Multiphase smoothed-particle hydrodynamics

We adapt the smoothed-particle hydrodynamics (SPH) technique to allow a multiphase fluid in which SPH particles of widely differing density may be freely intermixed. Applications include modelling of galaxy formation and cooling flows

Silicon Based Light Emission by Avalanche Breakdown of Shallow p+/n+ Junctions

The objective of this study was to develop and demonstrate a technology for producing optical signals on a VLSI chip using only standard silicon processing techniques. The design of the process requires shallow p+/n+ junctions to minimize the high absorption inherent in silicon for λ\u3c 8SOnm and to obtain low reversed biased voltages for avalanche break down of the p+/n+junction due to impact-ionization. The effects of doping and device geometry on the visible luminescence of reverse biased Si p+In+ junction diodes has been investigated. Each diode designed has a unique design incorporating sharp edges that promote high fields that aid the onset of break down. The p+ doping was varied while other processing parameters were held constant. All vertical junction diodes had excellent diode characteristics but no light emission was observed. Lateral junction diodes had typical reverse breakdown voltages of between 6 and 7 volts while certain devices of set geometry broke down rather sharply at 4 volts with light emission. Intensity and breakdown characteristics seemed to correlate with magnitude of p+ dose and device geometry

Two-Electron Photon Emission From Metallic Quantum Wells

Unusual emission of visible light is observed in scanning tunneling microscopy of the quantum well system Na on Cu(111). Photons are emitted at energies exceeding the energy of the tunneling electrons. Model calculations of two-electron processes which lead to quantum well transitions reproduce the experimental fluorescence spectra, the quantum yield, and the power-law variation of the intensity with the excitation current.Comment: revised version, as published; 4 pages, 3 figure

Calving Difficulty in Beef Cattle: Part II

Many cattlemen believe reducing dietary energy during late pregnancy will decrease fetal size resulting in improved calving ease, whereas increasing energy will increase fetal size leading to a higher incidence of dystocia. Generally speaking, research has shown that lowering the energy allowance will decrease birth weight but will not significantly reduce dystocia. At MARC, Hereford and Angus 2-year-old heifers were fed three levels of energy (10.8, 13.7 or 17 .0 lb TDN/head/day) for 90 days prior to calving. Increasing the level of dietary energy resulted in increased birth weight but not increased dystocia; in fact, the incidence of calving difficulty was lower in the medium and high energy groups than in the low energy group

Calving Difficulty in Beef Cattle: Part I

Calving difficulty (dystocia) can increase calf losses, cow mortality, and veterinary and labor costs, as well as delay return to estrus, and lower conception rates. In two studies at the U.S. Meat Animal Research Center (MARC), Clay Center, Nebraska, calf losses within 24 hours of birth averaged 4 percent for those born with little or no assistance compared to 16 percent for those requiring assistance. Calf mortality increased by a 0.35 percent per pound increase in birth weight. In a Hereford herd at the U.S. Livestock and Range Research Station. Miles City, Montana, 57 percent of all calf losses were reported to be due to dystocia

Quantifying, Projecting, and Addressing India's Hidden Hunger

<p>It is estimated that more than two billion people suffer from ‘hidden hunger’ (micronutrient malnutrition) globally, with nearly half living in India. Despite being highlighted as one the most cost-effective investments for human development, progress on addressing micronutrient deficiencies (MiND) has been slowing. The severe social, health, and economic costs of MiND in India should make it a top priority for domestic governance and international donors alike. This study, for the first time, maps food system pathways from crop production through to household-level food availability, for a range of key vitamins, minerals, and amino acids. Results suggest widespread (>80% total Indian population) risk of deficiencies in calcium, vitamin A, B₁₂, folate, in addition to lysine limitation, with more localized deficiencies (<25% population) in iron, zinc, and vitamin B₆. These deficiencies are the result of a combination of a monotonous cereal-dominated diet lacking in diversity, and overall insufficient food intake. This approach also allowed for “MiND by micronutrient” scenario analysis to 2030, to identify potential intervention points in the food system and the capacity of these interventions to address deficiency. Scenario analysis to 2030 and 2050 indicates that, although increased availability of animal-based products, reduction of supply chain losses, and close to maximum (90%) attainable yields could make some contribution to addressing Indian MiND, additional intervention strategies will be essential. Recommendations for intervention in the short (urgent), near-term (2030), and long-term (2050) have been formulated based on this analysis.</p