44 research outputs found

    Population dynamics and economic development

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    This research develops a continuous-time optimal growth model that accounts for population dynamics resembling the historical pattern of the demographic transition. The Ramsey model then becomes able to generate multiple determinate or indeterminate stationary equilibria and explain the process of the transition from a state with high fertility and low income per capita to a state with low fertility and high income per capita. The article also investigates the emergence of damped or persistent cyclical dynamics

    Silver Makes Better Electrical Contacts to Thiol-Terminated Silanes than Gold

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    We report that the single-molecule junction conductance of thiol-terminated silanes with Ag electrodes are higher than the conductance of those formed with Au electrodes. These results are in contrast to the trends in the metal work function Phi(Ag)< Phi(Au). As such, a better alignment of the Au Fermi level to the molecular orbital of silane that mediates charge transport would be expected. This conductance trend is reversed when we replace the thiols with amines, highlighting the impact of metal-S covalent and metal-NH2 dative bonds in controlling the molecular conductance. Density functional theory calculations elucidate the crucial role of the chemical linkers in determining the level alignment when molecules are attached to different metal contacts. We also demonstrate that conductance of thiol-terminated silanes with Pt electrodes is lower than the ones formed with Au and Ag electrodes, again in contrast to the trends in the metal work-functions

    Clinical and Laboratory Features of 184 Italian Pediatric Patients Affected with Selective IgA Deficiency (SIgAD): a Longitudinal Single-Center Study

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    PURPOSE: Selective IgA deficiency (SIgAD) is the most common humoral primary immunodeficiency. Long-term follow-up data in large cohort of pediatric patients are scarce. METHODS: We report on a single-center cohort of 184 pediatric patients affected with selective IgA deficiency and describe the characteristics at diagnosis and during follow-up. RESULTS: Respiratory infections were the most common clinical finding leading to the initial diagnosis (62%). Positive family history for antibody deficiencies (selective IgA deficiency, common variable immunodeficiency) led to SIgAD diagnosis in 16% of cases. During follow-up, while the incidence of respiratory infections was not particularly high, gastrointestinal symptoms were reported in 27% of patients. Allergic manifestations were found in 23% at diagnosis and an additional 16% of patients during follow-up, leading to a prevalence of atopy of 39% among SIgAD patients. Autoimmune manifestations, excluding celiac disease, were found in 9% of affected patients during follow-up. Celiac disease was found in a high prevalence (14%). Increase of serum IgA levels to partial deficiency (9%) and normal serum levels for age (4%) was observed during follow-up. A small percentage of patients (2%) progressed to common variable immunodeficiency (CVID). CONCLUSIONS: In conclusion, this is the first study to describe a large single-center pediatric cohort of patients affected with SIgAD, revealing that overall most patients do well with regard to infections. Many develop CD, at a rate much higher than the general population. A few normalize their IgA levels. A few progress to CVID. Thus, careful follow-up is suggested to diagnose and treat potential complications earlier for avoiding potential morbidities
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