Aportaciones de la semántica cognitiva a la formación de palabras por composición

La composición es un proceso de formación de palabras, cuya productividad se sustenta en la creación ilimitada de nuevas voces transparentes semánticamente (apoyacabeza, destapabotellas, etc.). No obstante, son también numerosos aquellos compuestos que presentan idiomaticidad u opacidad semántica (ahogabecerro ‘árbol’, bienmesabe ‘dulce’, etc.). Partiendo de estos últimos compuestos, el propósito de este trabajo es mostrar que la semántica cognitiva resulta un modelo teórico idóneo para dar cuenta de los distintos procesos semánticos (metafóricos y metonímicos) que explican la significación de determinados compuestos. Para llevar a cabo este objetivo, se analizan a la luz de los presupuestos de la semántica cognitiva, los compuestos léxicos extraídos del Diccionario de americanismos publicado por la Real Academia Española en 2010.The aim of this research is to show the application of Cognitive Semantics to the description of nominal compounding in American Spanish. Compounding is a productive morphologic process used to create words with a transparent meaning (apoyacabeza ‘head restraint’, destapabotellas ‘bottle opener’ etc.). However, many compounds also have an important level of idiomaticity (ahogabecerro ‘tree’, bienmesabe ‘candy’ etc.). The paper shows that Cognitive Semantics can explain the semantic opacity of these idiomatic compounds on the basis of metaphoric and metonymic processes. The data are extracted from the Diccionario de americanismos published by the Real Academia Española

Screening of the quantum-confined Stark effect in AlN/GaN nanowire superlattices by Germanium doping

We report on electrostatic screening of polarization-induced internal electric fields in AlN/GaN nanowire heterostructures with Germanium-doped GaN nanodiscs embedded between AlN barriers. The incorporation of Germanium at concentrations above $10^{20}\,\text{cm}^{-3}$ shifts the photoluminescence emission energy of GaN nanodiscs to higher energies accompanied by a decrease of the photoluminescence decay time. At the same time, the thickness-dependent shift in emission energy is significantly reduced. In spite of the high donor concentration a degradation of the photoluminescence properties is not observed.Comment: Manuscript including Supplemental material (15 pages, 5 figures

Absolute risk and risk factors for stroke mortality in patients with end stage kidney disease (ESKD): population-based cohort study using data linkage

INTRODUCTION: People with end-stage kidney disease (ESKD) have up to 30-fold higher risk of stroke than the general population. OBJECTIVE: To determine risk factors associated with stroke death in the ESKD population. METHODS: We identified all patients with incident ESKD in Australia (1980-2013) and New Zealand (1988-2012) from the Australian and New Zealand Dialysis and Transplant Registry (ANZDATA) registry. We ascertained underlying cause of death from data linkage with national death registries and risk factors from ANZDATA. Using a competing risks multivariable regression model, we estimated cumulative incidence of stroke and non-stroke deaths, and risk factors for stroke deaths (adjusted sub-HR, SHR). RESULTS: We included 60 823 people with ESKD. There were 941 stroke deaths and 33 377 non-stroke deaths during 381 874 person-years of follow-up. Overall, the cumulative incidence of stroke death was 0.9% and non-stroke death was 36.8% 5 years after starting ESKD treatment. The risk of stroke death was higher at older ages (SHR 1.92, 95% CI 1.45 to 2.55), in females (SHR 1.41, 95% CI 1.21 to 1.64), in people with cerebrovascular disease (SHR 2.39, 95% CI 1.99 to 2.87), with ESKD caused by hypertensive/renovascular disease (SHR 1.39, 95% CI 1.09 to 1.78) or polycystic kidney disease (SHR 1.38, 95% CI 1.00 to 1.90), with earlier year of ESKD treatment initiation (SHR 1.93, 95% CI 1.56 to 2.39) and receiving dialysis (transplant vs haemodialysis SHR 0.27, 95% CI 0.09 to 0.84). CONCLUSION: Patients with ESKD with higher risk of stroke death are older, women, with cerebrovascular disease, with hypertensive/renovascular or polycystic kidney disease cause of ESKD, with earlier year of ESKD treatment and receiving dialysis. These groups may benefit from targeted stroke prevention interventions

Long-lived excitons in GaN/AlN nanowire heterostructures

GaN/AlN nanowire heterostructures can display photoluminescence (PL) decay times on the order of microseconds that persist up to room temperature. Doping the GaN nanodisk insertions with Ge can reduce these PL decay times by two orders of magnitude. These phenomena are explained by the three-dimensional electric field distribution within the GaN nanodisks, which has an axial component in the range of a few MV/cm associated to the spontaneous and piezoelectric polarization, and a radial piezoelectric contribution associated to the shear components of the lattice strain. At low dopant concentrations, a large electron-hole separation in both the axial and radial directions is present. The relatively weak radial electric fields, which are about one order of magnitude smaller than the axial fields, are rapidly screened by doping. This bidirectional screening leads to a radial and axial centralization of the hole underneath the electron, and consequently, to large decreases in PL decay times, in addition to luminescence blue shifts