The ATLAS luminosity monitor, LUCID (LUminosity Cherenkov Integrating Detector), had to be upgraded for the second run of the LHC accelerator that started in spring 2015. The increased energy of the ...proton beams and the higher luminosity required a redesign of LUCID to cope with the more demanding conditions. The novelty of the LUCID-2 detector is that it uses the thin quartz windows of photomultipliers as Cherenkov medium and a small amounts of radioactive 207Bi sources deposited on to these windows to monitor the gain stability of the photomultipliers. The result is a fast and accurate luminosity determination that can be kept stable during many months of data taking. LUCID-2 can also measure the luminosity accurately online for each of the up to 2808 colliding bunch pairs in the LHC . These bunch pairs are separated by only 25 ns and new electronics has been built that can count not only the number of pulses above threshold but also integrate the pulses.
Gelatin microparticles containing propolis extractive solution (PES) were prepared by spray-drying technique. The optimization of the spray-drying operating conditions and the proportions of gelatin ...and mannitol were investigated. Regular particle morphology was obtained when mannitol was used, whereas mannitol absence produced a substantial number of coalesced and agglomerated microparticles. Microparticles had a mean diameter of 2.70
μm without mannitol and 2.50
μm with mannitol. The entrapment efficiency for propolis of the microparticles was upto 41% without mannitol and 39% with mannitol. The microencapsulation by spray-drying technique maintained the activity of propolis against
Staphylococcus aureus. These gelatin microparticles containing propolis would be useful for developing intermediary or eventual propolis dosage form without the PES’ strong and unpleasant taste, aromatic odour, and presence of ethanol.
The ATLAS luminosity monitor Bruschi, M.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2010, Letnik:
623, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The main luminosity monitor of the ATLAS experiment consists of an array of Cherenkov counters. The intrinsically fast response of the detector and its readout electronics makes it ideal for ...measuring the number of interactions per LHC bunch crossing, and for providing an interaction trigger to the ATLAS experiment. The detector already took some data during the first beam interactions produced by the LHC. An original method to derive the detector response with an analytical approach is presented here.
The prevalence of obesity has increased to epidemic status worldwide. Thousands of morbidly obese individuals undergo bariatric surgery for sustained weight loss; however, mid- and long-term outcomes ...of this surgery are still uncertain. Our objective was to estimate the 10-year mortality rate, and determine risk factors associated with death in young morbidly obese adults who underwent bariatric surgery. All patients who underwent open Roux-in-Y gastric bypass surgery between 2001 and 2010, covered by an insurance company, were analyzed to determine possible associations between risk factors present at the time of surgery and deaths related and unrelated to the surgery. Among the 4344 patients included in the study, 79% were female with a median age of 34.9 years and median body mass index (BMI) of 42 kg/m(2). The 30-day and 10-year mortality rates were 0.55 and 3.34%, respectively, and 53.7% of deaths were related to early or late complications following bariatric surgery. Among these, 42.7% of the deaths were due to sepsis and 24.3% to cardiovascular complications. Male gender, age ≥50 years, BMI ≥50 kg/m(2), and hypertension significantly increased the hazard for all deaths (P<0.001). Age ≥50 years, BMI ≥50 kg/m(2), and surgeon inexperience elevated the hazard of death from causes related to surgery. Male gender and age ≥50 years were the factors associated with increased mortality from death not related to surgery. The overall risk of death after bariatric surgery was quite low, and half of the deaths were related to the surgery. Older patients and superobese patients were at greater risk of surgery-related deaths, as were patients operated on by less experienced surgeons.
The present and future potential of ATLAS for diffraction and forward physics is presented. As recent results the rapidity gap cross section and elastic and total pp cross sections are reported. The ...upgrade project AFP is presented and it is shown how it will complement the ALFA acceptance for diffractive physics in measurements taken with β*=90 m LHC beam optics. Moreover, the AFP detector will guarantee good acceptance on diffractive events also during normal running conditions allowing to improve the ATLAS detector performances. If in addition, a high luminosity program will be feasible, AFP might be fundamental for potential discoveries with extra dimensions being one example.
Some matrix functional equations Bruschi, M.; Calogero, F.
Theoretical and mathematical physics,
10/2016, Letnik:
189, Številka:
1
Journal Article
Recenzirano
We investigate the pair of matrix functional equations
G
(
x
)
F
(
y
) =
G
(
xy
) and
G
(
x
)
G
(
y
) =
F
(
y
/
x
), featuring the two independent scalar variables x and y and the two
N×N
matrices
F
...(
z
)
and
G
(
z
) (with N an arbitrary positive integer and the elements of these two matrices functions of the scalar variable z). We focus on the simplest class of solutions, i.e., on matrices all of whose elements are analytic functions of the independent variable. While in the scalar (
N
= 1) case this pair of functional equations only possess altogether trivial constant solutions, in the matrix (
N
> 1) case there are nontrivial solutions. These solutions satisfy the additional pair of functional equations
F
(
x
)
G
(
y
) =
G
(
y
/
x
)
and
F
(
x
)
F
(
y
) =
F
(
xy
), and an endless hierarchy of other functional equations featuring more than two independent variables.
