671 research outputs found
Natural Cycles, Gases
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
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
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
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.
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
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
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
The induced pseudoscalar coupling 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 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
, the experimental studies of , 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
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
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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