Precision Determination of the Top Quark Mass

The CDF and D0 collaborations have updated their measurements of the mass of the top quark using proton-antiproton collisions at sqrt{s}=1.96TeV produced at the Tevatron. The uncertainties in each of the of top-antitop decay channels have been reduced. The new Tevatron average for the mass of the top quark based on about 1/fb of data per experiment is 170.9+-1.8GeV/c^2.Comment: 14 pages, 4 figures; LaTeX2e, 8 .eps files, uses LaThuileFPSpro.sty (included). To appear in the proceedings of the 21st Rencontres des Physique de la Vallee d'Aoste, La Thuile, March 4-10, 200

Performance of the CDF Calorimeter Simulation in Tevatron Run II

The CDF experiment is successfully collecting data from ppbar collisions at the Tevatron in Run II. As the data samples are getting larger, systematic uncertainties due to the measurement of the jet energy scale assessed using the calorimeter simulation have become increasingly important. In many years of operation, the collaboration has gained experience with GFLASH, a fast parametrization of electromagnetic and hadronic showers used for the calorimeter simulation. We present the performance of the calorimeter simulation and report on recent improvements based on a refined in situ tuning technique. The central calorimeter response is reproduced with a precision of 1-2%.Comment: 8 pages, 4 figures; LaTeX2e, 10 .eps files, uses aipproc.cls, aipxfm.sty and aip-6s.clo (included). Contribution to the Proceedings of the 12th International Conference on Calorimetry in High Energy Physics (CALOR06), June 5-9, 2006, Chicago (IL), USA. To be published by American Institute of Physics (AIP

Utility of a thematic network in primary health care: a controlled interventional study in a rural area

BACKGROUND: UniNet is an Internet-based thematic network for a virtual community of users (VCU). It supports a virtual multidisciplinary community for physicians, focused on the improvement of clinical practice. This is a study of the effects of a thematic network such as UniNet on primary care medicine in a rural area, specifically as a platform of communication between specialists at the hospital and doctors in the rural area. METHODS: In order to study the effects of a thematic network such as UniNet on primary care medicine in a rural area, we designed an interventional study that included a control group. The measurements included the number of patient displacements due to disease, number of patient hospital stays and the number of prescriptions of drugs of low therapeutic utility and generic drug prescriptions by doctors. These data were analysed and compared with those of the control center. RESULTS: Our study showed positive changes in medical practice, reflected in the improvement of the evaluated parameters in the rural health area where the interventional study was carried out, compared with the control area. We discuss the strengths and weaknesses of UniNet as a potential medium to improve the quality of medical care in rural areas. CONCLUSION: The rural doctors had an effective, useful, user-friendly and cheap source of medical information that may have contributed to the improvement observed in the medical quality indices

Measurement of the Lifetime Difference Between B_s Mass Eigenstates

We present measurements of the lifetimes and polarization amplitudes for B_s --> J/psi phi and B_d --> J/psi K*0 decays. Lifetimes of the heavy (H) and light (L) mass eigenstates in the B_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_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) inverse ps.Comment: 8 pages, 3 figures, 2 tables; as published in Physical Review Letters on 16 March 2005; revisions are for length and typesetting only, no changes in results or conclusion

Studien zur Quantenchromodynamik und Messung der starken Kopplungskonstanten alpha_S bei sqrt{s}=14-44 GeV mit dem JADE-Detektor

