using density functional theory calculation. It was found that the PTO film with oxide electrodes has stronger electrode/ferroelectric interface adhesion, lower polarization magnitude, and worse polarization stability, than that with Pt electrode. The PbO-terminated PTO films show weaker adhesion with the electrodes, but have higher polarization magnitude and better polarization stability than the TiO2-terminated ones. The strain effects induced by misfit interface were also studied. Results show that the ferroelectric polarization and its stability can be enhanced by applying compressive strain, while depressed by applying tensile strain.
Note: A simple approach to fabricate a microscopic four-point probe for conductivity measurements in ultrahigh vacuum
Authors: Pang Fei , Liang Xuejin , Chen Dongmin
Published: July 2013

We present a simple method to fabricate microscopic four-point probe (M4PP) with spacing of 70–100 μm for conductivity measurements in ultrahigh vacuum. The probe includes four gold wires with 30 μm diameter and a 0.5 mm thickness sapphire slice as cantilever. One of the dual scanning tunneling microscope (DSTM) is replaced by M4PP. As a result, in situ transport measurement could be performed by M4PP and investigation of surface morphology by STM. Finally, we measure conductivity of 14 monolayer Bi(111) epitaxial film on n type Si which is 1.6 × 10−3 Ω−1/□.
Photosynthetic activity of seagrasses and macroalgae in temperate shallow waters can alter seawater pH and total inorganic carbon content at the scale of a coastal embayment
Authors: Buapet Pimchanok , Gullström Martin , Björk Mats
Published: July 2013

Many studies have reported fluctuations in pH and the concentration of dissolved inorganic carbon (DIC) in shallow coastal waters as a result of photosynthetic activity; however, little is known about how these fluctuations vary with degree of exposure among habitats, and at different scales. In the present study, diel variation in seawater pH was apparent in aquaria experiments with Zostera marina and Ruppia maritima. These pH variations were affected by light regime, biomass level and plant species. Subsequently, the natural variability in seawater pH and the concentration of DIC was assessed in six shallow embayments (three sheltered and three exposed) during sunny days. From the outer part towards the interior part of each bay, the following four habitats were identified and studied: the bay-mouth open water, seagrass beds, mixed macrophyte belts and unvegetated bottoms. The two vegetated habitats and unvegetated bottoms were characterised by higher pH and a lower concentration of DIC than in the bay-mouth water. The mixed macrophytes habitat showed slightly higher pH and a lower concentration of DIC than the seagrass and unvegetated habitats. No significant effect of exposure was detected. Our findings clearly showed that the photosynthetic activity of marine macrophytes can alter the coastal pH and the concentration of DIC and that the effects can be observed at the scale of a whole bay.
Validated age, growth and reproductive biology of Carcharhinus melanopterus, a widely distributed and exploited reef shark
Authors: Chin Andrew , Simpfendorfer Colin , Tobin Andrew , Heupel Michelle
Published: July 2013

Inadequate life-history information can compromise management of shark populations. The present study examined the life history of blacktip reef sharks (Carcharhinus melanopterus) from north-eastern Australia with predictions that they would show life-history patterns similar to those of other reef sharks species. Age and growth estimates were derived from vertebrae and five growth models. Males were 543–1390 mm total length (LST) and females were 514–1600 mm LST. Longevity was 10 years (males) and 15 years (females). Chemical marking confirmed annual band pair deposition but indicated probable age underestimation of large individuals. The logistic model was preferred (second-order Akaike information criterion (AICc) weight 0.7536), with growth parameter estimates of length at birth (L0) = 617 mm LST; asymptotic length (L∞) = 1585 mm LST; k (from logistic model) = 0.251 year–1. Males matured at 4.2 years (1050 mm LST) and females at 8.5 years (1335 mm LST), although further verification is needed. Mating and parturition occurred in summer and autumn, females having three or four pups per litter. Data were inconclusive in determining reproductive periodicity. These data contribute to the species management and conservation and suggest that the species may be sensitive to fishing pressure and habitat loss. The study also demonstrated potential complications in using vertebrae to estimate age and growth of chondrichthyan fishes.
Three-dimensional systems for in vitro follicular culture: overview of alginate-based matrices
Authors: Brito Ivina R. , Lima Isadora M. T. , Xu Min , Shea Lonnie D. , Woodruff Teresa K. , Figueiredo José R.
Published: July 2013

