Estimates of prevalence, demographic characteristics and social factors among people with disabilities in the USA: a cross-survey comparison

Objective: A national priority for disability research in the USA is the standardised identification of people with disabilities in surveillance efforts. Mandated by federal statute, six dichotomous difficulty-focused questions were implemented in national surveys to identify people with disabilities. The aim of this study was to assess the prevalence, demographic characteristics and social factors among people with disabilities based on these six questions using multiple national surveys in the USA. Setting: American Community Survey (ACS), Current Population Survey Annual Social and Economic Supplement (CPS-ASEC), National Health Interview Survey (NHIS) and the Survey of Income and Program Participation (SIPP). Participants: Civilian, non-institutionalised US residents aged 18 and over from the 2009 to 2014 ACS, 2009 to 2014 CPS-ASEC, 2009 to 2014 NHIS and 2008 SIPP waves 3, 7 and 10. Primary and secondary outcome measures: Disability was assessed using six standardised questions asking people about hearing, vision, cognition, ambulatory, self-care and independent living disabilities. Social factors were assessed with questions asking people to report their education, employment status, family size, health and marital status, health insurance and income. Results: Risk ratios and demographic distributions for people with disabilities were consistent across survey. People with disabilities were at decreased risk of having college education, employment, families with three or more people, excellent or very good self-reported health and a spouse. People with disabilities were also consistently at greater risk of having health insurance and living below the poverty line. Estimates of disability prevalence varied between surveys from 2009 to 2014 (range 11.76%–17.08%). Conclusion: Replicating the existing literature, we found the estimation of disparities and inequity people with disabilities experience to be consistent across survey. Although there was a range of prevalence estimates, demographic factors for people with disabilities were consistent across surveys. Variations in prevalence estimates can be explained by survey context effects

Destiny: A Candidate Architecture for the Joint Dark Energy Mission

Destiny is a simple, direct, low cost mission to determine the properties of dark energy by obtaining a cosmologically deep supernova (SN) type Ia Hubble diagram. Operated at L2, its science instrument is a 1.65m space telescope, featuring a grism-fed near-infrared (NIR) (0.85-1.7micron) survey camera/spectrometer with a 0.12 square degree field of view. During its two-year primary mission, Destiny will detect, observe, and characterize ~3000 SN Ia events over the redshift interval 0.4<z<1.7 within a 3 square degree survey area. In conjunction with ongoing ground-based SN Ia surveys for z<0.8, Destiny mission data will be used to construct a high-precision Hubble diagram and thereby constrain the dark energy equation of state from a time when it was strongly matter-dominated to the present when dark energy dominates. The grism-images simultaneously provide broad-band photometry, redshifts, and SN classification, as well as time-resolved diagnostic data for investigating additional SN luminosity diagnostics. Destiny will be used in its third year as a high resolution, wide-field imager to conduct a multicolor NIR weak lensing (WL) survey covering 1000 square degrees. The large-scale mass power spectrum derived from weak lensing distortions of field galaxies as a function of redshift will provide independent and complementary constraints on the dark energy equation of state. The combination of SN and WL is much more powerful than either technique on its own. Used together, these surveys will have more than an order of magnitude greater sensitivity than will be provided by ongoing ground-based projects. The dark energy parameters, w_0 and w_a, will be measured to a precision of 0.05 and 0.2 respectively.Comment: Contains full color figure

Optical and other property changes of M-50 bearing steel surfaces for different lubricants and additive prior to scuffing

An ester lubricant base oil containing one or more standard additives to protect against wear, corrosion, and oxidation was used in an experimental ball/plate elastohydrodynamic contact under load and speed conditions such as to induce scuffing failure in short times. Both the ball and the plate were of identically treated M-50 steel. After various periods of operating time the wear track on the plate was examined with an interference microscope of plus or minus 30 A depth resolution and sometimes also with a scanning ellipsometer and an Auger spectrometer. The optically deduced surface profiles varied with wavelength, indicating the presence of surface coatings, which were confirmed by the other instruments. As scuffing was approached, a thin (approximately A) oxide layer and a carbide layer formed in the wear track in particular when tricresylphosphate antiwear additive was present in the lubricant. The rates of the formation of these layers and their reactivity toward dilute alcholic HCl depended strongly on the lubricant and additives. Based on these results suggestions for improved formulations and a test method for bearing reliability could be proposed

Surface topographical changes measured by phase-locked interferometry

An electronic optical laser interferometer capable of resolving depth differences of as low as 30 A and planar displacements of 6000 A was constructed to examine surface profiles of bearing surfaces without physical contact. Topological chemical reactivity was determined by applying a drop of dilute alcoholic hydrochloric acid and measuring the profile of the solid surface before and after application of this probe. Scuffed bearing surfaces reacted much faster than virgin ones but that bearing surfaces exposed to lubricants containing an organic chloride reacted much more slowly. The reactivity of stainless steel plates, heated in a nitrogen atmosphere to different temperatures, were examined later at ambient temperature. The change of surface contour as a result of the probe reaction followed Arrhenius-type relation with respect to heat treatment temperature. The contact area of the plate of a ball/plate sliding elastohydrodynamic contact run on trimethylopropane triheptanoate with or without additives was optically profiled periodically. As scuffing was approached, the change of profile within the contact region changed much more rapidly by the acid probe and assumed a constant high value after scuffing. A nonetching metallurgical phase was found in the scuff mark, which was apparently responsible for the high reactivity