Double Q2Q^2-rescaling model and the nuclear effect of the parton distribution functions

In order to overcome the shortcoming of nonconservation of nuclear momentum existing in the original $Q^2$-rescaling model(O$Q^2$RM) and avoid introducing nuclear shadowing factor, we proposed a double $Q^2$-rescaling model(D$Q^2$RM) for the parton distributions of the bound nucleon. Using the experimental data of lepton-nucleus deep inelastic scattering(DIS) and the condition of the nuclear momentum conservation, the $Q^2$-rescaling parameters of various partons for Sn, Fe, Ca and C nuclei are determined. The rescaling parameters of valence quark distributions are larger than unity and graduauly increases with atomic number A, on the contrary, the rescaling parameters of sea quark distributions and gluon distributions are smaller than unity, and slowly decreases with A. By using this model, the experimental data of the DIS process, the nuclear Drell-Yan process and $J/\psi$ photoproduction process are consistently and quite satisfactorily explained. Key words --- parton distribution functions, Nuclear effect, Double $Q^2$-rescaling model.Comment: 15 pages, 4 figures (to be published in Z. Phys. C

Clinical outcomes of prophylactic Damus-Kaye-Stansel anastomosis concomitant with bidirectional Glenn procedure

ObjectiveWe evaluated prophylactic Damus-Kaye-Stansel (DKS) anastomosis in association with the timing of a bidirectional Glenn (BDG) procedure as second-stage palliation aiming at Fontan completion to prevent late systemic ventricular outflow tract obstruction.MethodsBetween 1996 and 2005, 25 patients (14 boys; median age, 12 months) underwent a BDG procedure concomitant with DKS anastomosis. All had a systemic ventricular outflow tract through an intraventricular communication or morphologically developed subaortic conus and had previously undergone pulmonary artery banding. Enlargement of intraventricular communication and/or resection of a subaortic conus were not performed before or during the operation.ResultsTwenty-one (84%) patients subsequently underwent a Fontan operation, with a follow-up period of 6.8 ± 1.9 years (range, 4-11 years), with no mortalities after the Fontan operation. Cardiac catheterization showed that systemic ventricular end-diastolic volume was significantly decreased from 187% ± 74% of normal before BDG to 139% ± 35% after (P = .038) and to 73% ± 14% at 4.3 years after the Fontan operation (P < .001). However, the pressure gradient across the systemic ventricular outflow tract remained at 0.5 ± 0.8 mm Hg after DKS anastomosis and 0.6 ± 2.3 mm Hg at 4.6 years after the Fontan operation. None of the patients showed more than moderate aortic or neoaortic regurgitation, except 1 who progressed to pulmonary regurgitation after DKS anastomosis and required a reoperation for a systemic ventricular outflow tract. No anatomic properties affected late neoaortic valve function.ConclusionsRegardless of a significant reduction in systemic ventricular volume, DKS anastomosis concomitant with a BDG procedure shows promise for a nonobstructive systemic ventricular outflow tract after a Fontan operation

Long-term outcomes after definitive repair for tetralogy of Fallot with preservation of the pulmonary valve annulus

ObjectivesThe aim of our study was to evaluate the long-term outcomes after definitive repair of tetralogy of Fallot with preservation of the pulmonary valve (PV) annulus.MethodsFrom 1989 to 2000, 84 of 222 patients (37.8%) with tetralogy of Fallot and PV stenosis underwent definitive repair with preservation of the PV annulus without right ventriculotomy. PV commissurotomy was concomitantly performed in 74 patients (88.1%). The PV was bicuspid in 56 patients (66.7%); the mean Z value was −1.2 ± 1.5 (range, −4.9 to 2.4). The mean follow-up period was 15.8 ± 5.7 years (maximum, 22.8), and follow-up data were complete for 75 patients (89.3%).ResultsThe actuarial survival and freedom from reoperation rates at 20 years was 98.6% and 95.8%. The freedom from ventricular arrhythmia at 5, 10, 15, and 20 years was 98.7%, 89.6%, 74.1%, and 58.0%, respectively. All detected ventricular arrhythmias were isolated monofocal premature ventricular contractions. Freedom from moderate or greater pulmonary regurgitation at 5, 10, 15 and 20 years was 50.4%, 44.9%, 38.4%, and 35.7%, respectively. A bicuspid PV (hazard ratio, 2.910; 95% confidence interval, 1.404-6.204, P = .004) and a Z-value of less than −2 (hazard ratio, 1.948; 95% confidence interval, 0.915-5.857; P = .034) were the risk factors for developing moderate or greater pulmonary regurgitation.ConclusionsThe long-term outcomes after definitive repair of tetralogy of Fallot with preservation of the PV annulus were excellent. Although isolated, monofocal premature ventricular contractions were frequently observed, fatal ventricular arrhythmia was not. The indication should not only be decided by the PV annulus size, but also by the valvular morphology to maintain long-term PV competency