517 research outputs found
Intrinsic selection biases of ground-based gravitational wave searches for high-mass BH-BH mergers
The next generation of ground-based gravitational wave detectors may detect a
few mergers of comparable-mass M\simeq 100-1000 Msun ("intermediate-mass'', or
IMBH) spinning black holes. Black hole spin is known to have a significant
impact on the orbit, merger signal, and post-merger ringdown of any binary with
non-negligible spin. In particular, the detection volume for spinning binaries
depends significantly on the component black hole spins. We provide a fit to
the single-detector and isotropic-network detection volume versus (total) mass
and arbitrary spin for equal-mass binaries. Our analysis assumes matched
filtering to all significant available waveform power (up to l=6 available for
fitting, but only l<= 4 significant) estimated by an array of 64 numerical
simulations with component spins as large as S_{1,2}/M^2 <= 0.8. We provide a
spin-dependent estimate of our uncertainty, up to S_{1,2}/M^2 <= 1. For the
initial (advanced) LIGO detector, our fits are reliable for
(). In the online version of this
article, we also provide fits assuming incomplete information, such as the
neglect of higher-order harmonics. We briefly discuss how a strong selection
bias towards aligned spins influences the interpretation of future
gravitational wave detections of IMBH-IMBH mergers.Comment: 18 pages, 15 figures, accepted by PRD. v2 is version accepted for
publication, including minor changes in response to referee feedback and
updated citation
Gujarati Word Sense Disambiguation using Genetic Algorithm
Genetic algorithms (GAs) have widely been investigated to solve hard optimization problems, including the word sense disambiguation (WSD). This problem asks to determine which sense of a polysemous word is used in a given context. Several approaches have been investigated for WSD in English, French, German and some Indo-Aryan languages like Hindi, Marathi, Malayalam, etc. however, research on WSD in Guajarati Language is relatively limited. In this paper, an approach for Guajarati WSD using Genetic algorithm has been proposed which uses Knowledge based approach where Indo-Aryan WordNet for Guajarati is used as lexical database for WSD
Connecting Numerical Relativity and Data Analysis of Gravitational Wave Detectors
Gravitational waves deliver information in exquisite detail about
astrophysical phenomena, among them the collision of two black holes, a system
completely invisible to the eyes of electromagnetic telescopes. Models that
predict gravitational wave signals from likely sources are crucial for the
success of this endeavor. Modeling binary black hole sources of gravitational
radiation requires solving the Eintein equations of General Relativity using
powerful computer hardware and sophisticated numerical algorithms. This
proceeding presents where we are in understanding ground-based gravitational
waves resulting from the merger of black holes and the implications of these
sources for the advent of gravitational-wave astronomy.Comment: Appeared in the Proceedings of 2014 Sant Cugat Forum on Astrophysics.
Astrophysics and Space Science Proceedings, ed. C.Sopuerta (Berlin:
Springer-Verlag
Acheulean habitation in the Upper Son Valley, India: insights into early occupation and environment
Eight Acheulean sites are located in an under-researched ecological setting within the hilly terrain of the Upper Son Valley, India. A total of 1348 Acheulean artefacts have been identified across these sites, primarily preserved in high-energy depositional contexts, providing insights into the Pleistocene environment of hominin occupation and available lithic technology.Introduction Methods Results Conclusio
Deep vein thrombosis risk stratification in intensive care unit patients: a pressing need
Background: Risk stratification of deep vein thrombosis in patients admitted to ICU and incorporating DVT risk assessment score as a regular practice were the aim of the present study.Methods: This study was carried out in 67 patients admitted in ICU >18 years of age, over one year. Patients with confirmed DVT, <48 hours of stay, thrombocytopenia, diagnosed coagulation disorders, those who have received DVT prophylaxis in last 1 month and those with active bleeding were excluded. It was a cross sectional observational study. A SMART assessment score and pretest probability scoring card was used. Mechanical or pharmacological prophylaxis was given to those with moderate and high risk for DVT.Results: As per SMART assessment score 4.5%, 41.8%, 6% and 23.9% had no, moderate, high and highest risk of developing DVT. As per the pretest probability scores 76%, 20.9% and 3% were in low, moderate and high-risk group. Both scoring systems are comparable (p=0.001). There was significant association between paralysis (p value was 0.003), central venous access (p value was 0.006), patient bed ridden for >72 hours (p value was 0.009) and risk group.Conclusions: Prolonged bed rest, paralysis and central venous access are the most important contributing conditions for high risk of DVT. Risk stratification should be routinely performed in ICU. SMART assessment tool and pre-test probability scores are both equally efficacious in identifying high risk patients for DVT. Both mechanical and pharmacological means of DVT prophylaxis are equally effective in preventing DVT
