Hu Go - Academia.edu (original) (raw)
Papers by Hu Go
Journal of High Energy Physics, 2010
Measurements of inclusive charged-hadron transverse-momentum and pseudorapidity distributions are... more Measurements of inclusive charged-hadron transverse-momentum and pseudorapidity distributions are presented for proton-proton collisions at √ s = 0.9 and 2.36 TeV. The data were collected with the CMS detector during the LHC commissioning in December 2009. For non-single-diffractive interactions, the average charged-hadron transverse momentum is measured to be 0.46 ± 0.01 (stat.) ± 0.01 (syst.) GeV/c at 0.9 TeV and 0.50 ± 0.01 (stat.) ± 0.01 (syst.) GeV/c at 2.36 TeV, for pseudorapidities between −2.4 and +2.4. At these energies, the measured pseudorapidity densities in the central region, dN ch /dη| |η|<0.5 , are 3.48 ± 0.02 (stat.) ± 0.13 (syst.) and 4.47 ± 0.04 (stat.) ± 0.16 (syst.), respectively. The results at 0.9 TeV are in agreement with previous measurements and confirm the expectation of near equal hadron production in pp and pp collisions. The results at 2.36 TeV represent the highest-energy measurements at a particle collider to date.
Physical Review Letters, 2010
A search for narrow resonances in the dijet mass spectrum is performed using data corresponding t... more A search for narrow resonances in the dijet mass spectrum is performed using data corresponding to an integrated luminosity of 2.9 pb −1 collected by the CMS experiment at the Large Hadron Collider. Upper limits at the 95% confidence level are presented on the product of the resonance cross section, branching fraction into dijets, and acceptance, separately for decays into quark-quark, quark-gluon, or gluon-gluon pairs. The data exclude new particles predicted in the following models at the 95% confidence level: string resonances, with mass less than 2.50 TeV, excited quarks, with mass less than 1.58 TeV, and axigluons, colorons, and E 6 diquarks, in specific mass intervals. This extends previously published limits on these models.
Biological Trace Element Research
Lead (Pb) is a trace metal element in the human body. In order to understand the hazard mechanism... more Lead (Pb) is a trace metal element in the human body. In order to understand the hazard mechanism of the elevated blood lead level on the human body, the effect of Pb2+ on the human ether-à-go-go-related gene (hERG) K+ channel in the HEK 293 cell was investigated for the first time using whole-cell patch clamp technique, molecular dynamics simulation, and quantum chemistry calculation methods. We found that Pb2+ obviously inhibits the current of the hERG K+ channel, and delays the “activation” and “deactivation” of the hERG K+ channel, indicating that Pb2+ evidently decreases the function of the K+ channel in the cell. The effect is increased with increasing the concentration of Pb2+. When the concentration of Pb2+ is 400 μg L−1, the function of the K+ channel is entirely lost. The results from the molecular dynamics simulation and quantum chemistry calculation indicated that Pb2+ can coordinate with the oxygen/sulfur atoms in the K+ channel protein, leading to the decrease in the function of the K+ channel. According to the experimental results, we suggested that once the K+ channel in the human body was irreversibly inactivated by Pb2+, it would affect the treatment and prognosis of Pb2+ intoxication.
Physical Review D, 2011
The Upsilon production cross section in proton-proton collisions at sqrt(s) = 7 TeV is measured u... more The Upsilon production cross section in proton-proton collisions at sqrt(s) = 7 TeV is measured using a data sample collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 3.1 +/- 0.3 inverse picobarns. Integrated over the rapidity range |y|<2, we find the product of the Upsilon(1S) production cross section and branching fraction to dimuons to be sigma(pp to Upsilon(1S) X) B(Upsilon(1S) to mu+ mu-) = 7.37 +/- 0.13^{+0.61}_{-0.42}\pm 0.81 nb, where the first uncertainty is statistical, the second is systematic, and the third is associated with the estimation of the integrated luminosity of the data sample. This cross section is obtained assuming unpolarized Upsilon(1S) production. If the Upsilon(1S) production polarization is fully transverse or fully longitudinal the cross section changes by about 20%. We also report the measurement of the Upsilon(1S), Upsilon(2S), and Upsilon(3S) differential cross sections as a function of transverse momentum and rapidity.
