Geometric Effects on the Amplification of First Mode Instability Waves

The effects of geometric changes on the amplification of first mode instability waves in an external supersonic boundary layer were investigated using numerical techniques. Boundary layer stability was analyzed at Mach 6 conditions similar to freestream conditions obtained in quiet ground test facilities so that results obtained in this study may be applied to future test article design to measure first mode instability waves. The DAKOTA optimization software package was used to optimize an axisymmetric geometry to maximize the amplification of the waves at first mode frequencies as computed by the 2D STABL hypersonic boundary layer stability analysis tool. First, geometric parameters such as nose radius, cone half angle, vehicle length, and surface curvature were examined separately to determine the individual effects on the first mode amplification. Finally, all geometric parameters were allowed to vary to produce a shape optimized to maximize the amplification of first mode instability waves while minimizing the amplification of second mode instability waves. Since first mode waves are known to be most unstable in the form of oblique wave, the geometries were optimized using a broad range of wave frequencies as well as a wide range of oblique wave angles to determine the geometry that most amplifies the first mode waves. Since first mode waves are seen most often in flows with low Mach numbers at the edge of the boundary layer, the edge Mach number for each geometry was recorded to determine any relationship between edge Mach number and the stability of first mode waves. Results indicate that an axisymmetric cone with a sharp nose and a slight flare at the aft end under the Mach 6 freestream conditions used here will lower the Mach number at the edge of the boundary layer to less than 4, and the corresponding stability analysis showed maximum first mode N factors of 3

Global priorities for conservation across multiple dimensions of mammalian diversity

Conservation priorities that are based on species distribution, endemism, and vulnerability may underrepresent biologically unique species as well as their functional roles and evolutionary histories. To ensure that priorities are biologically comprehensive, multiple dimensions of diversity must be considered. Further, understanding how the different dimensions relate to one another spatially is important for conservation prioritization, but the relationship remains poorly understood. Here, we use spatial conservation planning to (i) identify and compare priority regions for global mammal conservation across three key dimensions of biodiversity-taxonomic, phylogenetic, and traits-and (ii) determine the overlap of these regions with the locations of threatened species and existing protected areas. We show that priority areas for mammal conservation exhibit low overlap across the three dimensions, highlighting the need for an integrative approach for biodiversity conservation. Additionally, currently protected areas poorly represent the three dimensions of mammalian biodiversity. We identify areas of high conservation priority among and across the dimensions that should receive special attention for expanding the global protected area network. These high-priority areas, combined with areas of high priority for other taxonomic groups and with social, economic, and political considerations, provide a biological foundation for future conservation planning efforts

Finite Size Effect on Correlation Functions of a Bose Gas in a Trap and Destruction of the Order Parameter by Phase Fluctuations

The influence of the finite sizes on the coherent properties of 3D Bose systems is considered. As is shown, the correlation functions of a Bose gas in a trap have essential differences from analogous correlation functions in an infinite system. Thus, the anomalous correlation function vanishes due to the divergency of phase fluctuations which destruct the order parameter too. The normal correlation function decays exponentially in time for sufficiently large time interval.Comment: 10 pages, RevTex4, some references have been added some changes in text are mad

Methodological Issues in Multistage Genome-Wide Association Studies

Because of the high cost of commercial genotyping chip technologies, many investigations have used a two-stage design for genome-wide association studies, using part of the sample for an initial discovery of ``promising'' SNPs at a less stringent significance level and the remainder in a joint analysis of just these SNPs using custom genotyping. Typical cost savings of about 50% are possible with this design to obtain comparable levels of overall type I error and power by using about half the sample for stage I and carrying about 0.1% of SNPs forward to the second stage, the optimal design depending primarily upon the ratio of costs per genotype for stages I and II. However, with the rapidly declining costs of the commercial panels, the generally low observed ORs of current studies, and many studies aiming to test multiple hypotheses and multiple endpoints, many investigators are abandoning the two-stage design in favor of simply genotyping all available subjects using a standard high-density panel. Concern is sometimes raised about the absence of a ``replication'' panel in this approach, as required by some high-profile journals, but it must be appreciated that the two-stage design is not a discovery/replication design but simply a more efficient design for discovery using a joint analysis of the data from both stages. Once a subset of highly-significant associations has been discovered, a truly independent ``exact replication'' study is needed in a similar population of the same promising SNPs using similar methods.Comment: Published in at http://dx.doi.org/10.1214/09-STS288 the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

Lasing and cooling in a hot cavity

We present a microscopic laser model for many atoms coupled to a single cavity mode, including the light forces resulting from atom-field momentum exchange. Within a semiclassical description, we solve the equations for atomic motion and internal dynamics to obtain analytic expressions for the optical potential and friction force seen by each atom. When optical gain is maximum at frequencies where the light field extracts kinetic energy from the atomic motion, the dynamics combines optical lasing and motional cooling. From the corresponding momentum diffusion coefficient we predict sub-Doppler temperatures in the stationary state. This generalizes the theory of cavity enhanced laser cooling to active cavity systems. We identify the gain induced reduction of the effective resonator linewidth as key origin for the faster cooling and lower temperatures, which implys that a bad cavity with a gain medium can replace a high-Q cavity. In addition, this shows the importance of light forces for gas lasers in the low-temperature limit, where atoms can arrange in a periodic pattern maximizing gain and counteracting spatial hole burning. Ultimately, in the low temperature limit, such a setup should allow to combine optical lasing and atom lasing in single device.Comment: 11 pages, 6 figure

Maternal six week postnatal check should assess for postnatal anxiety.

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Experimental Design for the Gemini Planet Imager

The Gemini Planet Imager (GPI) is a high performance adaptive optics system being designed and built for the Gemini Observatory. GPI is optimized for high contrast imaging, combining precise and accurate wavefront control, diffraction suppression, and a speckle-suppressing science camera with integral field and polarimetry capabilities. The primary science goal for GPI is the direct detection and characterization of young, Jovian-mass exoplanets. For plausible assumptions about the distribution of gas giant properties at large semi-major axes, GPI will be capable of detecting more than 10% of gas giants more massive than 0.5 M_J around stars younger than 100 Myr and nearer than 75 parsecs. For systems younger than 1 Gyr, gas giants more massive than 8 M_J and with semi-major axes greater than 15 AU are detected with completeness greater than 50%. A survey targeting young stars in the solar neighborhood will help determine the formation mechanism of gas giant planets by studying them at ages where planet brightness depends upon formation mechanism. Such a survey will also be sensitive to planets at semi-major axes comparable to the gas giants in our own solar system. In the simple, and idealized, situation in which planets formed by either the "hot-start" model of Burrows et al. (2003) or the core accretion model of Marley et al. (2007), a few tens of detected planets are sufficient to distinguish how planets form.Comment: 15 pages, 9 figures, revised after referee's comments and resubmitted to PAS

Reduction in jejunal fluid absorption in vivo through distension and cholinergic stimulation not attributable to enterocyte secretion

Jejunal fluid absorption in vivo was reduced by distension and by hydrostatic pressure and further declined on adding E. coli STa enterotoxin but no net fluid secretion was detected. Luminal atropine reduced pressure mediated reductions in fluid absorption to normal values but intravenous hexamethonium was without effect. A neural component to inhibition of absorption by pressure (though not stretch) may be mediated by axon reflexes within cholinergic neurons.Perfusion of cholinergic compounds also reduced net fluid absorption but did not cause secretion. In order to show that these actions were not secretory processes stimulated by cholinergic compounds that offset normal rates of absorption, these compounds were tested for their ability to cause net secretion in loops that were perfused with solutions in which choline substituted for sodium ion. In addition, these perfusates additionally contained E. coli STa enterotoxin or EIPA (ethyl-isopropyl-amiloride) to minimize absorption.In these circumstances, where it might be expected to do so if it were acting through a secretory rather than an absorptive mechanism, carbachol did not cause net fluid secretion. Cholinergic stimulation and pressure induced distension are thought to reduce net fluid absorption through inducing secretion but are found only to reduce fluid absorption.In conclusion, distension and cholinergic stimulation of the small intestine are two further circumstances in which fluid secretion is assumed to explain their action on fluid movement, as required by the enterocyte secretion model of secretion but, which like STa enterotoxin, instead are only able to reduce fluid absorption. This casts further doubt on the widespread validity of the enterocyte secretion model for fluid appearance in the lumen in diarrhoeal diseases

Implications for the origin of dwarf early-type galaxies: a detailed look at the isolated rotating dwarf early-type galaxy CG 611, with ramifications for the Fundamental Plane's (S_K)^2 kinematic scaling and the spin-ellipticity diagram

Selected from a sample of nine, isolated, dwarf early-type galaxies (ETGs) having the same range of kinematic properties as dwarf ETGs in clusters, we use CG 611 (LEDA 2108986) to address the Nature versus Nurture debate regarding the formation of dwarf ETGs. The presence of faint disk structures and rotation within some cluster dwarf ETGs has often been heralded as evidence that they were once late-type spiral or dwarf irregular galaxies prior to experiencing a cluster-induced transformation into an ETG. However, CG 611 also contains significant stellar rotation (~20 km/s) over its inner half light radius, R_(e,maj)=0.71 kpc, and its stellar structure and kinematics resemble those of cluster ETGs. In addition to hosting a faint young nuclear spiral within a possible intermediate-scale stellar disk, CG 611 has accreted an intermediate-scale, counter-rotating gas disk. It is therefore apparent that dwarf ETGs can be built by accretion events, as opposed to disk-stripping scenarios. We go on to discuss how both dwarf and ordinary ETGs with intermediate-scale disks, whether under (de)construction or not, are not fully represented by the kinematic scaling S_0.5=sqrt{ 0.5(V_rot)^2 + sigma^2 }, and we also introduce a modified spin-ellipticity diagram, lambda(R)-epsilon(R), with the potential to track galaxies with such disks.Comment: 15 pages (includes 9 figures and an extensive 2+ page reference list