347 research outputs found

    Genetic parameters, heterosis, and breed effects for body condition score and mature cow weight in beef cattle

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    Understanding the genetic relationship between mature cow weight (MWT) and body condition score (BCS) is useful to implement selection programs focused on cow efficiency. The objectives of this study were to estimate genetic parameters, heterosis, and breed effects for MWT and BCS. In total, 25,035 and 24,522 overlapping records were available for MWT and BCS on 6,138 and 6,131 cows, respectively, from the Germplasm Evaluation program, a crossbred beef population at the U.S. Meat Animal Research Center. Pedigree was available for 48,013 individuals. Univariate animal models were used to estimate heritabilities for each trait by parity. Bivariate animal models were used to estimate genetic correlations between parities within a trait and between traits within parities. Bivariate repeatability animal models were used to estimate genetic correlations between traits across parities. Estimates of heritability for different parities ranged from 0.43 ± 0.05 to 0.55 ± 0.07 for MWT and from 0.12 ± 0.03 to 0.25 ± 0.04 for BCS and were lower with the repeatability model at 0.40 ± 0.02 and 0.11 ± 0.01 for MWT and BCS, respectively. Estimates of repeatability were high for MWT (0.67 ± 0.005) and low for BCS (0.22 ± 0.006). Estimates of genetic correlation for MWT and BCS between parities were, in general, high, especially between consecutive parities. Estimates of genetic correlation between MWT and BCS were positive and moderate, ranging from 0.32 ± 0.09 to 0.68 ± 0.14. The direct heterosis estimates were 21.56 ± 3.53 kg (P ≀ 0.001) for MWT and 0.095 ± 0.034 (P ≀ 0.001) for BCS. Ordered by decreasing MWT, the breeds ranked Brahman, Charolais, Angus, Simmental, Salers, Hereford, Santa Gertrudis, Chiangus, Brangus, Red Angus, Shorthorn, Maine-Anjou, Gelbvieh, Beefmaster, Limousin, and Braunvieh. Ordered by decreasing BCS, the breeds ranked Brahman, Red Angus, Charolais, Angus, Hereford, Brangus, Beefmaster, Chiangus, Salers, Simmental, Maine-Anjou, Limousin, Santa Gertrudis, Shorthorn, Gelbvieh, and Braunvieh. Estimates of breed differences for MWT were also adjusted for BCS (AMWT), and in general, AMWT depicted smaller differences between breeds with some degree of re-ranking (r = 0.59). These results suggest that MWT and BCS are at least moderately genetically correlated and that they would respond favorably to selection. Estimates of breed differences and heterotic effects could be used to parameterize multibreed genetic evaluations for indicators of cow maintenance energy requirements

    Identification of backgrounds in the EDELWEISS-I dark matter search experiment

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    This paper presents our interpretation and understanding of the different backgrounds in the EDELWEISS-I data sets. We analyze in detail the several populations observed, which include gammas, alphas, neutrons, thermal sensor events and surface events, and try to combine all data sets to provide a coherent picture of the nature and localisation of the background sources. In light of this interpretation, we draw conclusions regarding the background suppression scheme for the EDELWEISS-II phase

    Measurement of the response of heat-and-ionization germanium detectors to nuclear recoils

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    The heat quenching factor Q' (the ratio of the heat signals produced by nuclear and electron recoils of equal energy) of the heat-and-ionization germanium bolometers used by the EDELWEISS collaboration has been measured. It is explained how this factor affects the energy scale and the effective quenching factor observed in calibrations with neutron sources. This effective quenching effect is found to be equal to Q/Q', where Q is the quenching factor of the ionization yield. To measure Q', a precise EDELWEISS measurement of Q/Q' is combined with values of Q obtained from a review of all available measurements of this quantity in tagged neutron beam experiments. The systematic uncertainties associated with this method to evaluate Q' are discussed in detail. For recoil energies between 20 and 100 keV, the resulting heat quenching factor is Q' = 0.91+-0.03+-0.04, where the two errors are the contributions from the Q and Q/Q' measurements, respectively. The present compilation of Q values and evaluation of Q' represent one of the most precise determinations of the absolute energy scale for any detector used in direct searches for dark matter.Comment: 28 pages, 7 figures. Submitted to Phys. Rev.

