904 research outputs found
Predicting managers' mental health across countries: using country-level COVID-19 statistics
Background: There is limited research focusing on publicly available statistics on the Coronavirus disease 2019 (COVID-19) pandemic as predictors of mental health across countries. Managers are at risk of suffering from mental disorders during the pandemic because they face particular hardship.
Objective: We aim to predict mental disorder (anxiety and depression) symptoms of managers across countries using country-level COVID-19 statistics.
Methods: A two-wave online survey of 406 managers from 26 countries was performed in May and July 2020. We used logistic panel regression models for our main analyses and performed robustness checks using ordinary least squares regressions. In the sample, 26.5% of managers reached the cut-off levels for anxiety (General Anxiety Disorder-7; GAD-7) and 43.5% did so for depression (Patient Health Questionnaire-9; PHQ-9) symptoms.
Findings: We found that cumulative COVID-19 statistics (e.g., cumulative cases, cumulative cases per million, cumulative deaths, and cumulative deaths per million) predicted managers' anxiety and depression symptoms positively, whereas daily COVID-19 statistics (daily new cases, smoothed daily new cases, daily new deaths, smoothed daily new deaths, daily new cases per million, and smoothed daily new cases per million) predicted anxiety and depression symptoms negatively. In addition, the reproduction rate was a positive predictor, while stringency of governmental lockdown measures was a negative predictor. Individually, we found that the cumulative count of deaths is the most suitable single predictor of both anxiety and depression symptoms.
Conclusions: Cumulative COVID-19 statistics predicted managers' anxiety and depression symptoms positively, while non-cumulative daily COVID-19 statistics predicted anxiety and depression symptoms negatively. Cumulative count of deaths is the most suitable single predictor of both anxiety and depression symptoms. Reproduction rate was a positive predictor, while stringency of governmental lockdown measures was a negative predictor
Graphite Nanoeraser
We present here a method for cleaning intermediate-size (5~50nm)
contamination from highly oriented pyrolytic graphite. Electron beam deposition
causes a continuous increase of carbonaceous material on graphene and graphite
surfaces, which is difficult to remove by conventional techniques. Direct
mechanical wiping using a graphite nanoeraser is observed to drastically reduce
the amount of contamination. After the mechanical removal of contamination, the
graphite surfaces were able to self-retract after shearing, indicating that van
der Waals contact bonding is restored. Since contact bonding provides an
indication of a level of cleanliness normally only attainable in a high-quality
clean-room, we discuss potential applications in preparation of ultraclean
surfaces.Comment: 10 pages, two figure
Quantum Hall Ferromagnets
It is pointed out recently that the quantum Hall states in bilayer
systems behave like easy plane quantum ferromagnets. We study the
magnetotransport of these systems using their ``ferromagnetic" properties and a
novel spin-charge relation of their excitations. The general transport is a
combination of the ususal Hall transport and a time dependent transport with
time average. The latter is due to a phase slippage process in
and is characterized by two topological constants. (Figures will be
provided upon requests).Comment: 4 pages, Revtex, Ohio State Universit
Oscillatory Tunneling between Quantum Hall Systems
Electron tunneling between quantum Hall systems on the same two dimensional
plane separated by a narrow barrier is studied. We show that in the limit where
inelastic scattering time is much longer than the tunneling time, which can be
achieved in practice, electrons can tunnel back and forth through the barrier
continously, leading to an oscillating current in the absence of external
drives. The oscillatory behavior is dictated by a tunneling gap in the energy
spectrum. We shall discuss ways to generate oscillating currents and the
phenomenon of natural ``dephasing" between the tunneling currents of edge
states. The noise spectra of these junctions are also studied. They contain
singularites reflecting the existence of tunneling gaps as well as the inherent
oscillation in the system. (Figures will be given upon requests).Comment: 20 pages, OS
The effect of normal human serum on the mouse trypanosome Trypanosoma musculi in vitro and in vivo
Trypanosoma musculi, a common blood flagellate found in mice, is similar in morphology and life cycle to the rat trypanosome T. lewisi. Both species belong to the subgenus Herpetosoma, and as T. lewisi has recently been shown to be a zoonotic pathogen, there is concern that T. musculi could also be potentially infective to humans. To test this hypothesis, a well-established method, the normal human serum (NHS) incubation test, was carried out which distinguishes human and non-human infective trypanosomes. We found that T. musculi could grow in 0.31% NHS in vitro, and even kept their infectivity to mice after incubation with 10% NHS for 24âŻh. In in vivo experiments, T. musculi were only slightly affected by NHS injection, confirming that it was less sensitive to the NHS than T. b. brucei, but more sensitive than T. lewisi. This resistance probably does not rely on a restricted uptake of ApoL-1. Due to this partial resistance, we cannot definitively confirm that T. musculi has the potential for infection to humans. As resistance is less than that of T. lewisi, our data suggest that it is unlikely to be a zoonotic pathogen although we would advise caution in the case of immunocompromised people such as AIDS and cancer patients
Wigner Crystals Phases in Bilayer Quantum Hall Systems
(This is a substantially shortened version of the original abstract:)
The Wigner crystal phase diagram of the bilayer systems have been studied
using variational methods. Five crystal phases are obtained. As the layer
spacing increases, the system will undergo a sequence of phase transitions. A
common feature of most bilayer Wigner crystals is that they have mixed
(pseudo-spin) ferromagnetic and antiferromagnetic order.Comment: 19 figures. Figures will be provided upon request. Submitted in PRB
in Nov 94
Quantum Melting and Absence of Bose-Einstein Condensation in Two-Dimensional Vortex Matter
We demonstrate that quantum fluctuations suppress Bose-Einstein condensation
of quasi-two-dimensional bosons in a rapidly-rotating trap. Our conclusions
rest in part on an effective-Lagrangian description of the triangular vortex
lattice, and in part on microscopic Bogoliubov equations in the rapid-rotation
limit. We obtain analytic expressions for the collective-excitation dispersion,
which, in a rotating system, is quadratic rather than linear. Our estimates for
the boson filling factor at which the vortex lattice melts at zero temperature
due to quantum fluctuations are consistent with recent exact-diagonalization
calculations.Comment: 4 pages, 1 figures, version to appear in Phys. Rev. Let
Study on -wave Elastic Cross Section and Possible Bound States Within a Constituent Quark Model
In the framework of a chiral constituent quark model, considering the
contributions of annihilation and one-gluon annihilation, the
proton-antiproton -wave elastic scattering cross section experimental data
can be reproduced by adjusting properly one-gluon annihilation coupling
constant. Meanwhile, using the fixed model parameter, we do a dynamical
calculation for all possible -wave nucleon-antinucleon states, the results
show that, there is no -wave bound state as indicated by a strong
enhancement at threshold of in and decays.Comment: 15 pages, 8 figure
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