2,237 research outputs found

    Re-injury Anxiety & Return-to-Sport Outcomes in College Students

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    When athletes are injured, they are faced with the initial injury stage, physical therapy, rehabilitation, and then the return-to-sport. When athletes have a negative outlook, they are less likely to recover from the injury at the proposed date of return-to-sport, take a longer span of time to recover, and have higher levels of stress and anxiety. Wadey, Podlog, Hall, Hamson-Utley, Hicks-Little, & Hammer, (2014) examined the dimensions of reinjury anxiety and found athletes with greater reinjury anxiety were in denial of the severity of their injury by wishing things would get better and had a greater focus on their distress. Significant indirect effects for coping were found for wishful thinking, venting of emotions, denial, and behavioral disengagement (Wadey et al., 2014). The purpose of the present study is to examine reinjury anxiety and return-to-sport outcomes within college students. Participants (n=100) solicited from Dominican University and different social networks will be sent an email containing the Reinjury Anxiety Inventory (Walker, Thatcher & Lavallee, 2010), the Return to Sport After Serious Injury Questionnaire (Podlog & Eklund, 2005) and demographic items including type of injury and sport. These questionnaires measure the level of reinjury anxiety and if the perspective of the injury is positive or negative. It is hypothesized: 1) Those with greater reinjury anxiety will be kept out of their sport longer than those who experience less reinjury anxiety and negative thoughts, 2) It will take the participants with greater anxiety longer to recover, and 3) With a negative attitude, personal perspective of actual length of injury will be skewed. Participants with a negative perspective will have higher anxiety with their injury versus participants with a more positive perspective. Data collection will begin approximately in February 2015

    Instability of human societies as a result of conformity

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    We introduce a new model that mimics the strong and sudden effects induced by conformity in tightly interacting human societies. Such effects range from mere crowd phenomena to dramatic political turmoil. The model is a modified version of the Ising Hamiltonian. We have studied the properties of this Hamiltonian using both a Metropolis simulation and analytical derivations. Our study shows that increasing the value of the conformity parameter, results in a first order phase transition. As a result a majority of people begin honestly to support the idea that may contradict the moral principles of a normal human beings though each individual would support the moral principle without tight interaction with the society. Thus, above some critical level of conformity our society occurs to be instable with respect to ideas that might be doubtful. Our model includes, in a simplified way, human diversity with respect to loyalty to the moral principles.Comment: 5 pages, 5 figures, accepted in Int. journ of modern physics section

    Measuring thermodynamic length

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    Thermodynamic length is a metric distance between equilibrium thermodynamic states. Among other interesting properties, this metric asymptotically bounds the dissipation induced by a finite time transformation of a thermodynamic system. It is also connected to the Jensen-Shannon divergence, Fisher information and Rao's entropy differential metric. Therefore, thermodynamic length is of central interest in understanding matter out-of-equilibrium. In this paper, we will consider how to define thermodynamic length for a small system described by equilibrium statistical mechanics and how to measure thermodynamic length within a computer simulation. Surprisingly, Bennett's classic acceptance ratio method for measuring free energy differences also measures thermodynamic length.Comment: 4 pages; Typos correcte

    Generalized Jarzynski Equality under Nonequilibrium Feedback Control

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    The Jarzynski equality is generalized to situations in which nonequilibrium systems are subject to a feedback control. The new terms that arise as a consequence of the feedback describe the mutual information content obtained by measurement and the efficacy of the feedback control. Our results lead to a generalized fluctuation-dissipation theorem that reflects the readout information, and can be experimentally tested using small thermodynamic systems. We illustrate our general results by an introducing "information ratchet," which can transport a Brownian particle in one direction and extract a positive work from the particle

    Quantum Brayton cycle with coupled systems as working substance

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    We explore the quantum version of Brayton cycle with a composite system as the working substance. The actual Brayton cycle consists of two adiabatic and two isobaric processes. Two pressures can be defined in our isobaric process, one corresponds to the external magnetic field (characterized by FxF_x) exerted on the system, while the other corresponds to the coupling constant between the subsystems (characterized by FyF_y). As a consequence, we can define two types of quantum Brayton cycle for the composite system. We find that the subsystem experiences a quantum Brayton cycle in one quantum Brayton cycle (characterized by FxF_x), whereas the subsystem's cycle is of quantum Otto in another Brayton cycle (characterized by FyF_y). The efficiency for the composite system equals to that for the subsystem in both cases, but the work done by the total system are usually larger than the sum of work done by the two subsystems. The other interesting finding is that for the cycle characterized by FyF_y, the subsystem can be a refrigerator while the total system is a heat engine. The result in the paper can be generalized to a quantum Brayton cycle with a general coupled system as the working substance.Comment: 7 pages, 3 figures, accepted by Phys. Rev.

