The general reduction in the thicknesses of critical dielectric layers driven by Moore's law scaling has led to increasingly more manageable total-ionizing-dose (TID) response over the last ~50 ...years. Effects of oxide, interface, and border traps in MOS gate oxides on TID response are now mostly well known for SiO 2 gate dielectrics, and the leakage currents due to isolation oxides can be conservatively bounded with existing test methods. Radiation hardened and/or radiation-tolerant technologies have been developed that can survive doses that exceed 1 Mrad(SiO 2 ). Advances in computing technology enabled by Moore's law scaling and concomitant enhancements in computational techniques have greatly facilitated the modeling and simulation of TID effects in microelectronic devices and ICs. However, the TID response of nanoscale MOS devices with advanced gate stacks and high-<inline-formula> <tex-math notation="LaTeX">{K} </tex-math></inline-formula> gate dielectrics, and/or alternative materials to Si, is often more complex than for MOS devices with SiO 2 gate oxides. TID challenges remain for linear bipolar technologies that exhibit enhanced low-dose-rate sensitivity and for microelectronic devices that must function at doses above ~100 Mrad(SiO 2 ), e.g., in high luminosity accelerator environments. TID effects have also recently been observed in wide bandgap semiconductor devices (e.g., GaN/AlGaN HEMTs) with no gate oxide.
Ordinary least squares and stepwise selection are widespread in behavioral science research; however, these methods are well known to encounter overfitting problems such that R
2
and regression ...coefficients may be inflated while standard errors and p values may be deflated, ultimately reducing both the parsimony of the model and the generalizability of conclusions. More optimal methods for selecting predictors and estimating regression coefficients such as regularization methods (e.g., Lasso) have existed for decades, are widely implemented in other disciplines, and are available in mainstream software, yet, these methods are essentially invisible in the behavioral science literature while the use of sub optimal methods continues to proliferate. This paper discusses potential issues with standard statistical models, provides an introduction to regularization with specific details on both Lasso and its related predecessor ridge regression, provides an example analysis and code for running a Lasso analysis in R and SAS, and discusses limitations and related methods.
Although implicit bias in medical training has long been suspected, it has been difficult to study using objective measures, and the influence of sex and gender in the evaluation of medical trainees ...is unknown. The emergency medicine (EM) milestones provide a standardized framework for longitudinal resident assessment, allowing for analysis of resident performance across all years and programs at a scope and level of detail never previously possible.
To compare faculty-observed training milestone attainment of male vs female residency training.
This multicenter, longitudinal, retrospective cohort study took place at 8 community and academic EM training programs across the United States from July 1, 2013, to July 1, 2015, using a real-time, mobile-based, direct-observation evaluation tool. The study examined 33 456 direct-observation subcompetency evaluations of 359 EM residents by 285 faculty members.
Milestone attainment for male and female EM residents as observed by male and female faculty throughout residency and analyzed using multilevel mixed-effects linear regression modeling.
A total of 33 456 direct-observation evaluations were collected from 359 EM residents (237 men 66.0% and 122 women 34.0%) by 285 faculty members (194 men 68.1% and 91 women 31.9%) during the study period. Female and male residents achieved similar milestone levels during the first year of residency. However, the rate of milestone attainment was 12.7% (0.07 levels per year) higher for male residents through all of residency (95% CI, 0.04-0.09). By graduation, men scored approximately 0.15 milestone levels higher than women, which is equivalent to 3 to 4 months of additional training, given that the average resident gains approximately 0.52 levels per year using our model (95% CI, 0.49-0.54). No statistically significant differences in scores were found based on faculty evaluator gender (effect size difference, 0.02 milestone levels; 95% CI for males, -0.09 to 0.11) or evaluator-evaluatee gender pairing (effect size difference, -0.02 milestone levels; 95% CI for interaction, -0.05 to 0.01).
