128 research outputs found
A new application of pelvis area data as culling tool to aid in the management of dystocia in heifers
Although fetomaternal disproportion is
the major cause of dystocia in heifers, pelvis area (PA)
is not recommended as a culling tool due to its relatively
low importance and genetic correlation with calf birth
weight (BWT), the most important factor associated
with dystocia. The objective of this observational study
of 484 limited bred yearling beef heifers was to compare
the effects of different methods of adjustment of PA data
for culling to select against dystocia. Multivariable analyses
were used to determine predictors of PA, calf BWT,
and dystocia. Hypothetical culling rates of 10 and 20%
were then applied after ranking heifers by each of the
following: unadjusted PA, PA adjusted to 365 d of age by
subtracting 0.27 cm2 per day of age difference between
each heifer’s age and 365 d (APA), PA:prebreeding
BW ratio (PA:BW), PA adjusted to the median BW of
the group using the regression coefficient of PA on BW
within age group (BWPA), and PA similarly adjusted to
the median lean BW (LBWPA). Dam parity, sire, prebreeding
age, prebreeding BW, and prebreeding BCS
were associated with PA whereas dam parity, sire, own BWT, PA, AI bull, and calf gender were associated with
calf BWT (P < 0.05). Dam parity, calf BWT, and either
BWPA or LBWPA were the only independent predictors
of dystocia (P < 0.05). Adjusting PA to BW or lean BW
(LBW) improved the sensitivity and specificity to predict
dystocia. After hypothetical culling by PA, retained
heifers were heavier and had a higher calving rate and
calves tended to be heavier at birth compared to culled
heifers, but dystocia rates were not different. Culling by
APA resulted in similar effects, except that dystocia rate
tended to be lower in retained heifers. Culling by PA:BW
resulted in lower dystocia rate in retained than in culled
heifers, but retained heifers had lower prebreeding BW
than culls. Culling by BWPA and LBWPA resulted in
lower proportions with dystocia and a tendency towards
higher calving rates in the retained heifers, without affecting
the prebreeding BW or calf BWT. It is concluded that
pelvimetry is a useful culling tool to aid in the management
of dystocia in yearling heifers and that adjustment
of PA to median BW or LBW within age group improves
its accuracy and avoids the undesirable side effects.http://www.animal-science.org/hb201
Nutrição mineral de hortaliças XXX: absorção de micronutrientes por quatro cultivares de morangueiro (Fragaria sp.)
The aim of this work was to estimate the differences in nutrients uptake and exportation of micronutrients by the fallowings cultivars: Campinas (IAC-2712), Camanducaia (IAC-3530); Monte Alegre (IAC-3113) and SH-2. The experimental was carried out in a soil - Terra Roxa Extruturada type, "Luiz de Queiroz", serie. The experimental design was that randomized blocks with four replications and analysed together following the design of split-plot. The soil of the plots were revolved to a deep of 12 cm. following application of 10 kg. organic matter/m². The fertilizers were applied in the groove and in the same amount for all cultivars: Ammonium sulfate (20% N); triple superpohsphate (20% P2O5); potassium chloride (60% K2O). Thirty days of ter planting, 10 g./plant of ammonium sulfate was applied. After 76 days from planting, the first sample was taken. Other samples were taken in equal intervals of 20 days, up to 216 days. The samples were devided into stems, leaves and fruits. Chemical analysis were sun for B, Cu, Fe, Mn and Zn. The followings conclusions could be drawn. The were differences our micronutrients content in stems and leaves among the cultivares (B, Cu, Fe, Zn) and in the fruits for B, Cu and Fe.Efetuou-se um estudo para avaliar a absorção e a extração de B, Cu, Fe, Mn e Zn nos cultivares Campinas (IAC-2712), Camanducaia (IAC-3530), Monte Alegre (IAC-3113), SH-2 em condições de Campo. O ensaio foi instalado em um solo pertencente ao grande grupo Terra Roxa Extruturada, na série "Luiz de Queiroz" em Piracicaba, SP. A adubação empregada foi uniforme para todos os cultivares e constou em 10 g/m linear de sulfato de amônio, superfosfato triplo e cloreto