119 research outputs found
Limit on Continuous Neutrino Emission from Neutron Stars
The timing data of the binary pulsar PSR1913+16, are used to establish an
upper limit on the rate of continuous neutrino emission from neutron stars.
Neutrino emission from each of the neutron stars of the binary system,
increases the star binding energy and thus translates to a decrease in their
masses. This in turn implies an increase with time of the binary period. Using
the pulsar data we obtain an upper limit on the allowed rate of mass reduction
: , where is the total mass of
the binary. This constrains exotic nuclear equations of state that predict
continuous neutrino emissions. The limit applies also to other channels of
energy loss, e.g. axion emission. Continued timing measurements of additional
binary pulsars, should yield a stronger limit in the future.Comment: 5 pages, Added a section on energy transport in the neutron star,
JHEP publishe
A Multicenter, Long-Term Study on Arrhythmias in Children with Ebstein Anomaly
To assess the prevalence, history, and treatment of arrhythmias, in particular preexcitation and WolffâParkinsonâWhite (WPW) syndrome, in patients with Ebstein anomaly (EA) during childhood and adolescence, we performed a multicenter retrospective study of all consecutive live-born patients with EA, diagnosed, and followed by pediatric cardiologists between 1980 and 2005 in The Netherlands. During a follow-up after EA diagnosis of 13Â years 3Â months (range: 6Â days to 28Â years 2Â months), 16 (17%) of the 93 pediatric EA patients exhibited rhythm disturbances. Nine patients showed arrhythmic events starting as of the neonatal period. Supraventricular tachycardia was noted in 11 patients. One patient died in the neonatal period due to intractable supraventricular tachycardia resulting in heart failure and one patient died at 5Â weeks of age most probably due to an arrhythmic event. The 14 surviving patients all show preexcitation, albeit 4 of them intermittently, and all have a right-sided accessory pathway location. Nine patients underwent catheter ablation of an accessory pathway. Only four patients are currently on antiarrhythmic drugs. The 17% prevalence of rhythm disturbances in pediatric EA patients, most commonly supraventricular arrhythmias, is significantly lower than in adult EA patients. Life-threatening rhythm disturbances are not frequent early in life. Symptomatic patients are well treated with radiofrequency catheter ablation
Constraints on the braneworld from compact stars
According to the braneworld idea, ordinary matter is confined on a three-dimensional space (brane) that is embedded in a higher-dimensional space-time where
gravity propagates. In this work, after reviewing the limits coming from general relativity, finiteness of pressure and causality on the brane, we derive observational constraints on the braneworld parameters from the existence of stable compact stars. The analysis is carried out by solving numerically the brane-modified TolmanâOppenheimerâVolkoff equations, using different representative equations
of state to describe matter in the star interior. The cases of normal dense matter, pure quark matter and hybrid matter are considered.info:eu-repo/semantics/publishedVersio
The NANOGrav Nine-year Data Set:Mass and Geometric Measurements of Binary Millisecond Pulsars
We analyze 24 binary radio pulsars in the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) nine-year data set. We make 14 significant measurements of the Shapiro delay, including new detections in four pulsar-binary systems (PSRs J0613â0200, J2017+0603, J2302+4442, and J2317+1439), and derive estimates of the binary-component masses and orbital inclination for these MSP-binary systems. We find a wide range of binary pulsar masses, with values as low as for PSR J1918â0642 and as high as for PSR J1614â2230 (both 68.3% credibility). We make an improved measurement of the Shapiro timing delay in the PSR J1918â0642 and J2043+1711 systems, measuring the pulsar mass in the latter system to be (68.3% credibility) for the first time. We measure secular variations of one or more orbital elements in many systems, and use these measurements to further constrain our estimates of the pulsar and companion masses whenever possible. In particular, we used the observed Shapiro delay and periastron advance due to relativistic gravity in the PSR J1903+0327 system to derive a pulsar mass of (68.3% credibility). We discuss the implications that our mass measurements have on the overall neutron-star mass distribution, and on the "mass/orbital-period" correlation due to extended mass transfer
The NANOGrav Nine-year Data Set:Astrometric Measurements of 37 Millisecond Pulsars
