1,840 research outputs found
Acoustic vibration test detects intermittent electrical discontinuities
Nondestructive test method detects faulty electrical connections in inaccessible or hidden portions of electronic harness assemblies and connectors. Method employs readily available commercial equipment
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Stronger instruments and refined covariate balance in an observational study of the effectiveness of prompt admission to intensive care units
Instrumental variable methods, subject to appropriate identification assumptions, enable consistent estimation of causal effects in the presence of unobserved confounding. Near–far matching has been proposed as one analytic method to improve inference by strengthening the effect of the instrument on the exposure and balancing observable characteristics between groups of subjects with low and high values of the instrument. However, in settings with hierarchical data (e.g. patients nested within hospitals), or where several covariate interactions must be balanced, conventional near–far matching algorithms may fail to achieve the requisite covariate balance. We develop a new matching algorithm, that combines near–far matching with refined covariate balance, to balance large numbers of nominal covariates while also strengthening the instrumental variable. This extension of near–far matching is motivated by a case-study that aims to identify the causal effect of prompt admission to an intensive care unit on 7-day and 28-day mortality
The Effect of Exposure Duration on Perceived Similarity in Simultaneous Lineups
This item is only available electronically.Quantifying reliable and accurate eyewitness identification procedures which avoid wrongful convictions and give confidence to justice systems as to the accuracy of suspect guilt continues to be an area of intense research. Defining the parameters of a 'fair lineup' is central to this endeavour. Measures of similarity between lineup members have been key variables used to accurately describe what is and isn't a 'fair lineup'. To date little research has been done on how the perception of similarity may vary across groups and conditions, particularly as a result of memory encoding strength. This study aimed to understand how exposure time, a key variable for altering the encoding strength of a face, in the context of simultaneous lineups, may alter perceived similarity. Results showed that the observed data fit the Unequal Variance Signal Detection (UVSD) model well, however the predicted increases in discriminability with longer exposure duration and higher lineup similarity were not measured. Similarly no significant changes in perceived similarity were found between any of the conditions. Given observed differences in Hit (CID) and False Alarm (FA) rates between low and high similarity lineups this result suggests that judgements of perceived similarity between faces in a line up are unrelated to participants face familiarity judgements. This supports the independent observations assumption within the maximum likelihood method and indicates that overall a priori categorical classifications of lineups as wholly low or high in similarity are less important to discriminability than participants judgements about each faces familiarity to the memory of the target. This finding has implications for future research into 'fair lineup' design and measurement.Thesis (B.PsychSc(Hons)) -- University of Adelaide, School of Psychology, 201
Double trouble: the impact of multimorbidity and deprivation on preference-weighted health related quality of life - a cross sectional analysis of the Scottish Health Survey
<b>Objective</b> To investigate the association between multimorbidity and Preference_Weighted Health Related Quality of Life (PW_HRQoL), a score that combines physical and mental functioning, and how this varies by socioeconomic deprivation and age.<p></p>
<b>Design</b> The Scottish Health Survey (SHeS) is a cross-sectional representative survey of the general population which included the SF-12, a survey of HRQoL, for individuals 20 years and over.<p></p>
<b>Methods</b> For 7,054 participants we generated PW_HRQoL scores by running SF-12 responses through the SF-6D algorithm. The resulting scores ranged from 0.29 (worst health) to 1 (perfect health). Using ordinary least squares, we first investigated associations between scores and increasing counts of longstanding conditions, and then repeated for multimorbidity (2+ conditions). Estimates were made for the general population and quintiles of socioeconomic deprivation. For multimorbidity, the analyses were repeated stratifying the population by age group (20--44, 45--64, 65+).<p></p>
<b>Results</b> 45% of participants reported a longstanding condition and 18% reported multimorbidity. The presence of 1, 2, or 3+ longstanding conditions were associated with average reductions in PW_HRQoL scores of 0.081, 0.151 and 0.212 respectively. Reduction in scores associated with multimorbidity was 33% greater in the most deprived quintile compared to the least deprived quintile, with the biggest difference (80%) in the 20--44 age groups. There were no significant gender differences.<p></p>
<b>Conclusions</b> PW_HRQoL decreases markedly with multimorbidity, and is exacerbated by higher deprivation and younger age. There is a need to prioritise interventions to improve the HRQoL for (especially younger) adults with multimorbidity in deprived areas
Idiopathic hypoparathyroidism
Idiopathic hypoparathyroidism is a rare disease. Drake, Albright, Baur and Castleman 3 fully described it in 1939. Only 50 or 60 proven cases (de Mowbray,2 1953) have been reported in the literature. As far as we know the following is the first reported case in an African
How long is a hillslope?
