Abstract
Supplying power at low voltage to the front-end electronics
of very fast and highly segmented detectors, typical in the
experiments at the Large Hadron Collider, involves several issues,
...including transient currents and voltages. This study investigates
a power chain that involves long cables, DC-DC converters, and input
filters. Due to the presence of a common ground close to the input
of the DC-DC converter, the power chain can run with a lower value
of the input supply. It is seen that the capacitor in the input
filter plays a significant role in the process of voltage growth at
the input of the DC-DC converter. The effects of the ramp during
turning ON and OFF the input supply have been studied thoroughly.
It is observed that the voltage/current spikes are reduced due to
the application of the ramp. It is also observed that the
current/voltage, both at the input and the output of the DC-DC
converter, goes through some intermediate oscillations due to the
existence of threshold voltage for the converters. The choice of
the ramp is critical in reducing spikes and should be incorporated
into the power supply.
The experiments at the Large Hadron Collider are upgrading their detectors for the coming High Luminosity run. Powering the on board electronics of the highly segmented tracking detectors is a ...challenge because of the stringent requirements on location, space constraint, fine segmentation, radiation and magnetic field tolerance, thermal loss, etc. Similar issues will be relevant for the future colliding beam experiments, also. This paper reports early studies of the Low Voltage Power Supply for the upgrade of the Outer Tracker detector of the Compact Muon Solenoid experiment. The proposed power chain uses point of load DC-DC converters. The studies, with simulations and experimental measurements, have identified a number of critical issues related to the voltages and currents of the DC-DC converters under different operating conditions. A few constraints on the design of such a system have been identified and in some cases remedial measures to circumvent such constraints have been suggested.
The study was designed to determine the haematological and biochemical alterations in sero-negative native sheep following the experimental bluetongue virus serotype-2 (BTV-2) infection. The BTV ...infected group comprised 14 sheep inoculated with 6 ml of clarified virus containing 1×106/ml TCID50 of BTV-2 by intradermal route. The uninfected control group comprised 6 animals inoculated with 6 ml of cell culture medium without virus by intradermal route. The blood and serum samples were analyzed at 0, 1, 2, 3, 7, 11, 14, 21 and 45 days post-infection (dpi). Significant changes were observed in all the haematological and biochemical parameters studied. Marked leucopenia was observed from 2 to 7 dpi in BTV infected group. Significant leucocytosis was documented during 11 to 14 dpi in infected group. Significant thrombocytopenia was observed during 2 to 14 dpi whereas significantly low packed cell volume (PCV) and haemoglobin (Hb) values were observed between 3 and 21 dpi in BTV infected group. Differential leucocyte count revealed significantly low lymphocyte percentage on day 3 and high on day 11 in infected group. The various biochemical enzymes like alanine aminotransferase (ALT) showed significantlyhigh values during 3 to 21 dpi, aspartate aminotransferase (AST) during 3 to 21 dpi, alkaline phosphatise (ALP) during 3 to 11 dpi and creatine kinase (CK) during 7 to 14 dpi in BTV infected group. The result of our study demonstrated significantly decreased levels of total leucocyte count, total platelet count, haemoglobin and PCV values while significantly increased levels of ALT, AST, ALP and CK values in BTV infected group. On histopathological examination, spleen and lymph nodes showed depletion of lymphoid cells, liver and kidney showed degeneration, congestion and haemorrhage at many places. The BTV nucleic acid was detected from blood and tissues by RT-PCR. These findings indicated the damage to various soft tissue organs and muscles as a sequel to vascular endothelial damages caused by BTV.
Aim: Rapid emergence of arsenic pollution demands the development of novel adjunct with non-invasive painless oral therapeutic agent to combat against arsenic associated health hazards by replacing ...conventional painful chelating therapy. In the present study, the modulatory effects of vitamin B12 and folic acid (folate) in the amelioration of arsenic mediated uterine disorders were examined. Methodology: In this experimental study, Wistar strain adult female rats were fed sodium arsenite (As3+) contaminated water (0.4 ppm) in conjunction with vitamin B12 (0.04 pg and 0.07 pg) plus folate (2.0 and 4.0 pg) alone and or in combination respectively per 100 g b.wt. per day fors even estrous cycles (28 days). Results: Rats those underwent arsenic exposure showed significant impairments in the status of uterine antioxidant profile as evident from enzymatic assay and electrozymogram study of superoxide dismutase, catalase and peroxidase with an abnormal increase in conjugated diene and malondialdehyde levels. Mutagenic uterine DNA-breakage and tissue damages were prominent following As3+consumption by the rats. All impairments were totally or partially attenuated by the co-treatment with these two B vitamins in arsenic exposed rats. Interpretation: The mechanisms might be coupled with the enhancement of antioxidant defense system, partly through the elimination ofarsenic with the involvement of S-adenosine methionine pool (SAM) since, vitamin B12 and folic acid are two major regulators ofthis pool.
Focus point SUSY at the LHC revisited Das, S.P.; Datta, A.; Guchait, M. ...
The European physical journal. C, Particles and fields,
04/2008, Letnik:
54, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The estimation of the backgrounds for gluino signals in focus point supersymmetry is extended by including the backgrounds from the production of four third generation quarks in the analysis. We find ...that these backgrounds are negligible if one uses the strong selection criteria proposed in the literature (including this analysis) for heavy gluino searches. Softer selection criteria often recommended for lighter gluino searches yield backgrounds that are small but numerically significant. We have also repeated the more conventional background calculations and compared our results with the other groups. We find that the size of the total residual background estimated by different groups using different event generators and hard kinematical cuts agree approximately. In view of the theoretical uncertainties in the leading order signal and background cross sections mainly due to the choice of the QCD scale, the gluino mass reach at the LHC cannot be pinpointed. However, requiring a signal with ≥3 tagged b-jets (instead of the standard choice of ≥2) it is shown that gluino masses close to 2 TeV can be probed at the LHC for a range of reasonable choices of the QCD scale for an integrated luminosity of 300 fb
-1
.
