1,634 research outputs found

    Project NEO Specific Impulse Testing Solutions

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    The Neo test stand is currently configured to fire a horizontally mounted rocket motor with up to 6500 lbf thrust. Currently, the Neo test stand can measure flow of liquid propellant and oxidizer, pressures residing in the closed system up to the combustion chamber. The current configuration does not have the ability to provide all data needed to compute specific impulse. This presents three methods to outfit the NEO test fixture with instrumentation allowing for calculation of specific impulse

    1.65 micrometers (H-band) surface photometry of galaxies. III: observations of 558 galaxies with the TIRGO 1.5m telescope

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    We present near-infrared H-band (1.65 micron) surface photometry of 558 galaxies in the Coma Supercluster and in the Virgo cluster. This data set, obtained with the Arcetri NICMOS3 camera ARNICA mounted on the Gornergrat Infrared Telescope, is aimed at complementing, with observations of mostly early-type objects, our NIR survey of spiral galaxies in these regions, presented in previous papers of this series. Magnitudes at the optical radius, total magnitudes, isophotal radii and light concentration indices are derived. We confirm the existence of a positive correlation between the near-infrared concentration index and the galaxy H-band luminosity. (Tables 1 and 2 are only available in electronic form upon request to [email protected])Comment: 12 pages, 6 figures. Accepted for publication in A&A

    High spectral resolution imaging of the dynamical atmosphere of the red supergiant Antares in the CO first overtone lines with VLTI/AMBER

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    We present high spectral resolution aperture-synthesis imaging of the red supergiant Antares (alpha Sco) in individual CO first overtone lines with VLTI/AMBER. The reconstructed images reveal that the star appears differently in the blue wing, line center, and red wing and shows an asymmetrically extended component. The appearance of the star within the CO lines changes drastically within one year, implying a significant change in the velocity field in the atmosphere. Our modeling suggests an outer atmosphere (MOLsphere) extending to 1.2--1.4 stellar radii with CO column densities of (0.5--1)x10^{20} cm^{-2} and a temperature of ~2000 K. While the velocity field in 2009 is characterized by strong upwelling motions at 20--30 km/s, it changed to strong downdrafts in 2010. On the other hand, the AMBER data in the continuum show only a slight deviation from limb-darkened disks and only marginal time variations. We derive a limb-darkened disk diameter of 37.38+/-0.06 mas and a power-law-type limb-darkening parameter of (8.7+/-1.6)x10^{-2} (2009) and 37.31+/-0.09 mas and (1.5+/-0.2)x10^{-1} (2010). We also obtain Teff = 3660+/-120 K and log L/Lsun = 4.88+/-0.23, which suggests a mass of 15+/-5 Msun with an age of 11-15 Myr. This age is consistent with the recently estimated age for the Upper Scorpius OB association. The properties of the outer atmosphere of Antares are similar to those of another well-studied red supergiant, Betelgeuse. The density of the extended outer atmosphere of Antares and Betelgeuse is higher than predicted by the current 3-D convection simulations by at least six orders of magnitude, implying that convection alone cannot explain the formation of the extended outer atmosphere.Comment: 18 pages, 16 figures, accepted for publication in Astronomy and Astrophysics, short discussion on the age of Antares and the Upper Scorpius OB association added, movies of the reconstructed images available at http://www.mpifr-bonn.mpg.de/staff/kohnaka

    Single-incision laparoscopic adnexectomy in an obese patient with previous laparotomies

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    No case of single-incision laparoscopic surgery in obese patients who had previously undergone multiple midline vertical laparotomies has been described in the literature to date. Hence we report the first case of single-port laparoscopic salpingo-oophorectomy in an obese patient who was affected by a left adnexal mass and who had previously undergone 3 midline vertical laparotomies

    Actividad de investigación científica con alumnos de nivel medio : un estudio de caso

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    El trabajo presenta una actividad de investigación científica sobre el tema Cama de Faquir, realizada con alumnos de nivel medio (15 y 17 años) de una escuela estatal, y desarrollado en partes entre la universidad y la escuela. Los alumnos proyectaron la cama de faquir, la construyeron, y estudiaron la presión que un globo soporta sobre ella sin explotar. Participaron activamente en el proceso de aprendizaje y se familiarizaron con la investigación científica. Cambiaron sus concepciones inicial simplista por una más próxima a la realidad sobre la naturaleza de la investigación y empezaron a utilizar con más frecuencia términos científicos. El hecho de que el trabajo fuera en su mayoría desarrollado en el ambiente universitario, ayudó a los alumnos a desmitificar la universidad, proporcionándoles nuevas perspectivas en sus vidas profesionales

