Finite-size scaling studies of reaction-diffusion systems. Pt. 1 Periodic boundary conditions

The finite-size scaling function and the leading corrections for the single species 1D coagulation model (A + A #-># A) and the annihilation model (A + A #-># 0) are calculated. The scaling functions are universal and independent of the initial conditions but do depend on the boundary conditions. A similarity transformation between the two models is derived and used to connect the corresponding scaling functions. (orig.)Available from TIB Hannover: RN 5063(93-51) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Finite-size scaling studies of reaction-diffusion systems. Pt. 3 Numerical methods

The scaling exponent and scaling function for the 1D single species coagulation model (A + A #-># A) are shown to be universal, i.e. they are not influenced by the value of the coagulation rate. They are independent of the initial conditions as well. Two different numerical methods are used to compute the scaling properties: Monte Carlo simulations and extrapolations of exact finite lattice data. These methods are tested in a case where analytical results are available. It is shown that Monte Carlo simulations can be used to compute even the correction terms. To obtain reliable results from finite-size extrapolations exact numerical data for lattices up to ten sites are sufficient. (orig.)Available from TIB Hannover: RN 5063(94-02) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Finite-size scaling studies of reaction-diffusion systems. Pt. 2 Open boundary conditions

We consider the coagulation-decoagulation model on an one-dimensional lattice of length L with open boundary conditions. Based on the empty interval approach the time evolution is described by a system of L(L+1)/2 differential equations which is solved analytically. An exact expression for the concentration is derived and its finite-size scaling behaviour is investigated. The scaling function is found to be independent of initial conditions. The scaling function and the correction function for open boundary conditions are different from those for periodic boundary conditions. (orig.)Available from TIB Hannover: RN 5063(94-01) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Surgery for infective endocarditis complicated by cerebral embolism: a consecutive series of 375 patients

ObjectiveTo determine the influence of silent and symptomatic cerebral embolism on outcome of urgent/emergent surgery after acute infective endocarditis (AIE).MethodsFrom a total of 1571 patients with AIE admitted to our institution between May 1995 and March 2012 about one-quarter (375 patients; mean age, 61.8 ± 13.6 years) presented with cerebral embolism confirmed by cranial computed tomography. Isolated aortic valve endocarditis was present in 165 patients (44%), 132 patients (36%) had isolated AIE of the mitral valve, and 64 (17%) patients had left-sided double valve endocarditis.ResultsAlthough the majority of patients presented with neurologic symptoms, 1 out of 3 patients experienced a so-called silent asymptomatic cerebral embolism or transient ischemic attack (n = 135). The rate of silent embolism was equivalent in patients with isolated aortic valve versus isolated mitral valve endocarditis (37% vs 34%; P = .54). Comparing patients with silent embolism versus symptomatic embolism, 18 patients with silent embolism versus 12 patients with symptomatic embolism developed postoperative hemiparesis (P = .69). Three versus 4 had severe postoperative intracerebral bleeding (P = .71). Median follow-up of survivors with cerebral embolism was 4.1 years (935 cumulative patient-years). Hospital mortality was 21.4% versus 19.6% (P = .68), with a long-term survival of 45% ± 5% versus 47% ± 4% at 5 years (P = .83) and 40% ± 6% versus 32% ± 5% at 10 years (P = .86). Independent risk factors of mortality were age at surgery (P < .01), chronic obstructive pulmonary disease (P = .01), preoperative requirement of catecholamines (P = .02), dialysis (P < .01), and duration of cardiopulmonary bypass (P < .01).ConclusionsSurvival after surgery for AIE is significantly impaired once cerebral embolism has occurred; however, it does not differ in patients with symptomatic versus silent cerebral embolism. Routine computed tomography scans are therefore mandatory due to the high incidence of asymptomatic cerebrovascular embolism—which appears to be equally as dangerous as symptomatic embolism