Physical Review Letters, 2011
Measurements of the total and differential cross sections dσ/dpTB and dσ/dyB for B+ mesons produc... more Measurements of the total and differential cross sections dσ/dpTB and dσ/dyB for B+ mesons produced in pp collisions at s=7TeV are presented. The data correspond to an integrated luminosity of 5.8pb-1 collected by the CMS experiment operating at the LHC. The exclusive decay B+→J/ψK+, with J/ψ→μ+μ-, is used to detect B+ mesons and to measure the production cross section as a function of pTB and yB. The total cross section for pTB>5GeV and |yB|<2.4 is measured to be 28.1±2.4±2.0±3.1μb, where the first uncertainty is statistical, the second is systematic, and the last is from the luminosity measurement.
American Journal of Physiology-heart and Circulatory Physiology, 2009
We performed the present study to determine whether hibernating myocardium is chronically protect... more We performed the present study to determine whether hibernating myocardium is chronically protected from ischemia. Myocardial tissue was rapidly excised from hibernating left anterior descending coronary regions (systolic wall thickening = 2.8 +/- 0.2 vs. 5.4 +/- 0.3 mm in remote myocardium), and high-energy phosphates were quantified by HPLC during simulated ischemia in vitro (37 degrees C). At baseline, ATP (20.1 +/- 1.0 vs. 26.7 +/- 2.1 micromol/g dry wt, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05), ADP (8.1 +/- 0.4 vs. 10.3 +/- 0.8 micromol/g, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05), and total adenine nucleotides (31.2 +/- 1.3 vs. 40.1 +/- 2.9 micromol/g, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) were depressed compared with normal myocardium, whereas total creatine, creatine phosphate, and ATP-to-ADP ratios were unchanged. During simulated ischemia, there was a marked attenuation of ATP depletion (5.6 +/- 0.9 vs. 13.7 +/- 1.7 micromol/g at 20 min in control, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) and mitochondrial respiration [145 +/- 13 vs. 187 +/- 11 ng atoms O(2).mg protein(-1).min(-1) in control (state 3), P &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05], whereas lactate accumulation was unaffected. These in vitro changes were accompanied by protection of the hibernating heart from acute stunning during demand-induced ischemia. Thus, despite contractile dysfunction at rest, hibernating myocardium is ischemia tolerant, with reduced mitochondrial respiration and slowing of ATP depletion during simulated ischemia, which may maintain myocyte viability.
European Physical Journal C, 2010
A measurement of the underlying activity in scattering processes with p T scale in the GeV region... more A measurement of the underlying activity in scattering processes with p T scale in the GeV region is performed in proton–proton collisions at sqrts=0.9\sqrt{s} = 0.9sqrts=0.9 TeV, using data collected by the CMS experiment at the LHC. Charged particle production is studied with reference to the direction of a leading object, either a charged particle or a set of charged particles forming a jet. Predictions of several QCD-inspired models as implemented in PYTHIA are compared, after full detector simulation, to the data. The models generally predict too little production of charged particles with pseudorapidity |η|<2, p T >0.5 GeV/c, and azimuthal direction transverse to that of the leading object. A measurement of the underlying activity in scattering processes with p T scale in the GeV region is performed in proton–proton collisions at sqrts=0.9\sqrt{s} = 0.9sqrts=0.9 TeV, using data collected by the CMS experiment at the LHC. Charged particle production is studied with reference to the direction of a leading object, either a charged particle or a set of charged particles forming a jet. Predictions of several QCD-inspired models as implemented in PYTHIA are compared, after full detector simulation, to the data. The models generally predict too little production of charged particles with pseudorapidity |η|<2, p T >0.5 GeV/c, and azimuthal direction transverse to that of the leading object.
