14,029 research outputs found

    A method of assessing the quality of pharmaceutical market and industry reports as a source to study access to medicines

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    This repository item contains a single issue of the Health and Development Discussion Papers, an informal working paper series that began publishing in 2002 by the Boston University Center for Global Health and Development. It is intended to help the Center and individual authors to disseminate work that is being prepared for journal publication or that is not appropriate for journal publication but might still have value to readers.Market and industry reports can be useful in studying access to medicines from a pharmaceutical market perspective. However, many market and industry reports lack some or much of the information required to conduct analyses to study access to medicines and are often not transparent in their data sources and research methodologies. The instrument developed in this study, titled the Pharmaceutical Market and Industry Report Assessment Tool (PIRAT), assesses the quality of pharmaceutical market and industry reports, specifically focusing on the needs of public health researchers, and includes criteria describing the content and quality of the market reports. The assessment tool generates an unweighted score indicating the relative strengths and weaknesses of reports

    New records of marine invertebrates from São Tomé and Príncipe (Eastern tropical Atlantic)

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    The following species are recorded from the coasts of São Tomé and Príncipe for the first time: the ciliate Zoothamnium niveum, the black coral Antipathella wollastoni, the zoanthid Isaurus tubercularis, and the shrimp Latreutes fucorum. The presence of the black coral Tanacetipathes spinescens and of the shrimp Cinetorhynchus rigens is confirmed. The presence of the crab Platypodiella picta at São Tome Island is confirmed and a possibly undescribed species of Platypodiella is recorded from Príncipe Island. Mistaken records of Stichopathes lutkeni are corrected: the species at São Tomé and Príncipe is Stichopathes occidentalis.info:eu-repo/semantics/publishedVersio

    Two-chamber lattice model for thermodiffusion in polymer solutions

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    When a temperature gradient is applied to a polymer solution, the polymer typically migrates to the colder regions of the fluid as a result of thermal diffusion (Soret effect). However, in recent thermodiffusion experiments on poly(ethylene-oxide) (PEO) in a mixed ethanol/water solvent it is observed that for some solvent compositions the polymer migrates to the cold side, while for other compositions it migrates to the warm side. In order to understand this behavior, we have developed a two-chamber lattice model approach to investigate thermodiffusion in dilute polymer solutions. For a short polymer chain in an incompressible, one-component solvent we obtain exact results for the partitioning of the polymer between a warm and a cold chamber. In order to describe mixtures of PEO, ethanol, and water, we have extended this simple model to account for compressibility and hydrogen bonding between PEO and water molecules. For this complex system, we obtain approximate results for the composition in the warmer and cooler chambers that allow us to calculate Soret coefficients for given temperature, pressure, and solvent composition. The sign of the Soret coefficient is found to change from negative (polymer enriched in warmer region) to positive (polymer enriched in cooler region) as the water content of the solution is increased, in agreement with experimental data. We also investigate the temperature dependence of the Soret effect and find that a change in temperature can induce a change in the sign of the Soret coefficient. We note a close relationship between the solvent quality and the partitioning of the polymer between the two chambers, which may explain why negative Soret coefficients for polymers are so rarely observed.Comment: 12 pages, 8 figure

    Band structure of boron doped carbon nanotubes

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    We present {\it ab initio} and self-consistent tight-binding calculations on the band structure of single wall semiconducting carbon nanotubes with high degrees (up to 25 %) of boron substitution. Besides a lowering of the Fermi energy into the valence band, a regular, periodic distribution of the p-dopants leads to the formation of a dispersive ``acceptor''-like band in the band gap of the undoped tube. This comes from the superposition of acceptor levels at the boron atoms with the delocalized carbon π\pi-orbitals. Irregular (random) boron-doping leads to a high concentration of hybrids of acceptor and unoccupied carbon states above the Fermi edge.Comment: 4 pages, 2 figure

    Ab initio calculation of the GG peak intensity of graphene: Combined study of the laser and Fermi energy dependence and importance of quantum interference effects

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    We present the results of a diagrammatic, fully ab initio calculation of the GG peak intensity of graphene. The flexibility and generality of our approach enables us to go beyond the previous analytical calculations in the low-energy regime. We study the laser and Fermi energy dependence of the GG peak intensity and analyze the contributions from resonant and non-resonant electronic transitions. In particular, we explicitly demonstrate the importance of quantum interference and non-resonant states for the GG peak process. Our method of analysis and computational concept is completely general and can easily be applied to study other materials as well.Comment: 10 pages, 5 figure

