Yelling Fire and Hacking: Why the First Amendment Does Not Permit Distributing DVD Decryption Technology?

One of the consequences of the black-hole "no-hair" theorem in general relativity (GR) is that gravitational radiation (quasi-normal modes) from a perturbed Kerr black hole is uniquely determined by its mass and spin. Thus, the spectrum of quasi-normal mode frequencies have to be all consistent with the same value of the mass and spin. Similarly, the gravitational radiation from a coalescing binary black hole system is uniquely determined by a small number of parameters (masses and spins of the black holes and orbital parameters). Thus, consistency between different spherical harmonic modes of the radiation is a powerful test that the observed system is a binary black hole predicted by GR. We formulate such a test, develop a Bayesian implementation, demonstrate its performance on simulated data and investigate the possibility of performing such a test using previous and upcoming gravitational wave observations

Skolem Functions for Factored Formulas

Given a propositional formula F(x,y), a Skolem function for x is a function \Psi(y), such that substituting \Psi(y) for x in F gives a formula semantically equivalent to \exists F. Automatically generating Skolem functions is of significant interest in several applications including certified QBF solving, finding strategies of players in games, synthesising circuits and bit-vector programs from specifications, disjunctive decomposition of sequential circuits etc. In many such applications, F is given as a conjunction of factors, each of which depends on a small subset of variables. Existing algorithms for Skolem function generation ignore any such factored form and treat F as a monolithic function. This presents scalability hurdles in medium to large problem instances. In this paper, we argue that exploiting the factored form of F can give significant performance improvements in practice when computing Skolem functions. We present a new CEGAR style algorithm for generating Skolem functions from factored propositional formulas. In contrast to earlier work, our algorithm neither requires a proof of QBF satisfiability nor uses composition of monolithic conjunctions of factors. We show experimentally that our algorithm generates smaller Skolem functions and outperforms state-of-the-art approaches on several large benchmarks.Comment: Full version of FMCAD 2015 conference publicatio

An effectual template bank for the detection of gravitational waves from inspiralling compact binaries with generic spins

We report the construction of a three-dimensional template bank for the search for gravitational waves from inspiralling binaries consisting of spinning compact objects. The parameter space consists of two dimensions describing the mass parameters and one "reduced-spin" parameter, which describes the secular (non-precessing) spin effects in the waveform. The template placement is based on an efficient stochastic algorithm and makes use of the semi-analytical computation of a metric in the parameter space. We demonstrate that for "low-mass" ($m_1 + m_2 \lesssim 12\,M_\odot$) binaries, this template bank achieves effective fitting factors $\sim0.92$--$0.99$ towards signals from generic spinning binaries in the advanced detector era over the entire parameter space of interest (including binary neutron stars, binary black holes, and black hole-neutron star binaries). This provides a powerful and viable method for searching for gravitational waves from generic spinning low-mass compact binaries. Under the assumption that spin magnitudes of black-holes [neutron-stars] are uniformly distributed between 0--0.98 [0 -- 0.4] and spin angles are isotropically distributed, the expected improvement in the average detection volume (at a fixed signal-to-noise-ratio threshold) of a search using this reduced-spin bank is $\sim20-52\%$, as compared to a search using a non-spinning bank.Comment: Minor changes, version appeared in Phys. Rev.

Testing the no-hair nature of binary black holes using the consistency of multipolar gravitational radiation

Gravitational-wave (GW) observations of binary black holes offer the best probes of the relativistic, strong-field regime of gravity. Gravitational radiation in the leading order is quadrupolar. However, nonquadrupole (higher order) modes make appreciable contribution to the radiation from binary black holes with large mass ratios and misaligned spins. The multipolar structure of the radiation is fully determined by the intrinsic parameters (masses and spin angular momenta of the companion black holes) of a binary in quasicircular orbit. Following our previous work [S. Dhanpal, A. Ghosh, A. K. Mehta, P. Ajith, and B. S. Sathyaprakash, Phys. Rev. D 99, 104056 (2019).], we develop multiple ways of testing the consistency of the observed GW signal with the expected multipolar structure of radiation from binary black holes in general relativity. We call this a no-hair test of binary black holes as this is similar to testing the no-hair theorem for isolated black holes through mutual consistency of the quasinormal mode spectrum. We use Bayesian inference on simulated GW signals that are consistent/inconsistent with binary black holes in general relativity to demonstrate the power of the proposed tests. We also make estimate systematic errors arising as a result of neglecting companion spins

Detection of gravitational-wave bursts with chirplet-like template families

Gravitational Wave (GW) burst detection algorithms typically rely on the hypothesis that the burst signal is "locally stationary", that is it changes slowly with frequency. Under this assumption, the signal can be decomposed into a small number of wavelets with constant frequency. This justifies the use of a family of sine-Gaussian templates in the Omega pipeline, one of the algorithms used in LIGO-Virgo burst searches. However there are plausible scenarios where the burst frequency evolves rapidly, such as in the merger phase of a binary black hole and/or neutron star coalescence. In those cases, the local stationarity of sine-Gaussians induces performance losses, due to the mismatch between the template and the actual signal. We propose an extension of the Omega pipeline based on chirplet-like templates. Chirplets incorporate an additional parameter, the chirp rate, to control the frequency variation. In this paper, we show that the Omega pipeline can easily be extended to include a chirplet template bank. We illustrate the method on a simulated data set, with a family of phenomenological binary black-hole coalescence waveforms embedded into Gaussian LIGO/Virgo-like noise. Chirplet-like templates result in an enhancement of the measured signal-to-noise ratio.Comment: 8 pages, 6 figures. Submitted to Class. Quantum Grav. Special issue: Proceedings of GWDAW-14, Rome (Italy), 2010; fixed several minor issue

