Scanning Capacitance Spectroscopy on n\u3csup\u3e+\u3c/sup\u3e-p Asymmetrical Junctions in Multicrystalline Si Solar Cells

We report on a scanning capacitance spectroscopy (SCS) study on the n+-p junction of multicrystalline silicon solar cells. We found that the spectra taken at space intervals of ∼10 nm exhibit characteristic features that depend strongly on the location relative to the junction. The capacitance-voltage spectra exhibit a local minimum capacitance value at the electrical junction, which allows the junction to be identified with ∼10-nm resolution. The spectra also show complicated transitions from the junction to the n-region with two local capacitance minima on the capacitance-voltage curves; similar spectra to that have not been previously reported in the literature. These distinctive spectra are due to uneven carrier-flow from both the n- and p-sides. Our results contribute significantly to the SCS study on asymmetrical junctions

Closed Spaces in Cosmology

This paper deals with two aspects of relativistic cosmologies with closed (compact and boundless) spatial sections. These spacetimes are based on the theory of General Relativity, and admit a foliation into space sections S(t), which are spacelike hypersurfaces satisfying the postulate of the closure of space: each S(t) is a 3-dimensional, closed Riemannian manifold. The discussed topics are: (1) A comparison, previously obtained, between Thurston's geometries and Bianchi-Kantowski-Sachs metrics for such 3-manifolds is here clarified and developed. (2) Some implications of global inhomogeneity for locally homogeneous 3-spaces of constant curvature are analyzed from an observational viewpoint.Comment: 20 pages, 6 figures, revised version of published paper. In version 2: several misprints corrected, 'redshifting' in figures improved. Version 3: a few style corrections; couple of paragraphs in subsection 2.4 rewritten. Version 4: figures 5 and 6 corrrecte

Casimir energy density in closed hyperbolic universes

The original Casimir effect results from the difference in the vacuum energies of the electromagnetic field, between that in a region of space with boundary conditions and that in the same region without boundary conditions. In this paper we develop the theory of a similar situation, involving a scalar field in spacetimes with compact spatial sections of negative spatial curvature.Comment: 10 pages. Contribution to the "Fifth Alexander Friedmann International Seminar on Gravitation and Cosmology," Joao Pessoa, Brazil, 2002. Revised version, with altered Abstract and one new referenc

Synthesis, photophysical and electrochemical properties of π-conjugated pyrene based down-shifting molecules with fluorinated aryl groups

ABSTRACT: Pyrene molecule, with excellent photophysical properties (strong absorption cross section, excellent emission properties and a long-excited state lifetime), excellent thermal and photochemical stability, has been widely used as a building block for the synthesis of pyrene-based fluorophores for optoelectronic applications. In this work, we report the synthesis of two series of pyrene-pi-A compounds, series I (3-6) and II (10-13), in which nitro, cyano, cyanoacrylonitrile and cyanoacrylic acid as electron acceptor groups are connected to the pyrene core via aryl or fluoroaryl pi-conjugating bridges. The incorporation of fluorine atom on the pi-extension bridge cause a slightly red-shift at emission wavelength (lambda em) in solution and polymethylmethacrylate (PMMA) films and in-crease the Stokes shift due to greater stabilization of molecular orbitals in the excited state, especially for series I. Solvatochromic measurements and theoretical computational studies suggest a higher intramolecular charge transfer in the excited state for series II when compared to series I due to their stronger electron acceptor moieties. All pyrene derivatives are stable and exhibited initial mass loss at temperature above 200 degrees C. The good photophysical and thermal properties of the synthesized pyrene derivatives, associated with high molar ab-sorption coefficients in the UV spectrum and good fluorescence emission in the range of 430-480 nm (series I) and 505-567 nm (series II) in PMMA films, make them possible candidates for organic light-emitting diode (OLED) and luminescent down-shifting (LDS) layers for stable perovskite solar cells, respectively.info:eu-repo/semantics/publishedVersio

Antimicrobial susceptibility of Gram-positive bacteria isolated from European medical centres: results of the Daptomycin Surveillance Programme (2002-2004)