Physics Letters B, 2011
A search for supersymmetry with R-parity conservation in proton-proton collisions at a centre-of-... more A search for supersymmetry with R-parity conservation in proton-proton collisions at a centre-of-mass energy of 7 TeV is presented. The data correspond to an integrated luminosity of 35 pb −1 collected by the CMS experiment at the LHC. The search is performed in events with jets and significant missing transverse energy, characteristic of the decays of heavy, pair-produced squarks and gluinos. The primary background, from standard model multijet production, is reduced by several orders of magnitude to a negligible level by the application of a set of robust kinematic requirements. With this selection, the data are consistent with the standard model backgrounds, namely tt, W + jet and Z + jet production, which are estimated from data control samples. Limits are set on the parameters of the constrained minimal supersymmetric extension of the standard model. These limits extend those set previously by experiments at the Tevatron and LEP colliders.
Physics Letters B, 2010
We present a measurement of the ratio of positive to negative muon fluxes from cosmic ray interac... more We present a measurement of the ratio of positive to negative muon fluxes from cosmic ray interactions in the atmosphere, using data collected by the CMS detector both at ground level and in the underground experimental cavern at the CERN LHC. Muons were detected in the momentum range from 5 GeV/c to 1 TeV/c. The surface flux ratio is measured to be 1.2766 ± 0.0032 (stat.) ± 0.0032 (syst.), independent of the muon momentum, below 100 GeV/c. This is the most precise measurement to date. At higher momenta the data are consistent with an increase of the charge ratio, in agreement with cosmic ray shower models and compatible with previous measurements by deep-underground experiments.
Physical Review Letters, 2010
Bose-Einstein correlations have been measured using samples of proton-proton collisions at 0.9 an... more Bose-Einstein correlations have been measured using samples of proton-proton collisions at 0.9 and 2.36 TeV center-of-mass energies, recorded by the CMS experiment at the CERN Large Hadron Collider. The signal is observed in the form of an enhancement of pairs of same-sign charged particles with small relative four-momentum. The size of the correlated particle emission region is seen to increase significantly with the particle multiplicity of the event.
Composites Part A-applied Science and Manufacturing, 2008
Polymer/carbon nanotubes nanocomposites were fabricated by an in situ polymerization process usin... more Polymer/carbon nanotubes nanocomposites were fabricated by an in situ polymerization process using multi-wall carbon nanotubes (MWNT) as filler in an epoxy polymer. Effects of curing process, mixing speed, mixing time, addition of ethanol, timing of hardener addition, etc., in the fabrication process on the electrical properties of nanocomposites have been investigated. In the fabrication process, the effective formation of macroscopic conducting network in matrix is most important to enhance the electrical properties of nanocomposites. It was found that the curing temperature and the mixing conditions are key factors in the fabrication process, which influence the formation of conducting network significantly. Therefore, careful design of these factors in the fabrication process is required to achieve high electrical performances of nanocomposites. The experimental percolation threshold of the resultant nanocomposites was around 0.1 wt%. Moreover, a statistical percolation model was built up to numerically investigate the percolation threshold. The experimental electrical conductivity increases from the percolation threshold following a percolation-like power law with the identified critical exponent t as 1.75.
Physical Review Letters, 2011
A search for pair production of first-generation scalar leptoquarks is performed in the final sta... more A search for pair production of first-generation scalar leptoquarks is performed in the final state containing two electrons and two jets using proton-proton collision data at sqrt(s)=7 TeV. The data sample used corresponds to an integrated luminosity of 33 inverse picobarns collected with the CMS detector at the CERN LHC. The number of observed events is in good agreement with the predictions for the standard model background processes, and an upper limit is set on the leptoquark pair production cross section times beta^2 as a function of the leptoquark mass, where beta is the branching fraction of the leptoquark decay to an electron and a quark. A 95% confidence level lower limit is set on the mass of a first-generation scalar leptoquark at 384 GeV for beta=1, which is the most stringent direct limit to date.
