4,512 research outputs found

    All-Sky Search for Gravitational-Wave Bursts in the First Joint LIGO-GEO-Virgo Run

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    We present results from an aU-sky search for unmodeled gravitational-wave bursts in the data collected by the LIGO, GEO 600 and Virgo detectors between November 2006 and October 2007. The search is performed. by three different analysis algorithms over the frequency band 50 - 6000 Hz. Data are analyzed for times with at least two of the four LIGO-Virgo detectors in coincident operation, with a total live time of 266 days, No events produced by the search algorithms survive the selection cuts. We set a frequentist upper limit on the rate of gravitational-wave bursts impinging on our network of detectors. When combined with the previous LIGO search of the data collected between November 2005 and November 2006, the upper limit on the rate of detectable gra.vitational. wave bursts in the 64-2048 Hz band is 2,0 events per year at 90% confidence. We also present event rate versus strength exclusion plots for several types of plausible burst waveforms. The sensitivity of the combined search is expressed in terms of the root-sum-squared strain amplitude for a variety of simulated waveforms and lies in the range 6 X 10(exp -22) Hz(exp - 1/2) to 2 X 10(exp -20) Hz(exp -l/2). This is the first untriggered burst search to use data from the LIGO and Virgo detectors together, and the most sensitive untriggered burst search performed so far

    Arm cavity resonant sideband control for laser interferometric gravitational wave detectors

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    We present a new optical control scheme for a laser interferometric gravitational wave detector that has a high degree of tolerance to interferometer spatial distortions and noise on the input light. The scheme involves resonating the rf sidebands in an interferometer arm cavity

    Beyond the single-atom response in absorption lineshapes: Probing a dense, laser-dressed helium gas with attosecond pulse trains

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    We investigate the absorption line shapes of laser-dressed atoms beyond the single-atom response, by using extreme ultraviolet (XUV) attosecond pulse trains to probe an optically thick helium target under the influence of a strong infrared (IR) field. We study the interplay between the IR-induced phase shift of the microscopic time-dependent dipole moment and the resonant-propagation-induced reshaping of the macroscopic XUV pulse. Our experimental and theoretical results show that as the optical depth increases, this interplay leads initially to a broadening of the IR-modified line shape, and subsequently to the appearance of new, narrow features in the absorption line.Comment: 5 pages, 5 figure

    Genome-wide linkage analysis for aggressive prostate cancer in Utah high risk pedigrees

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    posterResearch has consistently shown that genetics plays a critical role in prostate cancer (CaP) development, but the identification of CaP genes has proven to be very difficult. Hereditary prostate cancer is a complex disease involving numerous genes and variable phenotypic expression. This heterogeneity has led researchers to pursue genes associated with alternative phenotypes for CaP, such as tumor aggressiveness. Several recent linkage studies have used clinical and pathological data to define CaP aggressiveness as a qualitative trait. The International Consortium for Prostate Cancer Genetics (ICPCG) recently completed such an analysis using pooled data from 11 member institutions. This analysis required all families be small to moderate in size in order to facilitate standard linkage analysis software. Hence, although the ICPCG analysis included data from the Utah prostate cancer pedigree resource, the Utah pedigrees were not analyzed in their complete form. Specifically, pedigrees were divided and trimmed before analysis, which reduced the power of the analysis to detect predisposition loci. Here we present the results of a genome-wide scan for aggressive prostate cancer predisposition loci utilizing the full Utah pedigrees

    Genetic susceptibility of prostate cancer: genome-wide screen of ""non-aggressive"" disease

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    posterResearch has consistently shown that genetics plays a critical role in prostate cancer (CaP) development, but the identification of CaP genes has proven to be very difficult. Hereditary prostate cancer is a complex disease believed to involve numerous genes and variable penetrance. It has been proposed that studying alternative, highly homogenous phenotypes related to CaP may be a solution for overcoming the apparent heterogeneity that has hindered the identification of susceptibility genes. Several recent studies have applied this idea to "aggressive" or "clinically significant" cases of CaP. Using the resources of the Utah Population Database, we identified two phenotypes often associated with non-aggressive disease that show significant familiality. We present those results here

    Survey of excess familiality in prostate cancer

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    posterProstate cancer (PCa) is the most commonly diagnosed cancer among men, and has long been recognized to occur in familial clusters. However, identification of genes predisposing individuals to prostate cancer has been difficult. Putative PCa predisposition loci identified by genetic linkage have been reported on almost all chromosomes, but successful confirmation reports have been rare. PCa is a complex disease likely involving multiple genes and variable phenotypic expression. As a step toward understanding PCa heterogeneity, we used the resources of the Utah Population Database to review several PCa-related phenotypes for excess familiality. PCa subgroups that can be shown to have a strong familial component become candidates for linkage analysis and other genetic testing to determine the genetic basis for the observed phenotype

    Ninja data analysis with a detection pipeline based on the Hilbert-Huang Transform

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    The Ninja data analysis challenge allowed the study of the sensitivity of data analysis pipelines to binary black hole numerical relativity waveforms in simulated Gaussian noise at the design level of the LIGO observatory and the VIRGO observatory. We analyzed NINJA data with a pipeline based on the Hilbert Huang Transform, utilizing a detection stage and a characterization stage: detection is performed by triggering on excess instantaneous power, characterization is performed by displaying the kernel density enhanced (KD) time-frequency trace of the signal. Using the simulated data based on the two LIGO detectors, we were able to detect 77 signals out of 126 above SNR 5 in coincidence, with 43 missed events characterized by signal to noise ratio SNR less than 10. Characterization of the detected signals revealed the merger part of the waveform in high time and frequency resolution, free from time-frequency uncertainty. We estimated the timelag of the signals between the detectors based on the optimal overlap of the individual KD time-frequency maps, yielding estimates accurate within a fraction of a millisecond for half of the events. A coherent addition of the data sets according to the estimated timelag eventually was used in a characterization of the event.Comment: Accepted for publication in CQG, special issue NRDA proceedings 200

    Interplay between resonant enhancement and quantum path dynamics in harmonic generation in helium

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    We present a theoretical study of the influence of resonant enhancement on quantum path dynamics in the generation of harmonics above and below the ionization threshold in helium. By varying the wavelength and intensity of the driving field from 425 to 500 nm and from 30 to 140 TW/cm2, respectively, we identify enhancements of harmonics 7, 9, and 11 that correspond to multiphoton resonances between the ground state and the Stark-shifted 1s2p,1s3p, and 1s4p excited states. A time-frequency analysis of the emission shows that both the short and the long quantum path contributions to the harmonic yield are enhanced through these bound-state resonances. We analyze the subcycle time structure of the ninth harmonic yield in the vicinity of the resonances and find that on resonance the long trajectory contribution is phase shifted by approximately π/4. Finally, we compare the single atom and the macroscopic response of a helium gas and find that while the subcycle time profiles are slightly distorted by propagation effects, the phase shift of the long-trajectory contribution is still recognizable

    Search for Gravitational Waves from Intermediate Mass Binary Black Holes

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    We present the results of a weakly modeled burst search for gravitational waves from mergers of non-spinning intermediate mass black holes (IMBH) in the total mass range 100-450 solar Mass and with the component mass ratios between 1:1 and 4:1. The search was conducted on data collected by the LIGO and Virgo detectors between November of 2005 and October of 2007. No plausible signals were observed by the search which constrains the astrophysical rates of the IMBH mergers as a function of the component masses. In the most efficiently detected bin centered on 88 + 88 solar Mass , for non-spinning sources, the rate density upper limit is 0.13 per Mpc(exp 3) per Myr at the 90% confidence level
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