The in vitro culture of ovarian follicles has provided critical insight into the biology of the follicle and its enclosed oocyte and the physical interaction and communication between the theca and granulosa cells and the oocyte that is necessary to produce meiotically competent oocytes. Various two-dimensional (2D) and three-dimensional (3D) culture systems have been developed to evaluate the effect of growth factors, hormones, extracellular matrix components and culture conditions on follicle development and oocyte growth and maturation. Among these culture systems, 3D systems make it possible to maintain follicle structure and support communication between the various cell compartments within the follicle. In this review article, we will discuss the three main approaches to ovarian follicle culture: 2D attachment systems, 3D floating systems and 3D encapsulated systems. We will specifically emphasise the development of and advances in alginate-based encapsulated systems for in vitro follicle culture.
HIV pre-exposure prophylaxis and treatment as prevention: a review of awareness and acceptability among men who have sex with men in the Asia-Pacific region and the Americas
Authors: Holt Martin
Published: July 2013

This review assesses acceptability research for HIV pre-exposure prophylaxis (PrEP) and treatment as prevention (TasP) among men who have sex with men (MSM) in the Asia-Pacific region and the Americas, evaluating awareness and attitudes. There has been limited research on the acceptability of PrEP outside the United States and no research to date evaluating the acceptability of TasP since the findings of the HIV Prevention Trials Network 052 trial were released. Existing research suggests that PrEP is reasonably acceptable to MSM, but few men are likely to perceive the need for it. Studies of HIV treatment optimism suggest that MSM are likely to be sceptical of TasP.
Computation of the Euclidean minimum of algebraic number fields
Authors: Lezowski Pierre
Published: July 2013

We present an algorithm to compute the Euclidean minimum of an algebraic number field, which is a generalization of the algorithm restricted to the totally real case described by Cerri in 2007. With a practical implementation, we obtain unknown values of the Euclidean minima of algebraic number fields of degree up to

8
8

in any signature, especially for cyclotomic fields, and many new examples of norm-Euclidean or non-norm-Euclidean algebraic number fields. Then, we show how to apply the algorithm to study extensions of norm-Euclideanity.
Mild cognitive impairment in Parkinson's disease
Authors: Yarnall Alison Jane , Rochester Lynn , Burn David John
Published: July 2013

The concept of mild cognitive impairment (MCI) in the general population has received increased attention over recent years, and is associated with risk of progression to Alzheimer's disease. Within Parkinson's disease (PD), MCI (PD-MCI) is also now recognised to be relatively common, with certain subtypes predicting progression to Parkinson's disease dementia (PDD). Recently, criteria to better characterise PD-MCI and its subtypes have been produced by the Movement Disorder Society. In contrast to the population as a whole, where amnestic MCI is the most common subtype, non-amnestic PD-MCI dominates, with prominent executive and attention dysfunction. Although the pathophysiology of PD-MCI is poorly understood and encompasses both PD and non-PD pathology, it is most likely the result of a complex interaction between neurotransmitter dysfunction, synaptic pathology, protein aggregation and neuronal damage. Determining the factors that influence the progression of these pathologies in PD and the individuals at risk of ultimately developing PDD is critical for targeted intervention and drug discovery studies. Further work is required, however, to determine the significance of PD-MCI and also to validate the diagnostic criteria. This would be best delivered in the form of longitudinal studies in homogenous cohorts of PD participants, to allow prognostication and generalisation among the PD population. At the present time, no drug therapies are available for PD-MCI. Management includes screening for the disorder, excluding treatable causes of cognitive decline and cautious use of dopamine agonists and medications such as anticholinergics.
The CLAMP protein links the MSL complex to the X chromosome during Drosophila dosage compensation
Authors: Soruco Marcela M.L. , Chery Jessica , Bishop Eric P. , Siggers Trevor , Tolstorukov Michael Y. , Leydon Alexander R. , Sugden Arthur U. , Goebel Karen , Feng Jessica , Xia Peng , Vedenko Anastasia , Bulyk Martha L. , Park Peter J. , Larschan Erica
Published: July 2013

