51 research outputs found

    Virtual Compton Scattering and Neutral Pion Electroproduction in the Resonance Region up to the Deep Inelastic Region at Backward Angles

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    We have made the first measurements of the virtual Compton scattering (VCS) process via the H(e,eâ€Čp)Îł(e,e'p)\gamma exclusive reaction in the nucleon resonance region, at backward angles. Results are presented for the WW-dependence at fixed Q2=1Q^2=1 GeV2^2, and for the Q2Q^2-dependence at fixed WW near 1.5 GeV. The VCS data show resonant structures in the first and second resonance regions. The observed Q2Q^2-dependence is smooth. The measured ratio of H(e,eâ€Čp)Îł(e,e'p)\gamma to H(e,eâ€Čp)π0(e,e'p)\pi^0 cross sections emphasizes the different sensitivity of these two reactions to the various nucleon resonances. Finally, when compared to Real Compton Scattering (RCS) at high energy and large angles, our VCS data at the highest WW (1.8-1.9 GeV) show a striking Q2Q^2- independence, which may suggest a transition to a perturbative scattering mechanism at the quark level.Comment: 20 pages, 8 figures. To appear in Phys.Rev.

    Precision measurement of the deuteron spin structure function g1dg^{d}_{1}

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    We report on a high-statistics measurement of the deuteron spin structure function g[sup d][sub 1] at a beam energy of 29 GeV in the kinematic range 0.029 < x < 0.8 and 1 < Q2 < 10 (GeV/c)2. The integral Gamma [sup d][sub 1] = (integral)[sup 1][sub 0]g[sup d][sub 1]dx evaluated at fixed Q2 = 3 (GeV/c)2 gives 0.042 ± 0.003(stat) ± 0.004(syst). Combining this result with our earlier measurement of g[sup p][sub 1], we find Gamma [sup p][sub 1]- Gamma [sup n][sub 1] = 0.163 ± 0.010(stat) ± 0.016(syst), which agrees with the prediction of the Bjorken sum rule with O( alpha [sup 3][sub s]) corrections, Gamma [sup p][sub 1]- Gamma [sup n][sub 1] = 0.171 ± 0.008. We find the quark contribution to the proton helicity to be Delta q = 0.30 ± 0.06

    Dynamics of the 16^{16}O(e,e'p) cross section at high missing energies

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    We measured the cross section and response functions (R_L, R_T, and R_LT) for the 16O(e,e'p) reaction in quasielastic kinematics for missing energies 25 60 MeV and P_miss > 200 MeV/c, the cross section is relatively constant. Calculations which include contributions from pion exchange currents, isobar currents and short-range correlations account for the shape and the transversity but only for half of the magnitude of the measured cross section

    Updated Nucleosynthesis Constraints on Unstable Relic Particles

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    We revisit the upper limits on the abundance of unstable massive relic particles provided by the success of Big-Bang Nucleosynthesis calculations. We use the cosmic microwave background data to constrain the baryon-to-photon ratio, and incorporate an extensively updated compilation of cross sections into a new calculation of the network of reactions induced by electromagnetic showers that create and destroy the light elements deuterium, he3, he4, li6 and li7. We derive analytic approximations that complement and check the full numerical calculations. Considerations of the abundances of he4 and li6 exclude exceptional regions of parameter space that would otherwise have been permitted by deuterium alone. We illustrate our results by applying them to massive gravitinos. If they weigh ~100 GeV, their primordial abundance should have been below about 10^{-13} of the total entropy. This would imply an upper limit on the reheating temperature of a few times 10^7 GeV, which could be a potential difficulty for some models of inflation. We discuss possible ways of evading this problem.Comment: 40 pages LaTeX, 18 eps figure

    Analysis of the 16p telomere to examine the relationship between DNA replication, chromosome structure and gene expression

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    SIGLEAvailable from British Library Document Supply Centre-DSC:D201312 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

    A multi centre prospective longitudinal study evaluating health related quality of life after immediate Latissimus dorsi (LD) breast reconstruction

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    Introduction: NICE recommends that the majority of women should be offered immediate breast reconstruction with its potential to improve health related quality of life (HRQL). There is conflicting evidence with a lack of ‘hard’data to best inform clinicians and their patients. Our aim was to evaluate the effects of implant-assisted LD (LDI) versus autologous LD (ALD) breast reconstruction on HRQL over 12 months. Methods: A prospective longitudinal multicentre study commenced in early 2007. Patient reported outcome measures using the EORTC C30 (general HRQL), BR-23 (breast + arm symptoms), Body Image Scale (BIS) and HADS, were completed pre-operatively and at 3, and 12 months after surgery. Longitudinal analyses tested the effects of treatment variables, baseline HRQL, age and time on QL domains (3–12 months). Significance was set at p = 0.01. Results: One hundred and seventy one patients (93 ALD, 78 LDI) were recruited. There were no significant differences in HRQL domains between LDI and ALD (±RT). Chemotherapy patients reported poorer overall HRQL (p &lt; 0.001), poorer role (p = 0.003) and social (p = 0.01) functioning, and greater fatigue (p = 0.002) and depression (p = 0.01). Older patients had fewer HRQL issues (p = 0.01). Significant improvements over time were seen for overall HRQL and other domains (p &lt; 0.001). There were no significant differences between LDI and ALD for patient satisfaction with surgical outcome. Good satisfaction with overall breast appearance and surgical outcome was significantly associated with fewer body image concerns. Conclusion: There is an important need for cumulative clinical evidence in this field on which to base patient informed consent and clinical recommendations
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