525 research outputs found
The XMM-LSS survey: the Class 1 cluster sample over the extended 11 deg and its spatial distribution
This paper presents 52 X-ray bright galaxy clusters selected within the 11
deg XMM-LSS survey. 51 of them have spectroscopic redshifts
(), one is identified at , and all together make
the high-purity "Class 1" (C1) cluster sample of the XMM-LSS, the highest
density sample of X-ray selected clusters with a monitored selection function.
Their X-ray fluxes, averaged gas temperatures (median keV),
luminosities (median ergs/s) and total mass
estimates (median ) are measured, adapting to
the specific signal-to-noise regime of XMM-LSS observations. The redshift
distribution of clusters shows a deficit of sources when compared to the
cosmological expectations, regardless of whether WMAP-9 or Planck-2013 CMB
parameters are assumed. This lack of sources is particularly noticeable at . However, after quantifying uncertainties due to small
number statistics and sample variance we are not able to put firm (i.e. ) constraints on the presence of a large void in the cluster
distribution. We work out alternative hypotheses and demonstrate that a
negative redshift evolution in the normalization of the relation
(with respect to a self-similar evolution) is a plausible explanation for the
observed deficit. We confirm this evolutionary trend by directly studying how
C1 clusters populate the space, properly accounting for selection
biases. We point out that a systematically evolving, unresolved, central
component in clusters and groups (AGN contamination or cool core) can impact
the classification as extended sources and be partly responsible for the
observed redshift distribution.[abridged]Comment: 33 pages, 21 figures, 3 tables ; accepted for publication in MNRA
An improved method of supercharged transposed latissimus dorsi flap with the skin paddle for the management of a complicated lumbosacral defect
OBJECTIVE: Treatment of nonhealing wounds of lower back often poses a powerful challenge. We present one of the first
report of treatment of a lumbosacral defect with a supercharged latissimus dorsi flap with the skin paddle.
CASE REPORT: We report a case of a 59 yearold man with myeloma of the sacral spine who underwent radiotherapy and chemotherapy and subsequently, laminectomies and placement of hardware for ongoing paresis and spine instability. Then, he developed an open wound and osteomyelitis of the spine with culture positive tuberculous granulomas. After multiple surgical debridement, he presented to our service and was treated with a single stage debridement followed by the performance of a latissimus dorsi musculocutaneous flap based on paraspinal perforators and supercharged.
RESULTS: This solution, allowed for augmentation of blood flow to the muscle with the inferior gluteal artery, provided coverage of the defect resistant to the pressure, and simplified post-operative management of the patient.
CONCLUSIONS: Alternative treatment options, including free tissue transfer, posed difficulties in finding suitable recipient vessels near the defect, in inserting the flap so as to restore its original length without compromising blood flow, and in postoperative care of the patient. Treatment of a lumbosacral defect with a supercharged latissimus dorsi flap with the skin paddle may represent a milestone procedure for complicated lower spine wounds
The XXL Survey X: K-band luminosity - weak-lensing mass relation for groups and clusters of galaxies
We present the K-band luminosity-halo mass relation, ,
for a subsample of 20 of the 100 brightest clusters in the XXL Survey observed
with WIRCam at the Canada-France-Hawaii Telescope (CFHT). For the first time,
we have measured this relation via weak-lensing analysis down to . This allows us to investigate whether the slope
of the relation is different for groups and clusters, as seen in other
works. The clusters in our sample span a wide range in mass, , at . The K-band luminosity
scales as with and an
intrinsic scatter of . Combining our
sample with some clusters in the Local Cluster Substructure Survey (LoCuSS)
present in the literature, we obtain a slope of and an
intrinsic scatter of . The flattening in the seen
in previous works is not seen here and might be a result of a bias in the mass
measurement due to assumptions on the dynamical state of the systems. We also
study the richness-mass relation and find that group-sized halos have more
galaxies per unit halo mass than massive clusters. However, the brightest
cluster galaxy (BCG) in low-mass systems contributes a greater fraction to the
total cluster light than BCGs do in massive clusters; the luminosity gap
between the two brightest galaxies is more prominent for group-sized halos.
This result is a natural outcome of the hierarchical growth of structures,
where massive galaxies form and gain mass within low-mass groups and are
ultimately accreted into more massive clusters to become either part of the BCG
or one of the brighter galaxies. [Abridged]Comment: A&A, in pres
Occurrence of White Grubs in Groundnut Crop in Uplands of South Vietnam: A New Report
Groundnut (Arachis hypogaea) is an important crop in
South Vietnam covering more than 125,000 ha under
different cropping systems. Crop surveys, and the onfarm
research organized in Trang Bang, Cuchi, Duc Hoa
and Go Dau during the past (until 2000), brought out the
importance of the foliage feeding insect pests (Spodoptera,
Helicoverpa) as economically important in farmers’ fields
(Ranga Rao 1995). Field visits during the last week of
May 2004 and interactions with the farmers in Tra Vinh
province, villages around Cau Ngang town revealed the
occurrence and importance of white grubs in this region.
