239 research outputs found
Sensitivity curves for spaceborne gravitational wave interferometers
To determine whether particular sources of gravitational radiation will be
detectable by a specific gravitational wave detector, it is necessary to know
the sensitivity limits of the instrument. These instrumental sensitivities are
often depicted (after averaging over source position and polarization) by
graphing the minimal values of the gravitational wave amplitude detectable by
the instrument versus the frequency of the gravitational wave. This paper
describes in detail how to compute such a sensitivity curve given a set of
specifications for a spaceborne laser interferometer gravitational wave
observatory. Minor errors in the prior literature are corrected, and the first
(mostly) analytic calculation of the gravitational wave transfer function is
presented. Example sensitivity curve calculations are presented for the
proposed LISA interferometer. We find that previous treatments of LISA have
underestimated its sensitivity by a factor of .Comment: 27 pages + 5 figures, REVTeX, accepted for publication in Phys Rev D;
Update reflects referees comments, figure 3 clarified, figure 5 corrected for
LISA baselin
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The Effect of Systematic Clinical Interventions with Cigarette Smokers on Quit Status and the Rates of Smoking-Related Primary Care Office Visits
Background: The United States Public Health Service (USPHS) Guideline for Treating Tobacco Use and Dependence includes ten key recommendations regarding the identification and the treatment of tobacco users seen in all health care settings. To our knowledge, the impact of system-wide brief interventions with cigarette smokers on smoking prevalence and health care utilization has not been examined using patient population-based data. Methods and Findings Data on clinical interventions with cigarette smokers were examined for primary care office visits of 104,639 patients at 17 Harvard Vanguard Medical Associates (HVMA) sites. An operational definition of “systems change” was developed. It included thresholds for intervention frequency and sustainability. Twelve sites met the criteria. Five did not. Decreases in self-reported smoking prevalence were 40% greater at sites that achieved systems change (13.6% vs. 9.7%, p<.01). On average, the likelihood of quitting increased by 2.6% (p<0.05, 95% CI: 0.1%–4.6%) per occurrence of brief intervention. For patients with a recent history of current smoking whose home site experienced systems change, the likelihood of an office visit for smoking-related diagnoses decreased by 4.3% on an annualized basis after systems change occurred (p<0.05, 95% CI: 0.5%–8.1%). There was no change in the likelihood of an office visit for smoking-related diagnoses following systems change among non-smokers. Conclusions: The clinical practice data from HVMA suggest that a systems approach can lead to significant reductions in smoking prevalence and the rate of office visits for smoking-related diseases. Most comprehensive tobacco intervention strategies focus on the provider or the tobacco user, but these results argue that health systems should be included as an integral component of a comprehensive tobacco intervention strategy. The HVMA results also give us an indication of the potential health impacts when meaningful use core tobacco measures are widely adopted
On the behaviour of Brauer -dimensions under finitely-generated field extensions
The present paper shows that if or , where is the set of prime numbers, then there exist characteristic fields , of Brauer dimension Brd and
infinite absolute Brauer -dimensions abrd, for all not dividing . This ensures that Brd, , for every finitely-generated transcendental
extension . We also prove that each sequence , , satisfying the conditions and , equals the sequence abrd, , for a field of characteristic zero.Comment: LaTeX, 14 pages: published in Journal of Algebra {\bf 428} (2015),
190-204; the abstract in the Metadata updated to fit the one of the pape
Competitive Equilibrium in the Random Assignment Problem
This paper studies the problem of random assignment with fractional endowments. In the random assignment problem, a number of objects has to be assigned to a number of agents. Though the objects are indivisible, an assignment can be probabilistic: it can give an agent some probability of getting an object. Fractional endowments complicate the matter because the assignment has to make an agent weakly better off than his endowment. I first formulate an exchange economy that resembles the random assignment problem and prove the existence of competitive equilibrium in this economy. I then propose a pseudo-market mechanism for the random assignment problem that is based on the competitive equilibrium. This mechanism is individually rational, Pareto Optimal and justified envy-free but not incentive compatible
The Bowen–Conradi syndrome protein Nep1 (Emg1) has a dual role in eukaryotic ribosome biogenesis, as an essential assembly factor and in the methylation of Ψ1191 in yeast 18S rRNA
The Nep1 (Emg1) SPOUT-class methyltransferase is an essential ribosome assembly factor and the human Bowen–Conradi syndrome (BCS) is caused by a specific Nep1D86G mutation. We recently showed in vitro that Methanocaldococcus jannaschii Nep1 is a sequence-specific pseudouridine-N1-methyltransferase. Here, we show that in yeast the in vivo target site for Nep1-catalyzed methylation is located within loop 35 of the 18S rRNA that contains the unique hypermodification of U1191 to 1-methyl-3-(3-amino-3-carboxypropyl)-pseudouri-dine (m1acp3Ψ). Specific 14C-methionine labelling of 18S rRNA in yeast mutants showed that Nep1 is not required for acp-modification but suggested a function in Ψ1191 methylation. ESI MS analysis of acp-modified Ψ-nucleosides in a Δnep1-mutant showed that Nep1 catalyzes the Ψ1191 methylation in vivo. Remarkably, the restored growth of a nep1-1ts mutant upon addition of S-adenosylmethionine was even observed after preventing U1191 methylation in a Δsnr35 mutant. This strongly suggests a dual Nep1 function, as Ψ1191-methyltransferase and ribosome assembly factor. Interestingly, the Nep1 methyltransferase activity is not affected upon introduction of the BCS mutation. Instead, the mutated protein shows enhanced dimerization propensity and increased affinity for its RNA-target in vitro. Furthermore, the BCS mutation prevents nucleolar accumulation of Nep1, which could be the reason for reduced growth in yeast and the Bowen-Conradi syndrome
