4,119 research outputs found

    OHS: OH-airglow Suppressor for the Subaru Telescope

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    This paper describes an OH-airglow Suppressor (OHS) for the infrared Nasmyth focus of the Subaru telescope. OHS has the capability of eliminating 224 airglow-lines in the JJ- and HH-bands, which are major sources of background radiation at near-infrared wavelengths up to 2 μ\mum. Specifically, it is a pre-optics system installed between the telescope and an infrared camera/spectrograph (CISCO). The suppressor reduces sky background emissions to 1/25 and its throughput is 40%. As a result, the S/N gain achieved with OHS is more than 1 mag compared to the typical spectroscopic approach. The limiting magnitude measured during a test observing run was found to be HH = 21.1 mag (λ/Δλ\lambda/\Delta\lambda = 210, S/N = 5) in the standard 4000 s exposure sequence.Comment: 6 pages, 9 figures. Accepted for publication in PASJ(2001

    Boron abundance and solar neutrino spectrum distortion

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    The presence of neutrinos from Boron decay in the flux observed on Earth is attested by the observation of their energy spectrum. Possible distortions of the spectrum investigated in current detectors are often interpreted in terms of evidence in favour or against various schemes of neutrino oscillations. We stress here that a distortion of the spectrum at high energies could also result from an increase in the ratio of neutrinos originating from (3^3He+p) and 8^8B reactions. While a 8^8B neutrino depletion would contribute to this effect, an increase in the Hep contribution seems also needed to reproduce the preliminary data.Comment: 8 pages, 2 figures; abstract and introduction rewritten to match the conclusions bette

    Rolling Tachyon Solution in Vacuum String Field Theory

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    We construct a time-dependent solution in vacuum string field theory and investigate whether the solution can be regarded as a rolling tachyon solution. First, compactifying one space direction on a circle of radius R, we construct a space-dependent solution given as an infinite number of *-products of a string field with center-of-mass momentum dependence of the form e^{-b p^2/4}. Our time-dependent solution is obtained by an inverse Wick rotation of the compactified space direction. We focus on one particular component field of the solution, which takes the form of the partition function of a Coulomb system on a circle with temperature R^2. Analyzing this component field both analytically and numerically using Monte Carlo simulation, we find that the parameter b in the solution must be set equal to zero for the solution to approach a finite value in the large time limit x^0\to\infty. We also explore the possibility that the self-dual radius R=\sqrt{\alpha'} is a phase transition point of our Coulomb system.Comment: 39 pages, 17 figures, v3: references adde

    Predicting Big Bang Deuterium

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    We present new upper and lower bounds to the primordial abundances of deuterium and helium-3 based on observational data from the solar system and the interstellar medium. Independent of any model for the primordial production of the elements we find (at the 95\% C.L.): 1.5×105(D/H)P10.0×1051.5 \times 10^{-5} \le (D/H)_P \le 10.0 \times 10^{-5} and (3He/H)P2.6×105(^3He/H)_P \le 2.6\times 10^{-5}. When combined with the predictions of standard big bang nucleosynthesis, these constraints lead to a 95\% C.L. bound on the primordial abundance of deuterium: (D/H)best=(3.51.8+2.7)×105(D/H)_{best} = (3.5^{+2.7}_{-1.8})\times 10^{-5}. Measurements of deuterium absorption in the spectra of high redshift QSOs will directly test this prediction. The implications of this prediction for the primordial abundances of helium-4 and lithium-7 are discussed, as well as those for the universal density of baryons.Comment: Revised version of paper to reflect comments of the referee and reply to suggestions of Copi, Schramm, and Turner regarding the overall analysis and treatment of chemical evolution of D and He-3. Best-fit D/H abundance changes from (2.3 + 3.0 - 1.0)x10^{-5} to (3.5 +2.7 - 1.8) x10^{-5}. See also hep-ph/950531

    Tensor Constructions of Open String Theories I: Foundations

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    The possible tensor constructions of open string theories are analyzed from first principles. To this end the algebraic framework of open string field theory is clarified, including the role of the homotopy associative A_\infty algebra, the odd symplectic structure, cyclicity, star conjugation, and twist. It is also shown that two string theories are off-shell equivalent if the corresponding homotopy associative algebras are homotopy equivalent in a strict sense. It is demonstrated that a homotopy associative star algebra with a compatible even bilinear form can be attached to an open string theory. If this algebra does not have a spacetime interpretation, positivity and the existence of a conserved ghost number require that its cohomology is at degree zero, and that it has the structure of a direct sum of full matrix algebras. The resulting string theory is shown to be physically equivalent to a string theory with a familiar open string gauge group.Comment: 62 pages, LaTe

