Solar Cell Production Jumps 50 Percent in 2007

Production of photovoltaics (PV) jumped to 3,800 megawatts worldwide in 2007, up an estimated 50 percent over 2006. At the end of the year, according to preliminary data, cumulative global production stood at 12,400 megawatts, enough to power 2.4 million U.S. homes. Growing by an impressive average of 48 percent each year since 2002, PV production has been doubling every two years, making it the world's fastest-growing energy source.Photovoltaics, which directly convert sunlight into electricity, include both traditional, polysilicon-based solar cell technologies and new thin-film technologies. Thin-film manufacturing involves depositing extremely thin layers of photosensitive materials on glass, metal, or plastics. While the most common material currently used is amorphous silicon, the newest technologies use non-silicon-based materials such as cadmium telluride.A key force driving the advancement of thin-film technologies is a polysilicon shortage that began in April 2004. In 2006, for the first time, more than half of polysilicon production went into PVs instead of computer chips. While thin films are not as efficient at converting sunlight to electricity, they currently cost less and their physical flexibility makes them more versatile than traditional solar cells. Led by the United States, thin film grew from 4 percent of the market in 2003 to 7 percent in 2006. Polysilicon supply is expected to match demand by 2010, but not before thin film grabs 20 percent of the market. The top five PV-producing countries are Japan, China, Germany, Taiwan, and the United States. Recent growth in China is most astonishing: after almost tripling its PV production in 2006, it is believed to have more than doubled output in 2007. With more than 400 PV companies, China's market share has exploded from 1 percent in 2003 to over 18 percent today. Having eclipsed Germany in 2007 to take the number two spot, China is now on track to become the number one PV producer in 2008. The United States, which gave the world the solar cell, has dropped from third to fifth place as a solar cell manufacturer since 2005, overtaken by China in 2006 and Taiwan in 2007. See data at www.earthpolicy.org/Indicators/Solar/2007_data.htm

Tsunami response at Wake Island: A model study

The amplitude response to periodic plane waves incident upon an undistorted model of Wake Island on a scale of 57,500:1 was determined for a number of frequencies covering the long-wave portion of the wave spectrum and from three different directions…

Wind stress on an artificial pond

The wind-induced slope of the surface in an 800-foot model-yacht pond has been measured to a relative accuracy of 5 x 10-7. This slope is proportional to the sum of the surface and bottom stresses…

Explosion-generated waves in water of variable depth

This study shows that the theory of geometric optics adequately predicts the behavior of a dispersive wave system radiating from a large chemical explosion over sloping bottom topography. The phase and amplitude of an equivalent wave train (reconstructed from the observed data for uniform depth equal to that at the explosion site) are shown to be consistent with the phase and amplitude predicted by theory for the wave system produced by an initial parabolic crater in the water...

Increasing Extension Volunteer Knowledge and Preparedness with Youth Protection Training Across Program Areas

The University of Georgia (UGA) has a training requirement for adults working with youth. To meet this requirement for Georgia 4-H and Extension Master Gardener volunteers, a standardized online training module was created and delivered across program areas. Volunteers were surveyed to evaluate training effectiveness and experience. Understanding of UGA youth protocols and service preparedness increased after training for both volunteer groups, though preparedness may be affected by life stage, engagement in youth service roles, and/or comfort with virtual training. The module was considered accessible and convenient by respondents, thus providing a successful approach for offering trainings across program areas

Development of a carbon fibre composite active mirror: Design and testing

Carbon fibre composite technology for lightweight mirrors is gaining increasing interest in the space- and ground-based astronomical communities for its low weight, ease of manufacturing, excellent thermal qualities and robustness. We present here first results of a project to design and produce a 27 cm diameter deformable carbon fibre composite mirror. The aim was to produce a high surface form accuracy as well as low surface roughness. As part of this programme, a passive mirror was developed to investigate stability and coating issues. Results from the manufacturing and polishing process are reported here. We also present results of a mechanical and thermal finite element analysis, as well as early experimental findings of the deformable mirror. Possible applications and future work are discussed.Comment: Accepted by Optical Engineering. Figures 1-7 on http://www.star.ucl.ac.uk/~sk/OEpaper_files

Comparative study of gp130 cytokine effects on corticotroph AtT-20 cells - Redundancy or specificity of neuroimmunoendocrine modulators?

Objective: This comparative in vitro study examined the effects of all known gp130 cytokines on murine corticotroph AtT-20 cell function. Methods: Cytokines were tested at equimolar concentrations from 0.078 to 10 nM. Tyrosine phosphorylation of the signal transducer and activator of transcription ( STAT) 3 and STAT1, the STAT-dependent suppressor of cytokine signaling (SOCS)-3 promoter activity, SOCS-3 gene expression, STAT-dependent POMC promoter activity and adrenocorticotropic hormone ( ACTH) secretion were determined. Results: Leukemia inhibitory factor (LIF), human oncostatin M (OSM) and cardiotrophin (CT)-1 (LIFR/gp130 ligands), as well as ciliary neurotrophic factor ( CNTF) and novel neurotrophin1/B-cell stimulating factor-3 (CNTFRalpha/LIFR/gp130 ligands) are potent stimuli of corticotroph cells in vitro. In comparison, interleukin (IL)-6 (IL-6R/gp130 ligand) and IL-11 (IL-11R/gp130 ligand) exhibited only modest direct effects on corticotrophs, while murine OSM (OSMR/gp130 ligand) showed no effect. Conclusion: (i) CNTFR complex ligands are potent stimuli of corticotroph function, comparable to LIFR complex ligands; (ii) IL-6 and IL-11 are relatively weak direct stimuli of corticotroph function; (iii) differential effects of human and murine OSM suggest that LIFR/gp130 (OSMR type I) but not OSMR/gp130 (OSMR type II) are involved in corticotroph signaling. (iv) CT-1 has the hitherto unknown ability to stimulate corticotroph function, and (v) despite redundant immuno-neuroendocrine effects of different gp130 cytokines, corticotroph cells are preferably activated through the LIFR and CNTFR complexes. Copyright (C) 2004 S. Karger AG, Basel

From stellar to planetary composition: Galactic chemical evolution of Mg/Si mineralogical ratio

The main goal of this work is to study element ratios that are important for the formation of planets of different masses. We study potential correlations between the existence of planetary companions and the relative elemental abundances of their host stars. We use a large sample of FGK-type dwarf stars for which precise Mg, Si, and Fe abundances have been derived using HARPS high-resolution and high-quality data. A first analysis of the data suggests that low-mass planet host stars show higher [Mg/Si] ratios, while giant planet hosts present [Mg/Si] that is lower than field stars. However, we found that the [Mg/Si] ratio significantly depends on metallicity through Galactic chemical evolution. After removing the Galactic evolution trend only the difference in the [Mg/Si] elemental ratio between low-mass planet hosts and non-hosts was present in a significant way. These results suggests that low-mass planets are more prevalent around stars with high [Mg/Si]. Our results demonstrate the importance of Galactic chemical evolution and indicate that it may play an important role in the planetary internal structure and composition.Comment: Accepted by A&A (Letter to the Editor