15,289 research outputs found

    Eliminating the CPT-Odd f Coefficient from the Lorentz-Violating Standard Model Extension

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    The fermionic f coefficient in the Lorentz-violating standard model extension presents a puzzle. Thus far, no observable quantity that depends upon f has ever been found. We show that this is because f is actually unnecessary. It has absolutely no effects at leading order and can be completely absorbed into other coefficients of the theory by a redefinition of the field.Comment: 12 page

    The impact of prior information on estimates of disease transmissibility using Bayesian tools

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    The basic reproductive number (R₀) and the distribution of the serial interval (SI) are often used to quantify transmission during an infectious disease outbreak. In this paper, we present estimates of R₀ and SI from the 2003 SARS outbreak in Hong Kong and Singapore, and the 2009 pandemic influenza A(H1N1) outbreak in South Africa using methods that expand upon an existing Bayesian framework. This expanded framework allows for the incorporation of additional information, such as contact tracing or household data, through prior distributions. The results for the R₀ and the SI from the influenza outbreak in South Africa were similar regardless of the prior information (R0 = 1.36-1.46, μ = 2.0-2.7, μ = mean of the SI). The estimates of R₀ and μ for the SARS outbreak ranged from 2.0-4.4 and 7.4-11.3, respectively, and were shown to vary depending on the use of contact tracing data. The impact of the contact tracing data was likely due to the small number of SARS cases relative to the size of the contact tracing sample

    A revision of the genus Gymnetina Casey, 1915 (Coleoptera: Scarabaeidae: Cetoniinae: Gymnetini)

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    The genus Gymnetina Casey (Coleoptera: Scarabaeidae: Cetoniinae: Gymnetini) is redescribed and revised. Three new species and one new subspecies are described: G. borealis Warner and Ratcliffe, G. grossepunctata Ratcliffe and Warner, G. howdeni Warner and Ratcliffe, and G. cretacea sundbergi Warner and Ratcliffe. Gymnetina salicis (Bates), new status, is removed from synonymy with G. cretacea (LeConte), and G. alboscripta (Janson) is transferred from Gymnetis MacLeay to Gymnetina becoming Gymnetina alboscripta (Janson), new combination. Redescriptions of previously known species, a key for identification, and illustrations of the six species are provided. A brief biogeographical analysis suggests that ancestral taxa dispersed northwards from Guatemala and Mexico to the southwestern United States

    Sparse domination results for compactness on weighted spaces

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    By means of appropriate sparse bounds, we deduce compactness on weighted Lp(w)L^p(w) spaces, 1<p<1<p<\infty, for all Calder\'on-Zygmund operators having compact extensions on L2(Rn)L^2(\mathbb{R}^n). Similar methods lead to new results on boundedness and compactness of Haar multipliers on weighted spaces. In particular, we prove weighted bounds for weights in a class strictly larger than the typical ApA_p class.Comment: 25 page

    Factors Influencing College Selection by NCAA Division III Men's Basketball Players

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    National Collegiate Athletic Association (NCAA) Division III basketball, coaches are often faced with the challenge of stretching resources to successfully recruit players who will represent the institution without the benefit of athletic scholarships.&nbsp;Having a better grasp of the factors that influence the college selection of NCAA Division III players might assist these coaches in more efficiently maximizing their resources. The purposes of this study were to (a) examine specific factors which influence why DIII basketball players made their choice to attend a particular school, (b) determine if there were differences based upon the type of school attended, and (c) examine whether there were categorical factors that differed on the basis of a players recruitment, year in school, race/ethnicity, playing status, or financial aid status. &nbsp;&nbsp;Using the revised Influential Factors Survey for Student Athletes (IFSSA-R; Pauline, 2010), 503 DIII men’s basketball players were surveyed.&nbsp;Participant responses indicated that ‘career opportunities’ was the most vital item affecting college selection. With regard to the five categorical factors (academic, athletic, coaching staff, financial aid, and social atmosphere) academic factors were also found to be important.&nbsp;&nbsp; Analyses revealed significant (p &lt; .05) differences as determined by type of school for the athletic, academic, and financial aid subscales.&nbsp; Results of the study will provide useful information for DIII men’s basketball coaches and college administrators throughout various points in the recruiting and college selection process.&nbsp; Keywords: coaching, recruiting, basketball, NCAA Division III, college selectio

    On the origin and application of the Bruggeman correlation for analysing transport phenomena in electrochemical systems

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    The widely used Bruggeman equations correlate tortuosity factors of porous media with their porosity. Finding diverse application from optics to bubble formation, it received considerable attention in fuel cell and battery research, recently. The ability to estimate tortuous mass transport resistance based on porosity alone is attractive, because direct access to the tortuosity factors is notoriously difficult. The correlation, however, has limitations, which are not widely appreciated owing to the limited accessibility of the original manuscript. We retrace Bruggeman's derivation, together with its initial assumptions, and comment on validity and limitations apparent from the original work to offer some guidance on its use

    The limitations of Slater's element-dependent exchange functional from analytic density functional theory

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    Our recent formulation of the analytic and variational Slater-Roothaan (SR) method, which uses Gaussian basis sets to variationally express the molecular orbitals, electron density and the one body effective potential of density functional theory, is reviewed. Variational fitting can be extended to the resolution of identity method,where variationality then refers to the error in each two electron integral and not to the total energy. It is proposed that the appropriate fitting functions be charge neutral and that all ab initio energies be evaluated using two-center fits of the two-electron integrals. The SR method has its root in the Slater's Xalpha method and permits an arbitrary scaling of the Slater-Gaspar-Kohn-Sham exchange-correlation potential around each atom in the system. Of several ways of choosing the scaling factors (Slater's exchange parameters), two most obvious are the Hartree-Fock (HF), alpha_HF, values and the exact atomic, alpha_EA, values. The performance of this simple analytic model with both sets for atomization energies of G2 set of 148 molecules is better than the local density approximation or the HF theory, although the errors in atomization energy are larger than the target chemical accuracy. To improve peformance for atomization energies, the SR method is reparametrized to give atomization energies of 148 molecules to be comparbale to those obtained by one of the most widely used generalized gradient approximations. The mean absolute error in ionization potentials of 49 atoms and molecules is about 0.5 eV and that in bond distances of 27 molecules is about 0.02 Angstrom. The overall good performance of the computationally efficient SR method using any reasonable set of alpha values makes it a promising method for study of large systems.Comment: 33 pages, Uses RevTex, to appear in The Journal of Chemical Physic

    Model Atmospheres for Irradiated Stars in pre-Cataclysmic Variables

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    Model atmospheres have been computed for M dwarfs that are strongly irradiated by nearby hot companions. A variety of primary and secondary spectral types are explored in addition to models specific to four known systems: GD 245, NN Ser, AA Dor, and UU Sge. This work demonstrates that a dramatic temperature inversion is possible on at least one hemisphere of an irradiated M dwarf and the emergent spectrum will be significantly different from an isolated M dwarf or a black body flux distribution. For the first time, synthetic spectra suitable for direct comparison to high-resolution observations of irradiated M dwarfs in non-mass transferring post-common envelope binaries are presented. The effects of departures from local thermodynamic equilibrium on the Balmer line profiles are also discussed.Comment: Accepted for publication in ApJ; 12 pages, 10 figure
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