Low off-state Leakage Currents in AlGaN/GaN High Electron Mobility Transistors By Employing A Highly Stressed SiNx Surface Passivation Layer

In this study, the impact of the stress in SiNx surface passivation layers on off-state drain and gate leakage currents and off-state breakdown voltage in AlGaN/GaN High Electron Mobility Transistors (HEMTs) is assessed. The SiNx films were deposited at room temperature by inductively coupled plasma chemical vapour deposition (ICP-CVD). Compared to unpassivated devices, the off-state drain and gate leakage currents of AlGaN/GaN HEMTs is increased by up to 2 orders of magnitude for a 200 nm thick SiNx passivation layer with 309 MPa compressive stress. The use of a bilayer SiNx passivation scheme comprising 70 nm SiNx with 309 MPa compressive stress followed by 130 nm SiNx with 880 MPa compressive stress resulted in off-state drain and gate leakage currents reduced by up to 1 order of magnitude when compared to unpassivated devices

The photon production and collective flows from magnetic induced fusion and splitting in early stage of high energy nuclear collision

We present an event-by-event study of photon production in the early stage of high energy nuclear collisions, where the system is dominant by highly occupied of gluons. The photons are produced through the gluon fusion and splitting processes when strong magnetic field is included. We study the spectra and collective flows of the photons and show their dependence on transverse momentum $q_{T}$. It is found that the photons from the boost invariant evolving glasma provide visible enhancement on spectrum and obvious contribution on $v_{2}$ of total the direct photons in large $q_{T}$ region. The results, by weighting on top of parton-hadron-string dynamics (PHSD) model, agree even better with experiment measurements in Au-Au 20\%-40\% centrality collisions at $\sqrt{s_{NN}}=200$GeV.Comment: 8 pages, 6 figure

180nm metal gate, high-k dielectric, implant-free III--V MOSFETs with transconductance of over 425 μS/μm

Abstract: Data is reported from 180 nm gate length GaAs n-MOSFETs with drive current (Ids,sat) of 386 μA/μm (Vg=Vd =1.5 V), extrinsic transconductance (gm) of 426 μS/μm, gate leakage ( jg,limit) of 44 nA/cm2, and on resistance (Ron) of 1640 Ω μm. The gm and Ron metrics are the best values reported to date for III-V MOSFETs, and indicate their potential for scaling to deca-nanometre dimensions

Chameleon f(R) gravity on the Virgo cluster scale

Models of modified gravity offer promising alternatives to the concordance Λ cold dark matter (ΛCDM) cosmology to explain the late-time acceleration of the universe. A popular such model is f(R) gravity, in which the Ricci scalar in the Einstein-Hilbert action is replaced by a general function of it. We study the f(R) model of Hu & Sawicki, which recovers standard general relativity in high-density regimes, while reproducing the desired late time acceleration at cosmological scales. We run a suite of high-resolution zoom simulations using the ecosmog code to examine the effect of f(R) gravity on the properties of a halo that is analogous to the Virgo cluster. We show that the velocity dispersion profiles can potentially discriminate between f(R) models and ΛCDM, and provide complementary analysis of lensing signal profiles to explore the possibility to further distinguish the different f(R) models. Our results confirm the techniques explored by Cabré etal. to quantify the effect of environment in the behaviour of f(R) gravity, and we extend them to study halo satellites at various redshifts. We find that the modified gravity effects in our models are most observable at low redshifts, and that effects are generally stronger for satellites far from the centre of the main halo. We show that the screening properties of halo satellites trace very well that of dark matter particles, which means that low-resolution simulations in which subhaloes are not very well resolved can in principle be used to study satellite properties. We discuss observables, particularly for halo satellites, that can potentially be used to constrain the observational viability of f(R) gravit

Demographics, Activities, and Environmental Factors Impact Burnout in a National Survey of Emergency Medicine Residents