A reanalysis of hadronic final states of e+e- annihilation data collected with the JADE detector at the PETRA storage ring (1979-1986) is presented. This thesis focuses on perturbative and non-perturbative aspects of Quantum Chromodynamics (QCD), in particular measurements of the coupling constant alpha_S of the strong interaction and the experimental investigation of power corrections to event shapes. Major parts of the original detector simulation and offline event reconstruction software (which are partially older than 20 years) were successfully adapted and reactivated on current computer platforms. Due to the good performance of the programs, reasonable measurements of event shape observables are now possible at all PETRA energies. The differential cross sections of the variables thrust T, heavy jet mass M_H, the wide and total jet broadening B_W and B_T, respectively, the C parameter and the differential 2-jet rate in the Durham scheme were determined at centre-of-mass energies sqrt{S}= 14-44GeV. The distributions were compared with the predictions of corresponding phenomenological hadronisation models previously tuned to LEP data at the Z0 mass scale, sqrt{S}=M_Z. The parton shower and string fragmentation model implemented in PYTHIA/JETSET is found to be well capable of describing event shapes of hadronic final states down to sqrt{S}= 14 GeV. The performance of the models ARIADNE (colour dipole scheme) and HERWIG (cluster fragmentation), however, is more moderate, and COJETS (independent fragmentation) is clearly disfavoured by the data. Obviously the model parameters of these generators need a retune at lower centre-of-mass energies. From the measured event shapes, the strong coupling constant alpha_S was extracted by fits of the most complete perturbative calculations for the differential distributions available so far, namely a combination of O(alpha_S**2) and resummed NLLA calculations. The predictions which were folded with the hadronisation models agree well with the data in most cases and allow consistent determinations of alpha_S at all PETRA energies. The final results with total errors, alpha_S(14.0 GeV)= 0.1704+0.0206-0.0171, alpha_S(22.0 GeV)= 0.1513+0.0144-0.0121, alpha_S(34.8 GeV)= 0.1431+0.0118-0.0096, alpha_S(38.3 GeV)= 0.1397+0.0108-0.0087, and alpha_S(43.8 GeV)= 0.1306+0.0096-0.0080, are substantially more precise than former PETRA measurements and are also in good agreement with the theoretical prediction for alpha_S(sqrt{s}) based on the world average value for alpha_S{M_Z}. The errors are dominated by renormalisation scale and hadronisation uncertainties. Using the new PETRA values and corresponding LEP results at sqrt{S}>=M_Z, the QCD expectation for the energy evolution of alpha_S can be verified more significantly on the basis of a homogeneous analysis technique within a wide energy range of the e+e- continuum. Power corrections proportional to 1/sqrt{s} based on an analytical ansatz by Dokshitzer, Marchesini and Webber (DMW) were investigated as a promising alternative approach to describe non-perturbative effects in event shapes. Besides alpha_S, the model depends only on one additional free parameter, the 0'th moment alpha_0(muI) of the physical strong coupling constant alpha_S(mu) in the energy region mu=0...muI around the Landau pole. In addition to the JADE data, also measurements of other experiments up to sqrt{S}= 189 GeV were considered for experimental tests. Except for some discrepancies observed for the less inclusive quantities (B_W and M_H) in particular at lower centre-of-mass energies, the major parts of the overall event shape spectra are reproduced well. From global fits to differential distributions and mean values, the free parameters alpha_S and alpha_0 were simultaneously determined. The combined results (with total errors) are alpha_S(M_Z)= 0.1126+0.0058-0.0048, alpha_0(2 GeV)= 0.542+0.090-0.068 (distributions), alpha_S(M_Z)= 0.1187+0.0031-0.0021, alpha_0(2 GeV)= 0.485+0.066-0.045 (means). Moreover, the predicted universality of alpha_0 which is an essential ingredient of the DMW model has been established experimentally within the systematic uncertainties

The Dioxin Receptor Regulates the Constitutive Expression of the Vav3 Proto-Oncogene and Modulates Cell Shape and Adhesion

The dioxin receptor (AhR) modulates cell plasticity and migration, although the signaling involved remains unknown. Here, we report a mechanism that integrates AhR into these cytoskeleton-related functions. Immortalized and mouse embryonic fibroblasts lacking AhR (AhR−/−) had increased cell area due to spread cytoplasms that reverted to wild-type morphology upon AhR re-expression. The AhR-null phenotype included increased F-actin stress fibers, depolarized focal adhesions, and enhanced spreading and adhesion. The cytoskeleton alterations of AhR−/− cells were due to down-regulation of constitutive Vav3 expression, a guanosine diphosphate/guanosine triphosphate exchange factor for Rho/Rac GTPases and a novel transcriptional target of AhR. AhR was recruited to the vav3 promoter and maintained constitutive mRNA expression in a ligand-independent manner. Consistently, AhR−/− fibroblasts had reduced Rac1 activity and increased activation of the RhoA/Rho kinase (Rock) pathway. Pharmacological inhibition of Rac1 shifted AhR+/+ fibroblasts to the null phenotype, whereas Rock inhibition changed AhR-null cells to the AhR+/+ morphology. Knockdown of vav3 transcripts by small interfering RNA induced cytoskeleton defects and changes in adhesion and spreading mimicking those of AhR-null cells. Moreover, vav3−/− MEFs, as AhR−/− mouse embryonic fibroblasts, had increased cell area and enhanced stress fibers. By modulating Vav3-dependent signaling, AhR could regulate cell shape, adhesion, and migration under physiological conditions and, perhaps, in certain pathological states

Evidence for B-s(0)->phi phi decay and measurements of branching ratio and A(CP) for B+->phi K+

We present the first evidence of charmless decays of the $B_s^0$ meson, the decay \phiphi, and a measurement of the Branching Ratio \BR(\phiphi) using $180 {\rm pb}^{-1}$ of data collected by the \cdfii experiment at the Fermilab Tevatron collider. In addition, the BR and direct CP asymmetry for the \phik\ decay are measured. We obtain: \BR (\phiphi) = (14 \ase{6}{5}(stat.) \pm 6(syst.)) \times 10^{-6}, \BR (\phik) = (7.6 \pm 1.3(stat.) \pm 0.6(syst.)) \times 10^{-6}, and \ACP(\phik) = -0.07 \pm 0.17 (stat.) \ase{0.03}{0.02} (syst.). Both decays are governed in the Standard Model by second order (penguin) b \myto s\bar{s}s amplitudes.Comment: Submitted to Physical Review Letters Fixed few typos plus additional comments to introduction suggested by referee'

Measurement of the forward-backward charge asymmetry from <em><strong>W</strong>→eν</em> production in <em>pp</em> collisions at s√=1.96 TeV

We report a measurement of the forward-backward charge asymmetry of electrons from W boson decays in pp¯ collisions at s√=1.96   TeV using a data sample of 170   pb−1 collected by the Collider Detector at Fermilab. The asymmetry is measured as a function of electron rapidity and transverse energy and provides new input on the momentum fraction dependence of the u and d quark parton distribution functions within the proton