408 research outputs found

    Cosmological Constraints from calibrated Yonetoku and Amati relation implies Fundamental plane of Gamma-ray bursts

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    We consider two empirical relations using data only from the prompt emission of Gamma-Ray Bursts (GRBs), peak energy (EpE_p) - peak luminosity (LpL_p) relation (so called Yonetoku relation) and EpE_p-isotropic energy (EisoE_{\rm iso}) relation (so called Amati relation). We first suggest the independence of the two relations although they have been considered similar and dependent. From this viewpoint, we compare constraints on cosmological parameters, Ωm\Omega_m and ΩΛ\Omega_{\Lambda}, from the Yonetoku and Amati relations calibrated by low-redshift GRBs with z<1.8z < 1.8. We found that they are different in 1-σ\sigma level, although they are still consistent in 2-σ\sigma level. This and the fact that both Amati and Yonetoku relations have systematic errors larger than statistical errors suggest the existence of a hidden parameter of GRBs. We introduce the luminosity time TLT_L defined by TL≡Eiso/LpT_L\equiv E_{\rm iso}/L_p as a hidden parameter to obtain a generalized Yonetoku relation as (Lp/1052ergs−1)=10−3.88±0.09(Ep/keV)1.84±0.04(TL/s)−0.34±0.04(L_p/{10^{52} \rm{erg s^{-1}}}) = 10^{-3.88\pm0.09}(E_p/{\rm{keV}})^{1.84\pm0.04} (T_L/{\rm{s}})^{-0.34\pm0.04}. The new relation has much smaller systematic error, 30%, and can be regarded as "Fundamental plane" of GRBs. We show a possible radiation model for this new relation. Finally we apply the new relation for high-redshift GRBs with 1.8<z<5.61.8 < z < 5.6 to obtain (Ωm,ΩΛ)=(0.16−0.06+0.04,1.20−0.09+0.03)(\Omega_m,\Omega_{\Lambda}) = (0.16^{+0.04}_{-0.06},1.20^{+0.03}_{-0.09}), which is consistent with the concordance cosmological model within 2-σ\sigma level.Comment: 5 pages, 6 figures, published in JCA

    A Compact Gas Cerenkov Detector with Novel Optics

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    We discuss the design and performance of a threshold Cerenkov counter for identification of charged hadrons. The radiator is pressurized gas, which is contained in thin-walled cylindrical modules. A mirror system of novel design transports Cerenkov photons to photomultiplier tubes. This system is compact, contains relatively little material, and has a large fraction of active volume. A prototype of a module designed for the proposed CLEO III detector has been studied using cosmic rays. Results from these studies show good agreement with a detailed Monte Carlo simulation of the module and indicate that it should achieve separation of pions and kaons at the 2.5-3.0sigma level in the momentum range 0.8-2.8 GeV/c. We predict performance for specific physics analyses using a GEANT-based simulation package.Comment: Submitted to NIM. 23 pages, 11 postscript figures. Postscript file is also available at http://w4.lns.cornell.edu/public/CLNS/199

    Development of Short-Form Versions of the Screener and Opioid Assessment for Patients with Pain-Revised (SOAPP-R):A Proof-of-Principle Study

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    BACKGROUND: The Screener and Opioid Assessment for Patients with Pain-Revised (SOAPP-R) is a 24-item questionnaire designed to assess risk of aberrant medication-related behaviors in chronic pain patients. The introduction of short forms of the SOAPP-R may save time and increase utilization by practitioners. OBJECTIVE: To develop and evaluate candidate SOAPP-R short forms. DESIGN: Retrospective study. SETTING: Pain centers. SUBJECTS: Four hundred and twenty-eight patients with chronic noncancer pain. METHODS: Subjects had previously been administered the full-length version of the SOAPP-R and been categorized as positive or negative for aberrant medication-related behaviors via the Aberrant Drug Behavior Index (ADBI). Short forms of the SOAPP-R were developed using lasso logistic regression. Sensitivity, specificity, and area under the curve (AUC) of all forms were calculated with respect to the ADBI using the complete data set, training-test analysis, and 10-fold cross-validation. The coefficient alpha of each form was also calculated. An external set of 12 pain practitioners reviewed the forms for content. RESULTS: In the complete data set analysis, a form of 12 items exhibited sensitivity, specificity, and AUC greater than or equal to those of the full-length SOAPP-R (which were 0.74, 0.67, and 0.76, respectively). The short form had a coefficient alpha of 0.76. In the training-test analysis and 10-fold cross-validation, it exhibited an AUC value within 0.01 of that of the full-length SOAPP-R. The majority of external practitioners reported a preference for this short form. CONCLUSIONS: The 12-item version of the SOAPP-R has potential as a short risk screener and should be tested prospectively

    Observational Constraints on Cosmological Models with the Updated Long Gamma-Ray Bursts

