1,918 research outputs found

    Early supportive medication use and end-of-life care among Medicare beneficiaries with advanced breast cancer

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    A randomized controlled trial of cancer patients has linked early supportive care with improved hospice use and less aggressive end-of-life care. In practice, the early use of supportive interventions and potential impact on end-of-life care are poorly understood. We sought to describe early use of medications to treat common breast cancer symptoms (pain, insomnia, anxiety, and depression) and to assess the relationship between early use of these treatments and end-of-life care

    The puzzle of 90 degree reorientation in the vortex lattice of borocarbide superconductors

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    We explain 90 degree reorientation in the vortex lattice of borocarbide superconductors on the basis of a phenomenological extension of the nonlocal London model that takes full account of the symmetry of the system. We propose microscopic mechanisms that could generate the correction terms and point out the important role of the superconducting gap anisotropy.Comment: 4 pages, 2 eps figure

    Ballistic transport, chiral anomaly and emergence of the neutral electron - hole plasma in graphene

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    The process of coherent creation of particle - hole excitations by an electric field in graphene is quantitatively described using a dynamic "first quantized" approach. We calculate the evolution of current density, number of pairs and energy in ballistic regime using the tight binding model. The series in electric field strength EE up to third order in both DC and AC are calculated. We show how the physics far from the two Dirac points enters various physical quantities in linear response and how it is related to the chiral anomaly. The third harmonic generation and the imaginary part of conductivity are obtained. It is shown that at certain time scale tnlE1/2t_{nl}\propto E^{-1/2} the physical behaviour dramatically changes and the perturbation theory breaks down. Beyond the linear response physics is explored using an exact solution of the first quantized equations. While for small electric fields the I-V curve is linear characterized by the universal minimal resistivity σ=π/2(e2/h)\sigma =\pi /2(e^{2}/h)%, at t>tnlt>t_{nl} the conductivity grows fast. The copious pair creation (with rate E3/2E^{3/2}), analogous to Schwinger's electron - positron pair creation from vacuum in QED, leads to creation of the electron - hole plasma at ballistic times of order tnlt_{nl}. This process is terminated by a relaxational recombination.Comment: 15 pages, 5 figures

    Can Sigma Models Describe Finite Temperature Chiral Transitions?

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    Large-N expansions and computer simulations indicate that the universality class of the finite temperature chiral symmetry restoration transition in the 3D Gross-Neveu model is mean field theory. This is a counterexample to the standard 'sigma model' scenario which predicts the 2D Ising model universality class. We trace the breakdown of the standard scenario (dimensional reduction and universality) to the absence of canonical scalar fields in the model. We point out that our results could be generic for theories with dynamical symmetry breaking, such as Quantum Chromodynamics.Comment: 9 pages, 2 ps figure

    Play Pedagogy, STEM, and Inquiry: Using Mousetrap Cars to Bridge Metacognition

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    Educators are eager to embrace the complexities of 21st century instruction, which presents challenges for integrating science, technology, engineering, and mathematics (STEM) into K-12 instructional practices. Although there are a variety of methodologies for STEM, focusing on play pedagogy and inquiry will facilitate student engagement in metacognitive skills that are necessary components of STEM constructs. Metacognition activates critical thinking skills such as collaborative planning for problem solving, analyzing, self-regulation, and evaluating. Additionally, student motivation is maximized when student led learning results in authentic student products. When educators are provided with support that guides methods for implementation, they will be more successful in the classroom. This completed practice project will present the audience with components for a STEM model that includes context, purposes, methods, evidence, analysis, scholarly discussions, and recommendations. The audience will directly experience the thrill of engaging in collaboration to plan, design, and build mousetrap cars within the context of a STEM lesson

    Nature of 45 degree vortex lattice reorientation in tetragonal superconductors

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    The transformation of the vortex lattice in a tetragonal superconductor which consists of its 45 degree reorientation relative to the crystal axes is studied using the nonlocal London model. It is shown that the reorientation occurs as two successive second order (continuous) phase transitions. The transition magnetic fields are calculated for a range of parameters relevant for borocarbide superconductors in which the reorientation has been observed

    Thermal fluctuations and disorder effects in vortex lattices

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    We calculate using loop expansion the effect of fluctuations on the structure function and magnetization of the vortex lattice and compare it with existing MC results. In addition to renormalization of the height of the Bragg peaks of the structure function, there appears a characteristic saddle shape ''halos'' around the peaks. The effect of disorder on magnetization is also calculated. All the infrared divergencies related to soft shear cancel.Comment: 10 pages, revtex file, one figur
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