8,864 research outputs found

    Computer simulations of cosmic-ray diffusion near supernova remnant shock waves

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    A plasma simulation model was used to study the resonant interactions between streaming cosmic-ray ions and a self-consistent spectrum of Alfven waves, such as might exist in the interstellar medium upstream of a supernova remnant shock wave. The computational model is a hybrid one, in which the background interstellar medium is an MHD fluid and the cosmic-rays are discrete kinetic particles. The particle sources for the electromagnetic fields are obtained by averaging over the fast cyclotron motions. When the perturbed magnetic field is larger than 10 percent of the background field, the macro- and microphysics are no longer correctly predicted by quasi-linear theory. The particles are trapped by the waves and show sharp jumps in their pitch-angles relative to the background magnetic field, and the effective ninety-degree scattering time for diffusion parallel to the background magnetic field is reduced to between 5 and 30 cyclotron periods. Simulation results suggest that Type 1 supernova remnants may be the principal sites of cosmic ray acceleration

    A Comparative Study of the Magnitude, Frequency and Distribution of Intense Rainfall in the United Kingdom

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    During the 1960s, a study was made of the magnitude, frequency and distribution of intense rainfall over the UK, employing data from more than 120 daily-read rain gauges covering the period 1911 to 1960. Using the same methodology, that study was recently updated utilizing data for the period 1961 to 2006 for the same gauges, or from those nearby. This paper describes the techniques applied to ensure consistency of data and statistical modelling. It presents a comparison of patterns of extreme rainfalls for the two periods and discusses the changes that have taken place. Most noticeably, increases up to 20% have occurred in the north west of the country and in parts of East Anglia. There have also been changes in other areas, including decreases of the same magnitude over central England. The implications of these changes are considered

    Rapid communication: Physical and linkage mapping of the porcine calcitonin (CALC) gene

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    Genus and Species. Sus scrofa. Locus. Porcine calcitonin (CALC) gene. Source and Description of Primers. Primers, CCA1F and CCA1R, were designed from canine calcitonin sequence (GenBank Accession no. AJ271090) to amplify genomic porcine DNA. Using sequence obtained from the amplified PCR product, additional pig-specific primers (CIPBF, CIPBR, CIPCF, CIPCR) were designed

    Evidence for Solar Metallicities in Massive Star-forming Galaxies at z>~2

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    We present results of near-IR spectroscopic measurements of 7 star-forming galaxies at 2.1<z<2.5. Drawn from a large spectroscopic survey of galaxies photometrically pre-selected by their U_nGR colors to lie at z~2, these galaxies were chosen for their bright rest-frame optical luminosities (K_s<=20.0). Most strikingly, the majority of the sample of 7 galaxies exhibit [NII]/Ha nebular emission line ratios indicative of at least solar HII region metallicities, at a lookback time of 10.5 Gyr. The broadband colors of the K_s-bright sample indicate that most have been forming stars for more than a Gyr at z~2, and have already formed stellar masses in excess of 10^11 Msun. The descendants of these galaxies in the local universe are most likely metal-rich and massive spiral and elliptical galaxies, while plausible progenitors for them can be found among the population of z~3 Lyman Break Galaxies. While the K_s-bright z~2 galaxies appear to be highly evolved systems, their large Ha luminosities and uncorrected Ha star-formation rates of 24-60 Msun/yr indicate that active star formation is still ongoing. The luminous UV-selected objects presented here comprise more than half of the high-redshift (z>1.5) tails of current K-band-selected samples such as the K20 and Gemini Deep Deep surveys.Comment: 15 pages including 5 figures. Accepted for publication in Ap

    Spatially Resolved Stellar Populations of Eight GOODS-South Active Galactic Nuclei at z ~ 1

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    We present a pilot study of the stellar populations of eight active galactic nucleus (AGN) hosts at z ~ 1 and compare with (1) lower redshift samples and (2) a sample of nonactive galaxies of similar redshift. We utilize K' images in the Great Observatories Origins Deep Survey South field obtained with the laser guide star adaptive optics system at Keck Observatory. We combine these K' data with B, V, i, and z imaging from the Advanced Camera for Surveys on Hubble Space Telescope to give multicolor photometry at a matched spatial resolution better than 100 mas in all bands. The hosts harbor AGNs as inferred from their high X-ray luminosities (LX > 10^42 erg s^–1) or mid-IR colors. We find a correlation between the presence of younger stellar populations and the strength of the AGN, as measured with [O III] line luminosity or X-ray (2-10 keV) luminosity. This finding is consistent with similar studies at lower redshift. Of the three Type II galaxies, two are disk galaxies and one is of irregular type, while in the Type I sample there are only one disk-like source and four sources with smooth, elliptical/spheroidal morphologies. In addition, the mid-IR spectral energy distributions of the strong Type II AGNs indicate that they are excited to Luminous InfraRed Galaxy (LIRG) status via galactic starbursting, while the strong Type I AGNs are excited to LIRG status via hot dust surrounding the central AGN. This supports the notion that the obscured nature of Type II AGNs at z ~ 1 is connected with global starbursting and that they may be extincted by kpc-scale dusty features that are by-products of this starbursting

