1,404 research outputs found
Will Job Testing Harm Minority Workers?
Because minorities typically fare poorly on standardized tests, job testing is thought to pose an equity-efficiency trade-off: testing improves selection but reduces minority hiring. We develop a conceptual framework to assess when this tradeoff is likely to apply and evaluate the evidence for such a trade-off using data from a national retail firm whose 1,363 stores switched from informal to test-based worker screening over the course of on year. We document that testing yielded more productive hires at this firm -- raising median tenure by 10-plus percent. Consistent with prior research, minorities performed worse on the test. Yet, testing had no measurable impact on minority hiring, and productivity gains were uniformly large among minorities and non-minorities. These results suggest that job testing raised the precision of screening without introducing additional negative information about minority applicants, most plausibly because both the job test and the informal screen that preceded it were unbiased.
Trends in social inequalities for premature coronary heart disease mortality in Great Britain, 1994–2008: a time trend ecological study
OBJECTIVE: To compare trends in metrics of socioeconomic inequalities in premature coronary heart disease (CHD) mortality in Great Britain. DESIGN: Time trend ecological study with area-level deprivation as exposure. SETTING: Great Britain, 1994-2008. PARTICIPANTS: Men and women aged younger than 75 years. No lower age limit. INTERVENTIONS: None. MAIN OUTCOME MEASURES: CHD mortality rates. RESULTS: There has been a decrease in socioeconomic inequalities in CHD mortality in absolute terms but an increase in relative terms. CHD mortality rates in men aged younger than 75 years fell by 69 per 100 000 (95% CIs 64 to 74) in the least deprived quintile and by 92 per 100 000 (95% CI 86 to 98) in the most deprived quintile (p for trend: <0.001). Mortality rate ratios comparing the most deprived quintile to the least deprived quintile increased in women aged younger than 75 years from 1.77 (95% CI 1.68 to 1.86) to 2.32 (95% CI 2.14 to 2.52). There was a weak negative association between the average decline of relative rates and area deprivation. CONCLUSIONS: It could either be said that inequalities in premature mortality from CHD between affluent and deprived areas have widened or narrowed between 1994 and 2008 depending on the measurement technique. In the context of falling CHD mortality rates, narrowing of absolute inequalities is to be expected, but increases in relative inequalities are a cause for concern
Differences in coronary heart disease, stroke and cancer mortality rates between England, Wales, Scotland and Northern Ireland: the role of diet and nutrition
Introduction It is unclear how much of the geographical variation in coronary heart disease (CHD), stroke and cancer mortality rates within the UK is associated with diet. The aim of this study is to estimate how many deaths from CHD, stroke and cancer would be delayed or averted if Wales, Scotland and Northern Ireland adopted a diet equivalent in nutritional quality to the English diet. Methods Mortality data for CHD, stroke and 10 diet-related cancers for 2007-2009 were used to calculate the mortality gap (the difference between actual mortality and English mortality rates) for Wales, Scotland and Northern Ireland. Estimates of mean national consumption of 10 dietary factors were used as baseline and counterfactual inputs in a macrosimulation model (DIETRON). An uncertainty analysis was conducted using a Monte Carlo simulation with 5000 iterations. Results The mortality gap in the modelled scenario (achieving the English diet) was reduced by 81% (95% credible intervals: 62% to 108%) for Wales, 40% (33% to 51%) for Scotland and 81% (67% to 99%) for Northern Ireland, equating to approximately 3700 deaths delayed or averted annually. For CHD only, the mortality gap was reduced by 88% (69% to 118%) for Wales, 58% (47% to 72%) for Scotland, and 88% (70% to 111%) for Northern Ireland. Conclusion Improving the average diet in Wales, Scotland and Northern Ireland to a level already achieved in England could have a substantial impact on reducing geographical variations in chronic disease mortality rates in the UK. Much of the mortality gap between Scotland and England is explained by non-dietary risk factors
A Cross-Institutional Perspective of Pre Laboratory Activities in Undergraduate Chemistry
Pre-laboratory exercises may help reduce cognitive load in the laboratory, boost confidence, develop theoretical understanding and skills, and improve grades on assessment tasks. This study compared pre-laboratory activities at two institutions, Go8-1 and Go8-2, to evaluate which attributes of pre-laboratory activities were perceived by students to best prepare them for laboratory classes. Students were surveyed towards the end of their laboratory course, and were asked a series of Likert-style and open response questions. Factor analysis was used to construct three scales, incorporating items relating to performance and understanding, items relating to affective and personal laboratory experience, and items relating to requiring support with laboratory equipment. No difference between cohorts was observed between the two institutions regarding requiring support with equipment. While Go8-1 students rated performance and understanding more highly than Go8-2 students, the opposite result was observed for affective and personal factors. The factor analysis results and responses to the open response questions indicated that students felt most prepared for laboratory exercises when the pre-class activities touched upon all aspects of the laboratory class. It is recommended that quizzes and video be used in pre-laboratory activities, with these resources covering theory, aims, methods, calculations and data analysis
Haven or hell? : A perspective on the ecology of offshore oil and gas platforms
