Blockade of adenosine A2A receptors prevents protein phosphorylation in the striatum induced by cortical stimulation

©2006 Society for NeurosciencePrevious studies have shown that cortical stimulation selectively activates extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation and immediate early gene expression in striatal GABAergic enkephalinergic neurons. In the present study, we demonstrate that blockade of adenosine A2A receptors with caffeine or a selective A2A receptor antagonist counteracts the striatal activation of cAMP– protein kinase A cascade (phosphorylation of the Ser845 residue of the glutamate receptor 1 subunit of the AMPA receptor) and mitogenactivated protein kinase (ERK1/2 phosphorylation) induced by the in vivo stimulation of corticostriatal afferents. The results indicate that A2A receptors strongly modulate the efficacy of glutamatergic synapses on striatal enkephalinergic neurons.This work was supported by the Intramural Research Program of the National Institutes of Health, National Institute on Drug Abuse, Department of Health and Human Services

Dynamic Boundaries in Asymmetric Exclusion Processes

We investigate the dynamics of a one-dimensional asymmetric exclusion process with Langmuir kinetics and a fluctuating wall. At the left boundary, particles are injected onto the lattice; from there, the particles hop to the right. Along the lattice, particles can adsorb or desorb, and the right boundary is defined by a wall particle. The confining wall particle has intrinsic forward and backward hopping, a net leftward drift, and cannot desorb. Performing Monte Carlo simulations and using a moving-frame finite segment approach coupled to mean field theory, we find the parameter regimes in which the wall acquires a steady state position. In other regimes, the wall will either drift to the left and fall off the lattice at the injection site, or drift indefinitely to the right. Our results are discussed in the context of non-equilibrium phases of the system, fluctuating boundary layers, and particle densities in the lab frame versus the frame of the fluctuating wall.Comment: 13 page

Topology in Physics - A Perspective

This article, written in honor of Fritz Rohrlich, briefly surveys the role of topology in physics.Comment: 16pp, 2 figures included (encapsulated postscript

Application of Vacuum Salt Distillation Technology for the Removal of Fluoride and Chloride from Legacy Fissile Materials

Between September 2009 and January 2011, the Savannah River National Laboratory (SRNL) and the Savannah River Site (SRS) HB-Line Facility designed, developed, tested, and successfully deployed a production-scale system for the distillation of sodium chloride (NaCl) and potassium chloride (KCl) from plutonium oxide (PuO{sub 2}). Subsequent efforts adapted the vacuum salt distillation (VSD) technology for the removal of chloride and fluoride from less-volatile halide salts at the same process temperature and vacuum. Calcium chloride (CaCl{sub 2}), calcium fluoride (CaF{sub 2}), and plutonium fluoride (PuF{sub 3}) were of particular concern. To enable the use of the same operating conditions for the distillation process, SRNL employed in situ exchange reactions to convert the less-volatile halide salts to compounds that facilitated the distillation of halide without removal of plutonium. SRNL demonstrated the removal of halide from CaCl{sub 2}, CaF{sub 2} and PuF{sub 3} below 1000 C using VSD technology

Meridional variations of the springtime phytoplankton community in the Sargasso Sea

Meridional distributions of particle, pigment, optical, chemical and physical in situ oceanographic properties, as well as satellite-sensed sea-surface temperature and color imagery, are used to investigate phytoplankton community distributions and their relation to the near-surface water masses of the S bnargasso Sea. 0-H3059 Measurements were made during April of 1985 along a 1200 km transect on 70W (from 24N to 35N). The seasonal evolution of subtropical Mode water (18° water) is shown to be the primary factor controlling the spatial distribution and evolution of the phytoplankton community in the northern Sargasso Sea (31 to 35N). The springtime near-surface restratification of recently ventilated 18° water initiated a diatom-dominated phytoplankton bloom. As the bloom declined, the phytoplankton community evolved into a diverse assemblage. The consequences of these phytoplankton successions were observed both temporally and as spatial variations along the meridional section. South of the region of 18° water wintertime ventilation (south of 31N), phytoplankton concentrations were considerably less and appeared to be regulated by different processes than the northern region. In particular, influences of subtropical convergence fronts were observed. For the northern Sargasso Sea, the wintertime ventilation of 18° water is shown to be the primary new nutrient flux into the euphotic zone, comprising most of the expected annual new production for this region

NNLO phase space master integrals for two-to-one inclusive cross sections in dimensional regularization

