We report on a measurement of the parity violating asymmetry in the elastic scattering of polarized electrons off unpolarized protons with the A4 apparatus at MAMI in Mainz at a four momentum transfer value of Q 2 = 0.108 (GeV/c) 2 and at a forward electron scattering angle of 30 • < θe < 40 • . The measured asymmetry is ALR( ep) = (-1.36 ± 0.29stat ± 0.13syst) × 10 −6 . The expectation from the Standard Model assuming no strangeness contribution to the vector current is A0 = (-2.06± 0.14) × 10 −6 . We have improved the statistical accuracy by a factor of 3 as compared to our previous measurements at a higher Q 2 . We have extracted the strangeness contribution to the electromagnetic form factors from our data to be G s E + 0.106 G s M = 0.071 ± 0.036 at Q 2 = 0.108 (GeV/c) 2 . As in our previous measurement at higher momentum transfer for G s E + 0.230 G s M , we again find the value for G s E + 0.106 G s M to be positive, this time at an improved significance level of 2 σ.

Abstract*Correspondence, page proofs, and reprint requests to: James D. Tucker, Ph.D., Department of Biological Sciences, 1370 Biological Sciences Building, 5047 Gullen Mall, Wayne State University, Detroit, TEL: (313) 577-2783, FAX: (313) 577-3602, EMAIL: E-mail: jtucker@biology.biosci.wayne.edu. z Retired Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Chromosome translocations in peripheral blood lymphocytes of normal, healthy humans increase with age, but the effects of gender, race, and cigarette smoking on background translocation yields have not been examined systematically. Further, the shape of the relationship between age and translocation frequency (TF) has not been definitively determined. We collected existing data from sixteen laboratories in North America, Europe, and Asia on TFs measured in peripheral blood lymphocytes by fluorescence in situ hybridization whole chromosome painting among 1933 individuals. In Poisson regression models, age, ranging from newborns (cord blood) to 85 years, was strongly associated with TF and this relationship showed significant upward curvature at older ages vs. a linear relationship (p <0.001). Ever smokers had significantly higher TFs than non-smokers (rate ratio (RR) = 1.19, 95% confidence interval (CI), 1.09-1.30) and smoking modified the effect of age on TFs with a steeper age-related increase among ever smokers compared to non-smokers (p<0.001). TFs did not differ by gender. Interpreting an independent effect of race was difficult owing to laboratory variation. Our study is three times larger than any pooled effort to date, confirming a suspected curvilinear relationship of TF with age. The significant effect of cigarette smoking has not been observed with previous pooled studies of TF in humans. Our data provide stable estimates of background TF by age, gender, race, and smoking status and suggest an acceleration of chromosome damage above age 60 and among those with a history of smoking cigarettes. NIH Public Access

We report on a measurement of the asymmetry in the scattering of transversely polarized electrons off unpolarized protons, A ⊥ , at two Q 2 values of 0.106 (GeV/c) 2 and 0.230 (GeV/c) 2 and a scattering angle of 30−6 . The first errors denotes the statistical error and the second the systematic uncertainties. A ⊥ arises from the imaginary part of the two-photon exchange amplitude and is zero in the one-photon exchange approximation. From comparison with theoretical estimates of A ⊥ we conclude that πN-intermediate states give a substantial contribution to the imaginary part of the two-photon amplitude. The contribution from the ground state proton to the imaginary part of the two-photon exchange can be neglected. There is no obvious reason why this should be different for the real part of the two-photon amplitude, which enters into the radiative corrections for the Rosenbluth separation measurements of the electric form factor of the proton.

We report on a measurement of the parity-violating asymmetry in the scattering of longitudinally polarized electrons on unpolarized protons at a Q2 of 0.230 (GeV/c)(2) and a scattering angle of theta (e) = 30 degrees - 40 degrees. Using a large acceptance fast PbF2 calorimeter with a solid angle of delta omega = 0.62 sr, the A4 experiment is the first parity violation experiment to count individual scattering events. The measured asymmetry is A(phys)=(-5.44+/-0.54(stat)+/-0.26(sys))x10(-6). The standard model expectation assuming no strangeness contributions to the vector form factors is A(0) = (-6.30+/-0.43) x 10(-6). The difference is a direct measurement of the strangeness contribution to the vector form factors of the proton. The extracted value is G(s)(E) + 0.225G(s)(M) = 0.039+/-0.034 or F(s)(1) + 0.130F(s)(2) = 0.032+/-0.028.

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