We acknowledge in-kind support from Net Zero Technology Centre and the University of Aberdeen through their partnership in the UK National Decommissioning Centre. Also E. Carr for graphical assistance.Peer reviewe
A Simulation Model Examining Boll Weevil Dispersal: Historical and Current Situations
A linear deterministic simulation model was developed to examine the historical rate of movement of the boll weevil, Anthonomus grandis grandis Boheman, across the southeastern United States. This manuscript addresses the hypotheses proposed during the initial invasion of the boll weevil that cotton production and prevailing winds were the primary factors regulating movement of this pest. A modification of the historical model was used to predict defensive strategies required to maintain boll weevil-free areas resulting from the current program effort
Ultrafast REMPI in benzene and the monohalobenzenes without the focal volume effect
We report on the photoionization and photofragmentation of benzene (C6H6) and of the monohalobenzenes C6H5–X (X = F, Cl, Br, I) under intense-field, single-molecule conditions. We focus 50-fs, 804-nm pulses from a Ti:sapphire laser source, and record ion mass spectra as a function of intensity in the range ~1013 W/cm2 to ~1015 W/cm2. We count ions that were created in the central, most intense part of the focal area; ions from other regions are rejected. For all targets, stable parent ions (C6H5X+) are observed. Our data is consistent with resonance-enhanced multiphoton ionization (REMPI) involving the neutral 1ππ* excited state (primarily a phenyl excitation): all of our plots of parent ion yield versus intensity display a kink when this excitation saturates. From the intensity dependence of the ion yield we infer that both the HOMO and the HOMO-1 contribute to ionization in C6H5F and C6H5Cl. The proportion of phenyl (C6H5) fragments in the mass spectra increases in the order X = F, Cl, Br, I. We ascribe these substituent-dependent observations to the different lifetimes of the C6H5X 1ππ* states. In X = I the heavy-atom effect leads to ultrafast intersystem crossing to a dissociative 3nσ* state. This breaks the C–I bond in an early stage of the ultrashort pulse, which explains the abundance of fragments that we find in the iodobenzene mass spectrum. For the lighter X = F, Cl, and Br this dissociation is much slower, which explains the lesser degree of fragmentation observed for these three molecules
Z-2 Threaded Insert Design and Testing
NASA's Z-2 prototype space suit contains several components fabricated from an advanced hybrid composite laminate consisting of IM10 carbon fiber and fiber glass. One requirement was to have removable, replaceable helicoil inserts to which other suit components would be fastened. An approach utilizing bonded in inserts with helicoils inside of them was implemented. During initial assembly, cracking sounds were heard followed by the lifting of one of the blind inserts out of its hole when the screws were torqued. A failure investigation was initiated to understand the mechanism of the failure. Ultimately, it was determined that the pre-tension caused by torqueing the fasteners is a much larger force than induced from the pressure loads of the suit which was not considered in the insert design. Bolt tension is determined by dividing the torque on the screw by a k value multiplied by the thread diameter of the bolt. The k value is a factor that accounts for friction in the system. A common value used for k for a non-lubricated screw is 0.2. The k value can go down by as much as 0.1 if the screw is lubricated which means for the same torque, a much larger tension could be placed on the bolt and insert. This paper summarizes the failure investigation that was performed to identify the root cause of the suit failure and details how the insert design was modified to resist a higher pull out tension
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Ambulatory measurement of knee motion and physical activity: preliminary evaluation of a smart activity monitor
BACKGROUND: There is currently a paucity of devices available for continuous, long-term monitoring of human joint motion. Non-invasive, inexpensive devices capable of recording human activity and joint motion have many applications for medical research. Such a device could be used to quantify range of motion outside the gait laboratory. The purpose of this study was to test the accuracy of the modified Intelligent Device for Energy Expenditure and Activity (IDEEA) in measuring knee flexion angles, to detect different physical activities, and to quantify how often healthy subjects use deep knee flexion in the ambulatory setting. METHODS: We compared Biomotion Laboratory (BML) "gold standard" data to simultaneous IDEEA measures of knee motion and gait, step up/down, and stair descent in 5 healthy subjects. In addition, we used a series of choreographed physical activities outside the BML to confirm the IDEEA's ability to accurately measure 7 commonly-performed physical activities. Subjects then continued data collection during ordinary activities outside the gait laboratory. RESULTS: Pooled correlations between the BML and IDEEA knee flexion angles were .97 +/- .03 for step up/down, .98 +/- .02 for stair descent, and .98 +/- .01 for gait. In the BML protocol, the IDEEA accurately identified gait, but was less accurate in identifying step up/down and stair descent. During sampling outside the BML, the IDEEA accurately detected walking, running, stair ascent, stair descent, standing, lying, and sitting. On average, subjects flexed their knees >120° for 0.17% of their data collection periods outside the BML. CONCLUSION: The modified IDEEA system is a useful clinical tool for evaluating knee motion and multiple physical activities in the ambulatory setting. These five healthy subjects rarely flexed their knees >120°
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