In July 2012, the ATLAS and CMS collaborations at the CERN Large Hadron Collider announced the observation of a Higgs boson at a mass of around 125 gigaelectronvolts. Ten years later, and with the ...data corresponding to the production of a 30-times larger number of Higgs bosons, we have learnt much more about the properties of the Higgs boson. The CMS experiment has observed the Higgs boson in numerous fermionic and bosonic decay channels, established its spin-parity quantum numbers, determined its mass and measured its production cross-sections in various modes. Here the CMS Collaboration reports the most up-to-date combination of results on the properties of the Higgs boson, including the most stringent limit on the cross-section for the production of a pair of Higgs bosons, on the basis of data from proton-proton collisions at a centre-of-mass energy of 13 teraelectronvolts. Within the uncertainties, all these observations are compatible with the predictions of the standard model of elementary particle physics. Much evidence points to the fact that the standard model is a low-energy approximation of a more comprehensive theory. Several of the standard model issues originate in the sector of Higgs boson physics. An order of magnitude larger number of Higgs bosons, expected to be examined over the next 15 years, will help deepen our understanding of this crucial sector.
Protein Folding: The Stepwise Assembly of Foldon Units Maity, Haripada; Maity, Mita; Mallela M. G. Krishna ...
Proceedings of the National Academy of Sciences - PNAS,
03/2005, Letnik:
102, Številka:
13
Journal Article
Recenzirano
Odprti dostop
Equilibrium and kinetic hydrogen exchange experiments show that cytochrome c is composed of five foldon units that continually unfold and refold even under native conditions. Folding proceeds by the ...stepwise assembly of the foldon units rather than one amino acid at a time. The folding pathway is determined by a sequential stabilization process; previously formed foldons guide and stabilize subsequent foldons to progressively build the native protein. Four other proteins have been found to show similar behavior. These results support stepwise protein folding pathways through discrete intermediates.
New sets of CMS underlying-event parameters (“tunes”) are presented for the
pythia
8 event generator. These tunes use the NNPDF3.1 parton distribution functions (PDFs) at leading (LO), ...next-to-leading (NLO), or next-to-next-to-leading (NNLO) orders in perturbative quantum chromodynamics, and the strong coupling evolution at LO or NLO. Measurements of charged-particle multiplicity and transverse momentum densities at various hadron collision energies are fit simultaneously to determine the parameters of the tunes. Comparisons of the predictions of the new tunes are provided for observables sensitive to the event shapes at LEP, global underlying event, soft multiparton interactions, and double-parton scattering contributions. In addition, comparisons are made for observables measured in various specific processes, such as multijet, Drell–Yan, and top quark-antiquark pair production including jet substructure observables. The simulation of the underlying event provided by the new tunes is interfaced to a higher-order matrix-element calculation. For the first time, predictions from
pythia
8 obtained with tunes based on NLO or NNLO PDFs are shown to reliably describe minimum-bias and underlying-event data with a similar level of agreement to predictions from tunes using LO PDF sets.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The observation of the standard model (SM) Higgs boson decay to a pair of bottom quarks is presented. The main contribution to this result is from processes in which Higgs bosons are produced in ...association with a W or Z boson (VH), and are searched for in final states including 0, 1, or 2 charged leptons and two identified bottom quark jets. The results from the measurement of these processes in a data sample recorded by the CMS experiment in 2017, comprising 41.3 fb^{-1} of proton-proton collisions at sqrts=13 TeV, are described. When combined with previous VH measurements using data collected at sqrts=7, 8, and 13 TeV, an excess of events is observed at m_{H}=125 GeV with a significance of 4.8 standard deviations, where the expectation for the SM Higgs boson is 4.9. The corresponding measured signal strength is 1.01±0.22. The combination of this result with searches by the CMS experiment for H→bbover ¯ in other production processes yields an observed (expected) significance of 5.6 (5.5) standard deviations and a signal strength of 1.04±0.20.
Evidence for the light-by-light scattering process, γγ→γγ, in ultraperipheral PbPb collisions at a centre-of-mass energy per nucleon pair of 5.02TeV is reported. The analysis is conducted using a ...data sample corresponding to an integrated luminosity of 390μb−1 recorded by the CMS experiment at the LHC. Light-by-light scattering processes are selected in events with two photons exclusively produced, each with transverse energy ETγ>2GeV, pseudorapidity |ηγ|<2.4, diphoton invariant mass mγγ>5GeV, diphoton transverse momentum pTγγ<1GeV, and diphoton acoplanarity below 0.01. After all selection criteria are applied, 14 events are observed, compared to expectations of 9.0±0.9(theo) events for the signal and 4.0±1.2(stat) for the background processes. The excess observed in data relative to the background-only expectation corresponds to a significance of 3.7 standard deviations, and has properties consistent with those expected for the light-by-light scattering signal. The measured fiducial light-by-light scattering cross section, σfid(γγ→γγ)=120±46(stat)±28(syst)±12(theo)nb, is consistent with the standard model prediction. The mγγ distribution is used to set new exclusion limits on the production of pseudoscalar axion-like particles, via the ▪ process, in the mass range ▪.
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