958 research outputs found
Weak Lensing Mass Reconstruction: Flexion vs Shear
Weak gravitational lensing has proven to be a powerful tool to map directly
the distribution of dark matter in the Universe. The technique, currently used,
relies on the accurate measurement of the gravitational shear that corresponds
to the first-order distortion of the background galaxy images. More recently, a
new technique has been introduced that relies on the accurate measurement of
the gravitational flexion that corresponds to the second-order distortion of
the background galaxy images. This technique should probe structures on smaller
scales than that of a shear analysis. The goal of this paper is to compare the
ability of shear and flexion to reconstruct the dark matter distribution by
taking into account the dispersion in shear and flexion measurements. Our
results show that the flexion is less sensitive than shear for constructing the
convergence maps on scales that are physically feasible for mapping, meaning
that flexion alone not be used to do convergence map reconstruction, even on
small scales.Comment: Submitted to Ap
Hawaii Deep Water Cable Program phase II-A : executive summary
This Executive Summary for the Hawaii Deep Water Cable (HDWC) Program summarizes the state-funded Phase II-A work that has been performed; indicates the interrelationships of the state- and federally-funded portions of the program: and identifies the major accomplishments of these efforts.Funding for the HDWC Program is being provided by the State of Hawaii (through the Department of Planning and Economic Development - DPRD) and the U.S. Department of Energy. All federally-funded activities are included in the designation Phase II. State-funded activities have been designated as II-A, II-B, and II-C to correspond with the 82-83, 83-84, and 84-85 fiscal years
Scale invariance of cell size fluctuations in starving bacteria
In stable environments, cell size fluctuations are thought to be governed by
simple physical principles, as suggested by recent findings of scaling
properties. Here, by developing a microfluidic device and using E. coli, we
investigate the response of cell size fluctuations against starvation. By
abruptly switching to non-nutritious medium, we find that the cell size
distribution changes but satisfies scale invariance: the rescaled distribution
is kept unchanged and determined by the growth condition before starvation.
These findings are underpinned by a model based on cell growth and cell cycle.
Further, we numerically determine the range of validity of the scale invariance
over various characteristic times of the starvation process, and find the
violation of the scale invariance for slow starvation. Our results, combined
with theoretical arguments, suggest the relevance of the multifork replication,
which helps retaining information of cell cycle states and may thus result in
the scale invariance.Comment: 15+23 pages, 5+11 figures and 2 table
Gravitational Flexion by Elliptical Dark Matter Haloes
We present equations for the gravitational lensing flexion expected for an
elliptical lens mass distribution. These can be reduced to one-dimensional
finite integrals, thus saving significant computing time over a full
two-dimensional calculation. We estimate constraints on galaxy halo
ellipticities for a range of potential future surveys, finding that the
constraints from the two different types of flexion are comparable and are up
to two orders of magnitude tighter than those from shear. Flexion therefore
appears to be a very promising potential tool for constraining the shapes of
galaxy haloes from future surveys.Comment: 7 pages, 5 figures, submitted to MNRA
Identificação de mecanismos envolvidos na resposta de bovinos ao carrapato Rhipicephalus microplus.
O objetivo desse trabalho foi identificar grupos de genes envolvidos na resposta de bovinos à infestação artificial com o carrapato Rhipicephalus microplus, por meio da construção de redes gênicas. Dados de um experimento com microarranjos, provenientes da hibridização de amostras de pele de fêmeas cruzadas Senepol x Nelore, Angus x Nelore e Nelore, obtidas antes (A) e (D) após a infestação artificial com o carrapato, foram analisados por meio de uma metodologia de construção de redes baseada em co-expressão gênica (WGCNA). Os dados foram pré-processados usando os pacotes affy e gcrma do R/Bioconductor e as redes de co-expressão identificadas separadamente para cada grupo (A e D), pelo pacote R/WGCNA. As redes foram comparadas e os módulos não conservados entre os dois grupos foram identificados a partir de um teste de correlação dos valores de conectividade. Nossa análise identificou 8 módulos de genes co-expressos, sendo um deles (6) não conservado entre os grupos. O modulo 6 (n=85 genes) mostrou-se enriquecido para o processo biológico Proteólise, sugerindo o envolvimento desse processo e dos genes identificados (ADAMTS4, CASP4, C3, CFB, PRSS22 e SPCS3) na resposta dos animais à infestação
Identificação de mecanismos envolvidos na resposta de bovinos ao carrapato Rhipicephalus microplus.
