859 research outputs found
Mass accretion rates of clusters of galaxies: CIRS and HeCS
We use a new spherical accretion recipe tested on N-body simulations to
measure the observed mass accretion rate (MAR) of 129 clusters in the Cluster
Infall Regions in the Sloan Digital Sky Survey (CIRS) and in the Hectospec
Cluster Survey (HeCS). The observed clusters cover the redshift range of
and the mass range of . Based on three-dimensional mass profiles of simulated
clusters reaching beyond the virial radius, our recipe returns MARs that agree
with MARs based on merger trees. We adopt this recipe to estimate the MAR of
real clusters based on measurements of the mass profile out to .
We use the caustic method to measure the mass profiles to these large radii. We
demonstrate the validity of our estimates by applying the same approach to a
set of mock redshift surveys of a sample of 2000 simulated clusters with a
median mass of as well as a sample
of 50 simulated clusters with a median mass of : the median MARs based on the caustic mass profiles of
the simulated clusters are unbiased and agree within with the median
MARs based on the real mass profile of the clusters. The MAR of the CIRS and
HeCS clusters increases with the mass and the redshift of the accreting
cluster, which is in excellent agreement with the growth of clusters in the
CDM model.Comment: 25 pages, 19 figures, 7 table
Digital Image Correlation analysis on the bone displacement during split crest: An ex vivo study
The split crest is an established surgical technique for horizontal bone augmentation.
It allows to place implants of adequate diameter in sites where the bone would be too thin for
the implantation. In this study, two split crest techniques (using threaded bone expanders or
ultrasonic bone surgery) were performed ex vivo on bovine ribs, and dental implants were then
inserted in the so prepared implantation sites. Digital image correlation was used to measure
the bone external surface displacement throughout the surgical procedures. Both techniques
provided an adequate bone volume for implant insertion, and no significant differences were
highlighted regarding the displacement. However, bone accidental fracture only occurred
during split crest with threaded bone expanders, suggesting differences in the internal strain
distribution induced by the two technique
Counter-propagating entangled photons from a waveguide with periodic nonlinearity
The conditions required for spontaneous parametric down-conversion in a
waveguide with periodic nonlinearity in the presence of an unguided pump field
are established. Control of the periodic nonlinearity and the physical
properties of the waveguide permits the quasi-phase matching equations that
describe counter-propagating guided signal and idler beams to be satisfied. We
compare the tuning curves and spectral properties of such counter-propagating
beams to those for co-propagating beams under typical experimental conditions.
We find that the counter-propagating beams exhibit narrow bandwidth permitting
the generation of quantum states that possess discrete-frequency entanglement.
Such states may be useful for experiments in quantum optics and technologies
that benefit from frequency entanglement.Comment: submitted to Phys. Rev.
The MURALES survey. I. A dual AGN in the radio galaxy 3C459?
We observed the FRII radio galaxy 3C459 (z=0.22) with the MUSE spectrograph
at the Very Large Telescope (VLT) as part of the MURALES project (a MUse RAdio
Loud Emission line Snapshot survey). We detected diffuse nuclear emission and a
filamentary ionized gas structure forming a one-sided, triangular-shaped region
extending out to 80 kpc. The central emission line region is dominated by
two compact knots of similar flux: the first (N1) cospatial with the radio core
and the (N2) second located 1.2" (5.3 kpc) to the SE. The two regions differ
dramatically from the point of view of velocity (with an offset of ~400 km/s),
line widths, and line ratios. This suggests that we are observing a dual AGN
system formed by a radio loud AGN and type 2 QSO companion, which is the result
of the recent merger that also produced its disturbed host morphology. The
alternative possibility that N2 is just a bright emission line knot resulting
from, for example, a jet-cloud interaction, is disfavored because of 1) the
presence of a high ionization bicone whose apex is located at N2; 2) the
observed narrow line widths; 3) its line luminosity (~10^42 erg s-1) typical of
luminous QSOs; and 4) its location, which is offset from the jet path. The
putative secondary AGN must be highly obscured, since we do not detect any
emission in the Chandra and infrared Hubble Space Telescope images.Comment: 6 pages, 6 figures, A&A in pres
Effectiveness of synthetic calcite doped with Fe-EDDHSA as a slow-release Fe source: In-vitro experiment on kiwifruit (Actinidia chinensis var. deliciosa) plants
Doped calcite (Fe-EDDHSA/CaCO3) was experimentally produced. The hypothesis of the present experiment is that, when roots get in contact with Fe-EDDHSA/CaCO3, the extrusion of H+ decreases the pH and dissolves calcite with subsequent release of Fe that becomes available for roots. The aim of the experiment was to determine whether doped calcite might represent a slow-release Fe source for in-vitro grown kiwifruit plantlets.
