3,154 research outputs found
Winter Grazing in a Grass-Fed System: Effect of Stocking Density and Sequential Use of Autumn-Stockpiled Grassland on Performance of Yearling Steers
Winter grazing can help reduce the need for purchased feeds in livestock production systems, when finishing cattle on pasture. Our objective was to evaluate the influence of stocking density and grazing stockpiled forage on performance of yearling steers during winter. Three grasslands were winter grazed for two years: I, naturalized pastureland, and II and III, sown and managed for hay production during the growing season but grazed in winter. Two stocking densities were used: low 7.41 and high 12.35 steers ha−1. Herbage mass was estimated before and after each grazing event, and disappearance (consumption, weathering, and trampling) was the difference between both. Forage mass and residual differed by stocking density (SD), year (YR), and grazing interval (GI), and disappearance differed by YR and GI. Grass and dead constituents of botanical composition differed by YR and GI. No differences were found for legumes and forbs. CP differed by YR and GI, and NDF and ADF differed only by YR. Steer average daily gain was 0.15 kg d−1 in 2011 and 0.68 kg d−1 in 2012 and varied by YR and GI. Acceptable gains in 2012 may be a product of environmental conditions that influenced herbage mass and nutritive value during stockpile and animal behavior during winter
Assembly in G1 phase and long-term stability are unique intrinsic features of CENP-A nucleosomes
Centromeres are the site of kinetochore formation during mitosis. Centromere protein A (CENP-A), the centromere-specific histone H3 variant, is essential for the epigenetic maintenance of centromere position. Previously we showed that newly synthesized CENP-A is targeted to centromeres exclusively during early G1 phase and is subsequently maintained across mitotic divisions. Using SNAP-based fluorescent pulse labeling, we now demonstrate that cell cycle-restricted chromatin assembly at centromeres is unique to CENP-A nucleosomes and does not involve assembly of other H3 variants. Strikingly, stable retention is restricted to the CENP-A/H4 core of the nucleosome, which we find to outlast general chromatin across several cell divisions. We further show that cell cycle timing of CENP-A assembly is independent of centromeric DNA sequences and instead is mediated by the CENP-A targeting domain. Unexpectedly, this domain also induces stable transmission of centromeric nucleosomes, independent of the CENP-A deposition factor HJURP. This demonstrates that intrinsic properties of the CENP-A protein direct its cell cycle-restricted assembly and induces quantitative mitotic transmission of the CENP-A/H4 nucleosome core, ensuring long-term stability and epigenetic maintenance of centromere position.FCT fellpwships: (SFRH/BD/74284/2010, SFRH/BPD/69115/2010), National Institutes of Health grant: (GM082989), Burroughs Wellcome Fund (Career Award in the Biomedical Sciences), Rita Allen Foundation
Scholar Award, Instituto Gulbenkian de Ciência, European Commission FP7 Program, EMBO
Dynamics of unvisited sites in presence of mutually repulsive random walkers
We have considered the persistence of unvisited sites of a lattice, i.e., the
probability that a site remains unvisited till time in presence of
mutually repulsive random walkers. The dynamics of this system has direct
correspondence to that of the domain walls in a certain system of Ising spins
where the number of domain walls become fixed following a zero termperature
quench. Here we get the result that
where is close to 0.5 and a function of the density of the
walkers . The number of persistent sites in presence of independent
walkers of density is known to be . We show that a mapping of the
interacting walkers' problem to the independent walkers' problem is possible
with provided are small. We
also discuss some other intricate results obtained in the interacting walkers'
case.Comment: 6 pages, 7 figure
Características químicas de um latossolo influenciadas por diferentes tipos e doses de cinzas.
O objetivo deste trabalho foi determinar o efeito do tipo e doses de cinza sobre características químicas do solo
Taxa de decomposição de adubos verdes e disponibilidade de N influenciando o feijoeiro comum em sistema agroecológico de produção.
Os objetivos deste trabalho foram avaliar a produção de fitomassa, a quantidade de N fornecida por ela e a taxa de decomposição de adubos verdes e seus efeitos na cultura do feijoeiro comum em sistema de produção agroecológica.bitstream/CNPAF-2010/29763/1/comt-175.pd
Transplant of Tissue-Engineered Artificial Autologous Human Skin in Andalusia: An Example of Coordination and Institutional Collaboration
A new model of tissue-engineered artificial autologous human skin developed in Andalusia is currently being transplanted into patients suffering from large burns within the Andalusian Public Healthcare System. This product is considered an advanced therapy medicinal product (ATMP) in Europe, and its clinical use implies meeting transplant and medicinal product legal requirements, being the Guidelines of Good Manufacturing Practice for ATMPs of particular importance. The preclinical research and clinical translation of the product have represented a technical, regulatory, and organizational challenge, which has taken 10 years since the first preclinical experiments were designed. Twelve patients with large burns, including 3 pediatric patients, have hitherto received artificial autologous skin grafts with an overall survival rate of 75% and positive clinical, homeostatic, and histologic results. Achieving such a milestone within our Healthcare System was possible through a multidisciplinary approach and the joint efforts of multiple publicly funded institutions and units under the coordination of the Andalusian Initiative for Advanced Therapies. In this article, we present the organizational model set up to facilitate collaboration and logistics among the professionals involved, totaling more than 80 people. The similarities between the tissue-engineered artificial autologous human skin transplant and other organ and tissue transplants, in terms of logistic requirements, reveal how regional and hospital transplant coordination have played a crucial role
Padrão de emergência de adultos do bicudo do algodoeiro, Anthonomus grandis, ao longo da safra e entressafra na região Centro-Oeste.
bitstream/item/111269/1/bpd332-2011.pd
Swelling-collapse transition of self-attracting walks
We study the structural properties of self-attracting walks in d dimensions
using scaling arguments and Monte Carlo simulations. We find evidence for a
transition analogous to the \Theta transition of polymers. Above a critical
attractive interaction u_c, the walk collapses and the exponents \nu and k,
characterising the scaling with time t of the mean square end-to-end distance
~ t^{2 \nu} and the average number of visited sites ~ t^k, are
universal and given by \nu=1/(d+1) and k=d/(d+1). Below u_c, the walk swells
and the exponents are as with no interaction, i.e. \nu=1/2 for all d, k=1/2 for
d=1 and k=1 for d >= 2. At u_c, the exponents are found to be in a different
universality class.Comment: 6 pages, 5 postscript figure
Effect of green manure species and their sowing dates on common bean crop.
Nitrogen is the most required nutrient by common bean (Phaseolus vulgaris L.). Although common bean can obtain this nutrient from atmosphere by the biological nitrogen fixation (BNF) process, the fixed amounts are not enough to supply all plant necessities. Under agroecological production systems, part of the required N could be supplied by green manures as an alternative to fertilizers
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