Some considerations on silicone oil in high-current and energy-disconnecting mechanisms

Silicone oil is considered inflammable. The dissociation products generated by an electric arc under silicone oil are known to form a highly explosive mixture with air. We calculate the arc energy required for dissociation to be 32 kJ per liter of gas mixture at standard pressure and temperature. We calculate the arc voltage gradient at a pressure of 50 atm and current density of 1 kA/mm/sup 2/ to be 0.5 kV/cm, resulting in an arc voltage of several kV, depending on the arc length. In a multikiloampere arc, the resulting arc power is likely to cause a pressure of many atmospheres in a shock wave

Annual Changes In A Bird Assembly On Artificial Perches: Implications For Ecological Restoration In A Subtropical Agroecosystem

Artificial perches are used in tropical forest restoration projects to increase the dispersal of seeds into restored areas. The ability of perches to enhance seed deposition depends on their ability to attract seed dispersing birds, as well as the correlation between the season of bird visits to perches and the phenology of fruit production in adjacent forests. Using data collected from a large-scale restoration project, we characterized the community of birds that utilize artificial perches over the course of one year. We hypothesized that the structure of a bird assemblage that uses artificial perches is affected by seasonal variation. We aimed to describe the richness, abundance and diversity of a bird assemblage on artificial perches in a subtropical Atlantic forest restoration experiment in Southern Brazil. Richness and abundance estimates of the avian fauna were obtained from eight artificial perches placed in four experimental plots (B2 y-old). Parameters of richness and abundance were compared using ANOVA. The bird assemblage was described using SHE analysis [richness (S), diversity (H’) and evenness (E)], with additional estimates of occurrence and dominance. In total, 451 records of 32 ± 3.16 SD species were obtained. Thraupidae was the most numerous family (nine species, 28.12% of the total). Richness and abundance varied seasonally and were highest during spring and summer. Five migratory species of flycatchers were recorded between spring and early autumn. Perches were ineffective in attracting specialized frugivorous birds, emphasizing that seed dispersal tends to be carried out primarily by generalist omnivores in the initial phase of forest regeneration. © 2016, Universidade Estadual de Campinas UNICAMP. All rights reserved.16

Genetic variation for Ca, Mg, and K concentrations in Agropyrons and Psathyrostachys

We had three goals in this series of studies. We wished to 1) determine the extent of genetic variability and broad sense heritability for Ca, Mg and K concentrations in these forage grasses, 2) obtain an estimate of the relative magnitude of genotype x environment interaction, and 3) develop a breeding and selection program for lines having reduced tetany potential (RTP) indices

Using plant breeding and genetics to overcome the incidence of grass tetany

Plant breeders developing cultivars to minimize the hazards of grass tetany are concentrating largely on increasing herbage Mg concentrations in cool-season (C3) grasses. Significant genetic variation has been found for Mg, Ca and K concentrations within C3 grass species studied to date. For most C3 forage grass species, heritability estimates are highest for Mg, slightly lower for Ca and lowest for K concentrations. The largest genotype x environmental interactions are found for K values, whereas small environmental effects have been observed for Mg and Ca values. No C3 forage grass cultivar has been developed to date that would eliminate hypomagnesemia. Grass breeders need to develop more experimental C3 plant populations that have high Mg and Ca concentrations. These experimental synthetics with genetically altered mineral concentrations need to be fed to ruminants susceptible to grass tetany to determine whether grass tetany can be eliminated or reduced. Limited feeding trials using ruminants show that improved animal performance can be expected when feeding forage grasses bred for higher Mg concentrations

Heme iron from meat and risk of colorectal cancer: a meta-analysis and a review of the mechanisms involved

Red meat and processed meat intake is associated with a risk of colorectal cancer, a major cause of death in affluent countries. Epidemiological and experimental evidence supports the hypothesis that heme iron present in meat promotes colorectal cancer. This meta-analysis of prospective cohort studies of colon cancer reporting heme intake included 566,607 individuals and 4,734 cases of colon cancer. The summary relative risk of colon cancer was 1.18 [95%C.I.: 1.06-1.32] for subjects in the highest category of heme iron intake compared with those in the lowest category. Epidemiological data thus show a suggestive association between dietary heme and risk of colon cancer. The analysis of experimental studies in rats with chemically-induced colon cancer showed that dietary hemoglobin and red meat consistently promote aberrant crypt foci, a putative pre-cancer lesion. The mechanism is not known, but heme iron has a catalytic effect on (i) the endogenous formation of carcinogenic N-nitroso compounds and (ii) the formation of cytotoxic and genotoxic aldehydes by lipoperoxidation. A review of evidence supporting these hypotheses suggests that both pathways are involved in heme iron toxicit