The antimicrobial susceptibility patterns of 9322 contemporary (2002-2004) Gram-positive bacterial isolates collected from 31 medical centres in 14 countries in Europe were evaluated by broth microdilution methods according to CLSI guidelines. the isolates collected comprised Staphylococcus aureus (4842 isolates), coagulase-negative staphylococci (CoNS; 1942 isolates), Enterococcus faecalis (1147 isolates), Enterococcus faecium (391 isolates), beta-haemolytic streptococci (660 isolates) and viridans group streptococci (340 isolates). the organisms were tested against daptomycin and more than 20 comparator agents in Mueller-Hinton broth, supplemented with calcium to 50 mg/L when testing daptomycin. Overall, methicillin (oxacillin) resistance rates were 26.7% and 77.0% for S. aureus (MRSA) and CoNS, respectively, and the vancomycin resistance rate among enterococci was 6.1%. MRSA rates varied from 0.6% in Sweden to 40.2-43.0% in Belgium, Greece, Ireland, the UK and Israel, and VRE rates varied from 0% in Switzerland to 21.2% in Ireland. More than 99.9% of isolates tested were considered susceptible to daptomycin according to breakpoints established by the United States Food and Drug Administration and the CLSI. Daptomycin was active against all Gram-positive species, with the highest MIC being 2, 8, 0.5 and 2 mg/L for staphylococci, enterococci, beta-haemolytic streptococci and viridans group streptococci, respectively. Daptomycin activity was not influenced adversely by resistance to other agents among staphylococci or enterococci. This novel lipopeptide (daptomycin) appears to be an excellent alternative therapeutic option for serious infections caused by multidrug-resistant Gram-positive organisms isolated in Europe.JMI Labs Inc, N Liberty, IA 52317 USAUniversidade Federal de São Paulo, São Paulo, BrazilTufts Univ, Sch Med, Boston, MA 02111 USAUniversidade Federal de São Paulo, São Paulo, BrazilWeb of Scienc

Exploring Halo Substructure with Giant Stars: Spectroscopy of Stars in the Galactic Anticenter Stellar Structure

To determine the nature of the recently discovered, ring-like stellar structure at the Galactic anticenter, we have collected spectra of a set of presumed constituent M giants selected from the 2MASS point source catalog. Radial velocities have been obtained for stars spanning ~100 degrees, exhibiting a trend in velocity with Galactic longitude and an estimated dispersion of 20 +/- 4 km/sec. A mean metallicity [Fe/H] = -0.4 +/- 0.3 measured for these stars combines with previous evidence from the literature to suggest a population with a significant metallicity spread. In addition, a curious alignment of at least four globular clusters of lower mean metallicity is noted to be spatially and kinematically consistent with this stellar distribution. We interpret the M giant sample position and velocity variation with Galactic longitude as suggestive of a satellite galaxy currently undergoing tidal disruption in a non-circular, prograde orbit about the Milky Way.Comment: (1) University of Virginia, 4 pages, 3 figures, accepted for publication in The Astrophysical Journal Letter

BioWorkbench: A High-Performance Framework for Managing and Analyzing Bioinformatics Experiments

Advances in sequencing techniques have led to exponential growth in biological data, demanding the development of large-scale bioinformatics experiments. Because these experiments are computation- and data-intensive, they require high-performance computing (HPC) techniques and can benefit from specialized technologies such as Scientific Workflow Management Systems (SWfMS) and databases. In this work, we present BioWorkbench, a framework for managing and analyzing bioinformatics experiments. This framework automatically collects provenance data, including both performance data from workflow execution and data from the scientific domain of the workflow application. Provenance data can be analyzed through a web application that abstracts a set of queries to the provenance database, simplifying access to provenance information. We evaluate BioWorkbench using three case studies: SwiftPhylo, a phylogenetic tree assembly workflow; SwiftGECKO, a comparative genomics workflow; and RASflow, a RASopathy analysis workflow. We analyze each workflow from both computational and scientific domain perspectives, by using queries to a provenance and annotation database. Some of these queries are available as a pre-built feature of the BioWorkbench web application. Through the provenance data, we show that the framework is scalable and achieves high-performance, reducing up to 98% of the case studies execution time. We also show how the application of machine learning techniques can enrich the analysis process