Stars Crushed by Black Holes. III. Mild Compression of Radiative Stars by Supermassive Black Holes

A tidal disruption event (TDE) occurs when the gravitational field of a supermassive black hole (SMBH) destroys a star. For TDEs in which the star enters deep within the tidal radius, such that the ratio of the tidal radius to the pericenter distance β satisfies β ≫ 1, the star is tidally compressed and heated. It was predicted that the maximum density and temperature attained during deep TDEs scale as ∝ β3 and ∝ β2, respectively, and nuclear detonation is triggered by β ≳ 5, but these predictions have been debated over the last four decades. We perform Newtonian smoothed-particle hydrodynamics simulations of deep TDEs between a Sun-like star and a 106 M⊙ SMBH for 2 ≤ β ≤ 10. We find that neither the maximum density nor temperature follow the ∝ β3 and ∝ β2 scalings or, for that matter, any power-law dependence, and that the maximum-achieved density and temperature are reduced by ∼1 order of magnitude compared to past predictions. We also perform simulations in the Schwarzschild metric and find that relativistic effects modestly increase the maximum density (by a factor of ≲1.5) and induce a time lag relative to the Newtonian simulations, which is induced by time dilation. We also confirm that the time the star spends at high density and temperature is a very small fraction of its dynamical time. We therefore predict that the amount of nuclear burning achieved by radiative stars during deep TDEs is minimal

Statističko-dinamička shema za prognozu u stvarnom vremenu primjenjena na vrlo snažnu ciklonalnu oluju \u27SIDR\u27 nad Bengalskim zaljevom u studenom 2007.

There is an operational requirement to formulate an objective procedure to handle operational cyclone forecasting work in a more efficient and effective way. In this paper we propose a four-step statistical-dynamical scheme for the real time application in cyclone forecasting work. The four-step scheme consists of (a) Analysis of Genesis Potential Parameter (GPP), (b) Estimation of Maximum Potential Intensity (MPI), (c) 72 hours Intensity Prediction and (d) Prediction of decaying intensity after the landfall. In November 2007, a very severe cyclonic storm \u27SIDR\u27 formed over the Bay of Bengal and hit the Bangladesh coast. In this paper, a four-step procedure is demonstrated for real time forecasting this cyclone. The results show that the GPP analysis at early stages of development can strongly indicate that the cyclone »SIDR« had enough potential to reach its cyclone stage. The MPI of the cyclone based on the SST (Sea Surface Temperature) values along the cyclone track is estimated to be 146 knots. The observed maximum intensity of the cyclone is found to be 79 % of its MPI. The 72 hours intensity prediction based on 00 UTC on 12 November could reproduce the intensity value of 109 knots, an underestimation of 6 knots. The subsequent updated forecasts are found to be realistic and useful. The 6-hourly decaying intensity forecast after the landfall shows an underestimation of 10 knots at 12 hours forecast and a significant improvement is noticed with the incorporation of correction factor. The study has documented the potentiality of the procedure for operational application.U svrhu uspješnije prognoze ciklona potrebno je formulirati što objektivnije radne procedure kojima se prognoza određuje. U ovoj studiji je predložena statističko-dinamička shema u četiri koraka prognoze ciklona u stvarnom vremenu. Shema se sastoji od (a) analize potencijalnih parametara nastanka ciklone (GPP), (b) procijene maksimalnog potencijalnog intenziteta (MPI), (c) 72-satne prognoze intenziteta i (d) prognoze smanjivanja intenziteta nakon što se ciklona približila obali. U studenom 2007. godine oformila se vrlo snažna ciklonalna oluja "SIDR" nad Bengalskim zaljevom koja je pogodila obalu Bangladeša. U ovoj studiji je prikazan postupak u četiri koraka u slučaju prognoze ove ciklone u stvarnom vremenu. Rezultati pokazuju da GPP analiza u ranom stadiju razvoja može izrazito nagovijestiti da je ciklona »SIDR« imala dovoljan potencijal da dođe do svog ciklonalnog stupnja. MPI ciklone je procijenjen na 146 čvorova na bazi vrijednosti površinske temperature mora duž putanje ciklone. Opaženi maksimalni intenzitet ciklone je oko 79 % njenog MPI. Prognozirani 72-satni intenzitet na temelju podataka iz 00 UTC od 12 studenog može reproducirati intenzitet od 109 čvorova uz podcjenjivanje od 6 čvorova. Sljedeće ažurirane prognoze bile su realistične i korisne. Šest-satna prognoza zamiranja intenziteta nakon što se ciklona približila obali pokazuje podcjenjivanje od 10 čvorova u 12-satnoj prognozi te je uključivanjem faktora korekcije uočeno značajno poboljšanje. Studija je pokazala potencijal ovog postupka za operativnu primjenu

Evaluation of potential rice (Oryza sativa L.) genotypes with different levels of N under rainfed shallow lowland situation

