698 research outputs found

    Studies on the effect of chlorpyrifos (organophosphate) and cypermethrin (synthetic pyrethroid) on the growth of Paramecium

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    Interest in the toxicity of pesticides has increased as they enter waterways from agricultural and urban runoffs and may end up in aquatic environment and bioaccumulate in the food chain. The aim of this study was to determine the effect of two insecticides; Chlorpyrifos and Cypermethrin on aquatic protozoa (Paramecium). The test was carried out in laboratory, where Monoxenic culture of Paramecium was used to test the effect of Chlorpyrifos and Cypermethrin at 50, 25, 12.5, 6.25, 3.125, 1 respectively, at time interval of 24, 48, and 72 hours. The effect of Chlorpyrifos on Paramecium growth showed significant different with P value 0.0228, while for Cypermethrin, there was no significant difference with P value of 0.1333. The damage was more at 24hrs interval, as the number of population growth increased with time. Hence, the effect of the insecticides reduced. Conclusively, both insecticides showed harmful effect to Paramecium and may disturb the aquatic ecosystem.Keywords: Chlorpyrifos, Cypermethrin, Paramecium, Monoxenic culture, Toxicit

    Anomalous Cosmic Rays and their Ionization States

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    Ionization states of 16 individual anomalous cosmic ray events have been determined in the anuradha cosmic ray experiment conducted onboard Spacelab-3. The geomagnetic field was used as a rigidity filter for the energetic charged particles, and the upper limit on their ionization states is obtained by using the relation Z <= M.p.c/R/sub c/. Out of 16 events, 11 are found to be singly ionized and the other five events are consistent with their being in singly ionized states. The singly ionized nature of the anomalous cosmic ray particles suggests neutrals in the local interstellar space as their source

    Shear Viscosity to Entropy Density Ratio in Six Derivative Gravity

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    We calculate shear viscosity to entropy density ratio in presence of four derivative (with coefficient α\alpha') and six derivative (with coefficient α2\alpha'^2) terms in bulk action. In general, there can be three possible four derivative terms and ten possible six derivative terms in the Lagrangian. Among them two four derivative and eight six derivative terms are ambiguous, i.e., these terms can be removed from the action by suitable field redefinitions. Rest are unambiguous. According to the AdS/CFT correspondence all the unambiguous coefficients (coefficients of unambiguous terms) can be fixed in terms of field theory parameters. Therefore, any measurable quantities of boundary theory, for example shear viscosity to entropy density ratio, when calculated holographically can be expressed in terms of unambiguous coefficients in the bulk theory (or equivalently in terms of boundary parameters). We calculate η/s\eta/s for generic six derivative gravity and find that apparently it depends on few ambiguous coefficients at order α2\alpha'^2. We calculate six derivative corrections to central charges aa and cc and express η/s\eta/s in terms of these central charges and unambiguous coefficients in the bulk theory.Comment: 29 pages, no figure, V2, results and typos correcte

    Tau neutrino deep inelastic charged current interactions

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    The nu_mu -> nu_tau oscillation hypothesis will be tested through nu_tau production of tau in underground neutrino telescopes as well as long-baseline experiments. We provide the full QCD framework for the evaluation of tau neutrino deep inelastic charged current (CC) cross sections, including next-leading-order (NLO) corrections, charm production, tau threshold, and target mass effects in the collinear approximation. We investigate the violation of the Albright-Jarlskog relations for the structure functions F_4,5 which occur only in heavy lepton (tau) scattering. Integrated CC cross sections are evaluated naively over the full phase space and with the inclusion of DIS kinematic cuts. Uncertainties in our evaluation based on scale dependence, PDF errors and the interplay between kinematic and dynamical power corrections are discussed and/or quantified.Comment: 28 pages, 10 figure

    Higher Derivative Corrections to Shear Viscosity from Graviton's Effective Coupling

