Magneto-Rayleigh-Taylor Instability: Theory and Simulation in Planar and Cylindrical Pulsed Power Targets.

Cylindrical liner implosions in the Magnetized Liner Inertial Fusion (MagLIF) concept are susceptible to the magneto-Rayleigh-Taylor instability (MRT). The danger of MRT enters in two phases, (1) during the main implosion, the outer surface of the liner is MRT unstable, and (2) during the short time period when the liner decelerates onto the hot fuel, the inner surface becomes unstable. Growth of MRT on the outer surface may also feedthrough, which may seed the inner surface leading to high MRT growth in the second phase. If MRT growth becomes large enough, confinement of the fuel is lost. To characterize MRT, we solve the linearized, ideal MHD equations in both planar and cylindrical geometries, including an axial magnetic field and the effects of sausage and kink modes. To evaluate our analytic growth rates, 1D HYDRA MHD simulations are used to generate realistic, evolving profiles (in density, pressure, and magnetic field) during the implosion. In general, the total instability growth rates in cylindrical geometry are larger than those in planar geometry. MRT and feedthrough are suppressed by strong magnetic field line bending (tension). We apply our analytic MRT growth rates to experiments on the Z-machine at Sandia National Laboratories. Analytic MRT growth rates for a typical magnetized MagLIF-like implosion show the kink mode to be the fastest growing early and very late in the liner implosion (during deceleration). Sophisticated 2D HYDRA simulations show that highly compressed axial magnetic fields can reduce the growth of perturbations at the fuel/liner interface during the implosion phase, enhancing the stability of the implosion. HYDRA 2D simulations also show that a non-uniform shock, driven from the liner exterior, can seed the liner interior, leading to substantial growth of instability far in excess of feedthrough. Large-scale perturbations on the liner interior may also feedout to the liner exterior when a shock wave interacts with the surface, which further destabilizes the liner. These effects are reduced when shock compression is minimized or significant perturbations are not present during shock compression. The feedthrough effects then dominate.PhDNuclear ScienceUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/113414/1/weisy_1.pd

Differential effects of calcium antagonist subclasses on markers of nephropathy progression

Differential effects of calcium antagonist subclasses on markers of nephropathy progression.BackgroundNumerous studies suggest that the dihydropyridine calcium antagonists (DCAs) and nondihydropyridine calcium antagonists (NDCAs) have differential antiproteinuric effects. Proteinuria reduction is a correlate of the progression of renal disease. In an earlier systematic review, calcium antagonists were shown as effective antihypertensive drugs, but there was uncertainty about their renal benefits in patients with proteinuria and renal insufficiency.MethodsA systematic review was conducted to assess the differential effects of DCAs and NDCAs on proteinuria in hypertensive adults with proteinuria, with or without diabetes, and to determine whether these differential effects translate into altered progression of nephropathy. Studies included in the review had to be randomized clinical trials with at least 6months of treatment, include a DCA or NDCA treatment arm, have one or more renal end points, and have been initiated after 1986. Summary data were extracted from 28 studies entered into two identical but separate databases, which were compared and evaluated by independent reviewers. The effects of each drug class on blood pressure (N = 1338) and proteinuria (N = 510) were assessed.ResultsAfter adjusting for sample size, study length, and baseline value, there were no statistically significant differences in the ability of either class of calcium antagonist to decrease blood pressure. The mean change in proteinuria was +2% for DCAs and -30% for NDCAs (95% CI, 10% to 54%, P = 0.01). Consistently greater reductions in proteinuria were associated with the use of NDCAs compared with DCAs, despite no significant differences in blood pressure reduction or presence of diabetes.ConclusionThis analysis supports (1) similar efficacy between subclasses of calcium antagonists to lower blood pressure, and (2) greater reductions in proteinuria by NDCAs compared to DCAs in the presence or absence of diabetes. Based on these findings, NDCAs, alone or in combination with an angiotensin-converting enzyme (ACE) inhibitor or an angiotensin receptor blocker (ARB), are suggested as preferred agents to lower blood pressure in hypertensive patients with nephropathy associated with proteinuria

Багатомовність в Україні та її специфіка

У статті висвітлюються аспекти явища багатомовності, характерні для України як для національної держави, котра продовжує перебувати на стадії трансформації державно-політичної, соціально-економічної, духовної систем. Підкреслюється актуальність «аксіоми національної державності», згідно з якою українська мова, яка є рідною для більшості членів титульної нації країни, має бути єдиною державною мовою.The article studies the aspects of the phenomenon of multilingualism which are characteristic of Ukraine as a national state that remains at the stage of final forming complicated by the transformation of state political, social, economic and spiritual systems. The author underlines actuality of “the axiom of national statehood” that expects Ukrainian to be official language because it is native for the most of members of a titular nation in Ukraine