Nonclassical correlations of photon number and field components in the vacuum state

It is shown that the quantum jumps in the photon number n from zero to one or more photons induced by backaction evasion quantum nondemolition measurements of a quadrature component x of the vacuum light field state are strongly correlated with the quadrature component measurement results. This correlation corresponds to the operator expectation value which is equal to one fourth for the vacuum even though the photon number eigenvalue is zero. Quantum nondemolition measurements of a quadrature component can thus provide experimental evidence of the nonclassical operator ordering dependence of the correlations between photon number and field components in the vacuum state.Comment: 13 pages, 3 figures, corrections of omissions in equations (6) and (25). To be published in Phys. Rev.

Genetic variability for mineral element concentration of crested wheatgrass forage

Grass tetany is a complex metabolic disorder that causes substantial livestock production losses and deaths in temperate regions of the world. It is caused by low levels of Mg or an imbalance of K, Ca, and Mg in forage consumed by animals. Development of grasses with improved mineral balance would be an economical means of minimizing losses from this malady. This study was conducted to determine if genetic variability exists among crested wheatgrasses, Agropyron cristatum (L.) Gaertner and A. desertorum (Fisher ex Link) Schultes, for forage Mg, Ca, K, Fe, Zn, Mn, Cu, Na, and P concentrations. Forage of spaced plants of 10 diverse crested wheatgrass strains was harvested from replicated plots at Lincoln and Alliance, NE, which differ markedly in climate, and analyzed for these minerals. There were genetic differences among strains over locations for Ca, Mg, and Fe concentration in the forage. There were differences among strains within locations but not over locations for K. Strain differences in Zn, Mn, Cu, Na, and P concentrations of the forage were not significant (P > 0.05) when averaged over locations. Calcium and Mg were positively correlated (r = 0.40). These results indicate that it should be possible to breed crested wheatgrass with increased Mg and Ca concentrations in its forage, thus reducing grass tetany potential

Forage quality, mineral constituents, and performance of beef yearlings grazing two crested wheatgrasses

In the central Great Plains, crested wheatgrasses (Agropyron cristatum (L.) Gaetner and A. desertorium (Fischer ex Link) Schultes] are best utilized for early spring and late fall grazing. The principal objective of this study was to determine if beef (Bos taurus L.) yearlings grazing 'Ruff' (A. cristatum) during the spring grazing season had higher average daily gains and gains per hectare than cattle grazing `Nordan' (A. desertorum). These cultivars were evaluated in grazing trials (four replications) in eastern Nebraska in 1985, 1986, and 1987. The 0.8-ha pastures were seeded in the fall of 1983 on a Typic Argiudoll soil and were fertilized annually with 68 to 90 kg N ha-1. Grazing was for 6 wk each spring by yearling steers with a beginning average weight of 250 kg. Averaged over 3 yr, Ruff produced higher gains per hectare than Nordan (272 vs 245 kg ha-1) probably because it produced more herbage because of its better persistence. At the end of the trial, the averge basal cover of Ruff and Nordan were 21 and 6%, respectively. Three-year mean average daily gains were Ruff = 1.28 vs. Nordan = 1.34 kg d-1, which were unexpected, because Ruff generally had higher forage quality as measured by an array of parameters. Ruff forage had a higher, less desirable grass tetany ratio [K/(Mg +Ca)) than Nordan (2.6 vs. 2.3) averaged over 3 yr. Cattle grazing Ruff had lower blood serum Mg levels than cattle grazing Nordan (15.4 vs. 16.2 mg L-1, both of which were below the hypomagnesemia threshold of 18 mg L-1. This condition may have reduced intake and animal gains. These results indicate the need for evaluating pasture and range grass cultivars under grazing conditions

Measurement of W Polarisation at LEP

The three different helicity states of W bosons produced in the reaction e+ e- -> W+ W- -> l nu q q~ at LEP are studied using leptonic and hadronic W decays. Data at centre-of-mass energies \sqrt s = 183-209 GeV are used to measure the polarisation of W bosons, and its dependence on the W boson production angle. The fraction of longitudinally polarised W bosons is measured to be 0.218 \pm 0.027 \pm 0.016 where the first uncertainty is statistical and the second systematic, in agreement with the Standard Model expectation