368 research outputs found

    Towards a new definition of the typical day in the alcohol use disorder identification test-consumption

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    Introduction: The standard screening instrument for alcohol problems in the current primary care, the Alcohol Use Disorder Identification Test-Consumption (AUDIT-C), contains a question about alcohol consumption "on a typical day." Since this is a term that leaves room for multiple interpretations and the differences between alcohol consumption on weekends and weekdays are not taken into account, this study examines whether the latter distinction improves the prediction validity of the screening instrument.Methods: A subgroup of 852 participants of the Dutch version of Dry January ("NoThanks") 2022 got the annual "NoThanks" survey, including questions about their alcohol consumption on weekends and weekdays, and the original ten AUDIT questions. The full AUDIT was used as golden standard. Sensitivity, specificity, and receiver operating characteristic curves were calculated for the original and different versions of the AUDIT-C.Results: Of all participants, 67 percent were hazardous drinkers (AUDIT ≥8) and 27 percent were harmful drinkers (AUDIT ≥16). For the original AUDIT-C, the cut-off score with the most balanced combination of sensitivity and specificity for hazardous drinking in men was 7 and in women was 6. For harmful drinking, this was 8 and 7, respectively. Certain versions performed equally well as the original. For harmful drinkers, the highest area under the receiver operating characteristic curve (AUROC) was 0.814 and 0.866 for the original AUDIT-C, for men and women, respectively. Only for hazardous drinking men, the AUDIT-C with weekend day (AUROC = 0.887) performed slightly better than the original.Conclusion: Distinguishing weekend- and weekday alcohol consumption in the AUDIT-C does not lead to better predictions of problematic alcohol use. However, the distinction between weekends and weekdays provides more detailed information for healthcare professionals and can be used without having to compromise too much on validity

    Enhancement of the magnetic anisotropy of nanometer-sized Co clusters: influence of the surface and of the inter-particle interactions

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    We study the magnetic properties of spherical Co clusters with diameters between 0.8 nm and 5.4 nm (25 to 7500$ atoms) prepared by sequential sputtering of Co and Al2O3. The particle size distribution has been determined from the equilibrium susceptibility and magnetization data and it is compared to previous structural characterizations. The distribution of activation energies was independently obtained from a scaling plot of the ac susceptibility. Combining these two distributions we have accurately determined the effective anisotropy constant Keff. We find that Keff is enhanced with respect to the bulk value and that it is dominated by a strong anisotropy induced at the surface of the clusters. Interactions between the magnetic moments of adjacent layers are shown to increase the effective activation energy barrier for the reversal of the magnetic moments. Finally, this reversal is shown to proceed classically down to the lowest temperature investigated (1.8 K).Comment: 13 figures submitted to Phys. Rev.

    Field Measurements of Terrestrial and Martian Dust Devils

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    Surface-based measurements of terrestrial and martian dust devils/convective vortices provided from mobile and stationary platforms are discussed. Imaging of terrestrial dust devils has quantified their rotational and vertical wind speeds, translation speeds, dimensions, dust load, and frequency of occurrence. Imaging of martian dust devils has provided translation speeds and constraints on dimensions, but only limited constraints on vertical motion within a vortex. The longer mission durations on Mars afforded by long operating robotic landers and rovers have provided statistical quantification of vortex occurrence (time-of-sol, and recently seasonal) that has until recently not been a primary outcome of more temporally limited terrestrial dust devil measurement campaigns. Terrestrial measurement campaigns have included a more extensive range of measured vortex parameters (pressure, wind, morphology, etc.) than have martian opportunities, with electric field and direct measure of dust abundance not yet obtained on Mars. No martian robotic mission has yet provided contemporaneous high frequency wind and pressure measurements. Comparison of measured terrestrial and martian dust devil characteristics suggests that martian dust devils are larger and possess faster maximum rotational wind speeds, that the absolute magnitude of the pressure deficit within a terrestrial dust devil is an order of magnitude greater than a martian dust devil, and that the time-of-day variation in vortex frequency is similar. Recent terrestrial investigations have demonstrated the presence of diagnostic dust devil signals within seismic and infrasound measurements; an upcoming Mars robotic mission will obtain similar measurement types

    Gravitational radiation from gamma-ray bursts as observational opportunities for LIGO and VIRGO

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    Gamma-ray bursts are believed to originate in core-collapse of massive stars. This produces an active nucleus containing a rapidly rotating Kerr black hole surrounded by a uniformly magnetized torus represented by two counter-oriented current rings. We quantify black hole spin-interactions with the torus and charged particles along open magnetic flux-tubes subtended by the event horizon. A major output of Egw=4e53 erg is radiated in gravitational waves of frequency fgw=500 Hz by a quadrupole mass-moment in the torus. Consistent with GRB-SNe, we find (i) Ts=90s (tens of s, Kouveliotou et al. 1993), (ii) aspherical SNe of kinetic energy Esn=2e51 erg (2e51 erg in SN1998bw, Hoeflich et al. 1999) and (iii) GRB-energies Egamma=2e50 erg (3e50erg in Frail et al. 2001). GRB-SNe occur perhaps about once a year within D=100Mpc. Correlating LIGO/Virgo detectors enables searches for nearby events and their spectral closure density 6e-9 around 250Hz in the stochastic background radiation in gravitational waves. At current sensitivity, LIGO-Hanford may place an upper bound around 150MSolar in GRB030329. Detection of Egw thus provides a method for identifying Kerr black holes by calorimetry.Comment: to appear in PRD, 49
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