Although male and female residents receive similar evaluations at the beginning of residency, the rate of milestone attainment throughout training was higher for male than female residents across all EM subcompetencies, leading to a gender gap in evaluations that continues until graduation. Faculty should be cognizant of possible gender bias when evaluating medical trainees.
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The first neutron star (NS) merger observed by advanced LIGO and Virgo, GW170817, and its fireworks of electromagnetic counterparts across the entire electromagnetic spectrum marked the beginning ...of multi-messenger astronomy and astrophysics with gravitational waves. The ultraviolet, optical, and near-infrared emission was consistent with being powered by the radioactive decay of nuclei synthesized in the merger ejecta by the rapid neutron capture process (r-process). Starting from an outline of the inferred properties of this “kilonova” emission, I discuss possible astrophysical sites for r-process nucleosynthesis in NS mergers, arguing that the heaviest r-process elements synthesized in this event most likely originated in outflows from a post-merger accretion disk. I compare the inferred properties of r-process element production in GW170817 to current observational constraints on galactic heavy r-process nucleosynthesis and discuss challenges merger-only models face in explaining the r-process content of our galaxy. Based on the observational properties of GW170817 and recent theoretical progress on r-process nucleosynthesis in collapsars, I then show how GW170817 points to collapsars as the dominant source of r-process enrichment in the Milky Way. These rare core-collapse events arguably better satisfy existing constraints and overcome problems related to r-process enrichment in various environments that NS mergers face. Finally, I comment on the universality of the r-process and on how variations in light r-process elements can be obtained both in NS mergers and collapsars.
In order to generate skilled and efficient actions, the motor system must find solutions to several problems inherent in sensorimotor control, including nonlinearity, nonstationarity, delays, ...redundancy, uncertainty, and noise. We review these problems and five computational mechanisms that the brain may use to limit their deleterious effects: optimal feedback control, impedance control, predictive control, Bayesian decision theory, and sensorimotor learning. Together, these computational mechanisms allow skilled and fluent sensorimotor behavior.
Merging binaries consisting of two neutron stars (NSs) or an NS and a stellar-mass black hole typically form a massive accretion torus around the remnant black hole or long-lived NS. Outflows from ...these neutrino-cooled accretion disks represent an important site for r-process nucleosynthesis and the generation of kilonovae. We present the first three-dimensional, general-relativistic magnetohydrodynamic (GRMHD) simulations including weak interactions and a realistic equation of state of such accretion disks over viscous timescales (380 ms). We witness the emergence of steady-state MHD turbulence, a magnetic dynamo with an ∼20 ms cycle, and the generation of a "hot" disk corona that launches powerful thermal outflows aided by the energy released as free nucleons recombine into -particles. We identify a self-regulation mechanism that keeps the midplane electron fraction low (Ye ∼ 0.1) over viscous timescales. This neutron-rich reservoir, in turn, feeds outflows that retain a sufficiently low value of Ye 0.2 to robustly synthesize third-peak r-process elements. The quasi-spherical outflows are projected to unbind 40% of the initial disk mass with typical asymptotic escape velocities of 0.1c and may thus represent the dominant mass ejection mechanism in NS-NS mergers. Including neutrino absorption, our findings agree with previous hydrodynamical -disk simulations that the entire range of r-process nuclei from the first to the third r-process peak can be synthesized in the outflows, in good agreement with observed solar system abundances. The asymptotic escape velocities and quantity of ejecta, when extrapolated to moderately higher disk masses, are consistent with those needed to explain the red kilonova emission following the NS merger GW170817.
