230 research outputs found

    An Analysis of Sportswomen on the Covers and in the Feature Articles of Women's Sport and Fitness Magazine, 1975-1989

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    This is the publisher's official version, which the author obtained permission to share. The article is also available electronically from: http://dx.doi.org/10.1177/019372359201600207.This study analyzes the treatment of athletes in Women's Sports and Fitness between 1975 and 1989. Author, article length, gender, sport, race, and sporting role were assessed for each article; the number of accompanying pictures to each article and the characteristics of those featured in the articles were also tallied. Gender, race, sport, and active or posed status of the individual appearing on the cover were coded. Whites were featured in 92% of the articles, mostly in tennis, running, track, basketball, and golf. Of the 151 covers, 98. 7% showed females with 92% whites and 8% blacks. This magazine, on its covers and in its feature articles, changed its emphasis from reporting on traditional sports and competitions to focusing on fitness activities for all women

    Reply to the comment by Jacobs and Thorpe

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    Reply to a comment on "Infinite-Cluster geometry in central-force networks", PRL 78 (1997), 1480. A discussion about the order of the rigidity percolation transition.Comment: 1 page revTe

    Failure Probabilities and Tough-Brittle Crossover of Heterogeneous Materials with Continuous Disorder

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    The failure probabilities or the strength distributions of heterogeneous 1D systems with continuous local strength distribution and local load sharing have been studied using a simple, exact, recursive method. The fracture behavior depends on the local bond-strength distribution, the system size, and the applied stress, and crossovers occur as system size or stress changes. In the brittle region, systems with continuous disorders have a failure probability of the modified-Gumbel form, similar to that for systems with percolation disorder. The modified-Gumbel form is of special significance in weak-stress situations. This new recursive method has also been generalized to calculate exactly the failure probabilities under various boundary conditions, thereby illustrating the important effect of surfaces in the fracture process.Comment: 9 pages, revtex, 7 figure

    Infinite-cluster geometry in central-force networks

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    We show that the infinite percolating cluster (with density P_inf) of central-force networks is composed of: a fractal stress-bearing backbone (Pb) and; rigid but unstressed ``dangling ends'' which occupy a finite volume-fraction of the lattice (Pd). Near the rigidity threshold pc, there is then a first-order transition in P_inf = Pd + Pb, while Pb is second-order with exponent Beta'. A new mean field theory shows Beta'(mf)=1/2, while simulations of triangular lattices give Beta'_tr = 0.255 +/- 0.03.Comment: 6 pages, 4 figures, uses epsfig. Accepted for publication in Physical Review Letter

    Current-voltage characteristics of diluted Josephson-junction arrays: scaling behavior at current and percolation threshold

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    Dynamical simulations and scaling arguments are used to study the current-voltage (IV) characteristics of a two-dimensional model of resistively shunted Josephson-junction arrays in presence of percolative disorder, at zero external field. Two different limits of the Josephson-coupling concentration pp are considered, where pcp_c is the percolation threshold. For pp >> pcp_c and zero temperature, the IV curves show power-law behavior above a disorder dependent critical current. The power-law behavior and critical exponents are consistent with a simple scaling analysis. At pcp_c and finite temperature TT, the results show the scaling behavior of a T=0 superconducting transition. The resistance is linear but vanishes for decreasing TT with an apparent exponential behavior. Crossover to non-linearity appears at currents proportional to % T^{1+\nu_T}, with a thermal-correlation length exponent νT\nu_T consistent with the corresponding value for the diluted XY model at pcp_c.Comment: Revtex, 9 postscript pages, to appear in Phys. Rev.

    Precise determination of the bond percolation thresholds and finite-size scaling corrections for the s.c., f.c.c., and b.c.c. lattices

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    Extensive Monte-Carlo simulations were performed to study bond percolation on the simple cubic (s.c.), face-centered cubic (f.c.c.), and body-centered cubic (b.c.c.) lattices, using an epidemic kind of approach. These simulations provide very precise values of the critical thresholds for each of the lattices: pc(s.c.) = 0.248 812 6(5), pc(f.c.c.) = 0.120 163 5(10), and pc(b.c.c.) = 0.180 287 5(10). For p close to pc, the results follow the expected finite-size and scaling behavior, with values for the Fisher exponent tautau (2.189(2)), the finite-size correction exponent omegaomega (0.64(2)), and the scaling function exponent sigmasigma (0.445(1)) confirmed to be universal.Comment: 16 pgs, 7 figures, LaTeX, to be published in Phys. Rev.

    Towards a first principles description of phonons in Ni50_{50}Pt50_{50} disordered alloys: the role of relaxation

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    Using a combination of density-functional perturbation theory and the itinerant coherent potential approximation, we study the effects of atomic relaxation on the inelastic incoherent neutron scattering cross sections of disordered Ni50_{50}Pt50_{50} alloys. We build on previous work, where empirical force constants were adjusted {\it ad hoc} to agree with experiment. After first relaxing all structural parameters within the local-density approximation for ordered NiPt compounds, density-functional perturbation theory is then used to compute phonon spectra, densities of states, and the force constants. The resulting nearest-neighbor force constants are first compared to those of other ordered structures of different stoichiometry, and then used to generate the inelastic scattering cross sections within the itinerant coherent potential approximation. We find that structural relaxation substantially affects the computed force constants and resulting inelastic cross sections, and that the effect is much more pronounced in random alloys than in ordered alloys.Comment: 8 pages, 3 eps figures, uses revtex

    Experimental evidence of a fractal dissipative regime in high-T_c superconductors

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    We report on our experimental evidence of a substantial geometrical ingredient characterizing the problem of incipient dissipation in high-T_c superconductors(HTS): high-resolution studies of differential resistance-current characteristics in absence of magnetic field enabled us to identify and quantify the fractal dissipative regime inside which the actual current-carrying medium is an object of fractal geometry. The discovery of a fractal regime proves the reality and consistency of critical-phenomena scenario as a model for dissipation in inhomogeneous and disordered HTS, gives the experimentally-based value of the relevant finite-size scaling exponent and offers some interesting new guidelines to the problem of pairing mechanisms in HTS.Comment: 5 pages, 3 figures, RevTex; Accepted for publication in Physical Review B; (figures enlarged

    Probability Distribution of the Shortest Path on the Percolation Cluster, its Backbone and Skeleton

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    We consider the mean distribution functions Phi(r|l), Phi(B)(r|l), and Phi(S)(r|l), giving the probability that two sites on the incipient percolation cluster, on its backbone and on its skeleton, respectively, connected by a shortest path of length l are separated by an Euclidean distance r. Following a scaling argument due to de Gennes for self-avoiding walks, we derive analytical expressions for the exponents g1=df+dmin-d and g1B=g1S-3dmin-d, which determine the scaling behavior of the distribution functions in the limit x=r/l^(nu) much less than 1, i.e., Phi(r|l) proportional to l^(-(nu)d)x^(g1), Phi(B)(r|l) proportional to l^(-(nu)d)x^(g1B), and Phi(S)(r|l) proportional to l^(-(nu)d)x^(g1S), with nu=1/dmin, where df and dmin are the fractal dimensions of the percolation cluster and the shortest path, respectively. The theoretical predictions for g1, g1B, and g1S are in very good agreement with our numerical results.Comment: 10 pages, 3 figure
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