The Drosophila male-specific lethal (MSL) dosage compensation complex increases transcript levels on the single male X chromosome to equal the transcript levels in XX females. However, it is not known how the MSL complex is linked to its DNA recognition elements, the critical first step in dosage compensation. Here, we demonstrate that a previously uncharacterized zinc finger protein, CLAMP (chromatin-linked adaptor for MSL proteins), functions as the first link between the MSL complex and the X chromosome. CLAMP directly binds to the MSL complex DNA recognition elements and is required for the recruitment of the MSL complex. The discovery of CLAMP identifies a key factor required for the chromosome-specific targeting of dosage compensation, providing new insights into how subnuclear domains of coordinate gene regulation are formed within metazoan genomes.
Spatially distinct roles of class Ia PI3K isoforms in the development and maintenance of PTEN hamartoma tumor syndrome
Authors: Wang Qi , Von Thanh , Bronson Roderick , Ruan Minzi , Mu Wenxia , Huang Alan , Maira Sauveur-Michel , Zhao Jean J.
Published: July 2013

PTEN hamartoma tumor syndrome (PHTS) comprises a collection of genetic disorders associated with germline mutations in the tumor suppressor gene PTEN. Therapeutic options and preventative measures for PHTS are limited. Using both genetically engineered mouse models and pharmacological PI3K isoform-selective inhibitors, we found that the roles of PI3K isoforms are spatially distinct in the skin: While p110α is responsible for the sustained survival of suprabasal cells of the epidermis in the absence of PTEN, p110β is important for the hyperproliferation of basal cells in PHTS. Furthermore, we identified a differential expression pattern of p110α and p110β in basal and suprabasal keratinocytes as well as differential PI3K regulation by upstream signals in the basal and suprabasal compartments of the epidermis, providing a potential molecular mechanism underlying the specific roles of PI3K isoforms in the epidermis. Finally, we demonstrate that combined inhibition of both PI3K isoforms prevents the development of PHTS and also reverses skin hamartomas that have reached advanced stages in mice. Together, these results not only advance our overall understanding of the diverse roles of PI3K isoforms, but also have the potential for meaningful translation via the clinical utilization of PI3K inhibitors for both prevention and therapy in PHTS patients.
Does the microenvironment influence the cell types of origin for prostate cancer?
Authors: Goldstein Andrew S. , Witte Owen N.
Published: July 2013

Despite several recent studies addressing the cells of origin for prostate cancer, there is still considerable discussion in the field regarding the most relevant target populations for transformation. Tissue regeneration studies have pointed to a basal cell origin for mouse and human prostate cancer. In contrast, genetically engineered mouse models demonstrate that cells within both the basal and luminal layers can initiate murine prostate cancer. Based on differences between these two approaches, we propose that further work should address the requirement for microenvironmental components such as immune or mesenchymal cells on epithelial cell types of origin for prostate cancer.
Active vs. reactive threat responding is associated with differential c-Fos expression in specific regions of amygdala and prefrontal cortex
Authors: Martinez Raquel C.R. , Gupta Nikita , Lázaro-Muñoz Gabriel , Sears Robert M. , Kim Soojeong , Moscarello Justin M. , LeDoux Joseph E. , Cain Christopher K.
Published: July 2013

