172 research outputs found

    Synchronization techniques to increase the utilization of artificial insemination in beef and dairy cattle

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    Abstract The main objective of the implementation of Artificial Insemination (AI) in cattle is to produce a sustained genetic progress in the herd. Although AI is an old reproductive biotechnology, its widespread implementation is very recent and is mainly due to the use of protocols that allows the AI without heat detection, commonly called fixed-time artificial insemination (FTAI). The development of FTAI protocols also allowed the application of AI in larger, extensively managed, herds and especially in suckled cows instead of just reducing the breeding programs to the heifers. FTAI treatments are widely used in South America, with about 2,500,000 cows inseminated in the last season in Argentina and about 6,500,000 in Brazil. This manuscript aims to present and describe several treatments available and some of the factors that may affect pregnancy rates

    Asociación entre las características morfológicas y la producción de leche en vacas Holstein

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    El objetivo de este estudio fue identificar las características morfológicas de tipo que contribuyen a explicar la variación de la producción en vacas Holstein. Se calificaron morfométricamente 1.290 vacas de la raza Holstein de cuatro tambos comerciales de la Provincia de Buenos Aires (Argentina). Los 15 caracteres morfológicos calificados fueron: inserción anterior de ubre (FU); altura de ubre posterior (RUH); ancho ubre posterior (RUW); ligamento suspensorio medio (UC); profundidad de la ubre (UD); colocación de pezones posterior (TP); longitud de los pezones (TL); estatura (ST); angulosidad (ANG); fortaleza (SG); ancho de grupa (RW); ángulo de grupa (RA); patas posteriores, vista posterior (RLRV); patas posteriores, vista lateral (RLS) y ángulo de pezuña (FA). El sistema de clasificación utilizado fue el propuesto por ACHA. Se aplicó el algoritmo de partición correspondiente a un árbol de clasificación sobre las dos categorías de producción de leche extremas (alta y baja producción) previamente definidas según los percentiles 33 y 66 de la variable 305 días equivalente maduro (305EM). Esta técnica multivariada constituye una alternativa a los modelos clásicos de regresión ya que sus resultados no se ven afectados por correlaciones entre las variables explicativas. Los resultados sugieren que valoraciones altas del ancho de ubre combinado con valoraciones altas de la fortaleza, son las métricas de tipo que más contribuyen a explicar mayores promedios de producción de leche en esta raz

    The effect of Zr and Sn additions on the microstructure of Ti-Nb-Fe gum metals with high elastic admissible strain

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    An open challenge on structural biomaterials is to obtain low-cost Ti-alloys with high elastic admissible strength (the ratio of yield strength to modulus). To reach this goal, we designed and characterized three quaternary alloys from the Ti-Nb-Fe system with additions of Zr and Sn. The samples were solution-treated and tested under two conditions: water-quenched and aged at 450 °C. Microstructures were analyzed with aid of scanning and transmission electron microscopy. Tensile tests performed at room-temperature confirmed a remarkable yield strength of 1271 MPa with an elastic modulus close to 90 GPa among aged Ti-19Nb-2.5Fe-6Sn (wt%) samples. Solution-treated Ti-19Nb-2.5Fe-10Zr samples presented a good combination of yield-strength and elastic modulus (1027 MPa and 69 GPa, respectively), displaying an elastic admissible strength close to 1.5. Although Zr and Sn are equally distributed between matrix and precipitates, the diffusion of Nb and Fe seem to be inhibited by the presence of Sn. As a result, Sn allows higher yield-strengths and more refined secondary α-phase, while Zr has a stronger effect on reducing the elastic modulus. In the end, a materials selection chart is presented to help designers to select materials for orthopedic implants considering the elastic admissible strain and cost as major guidelines16011861195CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPNão tem2014/24449-0; 2016/22714-3; 2016/24693-3Funding: This work was supported by FAPESP (São Paulo State Research Foundation, grants numbers 2014/24449-0, 2016/22714-3 and 2016/24693-3) and CNPq (National Council for Scientific and Technological Development). The authors gratefully acknowledge Prof. Hamish Fraser for the use of experimental facilities at the Center for Electron Microscopy and Analysis (CEMAS), at the Ohio State University, USA, and thank CBMM Co. for the Nb supply. The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study. Data will be made available upon reques

    Long-term supplementation with anthocyanin-rich or -poor Rubus idaeus berries does not influence microvascular architecture nor cognitive outcome in the APP/PS-1 mouse model of Alzheimer’s disease

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    Disruption of microvascular architecture is a common pathogenic mechanism in the progression of Alzheimer’s disease (AD). Given the anti-angiogenic activity of berry (poly)phenols, we investigated whether long-term feeding of Rubus idaeus (raspberries) could ameliorate cerebral microvascular pathology and improve cognition in the APP/PS-1 mouse model of AD. Male C57Bl/6J mice (50 wild type, 50 APP/PS-1) aged 4-months were fed for 24-weeks, with a normal diet enriched with either 100 mg/day glucose (control diet) or supplemented with glucose and freeze-dried anthocyanin-rich (red) or -poor (yellow) raspberries (100 mg/day) and assessed/sampled post intervention. Cerebral microvascular architecture of wild-type mice was characterised by regularly spaced capillaries with uniform diameters, unlike APP/PS-1 transgenic mice which showed dysregulated microvascular architecture. Long-term feeding of raspberries demonstrated limited modulation of microbiota and no substantive effect on microvascular architecture or cognition in either mice model although changes were evident in endogenous cerebral and plasmatic metabolites

