Prevalence, clinical features and risk assessment of pre-diabetes in Spain: the prospective Mollerussa cohort study

Purpose The Mollerussa prospective cohort was created to study pre-diabetes in a population-based sample from the primary care setting in the semirural area of Pla d'Urgell in Catalonia (Spain). The aims of the study were to assess the prevalence of pre-diabetes in our population, the likelihood to develop overt diabetes over time and to identify risk factors associated with the progression of the condition. Participants The cohort includes 594 subjects randomly selected between March 2011 and July 2014 from our primary care population, who were older than 25 years, consented to participate and did not have a recorded diagnosis of diabetes. Findings to date At baseline, we performed a clinical interview to collect demographic, clinical and lifestyle (including a nutritional survey) characteristics; carotid ultrasound imaging to assess subclinical cardiovascular disease was also performed, and a blood sample was collected, with an overall <5% rate of missing data. An additional blood draw was performed 12 months after initial recruitment to reassess laboratory results in patients initially identified as having pre-diabetes, with an 89.6% retention rate. Several studies investigating various hypotheses are currently ongoing. Future plans All subjects recruited during the cohort creation will be followed long-term through annual extraction of data from health records stored in the electronic Clinical station in Primary Care database. The Mollerussa cohort will thus be a sound population-based sample for multiple future research projects to generate insights into the epidemiology and natural history of pre-diabetes in Spain

Analysis of bias stress on thin-film transistors obtained by Hot-Wire Chemical Vapour Deposition

The stability under gate bias stress of unpassivated thin film transistors was studied by measuring the transfer and output characteristics at different temperatures. The active layer of these devices consisted of in nanocrystalline silicon deposited at 125°C by Hot-Wire Chemical Vapour Deposition. The dependence of the subthreshold activation energy on gate bias for different gate bias stresses is quite different from the one reported for hydrogenated amorphous silicon. This behaviour has been related to trapped charge in the active layer of the thin film transistor.Peer ReviewedPostprint (published version

Space charge recombination in p-n junctions with a discrete and continous trap distribution

Space charge Shockley-Read-Hall recombination currents in the presence of discrete or continuous distributions of recombination centres are analysed. For a single level trap, depending on its position inside the forbidden band, asymptotic values both for the ideality factor of the current-voltage characteristic and for the activation energy of the saturation current are obtained. The analysis is extended to continuous trap distributions and the current-voltage characteristics obtained are explained in terms of the simple theory developed for single level traps.Peer ReviewedPostprint (published version

Space charge recombination in p-n junctions with a discrete and continous trap distribution

Space charge Shockley-Read-Hall recombination currents in the presence of discrete or continuous distributions of recombination centres are analysed. For a single level trap, depending on its position inside the forbidden band, asymptotic values both for the ideality factor of the current-voltage characteristic and for the activation energy of the saturation current are obtained. The analysis is extended to continuous trap distributions and the current-voltage characteristics obtained are explained in terms of the simple theory developed for single level traps.Peer Reviewe

Distribution of recombination currents in the space charge of heterostructure bipolar devices

This paper addresses the problem of the space charge region Shockley-Read-Hall (SRH) recombination currents in heterojunctions with one noncrystalline side. A formulation which generalizes previous works is discussed. The approach is based on the drift-diffusion model with a thermionic-field emission boundary condition. The main physical parameters which determine the relative contribution of each zone of the space charge region (SCR) to the total recombination current are identified. The general analysis is applied for the first time to amorphous/crystalline heterojunctions and design criteria are established to minimize the total recombination current.Peer ReviewedPostprint (published version

Distribution of recombination currents in the space charge of heterostructure bipolar devices

This paper addresses the problem of the space charge region Shockley-Read-Hall (SRH) recombination currents in heterojunctions with one noncrystalline side. A formulation which generalizes previous works is discussed. The approach is based on the drift-diffusion model with a thermionic-field emission boundary condition. The main physical parameters which determine the relative contribution of each zone of the space charge region (SCR) to the total recombination current are identified. The general analysis is applied for the first time to amorphous/crystalline heterojunctions and design criteria are established to minimize the total recombination current.Peer Reviewe

Effects of symmetry reduction in two-dimensional square and triangular lattices

We investigate the absolute photonic band gap (PBG) formation in two-dimensional (2-D) photonic crystals designed using symmetry reduction approach. The lattice symmetry, shape and orientation of dielectric scatterers affect the photonic gap parameters. We use symmetry reduction, achieved either by including additional rods into the lattice unit cell or by reorienting noncircular scatterers to engineer the photonic band gaps in 2-D square and triangular structures. The case of air rods drilled into silicon background is considered. We show that for square structures symmetry reduction can be an effective way to enlarge the absolute PBG, but for triangular lattices any modification of the crystal structure considerably reduces the absolute PBG width. We also discuss the practical technological feasibility of the proposed structures.Peer ReviewedPostprint (published version

Analysis of photonic band gaps in two-dimensional photonic crystals with rods covered by a thin interfacial layer

We investigate different aspects of the absolute photonic band gap (PBG) formation in two-dimensional photonic structures consisting of rods covered with a thin dielectric film. Specifically, triangular and honeycomb lattices in both complementary arrangements, i.e., air rods drilled in silicon matrix and silicon rods in air, are studied. We consider that the rods are formed of a dielectric core (silicon or air) surrounded by a cladding layer of silicon dioxide (SiO2), silicon nitride (Si3N4), or germanium (Ge). Such photonic lattices present absolute photonic band gaps, and we study the evolution of these gaps as functions of the cladding material and thickness. Our results show that in the case of air rods in dielectric media the existence of dielectric cladding reduces the absolute gap width and may cause complete closure of the gap if thick layers are considered. For the case of dielectric rods in air, however, the existence of a cladding layer can be advantageous and larger absolute PBG’s can be achieved.Peer ReviewedPostprint (published version

Fabrication of two- and three-dimensional photonic crystals by electrochemical etching of silicon

This paper reports on the fabrication of two-dimensional macropore arrays by electrochemical etching of silicon. We describe some critical effects accompanying the etching process that can generate imperfections in the etched pore pattern. We also give the solutions to improve the pore uniformity and to produce high-aspect-ratio macropores with good structural characteristics. The obtained macroporous structures can be further processed to produce high-aspect-ratio pillars, instead of pores. By modulating the applied etching current we have also induced periodicity in the third dimension.Peer ReviewedPostprint (published version

In-situ doped amorphous Si0.8C0.2 emitter bipolar transistors

The fabrication and characterization of in situ-doped amorphous Si/sub 0.8/C/sub 0.2/ emitter transistors are presented. Emitter Gummel numbers exceeding 10/sup 14/ s/cm/sup 4/ are reported for the first time in this type of structure. The high values obtained for G/sub E/ are believed to be due to the valance band discontinuity between the Si/sub 0.8/C/sub 0.2/ layer and the crystalline part of the emitter, which effectively blocks the minority carrier injection from the base into the noncrystalline part of the emitter.Peer ReviewedPostprint (published version