Energy analysis of organic crop systems. Impact of intensification level.

This study reveals a wide variability in the major parameters of the energy analysis applied to 44 four-year-long organic crop sequences. The intensification level of the systems in terms of the use or nonuse of organic fertilisation on cereals and of irrigation on summer crops (mainly pulses) is largely responsible for this variability. Average energy consumption ranges from 5 000 to 12 270 MJ/ha/year depending on the intensification level. Energy production varies from 35 500 to 43 950 MJ/ha/year. Since energy consumption and production both vary in the same direction with the degree of intensification, the energy gain is stable at an average value of 29300 MJ/ha/year. Energy efficiency decreases from 7.1 MJ/MJ for unfertilised and unirrigated crop sequences, to 3.5 MJ/MJ for fertilised and irrigated sequences, where soy and faba bean are among the major crops

Composição corporal e exigências líquidas de proteína e energia de bovinos de quatro grupos genéticos terminados em confinamento.

Objetivou-se neste estudo avaliar a composição corporal e as exigências para crescimento de bovinos de quatro grupos genéticos em confinamento. Utilizou-se a metodologia de abate comparativo, com delineamento inteiramente ao acaso, com quatro tratamentos: Nelore (NE), ½ Aberdeen Angus + ½ Nelore (AN), ½ Canchim + ½ Nelore (CN) e ½ Simental + ½ Nelore (SN). Quarenta e sete animais castrados, com média de 22 meses de idade e peso em jejum de 310 kg, foram confinados por 101 dias. A dieta experimental continha 13,34% de proteína bruta (PB) e 71,81% de nutrientes digestíveis totais (NDT). A composição do corte da 9a-10a-11a costelas foi utilizada para estimar a composição do corpo vazio. Bovinos AN (428 kg) e SN (410 kg) não diferiram quanto ao peso final de corpo vazio, que foi semelhante também entre os animais CN, NE e SN (389, 390 e 410 kg, respectivamente). Animais AN tiveram maior proporção de gordura no corte das costelas, porém menor proporção de músculo.A menor porcentagem de ossos no corte das costelas foi observada nos animais da raça Nelore. Os grupos AN e SN tiveram maior proporção de extrato etéreo (EE) e menor porcentagem de água no corpo vazio no momento do abate. Animais AN, NE e SN não diferiram quanto à taxa de deposição de energia (6,06, 5,20 e 5,80 Mcal/dia, respectivamente). O grupo AN não diferiu dos grupos CN e SN quanto à proporção de EE na composição do ganho de peso do corpo vazio. Bovinos SN apresentaram maior exigência de proteína (0,164 kg/kg de ganho de peso vazio - GPV) e os animais AN e CN, o menor valor (0,140 e 0,142 kg/kg de GPV, respectivamente). Animais AN tiveram a maior exigência líquida de energia para ganho (4,685 Mcal/kg de GPVz). Palavras-chave: bovinos de corte, composição corporal, cruzament

Muon capture by 3He nuclei followed by proton and deuteron production

The paper describes an experiment aimed at studying muon capture by ${}^{3}\mathrm{He}$ nuclei in pure ${}^{3}\mathrm{He}$ and $\mathrm{D}_2 + {}^{3}\mathrm{He}$ mixtures at various densities. Energy distributions of protons and deuterons produced via $\mu^-+{}^{3}\mathrm{He}\to p+n+n + \nu_{\mu }$ and $\mu^-+{}^{3} \mathrm{He} \to d+n + \nu_{\mu}$ are measured for the energy intervals $10 - 49$ MeV and $13 - 31$ MeV, respectively. Muon capture rates, $\lambda_\mathrm{cap}^p (\Delta E_p)$ and $\lambda_\mathrm{cap}^d (\Delta E_d)$ are obtained using two different analysis methods. The least--squares methods gives $\lambda_\mathrm{cap}^p = (36.7\pm 1.2) {s}^{- 1}$, $\lambda_\mathrm{cap}^d = (21.3 \pm 1.6) {s}^{- 1}$. The Bayes theorem gives $\lambda_\mathrm{cap}^p = (36.8 \pm 0.8) {s}^{- 1}$, $\lambda_\mathrm{cap}^d = (21.9 \pm 0.6) {s}^{- 1}$. The experimental differential capture rates, $d\lambda_\mathrm{cap}^p (E_p) / dE_p$ and $d\lambda_\mathrm{cap}^d (E_d) / dE_d$, are compared with theoretical calculations performed using the plane--wave impulse approximation (PWIA) with the realistic NN interaction Bonn B potential. Extrapolation to the full energy range yields total proton and deuteron capture rates in good agreement with former results.Comment: 17 pages, 13 figures, accepted for publication in PR