    THE INFLUENCE OF PSYCHOTHERAPY INTERVENTION IN MASS VIOLENCE SETTINGS: A CASE OF KENYA’S POST ELECTION VIOLENCE

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    Mass violence, just like Kenya’s Post election violence, inevitably always results in trauma, which, if not confronted with psychotropic medicine or therapy, may never heal. Consequently, the preparedness of humanitarian agencies to provide psychotherapy is an interventional strategy is important.  This study sought to determine the extent to which, and factors that influence the use of psychotherapy in confronting trauma. It administered a questionnaire and an interview schedule to respondents drawn from IDPs and professionals from humanitarian agencies.  The study found that psychotherapy covered about 84% of PEV victims and improved their social and personality adjustments. In addition, time response and intervener skills were found to be significant in improving its effectiveness.   Key words: psychotherapy, trauma, violence, election, humanitarian agencies

    Numerical renormalization group calculation of impurity internal energy and specific heat of quantum impurity models

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    We introduce a method to obtain the specific heat of quantum impurity models via a direct calculation of the impurity internal energy requiring only the evaluation of local quantities within a single numerical renormalization group (NRG) calculation for the total system. For the Anderson impurity model, we show that the impurity internal energy can be expressed as a sum of purely local static correlation functions and a term that involves also the impurity Green function. The temperature dependence of the latter can be neglected in many cases, thereby allowing the impurity specific heat, CimpC_{\rm imp}, to be calculated accurately from local static correlation functions; specifically via Cimp=EionicT+1/2EhybTC_{\rm imp}=\frac{\partial E_{\rm ionic}}{\partial T} + 1/2\frac{\partial E_{\rm hyb}}{\partial T}, where EionicE_{\rm ionic} and EhybE_{\rm hyb} are the energies of the (embedded) impurity and the hybridization energy, respectively. The term involving the Green function can also be evaluated in cases where its temperature dependence is non-negligible, adding an extra term to CimpC_{\rm imp}. For the non-degenerate Anderson impurity model, we show by comparison with exact Bethe ansatz calculations that the results recover accurately both the Kondo induced peak in the specific heat at low temperatures as well as the high temperature peak due to the resonant level. The approach applies to multiorbital and multichannel Anderson impurity models with arbitrary local Coulomb interactions. An application to the Ohmic two state system and the anisotropic Kondo model is also given, with comparisons to Bethe ansatz calculations. The new approach could also be of interest within other impurity solvers, e.g., within quantum Monte Carlo techniques.Comment: 16 pages, 15 figures, published versio

    AFM pulling and the folding of donor-acceptor oligorotaxanes: phenomenology and interpretation

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    The thermodynamic driving force in the self-assembly of the secondary structure of a class of donor-acceptor oligorotaxanes is elucidated by means of molecular dynamics simulations of equilibrium isometric single-molecule force spectroscopy AFM experiments. The oligorotaxanes consist of cyclobis(paraquat-\emph{p}-phenylene) rings threaded onto an oligomer of 1,5-dioxynaphthalenes linked by polyethers. The simulations are performed in a high dielectric medium using MM3 as the force field. The resulting force vs. extension isotherms show a mechanically unstable region in which the molecule unfolds and, for selected extensions, blinks in the force measurements between a high-force and a low-force regime. From the force vs. extension data the molecular potential of mean force is reconstructed using the weighted histogram analysis method and decomposed into energetic and entropic contributions. The simulations indicate that the folding of the oligorotaxanes is energetically favored but entropically penalized, with the energetic contributions overcoming the entropy penalty and effectively driving the self-assembly. In addition, an analogy between the single-molecule folding/unfolding events driven by the AFM tip and the thermodynamic theory of first-order phase transitions is discussed and general conditions, on the molecule and the cantilever, for the emergence of mechanical instabilities and blinks in the force measurements in equilibrium isometric pulling experiments are presented. In particular, it is shown that the mechanical stability properties observed during the extension are intimately related to the fluctuations in the force measurements.Comment: 42 pages, 17 figures, accepted to the Journal of Chemical Physic

    Proof of Rounding by Quenched Disorder of First Order Transitions in Low-Dimensional Quantum Systems

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    We prove that for quantum lattice systems in d<=2 dimensions the addition of quenched disorder rounds any first order phase transition in the corresponding conjugate order parameter, both at positive temperatures and at T=0. For systems with continuous symmetry the statement extends up to d<=4 dimensions. This establishes for quantum systems the existence of the Imry-Ma phenomenon which for classical systems was proven by Aizenman and Wehr. The extension of the proof to quantum systems is achieved by carrying out the analysis at the level of thermodynamic quantities rather than equilibrium states.Comment: This article presents the detailed derivation of results which were announced in Phys. Rev. Lett. 103 (2009) 197201 (arXiv:0907.2419). v3 incorporates many corrections and improvements resulting from referee comment

    An Exact Solution to O(26) Sigma Model coupled to 2-D Gravity

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    By a mapping to the bosonic string theory, we present an exact solution to the O(26) sigma model coupled to 2-D quantum gravity. In particular, we obtain the exact gravitational dressing to the various matter operators classified by the irreducible representations of O(26). We also derive the exact form of the gravitationally modified beta function for the original coupling constant e2e^2. The relation between our exact solution and the asymptotic solution given in ref[3] is discussed in various aspects.Comment: 10 pages, pupt-144
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