Active avoidance (AA) is an important paradigm for studying mechanisms of aversive instrumental learning, pathological anxiety, and active coping. Unfortunately, AA neurocircuits are poorly understood, partly because behavior is highly variable and reflects a competition between Pavlovian reactions and instrumental actions. Here we exploited the behavioral differences between good and poor avoiders to elucidate the AA neurocircuit. Rats received Sidman AA training and expression of the activity-dependent immediate-early gene c-fos was measured after a shock-free AA test. Six brain regions with known or putative roles in AA were evaluated: amygdala, periaqueductal gray, nucleus accumbens, dorsal striatum, prefrontal cortex (PFC), and hippocampus. Good avoiders showed little Pavlovian freezing and high AA rates at test, the opposite of poor avoiders. Although c-Fos activation was observed throughout the brain, differential activation was found only in subregions of amygdala and PFC. Interestingly, c-Fos correlated with avoidance and freezing in only five of 20 distinct areas evaluated: lateral amygdala, central amygdala, medial amygdala, basal amygdala, and infralimbic PFC. Thus, activity in specific amygdala–PFC circuits likely mediates the competition between instrumental actions and Pavlovian reactions after AA training. Individual differences in AA behavior, long considered a nuisance by researchers, may be the key to elucidating the AA neurocircuit and understanding pathological response profiles.
Two polymorphs ofN-(2-methoxyphenyl)-4-oxo-4H-chromone-3-carboxamide
Authors: Gomes Ligia R. , Low John Nicolson , Borges Fernanda , Cagide Fernando
Published: July 2013

The title compound, C17H13NO4, crystallizes in two polymorphic forms, each with two molecules in the asymmetric unit and in the monoclinic space groupP21/c. All of the molecules have intramolecular hydrogen bonds involving the amide group. The amide N atoms act as donors to the carbonyl group of the pyrone and also to the methoxy group of the benzene ring. The carbonyl O atom of the amide group acts as an acceptor of the β and β′ C atoms belonging to the aromatic rings. These intramolecular hydrogen bonds have a profound effect on the molecular conformation. In one polymorph, the molecules in the asymmetric unit are linked to form dimers by weak C—H...O interactions. In the other, the molecules in the asymmetric unit are linked by a single weak C—H...O hydrogen bond. Two of these units are linked to form centrosymmetric tetramers by a second weak C—H...O interaction. Further interactions of this type link the molecules into chains, so forming a three-dimensional network. These interactions in both polymorphs are supplemented by π–π interactions between the chromone rings and between the chromone and methoxyphenyl rings.
A mixed chloride/trifluoromethanesulfonate ligand species in a ruthenium(II) complex
Authors: Santiso-Quinones Gustavo , Rodriguez-Lugo Rafael E.
Published: July 2013

The compound [2-(aminomethyl)pyridine-κ2N,N′][chlorido/trifluoromethanesulfonato(0.91/0.09)][(10,11-η)-5H-dibenzo[a,d]cyclohepten-5-amine-κN](triphenylphosphane-κP)ruthenium(II) trifluoromethanesulfonate dichloromethane 0.91-solvate, [Ru(CF3SO3)0.09Cl0.91(C6H8N2)(C15H13N)(C18H15P)]CF3SO3·0.91CH2Cl2, belongs to a series of RuIIcomplexes that had been tested for transfer hydrogenation, hydrogenation of polar bonds and catalytic transfer hydrogenation. The crystal structure determination of this complex revealed disorder in the form of two different anionic ligands sharing the same coordination site, which other spectroscopic methods failed to characterize. The reduced catalytic activity of the title compound was not fully understood until the crystallographic data provided evidence for the mixed ligand species. The crystal structure clearly shows that the majority of the synthesized material has a chloride ligand present. Only a small portion of the material is the expected complex [RuII(OTf)(ampy)(η2-tropNH2)(PPh3)]OTf, where OTf is triflate or trifluoromethanesulfonate, ampy is 2-(aminomethyl)pyridine and tropNH2is 5H-dibenzo[a,d]cyclohepten-5-amine.
Implications of online social activities for e-tailers
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business performance
Authors: Qu Zhe , Wang Youwei , Wang Shan , Zhang Yanhui
Published: July 2013

Purpose

– Despite the growing popularity of internet based social media on e-commerce platforms, systematic examination of the emerging phenomenon is scarce. This paper aims to study whether online retailers
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social activity on e-commerce platforms improves their business performance, and if it does, what are the underlying mechanisms.

