4,944 research outputs found
Vortical fluid and spin correlations in high-energy heavy-ion collisions
Fermions become polarized in a vortical fluid due to spin-vorticity coupling.
The spin polarization density is proportional to the local fluid vorticity at
the next-to-leading order of a gradient expansion in a quantum kinetic theory.
Spin correlations of two -hyperons can therefore reveal the vortical
structure of the dense matter in high-energy heavy-ion collisions. We employ a
(3+1)D viscous hydrodynamic model with event-by-event fluctuating initial
conditions from A MultiPhase Transport (AMPT) model to calculate the vorticity
distributions and spin correlations. The azimuthal correlation of the
transverse spin is shown to have a cosine form plus an offset due to a circular
structure of the transverse vorticity around the beam direction and global spin
polarization. The longitudinal spin correlation shows a structure of
vortex-pairing in the transverse plane due to the convective flow of hot spots
in the radial direction. The dependence on colliding energy, rapidity,
centrality and sensitivity to the shear viscosity are also investigated.Comment: 5 pages in Latex, 3 figure
Characteristics of The Cancer Genome Atlas cases relative to U.S. general population cancer cases
Dental safety net capacity: An innovative use of existing data to measure dentistsā clinical engagement in state Medicaid programs
Background
The demand for dentists available for state Medicaid populations has long outpaced the supply of such providers. To help understand the workforce dynamics, this study sought to develop a novel approach to measuring dentistsā relative contribution to the dental safety net and, using this new measurement, identify demographic and practice characteristics predictive of dentistsā willingness to participate in Indiana's Medicaid program.
Methods
We examined Medicaid claims data for 1,023 Indiana dentists. We fit generalized ordered logistic regression models to measure dentistsā level of clinical engagement with Medicaid. Using a partial proportional odds specification model, we estimated proportional adjusted odds ratios for covariates and separate estimates for each contrast of nonproportional covariates.
Results
Though 75% of Medicaidāenrolled dentists were active providers, only 27% of them had 800 or more claims during fiscal year 2015. As has been shown in previous studies, our findings from the proportional odds model reinforced certain demographic and practice characteristics to be predictive of dentistsā participation in state Medicaid programs.
Conclusions
In addition to confirming predictive factors for Medicaid enrollment, this study validated the clinical engagement measure as a reliable method to assess the level of Medicaid participation. Prior studies have been limited by selfāreported data and variations in Medicaid claims reporting
Protein kinase C-dependent signaling controls the midgut epithelial barrier to malaria parasite infection in anopheline mosquitoes.
Anopheline mosquitoes are the primary vectors of parasites in the genus Plasmodium, the causative agents of malaria. Malaria parasites undergo a series of complex transformations upon ingestion by the mosquito host. During this process, the physical barrier of the midgut epithelium, along with innate immune defenses, functionally restrict parasite development. Although these defenses have been studied for some time, the regulatory factors that control them are poorly understood. The protein kinase C (PKC) gene family consists of serine/threonine kinases that serve as central signaling molecules and regulators of a broad spectrum of cellular processes including epithelial barrier function and immunity. Indeed, PKCs are highly conserved, ranging from 7 isoforms in Drosophila to 16 isoforms in mammals, yet none have been identified in mosquitoes. Despite conservation of the PKC gene family and their potential as targets for transmission-blocking strategies for malaria, no direct connections between PKCs, the mosquito immune response or epithelial barrier integrity are known. Here, we identify and characterize six PKC gene family members--PKCĪ“, PKCĪµ, PKCĪ¶, PKD, PKN, and an indeterminate conventional PKC--in Anopheles gambiae and Anopheles stephensi. Sequence and phylogenetic analyses of the anopheline PKCs support most subfamily assignments. All six PKCs are expressed in the midgut epithelia of A. gambiae and A. stephensi post-blood feeding, indicating availability for signaling in a tissue that is critical for malaria parasite development. Although inhibition of PKC enzymatic activity decreased NF-ĪŗB-regulated anti-microbial peptide expression in mosquito cells in vitro, PKC inhibition had no effect on expression of a panel of immune genes in the midgut epithelium in vivo. PKC inhibition did, however, significantly increase midgut barrier integrity and decrease development of P. falciparum oocysts in A. stephensi, suggesting that PKC-dependent signaling is a negative regulator of epithelial barrier function and a potential new target for transmission-blocking strategies
Simulation of quiet-sun hard x-rays related to solar wind superhalo electrons
In this paper, we propose that the accelerated electrons in the quiet Sun could collide with the solar atmosphere to emit Hard X-rays (HXRs) via non-thermal bremsstrahlung, while some of these electrons would move upwards and escape into the interplanetary medium, to form a superhalo electron population measured in the solar wind. After considering the electron energy loss due to Coulomb collisions and the ambipolar electrostatic potential, we find that the sources of the superhalo could only occur high in the corona (at a heliocentric altitude ā³1.9 Rā (the mean radius of the Sun)), to remain a power-law shape of electron spectrum as observed by STEREO at 1AU near solar minimum (Wang et al., 2012). The modeled quiet-Sun HXRs related to the superhalo electrons fit well to a power-law spectrum, fā¼ĪµāĪ³, with an index Ī³ ā 2.0 - 2.3 (3.3 - 3.7) at 10 - 100 keV, for the warm/cold thick-target (thin-target) emissions produced by the downward-traveling (upward-traveling) accelerated electrons. These simulated quiet-Sun spectra are significantly harder than the observed spectra of most solar HXR flares. Assuming that the quiet-Sun sources cover 5% of the solar surface, the modeled thin-target HXRs are more than six orders of magnitude weaker than the RHESSI upper limit for quiet-Sun HXRs (Hannah et al., 2010). Using the thick-target model for the downward-traveling electrons, the RHESSI upper limit restricts the number of downward-traveling electrons to at most ā3 times the number of escaping electrons. This ratio is fundamentally different from what is observed during solar flares associated with escaping electrons where the fraction of downward-traveling electrons dominates by a factor of 100 to 1000 over the escaping population
Observations of Reconnection Flows in a Flare on the Solar Disk
Magnetic reconnection is a well-accepted part of the theory of solar eruptive
events, though the evidence is still circumstantial. Intrinsic to the
reconnection picture of a solar eruptive event, particularly in the standard
model for two-ribbon flares ("CSHKP" model), are an advective flow of
magnetized plasma into the reconnection region, expansion of field above the
reconnection region as a flux rope erupts, retraction of heated
post-reconnection loops, and downflows of cooling plasma along those loops. We
report on a unique set of SDO/AIA imaging and Hinode/EIS spectroscopic
observations of the disk flare SOL2016-03-23T03:54 in which all four flows are
present simultaneously. This includes spectroscopic evidence for a plasma
upflow in association with large-scale expanding closed inflow field. The
reconnection inflows are symmetric, and consistent with fast reconnection, and
the post-reconnection loops show a clear cooling and deceleration as they
retract. Observations of coronal reconnection flows are still rare, and most
events are observed at the solar limb, obscured by complex foregrounds, making
their relationship to the flare ribbons, cusp field and arcades formed in the
lower atmosphere difficult to interpret. The disk location and favorable
perspective of this event have removed these ambiguities giving a clear picture
of the reconnection dynamics.Comment: 9 pages, 5 figures, and 1 table. Accepted for publication in ApJ
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