14,891 research outputs found

    Systems and methods for determining radio frequency interference

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    The presence, frequency and amplitude of radio frequency interference superimposed on communication links originating from a terrestrial region and including a relay in a geostationary spacecraft are determined by pointing a narrow beam antenna on the satellite at the terrestrial region. The level of noise radiated from the region to the antenna is measured at a terrestrial station that is usually remote from the region. Calibrating radio signals having a plurality of predetermined EIRP's (Effective Isotropic Radiated Power) and frequencies in the spectrum are transmitted from the region through the spacecraft narrow beam antenna back to the station. At the station, the levels of the received calibrating signals are separately measured for each of the frequency bands and EIRP's

    Fractional Superstrings with Space-Time Critical Dimensions Four and Six

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    We propose possible new string theories based on local world-sheet symmetries corresponding to extensions of the Virasoro algebra by fractional spin currents. They have critical central charges c=6(K+8)/(K+2)c=6(K+8)/(K+2) and Minkowski space-time dimensions D=2+16/KD=2+16/K for K2K\geq2 an integer. We present evidence for their existence by constructing modular invariant partition functions and the massless particle spectra. The dimension 44 and 66 strings have space-time supersymmetry.Comment: 9 page

    Root to Kellerer

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    We revisit Kellerer's Theorem, that is, we show that for a family of real probability distributions (μt)t[0,1](\mu_t)_{t\in [0,1]} which increases in convex order there exists a Markov martingale (St)t[0,1](S_t)_{t\in[0,1]} s.t.\ StμtS_t\sim \mu_t. To establish the result, we observe that the set of martingale measures with given marginals carries a natural compact Polish topology. Based on a particular property of the martingale coupling associated to Root's embedding this allows for a relatively concise proof of Kellerer's theorem. We emphasize that many of our arguments are borrowed from Kellerer \cite{Ke72}, Lowther \cite{Lo07}, and Hirsch-Roynette-Profeta-Yor \cite{HiPr11,HiRo12}.Comment: 8 pages, 1 figur

    Constraints on Primordial Nongaussiantiy from the High-Redshift Cluster MS1054--03

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    The implications of the massive, X-ray selected cluster of galaxies MS1054--03 at z=0.83z=0.83 are discussed in light of the hypothesis that the primordial density fluctuations may be nongaussian. We generalize the Press-Schechter (PS) formalism to the nongaussian case, and calculate the likelihood that a cluster as massive as MS1054 would appear in the EMSS. The probability of finding an MS1054-like cluster depends only on \omegam and the extent of primordial nongaussianity. We quantify the latter by adopting a specific functional form for the PDF, denoted ψλ,\psi_\lambda, which tends to Gaussianity for λ1,\lambda\gg 1, and show how λ\lambda is related to the more familiar statistic T,T, the probability of 3σ\ge 3\sigma fluctuations for a given PDF relative to a Gaussian. We find that Gaussian initial density fluctuations are consistent with the data on MS1054 only if \omegam\simlt 0.2. For \omegam\ge 0.25 a significant degree of nongaussianity is required, unless the mass of MS1054 has been substantially overestimated by X-ray and weak lensing data. The required amount of nongaussianity is a rapidly increasing function of \omegam for 0.25 \le \omegam \le 0.45, with λ1\lambda \le 1 (T \simgt 7) at the upper end of this range. For a fiducial \omegam=0.3, \omegal=0.7 universe, favored by several lines of evidence we obtain an upper limit λ10,\lambda \le 10, corresponding to a T3.T\ge 3. This finding is consistent with the conclusions of Koyama, Soda, & Taruya (1999), who applied the generalized PS formalism to low (z\simlt 0.1) and intermediate (z\simlt 0.6) redshift cluster data sets.Comment: 15 pages, 11 figures, submitted to the Astrophysical Journal, uses emulateapj.st

    Gambaran pencemaran antibiotik pada sistem pembuangan limbah cair di RSUP Prof. Dr. R. D. Kandou Manado

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    Background : Hospitals in Indonesia produce large amounts of waste water, this can be infectious, contain pathogenic microorganisms and chemicals that are harmful to health and the surrounding environment. Previous studies found antibiotics as one of the ingredients in hospital wastewater, and most of the microorganisms identified from wastewater were reported to be resistant to commonly used antibiotics.Purpose : This study aims to determine the contamination of antibiotics in the wastewater system at  RSUP Prof. Dr. R. D. Kandou Manado by doing isolation and bacteria and antibiotic sensitivity tests.Methods: The type of research used is descriptive quantitative research. The sample used is wastewater from the inlet and outlet points. Isolation and bacteria were adjusted according to Bergey's Manual of Determinative Bacteriology. Sensitivity test using Kirby Bauer method with antibiotics used is clindamycin. The results are interpreted based on CLSI.Results: The bacteria that were identified were Bacillus spp., Streptococcus spp., Escherichia spp. and Staphylococcus spp.. These bacteria showed an interpretation of resistance to clindamycin, except for Bacillus spp. which could not be interpreted.Conclusion: Based on the results of the study that the bacteria Streptococcus spp., Escherichia spp. and Staphylococcus spp. which were found to be resistant in the sensitivity test, indicated the presence of antibiotic contamination in the wastewater at RSUP Prof. Dr. R. D. Kandou Manado.Keywords: Hospital waste water, identification of bacteria, sensitivity tes

    Electromagnetic dipole moments of charged baryons with bent crystals at the LHC

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    We propose a unique program of measurements of electric and magnetic dipole moments of charm, beauty and strange charged baryons at the LHC, based on the phenomenon of spin precession of channeled particles in bent crystals. Studies of crystal channeling and spin precession of positively- and negatively-charged particles are presented, along with feasibility studies and expected sensitivities for the proposed experiment using a layout based on the LHCb detector.Comment: 19 pages, 13 figure

    Notes on Recent Cases

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    Notes on recent cases by Edward P. McGuire, Henry Hasley, Thomas V. Happer, W. F. Craig, John P. Bersheid, Marc Wonderlin, Herbert J. Nester

    Development of large radii half-wave plates for CMB satellite missions

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    The successful European Space Agency (ESA) Planck mission has mapped the Cosmic Microwave Background (CMB) temperature anisotropy with unprecedented accuracy. However, Planck was not designed to detect the polarised components of the CMB with comparable precision. The BICEP2 collaboration has recently reported the first detection of the B-mode polarisation. ESA is funding the development of critical enabling technologies associated with B-mode polarisation detection, one of these being large diameter half-wave plates. We compare different polarisation modulators and discuss their respective trade-offs in terms of manufacturing, RF performance and thermo-mechanical properties. We then select the most appropriate solution for future satellite missions, optimized for the detection of B-modes.Comment: 16 page

    Sensitivities of Low Energy Reactor Neutrino Experiments

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    The low energy part of the reactor neutrino spectra has not been experimentally measured. Its uncertainties limit the sensitivities in certain reactor neutrino experiments. The origin of these uncertainties are discussed, and the effects on measurements of neutrino interactions with electrons and nuclei are studied. Comparisons are made with existing results. In particular, the discrepancies between previous measurements with Standard Model expectations can be explained by an under-estimation of the low energy reactor neutrino spectra. To optimize the experimental sensitivities, measurements for \nuebar-e cross-sections should focus on events with large (>>1.5 MeV) recoil energy while those for neutrino magnetic moment searches should be based on events <<100 keV. The merits and attainable accuracies for neutrino-electron scattering experiments using artificial neutrino sources are discussed.Comment: 25 pages, 9 figure
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