Determination of αs\alpha_s and the Nucleon Spin Decomposition Using Recent Polarized Structure Function Data

New data on polarized $\mu-p$ and $e-p$ scattering permit a first determination of $\alpha_s$ using the Bjorken sum rule, as well as higher precision in determining the nucleon spin decomposition. Using perturbative QCD calculations to $O(\alpha_s^4)$ for the non-singlet combination of structure functions, we find $\alpha_s(2.5 GeV^2) = 0.375^{+0.062}_{-0.081}$, corresponding to $\alpha_s(M_Z^2) =0.122^{+0.005}_{-0.009}$, and using calculations to $O(\alpha_s^3)$ for the singlet combination we find $\Delta u = 0.83 \pm 0.03$, $\Delta d= -0.43 \pm 0.03$, $\Delta s =-0.10 \pm 0.03$, \Delta \Sigma \equiv \Delta u + \Delta d + \Ds = 0.31 \pm 0.07, at a renormalization scale $Q^2=10 GeV^2$. Perturbative QCD corrections play an essential role in reconciling the interpretations of data taken using different targets. We discuss higher-twist uncertainties in these determinations. The $\Delta q$ determinations are used to update predictions for the couplings of massive Cold Dark Matter particles and axions to nucleons.Comment: 15 pages (LateX) + 5 postscript figures appended after the text; CERN-TH-7324/94, TAUP-2178-9

Impact of Weight Loss Due to Sleeve Gastrectomy on Shear Stress of the Femoral Vein in Morbid Obesity

BACKGROUND: Studies have shown that obesity is associated with venous flow disturbances that lead to changes of the biomechanical forces on the venous wall known as shear stress. We hypothesized that weight loss due to bariatric surgery affects the venous hemodynamics and biomechanical forces on the venous wall. The aim of this study was to evaluate the effects of laparoscopic sleeve gastrectomy (LSG) on the wall shear stress (WSS) and the venous hemodynamics of the femoral vein. METHODS: We studied ten morbidly obese patients who underwent LSG. We investigated venous hemodynamics before, 6 and 12 months after LSG. The femoral vein diameter, cross-sectional area, peak (PeakV) and maximum (TA(max)) velocities, WSS, and shear rate (SR) were assessed. RESULTS: PeakV and TA(max) were significantly lower in the obese patients compared with the control group. WSS and SR were significantly lower in the obese patients compared with the control subjects. Venous hemodynamic parameters increased in the postoperative period at baseline compared with 12 months after surgery: PeakV increased from 17.53 (14.25–20.01) cm/s to 25.1 (20.9–30.1) cm/s (P = 0.04) and the TA(max) from 12.97 (11.51–14.6) cm/s to 18.46 (13.24–24.13) cm/s (P = 0.057). WSS significantly increased from 0.21 (0.19–0.23) Pa at baseline to 0.31 (0.23–0.52) Pa 12 months after surgery (P = 0.031). SR also significantly increased from 47.92 (43.93–58.55) s(−1) at baseline to 76.81 (54.04–109.5) s(−1) 12 months after surgery (P = 0.02). CONCLUSIONS: This study showed that weight loss due to LSG significantly changes the biomechanical forces on the femoral vein generated by blood flow