Effect of Humic Acid on Seed Germination of Raphanus sativus L

Abstract: In the present study, we have tested the effect of humic acid on seed germination of Radish (Raphanus sativus). Seeds were soaked in various concentrations (0.1%, 0.25%, 0.5%, 0.75% and 1%) of humic acid at different time periods (10, 60, 120, 180 and 240 minutes). After 7 days, the seeds were analysed for their germination capacity, root and shoot length. The study infers that humic acid with the concentration of 0.25% showed maximum seed germination (100%) and the optimum shoot and root length was recorded as 6.175cm and 11.46cm respectively after 60 minutes soaking

Gravitational Waves From Known Pulsars: Results From The Initial Detector Era

We present the results of searches for gravitational waves from a large selection of pulsars using data from the most recent science runs (S6, VSR2 and VSR4) of the initial generation of interferometric gravitational wave detectors LIGO (Laser Interferometric Gravitational-wave Observatory) and Virgo. We do not see evidence for gravitational wave emission from any of the targeted sources but produce upper limits on the emission amplitude. We highlight the results from seven young pulsars with large spin-down luminosities. We reach within a factor of five of the canonical spin-down limit for all seven of these, whilst for the Crab and Vela pulsars we further surpass their spin-down limits. We present new or updated limits for 172 other pulsars (including both young and millisecond pulsars). Now that the detectors are undergoing major upgrades, and, for completeness, we bring together all of the most up-to-date results from all pulsars searched for during the operations of the first-generation LIGO, Virgo and GEO600 detectors. This gives a total of 195 pulsars including the most recent results described in this paper.United States National Science FoundationScience and Technology Facilities Council of the United KingdomMax-Planck-SocietyState of Niedersachsen/GermanyAustralian Research CouncilInternational Science Linkages program of the Commonwealth of AustraliaCouncil of Scientific and Industrial Research of IndiaIstituto Nazionale di Fisica Nucleare of ItalySpanish Ministerio de Economia y CompetitividadConselleria d'Economia Hisenda i Innovacio of the Govern de les Illes BalearsNetherlands Organisation for Scientific ResearchPolish Ministry of Science and Higher EducationFOCUS Programme of Foundation for Polish ScienceRoyal SocietyScottish Funding CouncilScottish Universities Physics AllianceNational Aeronautics and Space AdministrationOTKA of HungaryLyon Institute of Origins (LIO)National Research Foundation of KoreaIndustry CanadaProvince of Ontario through the Ministry of Economic Development and InnovationNational Science and Engineering Research Council CanadaCarnegie TrustLeverhulme TrustDavid and Lucile Packard FoundationResearch CorporationAlfred P. Sloan FoundationAstronom

The basic physics of the binary black hole merger GW150914

The first direct gravitational-wave detection was made by the Advanced Laser Interferometer Gravitational Wave Observatory on September 14, 2015. The GW150914 signal was strong enough to be apparent, without using any waveform model, in the filtered detector strain data. Here, features of the signal visible in the data are analyzed using concepts from Newtonian physics and general relativity, accessible to anyone with a general physics background. The simple analysis presented here is consistent with the fully general-relativistic analyses published elsewhere, in showing that the signal was produced by the inspiral and subsequent merger of two black holes. The black holes were each of approximately 35 M⊙, still orbited each other as close as ∼350 km apart and subsequently merged to form a single black hole. Similar reasoning, directly from the data, is used to roughly estimate how far these black holes were from the Earth, and the energy that they radiated in gravitational waves

Upper Limits on the Rates of Binary Neutron Star and Neutron-Star—Black-Hole Mergers from Advanced Ligo’s First Observing Run

We report here the non-detection of gravitational waves from the merger of binary neutron star systems and neutron-star–black-hole systems during the first observing run of Advanced LIGO. In particular we searched for gravitational wave signals from binary neutron star systems with component masses ∈ [1,3] M_⊙ and component dimensionless spins < 0.05. We also searched for neutron-star–black-hole systems with the same neutron star parameters, black hole mass ∈ [2,99] M_⊙ and no restriction on the black hole spin magnitude. We assess the sensitivity of the two LIGO detectors to these systems, and find that they could have detected the merger of binary neutron star systems with component mass distributions of 1.35 ± 0.13M_⊙ at a volume-weighted average distance of ~ 70 Mpc, and for neutron-star–black-hole systems with neutron star masses of 1.4M_⊙ and black hole masses of at least 5M_⊙, a volume-weighted average distance of at least ~ 110 Mpc. From this we constrain with 90% confidence the merger rate to be less than 12,600 Gpc^(-3) yr^(-1) for binary-neutron star systems and less than 3,600 Gpc^(-3) yr^(-1) for neutron-star–black-hole systems. We discuss the astrophysical implications of these results, which we find to be in tension with only the most optimistic predictions. However, we find that if no detection of neutron-star binary mergers is made in the next two Advanced LIGO and Advanced Virgo observing runs we would place significant constraints on the merger rates. Finally, assuming a rate of 10^(+20)_(-7) Gpc^(-3) yr^(-1) short gamma ray bursts beamed towards the Earth and assuming that all short gamma ray bursts have binary-neutron-star (neutron-star–black-hole) progenitors we can use our 90% confidence rate upper limits to constrain the beaming angle of the gamma-ray burst to be greater than 2.3^(+1.7º)_(-1.1) (4.3^(+3.1º)_(-1.9))

Exploring the sensitivity of next generation gravitational wave detectors

The second-generation of gravitational-wave detectors are just starting operation, and have already yielding their first detections. Research is now concentrated on how to maximize the scientific potential of gravitational-wave astronomy. To support this effort, we present here design targets for a new generation of detectors, which will be capable of observing compact binary sources with high signal-to-noise ratio throughout the Universe

Binary Black Hole Mergers in the First Advanced LIGO Observing Run

The first observational run of the Advanced LIGO detectors, from September 12, 2015 to January 19, 2016, saw the first detections of gravitational waves from binary black hole mergers. In this paper, we present full results from a search for binary black hole merger signals with total masses up to 100M⊙ and detailed implications from our observations of these systems. Our search, based on general-relativistic models of gravitational-wave signals from binary black hole systems, unambiguously identified two signals, GW150914 and GW151226, with a significance of greater than 5σ over the observing period. It also identified a third possible signal, LVT151012, with substantially lower significance and with an 87% probability of being of astrophysical origin. We provide detailed estimates of the parameters of the observed systems. Both GW150914 and GW151226 provide an unprecedented opportunity to study the two-body motion of a compact-object binary in the large velocity, highly nonlinear regime. We do not observe any deviations from general relativity, and we place improved empirical bounds on several high-order post-Newtonian coefficients. From our observations, we infer stellar-mass binary black hole merger rates lying in the range 9–240 Gpc^(−3)  yr^(−1). These observations are beginning to inform astrophysical predictions of binary black hole formation rates and indicate that future observing runs of the Advanced detector network will yield many more gravitational-wave detections