32 research outputs found

    Measurement of the proton electric to magnetic form factor ratio from \vec ^1H(\vec e, e'p)

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    We report the first precision measurement of the proton electric to magnetic form factor ratio from spin-dependent elastic scattering of longitudinally polarized electrons from a polarized hydrogen internal gas target. The measurement was performed at the MIT-Bates South Hall Ring over a range of four-momentum transfer squared Q2Q^2 from 0.15 to 0.65 (GeV/c)2^2. Significantly improved results on the proton electric and magnetic form factors are obtained in combination with previous cross-section data on elastic electron-proton scattering in the same Q2Q^2 region.Comment: 4 pages, 2 figures, submitted to PR

    Observation of Parity Nonconservation in Moller Scattering

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    We report a measurement of the parity-violating asymmetry in fixed target electron-electron (Moller) scattering: A_PV = -175 +/- 30 (stat.) +/- 20 (syst.) parts per billion. This first direct observation of parity nonconservation in Moller scattering leads to a measurement of the electron's weak charge at low energy Q^e_W = -0.053 +/- 0.011. This is consistent with the Standard Model expectation at the current level of precision: sin^2\theta_W(M_Z)_MSbar = 0.2293 +/- 0.0024 (stat.) +/- 0.0016 (syst.) +/- 0.0006 (theory).Comment: Version 3 is the same as version 2. These versions contain minor text changes from referee comments and a change in the extracted value of Q^e_W and sin^2\theta_W due to a change in the theoretical calculation of the bremsstrahulung correction (ref. 16

    New Measurement of Parity Violation in Elastic Electron-Proton Scattering and Implications for Strange Form Factors

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    We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton. The result is A = -15.05 +- 0.98(stat) +- 0.56(syst) ppm at the kinematic point theta_lab = 12.3 degrees and Q^2 = 0.477 (GeV/c)^2. The measurement implies that the value for the strange form factor (G_E^s + 0.392 G_M^s) = 0.025 +- 0.020 +- 0.014, where the first error is experimental and the second arises from the uncertainties in electromagnetic form factors. This measurement is the first fixed-target parity violation experiment that used either a `strained' GaAs photocathode to produce highly polarized electrons or a Compton polarimeter to continuously monitor the electron beam polarization.Comment: 8 pages, 4 figures, Tex, elsart.cls; revised version as accepted for Phys. Lett.

    Rotavirus group : a genotype circulation patterns across Kenya before and after nationwide vaccine introduction, 2010-2018

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    Background Kenya introduced the monovalent G1P [8] Rotarix® vaccine into the infant immunization schedule in July 2014. We examined trends in rotavirus group A (RVA) genotype distribution pre- (January 2010–June 2014) and post- (July 2014–December 2018) RVA vaccine introduction. Methods Stool samples were collected from children aged < 13 years from four surveillance sites across Kenya: Kilifi County Hospital, Tabitha Clinic Nairobi, Lwak Mission Hospital, and Siaya County Referral Hospital (children aged < 5 years only). Samples were screened for RVA using enzyme linked immunosorbent assay (ELISA) and VP7 and VP4 genes sequenced to infer genotypes. Results We genotyped 614 samples in pre-vaccine and 261 in post-vaccine introduction periods. During the pre-vaccine introduction period, the most frequent RVA genotypes were G1P [8] (45.8%), G8P [4] (15.8%), G9P [8] (13.2%), G2P [4] (7.0%) and G3P [6] (3.1%). In the post-vaccine introduction period, the most frequent genotypes were G1P [8] (52.1%), G2P [4] (20.7%) and G3P [8] (16.1%). Predominant genotypes varied by year and site in both pre and post-vaccine periods. Temporal genotype patterns showed an increase in prevalence of vaccine heterotypic genotypes, such as the commonly DS-1-like G2P [4] (7.0 to 20.7%, P < .001) and G3P [8] (1.3 to 16.1%, P < .001) genotypes in the post-vaccine introduction period. Additionally, we observed a decline in prevalence of genotypes G8P [4] (15.8 to 0.4%, P < .001) and G9P [8] (13.2 to 5.4%, P < .001) in the post-vaccine introduction period. Phylogenetic analysis of genotype G1P [8], revealed circulation of strains of lineages G1-I, G1-II and P [8]-1, P [8]-III and P [8]-IV. Considerable genetic diversity was observed between the pre and post-vaccine strains, evidenced by distinct clusters. Conclusion Genotype prevalence varied from before to after vaccine introduction. Such observations emphasize the need for long-term surveillance to monitor vaccine impact. These changes may represent natural secular variation or possible immuno-epidemiological changes arising from the introduction of the vaccine. Full genome sequencing could provide insights into post-vaccine evolutionary pressures and antigenic diversity

