7,858 research outputs found

    Decoupling Transition I. Flux Lattices in Pure Layered Superconductors

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    We study the decoupling transition of flux lattices in a layered superconductors at which the Josephson coupling J is renormalized to zero. We identify the order parameter and related correlations; the latter are shown to decay as a power law in the decoupled phase. Within 2nd order renormalization group we find that the transition is always continuous, in contrast with results of the self consistent harmonic approximation. The critical temperature for weak J is ~1/B, where B is the magnetic field, while for strong J it is~1/sqrt{B} and is strongly enhanced. We show that renormaliztion group can be used to evaluate the Josephson plasma frequency and find that for weak J it is~1/BT^2 in the decoupled phase.Comment: 14 pages, 5 figures. New sections III, V. Companion to following article on "Decoupling and Depinning II: Flux lattices in disordered layered superconductors

    Transverse instabilities of stripe domains in magnetic thin films with perpendicular magnetic anisotropy

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    Stripe domains are narrow, elongated, reversed regions that exist in magnetic materials with perpendicular magnetic anisotropy. Stripe domains appear as a pair of domain walls that can exhibit topology with a nonzero chirality. Recent experimental and numerical investigations identify an instability of stripe domains in the long direction as a means of nucleating isolated magnetic skyrmions. Here, the onset and nonlinear evolution of transverse instabilities for a dynamic stripe domain known as the bion stripe are investigated. Both non-topological and topological variants of the bion stripe are shown to exhibit a long-wavelength transverse instability with different characteristic features. In the former, small transverse variations in the stripe's width lead to a neck instability that eventually pinches the non-topological stripe into a chain of two-dimensional breathers composed of droplet soliton pairs. In the latter case, small variations in the stripe's center results in a snake instability whose topological structure leads to the nucleation of dynamic magnetic skyrmions and antiskyrmions as well as perimeter-modulated droplets. Quantitative, analytical predictions for both the early, linear evolution and the long-time, nonlinear evolution are achieved using an averaged Lagrangian approach that incorporates both exchange (dispersion) and anisotropy (nonlinearity). The method of analysis is general and can be applied to other filamentary structures.Comment: 8 figures, 13 page

    Cookies for children (1964)

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    Pages six and seven are missing.Cookies are favorites with juSt about everybody especially hungty boys and girls juSt home from school or a session of play. Such a popular food needs to be good for you as well as good to ear. Many cookies are high in carbohydrates, sugar, and fat, and supply few nutrienrs other than calories. Recipes in this bulletin have been developed to make cookies tasty as well as to contain many nutrients needed for growth; for muscle, bone, and tooth development; and for general well-being.Cooky ingredients -- General Suggestions. Mixing ; Baking ; Storing ; Freezing -- Cooky recipies. Carrot-raisin ; Fruit ; Golden yellow ; Cereal ; Honey Whole Wheat ; Molasses ginger ; Soft molasses ; Molasses whole wheat ; Peanut butter molasses ; Peanut butter ; Chocolate whole wheat-oatmeal -- Lunch wafers -- Teething cooky -- Recipies using cooky mix -- Basic cooky mix. Raisin drop ; Lemon drops ; Peanut butter ; oatmeal ; Cocoa drop -- Comparision of food nutrients of different cookies ; Aproximate percentage of minimum daily requirements of certain nutrients supplied by selected cookie

    Dividing population genetic distance data with the software Partitioning Optimization with Restricted Growth Strings (PORGS): an application for Chinook salmon (Oncorhynchus tshawytscha), Vancouver Island, British Columbia

