20,501 research outputs found

    Hoelder Inequalities and QCD Sum-Rule Bounds on the Masses of Light Quarks

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    QCD Laplace Sum-Rules must satisfy a fundamental Hoelder inequality if they are to consistently represent an integrated hadronic spectral function. The Laplace sum-rules of pion currents is shown to violate this inequality unless the uu and dd quark masses are sufficiently large, placing a lower bound on mu+mdm_u+m_d, the SU(2)-invariant combination of the light-quark masses.Comment: 3 pages, latex, write-up of talk presented at DPF 200

    Raising the Bar on Training at Valparaiso University

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    We have recently overhauled our IT training program that we offer our students, faculty and staff. In the past, the training program consisted of sessions about changes to campus systems or sessions related to very specific software uses such as mail merge or tables. Users can now expect that training will be more than software use and how-to’s. We have started looking at ways to enhance our clients overall use of campus technology. As we examined ways to better serve our campus community, we engaged in qualitative observations in many areas. We examined how our graduate students were using technology to collaborate. The faculty were observed by our training staff to see how they were employing campus technology in courses and integrating technology into their assignments given to students. We interviewed our Help Desk Student Consultants to see what they observed as major training goals throughout the campus based on their interactions with clients. Upon completion of our observations, we outline our course development plans for increasing technology integration and full use of our campus technology offerings to further our mission of enhancing learning, teaching and job function through technology. Our goal is to reach beyond the software functionality and take our clients to the apex of relevance and application

    Mental health and developmental disorders in infancy and early childhood. The PDM-2

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    We provide a general introduction to the theoretical and empirical sources informing the development of the Infancy and Early Childhood Section (IEC) of the second edition of the Psychodynamic Diagnostic Manual (PDM-2). We offer a brief exploration of the evolution of developmental psychoanalysis and its applications to infant mental health, along with an example of applying the IEC framework to clinical and developmental data from a longitudinal study based on developmental and psychodynamic principles. This article illustrates the evolution of theory in the context of interdisciplinary integration and explores its implications for diagnosis and clinical formulatio

    Fractionation of nitrogen isotopes by animals: a further complication to the use of variations in the natural abundance of ¹⁵N for tracer studies

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    A study of the fractionation of nitrogen isotopes in the diet by cattle is described and the results discussed. Compared with the diet, urine had a lower ratio of ¹⁵N to ¹⁴N, but faeces, blood and milk all had a higher ratio. It is argued that the use of natural ¹⁵N as a tracer in grazed ecosystems is more complicated than was at first thought

    Baryonic contributions to e+e- yields in a hydrodynamic model of Pb+Au collisions at the SPS

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    We analyze e+e- yields from matter containing baryons in addition to mesons using a hydrodynamic approach to describe Pb+Au collisions at 158 A GeV/c. We use two distinctly different e+e- production rates to provide contrast. Although the presence of baryons leads to significant enhancement of e+e- emission relative to that from mesons-only matter, the calculated results fall below the data in the range 400 < M/MeV < 600. The calculated results are, however, only 1.3-1.5 standard deviations below the data, which may not be statistically significant.Comment: 4 pages, 4 figures, proceedings of Quark Matter 9

    Denitrification by rhizobia: A possible factor contributing to nitrogen losses from soils

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    The intensive pastoral farming system on which New Zealand animal production is based is almost completely dependent upon the rhizobium-legurne symbiosis for the fixed nitrogen required for pasture production. The average annual fixation has been measured as 184 kg nitrogen/ha in developed lowland pastures Hoglund et cii., 1979 and about 13 kg nitrogen/ha in poorly developed bill country pastures (Grant and Lambert, 1979). From these figures it can be estimated that rhizobia in New Zealand pastures fix in excess of one million tonnes of nitrogen an nually. The current annual application of fertilizer nitrogen to pastures is about 12 500 tonnes (O'Connor, 1979)

    Mineralogy of the Ibitira eucrite and comparison with other eucrites and lunar samples

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    Single crystal X-ray and energy dispersive electron-probe techniques are used to study the mineralogy and track history of Ibitira. The mineralogical features of the Ibitire eucrite are described and examined in relation to data for other eucrites and howardites and lunar samples. The processes which transformed a presumed igneous texture into a more complex one are discussed

    Near-infrared spectroscopy of the very low mass companion to the hot DA white dwarf PG1234+482

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    We present a near-infrared spectrum of the hot (TeffT_{\rm eff} \approx 55,000 K) DA white dwarf PG 1234+482. We confirm that a very low mass companion is responsible for the previously recognised infrared photometric excess. We compare spectra of M and L dwarfs, combined with an appropriate white dwarf model, to the data to constrain the spectral type of the secondary. We find that uncertainties in the 2MASS HKHK photometry of the white dwarf prevent us from distinguishing whether the secondary is stellar or substellar, and assign a spectral type of L0±\pm1 (M9-L1).Therefore, this is the hottest and youngest (106\approx 10^6 yr) DA white dwarf with a possible brown dwarf companion.Comment: 5 pages, 2 figures, accepted by MNRA
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