1,531 research outputs found

    Fluctuations and Intrinsic Pinning in Layered Superconductors

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    A flux liquid can condense into a smectic crystal in a pure layered superconductors with the magnetic field oriented nearly parallel to the layers. If the smectic order is commensurate with the layering, this crystal is {\sl stable} to point disorder. By tilting and adjusting the magnitude of the applied field, both incommensurate and tilted smectic and crystalline phases are found. We discuss transport near the second order smectic freezing transition, and show that permeation modes lead to a small non--zero resistivity and large but finite tilt modulus in the smectic crystal.Comment: 4 pages + 1 style file + 1 figure (as uufile) appended, REVTEX 3.

    Conformally invariant bending energy for hypersurfaces

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    The most general conformally invariant bending energy of a closed four-dimensional surface, polynomial in the extrinsic curvature and its derivatives, is constructed. This invariance manifests itself as a set of constraints on the corresponding stress tensor. If the topology is fixed, there are three independent polynomial invariants: two of these are the straighforward quartic analogues of the quadratic Willmore energy for a two-dimensional surface; one is intrinsic (the Weyl invariant), the other extrinsic; the third invariant involves a sum of a quadratic in gradients of the extrinsic curvature -- which is not itself invariant -- and a quartic in the curvature. The four-dimensional energy quadratic in extrinsic curvature plays a central role in this construction.Comment: 16 page

    Evidence for a bind-then-bend mechanism for architectural DNA binding protein yNhp6A

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    The yeast Nhp6A protein (yNhp6A) is a member of the eukaryotic HMGB family of chromatin factors that enhance apparent DNA flexibility. yNhp6A binds DNA nonspecifically with nM affinity, sharply bending DNA by \u3e60◦. It is not known whether the protein binds to unbent DNA and then deforms it, or if bent DNA conformations are ‘captured’ by protein binding. The former mechanism would be supported by discovery of conditions where unbent DNA is bound by yNhp6A. Here, we employed an array of conformational probes (FRET, fluorescence anisotropy, and circular dichroism) to reveal solution conditions in which an 18- base-pair DNA oligomer indeed remains bound to yNhp6A while unbent. In 100 mM NaCl, yNhp6Abound DNA unbends as the temperature is raised, with no significant dissociation of the complex detected up to ∼45◦C. In 200 mM NaCl, DNA unbending in the intact yNhp6A complex is again detected up to ∼35◦C. Microseconds-resolved laser temperaturejump perturbation of the yNhp6a–DNA complex revealed relaxation kinetics that yielded unimolecular DNA bending/unbending rates on timescales of 500 s−1 ms. These data provide the first direct observation of bending/unbending dynamics of DNA in complex with yNhp6A, suggesting a bind-then-bend mechanism for this protein

    Ultraviolet Fixed Points in Gauge and SUSY Field Theories in Extra Dimensions

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    We consider gauge field theories in D>4D>4 following the Wilson RG approach and show that they possess the ultraviolet fixed points where the gauge coupling is dimensionless in any space-time dimension. At the fixed point the anomalous dimensions of the field and vertex operators are known exactly. These fixed points are nonperturbative and correspond to conformal invariant theories. The same phenomenon also happens in supersymmetric theories with the Yukawa type interactions.Comment: LaTeX, 10pp. v2: Comments and references adde

    The one-loop elastic coefficients for the Helfrich membrane in higher dimensions

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    Using a covariant geometric approach we obtain the effective bending couplings for a 2-dimensional rigid membrane embedded into a (2+D)(2+D)-dimensional Euclidean space. The Hamiltonian for the membrane has three terms: The first one is quadratic in its mean extrinsic curvature. The second one is proportional to its Gaussian curvature, and the last one is proportional to its area. The results we obtain are in agreement with those finding that thermal fluctuations soften the 2-dimensional membrane embedded into a 3-dimensional Euclidean space.Comment: 9 page

    Wolf-Livestock Conflict in Montana: Spatial and Temporal Factors Influencing Livestock Loss

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    Successful wolf (Canis lupus) recovery in Montana has brought with it some negative impacts on livestock producers in certain areas and time periods.  We assessed the spatial and temporal patterns of wolf depredations on livestock in Montana at a broad, statewide scale during the past decade (2005–2014).  These analyses highlighted areas of concentrated and consistent wolf-livestock conflicts, such that, for example, 50% of the statewide conflicts occur in 5% of the state.  We then used generalized linear mixed-models to test covariates potentially predictive of both conflict presence (zero vs. non-zero depredation events) and conflict severity (number of events given at least 1), including the assessment of lethal controls and hunter harvest as tools to reduce conflicts.  Using administrative hunting districts (HDs) as the unit of analysis, we found that conflict presence increased for HD-years with wolves present (P<0.001), higher wolf pack densities (P=0.006), higher livestock densities (P<0.001), and intermediate proportionate areas of agricultural land (P<0.001).  HDs with depredations the previous year were more likely to continue having them (P<0.001), though lethal removal of wolves significantly reduced this effect (P=0.038).  Direct effects of wolf hunter harvest were shown to marginally (P=0.152) reduce year-to-year conflicts, but indirect effects of harvest would also be expected given its role in determining wolf numbers, a primary driver of conflicts.  Minimizing livestock losses is a top priority for successful wolf management, and these results shed light on the broad-scale patterns behind chronic problems and the tools used to address them

    Ordered phase and scaling in ZnZ_n models and the three-state antiferromagnetic Potts model in three dimensions

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    Based on a Renormalization-Group picture of ZnZ_n symmetric models in three dimensions, we derive a scaling law for the ZnZ_n order parameter in the ordered phase. An existing Monte Carlo calculation on the three-state antiferromagnetic Potts model, which has the effective Z6Z_6 symmetry, is shown to be consistent with the proposed scaling law. It strongly supports the Renormalization-Group picture that there is a single massive ordered phase, although an apparently rotationally symmetric region in the intermediate temperature was observed numerically.Comment: 5 pages in REVTEX, 2 PostScript figure
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