139 research outputs found
The dependence of halo bias on age, concentration and spin
Halo bias is the main link between the matter distribution and dark matter
halos. In its simplest form, halo bias is determined by halo mass, but there
are known additional dependencies on other halo properties which are of
consequence for accurate modeling of galaxy clustering. Here we present the
most precise measurement of these secondary-bias dependencies on halo age,
concentration, and spin, for a wide range of halo masses spanning from
10 to 10 M. At the high-mass end, we find
no strong evidence of assembly bias for masses above M
M. Secondary bias exists, however, for halo concentration
and spin, up to cluster-size halos, in agreement with previous findings. For
halo spin, we report, for the first time, two different regimes: above
M10 M, halos with larger values of spin
have larger bias, at fixed mass, with the effect reaching almost a factor 2.
This trend reverses below this characteristic mass. In addition to these
results, we test, for the first time, the performance of a multi-tracer method
for the determination of the relative bias between different subsets of halos.
We show that this method increases significantly the signal-to-noise of the
secondary-bias measurement as compared to a traditional approach. This analysis
serves as the basis for follow-up applications of our multi-tracer method to
real data.Comment: 11 pages, 6 figures, submitted to MNRA
Xenon Anesthesia Improves Respiratory Gas Exchanges in Morbidly Obese Patients
Background. Xenon-in-oxygen is a high density gas mixture and may improve PaO2/FiO2 ratio in morbidly obese patients uniforming distribution of ventilation during anesthesia. Methods. We compared xenon versus sevoflurane anesthesia in twenty adult morbidly obese patients (BMI > 35) candidate for roux-en-Y laparoscopic gastric bypass and assessed PaO2/FiO2 ratio at baseline, at 15 min from induction of anaesthesia and every 60 min during surgery. Differences in intraoperative and postoperative data including heart rate, systolic and diastolic pressure, oxygen saturation, plateau pressure, eyes opening and extubation time, Aldrete score on arrival to the PACU were compared by the Mann-Whitney test and were considered as secondary aims. Moreover the occurrence of side effects and postoperative analgesic demand were assessed. Results. In xenon group PaO2-FiO2 ratio was significantly higher after 60 min and 120 min from induction of anesthesia; heart rate and overall remifentanil consumption were lower; the eyes opening time and the extubation time were shorter; morphine consumption at 72 hours was lower; postoperative nausea was more common. Conclusions. Xenon anesthesia improved PaO2/FiO2 ratio and maintained its distinctive rapid recovery times and cardiovascular stability. A reduction of opioid consumption during and after surgery and an increased incidence of PONV were also observed in xenon group
Photometric type Ia supernova surveys in narrow band filters
We study the characteristics of a narrow band type Ia supernova survey
through simulations based on the upcoming Javalambre Physics of the
accelerating universe Astrophysical Survey (J-PAS). This unique survey has the
capabilities of obtaining distances, redshifts, and the SN type from a single
experiment thereby circumventing the challenges faced by the resource-intensive
spectroscopic follow-up observations. We analyse the flux measurements
signal-to-noise ratio and bias, the supernova typing performance, the ability
to recover light curve parameters given by the SALT2 model, the photometric
redshift precision from type Ia supernova light curves and the effects of
systematic errors on the data. We show that such a survey is not only feasible
but may yield large type Ia supernova samples (up to 250 supernovae at
per month of search) with low core collapse contamination ( per
cent), good precision on the SALT2 parameters (average ,
and ) and on the distance modulus (average
, assuming an intrinsic scatter
), with identified systematic uncertainties
. Moreover, the
filters are narrow enough to detect most spectral features and obtain excellent
photometric redshift precision of , apart from 2 per
cent of outliers. We also present a few strategies for optimising the survey's
outcome. Together with the detailed host galaxy information, narrow band
surveys can be very valuable for the study of supernova rates, spectral feature
relations, intrinsic colour variations and correlations between supernova and
host galaxy properties, all of which are important information for supernova
cosmological applications.Comment: 20 pages, 12 tables and 26 figures. Version accepted by MNRAS, with
results slightly different from previous on
High-fidelity reproduction of central galaxy joint distributions with Neural Networks
The relationship between galaxies and haloes is central to the description of
galaxy formation, and a fundamental step towards extracting precise
cosmological information from galaxy maps. However, this connection involves
several complex processes that are interconnected. Machine Learning methods are
flexible tools that can learn complex correlations between a large number of
features, but are traditionally designed as deterministic estimators. In this
work, we use the IllustrisTNG300-1 simulation and apply neural networks in a
binning classification scheme to predict probability distributions of central
galaxy properties, namely stellar mass, colour, specific star formation rate,
and radius, using as input features the halo mass, concentration, spin, age,
and the overdensity on a scale of 3 Mpc. The model captures the
intrinsic scatter in the relation between halo and galaxy properties, and can
thus be used to quantify the uncertainties related to the stochasticity of the
galaxy properties with respect to the halo properties. In particular, with our
proposed method, one can define and accurately reproduce the properties of the
different galaxy populations in great detail. We demonstrate the power of this
tool by directly comparing traditional single-point estimators and the
predicted joint probability distributions, and also by computing the power
spectrum of a large number of tracers defined on the basis of the predicted
colour-stellar mass diagram. We show that the neural networks reproduce
clustering statistics of the individual galaxy populations with excellent
precision and accuracy.Comment: 12 pages, 7 figure
Bridging aortic valve surgery to 21st century. what can a surgeon do
Aortic valve stenosis is the most clinically relevant valvular heart disease in the elderlies. Surgical aortic valve replacement (SAVR) represented, for decades, the standard of care for the treatment of severe aortic stenosis. Although SAVR still represents a valid option in this clinical scenario, transcatheter aortic valve implantation proved to be superior to medical therapy and comparable to SAVR in several randomized trials in patients at high or intermediate operative risk. At the same time, the growing aging population carrying on greater morbidities and high risk profiles has led to the development of minimally invasive technologies, as rapid deployment aortic valve replacement or Sutureless, to minimize surgical impact on patients. The Heart Team is nowadays tasked to determine the best option tailored for each patient considering patient-related factors and mastering all the surgical options in terms of both different techniques and types of available valves. Nevertheless, some open issues need to be already answered as: which has the longest durability, which the lower complication rate and the lower overall mortality. The aim of this review is to briefly resume the main features of these different options and explore what kind of open questions these newer-generation prosthetic valves and delivery devices carry
Early identification of acute kidney injury after bariatric surgery: Role of NGAL and cystatin C
Background:
The aim of our study was to evaluate plasmatic and urinary NGAL and serum cystatin C as early diagnostic markers of acute kidney injury in obese patients undergoing bariatric surgery.
