3,062 research outputs found

    WIMP Dark Matter and the QCD Equation of State

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    Weakly Interacting Massive Particles (WIMPs) of mass m freeze out at a temperature T_f ~ m/25, i.e. in the range 400 MeV -- 40 GeV for a particle in the typical mass range 10 -- 1000 GeV. The WIMP relic density, which depends on the effective number of relativistic degrees of freedom at T_f, may be measured to better than 1% by Planck, warranting comparable theoretical precision. Recent theoretical and experimental advances in the understanding of high temperature QCD show that the quark gluon plasma departs significantly from ideal behaviour up to temperatures of several GeV, necessitating an improvement of the cosmological equation of state over those currently used. We discuss how this increases the relic density by approximately 1.5 -- 3.5% in benchmark mSUGRA models, with an uncertainly in the QCD corrections of 0.5 -- 1 %. We point out what further work is required to achieve a theoretical accuracy comparable with the expected observational precision, and speculate that the effective number of degrees of freedom at T_f may become measurable in the foreseeable future.Comment: 4pp, 2figs. More info including Matlab scripts used to generate equation of state curves at http://www.pact.cpes.sussex.ac.uk/arXiv/hep-ph/0501232

    Determination of some dominant parameters of the global dynamic sea surface topography from GEOS-3 altimetry

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    The 1977 altimetry data bank is analyzed for the geometrical shape of the sea surface expressed as surface spherical harmonics after referral to the higher reference model defined by GEM 9. The resulting determination is expressed as quasi-stationary dynamic SST. Solutions are obtained from different sets of long arcs in the GEOS-3 altimeter data bank as well as from sub-sets related to the September 1975 and March 1976 equinoxes assembled with a view to minimizing seasonal effects. The results are compared with equivalent parameters obtained from the hydrostatic analysis of sporadic temperature, pressure and salinity measurements of the oceans and the known major steady state current systems with comparable wavelengths. The most clearly defined parameter (the zonal harmonic of degree 2) is obtained with an uncertainty of + or - 6 cm. The preferred numerical value is smaller than the oceanographic value due to the effect of the correction for the permanent earth tide. Similar precision is achieved for the zonal harmonic of degree 3. The precision obtained for the fourth degree zonal harmonic reflects more closely the accuracy expected from the level of noise in the orbital solutions

    Extrapolation of Galactic Dust Emission at 100 Microns to CMBR Frequencies Using FIRAS

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    We present predicted full-sky maps of submillimeter and microwave emission from the diffuse interstellar dust in the Galaxy. These maps are extrapolated from the 100 micron emission and 100/240 micron flux ratio maps that Schlegel, Finkbeiner, & Davis (1998; SFD98) generated from IRAS and COBE/DIRBE data. Results are presented for a number of physically plausible emissivity models. We find that no power law emissivity function fits the FIRAS data from 200 - 2100 GHz. In this paper we provide a formalism for a multi-component model for the dust emission. A two-component model with a mixture of silicate and carbon-dominated grains (motivated by Pollack et al., 1994}) provides a fit to an accuracy of about 15% to all the FIRAS data over the entire high-latitude sky. Small systematic differences are found between the atomic and molecular phases of the ISM. Our predictions for the thermal (vibrational) emission from Galactic dust at \nu < 3000 GHz are available for general use. These full-sky predictions can be made at the DIRBE resolution of 40' or at the higher resolution of 6.1 arcmin from the SFD98 DIRBE-corrected IRAS maps.Comment: 48 pages, AAS LaTeX, 6 figures, ApJ (accepted). Data described in the text, as well as 4 additional figures, are available at http://astro.berkeley.edu/dus

    The prevalences of Salmonella Genomic Island 1 variants in human and animal Salmonella Typhimurium DT104 are distinguishable using a Bayesian approach

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    Throughout the 1990s, there was an epidemic of multidrug resistant Salmonella Typhimurium DT104 in both animals and humans in Scotland. The use of antimicrobials in agriculture is often cited as a major source of antimicrobial resistance in pathogenic bacteria of humans, suggesting that DT104 in animals and humans should demonstrate similar prevalences of resistance determinants. Until very recently, only the application of molecular methods would allow such a comparison and our understanding has been hindered by the fact that surveillance data are primarily phenotypic in nature. Here, using large scale surveillance datasets and a novel Bayesian approach, we infer and compare the prevalence of Salmonella Genomic Island 1 (SGI1), SGI1 variants, and resistance determinants independent of SGI1 in animal and human DT104 isolates from such phenotypic data. We demonstrate differences in the prevalences of SGI1, SGI1-B, SGI1-C, absence of SGI1, and tetracycline resistance determinants independent of SGI1 between these human and animal populations, a finding that challenges established tenets that DT104 in domestic animals and humans are from the same well-mixed microbial population