Physical Review Letters, 2011
Dijet angular distributions are measured over a wide range of dijet invariant masses in pp collis... more Dijet angular distributions are measured over a wide range of dijet invariant masses in pp collisions at sqrt(s) = 7 TeV, at the CERN LHC. The event sample, recorded with the CMS detector, corresponds to an integrated luminosity of 36 inverse picobarns. The data are found to be in good agreement with the predictions of perturbative QCD, and yield no evidence of quark compositeness. With a modified frequentist approach, a lower limit on the contact interaction scale for left-handed quarks of Lambda = 5.6 TeV (6.7 TeV) for destructive (constructive) interference is obtained at the 95% confidence level.
Carbon, 2010
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.
Physical Review Letters, 2010
A search for quark compositeness in the form of quark contact interactions, based on hadronic jet... more A search for quark compositeness in the form of quark contact interactions, based on hadronic jet pairs (dijets) produced in proton-proton collisions at s=7TeV, is described. The data sample of the study corresponds to an integrated luminosity of 2.9pb-1 collected with the CMS detector at the LHC. The dijet centrality ratio, which quantifies the angular distribution of the dijets, is measured as a function of the invariant mass of the dijet system and is found to agree with the predictions of the standard model. A statistical analysis of the data provides a lower limit on the energy scale of quark contact interactions. The sensitivity of the analysis is such that the expected limit is 2.9 TeV; because the observed value of the centrality ratio at high invariant mass is below the expectation, the observed limit is 4.0 TeV at the 95% confidence level.
Physical Review Letters, 2011
The results of the first search for long-lived gluinos produced in 7 TeV pp collisions at the CER... more The results of the first search for long-lived gluinos produced in 7 TeV pp collisions at the CERN Large Hadron Collider are presented. The search looks for evidence of long-lived particles that stop in the CMS detector and decay in the quiescent periods between beam crossings. In a dataset with a peak instantaneous luminosity of 1×1032cm-2s-1, an integrated luminosity of 10pb-1, and a search interval corresponding to 62 hours of LHC operation, no significant excess above background was observed. Limits at the 95% confidence level on gluino pair production over 13 orders of magnitude of gluino lifetime are set. For a mass difference mg˜-mχ˜10>100GeV/c2, and assuming BR(g˜→gχ˜10)=100%, mg˜<370GeV/c2 are excluded for lifetimes from 10μs to 1000 s.
Physical Review Letters, 2011
Measurements of dijet azimuthal decorrelations in pp collisions at s=7TeV using the CMS detector ... more Measurements of dijet azimuthal decorrelations in pp collisions at s=7TeV using the CMS detector at the CERN LHC are presented. The analysis is based on an inclusive dijet event sample corresponding to an integrated luminosity of 2.9pb-1. The results are compared to predictions from perturbative QCD calculations and various Monte Carlo event generators. The dijet azimuthal distributions are found to be sensitive to initial-state gluon radiation.
Basic & Clinical Pharmacology & Toxicology, 2010
Abstract: The administration of certain fluoroquinolone antibacterials has recently been linked ... more Abstract: The administration of certain fluoroquinolone antibacterials has recently been linked to QT interval prolongation, raising the clinical concerns over the cardiotoxicity of these agents. In this study, the effects of a novel fluoroquinolone, antofloxacin hydrochloride (AX) on human-ether-à-go-go-related gene (HERG) encoding potassium channels and the biophysical mechanisms of drug action were performed with whole-cell patch-clamp technique in transiently transfected HEK293 cells. The administration of AX caused voltage- and time-dependent inhibition of HERG K+ current (IHERG/MiRP1) in a concentration-dependent manner but did not markedly modify the properties of channel kinetics, including activation, inactivation, deactivation and recovery from inactivation as well. In comparison with sparfloxacin (SPX), levofloxacin lactate (LVFX), the potency of AX to inhibit HERG tail currents was the least one, with an IC50 value of 460.37 μM. By contrast, SPX was the most potent compound, displaying an IC50 value of 2.69 μM whereas LVFX showed modest potency, with an IC50 value of 43.86 μM, respectively. Taken together, our data suggest that AX only causes a minor reduction of IHERG/MiRP1 at the estimated free plasma level.
