Validating the Use of Vignettes for Subjective Threshold Scales

Comparing self-assessed indicators of subjective outcomes such as health, work disability, political efficacy, job satisfaction, etc. across countries or socio-economic groups is often hampered by the fact that different groups use systematically different response scales. Anchoring vignettes have been introduced as an effective tool to correct for such differences. This paper develops an integrated framework in which objective measurements are used to validate the vignette-based corrections. The framework is applied to vignettes and objective and subjective self-assessments of drinking behavior by students in Ireland. Model comparisons using the Akaike information criterion favor a specification with response consistency and vignette corrected response scales. Put differently, vignette based corrections appear quite effective in bringing objective and subjective measures closer together.anchoring vignettes;reporting bias;hopit model

Preliminary design study of a quiet, high flow fan (QHF) stage

Concepts selected to reduce fan generated noise in a turbofan are presented. Near-sonic flow at the fan inlet to reduce upstream propagated noise and the use of long-chord vanes to reduce downstream noise is discussed. The near-sonic condition at the rotor inlet plane was achieved by designing for high specific mass flow and by maintaining the high flow at reduced power by variable stators and variable fan exhaust nozzle. The long-chord vanes reduce response to unsteady flow. The acoustic design showed that long-chord stators would significantly reduce turbofan source noise and that other stator design parameters have no appreciable effect on noise for the spacing and chord length of the turbofan design. Four rig flow paths studied in the aerodynamic preliminary design are discussed. Noise prediction results indicate that a turbofan powered aircraft would be under federal air regulations levels without any acoustic treatment

Cassiopeia A: dust factory revealed via submillimetre polarimetry

If Type-II supernovae - the evolutionary end points of short-lived, massive stars - produce a significant quantity of dust (>0.1 M_sun) then they can explain the rest-frame far-infrared emission seen in galaxies and quasars in the first Gyr of the Universe. Submillimetre observations of the Galactic supernova remnant, Cas A, provided the first observational evidence for the formation of significant quantities of dust in Type-II supernovae. In this paper we present new data which show that the submm emission from Cas A is polarised at a level significantly higher than that of its synchrotron emission. The orientation is consistent with that of the magnetic field in Cas A, implying that the polarised submm emission is associated with the remnant. No known mechanism would vary the synchrotron polarisation in this way and so we attribute the excess polarised submm flux to cold dust within the remnant, providing fresh evidence that cosmic dust can form rapidly. This is supported by the presence of both polarised and unpolarised dust emission in the north of the remnant, where there is no contamination from foreground molecular clouds. The inferred dust polarisation fraction is unprecedented (f_pol ~ 30%) which, coupled with the brief timescale available for grain alignment (<300 yr), suggests that supernova dust differs from that seen in other Galactic sources (where f_pol=2-7%), or that a highly efficient grain alignment process must operate in the environment of a supernova remnant.Comment: In press at MNRAS, 10 pages, print in colou

The negatively charged nitrogen-vacancy centre in diamond: the electronic solution

The negatively charged nitrogen-vacancy centre is a unique defect in diamond that possesses properties highly suited to many applications, including quantum information processing, quantum metrology, and biolabelling. Although the unique properties of the centre have been extensively documented and utilised, a detailed understanding of the physics of the centre has not yet been achieved. Indeed there persists a number of points of contention regarding the electronic structure of the centre, such as the ordering of the dark intermediate singlet states. Without a sound model of the centre's electronic structure, the understanding of the system's unique dynamical properties can not effectively progress. In this work, the molecular model of the defect centre is fully developed to provide a self consistent model of the complete electronic structure of the centre. The application of the model to describe the effects of electric, magnetic and strain interactions, as well as the variation of the centre's fine structure with temperature, provides an invaluable tool to those studying the centre and a means to design future empirical and ab initio studies of this important defect.Comment: 24 pages, 6 figures, 10 table

Lithium-to-calcium ratios in Modern, Cenozoic, and Paleozoic articulate brachiopod shells

Li/Ca ratios in modern brachiopod shells generally correlate inversely with growth temperature, ranging from ∼20 µmol/mol at 30°C to ∼50 µmol/mol at 0°C with no apparent interspecific offsets. Causes of the temperature effect on Li/Ca ratios are not yet understood. Cenozoic brachiopod Li/Ca ratios average ∼30 µmol/mol, similar to the average observed in modern brachiopods. Relatively constant Li/Ca ratios for Eocene to Pleistocene nonluminescent brachiopod shells, consistent with previous observations of Cenozoic planktonic foraminifera, support the conclusion of little variation in Cenozoic seawater Li/Ca. Nonluminescent portions of Permian and Carboniferous brachiopods have Li/Ca ratios substantially lower (generally <10 µmol/mol) than modern, Cenozoic, or Devonian samples. Mass balance considerations, constrained by δ18O of brachiopods, suggest that low Li concentrations in Permo-Carboniferous seawater could be the result of a lower flux of dissolved Li from the continents and/or a higher flux of Li from seawater to clastic marine sediments. Nonluminescent Devonian brachiopods from a single hand specimen have Li/Ca ratios around 70% of the modern average. These Li/Ca ratios can be explained by either somewhat higher temperature with constant seawater Li/Ca, somewhat lower seawater Li/Ca at constant temperature, or a combination of slightly elevated temperature and slightly lower seawater Li/Ca

Importance of the lipid-related pathways in the association between statins, mortality and cardiovascular disease risk : the multi-ethnic study of atherosclerosis

PURPOSE: Estimating how much of the impact of statins on coronary heart diseases (CHD), cardiovascular disease (CVD), and mortality risk is attributable to their effect on low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), and triglycerides. METHODS: A semi-parametric g-formula estimator together with data from the Multi-Ethnic Study of Atherosclerosis (a prospective multi-center cohort study) was utilized to perform a mediation analysis. A total of 5280 participants, men and women of various race/ethnicities from multiple sites across the United States, were considered in the current study. RESULTS: The adherence adjusted total relative risk reduction (RRR) estimate (95% confidence interval) of statins on CHD was 14% (-16%, 37%), and the indirect component through LDL was 23% (-4%, 58%). For CVD, the total RRR was 23% (2%, 40%), and the indirect component through LDL was 5% (-13%, 25%). The total RRR of mortality was 18% (-1%, 35%), and the indirect component through LDL was -4% (-17%, 12%). The estimated indirect components through HDL and triglycerides were close to zero with narrow confidence intervals for all 3 outcomes. CONCLUSIONS: The estimated effect of statins on mortality, CVD, and CHD appeared to be independent of their estimated effect on HDL and triglycerides. Our study provides evidence that the preventive effect of statins on CHD could be attributed in large part to their effect on LDL. Our g-formula estimator is a promising approach to elucidate pathways, even if it is hard to make firm conclusions for the LDL pathway on mortality and CV

Quasicrystalline nature of quasicrystal surfaces: A photoemission study

Differently prepared surfaces of quasicrystalline i-Al-Pd-Mn are analyzed using angle-resolved photoemission in the x-ray andultraviolet range of photon energies. Depending on the preparation, we find both surfaces with crystalline structure and metallic character, and surfaces with quasicrystalline structural fingerprints and a suppressed density of states at the Fermi level, compatible with a pseudogap