Induced pseudoscalar coupling of the proton weak interaction

The induced pseudoscalar coupling $g_p$ is the least well known of the weak coupling constants of the proton's charged--current interaction. Its size is dictated by chiral symmetry arguments, and its measurement represents an important test of quantum chromodynamics at low energies. During the past decade a large body of new data relevant to the coupling $g_p$ has been accumulated. This data includes measurements of radiative and non radiative muon capture on targets ranging from hydrogen and few--nucleon systems to complex nuclei. Herein the authors review the theoretical underpinnings of $g_p$, the experimental studies of $g_p$, and the procedures and uncertainties in extracting the coupling from data. Current puzzles are highlighted and future opportunities are discussed.Comment: 58 pages, Latex, Revtex4, prepared for Reviews of Modern Physic

The (muon^-,muon^+) conversion in nuclei as a probe of new physics

A detailed study of the muonic analogue of neutrinoless double beta decay, (muon^-,muon^+) conversion, has been carried out for the A=44 nuclear system. We studied several lepton number violating (LNV) mechanisms potentially triggering this process: exchange by light and heavy Majorana neutrinos as well as exchange by supersymmetric particles participating in R-parity violating interactions. The nuclear structure has been taken into account within the renormalized Quasiparticle Random Phase Approximation method. To our knowledge, this is the first realistic treatment of nuclear structure aspects of the (muon^-,muon^+) conversion. We estimated the rate of this process utilizing the existing experimental constraints on the parameters of the underlying LNV interactions and conclude that the (muon^-,muon^+) conversion is hardly detectable in the near future experiments.Comment: 23 pages, RevTex, 3 Postscript figure

Depth-specific fluctuations of gene expression and protein abundance modulate the photophysiology in the seagrass Posidonia oceanica

Here we present the results of a multiple organizational level analysis conceived to identify acclimative/adaptive strategies exhibited by the seagrass Posidonia oceanica to the daily fluctuations in the light environment, at contrasting depths. We assessed changes in photophysiological parameters, leaf respiration, pigments, and protein and mRNA expression levels. The results show that the diel oscillations of P. oceanica photophysiological and respiratory responses were related to transcripts and proteins expression of the genes involved in those processes and that there was a response asynchrony between shallow and deep plants probably caused by the strong differences in the light environment. The photochemical pathway of energy use was more effective in shallow plants due to higher light availability, but these plants needed more investment in photoprotection and photorepair, requiring higher translation and protein synthesis than deep plants. The genetic differentiation between deep and shallow stands suggests the existence of locally adapted genotypes to contrasting light environments. The depth-specific diel rhythms of photosynthetic and respiratory processes, from molecular to physiological levels, must be considered in the management and conservation of these key coastal ecosystems.Portuguese funds from FCT - Foundation for Science and Technology [UID/Multi/04326/2013]; SZN PhD fellowship via the Open University; ESF COST Action Seagrass Productivity: From Genes to Ecosystem Management [ES0906]info:eu-repo/semantics/publishedVersio

Calculs sur la capture des muons par les noyaux

We obtain a general formula for the capture probability of a negative muon by a nucleus, using spherical tensors. The non-relativistic approximation has been used and the nuclear matrix elements were calculated by the choice of an independant particle shell model. We have applied these results to the capture probability by sonie nuclei near calcium in order to evaluate the ratio of Gamow-Teller to Fermi coupling.Nous avons établi une formule générale de probabilité de capture du muon négatif par un noyau en utilisant les tenseurs sphériques. L'approximation non relativiste a été utilisée et les éléments de matrices nucléaires ont été explicitées en prenant un modèle en couche à une particule. Nous avons appliqué les résultats ainsi trouvés à la probabilité de capture du muon par des noyaux voisins du calcium en vue d'évaluer l'importance relative du couplage de Gamow-Teller

New approach to transitions from bound to continuum three-nucleon states: the case of muon capture by a triton

A new approach to the problem of the transition of an A=3 ground state to scattering states via a weakly acting Hamiltonian is presented; calculations are made feasible with realistic nucleon-nucleon potentials. Muon capture by 3H leading to three neutrons is taken as a test case and is carried through till numerical results are obtained