Journal of High Energy Physics, 2010
Measurements of inclusive charged-hadron transverse-momentum and pseudorapidity distributions are... more Measurements of inclusive charged-hadron transverse-momentum and pseudorapidity distributions are presented for proton-proton collisions at √ s = 0.9 and 2.36 TeV. The data were collected with the CMS detector during the LHC commissioning in December 2009. For non-single-diffractive interactions, the average charged-hadron transverse momentum is measured to be 0.46 ± 0.01 (stat.) ± 0.01 (syst.) GeV/c at 0.9 TeV and 0.50 ± 0.01 (stat.) ± 0.01 (syst.) GeV/c at 2.36 TeV, for pseudorapidities between −2.4 and +2.4. At these energies, the measured pseudorapidity densities in the central region, dN ch /dη| |η|<0.5 , are 3.48 ± 0.02 (stat.) ± 0.13 (syst.) and 4.47 ± 0.04 (stat.) ± 0.16 (syst.), respectively. The results at 0.9 TeV are in agreement with previous measurements and confirm the expectation of near equal hadron production in pp and pp collisions. The results at 2.36 TeV represent the highest-energy measurements at a particle collider to date.
Physical Review Letters, 2010
A search for narrow resonances in the dijet mass spectrum is performed using data corresponding t... more A search for narrow resonances in the dijet mass spectrum is performed using data corresponding to an integrated luminosity of 2.9 pb −1 collected by the CMS experiment at the Large Hadron Collider. Upper limits at the 95% confidence level are presented on the product of the resonance cross section, branching fraction into dijets, and acceptance, separately for decays into quark-quark, quark-gluon, or gluon-gluon pairs. The data exclude new particles predicted in the following models at the 95% confidence level: string resonances, with mass less than 2.50 TeV, excited quarks, with mass less than 1.58 TeV, and axigluons, colorons, and E 6 diquarks, in specific mass intervals. This extends previously published limits on these models.
Biological Trace Element Research
Lead (Pb) is a trace metal element in the human body. In order to understand the hazard mechanism... more Lead (Pb) is a trace metal element in the human body. In order to understand the hazard mechanism of the elevated blood lead level on the human body, the effect of Pb2+ on the human ether-à-go-go-related gene (hERG) K+ channel in the HEK 293 cell was investigated for the first time using whole-cell patch clamp technique, molecular dynamics simulation, and quantum chemistry calculation methods. We found that Pb2+ obviously inhibits the current of the hERG K+ channel, and delays the “activation” and “deactivation” of the hERG K+ channel, indicating that Pb2+ evidently decreases the function of the K+ channel in the cell. The effect is increased with increasing the concentration of Pb2+. When the concentration of Pb2+ is 400 μg L−1, the function of the K+ channel is entirely lost. The results from the molecular dynamics simulation and quantum chemistry calculation indicated that Pb2+ can coordinate with the oxygen/sulfur atoms in the K+ channel protein, leading to the decrease in the function of the K+ channel. According to the experimental results, we suggested that once the K+ channel in the human body was irreversibly inactivated by Pb2+, it would affect the treatment and prognosis of Pb2+ intoxication.
Physical Review D, 2011
The Upsilon production cross section in proton-proton collisions at sqrt(s) = 7 TeV is measured u... more The Upsilon production cross section in proton-proton collisions at sqrt(s) = 7 TeV is measured using a data sample collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 3.1 +/- 0.3 inverse picobarns. Integrated over the rapidity range |y|<2, we find the product of the Upsilon(1S) production cross section and branching fraction to dimuons to be sigma(pp to Upsilon(1S) X) B(Upsilon(1S) to mu+ mu-) = 7.37 +/- 0.13^{+0.61}_{-0.42}\pm 0.81 nb, where the first uncertainty is statistical, the second is systematic, and the third is associated with the estimation of the integrated luminosity of the data sample. This cross section is obtained assuming unpolarized Upsilon(1S) production. If the Upsilon(1S) production polarization is fully transverse or fully longitudinal the cross section changes by about 20%. We also report the measurement of the Upsilon(1S), Upsilon(2S), and Upsilon(3S) differential cross sections as a function of transverse momentum and rapidity.
