549 research outputs found
The effects of the spontaneous presence of a spouse/partner and others on cardiovascular reactions to an acute psychological challenge
The presence of supportive others has been associated with attenuated cardiovascular reactivity in the laboratory. The effects of the presence of a spouse and others in a more naturalistic setting have received little attention. Blood pressure and heart rate reactions to mental stress were recorded at home in 1028 married/partnered individuals. For 112 participants, their spouse/partner was present; for 78, at least one other person was present. Women tested with a spouse/partner present showed lower magnitude systolic blood pressure and heart rate reactivity than those tested without. Individuals tested with at least one nonspousal other present also displayed attenuated reactivity. This extends the results of laboratory studies and indicates that the spontaneous presence of others is associated with a reduction in cardiovascular reactivity in an everyday environment; spouse/partner presence would appear to be especially effective for women.\ud
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Herschel/HIFI Spectral Mapping of C, CH, and CH in Orion BN/KL: The Prevailing Role of Ultraviolet Irradiation in CH Formation
The CH ion is a key species in the initial steps of interstellar carbon
chemistry. Its formation in diverse environments where it is observed is not
well understood, however, because the main production pathway is so endothermic
(4280 K) that it is unlikely to proceed at the typical temperatures of
molecular clouds. We investigation CH formation with the first
velocity-resolved spectral mapping of the CH rotational
transitions, three sets of CH -doubled triplet lines, C and
C, and CHOH 835~GHz E-symmetry Q branch transitions, obtained
with Herschel/HIFI over 12 arcmin centered on the Orion BN/KL
source. We present the spatial morphologies and kinematics, cloud boundary
conditions, excitation temperatures, column densities, and C optical
depths. Emission from C, CH, and CH is indicated to arise in the
diluted gas, outside of the explosive, dense BN/KL outflow. Our models show
that UV-irradiation provides favorable conditions for steady-state production
of CH in this environment. Surprisingly, no spatial or kinematic
correspondences of these species are found with H S(1) emission tracing
shocked gas in the outflow. We propose that C is being consumed by rapid
production of CO to explain the lack of C and CH in the outflow, and
that fluorescence provides the reservoir of H excited to higher
ro-vibrational and rotational levels. Hence, in star-forming environments
containing sources of shocks and strong UV radiation, a description of CH
formation and excitation conditions is incomplete without including the
important --- possibly dominant --- role of UV irradiation.Comment: Accepted for publication in The Astrophysical Journa
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Franz Volhard lecture: should doctors still measure blood pressure? The missing patients with masked hypertension
The traditional reliance on blood pressure (BP) measurement in the medical setting misses a significant number of individuals with masked hypertension, who have normal clinic BP but persistently high daytime BP when measured out of the office. We suggest that masked hypertension may be a precursor of clinically recognized sustained hypertension and is associated with increased cardiovascular risk compared with consistent normotension. We discuss factors that may contribute to clinic–daytime BP differences as well as the changing relationship between these two measures over time. Anxiety at the time of BP measurement and having been diagnosed as hypertensive appear to be two possible mechanisms. The identification of individuals with masked hypertension is of great clinical importance and requires out-of-office BP screening. Ambulatory BP monitoring is the best established technique for doing this, but home monitoring may be applicable in the future
LEDA 074886: A remarkable rectangular-looking galaxy
We report the discovery of an interesting and rare, rectangular-shaped
galaxy. At a distance of 21 Mpc, the dwarf galaxy LEDA 074886 has an absolute
R-band magnitude of -17.3 mag. Adding to this galaxy's intrigue is the presence
of an embedded, edge-on stellar disk (of extent 2R_{e,disk} = 12 arcsec = 1.2
kpc) for which Forbes et al. reported V_rot/sigma ~ 1.4. We speculate that this
galaxy may be the remnant of two (nearly edge-one) merged disk galaxies in
which the initial gas was driven inward and subsequently formed the inner disk,
while the stars at larger radii effectively experienced a dissipationless
merger event resulting in this `emerald cut galaxy' having very boxy isophotes
with a_4/a = -0.05 to -0.08 from 3 to 5 kpc. This galaxy suggests that
knowledge from simulations of both `wet' and `dry' galaxy mergers may need to
be combined to properly understand the various paths that galaxy evolution can
take, with a particular relevance to blue elliptical galaxies.Comment: To appear in ApJ. Six pages including references and figure
Evolutionary Status of Dwarf ``Transition'' Galaxies
We present deep B, R and Halpha imaging of 3 dwarf galaxies: NGC3377A,
NGC4286, and IC3475. Based on previous broadband imaging and HI studies, these
mixed-morphology galaxies were proposed by Sandage & Hoffman (1991) to be,
respectively, a gas-rich low surface brightness Im dwarf, a nucleated dwarf
that has lost most of its gas and is in transition from Im to dS0,N, and the
prototypical example of a gas-poor ``huge low surface brightness'' early-type
galaxy. From the combination of our broadband and Halpha imaging with the
published information on the neutral gas content of these three galaxies, we
find that (1) NGC3377A is a dwarf spiral; (2) NGC3377A and NGC4286 have
comparable amounts of ongoing star formation, as indicated by their Halpha
emission, while IC3475 has no detected HII regions to a very low limit; (3) the
global star formation rates are at least a factor of 20 below that of 30
Doradus for NGC3377A and NGC4286; (4) while the amount of star formation is
comparable, the distribution of star forming regions is very different between
NGC3377A and NGC4286; (5) given their current star formation rates and gas
contents, both NGC3377A and NGC4286 can continue to form stars for more than a