Depression, anxiety and stress among COVID positive pregnant women

Background: Impact of the news that patient is covid positive may increase the risk of depression and anxiety among the vulnerable population such as pregnant women. Aims of the study were to estimate the prevalence of depression, anxiety and stress among covid positive pregnant women. To evaluate the demographic and obstetric factors contributing to the psychological manifestations in covid positive pregnant women.Methods: A cross sectional descriptive study was conducted at a tertiary hospital of North Kerala from July to August 2020. The demographic and factors were recorded and DASS 21 self-reported questionnaire was used to assess depression, anxiety and stress.Results: We found that using the DASS 21 scoring system, 37.5% out of the 120 study subjects were having psychological symptoms either of depression, anxiety or stress. Depression was seen in 32 (26.7%), anxiety in 29 (24.2%) and stress in 14 (11.7%) of the study participants. The psychological symptoms of depression and anxiety were more pronounced in those with low education, unemployed and in the first and third trimester of pregnancy.Conclusions: The current study shows that COVID-19 positive pregnant women have a high prevalence of depression and anxiety. Our findings can be used to formulate psychological interventions to improve mental health and psychological resilience during the COVID-19 pandemic

Surrogate Buyers in Corporate Buying of Luxury Hotel Rooms

Hotel industry is a significant stakeholder in the Indian tourism sector. According to Knight Frank research, 2008 Indian hotel industry is currently adding about 42,022 five and four star category rooms in the major cities. Hotel demand has grown much faster than supply, but the need to market the hotels, optimally remains. The persons who handle the travel arrangements for corporate houses are not buying the hotel services for their own personal use. This is the reason why, they can be termed as surrogate buyers. An identification of the how these surrogate buyers contribute to sales of luxury hotels, is what the researchers are trying to establish through this research. A study of a stratified sample of Sales Managers of all the hotels which fall into the luxury category of hotels in the city of Kochi, Kerala is undertaken during the first quarter of 2012, using the tools like a questionnaire and personal interview of Sales managers of these hotels. Thus the observations were arrived at. Hotel managers have to recognize this fact and should try to pamper these surrogate buyers by creation of business relationships. Also we would like to argue that that out of all the room business received from corporate, almost all (up to 95%) are routed through these surrogate buyers and they are definitely a business source. Managing them can surely bring additional business for any luxury hotel. Keywords: Hotel, Bookers, Surrogate buyers, Corporate busines

COVID-19 symptoms-does pregnancy alter the course of the disease

Background: COVID-19 or corona virus 2 is a widespread pandemic taking a huge toll on the world population.it has a varied presentation in different age groups. Similarly, it has a poorer outcome in the elderly with various comorbidities and those who are immunocompromised. Though pregnancy is a relatively immunocompromised state studies have found that pregnant women have a less severe presentation. We have tried to assess this aspect of COVID-19 in pregnant women.Methods: We evaluated the records of 158 pregnant women who presented to our hospital from April 2020 till September 2020.Their symptoms at presentation were evaluated. we also noted the outcome of these pregnancies.Results: 16% of these were more than 34 weeks of period of gestation. 65.19% presented without any symptoms. 15.19% presented with fever. 10.75% presented with cough. 8.22% presented with headache. 5.69% presented with sore throat alone. 3.16% presented with breathlessness. 0.63% presented with anosmia alone, loss of taste, severe acute respiratory infection, vomiting, sore throat and breathlessness respectively. 54 patients delivered of which 7 delivered vaginally and there were 47 caesareans. Remaining patients after cure were discharged. There were 3 miscarriages. Two babies were found to be COVID-19 positive from nasopharyngeal swab taken on day 1, however this was a small number to indicate vertical transmission.Conclusion: Our study showed that a large proportion of pregnant patients presented without symptoms.it remains to be evaluated why this is so.it may provide us with clues on how to deal with disease in the general population

Covid 19, the Kerala experience: an observational, single centre retrospective study of outcome in covid positive pregnancies

Background: Covid 19 has spread across the world at an alarming rate. Approximately 4.05 million people have got infected worldwide resulting in around 279,000 deaths. Over 1 million people have recovered worldwide. Aim of this study was to determine whether course and severity of covid 19 is altered in pregnant women and whether covid 19 seemed to worsen the prognosis in pregnant women.Methods: Around 50 covid positive patients were admitted to this study hospital, a tertiary care referral hospital and medical college, between march and May 2020, 11 were pregnant. Authors collected their data retrospectively to understand the course of their disease till the period of recovery.Results: There were 6 patients above 31 weeks of whom one had elective repeat caesarean section, one had full term vaginal delivery, one is under follow up. Three patients had foetal distress necessitating emergency caesarean section. Of the remaining 5 patients with periods of gestation between 9-13 weeks, 1 of 24 weeks, 6 patients above 31 weeks, one had a miscarriage. Rest pregnancies are continuing and under follow up. 6 women had been symptomatic at admission, with mild symptoms of low-grade fever, sore throat and rhinitis. All were treated with hydroxychloroquine (HCQs). Those with respiratory symptoms like cough were also treated with oseltamivir. In view of high prevalence of H1N1 in the region. None of the women developed severe disease. The disease did not appear to worsen prognosis in pregnant women. The rate of recovery in pregnant women was similar to that seen in non-pregnant women and also men under the age of 40 years admitted in this study hospital.Conclusions: Covid 19 did not seem to worsen the prognosis in pregnant individuals when compared to rest of the population. The foetal outcomes also seemed favorable. However larger studies are required before concrete guidelines could be formulated for management of the disease in pregnancy