5,115 research outputs found

    Focusing RKKY interaction by graphene P-N junction

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    The carrier-mediated RKKY interaction between local spins plays an important role for the application of magnetically doped graphene in spintronics and quantum computation. Previous studies largely concentrate on the influence of electronic states of uniform systems on the RKKY interaction. Here we reveal a very different way to manipulate the RKKY interaction by showing that the anomalous focusing - a well-known electron optics phenomenon in graphene P-N junctions - can be utilized to refocus the massless Dirac electrons emanating from one local spin to the other local spin. This gives rise to rich spatial interference patterns and symmetry-protected non-oscillatory RKKY interaction with a strongly enhanced magnitude. It may provide a new way to engineer the long-range spin-spin interaction in graphene.Comment: 9 pages, 4 figure

    Pharmacological activation of the amygdala, but not single prolonged footshock-induced acute stress, interferes with cue-induced motivation toward food rewards in rats

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    In the face of threats, animals adapt their behaviors to cope with the situation. Under such circumstances, irrelevant behaviors are usually suppressed. In this study, we examined whether food-seeking motivation would decrease under activation of the amygdala, an important nucleus in the regulation of stress response in the central nervous system, or after a physical acute stress session. In Experiment 1, we pharmacologically activated the basolateral nucleus (BLA) or the central nucleus of the amygdala (CeA) before a cue-induced reinstatement test in rats. Our results showed that activation of the BLA or the CeA abolished cue-induced motivation toward food rewards, while locomotor activity and free food intake were not affected. In Experiments 2 and 3, we further assessed anxiety and despair levels, as well as cue-induced reinstatement, after a single prolonged footshock-induced acute stress in rats. Behaviorally, acute stress did not affect anxiety level, despair level, or cue-induced motivation toward food rewards. Physiologically, there was no difference in cellular activities of the amygdala immediately after acute stress. To conclude, our results suggested that pharmacological activation of the amygdala decreased cue-induced motivation toward food reward. However, physiological acute stress did not immediately interfere with the negative emotions, motivation, or amygdala activities of the animals

    Phonon Effects on Spin-Charge Separation in One Dimension

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    Phonon effects on spin-charge separation in one dimension are investigated through the calculation of one-electron spectral functions in terms of the recently developed cluster perturbation theory together with an optimized phonon approach. It is found that the retardation effect due to the finiteness of phonon frequency suppresses the spin-charge separation and eventually makes it invisible in the spectral function. By comparing our results with experimental data of TTF-TCNQ, it is observed that the electron-phonon interaction must be taken into account when interpreting the ARPES data.Comment: 5 pages, 5 figures, minor differences with the published version in Physical Review Letter

    Noise-Constrained Performance Optimization by Simultaneous Gate and Wire Sizing Based on Lagrangian Relaxation

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    Noise, as well as area, delay, and power, is one of the most important concerns in the design of deep sub-micron ICs. Currently existing algorithms can not handle simultaneous switching conditions of signals for noise minimization. In this paper, we model not only physical coupling capacitance, but also simultaneous switching behavior for noise optimization. Based on Lagrangian relaxation, we present an algorithm that can optimally solve the simultaneous noise, area, delay, and power optimization problem by sizing circuit components. Our algorithm, with linear memory requirement overall and linear runtime per iteration, is very effective and efficient. For example, for a circuit of 6144 wires and 3512 gates, our algorithm solves the simultaneous optimization problem using only 2.1 MB memory and 47 minute runtime to achieve the precision of within 1% error on a SUN UltraSPARC-I workstation

    Population Stereotyped Icons: A Study of Agrarian Communities in India

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    Knowledge transfer is a key factor for increasing agriculture yield especially in developing countries like India. Information Communication Technologies (ICT) is the best platform for knowledge transfer. However, the expertise level of novice users living in India has compromised usage of ICT services. To fill the gap, we suggest for icons to be developed using population stereotype production method. In this study, we first generated population stereotype representations for sixteen different function labels. We then compared the performance and representativeness of these populationstereotyped icons with other ideas. Two separate experiments were conducted. In the first experiment, ninety-two participants from the farming communities were asked to draw images to represent sixteen function labels. In the second experiment, eighty-eight participants were equally distributed into four groups to evaluate the performance and representativeness of all the population-stereotyped representations. This study answered one of the most significant questions regarding the utility of using population-stereotyped ideas for the development of icons in the context of agrarian societies of rural India. The study also offered important practical implications for designing representative icons by using representations developed by different participants during population stereotype production

    INFORMATION PRIVACY CONCERNS AMONG NOVICE AND EXPERT USERS OF SOLOMO

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    SoLoMo (Social-Local-Mobile) services are becoming dominant to the huge population of semiliterate users living in emerging economies due to low costs and ubiquity. However, usage of SoLoMo services is still susceptible by information privacy concerns. Studies typically addressed the ways to mitigate information privacy concerns for the literate users and not the semi-literate users. To fill the gap of semi-literate users and have a better understanding of the information privacy concerns among different communities, this study draws upon theories of privacy calculus, familiarity, intrinsic and extrinsic motivation and protection motivation to identify the precursors of information privacy concerns related to SoLoMo services and users’ expertise. The proposed research model is empirically tested in a laboratory experiment. The findings show that the two channels (covert and overt) of delivering SoLoMo services affect the degree of information privacy concerns between the literate and semi-literate users. Implications for improving usage intentions and mitigating information privacy concerns for SoLoMo services for different types of mobile applications are discussed
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