We report on the search for dark matter weakly interacting massive particles (WIMPs) in the mass range below 10 GeV=c2 from the analysis of the entire dataset acquired with a low-radioactivity argon ...target by the DarkSide-50 experiment at Laboratori Nazionali del Gran Sasso. The new analysis benefits from more accurate calibration of the detector response, improved background model, and better determination of systematic uncertainties, allowing us to accurately model the background rate and spectra down to 0.06 keVer. A 90% C.L. exclusion limit for the spin-independent cross section of 3 GeV=c2 mass WIMP on nucleons is set at 6 × 10-43 cm2, about a factor 10 better than the previous DarkSide-50 limit. This analysis extends the exclusion region for spin-independent dark matter interactions below the current experimental constraints in the 1.2, 3.6 GeV=c2 WIMP mass range.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
Aim
Early endoscopic recurrence is frequently observed in patients following resection for Crohn's disease (CD). However, factors affecting the incidence of an early postoperative endoscopic ...recurrence (EPER) have not been fully determined. The aim of this study was to evaluate risk factors for EPER after ileocolonic resection for CD.
Method
This was a retrospective, international multicentre study, in which 127 patients with a first ileocolonoscopy conducted between 6 and 12 months after ileocolonic resection for CD were included. Endoscopic recurrence was defined as a Rutgeerts score of ≥ i2. The following variables were investigated as potential risk factors for EPER: gender, age at surgery, location and behaviour of CD, smoking, concomitant perianal lesions, preoperative use of steroids, immunomodulators and biologics, previous resection, blood transfusion, surgical procedure (open vs laparoscopic approach), length of resected bowel, type of anastomosis (side‐to‐side vs end‐to‐end), postoperative complications, granuloma and postoperative biological therapy. Variables related to the patient, disease and surgical procedure were investigated as potential risk factors for EPER, with univariate and multivariate (logistic regression) analyses.
Results
43/127 (34%) patients had EPER at the time of the first postoperative ileocolonoscopy. In univariate analysis, only preoperative steroid use was significantly associated with a higher rate of EPER 21/45 patients (47%) on steroids and 22/82 patients (27%) without steroids (P = 0.04). In multivariate analysis, only preoperative steroid use was a significant independent risk factor for EPER (odds ratio 3.28, 95% confidence interval: 1.30–8.28; P = 0.01).
Conclusions
This study found that only preoperative steroid use was a significant risk factor for EPER after ileocolonic resection for CD. Prospective studies are necessary to evaluate precisely the impact of perioperative medications on EPER rates.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Finding unequivocal evidence of dark matter interactions in a particle detector is a major goal of research in physics. Liquid argon time projection chambers offer a path to probe Weakly Interacting ...Massive Particles scattering cross sections on nuclei down to the so-called neutrino floor, in a mass range from a few GeV to hundreds of TeV. Based on the successful operation of the DarkSide-50 detector at LNGS, a new and more sensitive experiment, DarkSide-20k, has been designed and is now under construction. A thorough understanding of the DarkSide-50 detector response and, therefore, of all types of events observed in the detector, is essential for the optimal design of the new experiment. In this article, we report on a specific set of events, namely, standard two-pulse scintillation–ionization signals with a third small amplitude pulse, occurring within the 440μs data acquisition window of standard events. Some of these events are due to the photoionization of the TPC cathode. We compare our results with those published by collaborations using liquid xenon time projection chambers, which observed a similar phenomenon, and, in particular, with a recent paper by the LUX Collaboration (D.S. Akerib et al. Phys.Rev.D 102, 092004 (2020)) From the measured rate of these events, we estimate for the first time the quantum efficiency of the tetraphenyl butadiene deposited on the DarkSide-50 cathode at wavelengths of around 128 nm, in liquid argon. Also, both experiments observe events likely related to the photoionization of impurities in the liquid. The probability of photoelectron emission per unit length turns out to be an order of magnitude lower in DarkSide-50 than in LUX.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract Liquid Argon (LAr) Time Projection Chambers (TPC) operating in double-phase can detect the nuclear recoils (NR) possibly caused by the elastic scattering of WIMP dark matter particles via ...light signals from both scintillation and ionization processes. In the scenario of a low-mass WIMP (< 2 GeV/c 2 ), the energy range for the NRs would be below 20 keV, thus making it crucial to characterize the ionization response in LAr TPCs as the lone available detection channel at such low energy. The Recoil Directionality (ReD) project, within the Global Argon Dark Matter Collaboration, aims to measure the ionization yield of a LAr TPC in the recoil energy range of 2–5 keV. The measurement was performed in winter 2023 at the INFN Sezione of Catania and the analysis is ongoing.
Liquid argon is a bright scintillator with potent particle identification properties, making it an attractive target for direct-detection dark matter searches. The DarkSide-50 dark matter search here ...reports the first WIMP search results obtained using a target of low-radioactivity argon. DarkSide-50 is a dark matter detector, using a two-phase liquid argon time projection chamber, located at the Laboratori Nazionali del Gran Sasso. The underground argon is shown to contain super(39) Ar at a level reduced by a factor (1.4+ or -0.2)x10 super(3) relative to atmospheric argon. We report a background-free null result from (2616+ or -43)kgd of data, accumulated over 70.9 live days. When combined with our previous search using an atmospheric argon, the 90% C.L. upper limit on the WIMP-nucleon spin-independent cross section, based on zero events found in the WIMP search regions, is 2.0x10 super(-44)cm super(2)(8.6x10-44cm super(2), 8.0x10 super(-43)cm super(2)) for a WIMP mass of 100GeV/c super(2)(1TeV/c super(2), 10TeV/c super(2)).
