247 research outputs found

    Carbon Removal and Optoelectronic Property Tuning in Copper Arsenic Sulfide Thin Films through Ligand Exchange and Alloying

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    Solution processed thin film solar cells are attractive alternatives to conventional energy sources due to low waste generation, flexibility in substrate choice, and scalability. The novel semiconductor Cu3AsS4 in the enargite phase has a near ideal band gap of 1.4 eV and has earth abundant constituent elements; yet single-junction solar cells have yielded low efficiencies due to a secondary carbonaceous phase present, among other issues. This carbonaceous phase may be eliminated by exchanging the carbonaceous ligands with molecular metal chalcogenides. To characterize the ligand exchanged particles, UV-Vis-NIR spectroscopy, Raman spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy were used. Heat treatments of these nanoparticles yielded films with no residual carbonaceous phase. This, along with the control over properties such as the band gap, will draw attention to the material system and allow for further optimization for the use of the Cu-As-S material system in photovoltaic applications

    Rigorous QCD Predictions for Decays of P-Wave Quarkonia

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    Rigorous QCD predictions for decay rates of the P-wave states of heavy quarkonia are presented. They are based on a new factorization theorem which is valid to leading order in the heavy quark velocity and to all orders in the running coupling constant of QCD. The decay rates for all four P states into light hadronic or electromagnetic final states are expressed in terms of two phenomenological parameters, whose coefficients are perturbatively calculable. Logarithms of the binding energy encountered in previous perturbative calculations of P-wave decays are factored into a phenomenological parameter that is related to the probability for the heavy quark-antiquark pair to be in a color-octet S-wave state. Applying these predictions to charmonium, we use measured decay rates for the \chione and \chitwo to predict the decay rates of the \chizero and hch_c.Comment: 13 page

    Sound archaeology: terminology, Palaeolithic cave art and the soundscape

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    This article is focused on the ways that terminology describing the study of music and sound within archaeology has changed over time, and how this reflects developing methodologies, exploring the expectations and issues raised by the use of differing kinds of language to define and describe such work. It begins with a discussion of music archaeology, addressing the problems of using the term ‘music’ in an archaeological context. It continues with an examination of archaeoacoustics and acoustics, and an emphasis on sound rather than music. This leads on to a study of sound archaeology and soundscapes, pointing out that it is important to consider the complete acoustic ecology of an archaeological site, in order to identify its affordances, those possibilities offered by invariant acoustic properties. Using a case study from northern Spain, the paper suggests that all of these methodological approaches have merit, and that a project benefits from their integration

    Clubbing masculinities: Gender shifts in gay men's dance floor choreographies

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    This is an Author's Accepted Manuscript of an article published in Journal of Homosexuality, 58(5), 608-625, 2011 [copyright Taylor & Francis], available online at: http://www.tandfonline.com/10.1080/00918369.2011.563660This article adopts an interdisciplinary approach to understanding the intersections of gender, sexuality, and dance. It examines the expressions of sexuality among gay males through culturally popular forms of club dancing. Drawing on political and musical history, I outline an account of how gay men's gendered choreographies changed throughout the 1970s, 80s, and 90s. Through a notion of “technologies of the body,” I situate these developments in relation to cultural levels of homophobia, exploring how masculine expressions are entangled with and regulated by musical structures. My driving hypothesis is that as perceptions of cultural homophobia decrease, popular choreographies of gay men's dance have become more feminine in expression. Exploring this idea in the context of the first decade of the new millennium, I present a case study of TigerHeat, one of the largest weekly gay dance club events in the United States

    Algebraic Models of Hadron Structure II. Strange Baryons

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    The algebraic treatment of baryons is extended to strange resonances. Within this framework we study a collective string-like model in which the radial excitations are interpreted as rotations and vibrations of the strings. We derive a mass formula and closed expressions for strong and electromagnetic decay widths and use these to analyze the available experimental data.Comment: 60 pages, 8 figures, 30 tables, Annals of Physics (N.Y.), in pres