    Final results of the EDELWEISS-II WIMP search using a 4-kg array of cryogenic germanium detectors with interleaved electrodes

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    The EDELWEISS-II collaboration has completed a direct search for WIMP dark matter with an array of ten 400-g cryogenic germanium detectors in operation at the Laboratoire Souterrain de Modane. The combined use of thermal phonon sensors and charge collection electrodes with an interleaved geometry enables the efficient rejection of gamma-induced radioactivity as well as near-surface interactions. A total effective exposure of 384 kg.d has been achieved, mostly coming from fourteen months of continuous operation. Five nuclear recoil candidates are observed above 20 keV, while the estimated background is 3.0 events. The result is interpreted in terms of limits on the cross-section of spin-independent interactions of WIMPs and nucleons. A cross-section of 4.4x10^-8 pb is excluded at 90%CL for a WIMP mass of 85 GeV. New constraints are also set on models where the WIMP-nucleon scattering is inelastic.Comment: 23 pages, 5 figures; matches published versio

    Superimposed impacts of enhanced [CO2] and high temperature on the photosynthetic metabolism of C. arabica and C. canephora genotypes.

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    Summary: Coffee crop has been predicted to become threatened by future climate changes and global warming conditions. Yet, the long-term effects of elevated [CO2] on this plant remain to be fully elucidated. In this context, this work aims at linking coffee biochemical responses to environmental changes of [CO2] and temperature on genotypes from the two major producing species, using the photosynthetic metabolism as probe to evaluate the plant acclimation ability. Potted plants from C. arabica cv. IPR 108 and of C. canephora cv. Conilon Clone 153 were grown under environmental controlled conditions, either at 380 or 700 ?L CO2 L-1 air, for 1 year, without water, nutrient or root development restrictions. After that the temperature was gradually increased from 25/20 ÂșC (day/night) up to 42/34 ÂșC. The effects of elevated [CO2] and enhanced temperature on the photosynthetic structures were assessed through the characterization of the lipid components of chloroplast membranes, whereas the leaf metabolic performance was evaluated through the thylakoid electron transport rates (involving both photosystem (PS) I and II), and the activities of enzymes (ribulose 1,5-biphosphate carboxylase/oxygenase and ribulose 5-phosphate kinase), as well as through stable isotopes of C and N. The activities of respiratory enzymes (NADH-dependent malate dehydrogenase and pyruvate kinase) were also analyzed. The results pointed for a higher functional status along the experiment in the plants grown under elevated [CO2], with special relevance at 37 and 42ÂșC in IPR108. These results could be related to the qualitative changes of the membrane lipid matrix that might have helped to preserve suitable membrane fluidity for the membrane bound events (e.g., thylakoid electron transport). The PSs and enzyme data reflect an enhancement of the energetic metabolism (both photosynthesis and respiration), mostly, until 31 ÂșC for IPR108 and 37 ÂșC for CL153 at normal [CO2]. Yet, under enhanced [CO2] it was found an increase in the temperature (to 37 ÂșC) at which maximal values of some parameters in IPR108 (MDH, PSs activities, RuBisCO) were observed, concomitantly with the maintenance of high performance in other parameters when compared to the 380 plants. Under the highest temperature (42 ÂșC) the enzymes were the most sensitive point, displaying the strongest reductions, irrespective of genotype and [CO2] treatments. The temperature promoted changes in leaf ?13C, irrespective of genotype and [CO2], reflecting a decrease in WUE with heat. The changes in ?15N values may indicate different limitation steps of N assimilation, requiring further investigation. It was concluded that the coffee plants grown under elevated [CO2] apparently showed a better endurance to high temperatures, what is quite relevant in a context of predicted climate changes and global warming scenarios

    A search for low-mass WIMPs with EDELWEISS-II heat-and-ionization detectors

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    We report on a search for low-energy (E < 20 keV) WIMP-induced nuclear recoils using data collected in 2009 - 2010 by EDELWEISS from four germanium detectors equipped with thermal sensors and an electrode design (ID) which allows to efficiently reject several sources of background. The data indicate no evidence for an exponential distribution of low-energy nuclear recoils that could be attributed to WIMP elastic scattering after an exposure of 113 kg.d. For WIMPs of mass 10 GeV, the observation of one event in the WIMP search region results in a 90% CL limit of 1.0x10^-5 pb on the spin-independent WIMP-nucleon scattering cross-section, which constrains the parameter space associated with the findings reported by the CoGeNT, DAMA and CRESST experiments.Comment: PRD rapid communication accepte

    Thylakoid lipids changes may account for photosynthetic acclimation ability of two coffea species subjected to heat.