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    The shear viscosity coefficient of strongly coupled boundary gauge theory plasma depends on the horizon value of the effective coupling of transverse graviton moving in black hole background. The proof for the above statement is based on the canonical form of graviton's action. But in presence of generic higher derivative terms in the bulk Lagrangian the action is no longer canonical. We give a procedure to find an effective action for graviton (to first order in coefficient of higher derivative term) in canonical form in presence of any arbitrary higher derivative terms in the bulk. From that effective action we find the effective coupling constant for transverse graviton which in general depends on the radial coordinate rr. We also argue that horizon value of this effective coupling is related to the shear viscosity coefficient of the boundary fluid in higher derivative gravity. We explicitly check this procedure for two specific examples: (1) four derivative action and (2) eight derivative action (Weyl4Weyl^4 term). For both cases we show that our results for shear viscosity coefficient (up to first order in coefficient of higher derivative term) completely agree with the existing results in the literature.Comment: 0 + 23 page

    Weak Field Black Hole Formation in Asymptotically AdS Spacetimes

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    We use the AdS/CFT correspondence to study the thermalization of a strongly coupled conformal field theory that is forced out of its vacuum by a source that couples to a marginal operator. The source is taken to be of small amplitude and finite duration, but is otherwise an arbitrary function of time. When the field theory lives on Rd1,1R^{d-1,1}, the source sets up a translationally invariant wave in the dual gravitational description. This wave propagates radially inwards in AdSd+1AdS_{d+1} space and collapses to form a black brane. Outside its horizon the bulk spacetime for this collapse process may systematically be constructed in an expansion in the amplitude of the source function, and takes the Vaidya form at leading order in the source amplitude. This solution is dual to a remarkably rapid and intriguingly scale dependent thermalization process in the field theory. When the field theory lives on a sphere the resultant wave either slowly scatters into a thermal gas (dual to a glueball type phase in the boundary theory) or rapidly collapses into a black hole (dual to a plasma type phase in the field theory) depending on the time scale and amplitude of the source function. The transition between these two behaviors is sharp and can be tuned to the Choptuik scaling solution in Rd,1R^{d,1}.Comment: 50 pages + appendices, 6 figures, v2: Minor revisions, references adde

    Intercalibration of the barrel electromagnetic calorimeter of the CMS experiment at start-up

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    Calibration of the relative response of the individual channels of the barrel electromagnetic calorimeter of the CMS detector was accomplished, before installation, with cosmic ray muons and test beams. One fourth of the calorimeter was exposed to a beam of high energy electrons and the relative calibration of the channels, the intercalibration, was found to be reproducible to a precision of about 0.3%. Additionally, data were collected with cosmic rays for the entire ECAL barrel during the commissioning phase. By comparing the intercalibration constants obtained with the electron beam data with those from the cosmic ray data, it is demonstrated that the latter provide an intercalibration precision of 1.5% over most of the barrel ECAL. The best intercalibration precision is expected to come from the analysis of events collected in situ during the LHC operation. Using data collected with both electrons and pion beams, several aspects of the intercalibration procedures based on electrons or neutral pions were investigated

    Proximity effect at superconducting Sn-Bi2Se3 interface

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    We have investigated the conductance spectra of Sn-Bi2Se3 interface junctions down to 250 mK and in different magnetic fields. A number of conductance anomalies were observed below the superconducting transition temperature of Sn, including a small gap different from that of Sn, and a zero-bias conductance peak growing up at lower temperatures. We discussed the possible origins of the smaller gap and the zero-bias conductance peak. These phenomena support that a proximity-effect-induced chiral superconducting phase is formed at the interface between the superconducting Sn and the strong spin-orbit coupling material Bi2Se3.Comment: 7 pages, 8 figure

    Heavy Quarks and Heavy Quarkonia as Tests of Thermalization

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    We present here a brief summary of new results on heavy quarks and heavy quarkonia from the PHENIX experiment as presented at the "Quark Gluon Plasma Thermalization" Workshop in Vienna, Austria in August 2005, directly following the International Quark Matter Conference in Hungary.Comment: 8 pages, 5 figures, Quark Gluon Plasma Thermalization Workshop (Vienna August 2005) Proceeding
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