Optical investigations of the chemical pressurized EuFe2(As1-xPx)2: an s-wave superconductor with strong interband interaction

Superconducting EuFe2(As0.82P0.18)2 single crystals are investigated by infrared spectroscopy in a wide frequency range. Below Tc=28K a superconducting gap forms at 2\Delta_{0} = 9.5 meV = 3.8 k_B T_c causing the reflectivity to sharply rise to unity at low frequency. In the range of the gap the optical conductivity can be perfectly described by BCS theory with an $s$-wave gap and no nodes. From our analysis of the temperature dependent conductivity and spectral weight at T>T_c, we deduce an increased interband coupling between hole- and electron-sheets on the Fermi surface when $T$ approaches T_c

An Evaluative Study of the United States Cooperative Extension Service\u27s Role in Bridging the Digital Divide

Raising the level of digital inclusion by increasing the number of Americans using the technology tools of the digital age is a vitally important national goal (U.S. Department of Commerce, 2000). The study reported here focused on Extension administrators throughout the United States to gauge their opinion concerning the role of Extension in bridging the digital divide. It was found that a perceived digital divide existed. Extension administrators expressed that Extension was an adequate mechanism to combat this societal dilemma. Recommendations included establishing strategic partnerships with local community groups to provide technology access and training for residents

Self-Consistent Response of a Galactic Disk to an Elliptical Perturbation Halo Potential

We calculate the self-consistent response of an axisymmetric galactic disk perturbed by an elliptical halo potential of harmonic number m = 2, and obtain the net disk ellipticity. Such a potential is commonly expected to arise due to a galactic tidal encounter and also during the galaxy formation process. The self-gravitational potential corresponding to the self-consistent, non-axisymmetric density response of the disk is obtained by inversion of Poisson equation for a thin disk. This response potential is shown to oppose the perturbation potential, because physically the disk self-gravity resists the imposed potential. This results in a reduction in the net ellipticity of the perturbation halo potential in the disk plane. The reduction factor denoting this decrease is independent of the strength of the perturbation potential, and has a typical minimum value of 0.75 - 0.9 for a wide range of galaxy parameters. The reduction is negligible at all radii for higher harmonics (m > or = 3) of the halo potential. (abridged).Comment: 26 pages (LaTex- aastex style), 3 .eps figures. To appear in the Astrophysical Journal, Vol. 542, Oct. 20, 200

Dark matter dominance at all radii in the superthin galaxy UGC 7321

We model the shape and density profile of the dark matter halo of the low surface brightness, superthin galaxy UGC 7321, using the observed rotation curve and the HI scale height data as simultaneous constraints. We treat the galaxy as a gravitationally coupled system of stars and gas, responding to the gravitational potential of the dark matter halo. An isothermal halo of spherical shape with a core density in the range of 0.039 - 0.057 M_sun/pc^3 and a core radius between 2.5 - 2.9 kpc, gives the best fit to the observations for a range of realistic gas parameters assumed. We find that the best-fit core radius is only slightly higher than the stellar disc scale length (2.1 kpc), unlike the case of the high surface brightness galaxies where the halo core radius is typically 3-4 times the disc scale length of the stars. Thus our model shows that the dark matter halo dominates the dynamics of the low surface brightness, superthin galaxy UGC 7321 at all radii, including the inner parts of the galaxy.Comment: 18 pages, 3 figures, Accepted for publication in New Astronom

Improved HIV testing coverage after scale-up of antiretroviral therapy programs in urban Zambia: Evidence from serial hospital surveillance