Hubble time; (6) both NGC3377A and NGC4286 have integrated total B-R colors
that are redder than the integrated total B-R color for IC3475, and thus it is
unlikely that either galaxy will ever evolve into an IC3475 counterpart; and
(7) IC3475 is too blue to be a dE. We thus conclude that we have not identified
potential precursors to galaxies such as IC3475, and unless signifcant changes
occur in the star formation rates, neither NGC3377A nor NGC4286 will evolve
into a dwarf elliptical or dwarf spheroidal within a Hubble time.Comment: 34 pages, 6 jpg figures, 3 postscript figures, and 4 tables, uses
AASTeX, ApJ, in pres
An Imaging Survey of Early-Type Barred Galaxies
This paper presents the results of a high-resolution imaging survey, using
both ground-based and Hubble Space Telescope images, of a complete sample of
nearby barred S0--Sa galaxies in the field, with a particular emphasis on
identifying and measuring central structures within the bars: secondary bars,
inner disks, nuclear rings and spirals, and off-plane dust. A discussion of the
frequency and statistical properties of the various types of inner structures
has already been published. Here, we present the data for the individual
galaxies and measurements of their bars and inner structures. We set out the
methods we use to find and measure these structures, and how we discriminate
between them. In particular, we discuss some of the deficiencies of ellipse
fitting of the isophotes, which by itself cannot always distinguish between
bars, rings, spirals, and dust, and which can produce erroneous measurements of
bar sizes and orientations.Comment: LaTeX, 66 pages (including 42 figures, 36 in color). To appear in The
Astrophysical Journal Supplement. Full-resolution and text-only versions
available at http://www.iac.es/galeria/erwin/research
Detection of Compact Nuclear X-Ray Emission in NGC 4736
We report the results from a deep ROSAT PSPC observation of LINER galaxy NGC
4736. Two bright sources are detected, separated by only about 1', with the
brighter one coinciding with the center of the galaxy. Neither source shows
apparent X-ray variability on time-scales of minutes to hours in the ROSAT
band. Simple power-law models, typical of AGN X-ray spectra, produce poor fits
to the observed X-ray spectrum of the nuclear source. The addition of a
Raymond-Smith component improves the fits significantly. This is consistent
with the presence of hot gas in the nuclear region with kT=~0.3 keV, in
addition to a compact nuclear source. However, a careful examination of the
residuals reveal apparent features at low energies (< 0.25 keV). We find that
the addition of a narrow emission line at about 0.22 keV is a significant
improvement to the parameterization of the spectrum. We examine the results in
the light of the accuracy of the PSPC spectral calibration. The derived photon
index is about 2.3, which is similar to those for Seyfert 1 galaxies measured
in the ROSAT energy range. On the other hand, the 0.1-2 keV luminosity for the
compact source is only about 3.4x10^{39} erg/s, much fainter than typical
Seyfert galaxies. We discuss the implications of these results on the
connection between LINERs and AGNs.
The off-center source is transient in nature. It has a hard X-ray spectrum,
with a photon index of about 1.5, so is likely to be an X-ray binary. There is
still some ambiguity regarding its association with the galaxy. If it is indeed
located in the galaxy, the 0.1-2 keV luminosity would be greater than
5.1x10^{38} erg/s, making it a stellar-mass black hole candidate.Comment: 15 pages, LaTeX (aaspp4.sty), macro rotate.tex, 10 postscript figures
(including 3 color prints) and rotate.tex available at
ftp://space.mit.edu/pub/cui/ngc4736/ . Accepted for publication in Ap
The Frequency of Barred Spiral Galaxies in the Near-IR
We have determined the fraction of barred galaxies in the H-band for a
statistically well-defined sample of 186 spirals drawn from the Ohio State
University Bright Spiral Galaxy survey. We find 56% of our sample to be
strongly barred at H, while another 16% is weakly barred. Only 27% of our
sample is unbarred in the near-infrared. The RC3 and the Carnegie Atlas of
Galaxies both classify only about 30% of our sample as strongly barred. Thus
strong bars are nearly twice as prevalent in the near-infrared as in the
optical. The frequency of genuine optically hidden bars is significant, but
lower than many claims in the literature: 40% of the galaxies in our sample
that are classified as unbarred in the RC3 show evidence for a bar in the
H-band, while for the Carnegie Atlas this fraction is 66%. Our data reveal no
significant trend in bar fraction as a function of morphology in either the
optical or H-band. Optical surveys of high redshift galaxies may be strongly
biased against finding bars, as bars are increasingly difficult to detect at
bluer rest wavelengths.Comment: LaTeX with AASTeX style file, 23 pages with 6 figures. Accepted for
publication in The Astronomical Journal (Feb. 2000
H-alpha Kinematics of the SINGS Nearby Galaxies Survey. II
This is the second part of an H-alpha kinematics follow-up survey of the
Spitzer Infrared Nearby Galaxies Survey (SINGS) sample. The aim of this program
is to shed new light on the role of baryons and their kinematics and on the
dark/luminous matter relation in the star forming regions of galaxies, in
relation with studies at other wavelengths. The data for 37 galaxies are
presented. The observations were made using Fabry-Perot interferometry with the
photon-counting camera FaNTOmM on 4 different telescopes, namely the
Canada-France-Hawaii 3.6m, the ESO La Silla 3.6m, the William Herschel 4.2m,
and the Observatoire du mont Megantic 1.6m telescopes. The velocity fields are
computed using custom IDL routines designed for an optimal use of the data. The
kinematical parameters and rotation curves are derived using the GIPSY
software. It is shown that non-circular motions associated with galactic bars
affect the kinematical parameters fitting and the velocity gradient of the
rotation curves. This leads to incorrect determinations of the baryonic and
dark matter distributions in the mass models derived from those rotation
curves.Comment: 18 pages, 5 figures, 4 tables. Accepted for publication in MNRAS. All
high-res. figures are available at
http://www.astro.umontreal.ca/fantomm/singsII
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