A Self-Consistent Model for Positronium Formation from Helium Atoms

The differential and total cross sections for electron capture by positrons from helium atoms are calculated using a first-order distorted wave theory satisfying the Coulomb boundary conditions. In this formalism a parametric potential is used to describe the electron screening in a consistent and realistic manner. The present procedure is self consistent because (i) it satisfies the correct boundary conditions and post-prior symmetry, and (ii) the potential and the electron binding energies appearing in the transition amplitude are consistent with the wave functions describing the collision system. The results are compared with the other theories and with the available experimental measurements. At the considered range of collision energies, the results agree reasonably well with recent experiments and theories. [Note: This paper will be published on volume 42 of the Brazilian Journal of Physics

Hypotension, acidosis and vasodilation syndrome after heart transplant: incidence, risk factors, and prognosis

[Abstract] Background. HAV syndrome, the combination of hypotension, acidosis and vasodilation (HAV), is a serious postoperative complication after heart transplantation (HT). Its etiology and prognosis are poorly understood. Aim. To determine the incidence and prognosis of post-HT HAV syndrome and examine possible risk factors. Methods. Retrospective examination of the records of 85 consecutive patients who underwent HT between December 1999 and June 2002 sought the HAV criteria: systolic BP <85 mm Hg plus HCO3 <19 mEq/l whole excluding cardiogenic, hypovolemic and septic shock. Donor variables included sex, age, weight, height, cause of death, time in ICU, and ischemic time; while recipient variables, sex, age, weight, height, etiology of cardiopathy, previous cardiopulmonary bypass surgery, preoperative amiodarone, β-blockers, catecholamines, mechanical ventilation or intra aortic balloon pump (IABP), RVP, time on waiting list, pump time, reoperations, polytransfusion, preoperative creatinine, GOT, GPT and GGT, induction with OKT3 or anti-CD25, bypass-to-HAV time, duration of catecholamine treatment, and 1 month survival after HT. Results. The 11 HAV cases (13%) appeared between 1 and 72 h after HT (75% in the first hour). Catecholamines were used for 1 to 6 days; control was achieved within 48 h in 58% of cases. Two HAV patients (18%) died within the first month versus six non-HAV patients (8.1%) (P = .275). Only polytransfusion showed more than a borderline value to predict HAV syndrome. Conclusions. HAV syndrome has an incidence of 13% and a mortality of 18% within 1 month post-HT. The only likely risk factor is polytransfusion

Axillary implantation of Impella CP allows early rehabilitation of patients in cardiogenic shock bridged to heart transplantation

Abstract poste

Theoretical ionization and capture cross sections for DNA nucleobases impacted by light ions

Although DNA lesions are considered of prime importance for describing the post-irradiation cellular survival, they still remain rarely studied on both experimental and theoretical sides. Under these conditions, we here propose different theoretical models for predicting the single ionization and single capture total cross sections for DNA bases impacted by protons

Proton-induced ionization of isolated uracil molecules: A theory/experiment confrontation

Proton-induced ionization of RNA-uracil target is here theoretically described by two quantum-mechanical models, namely, a first perturbative one developed within the 1st Born approximation and a second one based on the continuum distorted wave approximation. Comparisons between theory and experiments are reported in terms of differential as well as total cross sections exhibiting a very good agreement for the kinematics here investigated