Design/methodology/approach

– The paper proposes a typology of online retailers
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social activities on e-commerce platforms. Then drawing on social capital theory and social network theory, the authors develop hypotheses that relate online retailers
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social activities to their business performance. The hypotheses are tested using a large dataset collected from an e-commerce platform in China.

Findings

– The paper shows that: online retailers
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social activities for friend-making improve their business performance, regardless of the directional attribute of the activities; social activities for advice-seeking decrease online retailers
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business performance; and social activities for advice-giving increase online retailers
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business performance.

Research limitations/implications

– The data in the empirical study are from an e-commerce platform in China, hence the research results may lack generalisability. Therefore, researchers are encouraged to test the proposed hypotheses further.

Practical implications

– The paper includes implications for e-commerce market makers and online retailers operating on e-commerce platforms. The authors show that online retailers
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social activities on e-commerce platforms can be an important source of business value. However certain types of social activities may hurt online retailers
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business performance, implying the necessity of a thoughtful social activity strategy in online marketplaces.

Originality/value

– This paper represents an early effort to study whether online retailers
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social activities on e-commerce platforms improve their business performance and the underlying mechanisms of the effect.
Hedonic or utilitarian premiums: does it matter?
Authors: Palazon Mariola , Delgado-Ballester Elena
Published: July 2013

Purpose

– This study aims to analyse what type of premium, hedonic or utilitarian, is preferred in a promotional context. Additionally, it seeks to examine the role of affective and cognitive reactions in decision processes where utilitarian and hedonic premiums are involved.

Design/methodology/approach

– Three experiments were conducted. A single factor within-subjects design was employed, with the nature of the premium (hedonic/utilitarian) as the treatment factor. Respondents were asked to make their choice between two promotional offers. Affective and cognitive reactions were measured. Regression analyses were conducted to test the hypothesized effects.

Findings

– The results show that hedonic premiums are preferable to utilitarian ones in a promotional context, other characteristics of the premium (e.g. premium attractiveness) being equal. The findings also identify that a preference for the hedonic/utilitarian premium is more likely to emerge when affective/cognitive reactions are incited, and indicate that the nature of the preferred premium determines the mediating effect of cognitive reactions.

Research limitations/implications

– The paper only focuses on the hedonic/utilitarian nature of the premium. However, premiums come in very different forms and several characteristics – such as a premium with a relatively low price, the reception delay of the premium, and the perceived fit between the product and the premium – may reverse the relative preference for hedonic premiums.

Practical implications

– The hedonic vs utilitarian nature of the premium should be considered when planning premium promotion. It appears that the use of more hedonic premiums increases the effectiveness of promotional actions alongside other variables such as premium attractiveness, the promotional benefit level or the product-premium fit. Furthermore, the type of premium offered influences the role of affective and cognitive reactions aroused during shopping. Thus, the nature of the premium may influence the reactions of consumers when participating in promotional actions.

Originality/value

– The research extends the factors that may explain the effectiveness of premium promotions, since few studies to date have focused on the hedonic or utilitarian nature of premiums.
Speak my language if you want my money
Authors: Van Vaerenbergh Yves , Holmqvist Jonas
Published: July 2013

Purpose

– Despite the importance of the interaction between consumers and service personnel for how consumers perceive quality, service research assumes that both customers and service provider are perfectly able to interact with each other. This might not be the case on bilingual markets. This paper aims to examine customers
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behavioral reactions to being served in their first versus second language. Specifically, the paper tests whether bilinguals who are served in their second language are less likely to tip the service provider. Moreover, it seeks to examine the mediating role of speech accommodation, and the moderating roles of bilinguals
'
perceived second language proficiency and political considerations.

