3,056 research outputs found
Sporadic Aurora near Geomagnetic Equator: In the Philippines, on 27 October 1856
While low latitude auroral displays are normally considered to be a
manifestation of magnetic storms of considerable size, Silverman (2003, JGR,
108, A4) reported numerous "sporadic auroras" which appear locally at
relatively low magnetic latitudes during times of just moderate magnetic
activity. Here, a case study is presented of an aurora near the geomagnetic
equator based on a report from the Philippine Islands on 27 October 1856. An
analysis of this report shows it to be consistent with the known cases of
sporadic aurorae except for its considerably low magnetic latitude. The record
also suggests that extremely low-latitude aurora is not always accompanied with
large magnetic storms. The description of its brief appearance leads to a
possible physical explanation based on an ephemeral magnetospheric disturbance
provoking this sporadic aurora.Comment: 15 pages, 3 figures, accepted for publication in Annales Geophysicae
on 18 August 201
BCS-BEC crossover in a relativistic superfluid and its significance to quark matter
The character change of a superfluid state due to the variation of the
attractive force is investigated in the relativistic framework with a massive
fermion. Two crossovers are found. One is a crossover from the usual BCS state
to the Bose-Einstein condensation (BEC) of bound fermion pairs. The other is
from the BEC to the relativistic Bose-Einstein condensation (RBEC) of nearly
massless bound pairs where antiparticles as well as particles dominate the
thermodynamics. Possible realization of the BEC and RBEC states in the quark
matter is also pointed out.Comment: 5 pages, 1 figure, revtex4; (v2) text has been clarified, references
updated; (v3) final version to appear in Phys. Rev.
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Association between physician characteristics and payments from industry in 2015-2017: observational study.
OBJECTIVE:To investigate the association between physician characteristics and the value of industry payments. DESIGN:Observational study. SETTING AND PARTICIPANTS:Using the 2015-2017 Open Payments reports of industry payments linked to the Physician Compare database, we examined the association between physician characteristics (physician sex, years in practice, medical school attended and specialty) and the industry payment value, adjusting for other physician characteristic and institution fixed effects (effectively comparing physicians practicing at the same institution). MAIN OUTCOME MEASURES:Our primary outcome was the value of total industry payments to physicians including (1) general payments (all forms of payments other than those classified for research purpose, eg, consulting fees, food, beverage), (2) research payments (payments for research endeavours under a written contract or protocol) and (3) ownership interests (eg, stock or stock options, bonds). We also investigated each category of payment separately. RESULTS:Of 544 264 physicians treating Medicare beneficiaries, a total of $5.8 billion in industry payments were made to 365 801 physicians during 2015-2017. The top 5% of physicians, by cumulative payments, accounted for 91% of industry payments. Within the same institution, male physicians, physicians with 21-30 years in practice and physicians who attended top 50 US medical schools (based on the research ranking) received higher industry payments. Across specialties, orthopaedic surgeons, neurosurgeons and endocrinologists received the highest payments. When we investigated individual types of payment, we found that orthopaedic surgeons received the highest general payments; haematologists/oncologists were the most likely to receive research payments and surgeons were the most likely to receive ownership interests compared with other types of physicians. CONCLUSIONS:Industry payments to physicians were highly concentrated among a small number of physicians. Male sex, longer length of time in clinical practice, graduated from a top-ranked US medical school and practicing certain specialties, were independently associated with higher industry payments
Schroedinger functional formalism with domain-wall fermion
Finite volume renormalization scheme is one of the most fascinating scheme
for non-perturbative renormalization on lattice.
By using the step scaling function one can follow running of renormalized
quantities with reasonable cost.
It has been established the Schroedinger functional is very convenient to
define a field theory in a finite volume for the renormalization scheme.
The Schroedinger functional, which is characterized by a
Dirichlet boundary condition in temporal direction, is well defined and works
well for the Yang-Mills theory and QCD with the Wilson fermion.
However one easily runs into difficulties if one sets the same sort of the
Dirichlet boundary condition for the overlap Dirac operator or the domain-wall
fermion.