Gravitational waves from eccentric intermediate mass binary black hole mergers
Owing to the difficulty of direct observation, mergers of intermediate-mass black hole binaries are relatively less understood compared to stellar-mass binaries; however, the gravitational waves from their last few orbits and ringdown fall in the band of ground-based detectors. Because the typical source is expected to circularize prior to entering LIGO or VIRGO's range, inspiral searches concentrate on circularized binaries. It is possible that events will be missed if there are sources with residual eccentricity. We study the variation of the signal to noise present in the dominant mode of the eccentric evolutions as a function of mass and eccentricity and also the relative contribution of the signal in the various spherical harmonic modes. The energy radiated in gravitational waves increases with eccentricity until the eccentricity becomes too high, leading to plunging trajectories, at which point the energy radiated decreases. This enhancement of the energy for initial eccentricities near the transition value translates into larger signal-to-noise ratios. Consequently despite the anticipated loss in the signal-to-noise ratio due to the use of quasi-circular detection templates, some eccentric signals potentially may be seen farther out than others
Implications For The Origin Of GRB 051103 From LIGO Observations
We present the results of a LIGO search for gravitational waves (GWs)
associated with GRB 051103, a short-duration hard-spectrum gamma-ray burst
(GRB) whose electromagnetically determined sky position is coincident with the
spiral galaxy M81, which is 3.6 Mpc from Earth. Possible progenitors for
short-hard GRBs include compact object mergers and soft gamma repeater (SGR)
giant flares. A merger progenitor would produce a characteristic GW signal that
should be detectable at the distance of M81, while GW emission from an SGR is
not expected to be detectable at that distance. We found no evidence of a GW
signal associated with GRB 051103. Assuming weakly beamed gamma-ray emission
with a jet semi-angle of 30 deg we exclude a binary neutron star merger in M81
as the progenitor with a confidence of 98%. Neutron star-black hole mergers are
excluded with > 99% confidence. If the event occurred in M81 our findings
support the the hypothesis that GRB 051103 was due to an SGR giant flare,
making it the most distant extragalactic magnetar observed to date.Comment: 8 pages, 3 figures. For a repository of data used in the publication,
go to: https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=15166 . Also see
the announcement for this paper on ligo.org at:
http://www.ligo.org/science/Publication-GRB051103/index.ph
Malignant placental trophoblastic tumour a diagnostic dilemma: rare association with focal segmental glomerulonephritis and cardiomyopathy
Placental site trophoblastic tumour (PSTT) is the rarest form of Gestational trophoblastic neoplasia (GTN).It has a wide clinical spectrum of presentation and its complications have a multi organ involvment. Inspite of the advances in HCG assays and sensitive unltrasounds, its diagnosis and course in every case is a mystery. However, it is only rarely associated with glomerulonephritis. Most cases have not been biopsied and the specific nature of renal involvement is not clearly understood. Here we report a case of PSTT with glomerulonephritis and cardiomyopathy
Sodium-glucose co-transporter-2 inhibitors as anti-diabetic agents: a review
The incidence and prevalence of Type 2 diabetes mellitus (T2DM) have been increasing worldwide. However, existing therapeutic classes of anti-diabetic drugs are not adequately effective in achieving and maintaining long-term glycemic control in the most patients. The majority of the drugs control blood sugar without addressing the basic pathology of insulin resistance and relative deficiency. Moreover, side effects such as hypoglycemia and weight gain, of both new and established drugs need to be considered prior to treating a patient. An emerging anti-hyperglycemic intervention, the sodium glucose co-transporter 2 (SGLT2) inhibitor acts by a novel mechanism. Under physiological conditions, SGLT2 accounts for 90% of the glucose re-absorption in the kidney, while the SGLT2 inhibitors result in an increase in urinary excretion of glucose and lower plasma glucose levels. Here, the pros and cons of SGLT2 inhibitors are considered, while approaching a patient with T2DM. The basic biochemistry and physiology underlying the mechanisms of SGLT2 inhibitors are discussed alongside its clinical pharmacology, with a focus on metabolic changes associated with urinary glucose loss. Finally, a consideration of Food and Drug Administration safety concerns associated with acidosis due to SGLT2 inhibitor usage is presented, to allow a complete understanding of the utility of these molecules in the light of existing T2DM therapies
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