248 research outputs found

    The Effect of Various Levels of Dietary Sunflower Seeds on Performance and Carcass Characteristics of Growing-Finishing Pigs

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    Sunflower seeds have become an important crop in several midwestern states. In the past, sunflower seeds have been used primarily in the production of sunflower oil and sunflower meal, with some seeds being used in the production of confectionery seeds. Not all sunflower seeds are suitable for these uses. An alternate use of these seeds would be incorporating them into livestock diets. Sunflower seeds may contain 40% or more oil that is highly unsaturated in nature. In swine diets the addition of a fat source such as sunflower seeds would be primarily at the expense of a carbohydrate source in the diet. This would have the effect of increasing the energy content per kilogram of feed and of shifting the source of energy from carbohydrates to a mixture of carbohydrates and fat. The addition of sunflower seeds to swine diets is a relatively new concept. Substantial work has been done in the area of increasing the fat content of swine diets either by adding fat directly or by including high fat-type seeds such as soybeans. Although there is some variation in results, most studies indicate that adding fat to a swine diet will increase the feed efficiency of the pig and usually decrease feed consumption. There is much less agreement on the effect adding a fat source to a diet has on average daily gain. When adding a fat source to swine diets, one must also be concerned with the effects of the added fat on carcass composition and quality. Fat sources that are highly unsaturated can produce carcasses that are soft and less desirable to the meat packer. This results from a lower melting point of fat containing an increased level of unsaturated fatty acids. Pork storage also becomes a. concern because intramuscular fat that has a higher level of unsaturated fatty acids is more susceptible to oxidative rancidity, thereby producing a product that is less desirable to the consumer. All the effects described above can be moderated by the total fat content and the fatty ac id composition of the dietary fat. Therefore, various fat sources in different quantities could produce slightly different carcass characteristics in the pig. The objectives of these experiments were to determine the effects of feeding diets containing various levels of sunflower seeds to growing-finishing swine on: 1. Average daily gain, feed efficiency, and average daily feed intake. 2. Quantitative carcass characteristics such as carcass length, average backfat, tenth rib fat, loin eye area and kilograms of muscle contained in the carcass. 3. Qualitative carcass characteristics, including carcass firmness and color, firmness and marbling of the longissimus muscle. 4. Fatty acid composition of backfat. 5. Consumer acceptability of the meat product

    Global Properties of Locally Spatially Homogeneous Cosmological Models with Matter

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    The existence and nature of singularities in locally spatially homogeneous solutions of the Einstein equations coupled to various phenomenological matter models is investigated. It is shown that, under certain reasonable assumptions on the matter, there are no singularities in an expanding phase of the evolution and that unless the spacetime is empty a contracting phase always ends in a singularity where at least one scalar invariant of the curvature diverges uniformly. The class of matter models treated includes perfect fluids, mixtures of non-interacting perfect fluids and collisionless matter.Comment: 18 pages, MPA-AR-94-

    Global dynamics of the mixmaster model

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    The asymptotic behaviour of vacuum Bianchi models of class A near the initial singularity is studied, in an effort to confirm the standard picture arising from heuristic and numerical approaches by mathematical proofs. It is shown that for solutions of types other than VIII and IX the singularity is velocity dominated and that the Kretschmann scalar is unbounded there, except in the explicitly known cases where the spacetime can be smoothly extended through a Cauchy horizon. For types VIII and IX it is shown that there are at most two possibilities for the evolution. When the first possibility is realized, and if the spacetime is not one of the explicitly known solutions which can be smoothly extended through a Cauchy horizon, then there are infinitely many oscillations near the singularity and the Kretschmann scalar is unbounded there. The second possibility remains mysterious and it is left open whether it ever occurs. It is also shown that any finite sequence of distinct points generated by iterating the Belinskii-Khalatnikov-Lifschitz mapping can be realized approximately by a solution of the vacuum Einstein equations of Bianchi type IX.Comment: 16 page

    Crushing singularities in spacetimes with spherical, plane and hyperbolic symmetry

