1,555 research outputs found

    Blindly detecting orbital modulations of jets from merging supermassive black holes

    Full text link
    In the last few years before merger, supermassive black hole binaries will rapidly inspiral and precess in a magnetic field imposed by a surrounding circumbinary disk. Multiple simulations suggest this relative motion will convert some of the local energy to a Poynting-dominated outflow, with a luminosity 10^{43} erg/s * (B/10^4 G)^2(M/10^8 Msun)^2 (v/0.4 c)^2, some of which may emerge as synchrotron emission at frequencies near 1 GHz where current and planned wide-field radio surveys will operate. On top of a secular increase in power on the gravitational wave inspiral timescale, orbital motion will produce significant, detectable modulations, both on orbital periods and (if black hole spins are not aligned with the binary's total angular momenta) spin-orbit precession timescales. Because the gravitational wave merger time increases rapidly with separation, we find vast numbers of these transients are ubiquitously predicted, unless explicitly ruled out (by low efficiency ϵ\epsilon) or obscured (by accretion geometry f_{geo}). If the fraction of Poynting flux converted to radio emission times the fraction of lines of sight accessible fgeof_{geo} is sufficiently large (f_{geo} \epsilon > 2\times 10^{-4} for a 1 year orbital period), at least one event is accessible to future blind surveys at a nominal 10^4 {deg}^2 with 0.5 mJy sensitivity. Our procedure generalizes to other flux-limited surveys designed to investigate EM signatures associated with many modulations produced by merging SMBH binaries.Comment: Submitted to ApJ. v1 original submission; v2 minor changes in response to refere

    An Investigation Of Kinetic Effects Of Split Injection Timing On Low Temperature Combustion

    Get PDF
    Low temperature combustion (LTC) modes of operating internal combustion engines are of great interest for their potential to achieve high thermal efficiencies while maintaining low nitrogen oxide (NOX) and particulate matter emissions below levels requiring costly after-treatment systems. While various strategies for realizing LTC have been developed, including homogeneous charge compression ignition (HCCI), reactivity controlled compression ignition (RCCI) and premixed charge compression ignition (PCCI), a common challenge is the control of the kinetically-driven auto-ignition processes over appreciable load ranges. This study examines the chemical kinetics of split-injection timing and the kinetic effect of this parameter on combustion phasing and pressure rise rate. Detailed reaction mechanisms are applied in CHEMKIN-based kinetic simulations to model the production and composition of combustion intermediates produced by a pilot injection through different pressure-temperature histories. The influence of these intermediates on the combustion phasing of the following main fuel ignition is examined. Different pilot injection timings were tried keeping the main fuel addition timing constant. The temperature, pressure and rate of heat release profiles during the combustion cycle for varied pilot fuel injection timings were compared along with the species composition at the start of main fuel addition. The results will provide insight to the role of pilot injection timing on LTC control

    Constraints on the environment and energetics of the Broad-Line Ic SN2014ad from deep radio and X-ray observations

    Full text link
    Broad-line type Ic Supernovae (BL-Ic SNe) are characterized by high ejecta velocity (≳104\gtrsim 10^4 km s−1^{-1}) and are sometimes associated with the relativistic jets typical of long duration (≳2\gtrsim 2 s) Gamma-Ray Bursts (L-GRBs). The reason why a small fraction of BL-Ic SNe harbor relativistic jets is not known. Here we present deep X-ray and radio observations of the BL-Ic SN2014ad extending from 1313 to 930930 days post explosion. SN2014ad was not detected at either frequency and has no observational evidence of a GRB counterpart. The proximity of SN2014ad (d∼26d\sim 26 Mpc) enables very deep constraints on the progenitor mass-loss rate M˙\dot{M} and on the total energy of the fast ejecta EE. We consider two synchrotron emission scenarios for a wind-like circumstellar medium (CSM): (i) uncollimated non-relativistic ejecta, and (ii) off-axis relativistic jet. Within the first scenario our observations are consistent with GRB-less BL-Ic SNe characterized by a modest energy budget of their fast ejecta (E≲1045E \lesssim 10^{45} erg), like SNe 2002ap and 2010ay. For jetted explosions, we cannot rule out a GRB with E≲1051E \lesssim 10^{51} erg (beam-corrected) with a narrow opening angle (θj∼5∘\theta_j \sim 5^{\circ}) observed moderately off-axis (θobs≳30∘\theta_{\rm obs} \gtrsim 30^{\circ}) and expanding in a very low CSM density (M˙\dot{M} ≲10−6\lesssim 10^{-6} M⊙_{\odot} yr−1^{-1}). Our study shows that off-axis low-energy jets expanding in a low-density medium cannot be ruled out even in the most nearby BL-Ic SNe with extensive deep observations, and might be a common feature of BL-Ic SNe.Comment: 9 pages, 5 figures, accepted in Ap

    Molecular characterization of corneal ulcers causing Staphylococcus aureus

    Get PDF
    Background: The human eye is one of the most remarkable sensory systems. Human beings gather most of the information about the external environment through their eyes and thus rely on sight more than on any other sense, with the eye being the most sensitive organ we have. Molecular characterization of Staphylococcus aureus from the cases of corneal ulcers.Methods: A total of 300 samples of corneal ulcers collected from various ophthalmology hospitals, government hospital and clinical laboratories of different places of Maharashtra, India. The Isolates were identified based on the colony morphology and biochemical reaction. The isolates were subjected for antibiotic sensitivity test and perform its molecular characterization.Results: In present study, 39 coagulase positive Staphylococcus aureus, pathogenic bacteria isolated from corneal ulcers.Conclusions: Staphylococcus aureus is one of the most significant pathogens in bacterial keratitis. Early diagnosis and prompt treatment are needed to minimize the possibility of permanent vision loss and reduce structural damage to the cornea