    EVALUATING THE EFFECTS OF MONENSIN OVERDOSE IN DAIRY CATTLE

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    Monensin is approved as a feed additive by the FDA Center for Veterinary Medicine to increase milk production efficiency in lactating dairy cattle. To assess the effects of a gross error in mixing monensin into cattle feed, a 10-fold overdose was given for three consecutive days to naĂŻve cows as well as cows previously dosed with monensin within the label range. Cows were evaluated during the overdose and for a subsequent 4 week observation period. Physiological variables were analyzed, including dry matter intake, body weight, body condition score, and serum chemistry profile. Production variables were analyzed, including milk yield and milk composition. Cows were blocked according to pre-treatment milk output, days in milk, and body condition. Results were analyzed using linear mixed model methodology with a baseline covariate. The study provided information for the veterinarian and the dairy farmer for determining whether an overdose may have occurred, for assessing the prognosis, and for deciding whether to continue feeding monensin immediately following an overdose

    Spin Effects in Two Quark System and Mixed States

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    Based on the numeric solution of a system of coupled channels for vector mesons (SS- and DD-waves mixing) and for tensor mesons (PP- and FF-waves mixing) mass spectrum and wave functions of a family of vector mesons qqˉq\bar{q} in triplet states are obtained. The calculations are performed using a well known Cornell potential with a mixed Lorentz-structure of the confinement term. The spin-dependent part of the potential is taken from the Breit-Fermi approach. The effect of singular terms of potential is considered in the framework of the perturbation theory and by a configuration interaction approach (CIA), modified for a system of coupled equations. It is shown that even a small contribution of the DD-wave to be very important at the calculation of certain characteristics of the meson states.Comment: 12 pages, LaTe

    On the Particle Data Group evaluation of Psi' and chi_c Branching Ratios

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    I propose a new evaluation of ψâ€Č(2S)\psi'(2S) and χc(1P)\chi_c(1P) branching ratios which avoids the correlations affecting the current Particle Data Group evaluation. These correlations explain the apparent technique-dependent discrepancies between the available determinations of the B(χc(1P)→ppˉ){\cal B}(\chi_c(1P)\to p\bar p) and Γ(χc(1P)→γγ)\Gamma(\chi_c(1P)\to \gamma\gamma) under the hypotesis that the current values of the ψâ€Č(2S)→χc(1P)Îł\psi'(2S)\to\chi_c(1P)\gamma branching ratios are overestimated. In the process I also noticed that Particle Data Group has not restated many of the older measurements, when necessary, for the new value of B(J/ψ→l+l−){\cal B}(J/\psi\to l^+l^-), which significantly affects the evaluation of some relevant ψâ€Č(2S)\psi'(2S) and χc(1P)\chi_c(1P) exclusive branching ratios.Comment: 13 pages. Revised version. Submitted to Phys. Rev.

    Identification of the Pr1 Gene Product Completes the Anthocyanin Biosynthesis Pathway of Maize

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    In maize, mutations in the pr1 locus lead to the accumulation of pelargonidin (red) rather than cyanidin (purple) pigments in aleurone cells where the anthocyanin biosynthetic pathway is active. We characterized pr1 mutation and isolated a putative F3â€ČH encoding gene (Zmf3â€Čh1) and showed by segregation analysis that the red kernel phenotype is linked to this gene. Genetic mapping using SNP markers confirms its position on chromosome 5L. Furthermore, genetic complementation experiments using a CaMV 35S::ZmF3â€ČH1 promoter–gene construct established that the encoded protein product was sufficient to perform a 3â€Č-hydroxylation reaction. The Zmf3â€Čh1-specific transcripts were detected in floral and vegetative tissues of Pr1 plants and were absent in pr1. Four pr1 alleles were characterized: two carry a 24 TA dinucleotide repeat insertion in the 5â€Č-upstream promoter region, a third has a 17-bp deletion near the TATA box, and a fourth contains a Ds insertion in exon1. Genetic and transcription assays demonstrated that the pr1 gene is under the regulatory control of anthocyanin transcription factors red1 and colorless1. The cloning and characterization of pr1 completes the molecular identification of all genes encoding structural enzymes of the anthocyanin pathway of maize

    Radiative decays: a new flavour filter

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    Radiative decays of the 13D11^3D_1 orbital excitations of the ρ\rho, ω\omega and ϕ\phi to the scalars f0(1370)f_0(1370), f0(1500)f_0(1500) and f0(1710)f_0(1710) are shown to provide a flavour filter, clarifying the extent of glueball mixing in the scalar states. A complementary approach to the latter is provided by the radiative decays of the scalar mesons to the ground-state vectors ρ\rho, ω\omega and ϕ\phi. Discrimination among different mixing scenarios is strong.Comment: 12 pages, 1 table, 0 figure
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