2,667 research outputs found

    Individual-level contact limits phonological complexity: Evidence from bunched and retroflex /ɹ/

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    We compare the complexity of idiosyncratic sound patterns involving American English /ɹ/ with the relative simplicity of clear/dark /l/ allophony patterns found in English and other languages. For /ɹ/, we report an ultrasound-based articulatory study of 27 speakers of American English. Two speakers use only retroflex /ɹ/, 16 use only bunched /ɹ/, and nine use both /ɹ/ types, with idiosyncratic allophonic distributions. These allophony patterns are covert, because the difference between bunched and retroflex /ɹ/ is not readily perceived by listeners. We compare this typology of /ɹ/ allophony patterns to clear/dark /l/ allophony patterns in 17 languages. On the basis of the observed patterns, we show that individual-level /ɹ/ allophony and language-level /l/ allophony exhibit similar phonetic grounding, but that /ɹ/ allophony patterns are considerably more complex. The low complexity of language-level /l/ allophony patterns, which are more readily perceived by listeners, is argued to be the result of individual-level contact in the development of sound patterns. More generally, we argue that familiar phonological patterns (which are relatively simple and homogeneous within communities) may arise from individual-level articulatory patterns, which may be complex and speaker-specific, by a process of koineization. We conclude that two classic properties of phonological rules, phonetic naturalness and simplicity, arise from different sources.published_or_final_versio

    Randomized trials, generalizability, and meta-analysis: Graphical insights for binary outcomes

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    BACKGROUND: Randomized trials stochastically answer the question. "What would be the effect of treatment on outcome if one turned back the clock and switched treatments in the given population?" Generalizations to other subjects are reliable only if the particular trial is performed on a random sample of the target population. By considering an unobserved binary variable, we graphically investigate how randomized trials can also stochastically answer the question, "What would be the effect of treatment on outcome in a population with a possibly different distribution of an unobserved binary baseline variable that does not interact with treatment in its effect on outcome?" METHOD: For three different outcome measures, absolute difference (DIF), relative risk (RR), and odds ratio (OR), we constructed a modified BK-Plot under the assumption that treatment has the same effect on outcome if either all or no subjects had a given level of the unobserved binary variable. (A BK-Plot shows the effect of an unobserved binary covariate on a binary outcome in two treatment groups; it was originally developed to explain Simpsons's paradox.) RESULTS: For DIF and RR, but not OR, the BK-Plot shows that the estimated treatment effect is invariant to the fraction of subjects with an unobserved binary variable at a given level. CONCLUSION: The BK-Plot provides a simple method to understand generalizability in randomized trials. Meta-analyses of randomized trials with a binary outcome that are based on DIF or RR, but not OR, will avoid bias from an unobserved covariate that does not interact with treatment in its effect on outcome

    The Paired Availability Design for Historical Controls

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    BACKGROUND: Although a randomized trial represents the most rigorous method of evaluating a medical intervention, some interventions would be extremely difficult to evaluate using this study design. One alternative, an observational cohort study, can give biased results if it is not possible to adjust for all relevant risk factors. METHODS: A recently developed and less well-known alternative is the paired availability design for historical controls. The paired availability design requires at least 10 hospitals or medical centers in which there is a change in the availability of the medical intervention. The statistical analysis involves a weighted average of a simple "before" versus "after" comparison from each hospital or medical center that adjusts for the change in availability. RESULTS: We expanded requirements for the paired availability design to yield valid inference. (1) The hospitals or medical centers serve a stable population. (2) Other aspects of patient management remain constant over time. (3) Criteria for outcome evaluation are constant over time. (4) Patient preferences for the medical intervention are constant over time. (5) For hospitals where the intervention was available in the "before" group, a change in availability in the "after group" does not change the effect of the intervention on outcome. CONCLUSION: The paired availability design has promise for evaluating medical versus surgical interventions, in which it is difficult to recruit patients to a randomized trial

    Cyberbullying and eating disorder symptoms in US early adolescents

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    Objective: The objective of this study was to determine the association between cyberbullying and eating disorder symptoms in a national sample of 10–14-year-old early adolescents. / Method: We analyzed cross-sectional data from the Adolescent Brain Cognitive Development (ABCD) Study (Year 2, 2018–2020, N = 10,258/11,875, 49% female, 46% non-White). Data were collected using multi-stage probability sampling. Modified Poisson regression analyses examined the association between cyberbullying and self-reported eating disorder symptoms based on the Kiddie Schedule for Affective Disorders and Schizophrenia (KSADS-5). / Results: Cyberbullying victimization was associated with worry about weight gain (prevalence ratio [PR] 2.41, 95% confidence interval [CI] 1.48–3.91), self-worth tied to weight (PR 2.08, 95% CI 1.33–3.26), inappropriate compensatory behavior to prevent weight gain (PR 1.95, 95% CI 1.57–2.42), binge eating (PR 1.95, 95% CI 1.59–2.39), and distress with binge eating (PR 2.64, 95% CI 1.94–3.59), in models adjusting for potential confounders. Cyberbullying perpetration was associated with worry about weight gain (PR 3.52, 95% CI 1.19–10.37), self-worth tied to weight (PR 5.59, 95% CI 2.56–12.20), binge eating (PR 2.36, 95% CI 1.44–3.87), and distress with binge eating (PR 2.84, 95% CI 1.47–5.49). / Discussion: Cyberbullying victimization and perpetration in early adolescence are associated with eating disorder symptoms. Clinicians may consider assessing for cyberbullying and eating disorder symptoms in early adolescence and provide anticipatory guidance. / Public Significance Statement: Eating disorders often onset in adolescence and have among the highest mortality rates of any psychiatric disorder. In addition, cyberbullying has increased in prevalence among adolescents and significantly impacts mental health. In a national study of early adolescents, we found that cyberbullying victimization and perpetration are associated with eating disorder symptoms. Screening for and providing anticipatory guidance on cyberbullying and eating disorder symptoms in early adolescents may be warranted