The root elongation media used in the experiment had pH 8.0 and differed from each other for Fe supply as follow: Control medium that contained complete Murashige and Skoog salt mixture, including FeSO4 and Na(2)EDTA; calcite medium enriched with Fe-EDDHSA/CaCO3 as the only Fe source; -Fe medium without Fe.
The absence of FeSO4 in the medium caused a reduction of plantlet growth. The final pH was higher with calcite medium than in control and -Fe. The addition of Fe-EDDHSA/CaCO3 increased Fe shoot concentration when compared with the -Fe medium. The data of the present experiment show the potential Fe slow release ability of Fe-EDDHSA/CaCO3; however, further investigation on Fe containing fertilizers should be conducted on potted plants to validate our result
Hospital factors and patient characteristics in the treatment of colorectal cancer: a population based study
BACKGROUND: The present study focuses on the analysis of social, clinical and hospital characteristics that can lead to disparities in the management and outcome of care. To that end, indicators of the quality of initial treatment delivered to newly-diagnosed colorectal cancer patients in a North-Western Region of Italy, were investigated using administrative data. METHODS: The cohort includes all incident colorectal cancer patients (Nâ=â24,187) selected by a validated algorithm from the Piedmont Hospital Discharge Record system over an 8-year period (2000â2007). Three indicators of quality of care in this population-based cohort were evaluated: the proportion of preoperative radiotherapy (RT) and of abdominoperineal (AP) resection in rectal cancer patients, and the proportion of postoperative in-hospital mortality in colorectal cancer patients. RESULTS: Among rectal cancers, older patients were less likely to have preoperative RT, and more likely to receive an AP resection compared to younger patients. The probability of undergoing preoperative RT and AP resection was reduced in females compared to males (odds ratio (OR) 0.77, 95% confidence interval (CI) 0.64-0.93 and OR 0.78, 95%CI 0.69-0.89, respectively). However, there was a trend of increasing RT over time (p for trend <0.01). The probability of undergoing AP resection was increased in less-educated patients and in hospitals with a low caseload. A higher risk of postoperative in-hospital mortality was found among colorectal cancer patients who were older, male, (female versus male OR 0.71, 95%CI 0.60-0.84), unmarried (OR 1.32, 95%CI 1.09-1.59) or with unknown marital status. CONCLUSIONS: The study provides evidence of the importance of social, clinical and hospital characteristics on the equity and quality of care in a Southern European country with an open-access public health care system
Distance Properties of Short LDPC Codes and their Impact on the BP, ML and Near-ML Decoding Performance
Parameters of LDPC codes, such as minimum distance, stopping distance,
stopping redundancy, girth of the Tanner graph, and their influence on the
frame error rate performance of the BP, ML and near-ML decoding over a BEC and
an AWGN channel are studied. Both random and structured LDPC codes are
considered. In particular, the BP decoding is applied to the code parity-check
matrices with an increasing number of redundant rows, and the convergence of
the performance to that of the ML decoding is analyzed. A comparison of the
simulated BP, ML, and near-ML performance with the improved theoretical bounds
on the error probability based on the exact weight spectrum coefficients and
the exact stopping size spectrum coefficients is presented. It is observed that
decoding performance very close to the ML decoding performance can be achieved
with a relatively small number of redundant rows for some codes, for both the
BEC and the AWGN channels
Convolutional LSTM Networks for Subcellular Localization of Proteins
Machine learning is widely used to analyze biological sequence data.
Non-sequential models such as SVMs or feed-forward neural networks are often
used although they have no natural way of handling sequences of varying length.
Recurrent neural networks such as the long short term memory (LSTM) model on
the other hand are designed to handle sequences. In this study we demonstrate
that LSTM networks predict the subcellular location of proteins given only the
protein sequence with high accuracy (0.902) outperforming current state of the
art algorithms. We further improve the performance by introducing convolutional
filters and experiment with an attention mechanism which lets the LSTM focus on
specific parts of the protein. Lastly we introduce new visualizations of both
the convolutional filters and the attention mechanisms and show how they can be
used to extract biological relevant knowledge from the LSTM networks
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