671 research outputs found

    Natural Cycles, Gases

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    The major gaseous components of the exhaust of stratospheric aircraft are expected to be the products of combustion (CO2 and H2O), odd nitrogen (NO, NO2 HNO3), and products indicating combustion inefficiencies (CO and total unburned hydrocarbons). The species distributions are produced by a balance of photochemical and transport processes. A necessary element in evaluating the impact of aircraft exhaust on the lower stratospheric composition is to place the aircraft emissions in perspective within the natural cycles of stratospheric species. Following are a description of mass transport in the lower stratosphere and a discussion of the natural behavior of the major gaseous components of the stratospheric aircraft exhaust

    UIT Detection of Hot Stars in the Globular Cluster NGC362

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    We used the Ultraviolet Imaging Telescope during the March 1995 Astro-2 mission to obtain a deep far-UV image of the globular cluster NGC 362, which was formerly thought to have an almost entirely red horizontal branch (HB). 84 hot (T_eff > 8500 K) stars were detected within a radius of 8'.25 of the cluster center. Of these, 43 have FUV magnitudes consistent with HB stars in NGC 362, and at least 34 are cluster members. The number of cluster members is made uncertain by background contamination from blue stars in the Small Magellanic Cloud (SMC). There are six candidate supra-HB stars which have probably evolved from the HB. We discuss the implications of these results for the production of hot blue stars in stellar populations.Comment: 10 pages AASLaTeX including one postscript figure and one compressed bitmap, .jpg format. To appear in Ap. J. Letters. Postscript version also available at http://www.astro.virginia.edu/~bd4r

    The Variable Stars of the Draco Dwarf Spheroidal Galaxy - Revisited

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    We present a CCD survey of variable stars in the Draco dwarf spheroidal galaxy. This survey, which has the largest areal coverage since the original variable star survey by Baade & Swope, includes photometry for 270 RR Lyrae stars, 9 anomalous Cepheids, 2 eclipsing binaries, and 12 slow, irregular red variables, as well as 30 background QSOs. Twenty-six probable double-mode RR Lyrae stars were identified. Observed parameters, including mean V and I magnitudes, V amplitudes, and periods, have been derived. Photometric metallicities of the ab-type RR Lyrae stars were calculated according to the method of Jurcsik & Kovacs, yielding a mean metallicity of = -2.19 +/- 0.03. The well known Oosterhoff intermediate nature of the RR Lyrae stars in Draco is reconfirmed, although the double-mode RR Lyrae stars with one exception have properties similar to those found in Oosterhoff type II globular clusters. The period-luminosity relation of the anomalous Cepheids is rediscussed with the addition of the new Draco anomalous Cepheids.Comment: Accepted to AJ. 61 pages, 14 figures, 10 table

    GMRT HI observations of the Eridanus group of galaxies

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    The GMRT HI 21cm-line observations of galaxies in the Eridanus group are presented. The Eridanus group, at a distance of ~23 Mpc, is a loose group of \~200 galaxies. The group extends more than 10 Mpc in projection. The velocity dispersion of the galaxies in the group is ~240 km/s. The galaxies are clustered into different sub-groups. The overall population mix of the group is 30% (E+S0) and 70% (Sp+Irr). The observations of 57 Eridanus galaxies were carried out with the GMRT for ~200 hour. HI emission was detected from 31 galaxies. The channel rms of ~1.0 mJy beam^{-1} was achieved for most of the image-cubes made with 4 hour of data. The corresponding HI column density sensitivity (3-sigma) is ~1x10^{20} cm^{-2} for a velocity-width of ~13.4 km/s. The 3-sigma detection limit of HI mass is ~1.2x10^{7} M_sun for a line-width of 50 km/s. Total HI images, HI velocity fields, global HI line profiles, HI mass surface densities, HI disk parameters and HI rotation curves are presented. The velocity fields are analysed separately for the approaching and the receding sides of the galaxies. This data will be used to study the HI and the radio continuum properties, the Tully-Fisher relations, the dark matter halos, and the kinematical and HI lopsidedness in galaxies.Comment: 75 pages including HI atlas; Accepted for publication in Journal of Astroph. & Astron. March, 200

    Validity of the Manchester Triage System in emergency care: A prospective observational study.

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    OBJECTIVES: To determine the validity of the Manchester Triage System (MTS) in emergency care for the general population of patients attending the emergency department, for children and elderly, and for commonly used MTS flowcharts and discriminators across three different emergency care settings. METHODS: This was a prospective observational study in three European emergency departments. All consecutive patients attending the emergency department during a 1-year study period (2010-2012) were included. Validity of the MTS was assessed by comparing MTS urgency as determined by triage nurses with patient urgency according to a predefined 3-category reference standard as proxy for true patient urgency. RESULTS: 288,663 patients were included in the analysis. Sensitivity of the MTS in the three hospitals ranged from 0.47 (95%CI 0.44-0.49) to 0.87 (95%CI 0.85-0.90), and specificity from 0.84 (95%CI 0.84-0.84) to 0.94 (95%CI 0.94-0.94) for the triage of adult patients. In children, sensitivity ranged from 0.65 (95%CI 0.61-0.70) to 0.83 (95%CI 0.79-0.87), and specificity from 0.83 (95%CI 0.82-0.83) to 0.89 (95%CI 0.88-0.90). The diagnostic odds ratio ranged from 13.5 (95%CI 12.1-15.0) to 35.3 (95%CI 28.4-43.9) in adults and from 9.8 (95%CI 6.7-14.5) to 23.8 (95%CI 17.7-32.0) in children, and was lowest in the youngest patients in 2 out of 3 settings and in the oldest patients in all settings. Performance varied considerably between the different emergency departments. CONCLUSIONS: Validity of the MTS in emergency care is moderate to good, with lowest performance in the young and elderly patients. Future studies on the validity of triage systems should be restricted to large, multicenter studies to define modifications and improve generalizability of the findings.info:eu-repo/semantics/publishedVersio

