5,997 research outputs found
Swift observations of the 2015 outburst of AG Peg -- from slow nova to classical symbiotic outburst
Symbiotic stars often contain white dwarfs with quasi-steady shell burning on
their surfaces. However, in most symbiotics, the origin of this burning is
unclear. In symbiotic slow novae, however, it is linked to a past thermonuclear
runaway. In June 2015, the symbiotic slow nova AG Peg was seen in only its
second optical outburst since 1850. This recent outburst was of much shorter
duration and lower amplitude than the earlier eruption, and it contained
multiple peaks -- like outbursts in classical symbiotic stars such as Z And. We
report Swift X-ray and UV observations of AG Peg made between June 2015 and
January 2016. The X-ray flux was markedly variable on a time scale of days,
particularly during four days near optical maximum, when the X-rays became
bright and soft. This strong X-ray variability continued for another month,
after which the X-rays hardened as the optical flux declined. The UV flux was
high throughout the outburst, consistent with quasi-steady shell burning on the
white dwarf. Given that accretion disks around white dwarfs with shell burning
do not generally produce detectable X-rays (due to Compton-cooling of the
boundary layer), the X-rays probably originated via shocks in the ejecta. As
the X-ray photo-electric absorption did not vary significantly, the X-ray
variability may directly link to the properties of the shocked material. AG
Peg's transition from a slow symbiotic nova (which drove the 1850 outburst) to
a classical symbiotic star suggests that shell burning in at least some
symbiotic stars is residual burning from prior novae.Comment: Accepted by MNRAS 23 June 2016. Manuscript submitted in original form
5 April 201
Spherical harmonic decomposition applied to spatial-temporal analysis of human high-density EEG
We demonstrate an application of spherical harmonic decomposition to analysis
of the human electroencephalogram (EEG). We implement two methods and discuss
issues specific to analysis of hemispherical, irregularly sampled data.
Performance of the methods and spatial sampling requirements are quantified
using simulated data. The analysis is applied to experimental EEG data,
confirming earlier reports of an approximate frequency-wavenumber relationship
in some bands.Comment: 12 pages, 8 figures, submitted to Phys. Rev. E, uses APS RevTeX
style
Hypertension and sudden death disparate effects of calcium entry blocker and diuretic therapy on cardiac dysrhythmias
This study was designed to evaluate the impact of antihypertensive therapy on cardiac dysrhythmias in 13 hypertensive patients who received calcium entry blockers and in 10 hypertensive patients who received hydrochlorothiazide. Mean arterial pressure fell to a similar extent in both treatment groups; however, left ventricular mass index decreased (from 102±4 to 95±2 g/m2) only in patients receiving calcium entry blockers, but not in those taking hydrochlorothiazide. The prevalence of premature ventricular contractions decreased 74% from 21 14/h to 5.7 ± 6/h in the calcium entry blocker group, but did not change in the hydrochlorothiazide group (15± 17/h to 16± 13/h). Couplets, multiform contractions, ventricular tachycardia, and supraventricular tachycardia were completely abolished after calcium entry blocker therapy, whereas the prevalence of these arrhythmias remained unchanged during treatment with hydrochlorothiazide. We conclude that antihypertensive therapy with calcium entry blockers (but not with thiazide diuretics) reduces left ventricular mass and the prevalence and severity of ventricular dysrhythmias. Whether this reduction will improve the ominous prognosis of left ventricular hypertrophy and diminish the risk of sudden death remains unknown
Sea bass (Dicentrarchus labrax L.) vitellogenin : 2. Validation of an enzyme-linked immunosorbent assay (ELISA)
Prevalencia de factores de riesgo cardiovascular clásicos en población adulta de Talca, Chile, 2005
Departamento de BioquĂmica ClĂnica e InmunohematologĂa, Facultad de Ciencias de la Salud, Universidad de Talca, Talca, Chile.
Instituto de Matemática y FĂsica, Universidad de Talca, Talca, Chile.
Departamento de Salud PĂşblica, Facultad de Ciencias de la Salud, Universidad de Talca, Talca, Chile. Escuela
de PsicologĂa, Universidad de Talca, Talca, Chile.Background: Cardiovascular disease (CVD) has several traditional risk factors (RF), and some of them are potentially modifiable. Aim: To determine the prevalence of most common risk factors in adult population in Talca in Central Chile. Subjects and methods: We studied 1007 subjects aged 18 to 74 years (66% women), living in Talca, selected by a probability sampling. They answered a questionnaire and anthropometry, blood pressure, lipid profile and blood glucose were measured. Results: Thirty seven percent of subjects smoked, 70.1% had a body mass index over 25 kg/m2 and 41% had an abnormally high circumference. High blood pressure was found in 37% (36% of these subjects were unaware of this condition), 44.5% had hypercholesterolemia, 21.5% had low HDL cholesterol, 40.1% had hypertriglyceridemia and 26.3% had high blood glucose levels. Conclusions: There is a high prevalence of risk factors for CVD in adult population from Talca. The prevalence of risk factors is higher than that reported by the 2003 National Health Survery
On the Stability of Non-Extremal Conifold Backgrounds with Sources
We present finite temperature solutions describing N_c D5 branes wrapped on
the S^2 of the resolved conifold in the presence of N_f flavor brane sources
and their backreaction, i.e. N_f/N_c ~ 1. In these solutions the dilaton does
not blow up at infinity but stabilizes to a finite value. Thus, we can use them
to generate new ones with D5 and D3 charge. The resulting backgrounds are
non-extremal versions of the "flavored" resolved deformed conifold. It is
tempting to interpret these solutions as gravity duals of finite temperature
field theories exhibiting non-trivial phenomena as Seiberg dualities, Higgsing
and confinement. However, a first necessary step in this direction is to
investigate their stability. We study the specific heat of these new flavored
backgrounds and find that they are thermodynamically unstable. Our results on
the stability also apply to some of the non-extremal backgrounds with
Klebanov-Strassler asymptotics found in the literature.Comment: 34+16 pages, 26 figures. Published versio
Predictive Power of Strong Coupling in Theories with Large Distance Modified Gravity
We consider theories that modify gravity at cosmological distances, and show
that any such theory must exhibit a strong coupling phenomenon, or else it is
either inconsistent or is already ruled out by the solar system observations.
We show that all the ghost-free theories that modify dynamics of spin-2
graviton on asymptotically flat backgrounds, automatically have this property.
Due to the strong coupling effect, modification of the gravitational force is
source-dependent, and for lighter sources sets in at shorter distances. This
universal feature makes modified gravity theories predictive and potentially
testable not only by cosmological observations, but also by precision
gravitational measurements at scales much shorter than the current cosmological
horizon. We give a simple parametrization of consistent large distance modified
gravity theories and their predicted deviations from the Einsteinian metric
near the gravitating sources.Comment: 12 pages, Latex, to be published in New Journal of Physic
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