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    It is shown that the initial singularities in spatially compact spacetimes with spherical, plane or hyperbolic symmetry admitting a compact constant mean curvature hypersurface are crushing singularities when the matter content of spacetime is described by the Vlasov equation (collisionless matter) or the wave equation (massless scalar field). In the spherically symmetric case it is further shown that if the spacetime admits a maximal slice then there are crushing singularities both in the past and in the future. The essential properties of the matter models chosen are that their energy-momentum tensors satisfy certain inequalities and that they do not develop singularities in a given regular background spacetime.Comment: 19 page

    Assessing precipitation, evapotranspiration, and NDVI as controls of U.S. Great Plains plant production

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    Productivity throughout the North American Great Plains grasslands is generally considered to be water limited, with the strength of this limitation increasing as precipitation decreases. We hypothesize that cumulative actual evapotranspiration water loss (AET) from April to July is the precipitation-related variable most correlated to aboveground net primary production (ANPP) in the U.S. Great Plains (GP). We tested this by evaluating the relationship of ANPP to AET, precipitation, and plant transpiration (Tr). We used multi-year ANPP data from five sites ranging from semiarid grasslands in Colorado and Wyoming to mesic grasslands in Nebraska and Kansas, mean annual NRCS ANPP, and satellite-derived normalized difference vegetation index (NDVI) data. Results from the five sites showed that cumulative April-to-July AET, precipitation, and Tr were well correlated (R2: 0.54–0.70) to annual changes in ANPP for all but the wettest site. AET and Tr were better correlated to annual changes in ANPP compared to precipitation for the drier sites, and precipitation in August and September had little impact on productivity in drier sites. April-to-July cumulative precipitation was best correlated (R2 = 0.63) with interannual variability in ANPP in the most mesic site, while AET and Tr were poorly correlated with ANPP at this site. Cumulative growing season (May-to-September) NDVI (iNDVI) was strongly correlated with annual ANPP at the five sites (R2 = 0.90). Using iNDVI as a surrogate for ANPP, we found that county-level cumulative April–July AET was more strongly correlated to ANPP than precipitation for more than 80% of the GP counties, with precipitation tending to perform better in the eastern more mesic portion of the GP. Including the ratio of AET to potential evapotranspiration (PET) improved the correlation of AET to both iNDVI and mean county-level NRCS ANPP. Accounting for how different precipitation-related variables control ANPP (AET in drier portion, precipitation in wetter portion) provides opportunity to develop spatially explicit forecasting of ANPP across the GP for enhancing decision-making by land managers and use of grassland ANPP for biofuels

    Connection between the Accretion Disk and Jet in the Radio Galaxy 3C 111

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    We present the results of extensive multi-frequency monitoring of the radio galaxy 3C 111 between 2004 and 2010 at X-ray (2.4--10 keV), optical (R band), and radio (14.5, 37, and 230 GHz) wave bands, as well as multi-epoch imaging with the Very Long Baseline Array (VLBA) at 43 GHz. Over the six years of observation, significant dips in the X-ray light curve are followed by ejections of bright superluminal knots in the VLBA images. This shows a clear connection between the radiative state near the black hole, where the X-rays are produced, and events in the jet. The X-ray continuum flux and Fe line intensity are strongly correlated, with a time lag shorter than 90 days and consistent with zero. This implies that the Fe line is generated within 90 light-days of the source of the X-ray continuum. The power spectral density function of X-ray variations contains a break, with steeper slope at shorter timescales. The break timescale of 13 (+12,-6) days is commensurate with scaling according to the mass of the central black hole based on observations of Seyfert galaxies and black hole X-ray binaries (BHXRBs). The data are consistent with the standard paradigm, in which the X-rays are predominantly produced by inverse Compton scattering of thermal optical/UV seed photons from the accretion disk by a distribution of hot electrons --- the corona --- situated near the disk. Most of the optical emission is generated in the accretion disk due to reprocessing of the X-ray emission. The relationships that we have uncovered between the accretion disk and the jet in 3C 111, as well as in the FR I radio galaxy 3C 120 in a previous paper, support the paradigm that active galactic nuclei and Galactic BHXRBs are fundamentally similar, with characteristic time and size scales proportional to the mass of the central black holeComment: Accepted for publication in ApJ. 18 pages, 17 figures, 11 tables (full machine readable data-tables online in ApJ website
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