Biomedical subjects

S Behari

Publications and source records attributed to S Behari.

At least 55 records · Page 3Linked to original sources

PubMed2005

Measurement of charged-particle multiplicities in gluon and quark jets in pp collisions at square root of s = 1.8 TeV.

We report the first largely model independent measurement of charged particle multiplicities in quark and gluon jets, Nq and Ng, produced at the Fermilab Tevatron in pp collisions with a center-of-mass energy of 1.8 TeV and recorded by the Collider Detector at Fermilab. The measurements are made for jets with average energies of 41 and 53 GeV by counting charged particle tracks in cones with opening angles of theta(c) = 0.28, 0.36, and 0.47 rad around the jet axis. The corresponding jet hardness Q = Ejet theta c varies in the range from 12 to 25 GeV. At Q = 19.2 GeV, the ratio of multiplicities r = Ng/Nq is found to be 1.64+/-0.17, where statistical and systematic uncertainties are added in quadrature. The results are in agreement with resummed perturbative QCD calculations.

Journal Article↗

PubMed2005

Measurement of partial widths and search for direct CP violation in D0 meson decays to K-K+ and pi-pi+.

We present a measurement of relative partial widths and decay rate CP asymmetries in K-K+ and pi(-)pi(+) decays of D0 mesons produced in pp collisions at sqrt[s]=1.96 TeV. We use a sample of 2x10(5) D(*+)-->D0pi(+) (and charge conjugate) decays with the D0 decaying to K-pi(+), K-K+, and pi(-)pi(+), corresponding to 123 pb(-1) of data collected by the Collider Detector at Fermilab II experiment at the Fermilab Tevatron collider. No significant direct CP violation is observed. We measure Gamma(D0-->K-K+)/Gamma(D0-->K-pi(+))=0.0992+/-0.0011+/-0.0012, Gamma(D0-->pi(-)pi(+))/Gamma(D0-->K-pi(+))=0.035 94+/-0.000 54+/-0.000 40, A(CP)(K-K+)=(2.0+/-1.2+/-0.6)%, and A(CP)(pi(-)pi(+))=(1.0+/-1.3+/-0.6)%, where, in all cases, the first uncertainty is statistical and the second is systematic.

Journal Article↗

PubMed2005

Search for excited and exotic electrons in the egamma decay channel in pp collisions at sqrt[s] = 1.96 TeV.

We present a search for excited and exotic electrons (e(*)) decaying to an electron and a photon, both with high transverse momentum. We use 202 pb(-1) of data collected in pp collisions at sqrt[s] = 1.96 TeV with the Collider Detector at Fermilab II detector. No signal above standard model expectation is seen for associated ee(*) production. We discuss the e(*) sensitivity in the parameter space of the excited electron mass M(e(*)) and the compositeness energy scale Lambda. In the contact interaction model, we exclude 132 GeV/c(2)<M(e(*))<879 GeV/c(2) for Lambda = M(e(*)) at 95% confidence level (C.L.). In the gauge-mediated model, we exclude 126 GeV/c(2) < M(e(*)) < 430 GeV/c(2) at 95% C.L. for the phenomenological coupling f/Lambda approximately 10(-2) GeV-1.

Journal Article↗

PubMed2005

Measurement of the lifetime difference between Bs mass eigenstates.

We present measurements of the lifetimes and polarization amplitudes for B(0)(s)-->J/psiphi and B(0)(d)-->J/psiK(*0) decays. Lifetimes of the heavy and light mass eigenstates in the B(0)(s) system are separately measured for the first time by determining the relative contributions of amplitudes with definite CP as a function of the decay time. Using 203+/-15 B(0)(s) decays we obtain tau(L) = (1.05(+0.16)(-0.13) +/- 0.02) ps and tau(H) = (2.07(+0.58)(-0.46) +/- 0.03) ps. Expressed in terms of the difference DeltaGamma(s) and average Gamma(s), of the decay rates of the two eigenstates, the results are DeltaGamma(s)/Gamma(s) = (65(+25)(-33) +/- 1)% and DeltaGamma(s) = (0.47(+0.19)(-0.24) +/- 0.01) ps(-1).

Journal Article↗

PubMed2005

First measurements of inclusive W and Z cross sections from run II of the fermilab tevatron collider.

We report the first measurements of inclusive W and Z cross sections times leptonic branching ratios for pp collisions at square root[s]=1.96 TeV, based on their decays to electrons and muons. The data correspond to an integrated luminosity of 72 pb(-1) recorded with the CDF detector at the Fermilab Tevatron. We test e-mu universality in W decays, and we measure the ratio of leptonic W and Z rates from which the leptonic branching fraction B(W-->lnu) can be extracted as well as an indirect value for the total width of the W and the Cabibbo-Kobayashi-Maskawa matrix element, |V(cs)|.

Journal Article↗

PubMed2005

Measurement of Wgamma and Zgamma production in pp collisions at square root s=1.96 TeV.