    Near-infrared observations of galaxies in Pisces-Perseus: I. H-band surface photometry of 174 spirals

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    We present near-infrared, H-band (1.65 um), surface photometry of 174 spiral galaxies in the area of the Pisces-Perseus supercluster. The images, acquired with the ARNICA camera mounted on various telescopes, are used to derive radial profiles of surface brightness, ellipticities, and position angles, together with global parameters such as H-band magnitudes and diameters. The mean relation between H-band isophotal diameter D_{21.5} and the B-band D_{25} implies a B-H color of the outer disk bluer than 3.5; moreover, D_{21.5}/D_{25} depends on (global) color and absolute luminosity. The correlations among the various photometric parameters suggest a ratio between isophotal radius D_{21.5}/2 and disk scale length of about 3.5 and a mean disk central brightness of 17.5 H-mag arcsec^{-2}. We confirm the trend of the concentration index C_{31} with absolute luminosity and, to a lesser degree, with morphological type. We also assess the influence of non-axisymmetric structures on the radial profiles and on the derived parameters.Comment: 10 pages, 11 postscript figures (one table and one figure are available only at the CDS); to be published on A&A

    A prática avaliativa de professores de química do ensino médio: um estudo em escolas de comunidades da rede pública estadual de Teresina,

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    O presente trabalho teve como objetivo analisar a concepção de avaliação que permeiam os instrumentos avaliativos utilizados pelos professores de Química do Ensino Médio em comunidades de Teresina. A coleta de dados foi efetuada por meio de questionários aplicados a 20 professores de Química; de observação sistemática e de análise documental de instrumentos avaliativos. Os resultados mostraram que houve predomínio da prova escrita como principal instrumento e que os aspectos quantitativos preponderam sobre os qualitativos na atribuição de nota e os instrumentos de seminários, debates e dinâmicas também são utilizados. Contudo, a concepção de avaliação da grande maioria dos professores não está voltada para a busca de competências e habilidades em seu corpo discente

    Dynamical Mass Estimates of Large-Scale Filaments in Redshift Surveys

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    We propose a new method to measure the mass of large-scale filaments in galaxy redshift surveys. The method is based on the fact that the mass per unit length of isothermal filaments depends only on their transverse velocity dispersion. Filaments that lie perpendicular to the line of sight may therefore have their mass per unit length measured from their thickness in redshift space. We present preliminary tests of the method and find that it predicts the mass per unit length of filaments in an N-body simulation to an accuracy of ~35%. Applying the method to a select region of the Perseus-Pisces supercluster yields a mass-to-light ratio M/L_B around 460h in solar units to within a factor of two. The method measures the mass-to-light ratio on length scales of up to 50h^(-1) Mpc and could thereby yield new information on the behavior of the dark matter on mass scales well beyond that of clusters of galaxies.Comment: 21 pages, LaTeX with 6 figures included. Submitted to Ap

    Transcribed ultraconserved noncoding RNAs (T-UCR) are involved in Barrett's esophagus carcinogenesis.

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    Barretts esophagus (BE) involves a metaplastic replacement of native esophageal squamous epithelium (Sq) by columnar-intestinalized mucosa, and it is the main risk factor for Barrett-related adenocarcinoma (BAc). Ultra-conserved regions (UCRs) are a class non-coding sequences that are conserved in humans, mice and rats. More than 90% of UCRs are transcribed (T-UCRs) in normal tissues, and are altered at transcriptional level in tumorigenesis. To identify the T-UCR profiles that are dysregulated in Barretts mucosa transformation, microarray analysis was performed on a discovery set of 51 macro-dissected samples obtained from 14 long-segment BE patients. Results were validated in an independent series of esophageal biopsy/surgery specimens and in two murine models of Barretts esophagus (i.e. esophagogastric-duodenal anastomosis). Progression from normal to BE to adenocarcinoma was each associated with specific and mutually exclusive T-UCR signatures that included up-regulation of uc.58-, uc.202-, uc.207-, and uc.223- and down-regulation of uc.214+. A 9 T-UCR signature characterized BE versus Sq (with the down-regulation of uc.161-, uc.165-, and uc.327-, and the up-regulation of uc.153-, uc.158-, uc.206-, uc.274-, uc.472-, and uc.473-). Analogous BE-specific T-UCR profiles were shared by human and murine lesions. This study is the first demonstration of a role for T-UCRs in the transformation of Barretts mucosa
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