39 research outputs found
The dusty environment of Quasars. Far-IR properties of Optical Quasars
We present the ISO far-IR photometry of a complete sub-sample of optically
selected bright quasars belonging to two complete surveys selected through
multicolour (U,B,V,R,I) techniques. The ISOPHOT camera on board of the ISO
Satellite was used to target these quasars at wavelengths of 7.3, 11.5, 60, 100
and 160 micron. Almost two thirds of the objects were detected at least in one
ISOPHOT band. The detection rate is independent of the source redshift, very
likely due to the negative K-correction of the far-IR thermal emission. More
than a half of the optically selected QSOs show significant emission between 4
and 100 micron in the quasar rest-frame. These fluxes have a very likely
thermal origin, although in a few objects an additional contribution from a
non-thermal component is plausible in the long wavelength bands. In a
colour-colour diagram these objects span a wide range of properties from
AGN-dominated to ULIRG-like. The far-IR composite spectrum of the quasar
population presents a broad far-IR bump between 10 and 30 micron and a sharp
drop at wavelengths greater than 100 micron in the quasar restframe. The amount
of energy emitted in the far-IR, is on average a few times larger than that
emitted in the blue and the ratio L(FIR)/L(B) increases with the bolometric
luminosity. Objects with fainter blue magnitudes have larger ratios between the
far-IR (wavelengths > 60 micron) fluxes and the blue band flux, which is
attributed to extinction by dust around the central source. No relation between
the blue absolute magnitude and the dust colour temperature is seen, suggesting
that the dominant source of FIR energy could be linked to a concurrent
starburst rather than to gravitational energy produced by the central engine.Comment: Astronomical Journal, in pres
Quasar clustering: evidence for an increase with redshift and implications for the nature of AGNs
The evolution of quasar clustering is investigated with a new sample of 388
quasars with 0.3<z<=2.2, B<=20.5 and Mb<-23, selected over an area of 24.6 sq.
deg. in the South Galactic Pole. Assuming a two-point correlation function of
the form xi(r) = (r/r_o)^-1.8, we detect clustering with r_0=6.2 +/- 1.6 h^-1
comoving Mpc at an average redshift of z=1.3. We find a 2 sigma significant
increase of the quasar clustering between z=0.95 and z=1.8, independent of the
quasar absolute magnitude and inconsistent with recent evidence on the
evolution of galaxy clustering. If other quasar samples are added (resulting in
a total data-set of 737 quasars) the increase of the quasar clustering is still
favoured although it becomes less significant. We find epsilon=-2.5.
Evolutionary parameters epsilon>0.0 are excluded at a 0.3% probability level,
to be compared with epsilon=0.8 found for galaxies. The observed clustering
properties appear qualitatively consistent with a scenario of Omega=1 CDM in
which a) the difference between the quasar and the galaxy clustering can be
explained as a difference in the effective bias and redshift distributions, and
b) the quasars, with a lifetime of t~10^8 yr, sparsely sample halos of mass
greater than M_min~10^12-10^13 h^-1 M_sun. We discuss also the possibility that
the observed change in the quasar clustering is due to an increase in the
fraction of early-type galaxies as quasar hosts at high z.Comment: 8 pages including 2 eps figures, LaTeX (AAS v4.0), ApJ in pres
The Asiago-ESO/RASS QSO Survey. III. Clustering analysis and its theoretical interpretation
This is the third paper of a series describing the Asiago-ESO/RASS QSO survey
(AERQS), a project aimed at the construction of an all-sky statistically
well-defined sample of relatively bright QSOs (B<15) at z<0.3. We present here
the clustering analysis of the full spectroscopically identified database (392
AGN). The clustering signal at 0.02<z<0.22 is detected at a 3-4 sigma level and
its amplitude is measured to be r_0=8.6\pm 2.0 h^{-1} Mpc (in a LambdaCDM
model). The comparison with other classes of objects shows that low-redshift
QSOs are clustered in a similar way to Radio Galaxies, EROs and early-type
galaxies in general, although with a marginally smaller amplitude. The
comparison with recent results from the 2QZ shows that the correlation function
of QSOs is constant in redshift or marginally increasing toward low redshift.
We discuss this behavior with physically motivated models, deriving interesting
constraints on the typical mass of the dark matter halos hosting QSOs, M_DMH=
10^{12.7} h^{-1} M_sun (10^{12.0}-10^{13.5}h^{-1} M_sun at 1 sigma confidence
level). Finally, we use the clustering data to infer the physical properties of
local AGN, obtaining M_BH=2 10^8 h^{-1} M_sun (10^7-3 10^9 h^{-1} M_sun) for
the mass of the active black holes, tau_{AGN}= 8 10^6 yr (2 10^{6}-5 10^{7} yr)
for their life-time and eta = 0.14 for their efficiency (always for a LambdaCDM
model).Comment: 37 pages, Astronomical Journal in press. Changes to match the referee
comment
Transformation and tumorigenicity testing of simian cell lines and evaluation of poliovirus replication
The key role of cell cultures in different scientific fields is worldwide recognized, both as in vitro research models alternative to laboratory animals and substrates for biological production. However, many safety concerns rise from the use of animal/human cell lines that may be tumorigenic, leading to potential adverse contaminations in cell-derived biologicals. In order to evaluate the suitability of 13 different cell lines for Poliovirus vaccine production, safety and quality, in vitro/in vivo tumorigenicity and Poliovirus propagation properties were evaluated.