A field experiment was conducted to evaluate the yield of potential rice genotypes during kharif season, 2012 and 2013 at Rice Research Station, Bankura, West Bengal, India on sandy loam soil of slightly acidic in reaction (pH: 5.7). This experiment was conducted in split-plot design with three replications. The results indicated that 105 kg N ha-1, the yield attributes recorded maximum number of panicles m-2 (307.9), panicle length (25.3cm), panicle weight (2.32g), number of filled grains per panicle (117.8), 1000-grains weight (24.5g) and finally recorded highest grain yield (4.80 t ha-1) than lower fertilities. While, 70 kg N ha-1 was remained closed to 105 kg N ha-1 in number of panicles m-2, panicle weight and number of filled grains per panicle. Among the potential rice varieties ‘Sampriti’ (IET 21987) recorded the highest grain yield (4.66 t ha-1) under rainfed shallow lowland situation of red and laterite zone of West Bengal. The highest grain yield (4.80 t ha-1) was obtained at 105 kg N ha-1and it was statistically at par with 70 kg N ha-1 (4.62 t ha-1). Therefore, the increased in grain yield of rice by the varieties due to overall respective performance in growth and appreciable improvement in the yield attributing characters

Effect of methane on the conversion of HFC-134a in a dielectric barrier discharge non-equilibrium plasma reactor

The effect of methane on the conversion of HFC-134a (CF3CH2F) in a dielectric barrier discharge non-equilibrium plasma reactor was examined. Reactions were conducted in an argon bath gas and in the absence of oxygen and nitrogen. The products of the reaction include H2, HF, CHF3, CH2F2, C2H6, C3H8, C2H3F, CHF2CHF2, C2H4F2, C3H7F as well as a polymeric solid deposit. The polymeric materials are predominantly fluorine containing random copolymers, which can be categorised as fluoropolymers, constituted from various functional groups including CF3, CF2, CHF, CHF2, CH2F, CH2 and CH3. While the presence of methane in the feed stream reduces the conversion level of CF3CH2F, it also modifies the polymer architecture. The addition of 1.25% methane with 12.5% CF3CH2F in an argon bath gas at 100cm3min-1 feed rate reduces the conversion of CF3CH2F from 74.5% to 46.8% and increases the formation of HF from 1500μmolh-1 to 2640μmolh-1. The effect of methane addition on the electrical discharge and the reaction pathways are discussed

Comparative study of the decomposition of CH4 in a nonequilibrium plasma and under high temperature pyrolytic conditions

In this study, the decomposition of methane in a nonequilibrium plasma, where nitrogen and oxygen were excluded from the feed mixture, was investigated. The major product species formed under conditions where the conversion level of methane was relatively high (up to 50 %) were determined. Hydrogen, acetylene, ethylene, ethane and propane were the primary gaseous species identified, and a liquid fraction was detected, which was characterised by 1 H NMR and gel permeation chromatography. The product spectrum formed in the nonequilibrium plasma is compared to the species profile predicted from methane pyrolysis, where the feed composition, residence time and methane conversion levels used in the high temperature pyrolysis simulation matched those in the nonequilibrium plasma experimental reactor

Homologous Flares and Magnetic Field Topology in Active Region NOAA 10501 on 20 November 2003

We present and interpret observations of two morphologically homologous flares that occurred in active region (AR) NOAA 10501 on 20 November 2003. Both flares displayed four homologous H-alpha ribbons and were both accompanied by coronal mass ejections (CMEs). The central flare ribbons were located at the site of an emerging bipole in the center of the active region. The negative polarity of this bipole fragmented in two main pieces, one rotating around the positive polarity by ~ 110 deg within 32 hours. We model the coronal magnetic field and compute its topology, using as boundary condition the magnetogram closest in time to each flare. In particular, we calculate the location of quasiseparatrix layers (QSLs) in order to understand the connectivity between the flare ribbons. Though several polarities were present in AR 10501, the global magnetic field topology corresponds to a quadrupolar magnetic field distribution without magnetic null points. For both flares, the photospheric traces of QSLs are similar and match well the locations of the four H-alpha ribbons. This globally unchanged topology and the continuous shearing by the rotating bipole are two key factors responsible for the flare homology. However, our analyses also indicate that different magnetic connectivity domains of the quadrupolar configuration become unstable during each flare, so that magnetic reconnection proceeds differently in both events.Comment: 24 pages, 10 figures, Solar Physics (accepted

Effect of participatory women's groups facilitated by Accredited Social Health Activists on birth outcomes in rural eastern India: A cluster-randomised controlled trial

Background: A quarter of the world's neonatal deaths and 15% of maternal deaths happen in India. Few community-based strategies to improve maternal and newborn health have been tested through the country's government-approved Accredited Social Health Activists (ASHAs). We aimed to test the effect of participatory women's groups facilitated by ASHAs on birth outcomes, including neonatal mortality. Methods: In this cluster-randomised controlled trial of a community interve

Cost-Effectiveness of Risk-Stratified Colorectal Cancer Screening Based on Polygenic Risk: Current Status and Future Potential

Background: Although uniform colonoscopy screening reduces colorectal cancer (CRC) mortality, risk-based screening may be more efficient. We investigated whether CRC screening based on polygenic risk is a cost-effective alternative to current uniform screening, and if not, under what conditions it would be. Methods: The MISCAN-Colon model was used to simulate a hypothetical cohort of US 40-year-olds. Uniform screening was modeled as colonoscopy screening at ages 50, 60, and 70 years. For risk-stratified screening, individuals underwent polygenic testing with current and potential future discriminatory performance (area under the receiveroperating curve [AUC] of 0.60 and 0.65–0.80, respectively). Polygenic testing results were used to create risk groups, for which colonoscopy screening was optimized by varying the start age (40–60 years), en

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio