Comparing nanowire, multijunction, and single junction solar cells in the presence of light trapping

In this paper we quantify the constraints and opportunities for radial junctionnanowiresolar cells, compared to single junction and multijunction solar cells, when light trapping is included. Both nanowire and multijunction designs are reliant on a very low level of traps in the junction region, and without this, single junction designs are optimal. If low trap density at the junction can be achieved, multijunction cells lead to higher efficiencies than nanowire cells for a given diffusion length, except in the case of submicron diffusion lengths. Thus the radial junctionstructure is not in itself an advantage in general, though if nanowires allow faster deposition or better light trapping than other structures they could still prove advantageous.This work was supported by the Australian Research Council

Feline hypersomatotropism and acromegaly tumorigenesis: a potential role for the AIP gene

Acromegaly in humans is usually sporadic, however up to 20% of familial isolated pituitary adenomas are caused by germline sequence variants of the aryl-hydrocarbon-receptor interacting protein (AIP) gene. Feline acromegaly has similarities to human acromegalic families with AIP mutations. The aim of this study was to sequence the feline AIP gene, identify sequence variants and compare the AIP gene sequence between feline acromegalic and control cats, and in acromegalic siblings. The feline AIP gene was amplified through PCR using whole blood genomic DNA from 10 acromegalic and 10 control cats, and 3 sibling pairs affected by acromegaly. PCR products were sequenced and compared with the published predicted feline AIP gene. A single nonsynonymous SNP was identified in exon 1 (AIP:c.9T > G) of two acromegalic cats and none of the control cats, as well as both members of one sibling pair. The region of this SNP is considered essential for the interaction of the AIP protein with its receptor. This sequence variant has not previously been reported in humans. Two additional synonymous sequence variants were identified (AIP:c.481C > T and AIP:c.826C > T). This is the first molecular study to investigate a potential genetic cause of feline acromegaly and identified a nonsynonymous AIP single nucleotide polymorphism in 20% of the acromegalic cat population evaluated, as well as in one of the sibling pairs evaluated

Searching for "monogenic diabetes" in dogs using a candidate gene approach

BACKGROUND: Canine diabetes is a common endocrine disorder with an estimated breed-related prevalence ranging from 0.005% to 1.5% in pet dogs. Increased prevalence in some breeds suggests that diabetes in dogs is influenced by genetic factors and similarities between canine and human diabetes phenotypes suggest that the same genes might be associated with disease susceptibility in both species. Between 1-5% of human diabetes cases result from mutations in a single gene, including maturity onset diabetes of the adult (MODY) and neonatal diabetes mellitus (NDM). It is not clear whether monogenic forms of diabetes exist within some dog breeds. Identification of forms of canine monogenic diabetes could help to resolve the heterogeneity of the condition and lead to development of breed-specific genetic tests for diabetes susceptibility. RESULTS: Seventeen dog breeds were screened for single nucleotide polymorphisms (SNPs) in eighteen genes that have been associated with human MODY/NDM. Six SNP associations were found from five genes, with one gene (ZFP57) being associated in two different breeds. CONCLUSIONS: Some of the genes that have been associated with susceptibility to MODY and NDM in humans appear to also be associated with canine diabetes, although the limited number of associations identified in this study indicates canine diabetes is a heterogeneous condition and is most likely to be a polygenic trait in most dog breeds. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/2052-6687-1-8) contains supplementary material, which is available to authorized users

Surface plasmon enhanced silicon solar cells

Thin-film solar cells have the potential to significantly decrease the cost of photovoltaics. Light trapping is particularly critical in such thin-film crystalline silicon solar cells in order to increase light absorption and hence cell efficiency. In this article we investigate the suitability of localized surface plasmons on silvernanoparticles for enhancing the absorbance of silicon solar cells. We find that surface plasmons can increase the spectral response of thin-film cells over almost the entire solar spectrum. At wavelengths close to the band gap of Si we observe a significant enhancement of the absorption for both thin-film and wafer-based structures. We report a sevenfold enhancement for wafer-based cells at λ=1200 nm and up to 16-fold enhancement at λ=1050 nm for 1.25 μm thin silicon-on-insulator (SOI) cells, and compare the results with a theoretical dipole-waveguide model. We also report a close to 12-fold enhancement in the electroluminescence from ultrathin SOI light-emitting diodes and investigate the effect of varying the particle size on that enhancement.S. Pillai would like to acknowledge the UNSW Faculty of Engineering Research Scholarship. K.R. Catchpole acknowledges the support of an Australian Research Council fellowship

Constraining the Nature of the Galactic Center X-ray Source Population

We searched for infrared counterparts to the cluster of X-ray point sources discovered by Chandra in the Galactic Center Region (GCR). While the sources could be white dwarfs, neutron stars, or black holes accreting from stellar companions, their X-ray properties are consistent with magnetic Cataclysmic Variables, or High Mass X-ray Binaries (HMXB) at low accretion-rates. A direct way to decide between these possibilities and hence between alternative formation scenarios is to measure or constrain the luminosity distribution of the companions. Using infrared (J, H, K, Br-gamma) imaging, we searched for counterparts corresponding to typical HMXB secondaries: spectral type B0V with K<15 at the GCR. We found no significant excess of bright stars in Chandra error circles, indicating that HMXBs are not the dominant X-ray source population, and account for fewer than 10% of the hardest X-ray sources.Comment: 4 pages, 3 figures, 1 table, accepted in ApJ Letters for publicatio

The visibility of the Galactic bulge in optical surveys. Application to the Gaia mission

The bulge is a region of the Galaxy which is of tremendous interest for understanding Galaxy formation. However, measuring photometry and kinematics in it raises several inherent issues, like high extinction in the visible and severe crowding. Here we attempt to estimate the problem of the visibility of the bulge at optical wavelengths, where large CCD mosaics allow to easily cover wide regions from the ground, and where future astrometric missions are planned. Assuming the Besancon Galaxy model and high resolution extinction maps, we estimate the stellar density as a function of longitude, latitude and apparent magnitude and we deduce the possibility of reaching and measuring bulge stars. The method is applied to three Gaia instruments, the BBP and MBP photometers, and the RVS spectrograph. We conclude that, while in the BBP most of the bulge will be accessible, in the MBP there will be a small but significant number of regions where bulge stars will be detected and accurately measured in crowded fields. Assuming that the RVS spectra may be extracted in moderately crowded fields, the bulge will be accessible in most regions apart from the strongly absorbed inner plane regions, because of high extinction, and in low extinction windows like the Baades's window where the crowding is too severe.Comment: 11 pages, 9 figures, accepted for publication in A&A, latex using A&A macro