6,303 research outputs found

    Magnetic Miniband Structure and Quantum Oscillations in Lateral Semiconductor Superlattices

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    We present fully quantum-mechanical magnetotransport calculations for short-period lateral superlattices with one-dimensional electrostatic modulation. A non-perturbative treatment of both magnetic field and modulation potential proves to be necessary to reproduce novel quantum oscillations in the magnetoresistance found in recent experiments in the resistance component parallel to the modulation potential. In addition, we predict oscillations of opposite phase in the component perpendicular to the modulation not yet observed experimentally. We show that the new oscillations originate from the magnetic miniband structure in the regime of overlapping minibands.Comment: 6 pages with 4 figure

    Trends in rotator cuff repair rates and comorbidity burden among commercially insured patients younger than the age of 65 years, United States 2007-2016

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    BACKGROUND: Prior US studies have shown increasing rotator cuff repair rates through 2009. We hypothesize that rotator cuff repair rates are continuing to increase and the comorbidity profiles of patients are becoming more complex over time. METHODS: We identified rotator cuff repairs in a large US cohort of people 18-64 years of age with ≥1 year of commercial insurance coverage. Repair rate trends across time were standardized by age, sex, and geographic region. Procedures were categorized as inpatient vs. outpatient and as arthroscopic vs. open. Prevalent comorbidities were defined as 1 inpatient diagnosis claim or 2 outpatient diagnosis claims during the year before rotator cuff repair. General population comorbidity prevalence was determined based on a random 5% sample of the commercially insured population and compared with patients with rotator cuff repair using standardized morbidity ratios. RESULTS: From 2007 to 2016, 314,239 rotator cuff repairs were identified (165 repairs per 100,000 person-years). Rotator cuff repairs were performed more frequently in men, older people, and in the Midwest. Across time, cuff repair rates increased by 1.6% per year (95% confidence interval [CI] = +1.4%-1.7%) adjusting for demographics. The highest increases in repair rates were observed among patients aged 50-64 years (+2.0%, 95% CI = +1.8%-2.2%). Rotator cuff repairs were more frequently performed using an arthroscopic approach and in an outpatient setting in later calendar years. In 2016, 83% of rotator cuff repairs were arthroscopic procedures and 99% were performed as outpatient procedures. Comorbidity prevalence in rotator cuff repair patients increased across calendar time by 4.5% per year for hypertension (95% CI = +4.2%-4.7%), 2.3% per year for diabetes (+1.9%-2.7%), 0.9% per year for hypercholesterolemia (+0.3%-1.5%), 2.9% for congestive heart failure (+0.8%-4.9%), 4.2% for peripheral vascular disease (+2.4%-6.0%), and 4.2% for chronic pulmonary disease (+3.6%-4.8%). Comorbidity prevalence in repair patients was higher than prevalence in the general population, and prevalence relative to the general population was most heightened during later calendar years. For example, hypertension prevalence was 1.58 times higher in repair patients than the general population in 2007 (95% CI = 1.53-1.62), and 2.06 times higher in 2016 (95% CI = 2.02-2.11). CONCLUSION: Rotator cuff repair is becoming more frequent in the US commercially insured population, particularly in those 50-64 years of age. More rotator cuff repairs are being performed using an arthroscopic approach and in an outpatient setting. Over time, the comorbidity profile of patients undergoing rotator cuff repair is becoming more complex with greater prevalence of numerous conditions, including hypertension, peripheral vascular disease, and chronic pulmonary disease

    The hearing of fitness to practice cases by the General Medical Council: Current trends and future research agendas

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    Over the last three decades a risk-based model of medical regulation has emerged in the United Kingdom. To promote a risk-averse operational culture of transparency and professional accountability the regulatory state has intervened in medical governance and introduced best-evidenced practice frameworks, audit and performance appraisal, Against this background the paper analyses descriptive statistical data pertaining to the General Medical Council’s management of the process by which fitness to practice complaints against doctors are dealt with from initial receipt through to subsequent investigative and adjudication stages. Statistical trends are outlined regarding complaint data in relation to a doctor’s gender and race and ethnicity. The data shows that there has been an increase in rehabilitative and/or punitive action against doctors. In light of its findings the paper considers what the long-term consequences may be, for both patients and doctors, of the increasing use of risk-averse administrative systems to reform medical regulation and ensure professional accountability

    A geoarchaeological perspective on the challenges and trajectories of Mississippi Delta communities

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    Recent geochronology of the Mississippi Delta of coastal Louisiana, USA, provides a high-resolution record of land growth that facilitates the study of ancient settlement patterns in relation to delta evolution. We use stratigraphy and optically stimulated luminescence (OSL) dating to show that two Late Holocene earthen mounds were constructed several hundred years after the land emerged from open water. This multi-century pause allowed natural processes of overbank and crevasse splay deposition to elevate the land surface, reduce flood risk, and foster desirable environmental conditions prior to human occupation. These results are applied to obtain new age constraints for a large number of at-risk or lost archaeological sites with little-to-no absolute chronology. We use our findings to comment on prehistoric, contemporary, and future human-landscape interactions in the Mississippi Delta and other deltaic environments.</p

    Pilot In-Trail Procedure Validation Simulation Study

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    A Human-In-The-Loop experiment was conducted at the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) to investigate the viability of the In-Trail Procedure (ITP) concept from a flight crew perspective, by placing participating airline pilots in a simulated oceanic flight environment. The test subject pilots used new onboard avionics equipment that provided improved information about nearby traffic and enabled them, when specific criteria were met, to request an ITP flight level change referencing one or two nearby aircraft that might otherwise block the flight level change. The subject pilots subjective assessments of ITP validity and acceptability were measured via questionnaires and discussions, and their objective performance in appropriately selecting, requesting, and performing ITP flight level changes was evaluated for each simulated flight scenario. Objective performance and subjective workload assessment data from the experiment s test conditions were analyzed for statistical and operational significance and are reported in the paper. Based on these results, suggestions are made to further improve the ITP
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