Spectrophotovoltaic orbital power generation

A system with 1000 : 1 concentration ratio is defined, using a cassegrain telescope as the first stage concentration (270 x) and compound parabolic concentrators (CPC) for the second stage concentration of 4.7 x for each spectral band. Using reported state of the art (S.O.A.) solar cells device parameters and considering structural losses due to optics and beamsplitters, the efficiencies of one to four cell systems were calculated with efficiencies varying from approximately 22% to 30%. Taking into account cost of the optics, beamsplitter, radiator, and the cost of developing new cells the most cost effective system is the GaAs/Si system

Planes of isotropic Poisson's ratio in anisotropic crystalline solids

It is shown that loading directions can exist in all single crystals for which Poisson’s ratio is isotropic in the plane transverse to the loading direction. The body diagonals and the cube axes of cubic crystals, the four-fold axis in tetragonal crystals and the six-fold axis in hexagonal crystals are examples of such loading directions. However, these loading directions do not necessarily just lie only along high rotational symmetry axes. A new three-dimensional “anisotropy surface” is introduced to represent the degree of anisotropy of the Poisson’s ratio within the plane normal to a loading direction for a particular choice of single crystal.This work is part of the Early Career Research (ECR) grant award (Ref. no.: ECR/2016/001953) funded by Science and Engineering Research Board (SERB) of Department of Science and Technology (DST), India. Dr. Suresh Neelakantan acknowledges the support

Benchmark full configuration-interaction calculations on HF and NH2

Full configuration-interaction (FCI) calculations are performed at selected geometries for the 1-sigma(+) state of HF and the 2-B(1) and 2-A(1) states of NH2 using both DZ and DZP gaussian basis sets. Higher excitations become more important when the bonds are stretched and the self-consistent field (SCF) reference becomes a poorer zeroth-order description of the wave function. The complete active space SCF - multireference configuration-interaction (CASSCF-MRCI) procedure gives excellent agreement with the FCI potentials, especially when corrected with a multi-reference analog of the Davidson correction

Barro's fertility equations: the robustness of the role of female education and income

Barro and Lee (1994) and Barro and Sala-i-Martin (1995) find that real per-capita GDP and both male and female education have important effects on fertility in their cross-country empirical studies. In order to assess the robustness of their results, their estimated models are subjected to specification and diagnostic testing, the effects on the model of using the improved Barro and Lee (1996) cross-country data on educational attainment of the population aged 15 and over are examined, and the different specifications used by Barro and Lee and by Barro and Sala-i-Martin compared. The results obtained suggest that their fertility equations do not perform well in terms of diagnostic testing, and are very sensitive to the use of different vintages of the educational attainment proxies and of the Summers-Heston cross-country income data. A robust explanation of fertility, to link with empirical growth equations, has, therefore, not yet been found; further work is required in this area

Species identity dominates over environment in shaping the microbiota of small mammals

The mammalian gut microbiota is considered pivotal to host fitness, yet the determinants of community composition remain poorly understood. Laboratory studies show that environmental factors, particularly diet, are important, while comparative work emphasises host genetics. Here, we compare the influence of host genetics and the environment on the microbiota of sympatric small mammal species (mice, voles, shrews) across multiple habitats. While sharing a habitat caused some microbiota convergence, the influence of species identity dominated. In all three host genera examined, an individual's microbiota was more similar to conspecifics living elsewhere than to heterospecifics at the same site. Our results suggest this species‐specificity arises in part through host‐microbe codiversification. Stomach contents analysis suggested that diet also shapes the microbiota, but where diet is itself influenced by species identity. In this way, we can reconcile the importance of both diet and genetics, while showing that species identity is the strongest predictor of microbiota composition

The Sources of b-Quarks at the Tevatron and their Correlations

The leading-log order QCD hard scattering Monte-Carlo models of HERWIG, ISAJET, and PYTHIA are used to study the sources of b-quarks at the Tevatron. The reactions responsible for producing b and bbar quarks are separated into three categories; flavor creation, flavor excitation, and parton-shower/fragmentation. Flavor creation corresponds to the production of a b-bbar pair by gluon fusion or by annihilation of light quarks, while flavor excitation corresponds to a b or bbar quark being knocked out of the initial-state by a gluon or a light quark or antiquark. The third source occurs when a b-bbar pair is produced within a parton shower or during the fragmentation process of a gluon or a light quark or antiquark (includes gluon splitting). The QCD Monte-Carlo models indicate that all three sources of b-quarks are important at the Tevatron and when combined they qualitatively describe the inclusive cross-section data. Correlations between the b and bbar quark are very different for the three sources and can be used to isolate the individual contributions.Comment: RevTex4, 14 pages, 20 figures, submitted to Phys. Rev.

A New Technique for Finding Needles in Haystacks: A Geometric Approach to Distinguishing Between a New Source and Random Fluctuations

We propose a new test statistic based on a score process for determining the statistical significance of a putative signal that may be a small perturbation to a noisy experimental background. We derive the reference distribution for this score test statistic; it has an elegant geometrical interpretation as well as broad applicability. We illustrate the technique in the context of a model problem from high-energy particle physics. Monte Carlo experimental results confirm that the score test results in a significantly improved rate of signal detection.Comment: 5 pages, 4 figure

Dimethyl sulphide in some Australian red wines

DMS levels in Cabernet Sauvignon wine from the Coonawarra area of southeast South Australia were shown to vary from 42 to 910 μg l-1. Results indicate that the levels are not dependent on age but rather vary from vintage to vintage. This study does not discount the development of DMS with bottle age as it is an 'historical' survey but suggests that the levels of DMS are vintage related and may depend on viticultural practices and vinification techniques. The odour threshold for DMS in Cabernet Sauvignon was 0.07 μl l-1 (60μg l -1)