COVID-19 vaccination: The road ahead Altmann, Daniel M; Boyton, Rosemary J
Science (American Association for the Advancement of Science),
03/2022, Volume:
375, Issue:
6585
Journal Article
Peer reviewed
A diverse array of successful, first-generation SARS-CoV-2 vaccines have played a huge role in efforts to bring the COVID-19 pandemic under control, even though inequitable distribution still leaves ...many vulnerable. Additional challenges loom for the next phase. These include optimizing the immunological rationale for boosting-how often and with what-and the best approaches for building a future-proofed, durable immune repertoire to protect against oncoming viral variants, including in children. The landscape of vaccine producers and technologies is likely to become even more heterogeneous. There is a need now for appraisal of future approaches: While some favor frequent boosting with the first-generation, ancestral spike vaccines, others propose frequent readjustment using current variant sequences, polyvalent vaccines, or pan-coronavirus strategies.
Multilevel models are an increasingly popular method to analyze data that originate from a clustered or hierarchical structure. To effectively utilize multilevel models, one must have an adequately ...large number of clusters; otherwise, some model parameters will be estimated with bias. The goals for this paper are to (1) raise awareness of the problems associated with a small number of clusters, (2) review previous studies on multilevel models with a small number of clusters, (3) to provide an illustrative simulation to demonstrate how a simple model becomes adversely affected by small numbers of clusters, (4) to provide researchers with remedies if they encounter clustered data with a small number of clusters, and (5) to outline methodological topics that have yet to be addressed in the literature.
Abstract Background Treatment-related cardiac death is the primary, noncancer cause of mortality in adult survivors of childhood malignancies. Early detection of cardiac dysfunction may identify a ...high-risk subset of survivors for early intervention. Objectives This study sought to determine the prevalence of cardiac dysfunction in adult survivors of childhood malignancies. Methods Echocardiographic assessment included 3-dimensional (3D) left ventricular ejection fraction (LVEF), global longitudinal and circumferential myocardial strain, and diastolic function, graded per American Society of Echocardiography guidelines in 1,820 adult (median age 31 years; range: 18 to 65 years) survivors of childhood cancer (median time from diagnosis 23 years; range: 10 to 48 years) exposed to anthracycline chemotherapy (n = 1,050), chest-directed radiotherapy (n = 306), or both (n = 464). Results Only 5.8% of survivors had abnormal 3D LVEFs (<50%). However, 32.1% of survivors with normal 3D LVEFs had evidence of cardiac dysfunction by global longitudinal strain (28%), American Society of Echocardiography–graded diastolic assessment (8.7%), or both. Abnormal global longitudinal strain was associated with chest-directed radiotherapy at 1 to 19.9 Gy (rate ratio RR: 1.38; 95% confidence interval CI: 1.14 to 1.66), 20 to 29.9 Gy (RR: 1.65; 95% CI: 1.31 to 2.08), and >30 Gy (RR: 2.39; 95% CI: 1.79 to 3.18) and anthracycline dose > 300 mg/m2 (RR: 1.72; 95% CI: 1.31 to 2.26). Survivors with metabolic syndrome were twice as likely to have abnormal global longitudinal strain (RR: 1.94; 95% CI: 1.66 to 2.28) and abnormal diastolic function (RR: 1.68; 95% CI: 1.39 to 2.03) but not abnormal 3D LVEFs (RR: 1.07; 95% CI: 0.74 to 1.53). Conclusions Abnormal global longitudinal strain and diastolic function are more prevalent than reduced 3D LVEF and are associated with treatment exposure. They may identify a subset of survivors at higher risk for poor clinical cardiac outcomes who may benefit from early medical intervention.
Taking notes on laptops rather than in longhand is increasingly common. Many researchers have suggested that laptop note taking is less effective than longhand note taking for learning. Prior studies ...have primarily focused on students' capacity for multitasking and distraction when using laptops. The present research suggests that even when laptops are used solely to take notes, they may still be impairing learning because their use results in shallower processing. In three studies, we found that students who took notes on laptops performed worse on conceptual questions than students who took notes longhand. We show that whereas taking more notes can be beneficial, laptop note takers' tendency to transcribe lectures verbatim rather than processing information and reframing it in their own words is detrimental to learning.
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