Leafcutter ants propagate co‐evolving fungi for food. The nearly 50 species of leafcutter ants (Atta, Acromyrmex) range from Argentina to the United States, with the greatest species diversity in ...southern South America. We elucidate the biogeography of fungi cultivated by leafcutter ants using DNA sequence and microsatellite‐marker analyses of 474 cultivars collected across the leafcutter range. Fungal cultivars belong to two clades (Clade‐A and Clade‐B). The dominant and widespread Clade‐A cultivars form three genotype clusters, with their relative prevalence corresponding to southern South America, northern South America, Central and North America. Admixture between Clade‐A populations supports genetic exchange within a single species, Leucocoprinus gongylophorus. Some leafcutter species that cut grass as fungicultural substrate are specialized to cultivate Clade‐B fungi, whereas leafcutters preferring dicot plants appear specialized on Clade‐A fungi. Cultivar sharing between sympatric leafcutter species occurs frequently such that cultivars of Atta are not distinct from those of Acromyrmex. Leafcutters specialized on Clade‐B fungi occur only in South America. Diversity of Clade‐A fungi is greatest in South America, but minimal in Central and North America. Maximum cultivar diversity in South America is predicted by the Kusnezov–Fowler hypothesis that leafcutter ants originated in subtropical South America and only dicot‐specialized leafcutter ants migrated out of South America, but the cultivar diversity becomes also compatible with a recently proposed hypothesis of a Central American origin by postulating that leafcutter ants acquired novel cultivars many times from other nonleafcutter fungus‐growing ants during their migrations from Central America across South America. We evaluate these biogeographic hypotheses in the light of estimated dates for the origins of leafcutter ants and their cultivars.
Developing new bioremediation processes for soils and effluents polluted by Cr(VI) requires the selection of the most efficient and the most heavy-metal-resistant bacteria. The effects of Cr(VI) on ...bioenergetic metabolism in two sulfate-reducing bacteria (SRB), Desulfovibrio vulgaris Hildenborough and Desulfomicrobium norvegicum, were monitored using isothermal microcalorimetry. The complete reduction of Cr(VI) to Cr(III) was studied by spectrophotometry and by speciation using a combination of high-performance liquid chromatography and inductively coupled plasma-mass spectrometry. Results revealed that Cr(VI) induces an inhibition of growth with concomitant production of energy, which can be compared to the reaction of the bacteria to a stress such as oxidative stress. Moreover, the sensitivity of bacteria towards this metal is as a characteristic of the strain, which leads to differences in the kinetics of Cr(VI) reduction. The study by microcalorimetry of heavy metal effects on SRB bioenergetic metabolism thus appears an appropriate tool to identify better strains to be used for industrial bioremediation process development.
Various sulfate-reducing bacteria of the genera Desulfovibrio and Desulfomicrobium were tested and compared for enzymatic reduction of chromate. Our study demonstrated that the ability to reduce ...chromate is widespread among sulfate-reducing bacteria. Among them, Desulfomicrobium norvegicum reduced Cr(VI) with the highest reaction rate. This strain grew in the presence of up to 500 microM chromate, but Cr(VI) reduction in the absence of sulfate was not associated with growth. The presence of chromate induced morphological changes and leakage of periplasmic proteins into the medium. The ability of isolated polyheme cytochromes c from sulfate- and sulfur-reducing bacteria to reduce chromate was also analyzed. Tetraheme cytochrome c3(Mr. 13,000) from Desulfomicrobium norvegicum showed twice as much activity as either tetraheme cytochrome c3 from Desulfovibrio vulgaris strain Hildenborough or triheme cytochrome c7 from Desulfuromonas acetoxidans. Results with cytochromes c3 and other c-type cytochromes altered by site-directed mutagenesis indicated that negative redox potential hemes are crucial for metal reductase activity. The present study also demonstrated that the (Fe) hydrogenase from sulfate-reducing bacteria could reduce chromate.
The ATLAS Forward Proton (AFP) detector is intended to measure protons scattered at small angles from the ATLAS interaction point. To this end, a combination of 3D Silicon pixel tracking modules and ...Quartz-Cherenkov time-of-flight (ToF) detectors is installed 210 m away from the interaction point at both sides of ATLAS. Beam tests with an AFP prototype detector combining tracking and timing sub-detectors and a common readout have been performed at the CERN-SPS test-beam facility in November 2014 and September 2015 to complete the system integration and to study the detector performance. The successful tracking-timing integration was demonstrated. Good tracker hit efficiencies above 99.9% at a sensor tilt of 14degrees, as foreseen for AFP, were observed. Spatial resolutions in the short pixel direction with 50 mum pitch of 5.5 + or - 0.5 mum per pixel plane and of 2.8 + or - 0.5 mum for the full four-plane tracker at 14degrees were found, largely surpassing the AFP requirement of 10 mum. The timing detector showed also good hit efficiencies above 99%, and a full-system time resolution of 35+ or -6 ps was found for the ToF prototype detector with two Quartz bars in-line (half the final AFP size) without dedicated optimisation, fulfilling the requirements for initial low-luminosity AFP runs.
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