1,349 research outputs found

    Super-alimentation of gilts during lactation

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    Sows attempt to meet the sudden and large metabolic demand of lactation by increasing their level of voluntary food intake. However, the voluntary food intake of most sows during lactation generally does not provide sufficient energy or protein to meet their requirements for maintenance and milk production. By providing multiparous sows with extra food during lactation (via a gastric cannula) they remained in an anabolic state, and both milk production and piglet growth were increased (Matzat et al., 1990). Do gilts respond in the same way as sows to extra food in lactation? Gilts are smaller than sows and would be expected to have a greater impetus for body growth because they have not reached their mature body size. If gilts are provided with extra food during lactation, they might partition more of it into body tissue and less into milk. Gilts, fitted with gastric cannulas, were used to test the hypothesis that they would respond differently from the sows of Matzat et al. (1990) to extra food in lactation

    Geology of Sheet SZ 19 (Hurn-Christchurch): part of 1:50 000 sheet 329 (Bournemouth)

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    The original geological survey of the area comprising sheet SZ 19 was made by H W Bristow and J Trimmer at the one-inch to one-mile scale (1:63 360) as parts of Old Sheets 15 and 16 published in 1856 and 1855 Series Geological respectively. The drift deposits were not represented on these maps. Clement Reid resurveyed the area on the six-inch to one-mile scale (1:10,560) in 1893, and his results were incorporated in New Series One-Inch Geological Sheet 329 (Bournemouth), published in 1895 in both Solid and Drift editions, and in the accompanying memoir (Reid, 1898). A second edition of this memoir was produced by H J 0 White, and was published in 1917. White re-examined much of the ground, but the published maps remained unaltered. In 1983 the Institute of Geological Sciences (now British Geological Survey) was commissioned by the Department of the Environment (contract PECD7/1/0103-149/82) to provide new 1:10,000 geological maps of the Poole-Bournemouth area. This contract comprises the survey of ten 1:10,000 sheets, and parts of four others, (Figure 1) over three years, to form a basis for the planning of urban and industrial development, and the safeguarding of mineral and water resources. During 1983, in the first phase of the contract, the four constituent quadrants of Sheet SZ 19 were mapped as follows, under the direction of R W Gallois, District Geologist: SZ 19 NW B J Williams; SZ 19 NE E C Freshney; SZ 19 SW E C Freshney; SZ 19 SE C R Bristow

    A randomized trial of brief web-based prevention of unhealthy alcohol use: Participant self-selection compared to a male young adult source population.

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    How much a randomized controlled trial (RCT) sample is representative of or differs from its source population is a challenging question, with major implications for generalizability of results. It is particularly crucial for freely-available web-based interventions tested in RCTs since they are designed to reach broad populations and could increase health disparities if they fail to reach the more vulnerable individuals. We assessed the representativeness of a sample of participants in a primary/secondary prevention web-based brief intervention RCT in relation to its source population. Then we compared those recruited to those not recruited in the RCT. There is a mandatory army recruitment process in Switzerland at age 19 for men. Between August 2010 and July 2011, 12,564 men (source population) attended two recruitment centers and were asked to answer a screening questionnaire on alcohol use. Among 11,819 (94.1%) who completed it, 7027 (59.5%) agreed to participate in a longitudinal cohort study with regular assessments. In 2012, these participants were invited to a web-based brief intervention RCT. Participation was not dependent on the presence or quantity of alcohol use. We assessed the representativeness of the RCT sample in relation to the source population and compared participants recruited/not recruited in the RCT with respect to education level and alcohol use. The RCT sample differed from the source population: individuals 20 and over were significantly less represented (34.3% vs 37.9%, p = 0.006), as were those with lower education level (58.6% vs 63.0%, p = 0.0009). The prevalence of any alcohol use was higher in the RCT population (92.3% vs 90.6%, p = 0.03) but unhealthy alcohol use was less represented (37.1% vs 43.2%, p < 0.0001). Differences on alcohol use measures and education were similarly found when those recruited in the RCT were compared to those who were not, including in a multivariable model, showing independent associations between less unhealthy alcohol use and higher education and recruitment in the RCT. RCT participants differed from other members of the source population, with those participating in the RCT having higher prevalence of any alcohol use but lower levels of consumption and lower prevalence of indicators of unhealthy alcohol use. Individuals with higher education were overrepresented in the RCT sample. Selection bias may exist at both ends of the drinking spectrum and individuals with some indicators of greater vulnerability were less likely to participate. Results of web-based studies may not adequately generalize to the general population.Trial registration: The trial was registered at current controlled trials: ISRCTN55991918