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    A new method of finding the optimal group membership and number of groupings to partition population genetic distance data is presented. The software program Partitioning Optimization with Restricted Growth Strings (PORGS), visits all possible set partitions and deems acceptable partitions to be those that reduce mean intracluster distance. The optimal number of groups is determined with the gap statistic which compares PORGS results with a reference distribution. The PORGS method was validated by a simulated data set with a known distribution. For efficiency, where values of n were larger, restricted growth strings (RGS) were used to bipartition populations during a nested search (bi-PORGS). Bi-PORGS was applied to a set of genetic data from 18 Chinook salmon (Oncorhynchus tshawytscha) populations from the west coast of Vancouver Island. The optimal grouping of these populations corresponded to four geographic locations: 1) Quatsino Sound, 2) Nootka Sound, 3) Clayoquot +Barkley sounds, and 4) southwest Vancouver Island. However, assignment of populations to groups did not strictly reflect the geographical divisions; fish of Barkley Sound origin that had strayed into the Gold River and close genetic similarity between transferred and donor populations meant groupings crossed geographic boundaries. Overall, stock structure determined by this partitioning method was similar to that determined by the unweighted pair-group method with arithmetic averages (UPGMA), an agglomerative clustering algorithm

    New data and the hard pomeron

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    New structure-function data are in excellent agreement with the existence of a hard pomeron, with intercept about 1.4. It gives a very economical description of the data. Having fixed 2 parameters from the data for the real-photon cross section σγp\sigma^{\gamma p}, we need just 5 further parameters to fit the data for F2(x,Q2)F_2(x,Q^2) with x≤0.001x\leq 0.001. The available data range from Q2=0.045Q^2=0.045 to 35 GeV2^2. With guesses consistent with dimensional counting for the xx dependences of our three separate terms, the fit extends well to larger xx and to Q2=5000Q^2=5000 GeV2^2. With no additional parameters, it gives a good description of data for the charm structure function F2c(x,Q2)F_2^c(x,Q^2) from Q2=0Q^2=0 to 130 GeV2^2. The two pomerons also give a good description of both the WW and the tt dependence of γp→J/ψp\gamma p\to J/\psi p.Comment: 11 pages, plain tex, with 10 figures embedded using epsf. (Spurious figure removed.

    Archives of the Southern Sociological Society: A Repository of Decisions, Events, and People Affecting Sociology in the Southern United States

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    Since 1958, the Archives of the Southern Sociological Society have been housed in the Special Collections Research Center in the University of Kentucky Libraries. The collection includes official minutes, correspondence, newsletters, membership lists, photographs, and other official documents generated by the Society and dating from the Society\u27s founding in 1935 to the present. These records of historical value have been provided by presidents, secretaries, treasurers, committee chairs, executive officers, and other Society officials so that the Archives may be available to scholars who wish to explore the history of the Society and the development of Sociology in the Southern United States. Drawing on research and sources in the Archives, these seven posters highlight the following topics: planning and establishing the Southern Sociological Society; the first annual meeting (held in 1936 at the Atlanta Biltmore); challenges of developing a racially inclusive organization in the segregated South; stances toward social issues in the early 1960s; changes in emphases and breadth of conference session topics across the decades; photographs highlighting fashion and leadership; and meeting locations and membership numbers

    Direct Determinations of the Redshift Behavior of the Pressure, Energy Density, and Equation of State of the Dark Energy and the Acceleration of the Universe

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    One of the goals of current cosmological studies is the determination of the expansion and acceleration rates of the universe as functions of redshift, and the determination of the properties of the dark energy that can explain these observations. Here the expansion and acceleration rates are determined directly from the data, without the need for the specification of a theory of gravity, and without adopting an a priori parameterization of the form or redshift evolution of the dark energy. We use the latest set of distances to SN standard candles from Riess et al. (2004), supplemented by data on radio galaxy standard ruler sizes, as described by Daly and Djorgovski (2003, 2004). We find that the universe transitions from acceleration to deceleration at a redshift of about 0.4. The standard "concordance model" provides a reasonably good fit to the dimensionless expansion rate as a function of redshift, though it fits the dimensionless acceleration rate as a function of redshift less well. The expansion and acceleration rates are then combined with a theory of gravity to determine the pressure, energy density, and equation of state of the dark energy as functions of redshift. Adopting General Relativity as the correct theory of gravity, the redshift trends for the pressure, energy density, and equation of state of the dark energy out to redshifts of about one are determined, and are found to be generally consistent with the concordance model.Comment: 8 pages, 5 figures. Invited presentation at Coral Gables 200
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