Methods:
For this this prospective observational study, we recruited 23 patients undergoing gastric by-pass or sleeve gastrectomy, and admitted to the Low Dependence Unit after the surgery. Plasma NGAL (pNGAL), urinary NGAL (uNGAL), serum cystatin C, serum creatinine, and serum urea were measured before surgery as well as 10 h and 24 h after surgery.
Mean values of pNGAL, uNGAL, cystatin C, creatinine, and urea concentrations of pre- and post-surgery periods were compared using Student’s t test for paired data. We also evaluated the presence of correlation between modifications of NGAL and cystatin C after surgery and fluid balance, hydration (ml/kg) and diuresis using Pearson’s coefficient of correlation.
Results:
No patient developed AKI according to the AKIN criteria. pNGAL was significantly higher at T10th than T0(p=0.004). There was no significant difference between uNGAL at T0 and T10th (p=0.53) and between uNGAL at T0 and T24th (p=0.31). uNGAL at T24th was significantly higher in comparison to T10th (p=0.024). uNGAL concentrations were normal in all patients at every time step.
Cystatin C concentration did not increase after surgery.
Serum creatinine level was significantly higher at T48th, despite being still within the normal range, when compared to T0 (p=0.038).
Conclusion:
Our study shows that pNGAL can reflect mild tubular damage as its levels increase within a few hours from surgery and return to normal limits afterwards. Concerning uNGAL, there is a minimal increase at T24th, when NGAL concentration in plasma has already decreased. Serum cystatin C does not show any relevant kidney changes, or at least, no more than those ones shown by pNGAL
Social Aspects of Diabetic Foot: A Scoping Review
Diabetic foot ulcer (DFU) is a severe complication of diabetes mellitus (DM). Patients with DFU have increased mortality and morbidity as well as decreased quality of life (QoL). The present scoping review aims to study the social issues of diabetic foot. Following PRISMA guidelines, the review was conducted in two databases (Scopus and Pubmed) with the use of the following keywords: “social aspects and diabetic foot”, “social characteristics and diabetic foot”, “social issues and diabetic foot”, “demographic profiles and diabetic foot”, “social determinants and diabetic foot”, “social capital and diabetic foot”, “social characteristics and gender and diabetic foot”, “social profiles and diabetic foot”, “social relationships and diabetic foot” and “social risk and diabetic foot”, from July to August 2021. Predetermined exclusion and inclusion criteria were selected. Forty-five studies (quantitative and qualitative) were eligible for inclusion in this review. Gender problems, socioeconomic status, social capital, and medical problems were the most important negative variables for diabetic foot. All the included variables reveal that the social impact of diabetic foot is the most important factor for management and prevention, in terms of aggravation and more, of the diabetic foo
Effect of 1,3-1,6 β-Glucan on Natural and Experimental Deformed Wing Virus Infection in Newly Emerged Honeybees (Apis mellifera ligustica)
The Western Honeybee is a key pollinator for natural as well as agricultural ecosystems. In the last decade massive honeybee colony losses have been observed worldwide, the result of a complex syndrome triggered by multiple stress factors, with the RNA virus Deformed Wing Virus (DWV) and the mite Varroa destructor playing crucial roles. The mite supports replication of DWV to high titers, which exert an immunosuppressive action and correlate with the onset of the disease. The aim of this study was to investigate the effect of 1,3-1,6 β-glucan, a natural innate immune system modulator, on honeybee response to low-titer natural and high-titer experimental DWV infection. As the effects exerted by ß-glucans can be remarkably different, depending on the target organism and the dose administered, two parallel experiments were performed, where 1,3-1,6 ß-glucan at a concentration of 0.5% and 2% respectively, was added to the diet of three cohorts of newly emerged honeybees, which were sampled from a Varroa-free apiary and harboured a low endogenous DWV viral titer. Each cohort was subjected to one of the following experimental treatments: no injection, injection of a high-copy number DWV suspension into the haemocel (experimental DWV infection) or injection of PBS into the haemocoel (physical injury). Control bees fed a ß-glucan-free diet were subjected to the same treatments. Viral load, survival rate, haemocyte populations and phenoloxidase activity of each experimental group were measured and compared. The results indicated that oral administration of 0.5% ß-glucan to naturally infected honeybees was associated with a significantly decrease of the number of infected bees and viral load they carried, and with a significant increase of the survival rate, suggesting that this natural immune modulator molecule might contribute to increase honeybee resistance to viral infection
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