703 research outputs found
Venous pseudo-aneurysm as a late complication of short-term central venous catheterisation
Complications following central venous catheterisation abound in the medical literature. This reflects the under-estimated potential hazards associated with this procedure as well as an increase in the number of such procedures performed in high-risk patients. We report on a case where a venous pseudo-aneurysm developed four months after the removal of a short-term central venous catheter in a moderately high-risk patient
Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy Improves Survival of Patients with Peritoneal Carcinomatosis from Gastric Cancer: Final Results of a Phase III Randomized Clinical Trial
The atmospheric parameters and spectral interpolator for the stars of MILES
Context. Empirical libraries of stellar spectra are used for stellar
classification and synthesis of stellar populations. MILES is a medium
spectral-resolution library in the optical domain covering a wide range of
temperatures, surface gravities and metallicities. Aims. We re-determine the
atmospheric parameters of these stars in order to improve the homogeneity and
accuracy. We build an interpolating function that returns a spectrum as a
function of the three atmospheric parameters, and finally, we characterize the
precision of the wavelength calibration and stability of the spectral
resolution. Methods. We use the ULySS program with the ELODIE library as a
reference and compare the results with literature compilations. Results. We
obtain precisions of 60 K, 0.13 and 0.05 dex respectively for Teff, log g and
[Fe/H] for the FGK stars. For the M stars, the mean errors are 38 K, 0.26 and
0.12 dex, and for the OBA 3.5%, 0.17 and 0.13 dex. We construct an interpolator
that we test against the MILES stars themselves. We test it also by measuring
the atmospheric parameters of the CFLIB stars with MILES as reference and find
it to be more reliable than the ELODIE interpolator for the evolved hot stars,
like in particular those of the blue horizontal branch.Comment: A&A accepted, 29 pages, 6 figure
Recommended from our members
How predation and landscape fragmentation affect vole population dynamics
Background: Microtine species in Fennoscandia display a distinct north-south gradient from regular cycles to stable
populations. The gradient has often been attributed to changes in the interactions between microtines and their predators.
Although the spatial structure of the environment is known to influence predator-prey dynamics of a wide range of species,
it has scarcely been considered in relation to the Fennoscandian gradient. Furthermore, the length of microtine breeding
season also displays a north-south gradient. However, little consideration has been given to its role in shaping or generating
population cycles. Because these factors covary along the gradient it is difficult to distinguish their effects experimentally in
the field. The distinction is here attempted using realistic agent-based modelling.
Methodology/Principal Findings: By using a spatially explicit computer simulation model based on behavioural and
ecological data from the field vole (Microtus agrestis), we generated a number of repeated time series of vole densities
whose mean population size and amplitude were measured. Subsequently, these time series were subjected to statistical
autoregressive modelling, to investigate the effects on vole population dynamics of making predators more specialised, of
altering the breeding season, and increasing the level of habitat fragmentation. We found that fragmentation as well as the
presence of specialist predators are necessary for the occurrence of population cycles. Habitat fragmentation and predator
assembly jointly determined cycle length and amplitude. Length of vole breeding season had little impact on the
oscillations.
Significance: There is good agreement between our results and the experimental work from Fennoscandia, but our results
allow distinction of causation that is hard to unravel in field experiments. We hope our results will help understand the
reasons for cycle gradients observed in other areas. Our results clearly demonstrate the importance of landscape
fragmentation for population cycling and we recommend that the degree of fragmentation be more fully considered in
future analyses of vole dynamics
A tetragonal-to-monoclinic phase transition in a ferroelectric perovskite: the structure of PbZr(0.52)Ti(0.48)O3
The perovskite-like ferroelectric system PbZr(1-x)Ti(x)O3 (PZT) has a nearly
vertical morphotropic phase boundary (MPB) around x=0.45-0.50. Recent
synchrotron x-ray powder diffraction measurements by Noheda et al. [Appl. Phys.
Lett. 74, 2059 (1999)] have revealed a new monoclinic phase between the
previously-established tetragonal and rhombohedral regions. In the present work
we describe a Rietveld analysis of the detailed structure of the tetragonal and
monoclinic PZT phases on a sample with x= 0.48 for which the lattice parameters
are respectively: at= 4.044 A, ct= 4.138 A, at 325 K, and am= 5.721 A, bm=
5.708 A, cm= 4.138 A, beta= 90.496 deg., at 20K. In the tetragonal phase the
shifts of the atoms along the polar [001] direction are similar to those in
PbTiO3 but the refinement indicates that there are, in addition, local
disordered shifts of the Pb atoms of ~0.2 A perpendicular to the polar axis..
The monoclinic structure can be viewed as a condensation along one of the
directions of the local displacements present in the tetragonal phase. It
equally well corresponds to a freezing-out of the local displacements along one
of the directions recently reported by Corker et al.[J. Phys. Condens.
Matter 10, 6251 (1998)] for rhombohedral PZT. The monoclinic structure
therefore provides a microscopic picture of the MPB region in which one of the
"locally" monoclinic phases in the "average" rhombohedral or tetragonal
structures freezes out, and thus represents a bridge between these two phases.Comment: REVTeX, 7 figures. Modifications after referee's suggestion: new
figure (figure 5), comments in 2nd para. (Sect.III) and in 2nd & 3rd para.
(Sect. IV-a), in the abstract: "...of ~0.2 A perpendicular to the polar
axis.