Using the nine-year radio-pulsar timing data set from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), collected at Arecibo Observatory and the Green Bank Telescope, we have measured the positions, proper motions, and parallaxes for 37 millisecond pulsars. We report twelve significant parallax measurements and distance measurements, and eighteen lower limits on distance. We compare these measurements to distances predicted by the NE2001 interstellar electron density model and find them to be in general agreement. We use measured orbital-decay rates and spin-down rates to confirm two of the parallax distances and to place distance upper limits on other sources; these distance limits agree with the parallax distances with one exception, PSR. J1024-0719, which we discuss at length. Using the proper motions of the 37 NANOGrav pulsars in combination with other published measurements, we calculate the velocity dispersion of the millisecond pulsar population in Galactocentric coordinates. We find the radial, azimuthal, and perpendicular dispersions to be 46, 40, and 24 km s(-1), respectively, in a model that allows for high-velocity outliers; or 81, 58, and 62 km s(-1) for the full population. These velocity dispersions are far smaller than those of the canonical pulsar population, and are similar to older Galactic disk populations. This suggests that millisecond pulsar velocities are largely attributable to their being an old population rather than being artifacts of their birth and evolution as neutron star binary systems. The components of these velocity dispersions follow similar proportions to other Galactic populations, suggesting that our results are not biased by selection effects
The additional value of patient-reported health status in predicting 1-year mortality after invasive coronary procedures: A report from the Euro Heart Survey on Coronary Revascularisation
Objective: Self-perceived health status may be helpful in identifying patients at high risk for adverse outcomes. The Euro Heart Survey on Coronary Revascularization (EHS-CR) provided an opportunity to explore whether impaired health status was a predictor of 1-year mortality in patients with coronary artery disease (CAD) undergoing angiographic procedures. Methods: Data from the EHS-CR that included 5619 patients from 31 member countries of the European Society of Cardiology were used. Inclusion criteria for the current study were completion of a self-report measure of health status, the EuroQol Questionnaire (EQ-5D) at discharge and information on 1-year follow-up, resulting in a study population of 3786 patients. Results: The 1-year mortality was 3.2% (n = 120). Survivors reported fewer problems on the five dimensions of the EQ-5D as compared with non-survivors. A broad range of potential confounders were adjusted for, which reached a p<0.10 in the unadjusted analyses. In the adjusted analyses, problems with self-care (OR 3.45; 95% CI 2.14 to 5.59) and a low rating (†60) on health status (OR 2.41; 95% CI 1.47 to 3.94) were the most powerful independent predictors of mortality, among the 22 clinical variables included in the analysis. Furthermore, patients who reported no problems on all five dimensions had significantly lower 1-year mortality rates (OR 0.47; 95% CI 0.28 to 0.81). Conclusions: This analysis shows that impaired health status is associated with a 2-3-fold increased risk of all-cause mortality in patients with CAD, independent of other conventional risk factors. These results highlight the importance of including patients' subjective experience of their own health status in the evaluation strategy to optimise risk stratification and management in clinical practice
The Doctoral Programme of the Twelfth International Conference on Principles and Practice of Constraint Programming, CP 2006, Nantes, France, September 24\u201329, 2006.
CP 2006 invites Ph.D. students to apply for the Doctoral Program, a forum held during the CP conference which provides an opportunity for a group of Ph.D. students to achieve visibility and discuss their research interests and career objectives with each other and established researchers in Constraint Programming and its related fields. After successful Doctoral Programmes in previous years, it is being run again this year for the sixth time.
The aims of the Doctoral Programme are the following:
* to provide a forum for Ph.D. students to present their current research, and receive feedback from other students and senior researchers;
* to promote contacts among Ph.D. students and senior researchers working in the same area;
* to exchange research experience;
* to support Ph.D. students with information and advice on academic, research and industrial careers;
* and to financially support its participants.
The program will consist of students' presentations and/or posters, and tutorials given by senior researchers in the field. In addition, each student will be matched to a mentor who is a senior researcher with similar research interests and who can advise the student on his/her research progress
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