High altitude test of RPCs for the Argo YBJ experiment Bacci, C.; Bao, K.Z.; Barone, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2000, Volume:
443, Issue:
2
Journal Article
Peer reviewed
A 50 m
2 RPC carpet was operated at the YanBaJin Cosmic Ray Laboratory (Tibet) located 4300 m a.s.l. The performance of RPCs in detecting Extensive Air Showers was studied. Efficiency and ...time-resolution measurements at the pressure and temperature conditions typical of high mountain laboratories, are reported.
The excretion of purine derivatives (PD) as an index of microbial biomass production in the rumen can be biased by the endogenous fraction and the incomplete urinary recovery of absorbed purines. ...Moreover, several authors have suggested differences for endogenous fraction of purine derivatives between genetic groups. The objective of this study was to estimate the endogenous fraction of PD and the urinary recovery of purines in Nellore and Holstein heifers fed diets containing 60% corn silage and 40% concentrate daily (13g dry matter/kg body weight). Daily creatinine excretion, intake and digestibility of dry matter and nutrients were also evaluated. Four Nellore heifers and four Holstein heifers fistulated at the rumen and abomasum, body weight of 270±7.76 and 225±7.16kg, respectively, were allocated in two 4×4 Latin squares. The experimental treatments consisted of four doses of RNA infusion (Torula Yeast): 0, 33, 66, or 100mmol/day. The endogenous losses of PD and the recovery of purine bases were estimated using a regression of the daily excretion of PD (Ŷ) and the abomasal flow of purine bases (X). There was no difference (P>0.05) between the regression equations for PD excretion and daily abomasal flow of purines for each genetic group, resulting in the following regression: Ŷ=0.405+0.923X, where 0.405mmol/kg0.75 and 0.923 represent the endogenous fraction and the recovery of purine bases in the abomasum, respectively, for both genetic groups. The infusion and genetic groups did not affect (P>0.05) the daily creatinine excretion, which averaged 27.23mg/kg BW. We concluded that there are no differences between Nellore and Holstein heifers in the endogenous fraction of PD, the urinary recovery of purines, and creatinine excretion, with average values of 0.405mmol/kg0.75, 0.92, and 27.23mg/kg BW, respectively.
An RPC carpet covering
∼10
4
m
2
(ARGO-YBJ experiment) will be installed in the YangBaJing Laboratory (Tibet, People's Republic of China) at an altitude of 4300 m a.s.l. A test-module of
∼50
m
2
has ...been put in operation in this laboratory and about 10
6 air shower events have been collected. The RPC performance at high altitude and the carpet capability of reconstructing the shower features are presented.
Artificial metalloenzymes (ArMs), which combine an abiotic metal cofactor with a protein scaffold, catalyze various synthetically useful transformations. To complement the natural enzymes’ ...repertoire, effective optimization protocols to improve ArM’s performance are required. Here we report on our efforts to optimize the activity of an artificial transfer hydrogenase (ATHase) using Escherichia coli whole cells. For this purpose, we rely on a self-immolative quinolinium substrate which, upon reduction, releases fluorescent umbelliferone, thus allowing efficient screening. Introduction of a loop in the immediate proximity of the Ir-cofactor afforded an ArM with up to 5-fold increase in transfer hydrogenation activity compared to the wild-type ATHase using purified mutants.
The Survival of Motor Neurons (SMN) protein, the product of the spinal muscular atrophy-determining gene, is part of a large macromolecular complex (SMN complex) that functions in the assembly of ...spliceosomal small nuclear ribonucleoproteins (snRNPs). Using cell extracts and purified components, we demonstrated that the SMN complex is necessary and sufficient to mediate the ATP-dependent assembly of the core of seven Sm proteins on uridine-rich, small nuclear ribonucleic acids (U snRNAs). In vitro experiments revealed strict requirements for ordered binding of the Sm proteins and the U snRNAs to the SMN complex. Importantly, the SMN complex is necessary to ensure that Sm cores assemble only on correct RNA targets and prevent their otherwise promiscuous association with other RNAs. Thus, the SMN complex functions as a specificity factor essential for the efficient assembly of Sm proteins on U snRNAs and likely protects cells from illicit, and potentially deleterious, nonspecific binding of Sm proteins to RNAs.