Hillslope length is a fundamental attribute of landscapes, intrinsically linked to drainage density, landslide hazard, biogeochemical cycling and hillslope sediment transport. Existing methods to estimate catchment average hillslope lengths include inversion of drainage density or identification of a break in slope–area scaling, where the hillslope domain transitions into the fluvial domain. Here we implement a technique which models flow from point sources on hilltops across pixels in a digital elevation model (DEM), based on flow directions calculated using pixel aspect, until reaching the channel network, defined using recently developed channel extraction algorithms. Through comparisons between these measurement techniques, we show that estimating hillslope length from plots of topographic slope versus drainage area, or by inverting measures of drainage density, systematically underestimates hillslope length. In addition, hillslope lengths estimated by slope–area scaling breaks show large variations between catchments of similar morphology and area. We then use hillslope length–relief structure of landscapes to explore nature of sediment flux operating on a landscape. Distinct topographic forms are predicted for end-member sediment flux laws which constrain sediment transport on hillslopes as being linearly or nonlinearly dependent on hillslope gradient. Because our method extracts hillslope profiles originating from every ridgetop pixel in a DEM, we show that the resulting population of hillslope length–relief measurements can be used to differentiate between linear and nonlinear sediment transport laws in soil mantled landscapes. We find that across a broad range of sites across the continental United States, topography is consistent with a sediment flux law in which transport is nonlinearly proportional to topographic gradient
A comparison of alternative strategies for choosing control populations in observational studies.
Various approaches have been used to select control groups in observational studies: (1) from within the intervention area; (2) from a convenience sample, or randomly chosen areas; (3) from areas matched on area-level characteristics; and (4) nationally. The consequences of the decision are rarely assessed but, as we show, it can have complex impacts on confounding at both the area and individual levels. We began by reanalyzing data collected for an evaluation of a rapid response service on rates of unplanned hospital admission. Balance on observed individual-level variables was better with external than local controls, after matching. Further, when important prognostic variables were omitted from the matching algorithm, imbalances on those variables were also minimized using external controls. Treatment effects varied markedly depending on the choice of control area, but in the case study the variation was minimal after adjusting for the characteristics of areas. We used simulations to assess relative bias and means-squared error, as this could not be done in the case study. A particular feature of the simulations was unexplained variation in the outcome between areas. We found that the likely impact of unexplained variation for hospital admissions dwarfed the benefits of better balance on individual-level variables, leading us to prefer local controls in this instance. In other scenarios, in which there was less unexplained variation in the outcome between areas, bias and mean-squared error were optimized using external controls. We identify some general considerations relevant to the choice of control population in observational studies
The Mechanisms of Moral Disengagement in George W. Bush’s ‘War on Terrorism’ Rhetoric.
Despite considerable literature on the Bush administration’s war on terrorism rhetoric, little attention has been paid to its discourse of moral disengagement, leaving an important and still relevant gap that this paper aims to address. Rather than approaching this gap in terms of an archival historical analysis that is disconnected from the present, it proposes an exploratory revisit of the rhetoric that the benefits of hindsight might enrich and, we argue, aid in understanding connections to the current post-invasion turmoil and the gradual ISIS takeover. Having subjected nineteen presidential speeches to qualitative content analysis, we identified a number of moral disengagement mechanisms: moral justification, advantageous comparisons, and attribution of blame, dehumanisation of the enemy, the use of sanitizing language, diffusion of responsibility and minimization of harm. We also identified novel themes relating to American excellence/patriotism, religious ideals and fear- arousing appeals, offering original contributions to the existing literature and advancing our understanding of dynamic, real-world, and highest stakes moral disengagement whose parallels can be identified in today’s political discourses. The detailed analysis unveils the apparent paradox of propagating moral disengagement through a thread of arguments that interweave diversity with uniformity, complexity with simplicity, in effect alerting the reader to the processes of moral desensitisation that the past, current and future “warmongering” political discourses may often rely upon
Radio Planetary Nebulae in the Small Magellanic Cloud
We present ten new radio continuum (RC) detections at catalogued planetary
nebula (PN) positions in the Small Magellanic Cloud (SMC): SMPS6, LIN 41, LIN
142, SMP S13, SMP S14, SMP S16, J18, SMP S18, SMP S19 and SMP S22.
Additionally, six SMC radio PNe previously detected, LIN 45, SMP S11, SMPS17,
LIN321, LIN339 and SMPS24 are also investigated (re-observed) here making up a
population of 16 radio detections of catalogued PNe in the SMC. These 16 radio
detections represent ~15 % of the total catalogued PN population in the SMC. We
show that six of these objects have characteristics that suggest that they are
PN mimics: LIN 41, LIN 45, SMP S11, LIN 142, LIN 321 and LIN 339. We also
present our results for the surface brightness - PN radius relation
({\Sigma}-D) of the SMC radio PN population. These are consistent with previous
SMC and LMC PN measurements of the ({\Sigma}-D) relation.Comment: Accepted for publication in Astrophysics and Space Scienc
Estimating causal effects : considering three alternatives to difference-in-differences estimation
Difference-in-differences (DiD) estimators provide unbiased treatment effect estimates when, in the absence of treatment, the average outcomes for the treated and control groups would have followed parallel trends over time. This assumption is implausible in many settings. An alternative assumption is that the potential outcomes are independent of treatment status, conditional on past outcomes. This paper considers three methods that share this assumption: the synthetic control method, a lagged dependent variable (LDV) regression approach, and matching on past outcomes. Our motivating empirical study is an evaluation of a hospital pay-for-performance scheme in England, the best practice tariffs programme. The conclusions of the original DiD analysis are sensitive to the choice of approach. We conduct a Monte Carlo simulation study that investigates these methods’ performance. While DiD produces unbiased estimates when the parallel trends assumption holds, the alternative approaches provide less biased estimates of treatment effects when it is violated. In these cases, the LDV approach produces the most efficient and least biased estimates
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