O objetivo desse trabalho foi identificar grupos de genes envolvidos na resposta de bovinos à infestação artificial com o carrapato Rhipicephalus microplus, por meio da construção de redes gênicas. Dados de um experimento com microarranjos, provenientes da hibridização de amostras de pele de fêmeas cruzadas Senepol x Nelore, Angus x Nelore e Nelore, obtidas antes (A) e (D) após a infestação artificial com o carrapato, foram analisados por meio de uma metodologia de construção de redes baseada em co-expressão gênica (WGCNA). Os dados foram pré-processados usando os pacotes affy e gcrma do R/Bioconductor e as redes de co-expressão identificadas separadamente para cada grupo (A e D), pelo pacote R/WGCNA. As redes foram comparadas e os módulos não conservados entre os dois grupos foram identificados a partir de um teste de correlação dos valores de conectividade. Nossa análise identificou 8 módulos de genes co-expressos, sendo um deles (6) não conservado entre os grupos. O modulo 6 (n=85 genes) mostrou-se enrique ido para o processo biológico Proteólise, sugerindo o envolvimento desse processo e dos genes identificados (ADAMTS4, CASP4, C3, CFB, PRSS22 e SPCS3) na resposta dos animais à infestação
Monodisperse macromolecules – A stepping stone to understanding industrial polymers
AbstractPolymers synthesized via anionic polymerization have proved important to our fundamental understanding of the processing, that is rheology and crystallisation, of bulk commodity polymers. The role of monodisperse hydrogenated polybutadienes as models for linear and branched polyethylene is examined. Systematic studies of the effects of long-chain branching, using well-defined “comb” materials have improved our understanding of how the number and length of branches affect the rheological properties and how these features impact on their crystallization behaviour. A combination of techniques including rheology, Small Angle X-ray Scattering (SAXS), and birefringence measurements have provided insight into role of linear long chains in the formation of oriented morphologies during the crystallization of hydrogenated polybutadiene blends of controlled polydispersity leading to the development of a quantitative model
A New Constraint on the Ly Fraction of UV Very Bright Galaxies at Redshift 7
We study the extent to which very bright (-23.0 < MUV < -21.75) Lyman-break
selected galaxies at redshifts z~7 display detectable Lya emission. To explore
this issue, we have obtained follow-up optical spectroscopy of 9 z~7 galaxies
from a parent sample of 24 z~7 galaxy candidates selected from the 1.65 sq.deg
COSMOS-UltraVISTA and SXDS-UDS survey fields using the latest near-infrared
public survey data, and new ultra-deep Subaru z'-band imaging (which we also
present and describe in this paper). Our spectroscopy has yielded only one
possible detection of Lya at z=7.168 with a rest-frame equivalent width EW_0 =
3.7 (+1.7/-1.1) Angstrom. The relative weakness of this line, combined with our
failure to detect Lya emission from the other spectroscopic targets allows us
to place a new upper limit on the prevalence of strong Lya emission at these
redshifts. For conservative calculation and to facilitate comparison with
previous studies at lower redshifts, we derive a 1-sigma upper limit on the
fraction of UV bright galaxies at z~7 that display EW_0 > 50 Angstrom, which we
estimate to be < 0.23. This result may indicate a weak trend where the fraction
of strong Lya emitters ceases to rise, and possibly falls between z~6 and z~7.
Our results also leave open the possibility that strong Lya may still be more
prevalent in the brightest galaxies in the reionization era than their fainter
counterparts. A larger spectroscopic sample of galaxies is required to derive a
more reliable constraint on the neutral hydrogen fraction at z~7 based on the
Lya fraction in the bright galaxies.Comment: 20 pages, 7 figures, accepted for publication in Ap
Unifying Color and Texture Transfer for Predictive Appearance Manipulation
International audienceRecent color transfer methods use local information to learn the transformation from a source to an exemplar image, and then transfer this appearance change to a target image. These solutions achieve very successful results for general mood changes, e.g., changing the appearance of an image from ``sunny'' to ``overcast''. However, such methods have a hard time creating new image content, such as leaves on a bare tree. Texture transfer, on the other hand, can synthesize such content but tends to destroy image structure. We propose the first algorithm that unifies color and texture transfer, outperforming both by leveraging their respective strengths. A key novelty in our approach resides in teasing apart appearance changes that can be modeled simply as changes in color versus those that require new image content to be generated. Our method starts with an analysis phase which evaluates the success of color transfer by comparing the exemplar with the source. This analysis then drives a selective, iterative texture transfer algorithm that simultaneously predicts the success of color transfer on the target and synthesizes new content where needed. We demonstrate our unified algorithm by transferring large temporal changes between photographs, such as change of season -- e.g., leaves on bare trees or piles of snow on a street -- and flooding
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