The standard model predictions for Wgamma and Zgamma production are tested using an integrated luminosity of 200 pb(-1) of pp collision data collected at the Collider Detector at Fermilab. The cross sections are measured by selecting leptonic decays of the W and Z bosons, and photons with transverse energy ET>7 GeV that are well separated from leptons. The production cross sections and kinematic distributions for the Wgamma and Zgamma data are compared to SM predictions.

Journal Article↗

PubMed2005

Intracranial aneurysms in patients 18 years of age or under, are they different from aneurysms in adult population?

BACKGROUND: Intracranial aneurysms are extremely uncommon in the first two decades of life. This study was undertaken to assess the clinicoradiological features and surgical outcome of intracranial aneurysms in patients less than or equal to 18 years of age; and, to highlight the differences between these and intracranial aneurysms seen in adult patients. METHODS AND MATERIAL: Twenty-two patients, 18 years of age or under (male:female ratio=1.75:1; mean age 14.18+/-3.8 years, age range 5 to 18 years) and 451 adult patients aged older than 18 years (male:female ratio=1:1.05; mean age 48.21+/-12.71 years, age range, 19 to 81 years) were treated for intracranial aneurysms at our center between January 1991 and July 2003. The univariate statistical analysis was used to compare differences between the two groups. FINDINGS: The patients under 18 years constituted 4.6% of the total patient population having intracranial aneurysms. The incidence of associated medical diseases was greater in patients under 18 years than in the adults (9% versus 0.26%, p<0.05). The incidence of seizures was more than double in patients under 18 years (36% versus 17%, p<0.05). The incidence of intracerebral haematoma (ICH; 41% versus 22.5%, p>0.05), intraventricular haemorrhage (IVH; 45% versus 34%, p>0.05), and hydrocephalus (36% versus 25%, p>0.05) were higher in patients under 18 years. In adult patients, anterior communicating artery (AcoA) and in children, ICA bifurcation were the most frequent sites of aneurysm formation respectively (p<0.05). The incidence of giant aneurysms was nearly double in children (13.6% versus 6.5%, p>0.05). The incidence of clinical vasospasm was almost the same in both groups. The overall outcome was favourable in 82% of patients under 18 years and 58.8% in adults. The management mortality in patients under 18 years was 9.1%, while in the adult patients, it was 19%. CONCLUSION: In patients under 18 years of age, there was a definite male predominance; a higher incidence of seizures; and, the ICA bifurcation formed the most frequent site of intracranial aneurysms. In adults, AcoA a was the commonest site. Rebleeding and delayed ischaemic deficits were the major causes of morbidity. Favorable outcome after surgery in young patients was better in comparison to their adult counterparts.

Adolescent↗

PubMed2005

Proximal migration of a lumboperitoneal unishunt system.

Proximal migration of a lumboperitoneal (LP) shunt is a rare complication associated with unishunt systems. We report three cases with a hypothesis that raised intra-abdominal pressure may be a factor responsible for the proximal migration of a LP unishunt. A rare case of proximal migration of LP shunt into the quadrigeminal cistern is also reported.

Adult↗

PubMed2005

Giant presacral neuro-enteric cyst with anomalous sacrum in an adult patient.

A rare case of an adult patient with a giant neuro-enteric cyst in a presacral location is reported. It had unique histological features of a stratified squamous epithelial lining with neuro-epithelial and smooth muscle components. There was associated sacral dysgenesis with spina bifida. The possible pathogenesis of this entity is discussed.

Abortion, Induced↗

PubMed2004

Search for doubly charged Higgs bosons decaying to dileptons in pp collisions at square root of s=1.96 TeV.

We present the results of a search for doubly charged Higgs bosons (H+/-+/-) decaying to dileptons (ll(')) using approximately 240 pb(-1) of pp collision data collected by the CDF II experiment at the Fermilab Tevatron. In our search region, given by same-sign ll(') mass m(ll('))>80 GeV/c(2) (100 GeV/c(2) for ee channel), we observe no evidence for H+/-+/- production. We set limits on sigma(pp -->H++H---->l(+)l('+)l(-)l('-)) as a function of the mass of the H+/-+/- and the chirality of its couplings. Assuming exclusive same-sign dilepton decays, we derive lower mass limits on H(+/-+/-)(L) of 133, 136, and 115 GeV/c(2) in the ee, mumu, and emu channels, respectively, and a lower mass limit of 113 GeV/c(2) on H(+/-+/-)(R) in the mumu channel, all at the 95% confidence level.

Journal Article↗

PubMed2004

Inclusive double-pomeron exchange at the fermilab tevatron p p collider.

We report results from a study of events with a double-Pomeron exchange topology produced in p p collisions at sqrt[s]=1800 GeV. The events are characterized by a leading antiproton and a large rapidity gap on the outgoing proton side. We find that the differential production cross section agrees in shape with predictions based on Regge theory and factorization, and that the ratio of double-Pomeron exchange to single diffractive production rates is relatively unsuppressed as compared to the O(10) suppression factor previously measured in single diffractive production.

Journal Article↗

PubMed2004

Measurement of the tt production cross section in pp collisions at sqrt[s]=1.96 TeV using dilepton events.