On 2016 July 31 the ICECUBE collaboration reported the detection of a high-energy starting event induced by an astrophysical neutrino. Here, we report on a search for a gamma-ray counterpart to the ...ICECUBE-160731 event, made with the AGILE satellite. No detection was found spanning the time interval of 1 ks around the neutrino event time T0 using the AGILE "burst search" system. Looking for a possible gamma-ray precursor in the results of the AGILE-GRID automatic Quick Look procedure over predefined 48-hr time bins, we found an excess above 100 MeV between 1 and 2 days before T0, which is positionally consistent with the ICECUBE error circle, that has a post-trial significance of about . A refined data analysis of this excess confirms, a posteriori, the automatic detection. The new AGILE transient source, named AGL J1418+0008, thus stands as a possible ICECUBE-160731 gamma-ray precursor. No other space missions nor ground observatories have reported any detection of transient emission consistent with the ICECUBE event. We show that Fermi-LAT had a low exposure for the ICECUBE region during the AGILE gamma-ray transient. Based on an extensive search for cataloged sources within the error regions of ICECUBE-160731 and AGL J1418+0008, we find a possible common counterpart showing some of the key features associated with the high-energy peaked BL Lac (HBL) class of blazars. Further investigations on the nature of this source using dedicated SWIFT ToO data are presented.
We present new observations of the galaxy cluster 3C 129 obtained with the Sardinia Radio Telescope in the frequency range 6000–7200 MHz, with the aim to image the large-angular-scale emission at ...high-frequency of the radio sources located in this cluster of galaxies. The data were acquired using the recently commissioned ROACH2-based backend to produce full-Stokes image cubes of an area of 1°×1° centred on the radio source 3C 129. We modelled and deconvolved the telescope beam pattern from the data. We also measured the instrumental polarization beam patterns to correct the polarization images for off-axis instrumental polarization. Total intensity images at an angular resolution of 2.9 arcmin were obtained for the tailed radio galaxy 3C 129 and for 13 more sources in the field, including 3C 129.1 at the galaxy cluster centre. These data were used, in combination with literature data at lower frequencies, to derive the variation of the synchrotron spectrum of 3C 129 along the tail of the radio source. If the magnetic field is at the equipartition value, we showed that the lifetimes of radiating electrons result in a radiative age for 3C 129 of t
syn ≃ 267 ± 26 Myr. Assuming a linear projected length of 488 kpc for the tail, we deduced that 3C 129 is moving supersonically with a Mach number of M = v
gal/c
s = 1.47. Linearly polarized emission was clearly detected for both 3C 129 and 3C 129.1. The linear polarization measured for 3C 129 reaches levels as high as 70 per cent in the faintest region of the source where the magnetic field is aligned with the direction of the tail.
Context. XSS J1227.0-4859 is a peculiar, hard X-ray source recently positionally associated to the Fermi-LAT source 1FGL J1227.9-4852/2FGL J1227.7-4853. Multi-wavelength observations have added ...information on this source, indicating a low-luminosity low-mass X-ray binary (LMXB), but its nature is still unclear. Aims. To progress in our understanding, we present new X-ray data from a monitoring campaign performed in 2011 with the XMM-Newton, RXTE, and Swift satellites and combine them with new gamma-ray data from the Fermi and AGILE satellites. We complement the study with simultaneous near-UV photometry from XMM-Newton and with previous UV/optical and near-IR data. Methods. We analysed the temporal characteristics in the X-rays, near-UV, and gamma rays and studied the broad-band spectral energy distribution from radio to gamma rays. Results. The X-ray history of XSS J1227 over 7 yr shows a persistent and rather stable low-luminosity (6 × 1033 d1 kpc2 erg s-1) source, with flares and dips being peculiar and permanent characteristics. The associated Fermi-LAT source 2FGL J1227.7-4853 is also stable over an overlapping period of 4.7 yr. Searches for X-ray fast pulsations down to msec give upper limits to pulse fractional amplitudes of 15−25% that do not rule out a fast spinning pulsar. The combined UV/optical/near-IR spectrum reveals a hot component at ~13 kK and a cool one at ~4.6 kK. The latter would suggest a late-type K2−K5 companion star, a distance range of 1.4−3.6 kpc, and an orbital period of 7–9 h. A near-UV variability (≳6 h) also suggests a longer orbital period than previously estimated. Conclusions. The analysis shows that the X-ray and UV/optical/near-IR emissions are more compatible with an accretion-powered compact object than with a rotational powered pulsar. The X-ray to UV bolometric luminosity ratio could be consistent with a binary hosting a neutron star, but the uncertainties in the radio data may also allow an LMXB black hole with a compact jet. In this case, it would be the first associated with a high-energy gamma-ray source.
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