    Neuroprotection in a Novel Mouse Model of Multiple Sclerosis

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    The authors acknowledge the support of the Barts and the London Charity, the Multiple Sclerosis Society of Great Britain and Northern Ireland, the National Multiple Sclerosis Society, USA, notably the National Centre for the Replacement, Refinement & Reduction of Animals in Research, and the Wellcome Trust (grant no. 092539 to ZA). The siRNA was provided by Quark Pharmaceuticals. The funders and Quark Pharmaceuticals had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

    Attosecond control of electrons emitted from a nanoscale metal tip

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    Attosecond science is based on steering of electrons with the electric field of well-controlled femtosecond laser pulses. It has led to, for example, the generation of XUV light pulses with a duration in the sub-100-attosecond regime, to the measurement of intra-molecular dynamics by diffraction of an electron taken from the molecule under scrutiny, and to novel ultrafast electron holography. All these effects have been observed with atoms or molecules in the gas phase. Although predicted to occur, a strong light-phase sensitivity of electrons liberated by few-cycle laser pulses from solids has hitherto been elusive. Here we show a carrier-envelope (C-E) phase-dependent current modulation of up to 100% recorded in spectra of electrons laser-emitted from a nanometric tungsten tip. Controlled by the C-E phase, electrons originate from either one or two sub-500as long instances within the 6-fs laser pulse, leading to the presence or absence of spectral interference. We also show that coherent elastic re-scattering of liberated electrons takes place at the metal surface. Due to field enhancement at the tip, a simple laser oscillator suffices to reach the required peak electric field strengths, allowing attosecond science experiments to be performed at the 100-Megahertz repetition rate level and rendering complex amplified laser systems dispensable. Practically, this work represents a simple, exquisitely sensitive C-E phase sensor device, which can be shrunk in volume down to ~ 1cm3. The results indicate that the above-mentioned novel attosecond science techniques developed with and for atoms and molecules can also be employed with solids. In particular, we foresee sub-femtosecond (sub-) nanometre probing of (collective) electron dynamics, such as plasmon polaritons, in solid-state systems ranging in size from mesoscopic solids via clusters to single protruding atoms.Comment: Final manuscript version submitted to Natur

    Investigating the origin of magnetic perturbations associated with the FIP Effect

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    Recently, magnetic oscillations were detected in the chromosphere of a large sunspot and found to be linked to the coronal locations where a first ionization potential (FIP) effect was observed. In an attempt to shed light on the possible excitation mechanisms of these localized waves, we further investigate the same data by focusing on the relation between the spatial distribution of the magnetic wave power and the overall field geometry and plasma parameters obtained from multi-height spectropolarimetric non-local thermodynamic equilibrium (NLTE) inversions of IBIS data. We find, in correspondence with the locations where the magnetic wave energy is observed at chromospheric heights, that the magnetic fields have smaller scale heights, meaning faster expansions of the field lines, which ultimately results in stronger vertical density stratification and wave steepening. In addition, the acoustic spectrum of the oscillations at the locations where magnetic perturbations are observed is broader than that observed at other locations, which suggests an additional forcing driver to the p-modes. Analysis of the photospheric oscillations in the sunspot surroundings also reveals a broader spectrum between the two opposite polarities of the active region (the leading spot and the trailing opposite polarity plage), and on the same side where magnetic perturbations are observed in the umbra. We suggest that strong photospheric perturbations between the two polarities are responsible for this broader spectrum of oscillations, with respect to the p-mode spectrum, resulting in locally excited acoustic waves that, after crossing the equipartition layer, located close to the umbra-penumbra boundary at photopheric heights, are converted into magnetic waves and steepen due to the strong density gradient

    Incorporating health care quality into health antitrust law

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    <p>Abstract</p> <p>Background</p> <p>Antitrust authorities treat price as a proxy for hospital quality since health care quality is difficult to observe. As the ability to measure quality improved, more research became necessary to investigate the relationship between hospital market power and patient outcomes. This paper examines the impact of hospital competition on the quality of care as measured by the risk-adjusted mortality rates with the hospital as the unit of analysis. The study separately examines the effect of competition on non-profit hospitals.</p> <p>Methods</p> <p>We use California Office of Statewide Health Planning and Development (OSHPD) data from 1997 through 2002. Empirical model is a cross-sectional study of 373 hospitals. Regression analysis is used to estimate the relationship between Coronary Artery Bypass Graft (CABG) risk-adjusted mortality rates and hospital competition.</p> <p>Results</p> <p>Regression results show lower risk-adjusted mortality rates in the presence of a more competitive environment. This result holds for all alternative hospital market definitions. Non-profit hospitals do not have better patient outcomes than investor-owned hospitals. However, they tend to provide better quality in less competitive environments. CABG volume did not have a significant effect on patient outcomes.</p> <p>Conclusion</p> <p>Quality should be incorporated into the antitrust analysis. When mergers lead to higher prices and lower quality, thus lower social welfare, the antitrust challenge of hospital mergers is warranted. The impact of lower hospital competition on quality of care delivered by non-profit hospitals is ambiguous.</p
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