    A cross‐faculty simulation model for authentic learning

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    This paper proposes a cross‐faculty simulation model for authentic learning that bridges the gap between short group‐based simulations within the classroom and longer individual placements in professional working contexts. Dissemination of the model is expected to widen the use of authentic learning approaches in higher education (HE). The model is based on a cross‐faculty project in which UK HE students acted as professional developers to produce prototype educational games for academic clients from other subject areas. Perceptions about the project were obtained from interviews with project participants. The stakeholders believed the cross‐faculty simulation to be a motivating learning experience, whilst identifying possible improvements. To evaluate whether the authenticity of the student–client relationship could be improved, the interview data were compared to four themes for authentic learning described by Rule in 2006. The data supported Rule’s themes, whilst highlighting the added value gained from meta‐awareness of the simulation as a learning opportunity

    Comparison of the COBE FIRAS and DIRBE Calibrations

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    We compare the independent FIRAS and DIRBE observations from the COBE in the wavelength range 100-300 microns. This cross calibration provides checks of both data sets. The results show that the data sets are consistent within the estimated gain and offset uncertainties of the two instruments. They show the possibility of improving the gain and offset determination of DIRBE at 140 and 240 microns.Comment: Accepted for publication in the Astrophysical Journal 11 pages, plus 3 figures in separate postscript files. Figure 3 has three part

    The impact of multifactorial factors on the Quality of Life of Behçet's patients over 10 years.

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    OBJECTIVE: This study analyses the 2020 survey and reviews the 2009, 2014 surveys to ascertain which Behçet's symptoms, personal and family status, patients' lifestyle, and work-related outcomes impacted on Health-Related Quality of Life (HRQoL). METHODS: Four hundred and fifty-nine Behçet's patients submitted an online survey/questionnaire. Patients provided information on socio-demographic characteristics, disease duration, historical and current symptoms, systemic and topical medication, health related lifestyle, work-related outcomes regarding employment status and claiming benefits and Quality of Life (QoL) measured by EQ-5D index. RESULTS: Four hundred and nineteen patients met the inclusion criteria, and 371 who had full data (Males: Females: Others = 84:285:2, mean-age = 41.1 ± 23.3:38 ± 13.2:40 ± 5). The main symptoms associated with patients seeking medical care were mouth ulcers 30% and genital ulcers 23%, joint 14%, and eye problems 9%. The EQ-5D index for 2009, 2014, 2020 was (mean ± SD); 0.47 ± 0.38, 0.42 ± 0.37, 0.34 ± 0.40, respectively, p < 0.05. 2020 patients had the worst values of the five domains compared to 2014 and 2009. Interestingly, mobility value was the same over the 10 years of monitoring patients. Behçet's syndrome (BS) symptoms that had significant negative impact on QoL were; 2009 (arthropathy, neurological problems, pathergy reaction, and stomach/bowel symptoms), 2014 (arthropathy, headache, neurological problems, pathergy reaction, and skin lesions), 2020 (arthropathy, neurological problems, and stomach/bowel symptoms). The 2014 and 2020 surveys reported the QoL is significantly better in patients on immunosuppressant, who did sport, continued in employment and not receiving benefits. CONCLUSION: Joints and neurological symptoms are the main symptoms which had negative impact on BS patients over the 10 years, sociodemographic (gender, age, marital, and education status), lifestyle (medication, cannabis, drinking wine, and regular exercise), employment status (employee and no career change), and accessing benefits (never claim benefit) had significant influence on patients' HRQoL

    Submillimeter wavelength survey of the galactic plane from l = -5 deg to l = +62 deg: Structure and energetics of the inner disk

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    Results from a large scale survey of the first quadrant of the Milky Way galactic plane at wavelengths of 150, 250, and 300 microns with a 10x10 arcmin beam are presented. The emission detected in the survey arises from compact sources, most of which are identified with known peaks of 5 GHz and/or CO emission, and from an underlying diffuse background with a typical angular width of approximately 0.9 deg (FWHM) which accounts for most of the emission. A total of 80 prominent discrete sources were identified and characterized, of which about half were not previously reported at far infrared wavelengths. The total infrared luminosity within the solar circle is approximately 1 to 2x10 to the 10th power L sub 0, and is probably emitted by dust that resides in molecular clouds
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