In this paper we propose an orbifolding projection procedure to impose the
Schroedinger functional Dirichlet boundary condition on the domain-wall
fermion.Comment: 32 page
A fundamental test for stellar feedback recipes in galaxy simulations
Direct comparisons between galaxy simulations and observations that both
reach scales < 100 pc are strong tools to investigate the cloud-scale physics
of star formation and feedback in nearby galaxies. Here we carry out such a
comparison for hydrodynamical simulations of a Milky Way-like galaxy, including
stochastic star formation, HII region and supernova feedback, and chemical
post-processing at 8 pc resolution. Our simulation shows excellent agreement
with almost all kpc-scale and larger observables, including total star
formation rates, radial profiles of CO, HI, and star formation through the
galactic disc, mass ratios of the ISM components, both whole-galaxy and
resolved Kennicutt-Schmidt relations, and giant molecular cloud properties.
However, we find that our simulation does not reproduce the observed
de-correlation between tracers of gas and star formation on < 100 pc scales,
known as the star formation 'uncertainty principle', which indicates that
observed clouds undergo rapid evolutionary lifecycles. We conclude that the
discrepancy is driven by insufficiently-strong pre-supernova feedback in our
simulation, which does not disperse the surrounding gas completely, leaving
star formation tracer emission too strongly associated with molecular gas
tracer emission, inconsistent with observations. This result implies that the
cloud-scale de-correlation of gas and star formation is a fundamental test for
feedback prescriptions in galaxy simulations, one that can fail even in
simulations that reproduce all other macroscopic properties of star-forming
galaxies.Comment: 13 pages, 10 figures, accepted for publication in MNRA
Comparing simulated Al maps to gamma-ray measurements
© ESO 2019.Context. The diffuse gamma-ray emission of at 1.8 MeV reflects ongoing nucleosynthesis in the Milky Way, and traces massive-star feedback in the interstellar medium due to its 1 Myr radioactive lifetime. Interstellar-medium morphology and dynamics are investigated in astrophysics through 3D hydrodynamic simulations in fine detail, as only few suitable astronomical probes are available. Aims. We compare a galactic-scale hydrodynamic simulation of the Galaxy's interstellar medium, including feedback and nucleosynthesis, with gamma-ray data on emission in the Milky Way extracting constraints that are only weakly dependent on the particular realisation of the simulation or Galaxy structure. Methods. Due to constraints and biases in both the simulations and the gamma-ray observations, such comparisons are not straightforward. For a direct comparison, we perform maximum likelihood fits of simulated sky maps as well as observation-based maximum entropy maps to measurements with INTEGRAL/SPI. To study general morphological properties, we compare the scale heights of emission produced by the simulation to INTEGRAL/SPI measurements.} Results. The direct comparison shows that the simulation describes the observed inner Galaxy well, but differs significantly from the observed full-sky emission morphology. Comparing the scale height distribution, we see similarities for small scale height features and a mismatch at larger scale heights. We attribute this to the prominent foreground emission sites that are not captured by the simulation.Peer reviewedFinal Accepted Versio
Critical property of spin-glass transition in a bond-disordered classical antiferromagnetic Heisenberg model with a biquadratic interaction
Motivated by puzzling spin-glass behaviors observed in many pyrochlore-based
magnets, effects of magnetoelastic coupling to local lattice distortions were
recently studied by the authors for a bond-disordered antiferromagnet on a
pyrochlore lattice [Phys. Rev. Lett. 107, 047204 (2011)]. Here, we extend the
analyses with focusing on the critical property of the spin-glass transition
which occurs concomitantly with a nematic transition. Finite-size scaling
analyses are performed up to a larger system size with 8192 spins to estimate
the transition temperature and critical exponents. The exponents are compared
with those in the absence of the magnetoelastic coupling and with those for the
canonical spin-glass systems. We also discuss the temperature dependence of the
specific heat in comparison with that in canonical spin-glass systems as well
as an experimental result.Comment: 4 pages, 2 figures, proceedings for LT2
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