Introduction: Burnout in emergency medicine and in residency training has been well-described. The impact of demographic, individual, and programmatic factors on burnout have not previously been determined in a national survey of emergency medicine residents. This study aimed to identify personal and environmental factors impacting resident burnout in a national sample of emergency medicine residents. Methods: A prospective Emergency Medicine Resident Wellness Survey was administered in 2017. We surveyed respondents on demographic, personal, and environmental factors; each respondent also completed the Maslach Burnout Inventory - Human Services Survey. Linear regressions were used to identify variables associated with the Maslach Burnout Inventory’s subscales of burnout (depersonalization, emotional exhaustion, and personal achievement). Results: The survey was completed by 1,522 of 7,186 (21.2%) eligible EM residents. Respondents represented 193 of 247 (78.1%) Emergency Medicine residency programs. Increased levels of depersonalization were associated with graduation from a US medical school, female gender, and increase in respondent age. Trainees who were parents and who graduated from an osteopathic (vs. allopathic) medical school were found to have decreased levels of depersonalization. Emotional exhaustion was decreased in respondents who took breaks while on shift and who engaged in regular studying. Conclusion: While some individual characteristics impact burnout, environmental factors also play a significant role, and should be a target of system-level interventions to improve trainee well-being

Factor Structure and Measurement Invariance of the Maslach Burnout Inventory in Emergency Medicine Residents

Introduction: Emergency medicine residents suffer from high rates of occupational burnout. Recent research has focused on identifying risk and protective factors for burnout as well as targets for intervention. This research has primarily employed the Maslach Burnout Inventory to evaluate burnout in this population. Factor analytic work has identified three underlying factors measured by the Maslach Burnout Inventory: Emotional Exhaustion, Depersonalization, and Personal Accomplishment. However, this three-factor structure has not been evaluated in emergency medicine residents. Furthermore, its structural equivalence has not been demonstrated across commonly-studied risk factors, such as gender and year of post-graduate training. In the present study, we evaluated the structure of the Maslach Burnout Inventory in emergency medicine residents as well as its measurement invariance across gender and post-graduate year. Methods: 1522 emergency medicine residents (21.1% of all US residents from 78.1% of US residency programs) were recruited as part of the 2017 National EM Resident Wellness Survey and completed the Maslach Burnout Inventory – Human Services Survey. The factor structure and measurement invariance across both respondent gender and post-graduate year were evaluated using a series of confirmatory factor analyses. Exploratory analyses evaluated whether burnout scores differed across men/women and post-graduate years 1, 2, and 3+ using a structural equation model. Results: The three-factor structure was observed after minor modifications which replicated in cross-validation. This structure was invariant across both gender and post-graduate year at the configural, metric, and scalar levels. Emotional exhaustion scores were higher for female residents and scores on all of the MBI scales indicated greater burnout for more advanced residents. Conclusions: These results indicate the Maslach Burnout Inventory is fully structurally equivalent across gender and post-graduate year and further validates its use in this population. Secondary evaluations of the latent means revealed that female residents tend to have higher scores on Emotional Exhaustion and that scores on all factors tend to worsen as trainees progress through their residency

COLD GASS, an IRAM Legacy Survey of Molecular Gas in Massive Galaxies: III. Comparison with semi-analytic models of galaxy formation

We compare the semi-analytic models of galaxy formation of Fu et al. (2010), which track the evolution of the radial profiles of atomic and molecular gas in galaxies, with gas fraction scaling relations derived from the COLD GASS survey (Saintonge et al 2011). The models provide a good description of how condensed baryons in galaxies with gas are partitioned into stars, atomic and molecular gas as a function of galaxy stellar mass and surface density. The models do not reproduce the tight observed relation between stellar surface density and bulge-to-disk ratio for this population. We then turn to an analysis of the"quenched" population of galaxies without detectable cold gas. The current implementation of radio-mode feedback in the models disagrees strongly with the data. In the models, gas cooling shuts down in nearly all galaxies in dark matter halos above a mass of 10**12 M_sun. As a result, stellar mass is the observable that best predicts whether a galaxy has little or no neutral gas. In contrast, our data show that quenching is largely independent of stellar mass. Instead, there are clear thresholds in bulge-to-disk ratio and in stellar surface density that demarcate the location of quenched galaxies. We propose that processes associated with bulge formation play a key role in depleting the neutral gas in galaxies and that further gas accretion is suppressed following the formation of the bulge, even in dark matter halos of low mass.Comment: 12 figures, accepted for publication in MNRAS, the COLD GASS data is available at http://www.mpa-garching.mpg.de/COLD_GASS/data.shtm