    Impact of post biomethanated spentwash on soil properties, nutrient uptake and yield of soybean – wheat cropping sequence

    Get PDF
    A field experiment was conducted on Sawargaon series of isohyperthermic family of Vertic haplustepts to study the effect of application of primary treated biomethanated spentwash (PBSW) through irrigation on soil properties, nutrient uptake and yield of soybean – wheat cropping sequence. The bulk density and hydraulic conductivity of soil were improved in 100% recommended dose (RD) of N through PBSW with and without P chemical fertilizer at soil depths of 0-15 and 15-30 cm. The lowest soil pH, calcium carbonate and highest electrical conductivity, organic carbon, available K, exchangeable sodium (Na), exchangeable sodium percentage (ESP), cation exchange capacity (CEC), sodium adsorption ratio (SAR) and pooled bacterial, fungal and actinomycetes populations in surface (0-15 cm) soil depth were observed in 100% RD of N through PBSW + with and without P chemical fertilizer at all three soil depths (0-15, 15-30 and 30-60 cm) over the other treatments. The highest pooled available soil P was recorded in 50% RD of N through PBSW application through irrigation and remaining N and P through chemical fertilizers in all three soil depths. The significantly highest total NPK uptake by cropping sequence and highest mean Benefit : Cost (B:C) ratio of soybean and wheat was recorded in 25 % RD of N through PBSW + remaining N and P through chemical fertilizers over the rest of the treatments. The 25 % N-recommended dose of soybean and wheat crop can be replaced by application of PBSW through irrigation in sequence without disturbing soils by salt load

    Strain-Rate Frequency Superposition in Large-Amplitude Oscillatory Shear

    Full text link
    In a recent work, Wyss, {\it et.al.} [Phys. Rev. Lett., {\bf 98}, 238303 (2007)] have noted a property of `soft solids' under oscillatory shear, the so-called strain-rate frequency superposition (SRFS). We extend this study to the case of soft solids under large-amplitude oscillatory shear (LAOS). We show results from LAOS studies in a monodisperse hydrogel suspension, an aqueous gel, and a biopolymer suspension, and show that constant strain-rate frequency sweep measurements with soft solids can be superimposed onto master curves for higher harmonic moduli, with the {\it same} shift factors as for the linear viscoelastic moduli. We show that the behavior of higher harmonic moduli at low frequencies in constant strain-rate frequency sweep measurements is similar to that at large strain amplitudes in strain-amplitude sweep tests. We show surface plots of the harmonic moduli and the energy dissipation rate per unit volume in LAOS for soft solids, and show experimentally that the energy dissipated per unit volume depends on the first harmonic loss modulus alone, in both the linear and the nonlinear viscoelastic regime.Comment: 10 pages, 25 figures, accepted for publication in Physical Review E. Incorporates referee comment

    Dust in the wind: the role of recent mass loss in long gamma-ray bursts

    Full text link
    We study the late-time (t>0.5 days) X-ray afterglows of nearby (z<0.5) long Gamma-Ray Bursts (GRB) with Swift and identify a population of explosions with slowly decaying, super-soft (photon index Gamma_x>3) X-ray emission that is inconsistent with forward shock synchrotron radiation associated with the afterglow. These explosions also show larger-than-average intrinsic absorption (NH_x,i >6d21 cm-2) and prompt gamma-ray emission with extremely long duration (T_90>1000 s). Chance association of these three rare properties (i.e. large NH_x,i, super-soft Gamma_x and extreme duration) in the same class of explosions is statistically unlikely. We associate these properties with the turbulent mass-loss history of the progenitor star that enriched and shaped the circum-burst medium. We identify a natural connection between NH_x,i Gamma_x and T_90 in these sources by suggesting that the late-time super-soft X-rays originate from radiation reprocessed by material lost to the environment by the stellar progenitor before exploding, (either in the form of a dust echo or as reprocessed radiation from a long-lived GRB remnant), and that the interaction of the explosion's shock/jet with the complex medium is the source of the extremely long prompt emission. However, current observations do not allow us to exclude the possibility that super-soft X-ray emitters originate from peculiar stellar progenitors with large radii that only form in very dusty environments.Comment: 6 pages, Submitted to Ap

    Review on Automatic Car Parking Indicator System

    Get PDF
    Parking is costly and limited in almost every major city in the world. An Automatic car parking systems for meeting near term parking demand are needed. There is need to develop a vacant parking slot detection and tracking system. Around view monitor (AVM) image sequence makes it possible with 360-degree scene Bird’s eye view camera. Around view monitor (AVM) captures the image sequence and on combining of each images empty slot is detected. The Ultrasonic sensor is useful to determine the adjacent vehicle. Hierarchical tree structure based parking slot marking method is used to recognize the parking slot marking. After combining sequentially detected parking slot, empty parking slot is recognized and the driver has to select one of the empty parking slots and drive into it. DOI: 10.17762/ijritcc2321-8169.16048

    Spin-charge and spin-orbital coupling effects on spin dynamics in ferromagnetic manganites

    Full text link
    Correlation-induced spin-charge and spin-orbital coupling effects on spin dynamics in ferromagnetic manganites are calculated with realistic parameters in order to provide a quantitative comparison with experimental results for spin stiffness, magnon dispersion, magnon damping, anomalous zone-boundary magnon softening, and Curie temperature. The role of orbital degeneracy, orbital ordering, and orbital correlations on spin dynamics in different doping regimes is highlighted.Comment: 19 pages, 9 figure
    • …
    corecore