ArborZ: Photometric Redshifts Using Boosted Decision Trees

Precision photometric redshifts will be essential for extracting cosmological parameters from the next generation of wide-area imaging surveys. In this paper we introduce a photometric redshift algorithm, ArborZ, based on the machine-learning technique of Boosted Decision Trees. We study the algorithm using galaxies from the Sloan Digital Sky Survey and from mock catalogs intended to simulate both the SDSS and the upcoming Dark Energy Survey. We show that it improves upon the performance of existing algorithms. Moreover, the method naturally leads to the reconstruction of a full probability density function (PDF) for the photometric redshift of each galaxy, not merely a single "best estimate" and error, and also provides a photo-z quality figure-of-merit for each galaxy that can be used to reject outliers. We show that the stacked PDFs yield a more accurate reconstruction of the redshift distribution N(z). We discuss limitations of the current algorithm and ideas for future work.Comment: 10 pages, 13 figures, submitted to Ap

Recommended Priorities for Research on Ecological Impacts of Ocean and Coastal Acidification in the U.S. Mid-Atlantic

The estuaries and continental shelf system of the United States Mid-Atlantic are subject to ocean acidification driven by atmospheric CO2, and coastal acidification caused by nearshore and land-sea interactions that include biological, chemical, and physical processes. These processes include freshwater and nutrient input from rivers and groundwater; tidally-driven outwelling of nutrients, inorganic carbon, alkalinity; high productivity and respiration; and hypoxia. Hence, these complex dynamic systems exhibit substantial daily, seasonal, and interannual variability that is not well captured by current acidification research on Mid-Atlantic organisms and ecosystems. We present recommendations for research priorities that target better understanding of the ecological impacts of acidification in the U. S. Mid-Atlantic region. Suggested priorities are: 1) Determining the impact of multiple stressors on our resource species as well as the magnitude of acidification; 2) Filling information gaps on major taxa and regionally important species in different life stages to improve understanding of their response to variable temporal scales and sources of acidification; 3) Improving experimental approaches to incorporate realistic environmental variability and gradients, include interactions with other environmental stressors, increase transferability to other systems or organisms, and evaluate community and ecosystem response; 4) Determining the capacity of important species to acclimate or adapt to changing ocean conditions; 5) Considering multi-disciplinary, ecosystem-level research that examines acidification impacts on biodiversity and biotic interactions; and 6) Connecting potential acidification-induced ecological impacts to ecosystem services and the economy. These recommendations, while developed for the Mid-Atlantic, can be applicable to other regions will help align research towards knowledge of potential larger-scale ecological and economic impacts

Zebrafish type I collagen mutants faithfully recapitulate human type I collagenopathies

The type I collagenopathies are a group of heterogeneous connective tissue disorders, that are caused by mutations in the genes encoding type I collagen and include specific forms of osteogenesis imperfecta (OI) and the Ehlers-Danlos syndrome (EDS). These disorders present with a broad disease spectrum and large clinical variability of which the underlying genetic basis is still poorly understood. In this study, we systematically analyzed skeletal phenotypes in a large set of zebrafish, with diverse mutations in the genes encoding type I collagen, representing different genetic forms of human OI, and a zebrafish model resembling human EDS, which harbors a number of soft connective tissues defects, typical of EDS. Furthermore, we provide insight into how zebrafish and human type I collagen are compositionally and functionally related, which is relevant in the interpretation of human type I collagen-related disease models. Our studies reveal a high degree of intergenotype variability in phenotypic expressivity that closely correlates with associated OI severity. Furthermore, we demonstrate the potential for select mutations to give rise to phenotypic variability, mirroring the clinical variability associated with human disease pathology. Therefore, our work suggests the future potential for zebrafish to aid in identifying unknown genetic modifiers and mechanisms underlying the phenotypic variability in OI and related disorders. This will improve diagnostic strategies and enable the discovery of new targetable pathways for pharmacological intervention

Stellar, Brown Dwarf, and Multiple Star Properties from Hydrodynamical Simulations of Star Cluster Formation

We report the statistical properties of stars, brown dwarfs and multiple systems obtained from the largest hydrodynamical simulation of star cluster formation to date that resolves masses down to the opacity limit for fragmentation (a few Jupiter masses). The simulation is essentially identical to that of Bate, Bonnell & Bromm except that the initial molecular cloud is larger and more massive. It produces more than 1250 stars and brown dwarfs, providing unprecedented statistical information that can be compared with observational surveys. We find that hydrodynamical/sink particle simulations can reproduce many of the observed stellar properties very well. Binarity as a function of primary mass, the frequency of very-low-mass (VLM) binaries, general trends for the separation and mass ratio distributions of binaries, and the relative orbital orientations of triples systems are all in reasonable agreement with observations. We also examine the radial variations of binarity, velocity dispersion, and mass function in the resulting stellar cluster and the distributions of disc truncation radii due to dynamical interactions. For VLM binaries, we find that their frequency when using small accretion radii and gravitational softening is similar to that expected from observational surveys (approximately 20 percent). We also find that VLM binaries evolve from wide, unequal-mass systems towards close equal-mass systems as they form. The two main deficiencies of the calculations are that they over produce brown dwarfs relative to stars and that there are too few unequal mass binaries with K and G-dwarf primaries. [Abridged]Comment: Accepted by MNRAS, 28 pages, 26 figures. Animations available at http://www.astro.ex.ac.uk/people/mbate