Phonon lifetime investigation of anharmonicity and thermal conductivity of UO2 by neutron scattering and theory.

Inelastic neutron scattering measurements of individual phonon lifetimes and dispersion at 295 and 1200 K have been used to probe anharmonicity and thermal conductivity in UO2. They show that longitudinal optic phonon modes carry the largest amount of heat, in contrast to past simulations and that the total conductivity demonstrates a quantitative correspondence between microscopic and macroscopic phonon physics. We have further performed first-principles simulations for UO2 showing semiquantitative agreement with phonon lifetimes at 295 K, but larger anharmonicity than measured at 1200 K.

Prevalence of Staphylococcus aureus carriage by young Malaysian footballers during indoor training.

BACKGROUND: Research has shown that athletes are carriers of Staphylococcus aureus during physical activity. OBJECTIVE: To estimate the mean total plate count of S aureus carried by footballers before and after training at an indoor venue. METHODS: Forty Malay and 20 Indian students volunteered to participate. There was also a control group consisting of 40 Malay and 20 Indian students who were not active. The experimental group were active footballers who had played at school or club level. The subjects were healthy and free of skin infection. The experiment was divided into three sessions, with 20 subjects present at each. At each session, the subjects trained for one hour. Swabs were taken from the skin, nose, and ear before and after training. For the control group, swabs were taken only once from the skin, nose, and ear. The swabs were subjected to biochemical tests and then streaked and cultured aerobically in Baird Parker agar plates for 24 hours at 37 degrees C. Black colonies with a clear zone were presumed to be S aureus, and the mean total plate count of the colonies was estimated. Gram staining, catalase, coagulase slide, coagulase tube, acetoin production, o-nitrophenyl beta-D-galactopyranoside (ONPG), and mannitol fermentation tests were used to confirm the colonies as S aureus. A haemolysin test was conducted with human blood to confirm haemolytic activity. RESULTS: All subjects in the experimental group were carrying S aureus both before and after training. The estimated mean total counts of colonies from the skin, ear, and nose for the Malays before training were 33, 71, and 312 respectively. Counts after training were 21, 44, and 452 respectively. The results for the Indians were 72, 80, and 309 respectively before training and 55, 200, and 466 respectively after training. The positive results for Gram staining, catalase, coagulase slide, coagulase tube, acetoin production, ONPG, and mannitol fermentation tests were 100%, 96%, 95%, 95%, 93%, 93%, and 90% respectively. All subjects in the control group were also carrying S aureus. CONCLUSIONS: All of the players were carriers of S aureus during training. The decrease in total count from the skin for both races may be due to lysozyme activity lysing the bacterial cells. Contamination of the environment with these bacteria may have increased the estimated total plate count in the nose. The experimental group face a higher risk of infection because of lower immunity during training and higher rate of injuries compared with the control group.

Adaptive development and structure in the radius of the odontocete

Radii of the smaller toothed-whales are striking examples, developmentally and structurally, of accommodation to the requirements for secondary marine adaptation. This was studied, with cleared whole mounts and histological sections from the fetus and with radiographs of adult bones, in the beluga (Delphinapterus leucas) and pilot whales (Globicephala melaena). Radii are flattened, semistreamline in cross-section and, like the ulnae, articulate (synchondrosis) end-on with the humerus. Distal to the elbow, the flipper is amuscular. Radial development is characterized by a high ratio of transverse to longitudinal growth rates, by a slow, irregular process of endochondral ossification, by retention of endochondral spicules in lieu of a medullary cavity, and by a deep deposit of variably spongy periosteal bone. Ultimately, the radius has medial and lateral concentrations of bone a lesser central density mimetic of a mechanically advantageous box-beam. Throughout life, however, the history of the bone is revealed by proximal and distal endochondral cones and surrounding masses of periosteal bone, distinguishable in lateral radiographs. From this geometry, and from cross-sections, it is clear that the radius grows eccentrically, i.e., circumferential increments to epiphyseal plates, and to periosteal surface, are greatest on the posterior margin, intermediate along medial and lateral sides and least on the anterior margin. In the ulna, growth is in the opposite sense. Opposite margins of the elongating antibrachial bones thus move apart while adjacent margins hold relatively the same positions. Eccentric growth maintains the ratio of major to minor axes in the cross-section. The Arctic beluga radius is more dense, and radiographs reveal within it the outline of the neonatal radius. Beyond this outline, variable porosity suggests periodic growth (AU)