Design/methodology/approach

– Study 1 tests the main hypothesis using a scenario-based experiment with adult consumers in two bilingual countries (Belgium, Finland). Study 2 further elaborates on these findings using a retrospective survey of actual customer experiences in Belgium.

Findings

– Driven by perceptions of speech accommodation, the results consistently show that consumers are more likely to tip if served in their native language compared to when served in their second language. Moreover, this relationship is not dependent on consumers
'
perceived second language proficiency, but rather upon their political considerations.

Originality/value

– This is the first study of bilingual customers
'
behavioral reactions to being served in their second language, among bilingual customers from different countries. Given that more than half the countries in the world are multilingual, service providers need to take customers
'
native language into account when serving bilingual customers.
Knowledge sharing behaviors of industrial salespeople
Authors: Auh Seigyoung , Menguc Bulent
Published: July 2013

Purpose

– This paper extends the sales literature by moving beyond salespeople
'
s role as knowledge gatherers to their role as knowledge sharers with personnel outside the sales unit. The aim is to develop and test a conceptual model to establish how pay-for-performance (economic factor) affects knowledge sharing behaviour under the contingency roles of coworker relationship quality (social psychological factor) and knowledge sharing norms (sociological factor).

Design/methodology/approach

– Using the Dun
&
Bradstreet database, the authors collected responses from 374 salespeople in 51 Canadian industrial firms through an on-line survey. The authors used hierarchical linear modeling (HLM) as multiple salespeople were nested within the organization and the data were comprised of individual- and organizational-level constructs.

Findings

– When there is misalignment between rewards and knowledge sharing behavior, motivational loss hampers knowledge sharing. However, when employees are provided with an environment that fosters high coworker relationship quality and consensual knowledge sharing norms, the motivational loss resulting from the incongruence between pay-for-performance and knowledge sharing behavior is mitigated.

Research limitations/implications

– Implications regarding how salespeople
'
s knowledge sharing contributes to relationship marketing along with practical ramifications for how sales managers can encourage knowledge sharing are discussed.

Originality/value

– This study contributes to the sales literature (e.g. control, key account management, expanding role of sales) by testing a model that integrates different theoretical perspectives to examine what types of control mechanisms and which combinations of these controls affect salespeople
'
s engagement in knowledge sharing behaviors.
Measuring brand association strength: a consumer based brand equity approach
Authors: French Alan , Smith Gareth
Published: July 2013

Purpose

– To date, the brand equity literature has been limited by a gap in the measurement of a key driver of consumer based brand equity (CBBE). The authors
'
aim is to address this gap by developing a new, consumer-based measure of brand association strength, a critical element of CBBE.

Design/methodology/approach

– This paper, based on cognitive psychology, takes a recently developed brand mapping approach and uses its features, along with network analysis measures designed specifically by the authors for this particular analysis, to produce a novel measure of brand association strength.

Findings

– Traditional network analysis measures (e.g. number of associations, density) neglect to take into account the underlying structure of consumers
'
brand associations as reflected in concept maps. The authors use primary research on a well-known brand (McDonald
'
s) to show that both number of associations and a modified density measure taking account of the special structure of concept maps can be used to generate an intuitive and readily understood measure of brand association strength.

Originality/value

– The paper develops a new measure to analyse brand association strength for any given brand. As such it contributes to the methodological and practical development of the CBBE construct.
Optimization of the permanent magnet brushless DC motor employing finite element method
Authors: Knypiński Łukasz , Nowak Lech
Published: July 2013

Purpose

The purpose of this paper is to elaborate the algorithm and computer code for the structure optimization of the outer rotor permanent magnet brushless DC motor and to execute optimization of selected motor structure using the non‐deterministic procedure.

Design/methodology/approach

The mathematical model of the device includes the electromagnetic field equations with the nonlinearity of the magnetic core taken into account. The numerical implementation is based on the finite element method and stepping procedure. The genetic algorithm has been applied for the optimization. The computer code has been elaborated.

Findings

The elaborated computer software has been applied for the optimization and design of BLDC motors. The elaborated algorithm has been tested and a good convergence has been attained.

