3,656 research outputs found

    Recent BES measurements and the hadronic contribution to the QED vacuum polarization

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    We have updated our evaluation of the hadronic contribution to the running of the QED fine structure constant using the recent precise measurements of the e+e- annihilation at the center-of-mass (c.m.s.) energy region between 2.6 and 3.65 GeV performed by the BES collaboration. In the low energy region, around the rho resonance, we include the recent measurements from the BABAR, CDM-2, KLOE and SND collaborations. We obtain Delta alpha (5)_had (s) = 0.02750 +/- 0.00033 at s = m_Z^2.Comment: 3 pages, 1 figur

    WW Cross-sections and Distributions

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    We present the results obtained by the "WW Cross-sections and Distributions" working group during the CERN Workshop "Physics at LEP2" (1994/1995)Comment: 61 pages, tar'ed gzip'ed uuencoded files, LaTeX, 4 Postscript figures. To appear in "Physics at LEP2", G.Altarelli and F.Zwirner eds., CERN Report 199

    On the Properties of Two Pulses Propagating Simultaneously in Different Dispersion Regimes in a Nonlinear Planar Waveguide

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    Properties of two pulses propagating simultaneously in different dispersion regimes, anomalous and normal, in a Kerr-type planar waveguide are studied in the framework of the nonlinear Schroedinger equation. Catastrophic self-focusing and spatio-temporal splitting of the pulses is investigated. For the limiting case when the dispersive term of the pulse propagating in the normal dispersion regime can be neglected an indication of a possibility of a stable self-trapped propagation of both pulses is obtained.Comment: 18 pages (including 15 eps figures

    Evidence for Bosonic Electroweak Corrections in the Standard Model

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    We present strong indirect evidence for the contribution of bosonic electroweak corrections in the Standard Model. Although important conceptually, these corrections give subleading contributions in current high energy experiments, and it was previously thought that they are difficult to detect. We also discuss the separate contribution of the Higgs boson.Comment: 9 pages (LaTeX + 3 PS figures, needs psfig

    Anatomical variations of the coeliac trunk in the homogeneous Polish population

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    Background: The abdominal vessels show a number of abnormalities and pathologies knowledge of which is important during open as well as laparoscopic surgeries. One of the most common vessels which pattern has many variations is the coeliac trunk. The present study was undertaken on homogeneous population to assess morphology of the coeliac trunk and to evaluate the possible variability of its branches. Materials and methods: Standard abdominal multidetector computed tomography examinations were performed on a total of 1569 patients diagnosed by 2 radiologists independently; in case of doubts common assessment was performed. Results: The coeliac trunk followed the classic pattern in 92.7% of the cases (1455/1569 of patients). The gastrosplenic trunk was detected in 4.1% of cases (64/1569); the hepatosplenic trunk in 2.2% of cases (34/1569); the coeliac-mesenteric trunk was observed in 0.5% of cases (8/1569); the hepatogastric trunk in 0.2% of cases (4/1569); the splenomesenteric trunk was detected in 0.1% of cases (2/1569). In the next 0.1% the coeliac trunk was absent. The hepatosplenomesenteric and the coeliac-colic trunk were not observed in the study population. Conclusions: Vascular anatomical abnormality is usually asymptomatic hovewer, its preoperative knowledge is helpful to reduce complications like vascular bleeding when dissecting the hapato-pancreatic region. The coeliac trunk and its branches can be fast and easy evaluated in computed tomography exams performed due to various symptoms from abdominal cavity

    Simulation techniques in the anatomy curriculum: review of literature

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    Modern medical education faces a problem of combining the latest technology, procedures and information with classic teaching methods. Simulation is a technique, which replaces or amplifies doctor–patient experiences in controlled conditions and therefore evokes or replicates substantial aspects of the real world in a fully interactive manner. The basic course of anatomy in medical education could be recognised as the best example of implementing new educational techniques such as simulation, into the traditional medical curriculum. The PubMed database was searched using specific key words. Finally 72 articles were accepted and were divided into 3 basic categories of teaching methods: Category 1 — cadaveric dissection, Category 2 — simulator based education and Category 3 — other. A state of the art anatomical curriculum offers numerous possibilities and solutions including the oldest like cadaveric dissection and newest like simulators. Different simulation techniques are used with different intensity; however cadaveric dissection is still the most popular method. The second most frequent method is simulation-based training, in which North America is the leading country. The identification of anatomical structures during virtual surgical procedures or laparoscopic robotic procedures can be integrated into the traditional anatomy course. New technologies are supportive and beneficial in anatomy teaching however each excitement of new technologies sometimes should be tempered and evaluated for its usefulness in making the learning process constructive for students and their future practice

    Review of the Properties of the W Boson at LEP, and the Precision Determination of its Mass

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    We review the precision measurement of the mass and couplings of the W Boson at LEP. The total and differential W+W- cross section is used to extract the WWZ and WWgamma couplings. We discuss the techniques used by the four LEP experiments to determine the W mass in different decay channels, and present the details of methods used to evaluate the sources of systematic uncertainty.Comment: 97 page

    Event Generators for Bhabha Scattering

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    The results obtained by the "Event Generators for Bhabha Scattering" working group during the CERN Workshop "Physics at LEP2" (1994/1995) are presented.Comment: 70 pages, PostScript file. To appear in the Report of the Workshop on Physics at LEP2, G. Altarelli T. Sjostrand and F. Zwirner ed

    Two-Fermion Production in Electron-Positron Collisions

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    This report summarizes the results of the two-fermion working group of the LEP2-MC workshop, held at CERN from 1999 to 2000. Recent developments in the theoretical calculations of the two fermion production process in the electron-positron collision at LEP2 center of the mass energies are reported. The Bhabha process and the production of muon, tau, neutrino and quark pairs is covered. On the basis of comparison of various calculations, theoretical uncertainties are estimated and compared with those needed for the final LEP2 data analysis. The subjects for the further studies are identified.Comment: 2-fermion working group report of the LEP2 Monte Carlo Workshop 1999/2000, 113 pages, 24 figures, 35 table

    Mammotome HH biopsy : the future of minimal invasive breast surgery?

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    Background: Vacuum-assisted breast biopsy / Mammotome HH Âź Breast Biopsy System/ is the milestone in the diagnosis of breast lesions. This system has proven to be as diagnostically reliable as open surgery, but without scarring, deformations and hospitalizations associated with an open procedure. The aim of our study was to assess the role and possibilities of using this biopsy in treatment of benign breast lesions like fibroadenoma. Material/Methods: From 2001 to 2004, about 1118 Mammotome biopsies were performed in our Department. Among 445 Mammotome biopsies performed under US control there were 211 cases of fibroadenomas. Follow-up was performed in 156 patients with this result at 6 and 12 months after biopsy. In our study we took into considerations the size, localizations as well as performers. Results: In 2002 there were 70.8% patients with total lesion excision, 16.7% with residual lesion and 12.5% women with hematomas or scars. In 2003-2004 there were more women with total lesion excision (84.3%), fewer residual tumors and other lesions. Conclusions: In future, Mammotome breast biopsy can replace scalpel, and will become an alternative method to open surgical excision of fibroadenomas. It is important especially in the cases of young women to prevent cosmetic deformations and scars
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