    The Hubble Space Telescope Key Project on the Extragalactic Distance Scale XXIV: The Calibration of Tully-Fisher Relations and the Value of the Hubble Constant

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    This paper presents the calibration of BVRIH$ Tully-Fisher relations based on Cepheid distances to 21 galaxies within 25 Mpc, and 23 clusters within 10,000 km/s. These relations have been applied to several distant cluster surveys in order to derive a value for the Hubble constant, H0, mainly concentrating on an I-band all-sky survey by Giovanelli and collaborators which consisted of total I magnitudes and 50% linewidth data for ~550 galaxies in 16 clusters. For comparison, we also derive the values of H0 using surveys in B-band and V-band by Bothun and collaborators, and in H-band by Aaronson and collaborators. Careful comparisons with various other databases from literature suggest that the H-band data, whose magnitudes are isophotal magnitudes extrapolated from aperture magnitudes rather than total magnitudes, are subject to systematic uncertainties. Taking a weighted average of the estimates of Hubble constants from four surveys, we obtain H0 = 71 +- 4 (random) +- 7 (systematic) km/s/Mpc. We have also investigated how various systematic uncertainties affect the value of H0 such as the internal extinction correction method used, Tully-Fisher slopes and shapes, a possible metallicity dependence of the Cepheid period-luminosity relation and cluster population incompleteness bias.Comment: 34 pages, 13 figure

    Нарушение межличностных отношений супругов при отдаленных последствиях закрытой черепно−мозговой травмы у мужа

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    Методами психодиагностического исследования выявлены закономерности нарушения межличностной адаптации супругов при отдаленных последствиях военной закрытой черепно−мозговой травмы у мужа.The methods of psychodiagnosis were used to reveal the regularities of interpersonal adaptation disorders in spouses at long−term sequelae of military closed brain injury in the husband

    Induced pseudoscalar coupling of the proton weak interaction

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    The induced pseudoscalar coupling gpg_p is the least well known of the weak coupling constants of the proton's charged--current interaction. Its size is dictated by chiral symmetry arguments, and its measurement represents an important test of quantum chromodynamics at low energies. During the past decade a large body of new data relevant to the coupling gpg_p has been accumulated. This data includes measurements of radiative and non radiative muon capture on targets ranging from hydrogen and few--nucleon systems to complex nuclei. Herein the authors review the theoretical underpinnings of gpg_p, the experimental studies of gpg_p, and the procedures and uncertainties in extracting the coupling from data. Current puzzles are highlighted and future opportunities are discussed.Comment: 58 pages, Latex, Revtex4, prepared for Reviews of Modern Physic

    Analyzing the Impacts of Dams on Riparian Ecosystems: A Review of Research Strategies and Their Relevance to the Snake River Through Hells Canyon

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    River damming provides a dominant human impact on river environments worldwide, and while local impacts of reservoir flooding are immediate, subsequent ecological impacts downstream can be extensive. In this article, we assess seven research strategies for analyzing the impacts of dams and river flow regulation on riparian ecosystems. These include spatial comparisons of (1) upstream versus downstream reaches, (2) progressive downstream patterns, or (3) the dammed river versus an adjacent free-flowing or differently regulated river(s). Temporal comparisons consider (4) pre- versus post-dam, or (5) sequential post-dam conditions. However, spatial comparisons are complicated by the fact that dams are not randomly located, and temporal comparisons are commonly limited by sparse historic information. As a result, comparative approaches are often correlative and vulnerable to confounding factors. To complement these analyses, (6) flow or sediment modifications can be implemented to test causal associations. Finally, (7) process-based modeling represents a predictive approach incorporating hydrogeomorphic processes and their biological consequences. In a case study of Hells Canyon, the upstream versus downstream comparison is confounded by a dramatic geomorphic transition. Comparison of the multiple reaches below the dams should be useful, and the comparison of Snake River with the adjacent free-flowing Salmon River may provide the strongest spatial comparison. A pre- versus post-dam comparison would provide the most direct study approach, but pre-dam information is limited to historic reports and archival photographs. We conclude that multiple study approaches are essential to provide confident interpretations of ecological impacts downstream from dams, and propose a comprehensive study for Hells Canyon that integrates multiple research strategies

    HST Observations of New Horizontal Branch Structures in the Globular Cluster omega Centauri

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    The globular cluster omega Centauri contains the largest known population of very hot horizontal branch (HB) stars. We have used the Hubble Space Telescope to obtain a far-UV/optical color-magnitude diagram of three fields in omega Cen. We find that over 30% of the HB objects are ``extreme'' HB or hot post-HB stars. The hot HB stars are not concentrated toward the cluster center, which argues against a dynamical origin for them. A wide gap in the color distribution of the hot HB stars appears to correspond to gaps found earlier in several other clusters. This suggests a common mechanism, probably related to giant branch mass loss. The diagram contains a significant population of hot sub-HB stars, which we interpret as the ``blue-hook'' objects predicted by D'Cruz et al. (1996a). These are produced by late He-flashes in stars which have undergone unusually large giant branch mass loss. omega Cen has a well-known spread of metal abundance, and our observations are consistent with a giant branch mass loss efficiency which increases with metallicity.Comment: Submitted to ApJ, 12 pages, including 3 figures, also available at http://www.physics.usyd.edu.au/~noella/research.htm
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