de ptoássio. Trinta dias após o transplante foram aplicados 10 g de sulfato de amônio por planta. As plantas foram amostradas aos 16 dias após o transplante e as demais amostragens feitas em intervalos regalares de vinte dias até aos 216 dias. As plantas foram divididas em caules (pecíolo + coroa), folhas e frutos e analisadas para B, Cu, Fe, Mn e Zn. O delineamento experimental foi de blocos inteiramente casualizados, com quatro repetições. Os cultivares diferem na absorção de Cu, Fe, Mm e Zn para caules, folhas e em B, Cu e Fe para os frutos. Os cultivares exportam em quantidades diferentes os micronutrientes, obedecendo a seguinte ordem decrescente: F, Zn, B, Mn e Cu
Gluons and the quark sea at high energies: distributions, polarization, tomography
This report is based on a ten-week program on "Gluons and the quark sea at
high-energies", which took place at the Institute for Nuclear Theory in Seattle
in Fall 2010. The principal aim of the program was to develop and sharpen the
science case for an Electron-Ion Collider (EIC), a facility that will be able
to collide electrons and positrons with polarized protons and with light to
heavy nuclei at high energies, offering unprecedented possibilities for
in-depth studies of quantum chromodynamics. This report is organized around
four major themes: i) the spin and flavor structure of the proton, ii)
three-dimensional structure of nucleons and nuclei in momentum and
configuration space, iii) QCD matter in nuclei, and iv) Electroweak physics and
the search for physics beyond the Standard Model. Beginning with an executive
summary, the report contains tables of key measurements, chapter overviews for
each of the major scientific themes, and detailed individual contributions on
various aspects of the scientific opportunities presented by an EIC.Comment: 547 pages, A report on the joint BNL/INT/Jlab program on the science
case for an Electron-Ion Collider, September 13 to November 19, 2010,
Institute for Nuclear Theory, Seattle; v2 with minor changes, matches printed
versio
Nutrição mineral de hortaliças: XXIX. absorção de macronutrientes por quatro cultivares de morangueiro (Fragaria spp.)
The aim of this work was to estimate the differences in growth (dry weight basis), nutrients uptake, fruits yield, total uptake and exportation of nutrients among several strawberry cultivars: Campinas (IAC-2712), Camanducaia (IAC-3530), Monte Alegre (IAC-3113) and SH-2. The experimental was carried out in the Escola Superior de Agricultura "Luiz de Queiroz", in field conditions, in 1975/76. The soil belongs to Terra Roxa Estruturada type, and "Luiz de Queiroz" serie. This soil has been cultivated for more than 25 years. The experimental design was that randomized blocks with four replications and analysed together following the design of split-plot. The soil of the plots were revolved to a deep of 12 cm following application of 10 kg organic matter/m². The fertilizers were applied in the groove and in the same amount for all cultivars: Ammonium sulfate (20% N), 10 g/m; triple superphosphate (20% P(2)0(5)) 10 g/m; Potassium cloride (60% K(2)0), 10 g/m. Therty days after planting, 10 g/plant of ammonium sulfate was applied. After 76 days from planting, the firsa sample was taken. Other samples were taken in equal intervals of 20 days, up to 216 days. When a decrease in fruitproduction was noted. The sample (plants) were divided in stems, leaves and fruits and chemical analysis were made for N, R, K, Ca, Mg e S. The variation on production (dry matter) nutrient uptake' and fruits yield, were obtained from data calculated by adjusted regression equation analysis. The maxima point from these equations were taken to show the total nutrient uptake. From the data obtained, the following conclusions could be drawn. Growth - The dry matter of stems, leaves and fruits were different among the cultivars. The production of dry matter by the stems and fruits were linnear for all cultivars up to 196 and 216 days. The highest productions on dry matter varied between 15 to 25 g and 12 to 20 g/plant. The maximum production of dry matter in the leaves among the cultivars varied between 20 to 30 g at 196 and 173 days respectivelly. The cultivars Campinas (IAC-2712) and