4,564 research outputs found

    The threat of biological attack: why concern now?

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    The Making of Modern-Day NIL Laws: The Past, Present, and Future of Amateurism and Commercialization in College Sport

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    The purpose of this study was to increase the understanding of state laws governing collegiate student-athletes’ name, image, and likeness (NIL) rights and place the laws within the framework of the NCAA’s historic and current views on amateurism and commercialization. To accomplish such, a content analysis of the 30 existing NIL laws/executive orders was performed to identify trends in the statutes and establish what commonalities and differences exist across states. The analysis found five themes/sections common across state laws (i.e., definitions, basic NIL rules, limitations, disclosures and review processes, agent and representation rules, and required workshops). Moreover, the evaluation revealed the basic NIL rights of student-athletes are uniform across all states. However, the limitations that are placed on them and the processes they must abide by vary from state to state. Current NCAA bylaws were found to coincide with the new state laws, while still maintaining the organization’s desire for amateurism and push to minimize commercialization

    Infinite Layer LaNiO(2): Ni(1+)is not Cu(2+)

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    The Ni ion in LaNiO2_2 has the same formal ionic configuration 3d93d^9 as does Cu in isostructural CaCuO2_2, but it is reported to be nonmagnetic and probably metallic whereas CaCuO2_2 is a magnetic insulator. From ab initio calculations we trace its individualistic behavior to (1) reduced 3d−2p3d-2p mixing due to an increase of the separation of site energies (ϵd−ϵp\epsilon_d - \epsilon_p) of at least 2 eV, and (2) important Ni 3d(3z2−r2)3d(3z^2-r^2) mixing with La 5d(3z2−r2)5d(3z^2-r^2) states that leads to Fermi surface pockets of La 5d5d character that hole-dope the Ni 3d band.Correlation effects do not appear to be large in LaNiO2_2. However, ad hoc increase of the intraatomic repulsion on the Ni site (using the LDA+U method) is found to lead to a novel correlated state: (i) the transition metal d(x2−y2)d(x^2-y^2) and d(3z2−r2)d(3z^2-r^2) states undergo consecutive Mott transitions, (ii) their moments are antialigned leading (ideally) to a "singlet" ion in which there are two polarized orbitals, and (iii) mixing of the upper Hubbard 3d(3z2−r2)3d(3z^2-r^2) band with the La 5d(xy)5d(xy) states leaves considerable transition metal 3d character in a band pinned to the Fermi level. The magnetic configuration is more indicative of a Ni2+^{2+} ion in this limit, although the actual charge changes little with U.Comment: 7 pages, 8 figure

    Spin-ladders with spin gaps: A description of a class of cuprates

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    We investigate the magnetic properties of the Cu-O planes in stoichiometric Srn−1_{n-1}Cun+1_{n+1}O2n_{2n} (n=3,5,7,...) which consist of CuO double chains periodically intergrown within the CuO2_2 planes. The double chains break up the two-dimensional antiferromagnetic planes into Heisenberg spin ladders with nr=12(n−1)n_r=\frac{1}{2}(n-1) rungs and nl=12(n+1)n_l=\frac{1}{2}(n+1) legs and described by the usual antiferromagnetic coupling J inside each ladder and a weak and frustrated interladder coupling J′^\prime. The resulting lattice is a new two-dimensional trellis lattice. We first examine the spin excitation spectra of isolated quasi one dimensional Heisenberg ladders which exhibit a gapless spectra when nrn_r is even and nln_l is odd ( corresponding to n=5,9,...) and a gapped spectra when nrn_r is odd and nln_l is even (corresponding to n=3,7,...). We use the bond operator representation of quantum S=12S=\frac{1}{2} spins in a mean field treatment with self-energy corrections and obtain a spin gap of ≈12J\approx \frac{1}{2} J for the simplest single rung ladder (n=3), in agreement with numerical estimates.Comment: 21 pages, 5 figures upon request, REVTEX, ETH-TH/93-3
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