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    In the present work, by the help of the newly released Union2 compilation which consists of 557 Type Ia supernovae (SNIa), we calibrate 109 long Gamma-Ray Bursts (GRBs) with the well-known Amati relation, using the cosmology-independent calibration method proposed by Liang {\it et al.}. We have obtained 59 calibrated high-redshift GRBs which can be used to constrain cosmological models without the circularity problem (we call them ``Hymnium'' GRBs sample for convenience). Then, we consider the joint constraints on 7 cosmological models from the latest observational data, namely, the combination of 557 Union2 SNIa dataset, 59 calibrated Hymnium GRBs dataset (obtained in this work), the shift parameter RR from the WMAP 7-year data, and the distance parameter AA of the measurement of the baryon acoustic oscillation (BAO) peak in the distribution of SDSS luminous red galaxies. We also briefly consider the comparison of these 7 cosmological models.Comment: 19 pages, 3 tables, 10 figures, revtex4; v2: accepted for publication in JCAP; v3: published versio

    Higher Order Polarizabilities of the Proton

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    Compton scattering results are used to probe proton structure via measurement of higher order polarizabilities. Values for αE2p,βE2p,αEνp,\alpha_{E2}^p,\beta_{E2}^p,\alpha_{E\nu}^p, βEνp\beta_{E\nu}^p determined via dispersion relations are compared to predictions based upon chiral symmetry and from the constituent quark model. Extensions to spin-polarizabilities are also discussed.Comment: 18 pages, revised version with one reference adde

    Effective theory of the Delta(1232) in Compton scattering off the nucleon

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    We formulate a new power-counting scheme for a chiral effective field theory of nucleons, pions, and Deltas. This extends chiral perturbation theory into the Delta-resonance region. We calculate nucleon Compton scattering up to next-to-leading order in this theory. The resultant description of existing γ\gammap cross section data is very good for photon energies up to about 300 MeV. We also find reasonable numbers for the spin-independent polarizabilities αp\alpha_p and βp\beta_p.Comment: 29 pp, 9 figs. Minor revisions. To be published in PR

    Compton Scattering and the Spin Structure of the Nucleon at Low Energies

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    We analyze polarized Compton scattering which provides information on the spin-structure of the nucleon. For scattering processes with photon energies up to 100 MeV the spin-structure dependence can be encoded into four independent parameters-the so-called spin-polarizabilities γi,i=1...4\gamma_i, i=1...4 of the nucleon, which we calculate within the framework of the "small scale expansion" in SU(2) baryon chiral perturbation theory. Specific application is made to "forward" and "backward" spin- polarizabilities.Comment: 8 pages revtex file, separation between pion-pole and regular contributions detailed + minor wording changes, results and conclusions unchange

    Dose-dependent activation of gene expression is achieved using CRISPR and small molecules that recruit endogenous chromatin machinery

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    Gene expression can be activated or suppressed using CRISPR­–Cas9 systems. However, tools that enable dose-dependent activation of gene expression without the use of exogenous transcription regulatory proteins are lacking. Here we describe chemical epigenetic modifiers (CEMs) designed to activate the expression of target genes by recruiting components of the endogenous chromatin-activating machinery, eliminating the need for exogenous transcriptional activators. The system has two parts: catalytically inactive Cas9 (dCas9) in complex with FK506-binding protein (FKBP) and a CEM consisting of FK506 linked to a molecule that interacts with cellular epigenetic machinery. We show that CEMs upregulate gene expression at target endogenous loci up to 20-fold or more depending on the gene. We also demonstrate dose-dependent control of transcriptional activation, function across multiple diverse genes, reversibility of CEM activity and specificity of our best-in-class CEM across the genome

    Ab initio Quantum and ab initio Molecular Dynamics of the Dissociative Adsorption of Hydrogen on Pd(100)

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    The dissociative adsorption of hydrogen on Pd(100) has been studied by ab initio quantum dynamics and ab initio molecular dynamics calculations. Treating all hydrogen degrees of freedom as dynamical coordinates implies a high dimensionality and requires statistical averages over thousands of trajectories. An efficient and accurate treatment of such extensive statistics is achieved in two steps: In a first step we evaluate the ab initio potential energy surface (PES) and determine an analytical representation. Then, in an independent second step dynamical calculations are performed on the analytical representation of the PES. Thus the dissociation dynamics is investigated without any crucial assumption except for the Born-Oppenheimer approximation which is anyhow employed when density-functional theory calculations are performed. The ab initio molecular dynamics is compared to detailed quantum dynamical calculations on exactly the same ab initio PES. The occurence of quantum oscillations in the sticking probability as a function of kinetic energy is addressed. They turn out to be very sensitive to the symmetry of the initial conditions. At low kinetic energies sticking is dominated by the steering effect which is illustrated using classical trajectories. The steering effects depends on the kinetic energy, but not on the mass of the molecules. Zero-point effects lead to strong differences between quantum and classical calculations of the sticking probability. The dependence of the sticking probability on the angle of incidence is analysed; it is found to be in good agreement with experimental data. The results show that the determination of the potential energy surface combined with high-dimensional dynamical calculations, in which all relevant degrees of freedon are taken into account, leads to a detailed understanding of the dissociation dynamics of hydrogen at a transition metal surface.Comment: 15 pages, 9 figures, subm. to Phys. Rev.
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