13,268 research outputs found

    Local Operator Multipliers and Positivity

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    We establish an unbounded version of Stinespring's Theorem and a lifting result for Stinespring representations of completely positive modular maps defined on the space of all compact operators. We apply these results to study positivity for Schur multipliers. We characterise positive local Schur multipliers, and provide a description of positive local Schur multipliers of Toeplitz type. We introduce local operator multipliers as a non-commutative analogue of local Schur multipliers, and obtain a characterisation that extends earlier results concerning operator multipliers and local Schur multipliers. We provide a description of the positive local operator multipliers in terms of approximation by elements of canonical positive cones.Comment: 31 page

    Constraints on the sound speed of dark energy

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    We have studied constraints on the equation of state, ww, and speed of sound, c_s, of the dark energy from a joint analysis of data from the cosmic microwave background, large scale structure and type-Ia supernovae. We find that current observations have no significant sensitivity to c_s. However, there is a slight difference between models in which there are no dark energy perturbations and models in which dark energy behaves as a fluid. Assuming that there are no dark energy perturbations shifts the allowed region for ww to slightly higher values. At present models with and without dark energy perturbations provide roughly equally good fits to observations, but the difference is potentially important for future parameter estimations. Finally, we have also performed error forecasts for future measurements of c_s.Comment: 9 pages, 6 figures, Revte

    The development of a mapping tool for the evaluation of building systems for future climate scenarios on European scale

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    The paper presents a tool for the mapping of the performance of building systems on European scale for different (future) time periods. The tool is to use for users and be applicable for different building systems. Users should also be able to use a broad range of climate parameters to assess the influence of climate change on these climatic parameters. Also should the calculation time be reasonable short. The mapping tool is developed in MATLAB, which can be used by other users for their own studies.Comment: 21 pages, 24 figures, pre-conferenc

    Effects of lasalocid and protein degradability on growth and development of Holstein replacement heifers

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    Two experiments were conducted to examine effects of ionophores on body composition in replacement heifers. In experiment 1, 32 Holstein heifers (250 kg initial BW) were assigned randomly to a 2 x 2 factorial arrangement of low undegradable protein in concentrate (L, 30% of CP) vs high undegradable protein (H, 38% of CP) and lasalocid (0 or 200 mg/hd/d). Animals were housed in an open barn in 8 pens of 4 animals and fed 12.7 kg/pen/d of experimental concentrate once daily with medium quality fescue hay for ad libitum consumption. Body measurements were taken every 28 d while ultrasonic fat thickness (F) and muscle depth (M), urea space (US), body fat % (BF), body protein % (BP) and coccidia (C) were measured every 84 d. There were no significant differences (P \u3c.05) in dry matter intake, feed efficiency, weight gain, height, length, hook width, forearm length, US, BF and C; however, heifers fed LO and H200 had decreased body circumference (BC), F, M and BP. Means for LO, L200,, HO and H200 were: BC (cm), 173.3, 174.6, 177.3, 171.6; F (mm), 7.4, 8.5, 8.7, 8.0; M (mm), 54.1, 57.3, 56.3, 53.9; BP, 17.9, 18.1, 18.2, 18.0. Experiment 2 utilized 20 Holstein heifers assigned randomly to 1 of 2 experimental supplements containing 0 or 200 mg/hd/d lasalocid. Animals were placed on 9.7 ha of permanent fescue divided by portable electric fence and offered 13.6 kg of cracked corn and 5.9 kg of supplement/group/d once daily. Body measurements, F, M, US, BF, BP and C were measured as in experiment 1. There were no significant differences (P \u3c.05) in body measurements, weight gain, F, US, BF, BP; however, heifers fed lasalocid had decreased (P \u3c .05) coccidia and M. Means for 0 and 200 mg/hd/d lasalocid were: C (oocyst/g), 60.8, 36.6; M (mm), 52.5, 49.0. Data from both experiments suggest that lasalocid did not affect rate or composition of body gain in heifers weighing 250 to 430 kg

    Changes in Sexual Risk Perception and Risk Taking Among Urban African American Adolescents

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    Background: Adolescents and young adults aged 15 to 24 acquire nearly half of all new STDs in the United States, yet they represent only 25% of the sexually active population. Young men and women in this age group have the highest rates of chlamydia, gonorrhea, and syphilis, especially in the African American population. Adolescent risk factors include having a history of pregnancy or STDs, being arrested or incarcerated, substance abuse, early sexual debut and having 4 or more lifetime sexual partners. Protective behaviors such as parental involvement, school enrollment, and consistent condom use have been associated with decreased incidence of STDs. The purpose of this study is to observe changes in adolescent behaviors and experiences that are known risk factors for acquiring sexually transmitted diseases. The aim is to identify the time at which STD prevention interventions may be administered most effectively. In addition, the study aims to identify relevant themes and content that may be useful in creating interventions targeted to different age groups and genders. Methods: This study utilizes primary data collected between 1999 and 2003 by Dr. Rothenberg and colleagues for a community-based network study of low-income African American adolescents living in a working class neighborhood in Southwest Atlanta. Two descriptive analyses were conducted: a period analysis in which all participants ages 15 to 18 who completed any or all of three interviews were included; and a cohort analysis, which included only participants who completed three interviews and who were 15, 16, 17 or 18 years of age at the time of the first interview. Univariate analysis was used to describe each variable and the resulting frequencies and percentages were reported. Results: In both period and cohort analyses, higher proportions of older adolescents (ages 17 and 18) reported engaging in risky behaviors including drinking alcohol, using marijuana, having sex and having multiple sexual partners, compared to younger adolescents (ages 15 and 16). Males reported higher proportions of engaging in risky behaviors than females, but also higher proportions of condom use. The proportion of participants diagnosed with one or more STDs decreased at each interview. In the cohort analysis, the proportion of participants who perceived their STD risk as “medium” or “high” increased over time. Conclusions: The findings suggest that as adolescents mature they engage in a greater variety of risky behaviors known to have a positive association to STD diagnosis. Period analyses, which have usually been done to study the sexual behaviors of adolescents, may give aberrant results that are clearer when the population is studied as a cohort. Future studies are needed to more precisely identify the period during which adolescents experience rapid changes in their risk behaviors

    Vaginal yeasts in the era of "over the counter" antifungals

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    OBJECTIVE: To establish whether there has been any rise in the prevalence of non-albicans Candida species isolated from vaginal swabs since the introduction of “over the counter” antifungal treatments. METHOD: A retrospective review looking at all positive vaginal yeast isolates collected from women attending one genitourinary medicine clinic during the 6 year period from 1993 to 1998 inclusive. All positive vaginal yeast isolates were included, regardless of whether or not the patients were symptomatic. Isolates from HIV positive women were excluded from the analysis. RESULT: No increase in non-albicans vaginal yeast isolates was shown during the period studied. The proportion of non-albicans yeasts remained constant at approximately 5% of the total yeasts isolated. The most common non-albicans yeast isolated was C glabrata. CONCLUSION: There is no evidence from this study to suggest that the increasing use of “over the counter” antifungal treatment has selected for atypical, possibly inherently azole resistant, strains of vaginal yeasts in HIV seronegative women

    Large-Scale Newscast Computing on the Internet

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    Temporal adaptation and anticipation mechanisms in sensorimotor synchronization

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