4,298 research outputs found
Milk, coronary heart disease and mortality
<b>STUDY OBJECTIVE</b> To study the association between reported milk consumption and cardiovascular and all cause mortality.
<b>DESIGN</b> A prospective study of 5765 men aged 35-64 at the time of examination.
<b>SETTING</b> Workplaces in the west of Scotland between 1970 and 1973.
<b>PARTICIPANTS</b> Men who completed a health and lifestyle questionnaire, which asked about daily milk consumption, and who attended for a medical examination.
<b>MAIN RESULTS</b> 150 (2.6%) men reported drinking more than one and a third pints a day, Some 2977 (51.6%) reported drinking between a third and one and a third pints a day and 2638 (45.8%) reported drinking less than a third of a pint a day. There were a total of 2350 deaths over the 25 year follow up period, of which 892 deaths were attributed to coronary heart disease. The relative risk, adjusted for socioeconomic position, health behaviours and health status for deaths from all causes for men who drank one third to one and a third pints a day versus those who drank less than a third of a pint was 0.90 (95% CI 0.83, 0.97). The adjusted relative risk for deaths attributed to coronary heart disease for men who drank one third to one and a third pints a day versus those who drank less than one third of a pint was 0.92 (95% CI 0.81, 1.06).
<b>CONCLUSIONS</b> No evidence was found that men who consumed milk each day, at a time when most milk consumed was full fat milk, were at increased risk of death from all causes or death from coronary heart disease
The supersoft X-ray source in V5116 Sgr I. The high resolution spectra
Classical novae occur on the surface of an accreting white dwarf in a binary
system. After ejection of a fraction of the envelope and when the expanding
shell becomes optically thin to X-rays, a bright source of supersoft X-rays
arises, powered by residual H burning on the surface of the white dwarf. While
the general picture of the nova event is well established, the details and
balance of accretion and ejection processes in classical novae are still full
of unknowns. The long-term balance of accreted matter is of special interest
for massive accreting white dwarfs, which may be promising supernova Ia
progenitor candidates. V5116 Sgr was observed as a bright and variable
supersoft X-ray source by XMM-Newton 610~days after outburst. The light curve
showed a periodicity consistent with the orbital period. During one third of
the orbit the luminosity was a factor of seven brighter than during the other
two thirds of the orbital period. In the present work we aim to disentangle the
X-ray spectral components of V5116 Sgr and their variability. We present the
high resolution spectra obtained with XMM-Newton RGS and Chandra LETGS/HRC-S in
March and August 2007. The grating spectrum during the periods of high-flux
shows a typical hot white dwarf atmosphere dominated by absorption lines of N
VI and N VII. During the low-flux periods, the spectrum is dominated by an
atmosphere with the same temperature as during the high-flux period, but with
several emission features superimposed. Some of the emission lines are well
modeled with an optically thin plasma in collisional equilibrium, rich in C and
N, which also explains some excess in the spectra of the high-flux period. No
velocity shifts are observed in the absorption lines, with an upper limit set
by the spectral resolution of 500 km/s, consistent with the expectation of a
non-expanding atmosphere so late in the evolution of the post-nova.Comment: 12 pages, 15 figures, 4 tables; accepted for publication in Astronomy
and Astrophysic
Substorms on Mercury?
Qualitative similarities between some of the variations in the Mercury encounter data and variations in the corresponding regions of the earth's magnetosphere during substorms are pointed out. The Mariner 10 data on Mercury show a strong interaction between the solar wind and the plant similar to a scaled down version of that for the earth's magnetosphere. Some of the features observed in the night side Mercury magnetosphere suggest time dependent processes occurring there
X-ray and UV observations of nova V598 Puppis between 147 and 255 days after outburst
Aims: The launch of Swift has allowed many more novae to be observed
regularly over the X-ray band. Such X-ray observations of novae can reveal
ejecta shocks and the nuclear burning white dwarf, allowing estimates to be
made of the ejecta velocity. Methods: We analyse XMM-Newton and Swift X-ray and
UV observations of the nova V598 Pup, which was initially discovered in the
XMM-Newton slew survey. These data were obtained between 147 and 255 days after
the nova outburst, and are compared with the earlier, brighter slew detection.
Results: The X-ray spectrum consists of a super-soft source, with the soft
emission becoming hotter and much fainter between days ~147 and ~172 after the
outburst, and a more slowly declining optically thin component, formed by
shocks with kT ~ 200-800 eV (corresponding to velocities of 400-800 km s^-1).
The main super-soft phase had a duration of less than 130 days. The Reflection
Grating Spectrometer data show evidence of emission lines consistent with
optically thin emission of kT ~100 eV and place a limit on the density of the
surrounding medium of log(n_e/cm^-3) < 10.4 at the 90 % level. The UV emission
is variable over short timescales and fades by at least one magnitude (at
lambda ~ 2246-2600 angstrom) between days 169 and 255.Comment: 6 pages, 5 figures, accepted for publication in A&
From X-ray dips to eclipse: Witnessing disk reformation in the recurrent nova USco
The 10th recorded outburst of the recurrent eclipsing nova USco was observed
simultaneously in X-ray, UV, and optical by XMM-Newton on days 22.9 and 34.9
after outburst. Two full passages of the companion in front of the nova ejecta
were observed, witnessing the reformation of the accretion disk. On day 22.9,
we observed smooth eclipses in UV and optical but deep dips in the X-ray light
curve which disappeared by day 34.9, then yielding clean eclipses in all bands.