We evaluate all phase space master integrals which are required for the total cross section of generic 2 -> 1 processes at NNLO as a series expansion in the dimensional regulator epsilon. Away from the limit of threshold production, our expansion includes one order higher than what has been available in the literature. At threshold, we provide expressions which are valid to all orders in terms of Gamma functions and hypergeometric functions. These results are a necessary ingredient for the renormalization and mass factorization of singularities in 2 -> 1 inclusive cross sections at NNNLO in QCD.Comment: 37 pages, plus 3 ancillary files containing analytic expressions in Maple forma

Dynamic Centrifuge Experiment on a Cantilever Retaining Wall

Seismic loads on a tall, cantilever retaining wall were studied using centrifuge modeling. An aluminum wall (55\u27 prototype) retaining dry, cohesionless backfill was subjected to two successive dynamic events. The backfill surface was horizontal and even with the top of the wall. The input motion was supplied via a servo-controlled, electro-hydraulic shake table. The input motion was roughly sinusoidal with peak horizontal accelerations of approximately 0.2g and 0.4g for the first and second dynamic events, respectively. The input motion frequency was 1 hz at prototype scale. Lateral earth pressures on the wall, wall displacement, and accelerations of the wall and backfill soil were measured. Pressure transducers were used to directly measure lateral earth pressures on the wall. The magnitudes of the lateral earth pressures were compared with values calculated using the Mononobe-Okabe method. Preliminary results indicate that calculated pressures are higher than the measured pressures

Submerged turbulence detection with optical satellites

During fall periods in 2002, 2003 and 2004 three major oceanographic expeditions were carried out in Mamala Bay, Hawaii. These were part of the RASP Remote Anthropogenic Sensing Program. Ikonos and Quickbird optical satellite images of sea surface glint revealed ~100 m spectral anomalies in km^2 averaging patches in regions leading from the Honolulu Sand Island Municipal Outfall diffuser to distances up to 20 km. To determine the mechanisms behind this phenomenon, the RASP expeditions monitored the waters adjacent to the outfall with an array of hydrographic, optical and turbulence microstructure sensors in anomaly and ambient background regions. Drogue tracks and mean turbulence parameters for 2x10^4 microstructure patches were analyzed to understand complex turbulence, fossil turbulence and zombie turbulence near-vertical internal wave transport processes. The dominant mechanism appears to be generic to stratified natural fluids including planet and star atmospheres and is termed beamed zombie turbulence maser action (BZTMA). Most of the bottom turbulent kinetic energy is converted to ~100 m fossil turbulence waves. These activate secondary (zombie) turbulence in outfall fossil turbulence patches that transmit heat, mass, chemical species, momentum and information vertically to the sea surface for detection in an efficient maser action. The transport is beamed in intermittent mixing chimneys.Comment: 8 pages, 7 figures, SPIE Optics+Photonics 2007 Coastal Ocean Remote Sensing Aug. 27, San Diego, CA, see http://sdcc3.ucsd.edu/~ir11

The Formation and Evolution of Wide-orbit Stellar Multiples In Magnetized Clouds

Stars rarely form in isolation. Nearly half of the stars in the Milky Way have a companion, and this fraction increases in star-forming regions. However, why some dense cores and filaments form bound pairs while others form single stars remains unclear. We present a set of three-dimensional, gravo-magnetohydrodynamic simulations of turbulent star-forming clouds, aimed at understanding the formation and evolution of multiple-star systems formed through large-scale (greater than or similar to 10(3) au) turbulent fragmentation. We investigate three global magnetic field strengths, with global mass-to-flux ratios of mu(phi) = 2, 8, and 32. The initial separations of protostars in multiples depend on the global magnetic field strength, with stronger magnetic fields (e.g., mu(phi)= 2) suppressing fragmentation on smaller scales. The overall multiplicity fraction (MF) is between 0.4 and 0.6 for our strong and intermediate magnetic field strengths, which is in agreement with observations. The weak field case has a lower fraction. The MF is relatively constant throughout the simulations, even though stellar densities increase as collapse continues. While the MF rarely exceeds 60% in all three simulations, over 80% of all protostars are part of a binary system at some point. We additionally find that the distribution of binary spin misalignment angles is consistent with a randomized distribution. In all three simulations, several binaries originate with wide separations and dynamically evolve to less than or similar to 10(2) au separations. We show that a simple model of mass accretion and dynamical friction with the gas can explain this orbital evolution.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]