72 research outputs found
The Butcher--Oemler effect at z~0.35: a change in perspective
The present paper focuses on the much debated Butcher-Oemler effect: the
increase with redshift of the fraction of blue galaxies in clusters.
Considering a representative cluster sample made of seven group/clusters at
z~0.35, we have measured the blue fraction from the cluster core to the cluster
outskirts and the field mainly using wide field CTIO images. This sample
represents a random selection of a volume complete x-ray selected cluster
sample, selected so that there is no physical connection with the studied
quantity (blue fraction), to minimize observational biases. In order to
statistically assess the significance of the Butcher-Oemler effect, we
introduce the tools of Bayesian inference. Furthermore, we modified the blue
fraction definition in order to take into account the reduced age of the
universe at higher redshifts, because we should no longer attempt to reject an
unphysical universe in which the age of the Universe does depend on redshift,
whereas the age of its content does not. We measured the blue fraction from the
cluster center to the field and we find that the cluster affects the properties
of the galaxies up to two virial radii at z~0.35. Data suggest that during the
last 3 Gyrs no evolution of the blue fraction, from the cluster core to the
field value, is seen beyond the one needed to account for the varying age with
redshift of the Universe and of its content. The agreement of the radial
profiles of the blue fraction at z=0 and z~0.35 implies that the pattern infall
did not change over the last 3 Gyr, or, at least, its variation has no
observational effect on the studied quantity.Comment: MNRAS, in pres
Predictive Value of Alvarado Score and Ultrasound in the Diagnosis of Acute Appendicitis (A prospective study
Background: Acute appendicitis is the commonest non traumatic cause of acute abdominal pain that needs surgical management .Alvarado score and ultrasonographies are the most cost effective, easy and available aids for diagnosis. The aim of the study was determining the reliability of Alvarado score and ultrasound in the diagnosis of acute appendicitis.
Results: The study was applied with 100 cases with different types of abdominal pain at presentation with 51 males and 49 females .The sensitivity was97.3% ,specificity 90%, and accuracy 89 of combined usage of Alvarado score and U/S findings preoperatively.
Patients and method: A prospective non-interventional study including patients admitted with suggestive history with signs and symptoms of acute appendicitis to the surgical emergency ward of Baghdad teaching hospital from July 1st 2017 to Feb 10th 2018, Alvarado score calculated and ultrasonography done for each patient enrolled in this study, then to be followed for intraoperative findings.
Conclusions: Combined application of Alvarado score and U/S has sensitivity 94.1% ,specificity 90% and accuracy 89% . In our medical facility and emergency ward, acute appendicitis remains as one of the top acute abdominal emergencies needing surgery in patients presenting with atypical clinical finding. So diagnosis becomes difficult. So Alvarado score along with ultrasound findings are useful for increasing the reliability in emergency department for accurate diagnosis of acute appendicitis therefore there should be training for the use of U/S by emergency physician and general surgeon in the diagnosis of acute appendicitis in order to decrease the rate of negative appendectomies
Obscured and unobscured AGN populations in a hard-X-ray selected sample of the XMDS survey
Our goal is to probe the populations of obscured and unobscured AGN
investigating their optical-IR and X-ray properties as a function of X-ray
flux, luminosity and redshift within a hard X-ray selected sample of 136 X-ray
sources in the XMM Medium Deep Survey (XMDS) with wide multiwavelength
coverage. The XMDS area is covered with optical photometry from the VVDS and
CFHTLS surveys and infrared Spitzer data. Based on the X-ray luminosity and
X-ray to optical ratio, 132 sources are likely AGN, of which 122 have
unambiguous optical - IR identification. The observed optical and IR spectral
energy distributions of sources are fitted with AGN/galaxy templates in order
to classify them and compute photometric redshifts. 70% of the AGN are fitted
by a type 2 AGN or a star forming galaxy template and are grouped together in a
single class of ``optically obscured'' AGN. They have ``red'' optical colors
and generally show significant X-ray absorption from X-ray spectra or hardness
ratios (N cm). Sources with SEDs typical of type 1 AGN
have ``blue'' optical colors and exhibit X-ray absorption in about 30% of
cases. We performed a stacking analysis for obscured and type 1 AGN. The
stacked X-ray spectrum of obscured AGN is flatter than that of type 1 AGN and
has an average spectral slope of Gamma = 1.6. The subsample of objects fitted
by a galaxy template has an even harder stacked spectrum, with Gamma = 1.2 -
1.3. The obscured fraction is larger at lower fluxes, lower redshifts and lower
luminosities. X-ray absorption is less common than ``optical'' obscuration and
its incidence is nearly constant with redshift and luminosity. This implies
that X-ray absorption is not necessarily related to optical obscuration.Comment: 33 pages, 21 figures, accepted for publication in A&
Predictive values of risk factors in management of diabetic foot
Background: Outcome of management of patients with diabetic foot is difficult to predict. Assessment of variables in history , examination and investigations were analyzed with outcome of management and whether can be assigned as prognostic factors .