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
It is known that electrolytic processes involving the production of gas may have a low yield energetic due to the influence of the bubbles formed on specific electrode geometry. These bubbles ...adhering the electrode surface increases its area of coverage may affect the average mass transfer coefficient and hence the cell potential and the yield process. In the present work, the combined average mass transfer coefficient was determined for the hydrogen production from the electroreduction of K
3Fe(CN)
6 in alkaline solution under diffusional control. Like a reactor to produce electrolytic chlorine-soda, the electrolytic cell was formed by anodic and cathode compartments separated by an asbestos diaphragm. The effects of electrolyte percolation velocity and cathode geometry (perforated plate and metal mesh) were studied. The results showed that for the mesh geometry, the combined average mass transfer coefficient
k
d
*
¯
increased with the average electrolyte percolation velocity through the diaphragm. A contradictory trend was observed for the perforated plate. For average percolation velocities below 3.5
×
10
−5
m
s
−1, the perforated plate showed higher values of
k
d
*
¯
than the mesh geometry. The constants
a and
b of the well-known dimensionless equation
Sh
=
aRe
b
Sc
1/3 were presented for the cases studied.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Fucan is a term used to denote a family of sulfated L-fucose-rich polysaccharides which are present in the extracellular matrix of brown seaweed and in the egg jelly coat of sea urchins. Plant fucans ...have several biological activities, including anticoagulant and antithrombotic, related to the structural and chemical composition of polysaccharides. We have extracted sulfated polysaccharides from the brown seaweed Dictyota menstrualis by proteolytic digestion, followed by separation into 5 fractions by sequential acetone precipitation. Gel electrophoresis using 0.05 M 1,3-diaminopropane-acetate buffer, pH 9.0, stained with 0.1% toluidine blue, showed the presence of sulfated polysaccharides in all fractions. The chemical analyses demonstrated that all fractions are composed mainly of fucose, xylose, galactose, uronic acid, and sulfate. The anticoagulant activity of these heterofucans was determined by activated partial thromboplastin time (APTT) using citrate normal human plasma. Only the fucans F1.0v and F1.5v showed anticoagulant activity. To prolong the coagulation time to double the baseline value in the APTT, the required concentration of fucan F1.0v (20 g/ml) was only 4.88-fold higher than that of the low molecular weight heparin Clexane (4.1 g/ml), whereas 80 g/ml fucan 1.5 was needed to obtain the same effect. For both fucans this effect was abolished by desulfation. These polymers are composed of fucose, xylose, uronic acid, galactose, and sulfate at molar ratios of 1.0:0.8:0.7:0.8:0.4 and 1.0:0.3:0.4:1.5:1.3, respectively. This is the fist report indicating the presence of a heterofucan with higher anticoagulant activity from brown seaweed.
Purpose
Excess weight may be related to the development of adverse cardiometabolic risk factors in children. The aim of this study was to evaluate the effect of a lifestyle intervention program ...(nutrition and exercise counseling) on anthropometric parameters and metabolic syndrome (MS) components in Portuguese overweight/obese children.
Methods
A total of 83 overweight/obese children aged 7–9 years were assigned to a 1-year individual or group-based treatment (GT); 61 children (z-score BMI (zBMI): 1.93 ± 0.28; 27 boys and 34 girls) completed the program. Anthropometric and biochemical parameters were assessed at baseline, at 6 months and at 1 year.
Results
The overweight/obese children, compared to normal-weight ones, presented significantly higher blood pressure, total-cholesterol, total-cholesterol/high density lipoprotein cholesterol (HDL) ratio, triglycerides, Apolipoprotein B and C-reactive protein levels, while HDL and Apolipoprotein A-I were significantly lower. At baseline, the prevalence of MS was 16.4% in overweight/obese and 0% in normal-weight children. The number of components of MS was significantly higher in children with higher zBMI. Lifestyle intervention led to a significant improvement in zBMI, waist circumference/height ratio, HDL, triglycerides, Apolipoprotein A-I, and Apolipoprotein B levels. The prevalence of MS decreased to 14.8%. The GT intervention seems to be more successful, with a significant decrease in zBMI and an increase in HDL and a lower drop-out rate.
Conclusions
Overweight/obese children have multiple risk factors associated with the MS. Lifestyle intervention, both individual and group-based treatment, led to an improvement in the degree of overweight/obesity and in MS components.
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DOBA, EMUNI, FIS, FSPLJ, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, VSZLJ, ZAGLJ
DarkSide-50 is a detector for dark matter candidates in the form of weakly interacting massive particles. It utilizes a liquid argon time projection chamber for the inner main detector, surrounded by ...a liquid scintillator veto (LSV) and a water Cherenkov veto detector (WCV). The LSV and WCV act as the neutron and cosmogenic muon veto detectors for DarkSide-50. This paper describes the electronics and data acquisition system used for these two detectors. The system is made of a custom built front end electronics and commercial National Instruments high speed digitizers. The front end electronics, the DAQ, and the trigger system have been used to acquire data in the form of zero-suppressed waveform samples from the 110 PMTs of the LSV and the 80 PMTs of the WCV. The veto DAQ system has proven its performance and reliability. This electronics and DAQ system can be scaled and used as it is for the veto of the next generation DarkSide-20k detector
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