Our results revealed that non-human primate cell lines CYNOM-K1, FRhK-4, 4MBr-5 and 4647 are free of tumorigenic features and represent highly susceptible substrates for attenuated Sabin Poliovirus strains. In particular, FRhK-4 and 4647 cell lines are characterized by a higher in vitro replication, resulting indicated for the use in large-scale production field
On Star Formation Rates and Star Formation Histories of Galaxies out to z ~ 3
We compare multi-wavelength SFR indicators out to z~3 in GOODS-South. Our
analysis uniquely combines U-to-8um photometry from FIREWORKS, MIPS 24um and
PACS 70, 100, and 160um photometry from the PEP survey, and Ha spectroscopy
from the SINS survey. We describe a set of conversions that lead to a
continuity across SFR indicators. A luminosity-independent conversion from 24um
to total infrared luminosity yields estimates of LIR that are in the median
consistent with the LIR derived from PACS photometry, albeit with significant
scatter. Dust correction methods perform well at low to intermediate levels of
star formation. They fail to recover the total amount of star formation in
systems with large SFR_IR/SFR_UV ratios, typically occuring at the highest SFRs
(SFR_UV+IR \gtrsim 100 Msun/yr) and redshifts (z \gtrsim 2.5) probed. Finally,
we confirm that Ha-based SFRs at 1.5<z<2.6 are consistent with SFR_SED and
SFR_UV+IR provided extra attenuation towards HII regions is taken into account
(Av,neb = Av,continuum / 0.44). With the cross-calibrated SFR indicators in
hand, we perform a consistency check on the star formation histories inferred
from SED modeling. We compare the observed SFR-M relations and mass functions
at a range of redshifts to equivalents that are computed by evolving lower
redshift galaxies backwards in time. We find evidence for underestimated
stellar ages when no stringent constraints on formation epoch are applied. We
demonstrate how resolved SED modeling, or alternatively deep UV data, may help
to overcome this bias. The age bias is most severe for galaxies with young
stellar populations, and reduces towards older systems. Finally, our analysis
suggests that SFHs typically vary on timescales that are long (at least several
100 Myr) compared to the galaxies' dynamical time.Comment: Accepted for publication in The Astrophysical Journal, 19 pages, 15
figure
"Delirium Day": A nationwide point prevalence study of delirium in older hospitalized patients using an easy standardized diagnostic tool
Background: To date, delirium prevalence in adult acute hospital populations has been estimated generally from pooled findings of single-center studies and/or among specific patient populations. Furthermore, the number of participants in these studies has not exceeded a few hundred. To overcome these limitations, we have determined, in a multicenter study, the prevalence of delirium over a single day among a large population of patients admitted to acute and rehabilitation hospital wards in Italy. Methods: This is a point prevalence study (called "Delirium Day") including 1867 older patients (aged 65 years or more) across 108 acute and 12 rehabilitation wards in Italian hospitals. Delirium was assessed on the same day in all patients using the 4AT, a validated and briefly administered tool which does not require training. We also collected data regarding motoric subtypes of delirium, functional and nutritional status, dementia, comorbidity, medications, feeding tubes, peripheral venous and urinary catheters, and physical restraints. Results: The mean sample age was 82.0 \ub1 7.5 years (58 % female). Overall, 429 patients (22.9 %) had delirium. Hypoactive was the commonest subtype (132/344 patients, 38.5 %), followed by mixed, hyperactive, and nonmotoric delirium. The prevalence was highest in Neurology (28.5 %) and Geriatrics (24.7 %), lowest in Rehabilitation (14.0 %), and intermediate in Orthopedic (20.6 %) and Internal Medicine wards (21.4 %). In a multivariable logistic regression, age (odds ratio [OR] 1.03, 95 % confidence interval [CI] 1.01-1.05), Activities of Daily Living dependence (OR 1.19, 95 % CI 1.12-1.27), dementia (OR 3.25, 95 % CI 2.41-4.38), malnutrition (OR 2.01, 95 % CI 1.29-3.14), and use of antipsychotics (OR 2.03, 95 % CI 1.45-2.82), feeding tubes (OR 2.51, 95 % CI 1.11-5.66), peripheral venous catheters (OR 1.41, 95 % CI 1.06-1.87), urinary catheters (OR 1.73, 95 % CI 1.30-2.29), and physical restraints (OR 1.84, 95 % CI 1.40-2.40) were associated with delirium. Admission to Neurology wards was also associated with delirium (OR 2.00, 95 % CI 1.29-3.14), while admission to other settings was not. Conclusions: Delirium occurred in more than one out of five patients in acute and rehabilitation hospital wards. Prevalence was highest in Neurology and lowest in Rehabilitation divisions. The "Delirium Day" project might become a useful method to assess delirium across hospital settings and a benchmarking platform for future surveys
Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study
Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research
Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries
Abstract
Background
Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres.
Methods
This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries.
Results
In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia.
Conclusion
This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries