Dark matter voids in the SDSS galaxy survey

What do we know about voids in the dark matter distribution given the Sloan Digital Sky Survey (SDSS) and assuming the $\Lambda\mathrm{CDM}$ model? Recent application of the Bayesian inference algorithm BORG to the SDSS Data Release 7 main galaxy sample has generated detailed Eulerian and Lagrangian representations of the large-scale structure as well as the possibility to accurately quantify corresponding uncertainties. Building upon these results, we present constrained catalogs of voids in the Sloan volume, aiming at a physical representation of dark matter underdensities and at the alleviation of the problems due to sparsity and biasing on galaxy void catalogs. To do so, we generate data-constrained reconstructions of the presently observed large-scale structure using a fully non-linear gravitational model. We then find and analyze void candidates using the VIDE toolkit. Our methodology therefore predicts the properties of voids based on fusing prior information from simulations and data constraints. For usual void statistics (number function, ellipticity distribution and radial density profile), all the results obtained are in agreement with dark matter simulations. Our dark matter void candidates probe a deeper void hierarchy than voids directly based on the observed galaxies alone. The use of our catalogs therefore opens the way to high-precision void cosmology at the level of the dark matter field. We will make the void catalogs used in this work available at http://www.cosmicvoids.net.Comment: 15 pages, 6 figures, matches JCAP published version, void catalogs publicly available at http://www.cosmicvoids.ne

Gout

peer reviewedIn the presence of a clinical acute monoarthritis, a differential diagnosis has to be made between septic arthritis, gout and diffuse chondrocalcinosis. Gout comes from a purine nucleotide metabolism disorder leading to serum urate level elevation. This hyperuricemia can lead to the deposition of monosodium urate crystals in the joints, causing acute attacks. After long-term evolution, others tissues as the kidneys can be involved: it is chronic gout. The definite diagnosis is based on the presence of monosodium urate crystals in the joint fluid. The diagnosis of gout should prompt a search for associated medical conditions that may affect both urate levels and longevity. These include alcoholism, various nephropathies, myeloproliferative disorders, and hypertension

Design of a low-noise aeroacoustic wind tunnel facility at Brunel University

This paper represents the design principle of a quiet, low turbulence and moderately high speed aeroacoustic wind tunnel which was recently commissioned at Brunel University. A new hemi-anechoic chamber was purposely built to facilitate aeroacoustic measurements. The wind tunnel can achieve a maximum speed of about 80 ms-1. The turbulence intensity of the free jet in the potential core is between 0.1–0.2%. The noise characteristic of the aeroacoustic wind tunnel was validated by three case studies. All of which can demonstrate a very low background noise produced by the bare jet in comparison to the noise radiated from the cylinder rod/flat plate/airfoil in the air stream.The constructions of the aeroacoustic wind tunnel and the hemi-anechoic chamber are financially supported by the School of Engineering and Design at Brunel University

Latex-supported catalysts for the autoxidation of thiols. 1. Use of ionene-based macromonomers

2,4-Ionene was prepd. from 1,4-dibromobutane and N,N,N',N'-tetramethylethylenediamine, and then treated with (chloromethyl)styrene to give styryl-terminated macromonomer. The macromonomer was polymd. with styrene to give latexes that had high catalytic activity in the autoxidn. of 2-mercaptoethano

High-quality fully relaxed In0.65Ga0.35As layers grown on InP using the paramorphic approach

International audienceThin and thick fully relaxed In 0.65 Ga 0.35 As layers have been grown on InP substrates 0.81% misfit, with high structural and high optoelectronic quality at an operating wavelength of 2.0 m. Full relaxation is achieved, using the paramorphic approach, by growing the In 0.65 Ga 0.35 As layers lattice matched to an InAs 0.25 P 0.75 seed membrane of predetermined lattice parameter. The InAs 0.25 P 0.75 layer was originally grown pseudomorphically strained on the InP substrate before being separated and elastically relaxed using surface micromachining

Development of Lumped Element Kinetic Inductance Detectors for NIKA

Lumped-element kinetic inductance detectors(LEKIDs) have recently shown considerable promise as direct absorption mm-wavelength detectors for astronomical applications. One major research thrust within the N\'eel Iram Kids Array (NIKA) collaboration has been to investigate the suitability of these detectors for deployment at the 30-meter IRAM telescope located on Pico Veleta in Spain. Compared to microwave kinetic inductance detectors (MKID), using quarter wavelength resonators, the resonant circuit of a LEKID consists of a discrete inductance and capacitance coupled to a feedline. A high and constant current density distribution in the inductive part of these resonators makes them very sensitive. Due to only one metal layer on a silicon substrate, the fabrication is relatively easy. In order to optimize the LEKIDs for this application, we have recently probed a wide variety of individual resonator and array parameters through simulation and physical testing. This included determining the optimal feed-line coupling, pixel geometry, resonator distribution within an array (in order to minimize pixel cross-talk), and resonator frequency spacing. Based on these results, a 144-pixel Aluminum array was fabricated and tested in a dilution fridge with optical access, yielding an average optical NEP of ~2E-16 W/Hz^1/2 (best pixels showed NEP = 6E-17 W/Hz^1/2 under 4-8 pW loading per pixel). In October 2010 the second prototype of LEKIDs has been tested at the IRAM 30 m telescope. A new LEKID geometry for 2 polarizations will be presented. Also first optical measurements of a titanium nitride array will be discussed.Comment: 5 pages, 12 figures; ISSTT 2011 Worksho

Strong obstruction of the Berends-Burgers-van Dam spin-3 vertex

In the eighties, Berends, Burgers and van Dam (BBvD) found a nonabelian cubic vertex for self-interacting massless fields of spin three in flat spacetime. However, they also found that this deformation is inconsistent at higher order for any multiplet of spin-three fields. For arbitrary symmetric gauge fields, we severely constrain the possible nonabelian deformations of the gauge algebra and, using these results, prove that the BBvD obstruction cannot be cured by any means, even by introducing fields of spin higher (or lower) than three.Comment: 19 pages, no figur