On Strong convergence of Halpern's method using averaged type mappings

In this paper, inspired by Iemoto and Takahashi [S. Iemoto, W. Takahashi, Nonlinear Analysis 71, (2009), 2082-2089], we study the Halpern's method to approximate strongly fixed points of a nonexpansive mapping and of a nonspreading mapping. A crucial tool in our results is the regularization with the averaged type mappings [C. Byrne, Inverse Probl. 20, (2004), 103-120]

Body composition and cardiovascular risk factors in pretransplant hemodialysis patients

BACKGROUND: Obesity, hyperlipemia and cardiovascular complications contribute to a significant proportion of morbidity and mortality of renal transplant patients and have negative effects on renal survival. Aim of the present study was to evaluate the main abnormalities in body composition and the prevalence of some cardiovascular risk factors in a population of hemodialyzed (HD) patients awaiting renal transplantation. METHODS: We studied 151 HD patients, all included in a waiting list for renal transplantation, 97 males and 54 females, with mean age 47.4+/-12 years. Patients were divided into three groups according to their body mass index (BMI) (kg/m2): 18.5 to 24.9 (normoweight, NW); 25.0 to 29.9 (overweight, OW); > or =30 (obese, OB). The body composition measurements were obtained the day after the mid-week HD session using bioelectrical impedance analysis (BIA). RESULTS: We found that 47 patients were NW (31%), while 56 were OW (37%), and 48 were OB (32%). BIA-measured body cell mass was (BCM) significantly increased in the OW as compared with the NW group (P<0.001), but, of note, no significant difference was found in OB group in comparison with the OW. Total cholesterol and triglycerides plasma levels were significantly elevated in OW and OB patients with respect to NW (P<0.05) and an increased prevalence of diabetes was seen in OB patients (NW: 6%, OW: 5%, OB: 12%). CONCLUSIONS: These data show that a large proportion of patients awaiting renal transplant are overweight or obese and a consistent part of them have other cardiovascular risk factors associated. Furthermore, obese HD patients have a BCM lower than predicted on the basis of BMI and show an altered metabolic profile. A better understanding of the characteristics of patients included in the renal transplant waiting list is crucial in order to design prospective studies that aim to define the proper risk profile for the selection of patients

Fixed Point Iterations for Nonlinear Mappings

Dottorato di Ricerca in Matematica ed Informatica, Ciclo XXVIII a.a. 2015-2016In questa tesi vengono a rontati, e talvolta risolti, alcuni problemi sulla convergenza di algoritmi per punti ssi. A tali problemi, verr a a ancato inoltre l'ulteriore problema di stabilire quando tali algoritmi convergono a punti ssi che risultano essere soluzioni di disuguaglianze variazionali. I contributi scienti ci personali apportati alla teoria dei punti ssi, riguardano essenzialmente la ricerca di ottenere convergenza forte di uno o pi u metodi iterativi, laddove non e nota convergenza, o qualora e nota la sola convergenza debole. La struttura dei capitoli e articolata come segue: Nel primo capitolo vengono introdotti gli strumenti di base e i cosiddetti spazi ambiente in cui verranno mostrati i principali risultati. Inoltre verranno fornite tutte le propriet a sulle mappe nonlineari utili nelle dimostrazioni presenti nei capitoli successivi. Nel secondo capitolo, e presente una breve e mirata introduzione a quelli che sono alcuni dei risultati fondamentali sui metodi iterativi di punto sso pi u noti in lettaratura. Nel terzo capitolo, vengono mostrate le principali applicazioni dei metodi di approssi- mazione di punto sso. Nel quarto e nel quinto capitolo, vengono mostrati nei dettagli alcuni risultati riguardo un metodo iterativo di tipo Mann e il metodo iterativo di Halpern. In questi ultimi capitoli sono presenti i contributi dati alla teoria dell'approssimazione di punti ssi.Università della Calabri