Physical Review Letters, 2011
Measurements of the total and differential cross sections dσ/dpTB and dσ/dyB for B+ mesons produc... more Measurements of the total and differential cross sections dσ/dpTB and dσ/dyB for B+ mesons produced in pp collisions at s=7TeV are presented. The data correspond to an integrated luminosity of 5.8pb-1 collected by the CMS experiment operating at the LHC. The exclusive decay B+→J/ψK+, with J/ψ→μ+μ-, is used to detect B+ mesons and to measure the production cross section as a function of pTB and yB. The total cross section for pTB>5GeV and |yB|<2.4 is measured to be 28.1±2.4±2.0±3.1μb, where the first uncertainty is statistical, the second is systematic, and the last is from the luminosity measurement.
American Journal of Physiology-heart and Circulatory Physiology, 2009
We performed the present study to determine whether hibernating myocardium is chronically protect... more We performed the present study to determine whether hibernating myocardium is chronically protected from ischemia. Myocardial tissue was rapidly excised from hibernating left anterior descending coronary regions (systolic wall thickening = 2.8 +/- 0.2 vs. 5.4 +/- 0.3 mm in remote myocardium), and high-energy phosphates were quantified by HPLC during simulated ischemia in vitro (37 degrees C). At baseline, ATP (20.1 +/- 1.0 vs. 26.7 +/- 2.1 micromol/g dry wt, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05), ADP (8.1 +/- 0.4 vs. 10.3 +/- 0.8 micromol/g, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05), and total adenine nucleotides (31.2 +/- 1.3 vs. 40.1 +/- 2.9 micromol/g, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) were depressed compared with normal myocardium, whereas total creatine, creatine phosphate, and ATP-to-ADP ratios were unchanged. During simulated ischemia, there was a marked attenuation of ATP depletion (5.6 +/- 0.9 vs. 13.7 +/- 1.7 micromol/g at 20 min in control, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) and mitochondrial respiration [145 +/- 13 vs. 187 +/- 11 ng atoms O(2).mg protein(-1).min(-1) in control (state 3), P &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05], whereas lactate accumulation was unaffected. These in vitro changes were accompanied by protection of the hibernating heart from acute stunning during demand-induced ischemia. Thus, despite contractile dysfunction at rest, hibernating myocardium is ischemia tolerant, with reduced mitochondrial respiration and slowing of ATP depletion during simulated ischemia, which may maintain myocyte viability.
European Physical Journal C, 2010
A measurement of the underlying activity in scattering processes with p T scale in the GeV region... more A measurement of the underlying activity in scattering processes with p T scale in the GeV region is performed in proton–proton collisions at sqrts=0.9\sqrt{s} = 0.9sqrts=0.9 TeV, using data collected by the CMS experiment at the LHC. Charged particle production is studied with reference to the direction of a leading object, either a charged particle or a set of charged particles forming a jet. Predictions of several QCD-inspired models as implemented in PYTHIA are compared, after full detector simulation, to the data. The models generally predict too little production of charged particles with pseudorapidity |η|<2, p T >0.5 GeV/c, and azimuthal direction transverse to that of the leading object. A measurement of the underlying activity in scattering processes with p T scale in the GeV region is performed in proton–proton collisions at sqrts=0.9\sqrt{s} = 0.9sqrts=0.9 TeV, using data collected by the CMS experiment at the LHC. Charged particle production is studied with reference to the direction of a leading object, either a charged particle or a set of charged particles forming a jet. Predictions of several QCD-inspired models as implemented in PYTHIA are compared, after full detector simulation, to the data. The models generally predict too little production of charged particles with pseudorapidity |η|<2, p T >0.5 GeV/c, and azimuthal direction transverse to that of the leading object.