    Differential contractile response of critically ill patients to neuromuscular electrical stimulation

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    BACKGROUND: Neuromuscular electrical stimulation (NMES) has been investigated as a preventative measure for intensive care unit-acquired weakness. Trial results remain contradictory and therefore inconclusive. As it has been shown that NMES does not necessarily lead to a contractile response, our aim was to characterise the response of critically ill patients to NMES and investigate potential outcome benefits of an adequate contractile response. METHODS: This is a sub-analysis of a randomised controlled trial investigating early muscle activating measures together with protocol-based physiotherapy in patients with a SOFA score ≥ 9 within the first 72 h after admission. Included patients received protocol-based physiotherapy twice daily for 20 min and NMES once daily for 20 min, bilaterally on eight muscle groups. Electrical current was increased up to 70 mA or until a contraction was detected visually or on palpation. Muscle strength was measured by a blinded assessor at the first adequate awakening and ICU discharge. RESULTS: One thousand eight hundred twenty-four neuromuscular electrical stimulations in 21 patients starting on day 3.0 (2.0/6.0) after ICU admission were included in this sub-analysis. Contractile response decreased from 64.4% on day 1 to 25.0% on day 7 with a significantly lower response rate in the lower extremities and proximal muscle groups. The electrical current required to elicit a contraction did not change over time (day 1, 50.2 [31.3/58.8] mA; day 7, 45.3 [38.0/57.5] mA). The electrical current necessary for a contractile response was higher in the lower extremities. At the first awakening, patients presented with significant weakness (3.2 [2.5/3.8] MRC score). When dividing the cohort into responders and non-responders (> 50% vs. ≤ 50% contractile response), we observed a significantly higher SOFA score in non-responders. The electrical current necessary for a muscle contraction in responders was significantly lower (38.0 [32.8/42.9] vs. 54.7 [51.3/56.0] mA, p < 0.001). Muscle strength showed higher values in the upper extremities of responders at ICU discharge (4.4 [4.1/4.6] vs. 3.3 [2.8/3.8] MRC score, p = 0.036). CONCLUSION: Patients show a differential contractile response to NMES, which appears to be dependent on the severity of illness and also relevant for potential outcome benefits. TRIAL REGISTRATION: ISRCTN ISRCTN19392591 , registered 17 February 201

    Prediction Equations for Estimating Lean Quantity in 15- to 50-kg Pigs

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    Equations for predicting the quantity of lean in the young pig were developed from measurements on 48 pigs (16.8 to 48.5 kg body weight) representing four crossbred mating types; maternal breed(s) × maternal breed(s), paternal breed(s) × maternal breed(s), paternal breed(s) × paternal breed(s) and porcine stress-susceptible × mixed breed. Within litter and sex, each of three pigs was assigned randomly to a light, intermediate or heavy slaughter weight group such that each mating type was represented by six barrows and six gilts from four different litters. Thirteen measurements were obtained for each pig; body weight, body length, body circumference, front leg circumference, front leg length, shoulder depth, shoulder width, ham width, head width, shoulder fat, last rib fat, last lumbar fat and loin muscle depth. Fat measurements and loin depth were taken ultrasonically. Pigs were slaughtered, chilled and manually separated into lean and fat, bone, skin and feet and tail components. Fat composition was determined by the Goldfisch method and also an x-ray absorption procedure. Pigs averaged 32.0 kg body weight and 12.5 kg of lean. Prediction equations were developed by maximum R2 and stepwise regression procedures. The model that includes the 13 measured variables and average backfat produced a .97 R2 when predicting kilograms of lean (LWTA). Body weight was the only significant variable. The one-variable model of body weight (P\u3c.01) produced a .95 R2 Kilograms of lean was estimated for an additional 24 pigs using the one-variable model of body weight and the two-variable model of body weight and shoulder width. The variable LWTA was found to be highly correlated with both estimates of LWTA (r = .97). Results suggest that LWTA can be predicted using a simple model that could be adapted to applied situations
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