X-ray dips can be caused by clumpy absorbing material that intersects the line
of sight while moving along highly elliptical trajectories. Cold material from
the companion could explain the absence of dips in UV and optical light. The
disappearance of X-ray dips before day 34.9 implies significant progress in the
formation of the disk. The X-ray spectra contain photospheric continuum
emission plus strong emission lines, but no clear absorption lines. Both
continuum and emission lines in the X-ray spectra indicate a temperature
increase from day 22.9 to day 34.9. We find clear evidence in the spectra and
light curves for Thompson scattering of the photospheric emission from the
white dwarf. Photospheric absorption lines can be smeared out during scattering
in a plasma of fast electrons. We also find spectral signatures of resonant
line scattering that lead to the observation of the strong emission lines.
Their dominance could be a general phenomenon in high-inclination systems such
as Cal87.Comment: Submitted to ApJ. 16 pages, 16 figure
Evolution of X-ray spectra and light curves of V1494 Aquilae
We present six Chandra X-ray spectra and light curves obtained for the nova
V1494 Aql (1999 #2) in outburst. The first three observations were taken with
ACIS-I on days 134, 187, and 248 after outburst. The count rates were 1.00,
0.69 and 0.53 cps, respectively. We found no significant periodicity in the
ACIS light curves. The X-ray spectra show continuum emission and lines
originating from N and O. We found acceptable spectral fits using isothermal
APEC models with significantly increased elemental abundances of O and N for
all observations. On day 248 after outburst a bright soft component appeared in
addition to the fading emission lines. The Chandra observations on days 300,
304, and 727 were carried out with the HRC/LETGS. The spectra consist of
continuum emission plus strong emission lines of O and N, implying a high
abundance of these elements. On day 300, a flare occurred and periodic
oscillations were detected in the light curves taken on days 300 and 304. This
flare must have originated deep in the outflowing material since it was
variable on short time scales. The spectra extracted immediately before and
after the flare are remarkably similar, implying that the flare was an
extremely isolated event. Our attempts to fit blackbody, Cloudy, or APEC models
to the LETG spectra failed, owing to the difficulty in disentangling continuum
and emission line components. The spectrum extracted during the flare shows a
significant increase in the strengths of many of the lines and the appearance
of several previously undetected lines. In addition, some of the lines seen
before and after the flare are not present during the flare. On day 727 only
the count rate from the zeroth order could be derived, and the source was too
faint for the extraction of a light curve or spectrum.Comment: 7 pages, 6 figures, 3 Table
A spatially resolved limb flare on Algol B observed with XMM-Newton
We report XMM-Newton observations of the eclipsing binary Algol A (B8V) and B
(K2III). The XMM-Newton data cover the phase interval 0.35 - 0.58, i.e.,
specifically the time of optical secondary minimum, when the X-ray dark B-type
star occults a major fraction of the X-ray bright K-type star. During the
eclipse a flare was observed with complete light curve coverage. The decay part
of the flare can be well described with an exponential decay law allowing a
rectification of the light curve and a reconstruction of the flaring plasma
region. The flare occurred near the limb of Algol B at a height of about 0.1R
with plasma densities of a few times 10^11 cm^-3 consistent with spectroscopic
density estimates. No eclipse of the quiescent X-ray emission is observed
leading us to the conclusion that the overall coronal filling factor of Algol B
is small.Comment: 8 pages, 7 figures, accepted by A&
Astrophysical Fluids of Novae: High Resolution Pre-decay X-ray spectrum of V4743 Sagittarii
Eight X-ray observations of V4743 Sgr (2002), observed with Chandra and
XMM-Newton are presented. The nova turned off some time between days 301.9 and
371, and the X-ray flux subsequently decreased from day 301.9 to 526 following
an exponential decline time scale of days. We use the absorption
lines present in the SSS spectrum for diagnostic purposes, and characterize the
physics and the dynamics of the expanding atmosphere during the explosion of
the nova. The information extracted from this first stage is then used as input
for computing full photoionization models of the ejecta in V4743 Sgr. The SSS
spectrum is modeled with a simple black-body and multiplicative Gaussian lines,
which provides us of a general kinematical picture of the system, before it
decays to its faint phase (Ness et al. 2003). In the grating spectra taken
between days 180.4 and 370, we can resolve the line profiles of absorption
lines arising from H-like and He-like C, N, and O, including transitions
involving higher principal quantum numbers. Except for a few interstellar
lines, all lines are significantly blue-shifted, yielding velocities between
1000 and 6000 km/s which implies an ongoing mass loss. It is shown that
significant expansion and mass loss occur during this phase of the explosion,
at a rate . Our measurements show that the efficiency of the amount of
energy used for the motion of the ejecta, defined as the ratio between the
kinetic luminosity and the radiated luminosity , is
of the order of one.Comment: 25 pages, 9 figures. Accepted in book: Recent Advances in Fluid
Dynamics with Environmental Applications, pp.365-39
Microscopic mechanisms of dephasing due to electron-electron interactions
We develop a non-perturbative numerical method to study tunneling of a single
electron through an Aharonov-Bohm ring where several strongly interacting
electrons are bound. Inelastic processes and spin-flip scattering are taken
into account. The method is applied to study microscopic mechanisms of
dephasing in a non-trivial model. We show that electron-electron interactions
described by the Hubbard Hamiltonian lead to strong dephasing: the transmission
probability at flux is high even at small interaction strength. In
addition to inelastic scattering, we identify two energy conserving mechanisms
of dephasing: symmetry-changing and spin-flip scattering. The many-electron
state on the ring determines which of these mechanisms will be at play:
transmitted current can occur either in elastic or inelastic channels, with or
without changing the spin of the scattering electron.Comment: 11 pages, 16 figures Submitted to Phys. Rev.
Investigating caffeine levels in water sources in Morehead, Kentucky
https://scholarworks.moreheadstate.edu/student_scholarship_posters/1070/thumbnail.jp
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