It is an experimental fact that multi-particle correlations in the final states of high-energy nucleus-nucleus collisions are sensitive to collective correlations of nucleons in the wave functions of ...the colliding nuclei. Here, I show that this connection is more direct than it intuitively seems. With an energy deposition scheme inspired by high-energy quantum chromodynamics, and within a linearized description of initial-state fluctuations in the quark-gluon plasma, I exhibit relations between
N
-particle correlations in the final states of nuclear collisions and
N
-nucleon density distributions in the colliding nuclei. This result formally justifies the sensitivity of the outcome of high-energy collisions to features such as nuclear deformations. It paves the way, thus, to systematic studies of the impact of state-of-the-art nuclear interactions in such processes.
I show that the average transverse momentum, 〈pt〉, of the hadrons emitted in relativistic nuclear collisions can be used as a “knob” to control the strength of the magnetic field induced by the ...spectator and the participant protons over the overlap region. I thus argue that any observable sensitive to this magnetic field is nontrivially correlated with 〈pt〉 at a given collision centrality.
We analyze observations of energetic charged particles associated with many strong interplanetary shocks seen by Advanced Composition Explorer. We focus primarily on 47-187 keV suprathermal protons ...and restrict our analysis to strong interplanetary shocks (Alfven Mach number >3 and the shock density compression >2.5). Eighteen shocks meeting this criterion from 1998 to 2003 were analyzed. All 18 had enhancements of the 47-65 keV proton intensity above the intensity seen one day before the shock. In 17 events, the particle intensity either rose to a quasi-plateau or peaked within 10 minutes of the shock. Most had intensities at the shock exceeding 100 times more than that seen the day before the shock arrived. The time-intensity profiles of the energetic proton events in many cases reveal a rise before the shock passage reaching a quasi-plateau or local peak at the shock, followed by a gradual decline. This suggests that the shock itself is the source of energetic particles. Energy spectra behind the shock were fit to an assumed power law over the interval from 46 to 187 keV, and the resulting spectral index was compared to the plasma density jump across each shock. Most events agree with the prediction of diffusive shock acceleration theory to within the observational uncertainties. We also analyzed a few selected events to determine the particle spatial diffusion coefficients and acceleration timescales. We find that the time to accelerate protons to ~50 keV is of the order of an hour.
Abstract
The random advection of passive additives in a turbulent fluid plays an important role in solar physics, astrophysics, and atmospheric sciences. We concern ourselves here with the case where ...the fluctuations are not statistically homogeneous in space, and, hence, where the transport coefficients vary with position. Using a numerical model in which the fluid turbulence is defined kinematically, we show that the evolution of the distribution of passive tracers in the fluid is not always governed by the ordinary diffusion equation. We find it is governed by a more general transport equation whose form depends on the nature of the turbulence, particularly on its compressibility, or divergence. The more general transport equation resembles the ordinary diffusion equation, but the transport coefficient appears in two places and is raised to a power that depends on the divergence of the fluid velocity. If the flow has zero divergence, the case for incompressible turbulence, the resulting transport equation is found to be the regular diffusion equation.
In this review, the most recent advances in the synthesis and catalytic applications of covalently supported ionic liquid (IL) phases will be discussed. This class of recyclable catalytic materials ...is based on the covalent attachment of several types of ammonium salts, usually imidazolium, but also thiazolium, triazolium, and pyrrolidinium salts, on the surface of different supports, for example, silica, periodic mesoporous organosilica, polystyrene, magnetic‐based materials, carbon nanotubes (NTs), halloysite NTs, polyhedral oligomeric silsesquioxane (POSS), and fullerenes. Moreover, poly(ionic liquid) materials, in which the IL‐based structure also acts as a support, will be considered. The synthetic applications of these materials will be presented, with special emphasis on their roles as catalysts, without added organocatalysts or metal‐based catalysts, as supports for organocatalysts, and as supports for metal‐based catalysts.
Multitasking catalytic materials: Covalently supported ionic liquid phases (cSILP) are useful catalytic materials for many organic transformations. This Review takes a look at the most recent advances in the synthesis and catalytic applications of cSILP.
The human retinal pigment epithelium (RPE) and choroid are complex tissues that provide crucial support to the retina. Disease affecting either of these supportive tissues can lead to irreversible ...blindness in the setting of age-related macular degeneration. In this study, single-cell RNA sequencing was performed on macular and peripheral regions of RPE-choroid from 7 human donor eyes in 2 independent experiments. In the first experiment, total RPE/choroid preparations were evaluated and expression profiles specific to RPE and major choroidal cell populations were identified. As choroidal endothelial cells represent a minority of the total RPE/choroidal cell population but are strongly implicated in age-related macular degeneration (AMD) pathogenesis, a second single-cell RNA-sequencing experiment was performed using endothelial cells enriched by magnetic separation. In this second study, we identified gene expression signatures along the choroidal vascular tree, classifying the transcriptome of human choriocapillaris, arterial, and venous endothelial cells. We found that the choriocapillaris highly and specifically expresses the regulator of cell cycle gene (RGCC), a gene that responds to complement activation and induces apoptosis in endothelial cells. In addition, RGCC was the most up-regulated choriocapillaris gene in a donor diagnosed with AMD. These results provide a characterization of the human RPE and choriocapillaris transcriptome, offering potential insight into the mechanisms of choriocapillaris response to complement injury and choroidal vascular disease in age-related macular degeneration.
Anisotropic flow coefficients beyond triangular flow receive important contributions from lower-order harmonics through nonlinear coupling. We present a theoretical framework which allows one to ...quantify the contribution induced by such nonlinear coupling to any flow harmonic of any order. We show the effectiveness of this formalism through an application to hexagonal flow, V6. We study, in particular, the coupling of V6 to triangular flow, V3, in Pb+Pb collisions at s=2.76TeV, using both Large Hadron Collider data and event-by-event hydrodynamic calculations.
We present results from numerical simulations of the acceleration of solar energetic particles (SEPs) associated with strong, fast, and radially propagating interplanetary shocks. We focus on the ...phase of the SEP event at the time of the shock passage at 1 AU, which is when the peak intensity at energies below a few MeV is the highest. The shocks in our study start between 2 and 10 solar radii and propagate beyond 1 AU. We study the effect of various shock and particle input parameters, such as the spatial diffusion coefficient, shock speed, solar wind speed, initial location of the shock, and shock deceleration rate, on the total integrated differential intensity, I, of SEPs with kinetic energies > 10 MeV. I is the integral over energy of the differential intensity spectrum at the time of the shock passage at 1 AU. We find that relatively small changes in the parameters can lead to significant event-to-event changes in I. For example, a factor of 2 increase in the diffusion coefficient at a given energy and spatial location, can lead to a decrease in I by as much as a factor of 50. This may help explain why there are fewer large SEP events seen during the current solar maximum compared to previous maxima. It is known that the magnitude of the interplanetary magnetic field is noticeably weaker this solar cycle than it was in the previous cycle and this will naturally lead to a somewhat larger diffusion coefficient of SEPs.
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