3,846 research outputs found

    A Precise Distance to IRAS 00420+5530 via H2O Maser Parallax with the VLBA

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    We have used the VLBA to measure the annual parallax of the H2O masers in the star-forming region IRAS 00420+5530. This measurement yields a direct distance estimate of 2.17 +/- 0.05 kpc (<3%), which disagrees substantially with the standard kinematic distance estimate of ~4.6 kpc (according to the rotation curve of Brand and Blitz 1993), as well as most of the broad range of distances (1.7-7.7 kpc) used in various astrophysical analyses in the literature. The 3-dimensional space velocity of IRAS 00420+5530 at this new, more accurate distance implies a substantial non-circular and anomalously slow Galactic orbit, consistent with similar observations of W3(OH) (Xu et al., 2006; Hachisuka et al. 2006), as well as line-of-sight velocity residuals in the rotation curve analysis of Brand and Blitz (1993). The Perseus spiral arm of the Galaxy is thus more than a factor of two closer than previously presumed, and exhibits motions substantially at odds with axisymmetric models of the rotating Galaxy.Comment: 33 pages, 12 figures; Accepted by ApJ (to appear March 2009

    Competitive aminal formation during the synthesis of a highly soluble, isopropyl-decorated imine porous organic cage.

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    The synthesis of a new porous organic cage decorated with isopropyl moieties (CC21) was achieved from the reaction of triformylbenzene and an isopropyl functionalised diamine. Unlike structurally analogous porous organic cages, its synthesis proved challenging due to competitive aminal formation, rationalised using control experiments and computational modelling. The use of an additional amine was found to increase conversion to the desired cage

    Exciton polaritons in a cylindrical microcavity with an embedded quantum wire

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    Exciton-light coupling in cylindrical microcavities containing quantum wires has been treated by means of classical electrodynamics within the nonlocal dielectric response model. A typical anticrossing behavior of quasi-one-dimensional exciton-polariton modes has been obtained, as well as the weak-coupling–strong-coupling threshold. Effects of the nonradiative damping of the exciton resonance in the quantum wire on the optical response of the microcavity structure have been analyzed

    Viral metagenomic analysis of feces of wild small carnivores

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    Background: Recent studies have clearly demonstrated the enormous virus diversity that exists among wild animals. This exemplifies the required expansion of our knowledge of the virus diversity present in wildlife, as well as the potential transmission of these viruses to domestic animals or humans. Methods: In the present study we evaluated the viral diversity of fecal samples (n = 42) collected from 10 different species of wild small carnivores inhabiting the northern part of Spain using random PCR in combination with next-generation sequencing. Samples were collected from American mink (Neovison vison), European mink (Mustela lutreola), European polecat (Mustela putorius), European pine marten (Martes martes), stone marten (Martes foina), Eurasian otter (Lutra lutra) and Eurasian badger (Meles meles) of the family of Mustelidae; common genet (Genetta genetta) of the family of Viverridae; red fox (Vulpes vulpes) of the family of Canidae and European wild cat (Felis silvestris) of the family of Felidae. Results: A number of sequences of possible novel viruses or virus variants were detected, including a theilovirus, phleboviruses, an amdovirus, a kobuvirus and picobirnaviruses. Conclusions: Using random PCR in combination with next generation sequencing, sequences of various novel viruses or virus variants were detected in fecal samples collected from Spanish carnivores. Detected novel viruses highlight the viral diversity that is present in fecal material of wild carnivores.The authors would like to thank Peter van Run for excellent technical assistance. In addition, the authors wish to thank all the following researchers and institutions for their invaluable help during sampling and for providing the specimens used in this study, specially to Patricia Lizarraga, Ricardo Gutierrez, and Laura Elorza (Martioda Wildlife Rescue Centre-Alava Regional Council), Luis Javier Chueca (UPV-EHU), Asun Gomez (TRAGSATEC), Maddis Podra (European mink Association) and the technical staff and rangers from La Rioja Government and Alava regional council. We would like to thank also La Rioja Government (Agriculture, Livestock and Environmental Council. General Direction of Natural Environment. Nature Conservation and Planning Service) and Alava Regional Council (Department of Environment. Biodiversity Section) for providing the legal permissions required to develop this study. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007 -2013) under the project "European Management Platform for Emerging and Re-emerging Infectious disease Entities" (EMPERIE) EC grant agreement number 223498, the VIRGO Consortium and the Niedersachsen-Research Network on Neuroinfectiology (N-RENNT) of the Ministry of Science and Culture of Lower Saxony. In addition, this research has been partially funded by the Basque Government through the Research group on "Systematics, Biogeography and Population Dynamics" (Ref. IT317-10; GIC10/76). A. Ruiz-Gonzalez holds a Post doc fellowship awarded by the Department of Education, Universities and Research of the Basque Government (Ref. DKR-2012-64) and was awarded by a short visit Research grant from the ConGenOmics Research networking programme of the European Science Foundation (ESF) in order to visit the Department of Viroscience, Erasmus Medical Centre and develop the current research project

