22,287 research outputs found
Upper Limits from Counting Experiments with Multiple Pipelines
In counting experiments, one can set an upper limit on the rate of a Poisson
process based on a count of the number of events observed due to the process.
In some experiments, one makes several counts of the number of events, using
different instruments, different event detection algorithms, or observations
over multiple time intervals. We demonstrate how to generalize the classical
frequentist upper limit calculation to the case where multiple counts of events
are made over one or more time intervals using several (not necessarily
independent) procedures. We show how different choices of the rank ordering of
possible outcomes in the space of counts correspond to applying different
levels of significance to the various measurements. We propose an ordering that
is matched to the sensitivity of the different measurement procedures and show
that in typical cases it gives stronger upper limits than other choices. As an
example, we show how this method can be applied to searches for
gravitational-wave bursts, where multiple burst-detection algorithms analyse
the same data set, and demonstrate how a single combined upper limit can be set
on the gravitational-wave burst rate.Comment: 26 pages (CQG style), 8 figures. Added study of robustness of limits
Thermodynamic energy exchange in a moving plate capacitor
In this paper we describe an apparent paradox concerning a moving plate capacitor driven by thermal noise from a resistor. The plates are attracted together, but a demon restores the plates of the capacitor to their original position when the voltage across the capacitor is small-hence only small forces are present for the demon to work against. The demon has to work harder than this to avoid the situation of perpetual motion, but the open question is how? This is unsolved, however we explore the concept of a moving plate capacitor by examining the case where it is still excited by thermal noise, but where the restoring force on the capacitor plates is provided by a simple spring rather than some unknown demon. We display simulation results with interesting behavior, particularly where the capacitor plates collide with each other. (c) 2001 American Institute of Physics.B. R. Davis, D. Abbott, and J. M. R. Parrond
Guidance, flight mechanics and trajectory optimization. Volume 2 - Observation theory and sensors
Observation theory and sensors applicable to navigation of boost and space vehicle
Searches for Gravitational Waves from Binary Neutron Stars: A Review
A new generation of observatories is looking for gravitational waves. These
waves, emitted by highly relativistic systems, will open a new window for ob-
servation of the cosmos when they are detected. Among the most promising
sources of gravitational waves for these observatories are compact binaries in
the final min- utes before coalescence. In this article, we review in brief
interferometric searches for gravitational waves emitted by neutron star
binaries, including the theory, instru- mentation and methods. No detections
have been made to date. However, the best direct observational limits on
coalescence rates have been set, and instrumentation and analysis methods
continue to be refined toward the ultimate goal of defining the new field of
gravitational wave astronomy.Comment: 30 pages, 5 Figures, to appear in "Short-Period Binary Stars:
Observations, Analyses, and Results", Ed.s Eugene F. Milone, Denis A. Leahy,
David W. Hobil
Low-speed wind-tunnel investigation of the aerodynamic and acoustic performance of a translating grid choked flow inlet
The aerodynamic and acoustic performance of a translating grid choked-flow inlet was determined in a low-speed wind tunnel at free-stream velocities of 24, 32, and 45 m/sec and incidence angles of 0, 10, 20, 30, 35, 40, 45, and 50 deg. The inlet was sized to fit a 13.97- centimeter-diameter fan with a design weight flow of 2.49 kg/sec. Measurements were made to determine inlet total pressure recovery, flow distortion, and sound pressure level for both choked and unchoked geometries over a range of inlet weight flows. For the unchoked geometry, inlet total pressure recovery ranged from 0.983 to 0.989 at incidence angles less than 40 deg. At 40 deg incidence angle, inlet cowl separation was encountered which resulted in lower values of pressure recovery and higher levels of fan broadband noise. For the choked geometry, increasing total pressure losses occurred with increasing inlet weight flow that prevented the inlet from reaching full choked conditions with the particular fan used. These losses were attributed to the high Mach number drag rise characteristics of airfoil grid. At maximum attainable inlet weight flow, the total pressure recovery at static conditions was 0.935. The fan blade passing frequency and other fan generated pure tones were eliminated from the noise spectrum, but the broadband level was increased
Evolutionary importance of translation elongation factor eEF1A variant switching:eEF1A1 down-regulation in muscle is conserved in Xenopus but is controlled at a post-transcriptional level
Effects of the R-parity violation in the minimal supersymmetric standard model on dilepton pair production at the CERN LHC
We investigate in detail the effects of the R-parity lepton number violation
in the minimal supersymmetric standard model (MSSM) on the parent process at the CERN Large Hadron Collider (LHC). The numerical
comparisons between the contributions of the R-parity violating effects to the
parent process via the Drell-Yan subprocess and the gluon-gluon fusion are
made. We find that the R-violating effects on pair production at the
LHC could be significant. The results show that the cross section of the pair productions via gluon-gluon collision at the LHC can be of the order
of fb, and this subprocess maybe competitive with the production
mechanism via the Drell-Yan subprocess. We give also quantitatively the
analysis of the effects from both the mass of sneutrino and coupling strength
of the R-parity violating interactions.Comment: 18 pages, 10 figures, accepted by Phys. Rev.