    Physiological parameters for Prognosis in Abdominal Sepsis (PIPAS) Study : a WSES observational study

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    BackgroundTiming and adequacy of peritoneal source control are the most important pillars in the management of patients with acute peritonitis. Therefore, early prognostic evaluation of acute peritonitis is paramount to assess the severity and establish a prompt and appropriate treatment. The objectives of this study were to identify clinical and laboratory predictors for in-hospital mortality in patients with acute peritonitis and to develop a warning score system, based on easily recognizable and assessable variables, globally accepted.MethodsThis worldwide multicentre observational study included 153 surgical departments across 56 countries over a 4-month study period between February 1, 2018, and May 31, 2018.ResultsA total of 3137 patients were included, with 1815 (57.9%) men and 1322 (42.1%) women, with a median age of 47years (interquartile range [IQR] 28-66). The overall in-hospital mortality rate was 8.9%, with a median length of stay of 6days (IQR 4-10). Using multivariable logistic regression, independent variables associated with in-hospital mortality were identified: age > 80years, malignancy, severe cardiovascular disease, severe chronic kidney disease, respiratory rate >= 22 breaths/min, systolic blood pressure 4mmol/l. These variables were used to create the PIPAS Severity Score, a bedside early warning score for patients with acute peritonitis. The overall mortality was 2.9% for patients who had scores of 0-1, 22.7% for those who had scores of 2-3, 46.8% for those who had scores of 4-5, and 86.7% for those who have scores of 7-8.ConclusionsThe simple PIPAS Severity Score can be used on a global level and can help clinicians to identify patients at high risk for treatment failure and mortality.Peer reviewe

    Effects of temperature on the germination of Fraxinus ornus subsp. cilicica seeds

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    The present study was carried out to determine the effect of temperature on the seed germination of Fraxinus ornus subsp. cilicica, an endemic taxa on Taurus Mountains in Southern Turkey. Seeds from the three provenances were collected and prechilled for 16 weeks before the germination tests. Germination tests were conducted at constant temperatures (5, 15, 20, 25°C) and at alternating temperatures (5~15, 5~20, 5~25, 15~25°C). Temperature treatments were effective on germination percentage and mean germination time. The highest and the lowest germinability were obtained at the 5–15°C (73.3%) alternating and 25°C (9.8%) constant temperatures, respectively. Mean germination time greatly differed at various temperature regimes. Germination accelerated with increased constant temperatures while it was relatively similar speed at alternating temperatures used in the tests. Seed sources had also an effect on the final germination percentage

    The management of renal candidiasis in the newborn

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    Renal candidiasis in the neonate is encountered Infrequently. We report a newborn with ichthyosis, who during the hospital course had five episodes of culture-proven sepsis, probably due to skin lesions. For these infections various antibiotic combinations were used. During the therapy of the last sepsis attack, unilateral hydronephrosis developed secondary to renal candidiasis. Percutaneous nephrostomy with amphotericin B irrigation, coupled with five weeks of intravenous amphotericin B therapy was successful. We believe that with this approach the mortality and morbidity of renal candidiasis could be reduced

    Endovascular treatment of arteriovenous fistulas complicating percutaneous renal biopsy in three paediatric cases

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    Design. We evaluated the incidence and history of arteriovenous fistula (AVF) after kidney biopsy and assessed the use of superselective embolization for treatment
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