    Short-Range Correlations and the One-Body Density Matrix in Finite Nuclei

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    The effects of short-range correlations derived from a realistic meson-exchange potential on the single-particle density matrix in finite nuclei are investigated by analyzing the one-body density in terms of the natural orbits. Basic features of these natural orbits and their spectral distributions are discussed. For many observables it seems to be sufficient to approximate the one-body density matrix in terms of those natural orbits, which exhibit the largest occupation probabilities. For the investigation of the high-momentum components in the single-particle density, however, it is important to take into account natural orbits with small occupation probabilities, originating from the single-particle Green function at large negative energies.Comment: 13 pages, RevTeX, 5 figures adde

    Enantiomerically enriched, polycrystalline molecular sieves

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    Zeolite and zeolite-like molecular sieves are being used in a large number of applications such as adsorption and catalysis. Achievement of the long-standing goal of creating a chiral, polycrystalline molecular sieve with bulk enantioenrichment would enable these materials to perform enantioselective functions. Here, we report the synthesis of enantiomerically enriched samples of a molecular sieve. Enantiopure organic structure directing agents are designed with the assistance of computational methods and used to synthesize enantioenriched, polycrystalline molecular sieve samples of either enantiomer. Computational results correctly predicted which enantiomer is obtained, and enantiomeric enrichment is proven by high-resolution transmission electron microscopy. The enantioenriched and racemic samples of the molecular sieves are tested as adsorbents and heterogeneous catalysts. The enantioenriched molecular sieves show enantioselectivity for the ring opening reaction of epoxides and enantioselective adsorption of 2-butanol (the R enantiomer of the molecular sieve shows opposite and approximately equal enantioselectivity compared with the S enantiomer of the molecular sieve, whereas the racemic sample of the molecular sieve shows no enantioselectivity)

    The Single-Particle Spectral Function of 16O^{16}{\rm O}

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    The influence of short-range correlations on the pp-wave single-particle spectral function in 16O^{16}{\rm O} is studied as a function of energy. This influence, which is represented by the admixture of high-momentum components, is found to be small in the pp-shell quasihole wave functions. It is therefore unlikely that studies of quasihole momentum distributions using the (e,e′p)(e,e'p) reaction will reveal a significant contribution of high momentum components. Instead, high-momentum components become increasingly more dominant at higher excitation energy. The above observations are consistent with the energy distribution of high-momentum components in nuclear matter.Comment: 5 pages, RevTeX, 3 figure

    Imaging the mechanical properties of nanowire arrays

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    Dimensional and contact resonance (CR) images of nanowire (NW) arrays are measured using our new-developed CR imaging (CRI) setup. Then a reference method is employed to calculate the indentation modulus of NWs (Mi,NW) representing the elasticity of NWs, by measuring NW arrays (NWAs) and reference samples at the same static probing force. Furthermore, topography is imaged in combination with CR and Mi,NW separately by software, whereby the relation between both parameters of NWAs is visualized. As typical examples, 3D imaging of topography and Mi,NW is performed with Si pillar, Cu and ZnO NWAs. The novel method allows for fast mechanical performance measurements of large-scale vertically-aligned NW arrays (NWAs) without releasing them from their substrates

    Migraine aura: retracting particle-like waves in weakly susceptible cortex

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    Cortical spreading depression (SD) has been suggested to underlie migraine aura. Despite a precise match in speed, the spatio-temporal patterns of SD and aura symptoms on the cortical surface ordinarily differ in aspects of size and shape. We show that this mismatch is reconciled by utilizing that both pattern types bifurcate from an instability point of generic reaction-diffusion models. To classify these spatio-temporal pattern we suggest a susceptibility scale having the value [sigma]=1 at the instability point. We predict that human cortex is only weakly susceptible to SD ([sigma]&#x3c;1), and support this prediction by directly matching visual aura symptoms with anatomical landmarks using fMRI retinotopic mapping. We discuss the increased dynamical repertoire of cortical tissue close to [sigma]=1, in particular, the resulting implications on migraine pharmacology that is hitherto tested in the regime ([sigma]&#x3e;&#x3e;1), and potentially silent aura occurring below a second bifurcation point at [sigma]=0 on the susceptible scale
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