Methods: prospective study of 300 patients with diabetic foot in Baghdad teaching hospital during the period from April 2000 to March 2004,certain criteria was taken in history and examination, these were investigated and treated either by conservative procedure or amputation.
Results: most common age group was 50-59 years ( 33.3%). The male to female ratio was 2:1. Conservative debridement was performed in ( 60%) of patients while amputation was employed in (40%). amputation was performed in 604 in patient above 60 years and in(75%) of patients who had diabetic foot lesions for > 2 weeks,and in 90% of smokers for 10 years or more. Amputation was needed in (71%) in those who had history of previous ulceration and 72.5% of patients who had positive history of previous amputation. Amputation was needed in (88%) of those who had their temperature >38°C. in (91%) of patients who had diabetic foot lesion of Wagner grade>III and 91%. patients with X-ray findings of osteomyelitis.
Conclusions: Highly significant association was found between amputation with following variable , smokers > 10 years, patients with a temperature of > 38°C, Hypertension > 140/90 mmHg Wagner grade > III, white blood cell count of > 20,000/cc and positive foot X-ray findings. Slight significant association of amputation and the following variables: Age >60 years, duration of foot lesion >2 weeks, history of previous amputation, previous ulceration, negative pedal pulses, deformed feet and patients who had impaired normal vision
Spectral Energy Distributions of Hard X-ray selected AGNs in the XMDS Survey
We present the spectral energy distributions (SEDs) of a hard X-ray selected
sample. The sample contains 136 sources with F(2-10 keV)>10^-14 erg/cm^2/s and
132 are AGNs. The sources are detected in a 1 square degree area of the
XMM-Newton-Medium Deep Survey where optical data from the VVDS, CFHTLS surveys,
and infrared data from the SWIRE survey are available. Based on a SED fitting
technique we derive photometric redshifts with sigma(1+z)=0.11 and 6% of
outliers and identify AGN signatures in 83% of the objects. This fraction is
higher than derived when a spectroscopic classification is available. The
remaining 17+9-6% of AGNs shows star-forming galaxy SEDs (SF class). The
sources with AGN signatures are divided in two classes, AGN1 (33+6-1%) and AGN2
(50+6-11). The AGN1 and AGN2 classes include sources whose SEDs are fitted by
type 1 and type 2 AGN templates, respectively. On average, AGN1s show soft
X-ray spectra, consistent with being unabsorbed, while AGN2s and SFs show hard
X-ray spectra, consistent with being absorbed. The analysis of the average SEDs
as a function of X-ray luminosity shows a reddening of the IR SEDs, consistent
with a decreasing contribution from the host galaxy at higher luminosities. The
AGNs in the SF classes are likely obscured in the mid-infrared, as suggested by
their low L(3-20micron)/Lcorr(0.5-10 keV) ratios. We confirm the previously
found correlation for AGNs between the radio luminosity and the X-ray and the
mid-infrared luminosities. The X-ray-radio correlation can be used to identify
heavily absorbed AGNs. However, the estimated radio fluxes for the missing AGN
population responsible for the bulk of the background at E>10 keV are too faint
to be detected even in the deepest current radio surveys.Comment: Accepted for publication in Ap
The Brera Multi-scale Wavelet Chandra Survey. I. Serendipitous source catalogue
We present the BMW-Chandra source catalogue drawn from essentially all
Chandra ACIS-I pointed observations with an exposure time in excess of 10ks
public as of March 2003 (136 observations). Using the wavelet detection
algorithm developed by Lazzati et al. (1999) and Campana et al. (1999), which
can characterise both point-like and extended sources, we identified 21325
sources. Among them, 16758 are serendipitous, i.e. not associated with the
targets of the pointings, and do not require a non-automated analysis. This
makes our catalogue the largest compilation of Chandra sources to date. The
0.5--10 keV absorption corrected fluxes of these sources range from ~3E-16 to
