6,025 research outputs found

    Phase Transitions in Non-extensive Spin Systems

    Full text link
    The spherical spin model with infinite-range ferromagnetic interactions is investigated analytically in the framework of non-extensive thermostatics generalizing the Boltzmann-Gibbs statistical mechanics. We show that for repulsive correlations, a new weak-ferromagnetic phase develops. There is a tricritical point separating para, weak-ferro and ferro regimes. The transition from paramagnetic to weak-ferromagnetic phase is an unusual first order phase transition in which a discontinuity of the averaged order parameter appears, even for finite number of spins. This result puts in a new way the question of the stability of critical phenomena with respect to the long-ranged correlations.Comment: 4 pages, 3 figures, in the final form as in the journa

    A recipe for an unpredictable random number generator

    Get PDF
    In this work we present a model for computation of random processes in digital computers which solves the problem of periodic sequences and hidden errors produced by correlations. We show that systems with non-invertible non-linearities can produce unpredictable sequences of independent random numbers. We illustrate our result with some numerical calculations related with random walks simulations.Comment: 8 pages, 5 figures, Proceedings Mochima spring school in theoretial physic

    The workplace integration of veterans: Applying diversity and fit perspectives

    Get PDF
    Military veterans are a valuable part of the human capital resource pool. Nonetheless, veterans often struggle with their transition into civilian life and workplaces. This problem often limits the extent to which work organizations utilize their talents. Here, we briefly review relevant work from outside the management field and nascent work within the field to build a conceptual model for understanding the integration of veterans into the workplace. We do this by applying diversity and person-environment fit perspectives. A diversity standpoint helps us to understand veterans as a social group and their inclusion in the workplace, while the person-environment fit perspective helps us describe veterans’ compatibility with their work environments in terms of organizational demands and veterans’ needs. We intend for this conceptual model to guide future empirical research on veterans as human capital and their transition into civilian organizations as part of their societal reintegration, career development, and personal well-being

    An Integrated Lean Supply Chain Framework for U.S. Hospitals

    Get PDF
    We apply a lean supply chain framework to the healthcare industry in the U.S., drawing support from lean systems philosophy. We conceptualize a view of the U.S. healthcare ecosystem that places a hospital and its admitted patients at the center and describes how all entities inside and outside the hospital work can implement lean principles to improve patients\u27 quality care. This application depicts how a holistic consideration of hospital resources available in both the internal and external supply chain would increase the optimal use of such resources and ultimately serve patients. We offer propositions suggesting that an integrated supply chain perspective would be helpful for delivering high quality of care to patients admitted to the hospital. This perspective suggests that hospitals need to streamline the three types of flows– physical product, information and financial–with elements in the internal supply chain and maintain collaborative relations with entities in their external supply chain. We discuss theoretical and practical implications of our research

    Neural Connectivity with Hidden Gaussian Graphical State-Model

    Full text link
    The noninvasive procedures for neural connectivity are under questioning. Theoretical models sustain that the electromagnetic field registered at external sensors is elicited by currents at neural space. Nevertheless, what we observe at the sensor space is a superposition of projected fields, from the whole gray-matter. This is the reason for a major pitfall of noninvasive Electrophysiology methods: distorted reconstruction of neural activity and its connectivity or leakage. It has been proven that current methods produce incorrect connectomes. Somewhat related to the incorrect connectivity modelling, they disregard either Systems Theory and Bayesian Information Theory. We introduce a new formalism that attains for it, Hidden Gaussian Graphical State-Model (HIGGS). A neural Gaussian Graphical Model (GGM) hidden by the observation equation of Magneto-encephalographic (MEEG) signals. HIGGS is equivalent to a frequency domain Linear State Space Model (LSSM) but with sparse connectivity prior. The mathematical contribution here is the theory for high-dimensional and frequency-domain HIGGS solvers. We demonstrate that HIGGS can attenuate the leakage effect in the most critical case: the distortion EEG signal due to head volume conduction heterogeneities. Its application in EEG is illustrated with retrieved connectivity patterns from human Steady State Visual Evoked Potentials (SSVEP). We provide for the first time confirmatory evidence for noninvasive procedures of neural connectivity: concurrent EEG and Electrocorticography (ECoG) recordings on monkey. Open source packages are freely available online, to reproduce the results presented in this paper and to analyze external MEEG databases

    Internal transitions of negatively charged magnetoexcitons in quantum dots

    Full text link
    We report calculations of oscillator strengths for the far infrared absorption of light by the excitonic complexes Xn- (the excess charge, n, ranging from one to four) confined in quantum dots. The magnetic field is varied in an interval which corresponds to ``filling factors'' between 2 and 3/5. Electron-hole interaction effects are seen in the deviations of the peak positions from the Kohn lines, and in the spreading of the oscillator strengths over a few final states. Transition densities are used as an additional tool to characterize the absorption peaks.Comment: Presented as a poster in the Third Stig Lundqvist Conference on Advancing Frontiers of Condensed Matter Physics: Fundamental Interactions and Excitations in Confined Systems, Trieste, August 11 - 1

    If You Can’t Take the Heat: Cultural Beliefs about Questionable Conduct, Stigma, Punishment, and Withdrawal among Mexican Police Officers

    Get PDF
    We introduce the concept of cultural beliefs about questionable conduct, and examine how these beliefs interact with stigma consciousness to influence punishment and two withdrawal behaviors: turnover and absenteeism. We used a sample of Mexican police officers in a border city and implemented a mixed method design, paying attention to the national, occupational, and organizational context of this setting. We conducted a qualitative phase to explore the prevalence and meaning of occupational stigma and four cultural beliefs about questionable conduct: greed, toughness, wariness, and savvy. The results of this phase helped us develop a context-relevant measure of cultural beliefs about questionable conduct using Mexican proverbs. The results of the quantitative phase indicated that, contingent upon stigma consciousness, beliefs about questionable conduct affected received punishment, turnover, and absenteeism. We discuss the theoretical and behavioral implications of our findings for socialization, identity management, occupational stigma, corruption, and ethical behavior
    corecore