    Prosomal-width-to-weight relationships in American horseshoe crabs (Limulus polyphemus): examining conversion factors used to estimate landings

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    Horseshoe crabs (Limulus polyphemus) are valued by many stakeholders, including the commercial fishing industry, biomedical companies, and environmental interest groups. We designed a study to test the accuracy of the conversion factors that were used by NOAA Fisheries and state agencies to estimate horseshoe crab landings before mandatory reporting that began in 1998. Our results indicate that the NOAA Fisheries conversion factor consistently overestimates the weight of male horseshoe crabs, particularly those from New England populations. Because of the inaccuracy of this and other conversion factors, states are now mandated to report the number (not biomass) and sex of landed horseshoe crabs. However, accurate estimates of biomass are still necessary for use in prediction models that are being developed to better manage the horseshoe crab fishery. We recommend that managers use the conversion factors presented in this study to convert current landing data from numbers to biomass of harvested horseshoe crabs for future assessments

    Comments on Supersymmetry Algebra and Contact Term in Matrix String Theory

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    Following hep-th/0309238 relating the matrix string theory to the light-cone superstring field theory, we write down two supercharges in the matrix string theory explicitly. After checking the supersymmetry algebra at the leading order, we proceed to discuss higher-order contact terms.Comment: 17 pages, no figures, v2: eq. (5.1) and related appendices corrected, v3: final version to appear in JHE

    Linking Conformation Change to Hemoglobin Activation Via Chain-Selective Time-resolved Resonance Raman Spectroscopy on Protoheme/Mesoheme Hybrids

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    Time-resolved Resonance Raman spectra are reported for Hb tetramers, in which the αand β chains are selectively substituted with mesoheme. The Soret absorption band shift in meso- relative to protoheme permits chain-selective excitation of heme RR spectra. The evolution of these spectra following HbCO photolysis show that geminate recombination rates and yields are the same for the two chains, consistent with recent results on 15N-heme isotopomer hybrids. The spectra also reveal systematic shifts in the deoxy-heme ν4 and νFe-His) RR bands, which are anti-correlated. These shifts are resolved for the successive intermediates in the protein structure, which have previously been determined from time-resolved UVRR spectra. Both chains show Fe-His bond compression in the immediate photoproduct, which relaxes during the formation of the first intermediate, Rdeoxy (0.07 μs), in which the proximal F-helix is proposed to move away from the heme. Subsequently, the Fe-His bond weakens, more so for the α than the β chains. The weakening is gradual for the β chains, but abrupt for the α chains, coinciding with completion of the R-T quaternary transition, at 20μs. Since the transition from fast- to slow-rebinding Hb also occurs at 20μs, the drop in the α chain νFe-His supports the localization of ligation restraint to tension in the Fe-His bond, at least in the α-chains. The mechanism is more complex in the β chains

    The Perturbative Spectrum of the Dressed Sliver

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    We analyze the fluctuations of the dressed sliver solution found in a previous paper, hep-th/0311198, in the operator formulation of Vacuum String Field Theory. We derive the tachyon wave function and then analyze the higher level fluctuations. We show that the dressing is responsible for implementing the transversality condition on the massless vector. In order to consistently deal with the singular k=0k=0 mode we introduce a string midpoint regulator and we show that it is possible to accommodate all the open string states among the solutions to the linearized equations of motion. We finally show how the dressing can give rise to the correct ratio between the energy density of the dressed sliver and the brane tension computed via the three-tachyons-coupling.Comment: 52 pages, v2: comment added in sec. 5, v3: one appendix added, comments added in introduction and conclusion, to appear on PR

    Higher Level Open String States from Vacuum String Field Theory

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    We construct massive open string states around a classical solution in the oscillator formulation of Vacuum String Field Theory. In order for the correct mass spectrum to be reproduced, the projection operators onto the modes of the left- and right-half of the string must have an anomalous eigenvalue 1/2, and the massive states are constructed using the corresponding eigenvector. We analyze numerically the projection operators by regularizing them to finite size matrices and confirm that they indeed have eigenvalue 1/2. Beside the desired massive states, we have spurious massive as well as massless states, which are infinitely degenerate. We show that these unwanted states can be gauged away.Comment: 16 pages, no figures, LaTeX, v2:minor correction
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