3,529 research outputs found

    Why is timing of bird migration advancing when individuals are not?

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    Recent advances in spring arrival dates have been reported in many migratory species but the mechanism driving these advances is unknown. As population declines are most widely reported in species that are not advancing migration, there is an urgent need to identify the mechanisms facilitating and constraining these advances. Individual plasticity in timing of migration in response to changing climatic conditions is commonly proposed to drive these advances but plasticity in individual migratory timings is rarely observed. For a shorebird population that has significantly advanced migration in recent decades, we show that individual arrival dates are highly consistent between years, but that the arrival dates of new recruits to the population are significantly earlier now than in previous years. Several mechanisms could drive advances in recruit arrival, none of which require individual plasticity or rapid evolution of migration timings. In particular, advances in nest-laying dates could result in advanced recruit arrival, if benefits of early hatching facilitate early subsequent spring migration. This mechanism could also explain why arrival dates of short-distance migrants, which generally return to breeding sites earlier and have greater scope for advance laying, are advancing more rapidly than long-distance migrants

    Internal Energy of the Potts model on the Triangular Lattice with Two- and Three-body Interactions

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    We calculate the internal energy of the Potts model on the triangular lattice with two- and three-body interactions at the transition point satisfying certain conditions for coupling constants. The method is a duality transformation. Therefore we have to make assumptions on uniqueness of the transition point and that the transition is of second order. These assumptions have been verified to hold by numerical simulations for q=2, 3 and 4, and our results for the internal energy are expected to be exact in these cases.Comment: 9 pages, 4 figure

    Potts-Percolation-Gauss Model of a Solid

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    We study a statistical mechanics model of a solid. Neighboring atoms are connected by Hookian springs. If the energy is larger than a threshold the "spring" is more likely to fail, while if the energy is lower than the threshold the spring is more likely to be alive. The phase diagram and thermodynamic quantities, such as free energy, numbers of bonds and clusters, and their fluctuations, are determined using renormalization-group and Monte-Carlo techniques.Comment: 10 pages, 12 figure

    Gas-plasma compressional wave coupling by momentum transfer

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    Pressure disturbances in a gas-plasma mixed fluid will result in a hybrid response, with magnetosonic plasma waves coupled to acoustic waves in the neutral gas. In the analytical and numerical treatment presented here, we demonstrate the evolution of the total fluid medium response under a variety of conditions, with the gas-plasma linkage achieved by additional coupling terms in the momentum equations of each species. The significance of this treatment lies in the consideration of density perturbations in such fluids: there is no 'pure' mode response, only a collective one in which elements of the characteristics of each component are present. For example, an initially isotropic gas sound wave can trigger an anisotropic magnetic response in the plasma, with the character of each being blended in the global evolution. Hence sound waves do not remain wholly isotropic, and magnetic responses are less constrained by pure magnetoplasma dynamics

    Integrability of the critical point of the Kagom\'e three-state Potts mode

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    The vicinity of the critical point of the three-state Potts model on a Kagom\'e lattice is studied by mean of Random Matrix Theory. Strong evidence that the critical point is integrable is given.Comment: 1 LaTex file + 3 eps files 7 page

    Impact of a family medicine resident wellness curriculum: a feasibility study

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    BACKGROUND: Up to 60% of practicing physicians report symptoms of burnout, which often peak during residency. Residency is also a relevant time for habits of self-care and resiliency to be emphasized. A growing literature underscores the importance of this; however, evidence about effective burnout prevention curriculum during residency remains limited. OBJECTIVES: The purpose of this project is to evaluate the impact of a new, 1-month wellness curriculum for 12 second-year family medicine residents on burnout, empathy, stress, and self-compassion. METHODS: The pilot program, introduced during a new rotation emphasizing competencies around leadership, focused on teaching skills to cultivate mindfulness and self-compassion in order to enhance empathy and reduce stress. Pre-assessments and 3-month follow-up assessments on measures of burnout, empathy, self-compassion, and perceived stress were collected to evaluate the impact of the curriculum. It was hypothesized that this curriculum would enhance empathy and self-compassion as well as reduce stress and burnout among family medicine residents. RESULTS: Descriptive statistics revealed positive trends on the mean scores of all the measures, particularly the Mindfulness Scale of the Self-Compassion Inventory and the Jefferson Empathy Scale. However, the small sample size and lack of sufficient power to detect meaningful differences limited the use of inferential statistics. CONCLUSIONS: This feasibility study demonstrates how a residency wellness curriculum can be developed, implemented, and evaluated with promising results, including high participant satisfaction

    Monte Carlo Simulations of Conformal Theory Predictions for the 3-state Potts and Ising Models

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    The critical properties of the 2D Ising and 3-state Potts models are investigated using Monte Carlo simulations. Special interest is given to measurement of 3-point correlation functions and associated universal objects, i.e. structure constants. The results agree well with predictions coming from conformal field theory confirming, for these examples, the correctness of the Coulomb gas formalism and the bootstrap method.Comment: 11 pages, 6 Postscript figures, uses Revte

    Monte Carlo Study of an Extended 3-State Potts Model on the Triangular Lattice

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    By introducing a chiral term into the Hamiltonian of the 3-state Potts model on a triangular lattice additional symmetries are achieved between the clockwise and anticlockwise states and the ferromagnetic state. This model is investigated using Monte Carlo methods. We investigate the full phase diagram and find evidence for a line tricritical points separating the ferromagnetic and antiferromagnetic phases.Comment: 6 pages, 10 figure
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