Background: We evaluated changing HIV testing coverage and prevalence rates before and after expanding city-wide antiretroviral therapy (ART) programs in Lusaka, Zambia.Methods: We conducted serial cross-sectional surveys on the University Teaching Hospital medical ward to assess HIV prevalence among inpatients of unknown status in 2003 and 2006. Willing participants received counseling and dual HIV rapid tests. We compared the proportion of inpatients receiving their test results in 2003 (off-the-ward testing) to 2006 (on-the-ward).Results: In 2003, none of 103 inpatients knew their HIV status or took ART; 99.0% (102/103) agreed to testing. In 2006, 49.3% (99 of 201) patients knew they were HIV-infected and were on ART; of those with unknown status, 98.0% (100/102) agreed to testing. In 2003, only 54.9% (56/102) received posttest counseling and 98.2% (55/56) learned their status. In 2006, 99.0% (99/100) received post-test counseling and 99.1% (98 of 99) learned their status. In 2003, 62.8% (64 of 102) of status- unknown inpatients who agreed to testing were seropositive by dual rapid test, compared to 48.0% (48 of 100) of status-unknown inpatients in 2006. When including inpatients who already knew their seropositive status plus those unknowns who tested seropositive, the proportion of inpatients that was seropositive in 2006 was 73.1% (147 of 201), higher than in 2003.Conclusions: After ART program expansion, inpatients in 2006 were far more likely than their 2003 counterparts to know their HIV status and to be taking ART. In both years, 63-73% of medical inpatients were HIV-infected and 98.5% of inpatients agreed to testing. On-the-ward testing in 2006 avoided the 2003 problem of patient discharge before learning of their test results. Hospital-based HIV testing is an essential clinical service in high prevalence settings and can serve further as a surveillance system to help track the community impact of outpatient AIDS services in Africa.Keywords: HIV, testing, surveillance, Zambi

Stochastic Programming Model in Least Cost Feed Formulation for Lactating Cattle

A conventional linear programming model (LPM) for feed formulation of lactating cattle will overlook the variation in feed components. LPM only considers the mean composition of feed values, regardless of variations, the confidence in satisfying the nutrient need falls to 50%. Whereas the stochastic model (SM), which takes into account both the mean and variation of feed composition and provides 90-99% confidence in meeting the nutrient need. In present work, we have proposed SM for least-cost feed formulation of lactating cattle where the variation in the composition of nutrients like crude protein (CP), Calcium (Ca) and Phosphorus (P) in the feedstuff are considered. Data provided by the National Research Council (2001) are the basis for the current analysis. These SMs are resolved using M.S. Excel's Generalized Reduced Gradient (GRG) nonlinear and LINGO's Nonlinear solver, and the results are compared to LPM; the feed formulated by SM (90 % and 99 %) has the lowest cost when compared to LPM. Nutrients estimated by LPM, SM by GRG nonlinear, and SM by Nonlinear solver utilized for feed formulation had no significant differences as (p>0.05).  When compared to LPM, the stochastic model is a better technique, particularly when dealing with nutrient variation

Thermal quenching of luminescence in erbium doped semiconductors

The nature of the temperature dependence of luminescence intensity from Er+ ions in GaInAsP, Si, InP, GaAs, AlGaAs, ZnTe, as observed by Favennecet al [1] has been examined in terms of a double exponential model. The smaller activation energy is found to be 58-100 meV, characteristic of a localized energy barrier at the Er+ centre while the higher activation energy is approximately 0.8E g attributed to an Auger non-radiative process of carrier excitation into bands. This model has been found to describe the observed temperature dependences with reasonably good agreement

Statistics of leading digits leads to unification of quantum correlations

We show that the frequency distribution of the first significant digits of the numbers in the data sets generated from a large class of measures of quantum correlations, which are either entanglement measures, or belong to the information-theoretic paradigm, exhibit a universal behaviour. In particular, for Haar uniformly simulated arbitrary two-qubit states, we find that the first-digit distribution corresponding to a collection of chosen computable quantum correlation quantifiers tend to follow the first-digit law, known as the Benford's law, when the rank of the states increases. Considering a two-qubit state which is obtained from a system governed by paradigmatic spin Hamiltonians, namely, the XY model in a transverse field, and the XXZ model, we show that entanglement as well as information theoretic measures violate the Benford's law. We quantitatively discuss the violation of the Benford's law by using a violation parameter, and demonstrate that the violation parameter can signal quantum phase transitions occurring in these models. We also comment on the universality of the statistics of first significant digits corresponding to appropriate measures of quantum correlations in the case of multipartite systems as well as systems in higher dimensions.Comment: v1: 11 pages, 5 figures, 2 tables; v2: 11 pages, 6 figures, 2 tables, new results added, extended version of the published pape