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    Summary: Coffee is one of the world?s most traded agricultural products, and its production could be threatened by global warming. The aim of this work was to evaluate the effects of heat on photosynthetic activity and thylakoid membrane lipid dynamics, on genotypes of the two major coffee producing species. Potted plants from C. arabica L. cv. IPR108 and C. canephora Pierre Ex A. Froehner cv. Conilon Clone 153 were grown for 1 year under controlled conditions of temperature (25/20ÂșC, day/night), irradiance (650-800 ?mol m-2 s-1), RH (75%), photoperiod (12 h), and 380 ?L CO2 L-1. Thereafter, temperature was gradually raised to 42/34ÂșC (0.5ÂșC/ day), with a 7 days stabilization step at 31, 37 and 42ÂșC. Studies focused modifications of thylakoid lipid composition and photosynthetic performance. In CL153 photosynthetic capacity (Amax) was not affected until 42ÂșC (40% reduction). In IPR108 it was reduced 35 and 57% at 37ÂșC at 42ÂșC, respectively. Thylakoid electron transport rate for photosystems (PS) I and II increased (ca. 10-25%) up to 37ÂșC in both genotypes. At 42ÂșC only IPR108 presented depressed activities on PSII (15%) and PSI (18%). Under 37 and 42ÂșC, CL153 plants presented digalactosyldiacylglycerol (DGDG) (ca. 42%) and monogalactosyldiacylglycerol (MGDG) (28-34%) increases, while IPR108 showed higher MGDG at all temperatures. In CL153 less unsaturated DGDG and phosphatidylglycerol (PG) along with stable or increased DGDG/MGDG ratio, may have contributed to sustain thylakoid electron flow at 37ÂșC and even 42ÂșC. IPR108 displayed a strong PG rise at all temperatures, in accordance with enhanced PSs activity

    A glimpse of climate change impact on C. Arabica L. and C. Canephora Pierre ex A. Froehner physiology: the combined effects of enhanced growth CO2 and temperature.

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    Summary: The effective impact of climate changes on the coffee plant physiology, promoted by enhanced air [CO2] and global warming remain to be fully elucidated through biological studies. Therefore, this work aims at linking important coffee physiological responses to environmental changes of enhanced growth [CO2] and temperature on genotypes from the two major producing species. Potted plants from C. arabica cv. IPR 108 and of C. canephora cv. Conilon Clone 153 were grown under environmental controlled conditions, either at 380 or 700 ?L CO2 L-1 air, for 1 year, without water, nutrient or root development restrictions. After that the temperature was gradually increased from 25/20 ÂșC (day/night) up to 42/34 ÂșC. The long-term impacts of enhanced growth [CO2] and enhanced temperature on the photosynthetic functioning were assessed at 25/20 ÂșC, 31/25 ÂșC, 37/30 ÂșC and 42/34 ÂșC, through leaf gas exchanges (rates of net photosynthesis, Pn, stomatal conductance, gs, transpiration, Tr, and photosynthetic capacity, Amax), instantaneous water use efficiency (iWUE), fluorescence parameters (photochemical efficiency of the photosystem II under dark, Fv/Fm, and light, Fv?/Fm?, conditions, as well as the photochemical, qP, and non-photochemical, NPQ, quenchings, and quantum yield of the linear electron transport, ?e), photosynthetic pigments (chlorophyll and carotenoids) and some molecules with antioxidant role (ascorbate and ?-tocopherol). The results showed that enhanced [CO2] stimulates photosynthetic functioning, without negative down-regulation. Minor impacts were found in the photochemical performance until 37 ÂșC, but extensive impacts were shown at 42 ÂșC, especially in IPR108. Remarkable was the finding that enhanced [CO2] preserved a higher functional status (Pn, Amax, Fo, Fv/Fm) at high temperatures (37 and 42 ÂșC), what seems quite relevant under the predicted climate changes and global warming scenarios