Camanducaia (IAC-3530) produced more dry matter than SH-2 cultivar. Nutrient uptake -< The were differences on nutrient content in stems and leaves among cultivars (R, K, Ca, S, B) and in the fruits for N, R, K, Mg, S. The highest absorption of nutrients (days after planting) is shown in Table I. Yield - No significant difference in fruit production was observed among the cultivars. The highest yield among the cultivars showed a variation between 103 to 151 g per plant at the 207 and 207 days,Efetuou-se um estudo para avaliar a absorção e a extração dos macronutrientes nos seguintes cultivares de morangueiro: Campinas (IAC-2712); Camanducaia (IAC-3530) ; Monte Alegre (IAC-3113) e SH-2 em condições de campo. A instalação deu-se em um solo pertencente ao grande grupo Terra Roxa Estruturada, e à série "Luiz de Queiroz" cultivado intensivamente com hortaliças há mais de 25 anos, em Piracicaba-SP. A adubação aplicada foi uniforme para todos os cultivares. São apresentadas as concentrações dos macronutrientes em porcentagem nos seguintes órgãos: caules, folhas e frutos dos cultivares em função da idade (X) em dias. Constatou-se que os cultivares diferem quanto à absorção dos macronutrientes (R, K, Ca e S em relação a caules e folhas, e, N, R, K, Mg e S em relação aos frutos). Constatou-se também que os cultivares extraem totais diferentes de R, K, Ca, Mg e S sendo as extrações de R pelos cultivares menores do que as extrações de Ca e Mg, e no global as de Mg são equivalentes às de S. As quantidades máximas extraídas pelos cultivares para uma população de 150.000 plantas/ha foram : N - 192 kg; R - 24-50 kg; K - 133-244 kg; Ca - 76-116 kg; Mg - 30-34 kg; S - 13-27 kg. - A maior produção de matéria seca tanto nos órgãos como na planta inteira, ocorreu nos cultivares Campinas (IAC-2712) e Camanducaia (IAC-3530) e a menor produção verificou-se no cultivar SH-2. - Os cultivares diferem na absorção dos nutrientes: R, K, Ca, S para caules e folhas. E para frutos, N, R, K, Mg e S. - Os cultivares atingem o máximo da absorção de nutrientes nos órgãos nas seguintes épocas, em dias: - Os cultivares extraem e exportam totais diferentes de R, K, Ca e Mg. - Tanto os macronutrientes são extraídos em quantidades mais elevadas através das folhas e em menor proporção por caules e frutos. - As extrações de N, K e Ca são mais altas que aquelas dos demais macronutrientes. - As extrações de R pelos cultivares são menores que as de Ca e Mg, sendo ainda as extrações de Ca superiores às de Mg, enquanto no global as de Mg são equivalentes às de S. - A extração de macronutrientes verifica-se na ordem decrescente: K, N, Ca, Mg, S e P
Physical Processes in Star Formation
© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00693-8.Star formation is a complex multi-scale phenomenon that is of significant importance for astrophysics in general. Stars and star formation are key pillars in observational astronomy from local star forming regions in the Milky Way up to high-redshift galaxies. From a theoretical perspective, star formation and feedback processes (radiation, winds, and supernovae) play a pivotal role in advancing our understanding of the physical processes at work, both individually and of their interactions. In this review we will give an overview of the main processes that are important for the understanding of star formation. We start with an observationally motivated view on star formation from a global perspective and outline the general paradigm of the life-cycle of molecular clouds, in which star formation is the key process to close the cycle. After that we focus on the thermal and chemical aspects in star forming regions, discuss turbulence and magnetic fields as well as gravitational forces. Finally, we review the most important stellar feedback mechanisms.Peer reviewedFinal Accepted Versio
The Physics of Star Cluster Formation and Evolution
© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00689-4.Star clusters form in dense, hierarchically collapsing gas clouds. Bulk kinetic energy is transformed to turbulence with stars forming from cores fed by filaments. In the most compact regions, stellar feedback is least effective in removing the gas and stars may form very efficiently. These are also the regions where, in high-mass clusters, ejecta from some kind of high-mass stars are effectively captured during the formation phase of some of the low mass stars and effectively channeled into the latter to form multiple populations. Star formation epochs in star clusters are generally set by gas flows that determine the abundance of gas in the cluster. We argue that there is likely only one star formation epoch after which clusters remain essentially clear of gas by cluster winds. Collisional dynamics is important in this phase leading to core collapse, expansion and eventual dispersion of every cluster. We review recent developments in the field with a focus on theoretical work.Peer reviewe
Ciclos de carbono y nitrógeno en plantaciones de palma de aceite: claves para la productividad y la sostenibilidad / Carbon and nitrogen cycling in oil palm plantations: the keys to yield and sustainability
[Spanish] El alto rendimiento y la rentabilidad de las inversio nes en palma de aceite dependen de la fijación de carbono producto de la fotosíntesis en las ojas, la cual está limitada por la radiación, la temperatura y la disponibilidad de gua y nutrientes, en particular el nitrógeno. Los ciclos de carbono y nitrógeno también son factores determinantes para la condición del suelo en particular, la materia orgánica, la acidez y la actividad biológica), la salud de los ecosistemas acuáticos y las emisiones de gases de efecto invernadero. Aunque la productividad y los efectos am bientales del cultivo se han estudiado extensamente, es difícil predecir cómo podrían verse afectados por los cambios en el genotipo, en las condiciones ambientales o en las prácticas de manejo, dada la complejidad de las interacciones entre los ciclos de carbono y nitrógeno, y los factores antes mecanísticos, la integración de nuestro conocimiento a modelos mecanicistas predictivos es esencial para avanzar. Dicha integración se ha logrado recientemente para la palma de aceite utilizando el marco APSIM (www.apsim.info), el cual integra modelos de fisiología de cultivos y de ciclos de agua, carbono y nitrógeno. El modelo ha demostrado tener la capacidad de predecir el crecimiento vegetativo y el rendimiento aropiadamente, y de manera consistente en Papúa Nueva Guinea, en donde fue desarrollado. Ahora debe ser ensayado en un mayor rango de entornos. APSIM Oil Palm tiene un potencial considerable como herramienta para predecir el rendimiento y generar eficiencia al explorar escenarios cuya evaluación experimental no es plausible, tales como los efectos probables de una gestión de fertilizantes distinta, los efectos del tipo de clima y suelo en la productividad, la condición del suelo y el entorno.
[English] High yields and return on investment in oil palm all depend on the fixation of carbon by photosynthesis in the leaves, which is limited by radiation, temperature and the availability of water and nutrients, especially nitrogen. The carbon and nitrogen cycles are also key determinants of soil condition (particularly soil organic matter, acidity and biological activity), aquatic ecosystem health and greenhouse gas emissions. Although productivity and environmental effects of cultivation are well studied, it is difficult to predict how they might be affected by changes in genotype, environmental conditions or management practices, because of complex interactions between the carbon and nitrogen cycles and these factors. Integrating our knowledge into mechanistic predictive models is essential to move forward. Such integration has recently been achieved for oil palm using the APSIM framework (www.apsim.info), which integrates models of crop physiology and cycling of water, carbon and nitrogen. The model has been shown to predict vegetative growth and yield consistently well in Papua New Guinea, where it was developed. It now needs to be tested in a wider range of environments. APSIM Oil Palm has considerable potential as a tool for predicting yield and for efficiently exploring scenarios that are not feasible to assess experimentally, such as the likely effects of different fertilizer management, climate or soil type on productivity, soil condition and the environment
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