Photoemission study of the electronic structure of CdTe

Photoemission study of electronic structure of cadmium telluride single crystal

The influence of hypercapnia and the infaunal brittlestar <i>Amphiura filiformis</i> on sediment nutrient flux – will ocean acidification affect nutrient exchange?

Rising levels of atmospheric carbon dioxide and the concomitant increased uptake of this by the oceans is resulting in hypercapnia-related reduction of ocean pH. Research focussed on the direct effects of these physicochemical changes on marine invertebrates has begun to improve our understanding of impacts at the level of individual physiologies. However, CO₂-related impairment of organisms' contribution to ecological or ecosystem processes has barely been addressed. The burrowing ophiuroid <i>Amphiura filiformis</i>, which has a physiology that makes it susceptible to reduced pH, plays a key role in sediment nutrient cycling by mixing and irrigating the sediment, a process known as bioturbation. Here we investigate the role of <i>A. filiformis</i> in modifying nutrient flux rates across the sediment-water boundary and the impact of CO₂- related acidification on this process. A 40 day exposure study was conducted under predicted pH scenarios from the years 2100 (pH 7.7) and 2300 (pH 7.3), plus an additional treatment of pH 6.8. This study demonstrated strong relationships between <i>A. filiformis</i> density and cycling of some nutrients; <iA. filiformis</i> activity increases the sediment uptake of phosphate and the release of nitrite and nitrate. No relationship between <i>A. filiformis</i> density and the flux of ammonium or silicate were observed. Results also indicated that, within the timescale of this experiment, effects at the individual bioturbator level appear not to translate into reduced ecosystem influence. However, long term survival of key bioturbating species is far from assured and changes in both bioturbation and microbial processes could alter key biogeochemical processes in future, more acidic oceans

Cyclotron Analysis of Australian Atmospheric Contamination before and after the 1974 French Nuclear Tests in the Pacific

Atmospheric particulates collected around East Coast Australian cities and Port Moresby, just before and after the French Atomic Test Series of 1974 in the Pacific, have been analysed by proton activation using the Melbourne University Cyclotron. A number of elements, namely S, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Se and Hg, ranging in concentrations from .001 ug/m3 to up to 3.27 ug/m3 have been detected. The changes observed in the concentrations of these elements in the two sets of samples, taken just before and just after the Atomic Tests, are attributed to Synoptic rather than Nuclear Fall-Out effects

Concentrations of Insulin-Like Growth Factor-I in Blood and Ovarian Follicular Fluid of Cattle Selected for Twins

Recent studies have implicated insulin-like growth factor I (IGF-I) as an intraovarian regulator of follicular growth and differentiation. Therefore, we investigated the possibility that cattle selected for twin births may have increased concentrations of IGF-I within the ovarian follicle and(or) in peripheral blood. The estrous cycles of 14 cows with histories of producing twins and 12 control monotocous cows were synchronized with 35 mg of prostaglandin F2α (PGF2α). Blood and follicular fluid were collected 48-50 h post-administration of PGF2α. (follicular phase of the estrous cycle). Concentrations of IGF-I were measured by RJA after acid-ethanol treatment of serum or follicular fluid. Twin-producing cows had a greater (p \u3c 0.05) number of large (\u3e4 mm) follicles and 47% greater (p \u3c 0.05) concentrations of IGF-I in peripheral blood than control cows. Cattle selected for high twinning frequency also had greater (p \u3c 0.05) concentrations of IGF-I (±SE) in the two largest follicles than control (unselected) cows (327 ± 28 vs. 243 ± 29 ng/ml). IGF-I concentrations in pooled small (1-3.9 mm) follicles were less (p \u3c 0.05) than in large follicles but did not differ between control and twin-producing cattle. In addition, the percentage of IGF-I concentrations measured in follicular fluid to that of serum was lower (P \u3c 0.05) in small follicles than in large follicles, and was greater (p \u3c0.05) in large follicles of control (93.2 ± 5.3%) than twin-producing (76.2 ± 4.4%) cattle. Moreover, concentrations of IGF-I in serum and follicular fluid were correlated positively (r = 0.69, p \u3c 0.01). Concentrations of estradiol and progesterone in follicular fluid of small or large follicles did not differ between control and twin-producing cattle. Collectively, the present study provides evidence suggesting that natural twinning in cattle is associated with increased concentrations of IGF-I in both blood and follicular fluid. These data are consistent with the hypothesis that IGF-I plays a role in the regulation of folliculogenesis and is a mediator of a genetic component of multiple ovulations in cattle

Impulsive phase flare energy transport by large-scale Alfven waves and the electron acceleration problem

The impulsive phase of a solar flare marks the epoch of rapid conversion of energy stored in the pre-flare coronal magnetic field. Hard X-ray observations imply that a substantial fraction of flare energy released during the impulsive phase is converted to the kinetic energy of mildly relativistic electrons (10-100 keV). The liberation of the magnetic free energy can occur as the coronal magnetic field reconfigures and relaxes following reconnection. We investigate a scenario in which products of the reconfiguration - large-scale Alfven wave pulses - transport the energy and magnetic-field changes rapidly through the corona to the lower atmosphere. This offers two possibilities for electron acceleration. Firstly, in a coronal plasma with beta < m_e/m_p, the waves propagate as inertial Alfven waves. In the presence of strong spatial gradients, these generate field-aligned electric fields that can accelerate electrons to energies on the order of 10 keV and above, including by repeated interactions between electrons and wavefronts. Secondly, when they reflect and mode-convert in the chromosphere, a cascade to high wavenumbers may develop. This will also accelerate electrons by turbulence, in a medium with a locally high electron number density. This concept, which bridges MHD-based and particle-based views of a flare, provides an interpretation of the recently-observed rapid variations of the line-of-sight component of the photospheric magnetic field across the flare impulsive phase, and offers solutions to some perplexing flare problems, such as the flare "number problem" of finding and resupplying sufficient electrons to explain the impulsive-phase hard X-ray emission.Comment: 31 pages, 6 figure

Characterization of Hidden Airframe Corrosion by Time-Resolved Infrared Radiometry (TRIR)

Since hidden corrosion is expected to be the primary factor limiting the service life of military and civilian aircraft, the problem of detection of hidden corrosion needs to be solved to allow for life extension. A quantitative thermographic NDE technique for the characterization of hidden corrosion is under development along with supporting theoretical analysis. In earlier work [1,2] we have shown that the technique of time-resolved infrared radiometry (TRIR) is an effective method for quantitatively detecting coating thickness variations and for characterizing the degree of coating disbonding in terms of equivalent air gaps. In this paper we examine the applicability of TRIR techniques to the characterization of corrosion damage in airframes by investigating plate specimens of 2024-T3 aluminum with both milled defects and corroded regions produced by an accelerated corrosion test.</p

How primary care can contribute to good mental health in adults.

The need for support for good mental health is enormous. General support for good mental health is needed for 100% of the population, and at all stages of life, from early childhood to end of life. Focused support is needed for the 17.6% of adults who have a mental disorder at any time, including those who also have a mental health problem amongst the 30% who report having a long-term condition of some kind. All sectors of society and all parts of the NHS need to play their part. Primary care cannot do this on its own. This paper describes how primary care practitioners can help stimulate such a grand alliance for health, by operating at four different levels - as individual practitioners, as organisations, as geographic clusters of organisations and as policy-makers