Level and course of FEV1 in relation to polymorphisms in NFE2L2 and KEAP1 in the general population
<p>Abstract</p> <p>Background</p> <p>The metabolism of xenobiotics plays an essential role in smoking related lung function loss and development of Chronic Obstructive Pulmonary Disease. Nuclear Factor Erythroid 2-Like 2 (NFE2L2 or NRF2) and its cytosolic repressor Kelch-like ECH-associated protein-1 (KEAP1) regulate transcription of enzymes involved in cellular detoxification processes and <it>Nfe2l2</it>-deficient mice develop tobacco-induced emphysema. We assessed the impact of Single Nucleotide Polymorphisms (SNPs) in both genes on the level and longitudinal course of Forced Expiratory Volume in 1 second (FEV<sub>1</sub>) in the general population.</p> <p>Methods</p> <p>Five <it>NFE2L2 </it>and three <it>KEAP1 </it>tagging SNPs were genotyped in the population-based Doetinchem cohort (n = 1,152) and the independent Vlagtwedde-Vlaardingen cohort (n = 1,390). On average 3 FEV<sub>1 </sub>measurements during 3 surveys, respectively 7 FEV<sub>1 </sub>measurements during 8 surveys were present. Linear Mixed Effect models were used to test cross-sectional and longitudinal genetic effects on repeated FEV<sub>1 </sub>measurements.</p> <p>Results</p> <p>In the Vlagtwedde-Vlaardingen cohort SNP rs11085735 in <it>KEAP1 </it>was associated with a higher FEV<sub>1 </sub>level (p = 0.02 for an additive effect), and SNP rs2364723 in <it>NFE2L2 </it>was associated with a lower FEV<sub>1 </sub>level (p = 0.06). The associations were even more significant in the pooled cohort analysis. No significant association of <it>KEAP1 </it>or <it>NFE2L2 </it>SNPs with FEV<sub>1 </sub>decline was observed.</p> <p>Conclusion</p> <p>This is the first genetic study on variations in key antioxidant transcriptional regulators <it>KEAP1 </it>and <it>NFE2L2 </it>and lung function in a general population. It identified 2 SNPs in <it>NFE2L2 </it>and <it>KEAP1 </it>which affect the level of FEV<sub>1 </sub>in the general population. It additionally shows that <it>NFE2L2 </it>and <it>KEAP1 </it>variations are unlikely to play a role in the longitudinal course of FEV<sub>1 </sub>in the general population.</p
β1 Integrin-Mediated Adhesion Signalling Is Essential for Epidermal Progenitor Cell Expansion
Background: There is a major discrepancy between the in vitro and in vivo results regarding the role of b1 integrins in the maintenance of epidermal stem/progenitor cells. Studies of mice with skin-specific ablation of b1 integrins suggested that epidermis can form and be maintained in their absence, while in vitro data have shown a fundamental role for these adhesion receptors in stem/progenitor cell expansion and differentiation. Methodology/Principal Findings: To elucidate this discrepancy we generated hypomorphic mice expressing reduced b1 integrin levels on keratinocytes that developed similar, but less severe defects than mice with b1-deficient keratinocytes. Surprisingly we found that upon aging these abnormalities attenuated due to a rapid expansion of cells, which escaped or compensated for the down-regulation of b1 integrin expression. A similar phenomenon was observed in aged mice with a complete, skin-specific ablation of the b1 integrin gene, where cells that escaped Cre-mediated recombination repopulated the mutant skin in a very short time period. The expansion of b1 integrin expressing keratinocytes was even further accelerated in situations of increased keratinocyte proliferation such as wound healing. Conclusions/Significance: These data demonstrate that expression of b1 integrins is critically important for the expansion of epidermal progenitor cells to maintain epidermal homeostasis
Candidate microlensing events from M31 observations with the Loiano telescope
Microlensing observations towards M31 are a powerful tool for the study of
the dark matter population in the form of MACHOs both in the Galaxy and the M31
halos, a still unresolved issue, as well as for the analysis of the
characteristics of the M31 luminous populations. In this work we present the
second year results of our pixel lensing campaign carried out towards M31 using
the 152 cm Cassini telescope in Loiano. We have established an automatic
pipeline for the detection and the characterisation of microlensing variations.
We have carried out a complete simulation of the experiment and evaluated the
expected signal, including an analysis of the efficiency of our pipeline. As a
result, we select 1-2 candidate microlensing events (according to different
selection criteria). This output is in agreement with the expected rate of M31
self-lensing events. However, the statistics are still too low to draw
definitive conclusions on MACHO lensing.Comment: 12 pages, 6 figures, 5 tables - Accepted for publication in The
Astrophysical Journa
Hadron Energy Reconstruction for the ATLAS Calorimetry in the Framework of the Non-parametrical Method
This paper discusses hadron energy reconstruction for the ATLAS barrel
prototype combined calorimeter (consisting of a lead-liquid argon
electromagnetic part and an iron-scintillator hadronic part) in the framework
of the non-parametrical method. The non-parametrical method utilizes only the
known ratios and the electron calibration constants and does not require
the determination of any parameters by a minimization technique. Thus, this
technique lends itself to an easy use in a first level trigger. The
reconstructed mean values of the hadron energies are within of the
true values and the fractional energy resolution is . The value of the ratio
obtained for the electromagnetic compartment of the combined calorimeter is
and agrees with the prediction that for this
electromagnetic calorimeter. Results of a study of the longitudinal hadronic
shower development are also presented. The data have been taken in the H8 beam
line of the CERN SPS using pions of energies from 10 to 300 GeV.Comment: 33 pages, 13 figures, Will be published in NIM
- …