    First record of the Sculptured Mitten Lobster Parribacus antarcticus (Crustacea, Decapoda, Scyllaridae) from the Cabo Verde Islands (eastern Atlantic)

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    The lobster genus Parribacuscontains six living and one fossil species (Holthuis 1991; Chan 2010; Nyborg & Garassino 2017). In the Atlantic Ocean, only one living species is known, Parribacus antarcticus(Lund, 1793); it has been recorded in the western Atlantic from Florida to Brazil and recently also from the mid-Atlantic island of Ascension (Brown et al.2016). It is nocturnal and is often found hiding in crevices during daytime (Holthuis 1991). We here note the presence of Parribacus antarcticusat the Cabo Verde Islands, the first record of the species from the eastern Atlantic.info:eu-repo/semantics/publishedVersio

    Lecanogaster gorgoniphila, a new species of clingfish (Teleostei: Gobiesocidae) from São Tomé and Principe, eastern Atlantic Ocean

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    The clingfish Lecanogaster gorgoniphila new species, an unusual species associated with gorgonians, is described on the basis of 7 specimens and colour photographs from São Tomé Island, São Tomé and Principe, eastern Atlantic Ocean. The species is small, probably not exceeding 28 mm total length; it is characterized by having 4-5 dorsal-fin rays, 3-4 anal-fin rays, 21-23 pectoral-fin rays, and 11-14 principal caudal-fin rays; 12-14 rakers on third gill arch, very small, partially fused; papillae in centre of pelvic disk forming a round patch; pelvic disc region B with 5-6 rows of papillae; head relatively short, its length 2.4-3.4 in SL, and relatively narrow, its width 4.5-7.4 in SL; colouration of head and body variable in life, usually dorsally reddish white, ventrally rose, with eight bright red bars with scattered white spots. The new species is compared with other species of the eastern Atlantic genera Lecanogaster and Diplecogaster; a key to the species of the genus Lecanogaster Briggs, 1957 is presented.info:eu-repo/semantics/publishedVersio

    Apletodon gabonensis, a new species of clingfish (Teleostei: Gobiesocidae) from Gabon, eastern Atlantic Ocean

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    The clingfish Apletodon gabonensis sp. nov. is described on the basis of seven specimens and colour photographs from Gabon, eastern Atlantic Ocean. The species is small, apparently not exceeding 20 mm total length; it is characterized by having 5 dorsal-fin rays, 4-5 anal-fin rays, 25-27 pectoral-fin rays, head width in males 2.6-4.7 in SL, anus in males with urogenital papilla present but not pronounced; snout long, broad, anteriorly truncate in male, narrower and rather pointed in female; preorbital length 1.8-3.8 in head length; conspicuous maxillary barbel absent in both sexes; disc with 10-12 rows of papillae in region A, 5 rows of papillae in region B, and 5-7 rows of papillae in region C. The new species is compared with the other species of the genus; a key to the males of the 6 known species of the eastern Atlantic genus Apletodon is presented.info:eu-repo/semantics/publishedVersio

    The phonon dispersion of graphite revisited

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    We review calculations and measurements of the phonon-dispersion relation of graphite. First-principles calculations using density-functional theory are generally in good agreement with the experimental data since the long-range character of the dynamical matrix is properly taken into account. Calculations with a plane-wave basis demonstrate that for the in-plane optical modes, the generalized-gradient approximation (GGA) yields frequencies lower by 2% than the local-density approximation (LDA) and is thus in better agreement with experiment. The long-range character of the dynamical matrix limits the validity of force-constant approaches that take only interaction with few neighboring atoms into account. However, by fitting the force-constants to the ab-initio dispersion relation, we show that the popular 4th-nearest-neighbor force-constant approach yields an excellent fit for the low frequency modes and a moderately good fit (with a maximum deviation of 6%) for the high-frequency modes. If, in addition, the non-diagonal force-constant for the second-nearest neighbor interaction is taken into account, all the qualitative features of the high-frequency dispersion can be reproduced and the maximum deviation reduces to 4%. We present the new parameters as a reliable basis for empirical model calculations of phonons in graphitic nanostructures, in particular carbon nanotubes.Comment: 26 pages, 7 figures, to appear in Solid State Com
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