9E-12 erg cm^-2 s^-1 with a median of 7E-15 erg cm^-2 s^-1. The catalogue
consists of count rates and relative errors in three energy bands (total,
0.5-7keV; soft, 0.5-2keV; and hard, 2-7keV), and source positions relative to
the highest signal-to-noise detection among the three bands. The wavelet
algorithm also provides an estimate of the extension of the source. We include
information drawn from the headers of the original files, as well, and
extracted source counts in four additional energy bands, SB1 (0.5-1keV), SB2
(1-2keV), HB1 (2-4keV), and HB2 (4-7keV). We computed the sky coverage for the
full catalogue and for a subset at high Galactic latitude (|b|> 20deg). The
complete catalogue provides a sky coverage in the soft band (0.5-2keV, S/N =3)
of ~8 deg^2 at a limiting flux of 1E-13 erg cm^-2 s^-1, and ~2 deg^2 at a
limiting flux of ~1E-15 erg cm^-2 s^-1.Comment: Accepted by A&A, Higher res. Figs 4 and 5 at
http://www.ifc.inaf.it/~romano/BMC/Docs/aapaper/9601f4.eps
http://www.ifc.inaf.it/~romano/BMC/Docs/aapaper/9601f5.eps, Catalog Web
pages: http://www.brera.inaf.it/BMC/bmc_home.html
http://www.ifc.inaf.it/~romano/BMC/bmc_home.html (Mirror
The XMM-LSS survey: The XMDS/VVDS 4 sigma catalogue
We present a first catalogue of X-ray sources resulting from the central area
of the XMM-LSS (Large Scale Structure survey). We describe the reduction
procedures and the database tools we developed and used to derive a well
defined catalogue of X-ray sources. The present catalogue is limited to a
sub-sample of 286 sources detected at 4 sigma in the 1 deg^2 area covered by
the photometric VVDS (VIRMOS VLT Deep Survey), which allows us to provide
optical and radio identifications. We also discuss the X-ray properties of a
larger X-ray sample of 536 sources detected at > 4 sigma in the full 3 deg^2
area of the XMM Medium Deep Survey (XMDS) independently of the optical
identification. We also derive the logN-logS relationship for a sample of more
than one thousand sources that we discuss in the context of other surveys at
similar fluxes.Comment: 15+6 pages, 12 figures, accepted for publication in Astronomy &
Astrophysics The online catalogue announced in the paper will be accessible
in about 2 weeks due to technical reasons Fig. 2 replaced with a low
resolution on
The XMM large scale structure survey: optical vs. X-ray classifications of active galactic nuclei and the unified scheme
Our goal is to characterize AGN populations by comparing their X-ray and
optical classifications. We present a sample of 99 spectroscopically identified
X-ray point sources in the XMM-LSS survey which are significantly detected in
the [2-10] keV band, and with more than 80 counts. We performed an X-ray
spectral analysis for all of these 99 X-ray sources. Introducing the fourfold
point correlation coefficient, we find only a mild correlation between the
X-ray and the optical classifications, as up to 30% of the sources have
differing X-ray and optical classifications: on one hand, 10% of the type 1
sources present broad emission lines in their optical spectra and strong
absorption in the X-rays. These objects are highly luminous AGN lying at high
redshift and thus dilution effects are totally ruled out, their discrepant
nature being an intrinsic property. Their X-ray luminosities and redshifts
distributions are consistent with those of the unabsorbed X-ray sources with
broad emission lines. On the other hand, 25/32 are moderate luminosity AGN,
which are both unabsorbed in the X-rays and only present narrow emission lines
in their optical spectra. The majority of them have an optical spectrum which
is representative of the host galaxy. We finally infer that dilution of the AGN
by the host galaxy seems to account for their nature. 5/25 have been defined as
Seyfert 2. In conclusion, most of these 32 discrepant cases can be accounted
for by the standard AGN unified scheme, as its predictions are not met for only
12% of the 99 X-ray sources. ABRIDGEDComment: 25 pages, 19 figures, Accepted for publication in A&
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