Recent results on the search for continuous sources with LIGO and GEO600
An overview of the searches for continuous gravitational wave signals in LIGO
and GEO 600 performed on different recent science runs and results are
presented. This includes both searching for gravitational waves from known
pulsars as well as blind searches over a wide parameter space.Comment: TAUP2005 Proceedings to be published in Journal of Physics:
Conference Serie
Proposed method for searches of gravitational waves from PKS 2155-304 and other blazar flares
We propose to search for gravitational waves from PKS 2155-304 as well as
other blazars. PKS 2155-304 emitted a long duration energetic flare in July
2006, with total isotropic equivalent energy released in TeV gamma rays of
approximately ergs. Any possible gravitational wave signals
associated with this outburst should be seen by gravitational wave detectors at
the same time as the electromagnetic signal. During this flare, the two LIGO
interferometers at Hanford and the GEO detector were in operation and
collecting data. For this search we will use the data from multiple
gravitational wave detectors. The method we use for this purpose is a coherent
network analysis algorithm and is called {\tt RIDGE}. To estimate the
sensitivity of the search, we perform numerical simulations. The sensitivity to
estimated gravitational wave energy at the source is about
ergs for a detection probability of 20%. For this search, an end-to-end
analysis pipeline has been developed, which takes into account the motion of
the source across the sky.Comment: 10 pages, 7 figures. Contribution to 12th Gravitational Wave Data
Analysis Workshop. Submitted to Classical and Quantum Gravity. Changes in
response to referee comment
International Committee on Mental Health in Cystic Fibrosis: Cystic Fibrosis Foundation and European Cystic Fibrosis Society consensus statements for screening and treating depression and anxiety
Studies measuring psychological distress in individuals with cystic fibrosis (CF) have found high rates of both depression and anxiety. Psychological symptoms in both individuals with CF and parent caregivers have been associated with decreased lung function, lower body mass index, worse adherence, worse health-related quality of life, more frequent hospitalisations and increased healthcare costs. To identify and treat depression and anxiety in CF, the CF Foundation and the European CF Society invited a panel of experts, including physicians, psychologists, psychiatrists, nurses, social workers, a pharmacist, parents and an individual with CF, to develop consensus recommendations for clinical care. Over 18 months, this 22-member committee was divided into four workgroups: Screening; Psychological Interventions; Pharmacological Treatments and
Implementation and Future Research, and used the Population, Intervention, Comparison, Outcome methodology to develop questions for literature search and review. Searches were conducted in PubMed, PsychINFO, ScienceDirect, Google Scholar, Psychiatry
online and ABDATA by a methodologist at Dartmouth. The committee reviewed 344 articles, drafted statements and set an 80% acceptance for each recommendation statement as a consensus threshold prior to an anonymous voting process. Fifteen guideline recommendation statements for screening and treatment of depression and anxiety in individuals with CF and parent caregivers were finalised by vote. As these recommendations are implemented in CF centres internationally, the process of dissemination, implementation and resource provision should be closely monitored to assess barriers and concerns, validity and use
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