47 research outputs found
The XMM-Newton wide-field survey in the COSMOS field: V. Angular Clustering of the X-ray Point Sources
We present the first results of the measurements of angular auto-correlation
functions (ACFs) of X-ray point sources detected in the XMM-Newton observations
of the 2 deg2 COSMOS field (XMM-COSMOS). A significant positive signals have
been detected in the 0.5-2 (SFT) band, in the angle range of 0.5-24 arcminutes,
while the positive signals were at the 2 and 3 sigma levels in the 2-4.5 (MED)
and 4.5-10 (UHD) keV bands respectively. Correctly taking integral constraints
into account is a major limitation in interpreting our results. With power-law
fits to the ACFs without the integral constraint term, we find correlation
lengths of theta_c=1.9+-0.3, 0.8+0.5-0.4 and 6+-2 arcseconds for the SFT, MED,
and UHD bands respectively for gamma=1.8. The inferred comoving correlation
lengths, also taking into account the bias by the source merging due to
XMM-Newton PSF, are 9.8+-0.7, 5.8+1.4-1.7 and 12+-2 h-1 Mpc at the effective
redshifts of 1.1, 0.9, and 0.6 for the SFT, MED, and UHD bands respectively. If
we include the integral constraint term in the fitting process,assuming that
the power-law extends to the scale length of the entire XMM-COSMOSfield, the
correlation lengths become larger by 20%-90%. Comparing the inferred rms
fluctuations of the spatial distribution of AGNs with those of the underlying
mass, the bias parameters of the X-ray source clustering at these effective
redshifts are in the range b(AGN)=1.5-4. (Edited to simple ascii.)Comment: 17 pages, 3 figures Accepted for Astrophysical Journal Supplement
series (COSMOS Special issue
A massive proto-cluster of galaxies at a redshift of z {\approx} 5.3
Massive clusters of galaxies have been found as early as 3.9 Billion years
(z=1.62) after the Big Bang containing stars that formed at even earlier
epochs. Cosmological simulations using the current cold dark matter paradigm
predict these systems should descend from "proto-clusters" - early
over-densities of massive galaxies that merge hierarchically to form a cluster.
These proto-cluster regions themselves are built-up hierarchically and so are
expected to contain extremely massive galaxies which can be observed as
luminous quasars and starbursts. However, observational evidence for this
scenario is sparse due to the fact that high-redshift proto-clusters are rare
and difficult to observe. Here we report a proto-cluster region 1 billion years
(z=5.3) after the Big Bang. This cluster of massive galaxies extends over >13
Mega-parsecs, contains a luminous quasar as well as a system rich in molecular
gas. These massive galaxies place a lower limit of >4x10^11 solar masses of
dark and luminous matter in this region consistent with that expected from
cosmological simulations for the earliest galaxy clusters.Comment: Accepted to Nature, 16 Pages, 6 figure
The demography and the evolution of heavily obscured AGN
Obscured AGN as a phase in the SMBH/host co-evolution or still consistent with a geometrical interpretation after 30 years from the discovery of polarized lines in NGC1068 or both?
Incomplete review of most recent results biased toward hard X-rays
Census in terms of accreted mass (Soltan argument)
Perspective
X-UDS: The Chandra Legacy Survey of the UKIDSS Ultra Deep Survey Field
We present the X-UDS survey, a set of wide and deep Chandra observations
of the Subaru-XMM Deep/UKIDSS Ultra Deep Survey (SXDS/UDS) field. The
survey consists of 25 observations that cover a total area of 0.33
deg(2). The observations are combined to provide a nominal depth of
similar to 600 ks in the central 100 arcmin(2) region of the field that
has been imaged with Hubble/WFC3 by the CANDELS survey and similar to
200 ks in the remainder of the field. In this paper, we outline the
survey's scientific goals, describe our observing strategy, and detail
our data reduction and point source detection algorithms. Our analysis
has resulted in a total of 868 band-merged point sources detected with a
false-positive Poisson probability of <1 x 10(-4). In addition, we
present the results of an X-ray spectral analysis and provide
best-fitting neutral hydrogen column densities, N-H, as well as a sample
of 51 Compton-thick active galactic nucleus candidates. Using this
sample, we find the intrinsic Compton-thick fraction to be 30%-35%
over a wide range in redshift (z = 0.1-3), suggesting the obscured
fraction does not evolve very strongly with epoch. However, if we assume
that the Compton-thick fraction is dependent on luminosity, as is seen
for Compton-thin sources, then our results are consistent with a rise in
the obscured fraction out to z similar to 3. Finally, an examination of
the host morphologies of our Compton-thick candidates shows a high
fraction of morphological disturbances, in agreement with our previous
results. All data products described in this paper are made available
via a public website
Measuring the free fall of antihydrogen
After the first production of cold antihydrogen by the ATHENA and ATRAP experiments ten years ago, new second-generation experiments are aimed at measuring the fundamental properties of this anti-atom. The goal of AEGIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) is to test the weak equivalence principle by studying the gravitational interaction between matter and antimatter with a pulsed, cold antihydrogen beam. The experiment is currently being assembled at CERN's Antiproton Decelerator. In AEGIS, antihydrogen will be produced by charge exchange of cold antiprotons with positronium excited to a high Rydberg state (n > 20). An antihydrogen beam will be produced by controlled acceleration in an electric-field gradient (Stark acceleration). The deflection of the horizontal beam due to its free fall in the gravitational field of the earth will be measured with a moire deflectometer. Initially, the gravitational acceleration will be determined to a precision of 1%, requiring the detection of about 105 antihydrogen atoms. In this paper, after a general description, the present status of the experiment will be reviewed
Descripción de una jornada educativo-sanitaria en un área vulnerable
El cambio climático influye favorablemente en la dispersiĂłn de distintas enfermedades transmisibles, zoonĂłticas y no zoonĂłticas. Realizar vigilancia y alertas tempranas, asĂ como acciones tendientes al diagnĂłstico, tratamiento y profilaxis, a fin de realizar su control, es indispensable para evitar la diseminaciĂłn de Ă©stas a otros sitios. Un área centinela[I2] , barrios El ZanjĂłn, Piria, Villa Ruben Sito, El Molino e Isla RĂo Santiago, de la Localidad de Ensenada, es visitada mensualmente por integrantes del Observatorio de Riesgo Sanitario. En el lugar circulan parasitosis endĂ©micas como Dioctophyma renale (Dr) y otras que podrĂan caratularse como raras. Tal es el caso del GĂ©nero Capillaria, representado en el lugar, por las especies C. aerophila, bohemi y C. plica en caninos.
Objetivo Describir una jornada educativo sanitaria en el área de estudio de EnsenadaFacultad de Ciencias Veterinaria
Exploring the WEP with a pulsed cold beam of antihydrogen
The AEGIS experiment, currently being set up at the Antiproton Decelerator at CERN, has the objective of studying the free fall of antimatter in the Earth's gravitational field by means of a pulsed cold atomic beam of antihydrogen atoms. Both duration of free fall and vertical displacement of the horizontally emitted atoms will be measured, allowing a first test of the WEP with antimatter
Effect of a quality improvement program on compliance to the sepsis bundle in non-ICU patients: a multicenter prospective before and after cohort study
ObjectiveSepsis and septic shock are major challenges and economic burdens to healthcare, impacting millions of people globally and representing significant causes of mortality. Recently, a large number of quality improvement programs focused on sepsis resuscitation bundles have been instituted worldwide. These educational initiatives have been shown to be associated with improvements in clinical outcomes. We aimed to evaluate the impact of a multi-faceted quality implementing program (QIP) on the compliance of a “simplified 1-h bundle” (Sepsis 6) and hospital mortality of severe sepsis and septic shock patients out of the intensive care unit (ICU).MethodsEmergency departments (EDs) and medical wards (MWs) of 12 academic and non-academic hospitals in the Lombardy region (Northern Italy) were involved in a multi-faceted QIP, which included educational and organizational interventions. Patients with a clinical diagnosis of severe sepsis or septic shock according to the Sepsis-2 criteria were enrolled in two different periods: from May 2011 to November 2011 (before-QIP cohort) and from August 2012 to June 2013 (after-QIP cohort).Measurements and main resultsThe effect of QIP on bundle compliance and hospital mortality was evaluated in a before–after analysis. We enrolled 467 patients in the before-QIP group and 656 in the after-QIP group. At the time of enrollment, septic shock was diagnosed in 50% of patients, similarly between the two periods. In the after-QIP group, we observed increased compliance to the “simplified rapid (1 h) intervention bundle” (the Sepsis 6 bundle – S6) at three time-points evaluated (1 h, 13.7 to 18.7%, p = 0.018, 3 h, 37.1 to 48.0%, p = 0.013, overall study period, 46.2 to 57.9%, p < 0.001). We then analyzed compliance with S6 and hospital mortality in the before- and after-QIP periods, stratifying the two patients’ cohorts by admission characteristics. Adherence to the S6 bundle was increased in patients with severe sepsis in the absence of shock, in patients with serum lactate <4.0 mmol/L, and in patients with hypotension at the time of enrollment, regardless of the type of admission (from EDs or MWs). Subsequently, in an observational analysis, we also investigated the relation between bundle compliance and hospital mortality by logistic regression. In the after-QIP cohort, we observed a lower in-hospital mortality than that observed in the before-QIP cohort. This finding was reported in subgroups where a higher adherence to the S6 bundle in the after-QIP period was found. After adjustment for confounders, the QIP appeared to be independently associated with a significant improvement in hospital mortality. Among the single S6 procedures applied within the first hour of sepsis diagnosis, compliance with blood culture and antibiotic therapy appeared significantly associated with reduced in-hospital mortality.ConclusionA multi-faceted QIP aimed at promoting an early simplified bundle of care for the management of septic patients out of the ICU was associated with improved compliance with sepsis bundles and lower in-hospital mortality
Plant–environment interactions through a functional traits perspective: a review of Italian studies
Italy is among the European countries with the greatest plant diversity due to both a great environmental heterogeneity and a long history of man–environment interactions. Trait-based approaches to ecological studies have developed greatly over recent decades worldwide, although several issues concerning the relationships between plant functional traits and the environment still lack sufficient empirical evaluation. To draw insights on the association between plant functional traits and direct and indirect human and natural pressures on the environmental drivers, this article summarizes the existing knowledge on this topic by reviewing the results of studies performed in Italy adopting a functional trait approach on vascular plants, bryophytes and lichens. Although we recorded trait measurements for 1418 taxa, our review highlighted some major gaps in plant traits knowledge: Mediterranean ecosystems are poorly represented; traits related to belowground organs are still overlooked; traits measurements for bryophytes and lichens are lacking. Finally, intraspecific variation has been little studied at community level so far. We conclude by highlighting the need for approaches evaluating trait–environment relationship at large spatial and temporal scales and the need of a more effective contribution to online databases to tie more firmly Italian researchers to international scientific networks on plant traits