Physics Letters B, 2011
A search for supersymmetry with R-parity conservation in proton-proton collisions at a centre-of-... more A search for supersymmetry with R-parity conservation in proton-proton collisions at a centre-of-mass energy of 7 TeV is presented. The data correspond to an integrated luminosity of 35 pb −1 collected by the CMS experiment at the LHC. The search is performed in events with jets and significant missing transverse energy, characteristic of the decays of heavy, pair-produced squarks and gluinos. The primary background, from standard model multijet production, is reduced by several orders of magnitude to a negligible level by the application of a set of robust kinematic requirements. With this selection, the data are consistent with the standard model backgrounds, namely tt, W + jet and Z + jet production, which are estimated from data control samples. Limits are set on the parameters of the constrained minimal supersymmetric extension of the standard model. These limits extend those set previously by experiments at the Tevatron and LEP colliders.
Physics Letters B, 2010
We present a measurement of the ratio of positive to negative muon fluxes from cosmic ray interac... more We present a measurement of the ratio of positive to negative muon fluxes from cosmic ray interactions in the atmosphere, using data collected by the CMS detector both at ground level and in the underground experimental cavern at the CERN LHC. Muons were detected in the momentum range from 5 GeV/c to 1 TeV/c. The surface flux ratio is measured to be 1.2766 ± 0.0032 (stat.) ± 0.0032 (syst.), independent of the muon momentum, below 100 GeV/c. This is the most precise measurement to date. At higher momenta the data are consistent with an increase of the charge ratio, in agreement with cosmic ray shower models and compatible with previous measurements by deep-underground experiments.
Physical Review Letters, 2010
Bose-Einstein correlations have been measured using samples of proton-proton collisions at 0.9 an... more Bose-Einstein correlations have been measured using samples of proton-proton collisions at 0.9 and 2.36 TeV center-of-mass energies, recorded by the CMS experiment at the CERN Large Hadron Collider. The signal is observed in the form of an enhancement of pairs of same-sign charged particles with small relative four-momentum. The size of the correlated particle emission region is seen to increase significantly with the particle multiplicity of the event.
Composites Part A-applied Science and Manufacturing, 2008
Polymer/carbon nanotubes nanocomposites were fabricated by an in situ polymerization process usin... more Polymer/carbon nanotubes nanocomposites were fabricated by an in situ polymerization process using multi-wall carbon nanotubes (MWNT) as filler in an epoxy polymer. Effects of curing process, mixing speed, mixing time, addition of ethanol, timing of hardener addition, etc., in the fabrication process on the electrical properties of nanocomposites have been investigated. In the fabrication process, the effective formation of macroscopic conducting network in matrix is most important to enhance the electrical properties of nanocomposites. It was found that the curing temperature and the mixing conditions are key factors in the fabrication process, which influence the formation of conducting network significantly. Therefore, careful design of these factors in the fabrication process is required to achieve high electrical performances of nanocomposites. The experimental percolation threshold of the resultant nanocomposites was around 0.1 wt%. Moreover, a statistical percolation model was built up to numerically investigate the percolation threshold. The experimental electrical conductivity increases from the percolation threshold following a percolation-like power law with the identified critical exponent t as 1.75.
Physical Review Letters, 2011
A search for pair production of first-generation scalar leptoquarks is performed in the final sta... more A search for pair production of first-generation scalar leptoquarks is performed in the final state containing two electrons and two jets using proton-proton collision data at sqrt(s)=7 TeV. The data sample used corresponds to an integrated luminosity of 33 inverse picobarns collected with the CMS detector at the CERN LHC. The number of observed events is in good agreement with the predictions for the standard model background processes, and an upper limit is set on the leptoquark pair production cross section times beta^2 as a function of the leptoquark mass, where beta is the branching fraction of the leptoquark decay to an electron and a quark. A 95% confidence level lower limit is set on the mass of a first-generation scalar leptoquark at 384 GeV for beta=1, which is the most stringent direct limit to date.