    Investigating African trace gas sources, vertical transport, and oxidation using IAGOS-CARIBIC measurements between Germany and South Africa between 2009 and 2011

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    Between March 2009 and March 2011 a commercial airliner equipped with a custom built measurement container (IAGOS-CARIBIC observatory) conducted 13 flights between South Africa and Germany at 10–12 km altitude, traversing the African continent north-south. In-situ measurements of trace gases (CO, CH4, H2O) and aerosol particles indicated that strong surface sources (like biomass burning) and rapid vertical transport combine to generate maximum concentrations in the latitudinal range between 10°N and 10°S coincident with the inter-tropical convergence zone (ITCZ). Pressurized air samples collected during these flights were subsequently analyzed for a suite of trace gases including C2-C8 non-methane hydrocarbons (NMHC) and halocarbons. These shorter-lived trace gases, originating from both natural and anthropogenic sources, also showed near equatorial maxima highlighting the effectiveness of convective transport in this region. Two source apportionment methods were used to investigate the specific sources of NMHC: positive matrix factorization (PMF), which is used for the first time for NMHC analysis in the upper troposphere (UT), and enhancement ratios to CO. Using the PMF method three characteristic airmass types were identified based on the different trace gas concentrations they obtained: biomass burning, fossil fuel emissions, and “background” air. The first two sources were defined with reference to previously reported surface source characterizations, while the term “background” was given to air masses in which the concentration ratios approached that of the lifetime ratios. Comparison of enhancement ratios between NMHC and CO for the subset of air samples that had experienced recent contact with the planetary boundary layer (PBL) to literature values showed that the burning of savanna and tropical forest is likely the main source of NMHC in the African upper troposphere (10–12 km). Photochemical aging patterns for the samples with PBL contact revealed that the air had different degradation histories depending on the hemisphere in which they were emitted. In the southern hemisphere (SH) air masses experienced more dilution by clean background air whereas in the northern hemisphere (NH) air masses are less diluted or mixed with background air still containing longer lived NMHC. Using NMHC photochemical clocks ozone production was seen in the BB outflow above Africa in the NH

    Molecular-orbital theory for the stopping power of atoms in the low velocity regime:the case of helium in alkali metals

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    A free-parameter linear-combination-of-atomic-orbitals approach is presented for analyzing the stopping power of slow ions moving in a metal. The method is applied to the case of He moving in alkali metals. Mean stopping powers for He present a good agreement with local-density-approximation calculations. Our results show important variations in the stopping power of channeled atoms with respect to their mean values.Comment: LATEX, 3 PostScript Figures attached. Total size 0.54

    Competition between Fusion and Quasi-fission in the Formation of Super-heavy Elements

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    Quasifission is a non-equilibrium dynamical process resulting in rapid separation of the dinuclear system initially formed after capture and sticking of two colliding heavy nuclei. This can inhibit fusion by many orders of magnitude, thus suppressing the cross section for formation of superheavy elements. Measurements with projectiles from C to Ni, made at the Australian National University Heavy Ion Accelerator Facility, have mapped out quasifission characteristics and systematics using mass-angle distributions (MAD) - the fission mass-split as a function of centre-of-mass angle. These provide information on quasifission dynamics in the least model-dependent way. Quasifission time-scale information in the MAD has been compared with TDHF calculations of the collisions, with good agreement being found. Most significantly, the nuclear structure of the two colliding nuclei has a dramatic effect on quasifission probabilities and characteristics in gentle collisions at near-barrier energies. The effect of static deformation alignment, closed shells and N/Z matching can completely change reaction outcomes. The realization of this strong dependence makes modelling quasifission and superheavy element formation a challenging task, but should ultimately allow more reliable prediction of superheavy element formation cross sections
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