Sensitivity of the Advanced LIGO detectors at the beginning of gravitational wave astronomy
The Laser Interferometer Gravitational Wave Observatory (LIGO) consists of two widely separated 4 km laser interferometers designed to detect gravitational waves from distant astrophysical sources in the frequency range from 10 Hz to 10 kHz. The first observation run of the Advanced LIGO detectors started in September 2015 and ended in January 2016. A strain sensitivity of better than 10−23/Hz−−−√ was achieved around 100 Hz. Understanding both the fundamental and the technical noise sources was critical for increasing the astrophysical strain sensitivity. The average distance at which coalescing binary black hole systems with individual masses of 30 M⊙ could be detected above a signal-to-noise ratio (SNR) of 8 was 1.3 Gpc, and the range for binary neutron star inspirals was about 75 Mpc. With respect to the initial detectors, the observable volume of the Universe increased by a factor 69 and 43, respectively. These improvements helped Advanced LIGO to detect the gravitational wave signal from the binary black hole coalescence, known as GW150914
Search for post-merger gravitational waves from the remnant of the binary neutron star merger GW170817
In Advanced LIGO, detection and astrophysical source parameter estimation of the binary black hole merger GW150914 requires a calibrated estimate of the gravitational-wave strain sensed by the detectors. Producing an estimate from each detector's differential arm length control loop readout signals requires applying time domain filters, which are designed from a frequency domain model of the detector's gravitational-wave response. The gravitational-wave response model is determined by the detector's opto-mechanical response and the properties of its feedback control system. The measurements used to validate the model and characterize its uncertainty are derived primarily from a dedicated photon radiation pressure actuator, with cross-checks provided by optical and radio frequency references. We describe how the gravitational-wave readout signal is calibrated into equivalent gravitational-wave-induced strain and how the statistical uncertainties and systematic errors are assessed. Detector data collected over 38 calendar days, from September 12 to October 20, 2015, contain the event GW150914 and approximately 16 of coincident data used to estimate the event false alarm probability. The calibration uncertainty is less than 10% in magnitude and 10 degrees in phase across the relevant frequency band 20 Hz to 1 kHz
Evidence-based Kernels: Fundamental Units of Behavioral Influence
This paper describes evidence-based kernels, fundamental units of behavioral influence that appear to underlie effective prevention and treatment for children, adults, and families. A kernel is a behavior–influence procedure shown through experimental analysis to affect a specific behavior and that is indivisible in the sense that removing any of its components would render it inert. Existing evidence shows that a variety of kernels can influence behavior in context, and some evidence suggests that frequent use or sufficient use of some kernels may produce longer lasting behavioral shifts. The analysis of kernels could contribute to an empirically based theory of behavioral influence, augment existing prevention or treatment efforts, facilitate the dissemination of effective prevention and treatment practices, clarify the active ingredients in existing interventions, and contribute to efficiently developing interventions that are more effective. Kernels involve one or more of the following mechanisms of behavior influence: reinforcement, altering antecedents, changing verbal relational responding, or changing physiological states directly. The paper describes 52 of these kernels, and details practical, theoretical, and research implications, including calling for a national database of kernels that influence human behavior
Supplement: "Localization and broadband follow-up of the gravitational-wave transient GW150914" (2016, ApJL, 826, L13)
This Supplement provides supporting material for Abbott et al. (2016a). We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands
First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data
In Advanced LIGO, detection and astrophysical source parameter estimation of the binary black hole merger GW150914 requires a calibrated estimate of the gravitational-wave strain sensed by the detectors. Producing an estimate from each detector's differential arm length control loop readout signals requires applying time domain filters, which are designed from a frequency domain model of the detector's gravitational-wave response. The gravitational-wave response model is determined by the detector's opto-mechanical response and the properties of its feedback control system. The measurements used to validate the model and characterize its uncertainty are derived primarily from a dedicated photon radiation pressure actuator, with cross-checks provided by optical and radio frequency references. We describe how the gravitational-wave readout signal is calibrated into equivalent gravitational-wave-induced strain and how the statistical uncertainties and systematic errors are assessed. Detector data collected over 38 calendar days, from September 12 to October 20, 2015, contain the event GW150914 and approximately 16 of coincident data used to estimate the event false alarm probability. The calibration uncertainty is less than 10% in magnitude and 10 degrees in phase across the relevant frequency band 20 Hz to 1 kHz
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