Originality/value

The presented approach and computer software can be successfully applied to the design and optimization of different structure of BLDC motors.
Calculation of the flux distribution of three phase five limb power transformers considering nonlinear material properties
Authors: Riemer Björn , Lange Enno , Hameyer Kay
Published: July 2013

Purpose

Depending on the load the flux‐density distribution inside power transformers core shows significant local variations due to stray fluxes which enter the transformer core. As saturation of the core has to be avoided the flux‐density distribution has to be determined early in the design stage of the transformer. This paper seeks to address these issues.

Design/methodology/approach

To determine the load dependent flux‐density distribution the operating point of the transformer is calculated considering linear and non‐linear material properties. The operating point is determined using a linearised lumped parameter model of the transformer under various load conditions. Considering non‐linear material properties the inductance matrix depends on the operating point and will be extracted by means of the FEM whenever the magnetic energy within the transformer changes notably.

Findings

This paper presents a numerical stable approach to calculate the operating point of a transformer by using the magnetic flux linkage as state variable for the coupled field problem.

Research limitations/implications

The proposed approach uses a fixed time‐step to update the lumped parameters by means of the FEM. This results in long simulation times. In further research it is planned to implement an adaptive time‐step method based on the change of the magnetic energy.

Originality/value

A numerical stable approach to calculate the operating point of a transformer by using the magnetic flux linkage as state variable for the coupled field problem is proposed. The methodology is applied to a 2D model of a three‐phase transformer. However, it also can be applied to 3D FE models. Based on the calculated operating point, the flux‐density distribution can be determined and several post‐processing methods can be executed (e.g. determination of core losses, …).
3D analysis of influence of stator winding asymmetry on axial flux
Authors: Pietrowski Wojciech
Published: July 2013

Purpose

The diagnostics of electrical machines is a very important task. The paper seeks to present a study and analysis of stator winding asymmetry in induction motors. The purpose of this paper is presentation of coupling two numerical techniques, a finite element analysis and an artificial neural network, in diagnostics of electrical machines.

Design/methodology/approach

A finite element method (FEM) analysis and time‐stepping are applied for the study of IM with stator winding asymmetry. One of the asymmetry symptoms is an axial flux. In order to determine the level of winding asymmetry a generalized regression neural network has been considered. The result of FFT analysis of axial flux and electromagnetic torque was the input vector to artificial neural network. The output vector is the level of asymmetry. The algorithms are tested using a set data obtained from numerical simulation. The emphasis of this structure is on accurate approximation of the value of the stator winding asymmetry.

Findings

The axial flux, as the symptom of stator winding asymmetry, can contribute to better detection of the asymmetry in stator winding.

Originality/value

It is argued that the proposed method based on axial flux and electromagnetic torque is capable of performing detection of the asymmetry in stator winding. The generalized regression neural network can be used in health monitoring system as an inference module.
Power electronics active shunt filter with controlled dynamics
Authors: Gwóźdź Michał
Published: July 2013

Purpose

The aim of the research was to find a structure of the power electronics controlled current source with extended pass band, which would better match a source output current within an input (reference) signal. Also, pulse modulation components in output current of current source should be minimized.

Design/methodology/approach

The power electronics controlled current source utilizes both, the concept of the inductor with variable (controlled) inductance located at the output of an inverter and the concept of the multi‐channel (interleaved) inverter. The small signal (linear) and simulation models of an active filter have been investigated.

Findings

The work presents the concept of 1‐phase active shunt filter with utilization of the power electronics current source about extended pass‐band.

Research limitations/implications

The research should be continued to achieve stability of the electrical system with variable parameters of the power network and receiver.

Practical implications

The research will be continued towards realization of a laboratory model of a 3‐phase active shunt filter with the DSP based control module.

Social implications

Social implications are difficult to determine.

Originality/value

The paper presents a new concept of the precision power electronics controlled current source with the extended pass‐band. The controlled current source is the fundamental block of a power electronics active shunt filter.