    Social Experiments in the Mesoscale: Humans Playing a Spatial Prisoner's Dilemma

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    Background: The evolutionary origin of cooperation among unrelated individuals remains a key unsolved issue across several disciplines. Prominent among the several mechanisms proposed to explain how cooperation can emerge is the existence of a population structure that determines the interactions among individuals. Many models have explored analytically and by simulation the effects of such a structure, particularly in the framework of the Prisoner’s Dilemma, but the results of these models largely depend on details such as the type of spatial structure or the evolutionary dynamics. Therefore, experimental work suitably designed to address this question is needed to probe these issues. Methods and Findings: We have designed an experiment to test the emergence of cooperation when humans play Prisoner’s Dilemma on a network whose size is comparable to that of simulations. We find that the cooperation level declines to an asymptotic state with low but nonzero cooperation. Regarding players ’ behavior, we observe that the population is heterogeneous, consisting of a high percentage of defectors, a smaller one of cooperators, and a large group that shares features of the conditional cooperators of public goods games. We propose an agent-based model based on the coexistence of these different strategies that is in good agreement with all the experimental observations. Conclusions: In our large experimental setup, cooperation was not promoted by the existence of a lattice beyond a residual level (around 20%) typical of public goods experiments. Our findings also indicate that both heterogeneity and a ‘‘moody’

    Changes in vegetation composition and structure following livestock exclusion in a temperate fluvial wetland

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    Questions: Responses of wetland systems to grazing can be highly variable with both positive or negative responses. However, the sustainable use of wetlands for grazing will depend on the management implemented and the resilience of each type of them. In this context, we addressed the question: will the vegetation in the studied wetland be able to recover its structural and functional parameters in the short term after livestock exclusion?. Location: Temperate fluvial wetlands in the middle Delta of the Paraná River, Argentina, South America. Methods: We evaluated the effect of cattle ranching on vegetation composition and diversity by determining changes in species richness and evenness, biomass (green and dry vegetative, and reproductive biomass), and litter content. We also analyzed the changes in biomass of weeds and of species according to their forage quality, toxicity, and growth form. We applied a randomized block design (by topographic position) with repeated measures over time, using livestock exclusion as treatment. Results: After 16 months, livestock exclusion affected vegetation species richness, but did not have a significant effect on diversity due to a slightly compensatory effect of evenness. Species composition differed markedly among treatments over time. There was an increase in dry and green vegetative biomass and litter content after eight months of exclusion, while changes in reproductive biomass occurred later. The increase in these variables was closely related to changes in biomass of species with erect habit and good forage quality. Conclusions: Livestock exclusion increased the forage value for the studied wetland by the development of natural palatable species typical of these environments. This shift in species composition promoted a higher production in biomass in the ungrazed areas. This suggests a remarkable recovery of the structural and functional parameters of the vegetation communities in the short term (two years).Fil: Magnano, Andrea Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Krug, Cecilia Pamela. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; ArgentinaFil: Casa, Valeria. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; ArgentinaFil: Quintana, Ruben Dario. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; Argentin

    ICTV Virus Taxonomy Profile: Ophioviridae

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    [EN] The Ophioviridae is a family of filamentous plant viruses, with single-stranded negative, and possibly ambisense, RNA genomes of 11.3-12.5 kb divided into 3-4 segments, each encapsidated separately. Virions are naked filamentous nucleocapsids, forming kinked circles of at least two different contour lengths. The sole genus, Ophiovirus, includes seven species. Four ophioviruses are soil-transmitted and their natural hosts include trees, shrubs, vegetables and bulbous or corm-forming ornamentals, both monocots and dicots. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Ophioviridae, which is available at http://www.ictv.global/report/ophioviridae.Production of this summary, the online chapter and associated resources was funded by a grant from the Wellcome Trust (WT108418AIA).Garcia, M.; Dal Bo, E.; Da Graca, JV.; Gago Zachert, SP.; Hammond, J.; Moreno, P.; Natsuaki, T.... (2017). ICTV Virus Taxonomy Profile: Ophioviridae. Journal of General Virology. 98(6):1161-1162. doi:10.1099/jgv.0.000836S1161116298

    How a firm can induce legislators to adopt a bad policy

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    This paper shows why a majority of legislators may vote for a policy that benefits a firm but harms all legislators. The firm may induce legislators to support the policy by suggesting that it is more likely to invest in a district where voters or their representative support the policy. In equilibrium, no one vote may be decisive, so each legislator who seeks the firm’s investment votes for the policy, though all legislators would be better off if they all voted against the policy. And when votes reveal information about the district, the firm’s implicit promise or threat can be credible. Unlike influence mechanisms based on contributions or bribes, the behavior considered is time consistent and in line with the low campaign contributions by special interests
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