Physical Review Letters, 2011
Dijet angular distributions are measured over a wide range of dijet invariant masses in pp collis... more Dijet angular distributions are measured over a wide range of dijet invariant masses in pp collisions at sqrt(s) = 7 TeV, at the CERN LHC. The event sample, recorded with the CMS detector, corresponds to an integrated luminosity of 36 inverse picobarns. The data are found to be in good agreement with the predictions of perturbative QCD, and yield no evidence of quark compositeness. With a modified frequentist approach, a lower limit on the contact interaction scale for left-handed quarks of Lambda = 5.6 TeV (6.7 TeV) for destructive (constructive) interference is obtained at the 95% confidence level.
Carbon, 2010
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.
Physical Review Letters, 2010
A search for quark compositeness in the form of quark contact interactions, based on hadronic jet... more A search for quark compositeness in the form of quark contact interactions, based on hadronic jet pairs (dijets) produced in proton-proton collisions at s=7TeV, is described. The data sample of the study corresponds to an integrated luminosity of 2.9pb-1 collected with the CMS detector at the LHC. The dijet centrality ratio, which quantifies the angular distribution of the dijets, is measured as a function of the invariant mass of the dijet system and is found to agree with the predictions of the standard model. A statistical analysis of the data provides a lower limit on the energy scale of quark contact interactions. The sensitivity of the analysis is such that the expected limit is 2.9 TeV; because the observed value of the centrality ratio at high invariant mass is below the expectation, the observed limit is 4.0 TeV at the 95% confidence level.
Physical Review Letters, 2011
The results of the first search for long-lived gluinos produced in 7 TeV pp collisions at the CER... more The results of the first search for long-lived gluinos produced in 7 TeV pp collisions at the CERN Large Hadron Collider are presented. The search looks for evidence of long-lived particles that stop in the CMS detector and decay in the quiescent periods between beam crossings. In a dataset with a peak instantaneous luminosity of 1×1032cm-2s-1, an integrated luminosity of 10pb-1, and a search interval corresponding to 62 hours of LHC operation, no significant excess above background was observed. Limits at the 95% confidence level on gluino pair production over 13 orders of magnitude of gluino lifetime are set. For a mass difference mg˜-mχ˜10>100GeV/c2, and assuming BR(g˜→gχ˜10)=100%, mg˜<370GeV/c2 are excluded for lifetimes from 10μs to 1000 s.
Physical Review Letters, 2011
Measurements of dijet azimuthal decorrelations in pp collisions at s=7TeV using the CMS detector ... more Measurements of dijet azimuthal decorrelations in pp collisions at s=7TeV using the CMS detector at the CERN LHC are presented. The analysis is based on an inclusive dijet event sample corresponding to an integrated luminosity of 2.9pb-1. The results are compared to predictions from perturbative QCD calculations and various Monte Carlo event generators. The dijet azimuthal distributions are found to be sensitive to initial-state gluon radiation.
Basic & Clinical Pharmacology & Toxicology, 2010
Abstract: The administration of certain fluoroquinolone antibacterials has recently been linked ... more Abstract: The administration of certain fluoroquinolone antibacterials has recently been linked to QT interval prolongation, raising the clinical concerns over the cardiotoxicity of these agents. In this study, the effects of a novel fluoroquinolone, antofloxacin hydrochloride (AX) on human-ether-à-go-go-related gene (HERG) encoding potassium channels and the biophysical mechanisms of drug action were performed with whole-cell patch-clamp technique in transiently transfected HEK293 cells. The administration of AX caused voltage- and time-dependent inhibition of HERG K+ current (IHERG/MiRP1) in a concentration-dependent manner but did not markedly modify the properties of channel kinetics, including activation, inactivation, deactivation and recovery from inactivation as well. In comparison with sparfloxacin (SPX), levofloxacin lactate (LVFX), the potency of AX to inhibit HERG tail currents was the least one, with an IC50 value of 460.37 μM. By contrast, SPX was the most potent compound, displaying an IC50 value of 2.69 μM whereas LVFX showed modest potency, with an IC50 value of 43.86 μM, respectively. Taken together, our data suggest that AX only causes a minor reduction of IHERG/MiRP1 at the estimated free plasma level.