This soil-inhabiting pest is a menace in this area, which is
in the heart of Mekong delta mostly covered by irrigated
rice (Oryza sativa) cultivation with multiple cropping
system
Assessment of Aspergillus flavus Infection and Aflatoxin Contamination in Groundnut in Southern Vietnam
Groundnut is an important food and cash crop in Vietnam with a high export potential. Limited studies of foods in the country have indicated that aflatoxin contamination is a problem in groundnut and maize. Vietnam considers the aflatoxin problem in groundnut to be of great importance, especially in view of Vietnam's expanding trade in this commodity, and the increasing use of groundnut cake as animal feed, Systematic surveys were conducted to assess Aspergillus flevus infection and aflatoxin contamination in groundnuts from farmers' fields and marketsloil mills in the major groundnut-growing areas of southern Vietnam. Results indicated that preharvest aflatoxin contamination is not likely to be a serious problem in adequately irrigated groundnuts. However, groundnuts grown under residual moisture or limited irrigation can be contaminated under conducive environmental conditions prevailing in the winter-spring season as evidenced by moderate to high aflatoxin levels found in some samples. Soilborne diseases such as stemlpod rot and bacterial wilt prevalent in many parts of southern Vietnam are likely to encourage A. flavus invasion of podlseed in the field. It is emphasized that the aflatoxin problem should be viewed holistically as contamination can be pre- and postharvest with many factors influencing, e,g., the crop rotation, soil moisture, soilborne pests and diseases, crop produce drying and storage conditions. A brochure on "Aflatoxin contamination problems in groundnuts and groundnut products" was prepared (in English and Vietnamese) and distributed to many farmers, traders, and extension and research workers to enhance awareness of the aflatoxin problem and management option
Antagonism of the proinflammatory and pronociceptive actions of canonical and biased agonists of protease-activated receptor-2
Diverse proteases cleave protease-activated receptor-2 (PAR2) on primary sensory neurons and epithelial cells to evoke pain and inflammation. Trypsin and tryptase activate PAR2 by a canonical mechanism that entails cleavage within the extracellular N-terminus revealing a tethered ligand that activates the cleaved receptor. Cathepsin-S and elastase are biased agonists that cleave PAR2 at different sites to activate distinct signalling pathways. Although PAR2 is a therapeutic target for inflammatory and painful diseases, the divergent mechanisms of proteolytic activation complicate the development of therapeutically useful antagonists
An improved method of supercharged transposed latissimus dorsi flap with the skin paddle for the management of a complicated lumbosacral defect
OBJECTIVE:
Treatment of non-healing wounds of lower back often poses a powerful challenge. We present one of the first report of treatment of a lumbosacral defect with a supercharged latissimus dorsi flap with the skin paddle.
CASE REPORT:
We report a case of a 59 year-old man with myeloma of the sacral spine who underwent radiotherapy and chemotherapy and subsequently, laminectomies and placement of hardware for ongoing paresis and spine instability. Then, he developed an open wound and osteomyelitis of the spine with culture positive tuberculous granulomas. After multiple surgical debridement, he presented to our service and was treated with a single stage debridement followed by the performance of a latissimus dorsi musculocutaneous flap based on paraspinal perforators and supercharged.
RESULTS:
This solution, allowed for augmentation of blood flow to the muscle with the inferior gluteal artery, provided coverage of the defect resistant to the pressure, and simplified post-operative management of the patient.
CONCLUSIONS:
Alternative treatment options, including free tissue transfer, posed difficulties in finding suitable recipient vessels near the defect, in inserting the flap so as to restore its original length without compromising blood flow, and in postoperative care of the patient. Treatment of a lumbosacral defect with a supercharged latissimus dorsi flap with the skin paddle may represent a milestone procedure for complicated lower spine wounds
The Physics of Cluster Mergers
Clusters of galaxies generally form by the gravitational merger of smaller
clusters and groups. Major cluster mergers are the most energetic events in the
Universe since the Big Bang. Some of the basic physical properties of mergers
will be discussed, with an emphasis on simple analytic arguments rather than
numerical simulations. Semi-analytic estimates of merger rates are reviewed,
and a simple treatment of the kinematics of binary mergers is given. Mergers
drive shocks into the intracluster medium, and these shocks heat the gas and
should also accelerate nonthermal relativistic particles. X-ray observations of
shocks can be used to determine the geometry and kinematics of the merger. Many
clusters contain cooling flow cores; the hydrodynamical interactions of these
cores with the hotter, less dense gas during mergers are discussed. As a result
of particle acceleration in shocks, clusters of galaxies should contain very
large populations of relativistic electrons and ions. Electrons with Lorentz
factors gamma~300 (energies E = gamma m_e c^2 ~ 150 MeV) are expected to be
particularly common. Observations and models for the radio, extreme
ultraviolet, hard X-ray, and gamma-ray emission from nonthermal particles
accelerated in these mergers are described.Comment: 38 pages with 9 embedded Postscript figures. To appear in Merging
Processes in Clusters of Galaxies, edited by L. Feretti, I. M. Gioia, and G.
Giovannini (Dordrecht: Kluwer), in press (2001
ADI splitting schemes for a fourth-order nonlinear partial differential equation from image processing
We present directional operator splitting schemes for the numerical solution of a fourth-order, nonlinear partial differential evolution equation which arises in image processing. This equation constitutes the H−1-gradient flow of the total variation and represents a prototype of higher-order equations of similar type which are popular in imaging for denoising, deblurring and inpainting problems. The efficient numerical solution of this equation is very challenging due to the stiffness of most numerical schemes. We show that the combination of directional splitting schemes with implicit time-stepping provides a stable and computationally cheap numerical realisation of the equation
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