We report a measurement of the tt production cross section using dilepton events with jets and missing transverse energy in pp collisions at a center-of-mass energy of 1.96 TeV. Using a 197+/-12 pb(-1) data sample recorded by the upgraded Collider Detector at Fermilab, we use two complementary techniques to select candidate events. We compare the number of observed events and selected kinematical distributions with the predictions of the standard model and find good agreement. The combined result of the two techniques yields a tt production cross section of 7.0(+2.4)(-2.1)(stat)+1.6-1.1(syst)+/-0.4(lum) pb.

Journal Article↗

PubMed2004

Observation of the narrow state X(3872)-->J/psipi+pi- in pp collisions at sqaure root of s=1.96 TeV.

We report the observation of a narrow state decaying into J/psipi+pi- and produced in 220 pb(-1) of p p-bar collisions at =1.96 Tesqaure root of sV in the CDF II experiment. We observe 730+/-90 decays. The mass is measured to be 3871.3+/-0.7(stat)+/-0.4(syst) MeV/c2, with an observed width consistent with the detector resolution. This is in agreement with the recent observation by the Belle Collaboration of the X(3872) meson.

Journal Article↗

PubMed2004

Inclusive search for anomalous production of high-pT like-sign lepton pairs in pp collisions at square root s = 1.8 TeV.

We report on a search for anomalous production of events with at least two charged, isolated, like-sign leptons, each with pT > 11 GeV/c using a 107 pb(-1) sample of 1.8 TeV pp collisions collected by the CDF detector. We define a signal region containing low background from standard model processes. To avoid bias, we fix the final cuts before examining the event yield in the signal region using control regions to test the Monte Carlo predictions. We observe no events in the signal region, consistent with an expectation of 0.63(+0.84)(-0.07) events. We present 95% confidence level limits on new physics processes in both a signature-based context as well as within a representative minimal supergravity (tanbeta = 3) model.

Journal Article↗

PubMed2004

Search for B0s-->micro+micro- and B0d-->micro+micro- decays in pp collisions at square root s = 1.96 TeV.

We report on a search for B(0)(s)-->micro(+)micro(-) and B(0)(d)-->micro(+)micro(-) decays in pp collisions at square root of s=1.96 TeV using 171 pb(-1) of data collected by the CDF II experiment at the Fermilab Tevatron Collider. The decay rates of these rare processes are sensitive to contributions from physics beyond the standard model. One event survives all our selection requirements, consistent with the background expectation. We derive branching ratio limits of B(B(0)(s)-->micro(+)micro(-))<5.8x10(-7) and B(B(0)(d)-->micro(+)micro(-))<1.5x10(-7) at 90% confidence level.

Journal Article↗

PubMed2004

Search for Kaluza-Klein graviton emission in pp collisions at square root[s] = 1.8 TeV using the missing energy signature.

We report on a search for direct Kaluza-Klein graviton production in a data sample of 84 pb(-1) of ppmacr; collisions at sqrt[s]=1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and one or two high energy jets. We compare the data with the predictions from a (3+1+n)-dimensional Kaluza-Klein scenario in which gravity becomes strong at the TeV scale. At 95% confidence level (C.L.) for n=2, 4, and 6 we exclude an effective Planck scale below 1.0, 0.77, and 0.71 TeV, respectively.

Journal Article↗

PubMed2004

Search for pair production of scalar top quarks in R-parity violating decay modes in pp collisions at square root of s=1.8 TeV.

We present the results of a search for pair production of scalar top quarks (t(1)) in an R-parity violating supersymmetry scenario in 106 pb(-1) of pp collisions at square root of s=1.8 TeV collected by the Collider Detector at Fermilab. In this mode each t(1) decays into a tau lepton and a b quark. We search for events with two tau's, one decaying leptonically (e or mu) and one decaying hadronically, and two jets. No candidate events pass our final selection criteria. We set a 95% confidence level lower limit on the t(1) mass at 122 GeV/c(2) for Br(t(1)-->tau b)=1.

Journal Article↗

PubMed2004

C3-4 level cervical spondylotic myelopathy.

Cervical spondylotic myelopathy (CSM) is uncommon at the C3-4 level. Fourteen patients with C3-4 CSM were treated over a period of 3 years. The radiological factors contributing to CSM at the C3-4 level were studied. These factors included the assessment of static and dynamic canal diameters, retrolisthesis, posterior osteophytes and degenerative spinal segmental fusion on plain X-rays; and, the antero-posterior cord compression ratio (APCR) on magnetic resonance imaging (MRI). The clinical status of the patients was assessed by the modified Japanese orthopedic association scale (mJOAS). The mean difference between the static and dynamic canal diameters was statistically significant at C3-4 (p < 0.01). The APCR obtained at different levels showed a significant compression at the C3-4 level in comparison to the lower level. There was a correlation between the APCR and the preop mJOAS, r=0.6 (p< 0.05). The mean mJOAS improved from 9.35 to 14.35 at follo-up. The recovery rate calculated using the modified Hirabayashi rate was 66.9%. Degenerative changes at lower cervical segments predispose to increased mobility and spondylotic changes at the C3-4 level. The patients in this study were young as compared to those reported in the international literature.

Cervical Vertebrae↗