Effect of Auger recombination and leakage on the droop in InGaN/GaN quantum well LEDs

We investigate the effect of the epitaxial structure and the acceptor doping profile on the efficiency droop in InGaN/GaN LEDs by the physics based simulation of experimental internal quantum efficiency (IQE) characteristics. The device geometry is an integral part of our simulation approach. We demonstrate that even for single quantum well LEDs the droop depends critically on the acceptor doping profile. The Auger recombination was found to increase stronger than with the third power of the carrier density and has been found to dominate the droop in the roll over zone of the IQE. The fitted Auger coefficients are in the range of the values predicted by atomistic simulations.

On the incremental validity of irrational beliefs to predict subjective well-being while controlling for personality factors

Resumen tomado de la publicaci??n

Java Applets for teaching quantum mechanics: Particle in a well

These Java Applets help to illustrate some of the difficult to grasp concepts of quantum mechanics. To run this Applet, use the 'Download as zip files' option. Make sure you extract the files first, then double click on the .html file to run the Applet. These are released as open access resources for the purpose of testing, and are to be deployed at the users own risk.

A few philosophical ruminations on the human condition and choosing to live well

The notion that life is meaningful through choosing to live well has historically received substantive attention in various philosophical circles, notably the ancient Greek philosophers Socrates, Plato, and Aristotle, and more recently several of the existentialists. In some respects, the idea of choosing to live well is a “thematization” of two widely-recognized, independent components of a meaningful life: happiness and authenticity. I develop this notion of choosing to live well by exploring, developing, and relating these conceptions of happiness and authenticity. By appealing to a very basic account of human nature that has found favor among a great number of people, I show how happiness and authenticity complement each other as conditions for the possibility of living meaningfully.

Well done Sam!

A Sam le preocupa cómo puede ayudar a su profesora Miss Miller. Para la lectura en voz alta de niños a partir de cinco años cumple con los requisitos del currículo de Inglaterra, Gales e Irlanda. Las ilustraciones están muy relacionadas con el texto, lo que permite a los alumnos predecir las palabras desconocidas al desarrollar un vocabulario basado en la imagen, lo que facilita la lectura. El texto es corto y relata una historia familiar.

Well, a crocodile can!

Un niño y una niña, con preguntas sencillas,señalan las características únicas y capacidades de diversos animales. Como que una pulga puede saltar noventa veces su altura y un camaleón sacar una lengua, que es tan larga como su cuerpo o un elefante mover las orejas. Las ilustraciones están en desplegables en relieve.

Eat well.

Es vital que los niños aprenden las mejores formas de cuidar de sí mismos y sean conscientes de los peligros potenciales de su salud a una edad temprana. Para ello, a los jóvenes lectores se les muestra la pirámide alimenticia y aprendan a reconocer los diferentes tipos de alimentos y saber para que lo necesita su cuerpo. Unos alimentos les proporcionan energía y otros,les ayudan a crecer. Reúne las características para ser utilizado como libro de lectura.

The eudaimonic component of satisfaction with life and psychological well-being in Spanish cultures

Resumen tomado de la publicaci??n

How well do regional or national Breeding Bird Survey data predict songbird population trends at an intact boreal site?

A study to monitor boreal songbird trends was initiated in 1998 in a relatively undisturbed and remote part of the boreal forest in the Northwest Territories, Canada. Eight years of point count data were collected over the 14 years of the study, 1998-2011. Trends were estimated for 50 bird species using generalized linear mixed-effects models, with random effects to account for temporal (repeat sampling within years) and spatial (stations within stands) autocorrelation and variability associated with multiple observers. We tested whether regional and national Breeding Bird Survey (BBS) trends could, on average, predict trends in our study area. Significant increases in our study area outnumbered decreases by 12 species to 6, an opposite pattern compared to Alberta (6 versus 15, respectively) and Canada (9 versus 20). Twenty-two species with relatively precise trend estimates (precision to detect > 30% decline in 10 years; observed SE ≤ 3.7%/year) showed nonsignificant trends, similar to Alberta (24) and Canada (20). Precision-weighted trends for a sample of 19 species with both reliable trends at our site and small portions of their range covered by BBS in Canada were, on average, more negative for Alberta (1.34% per year lower) and for Canada (1.15% per year lower) relative to Fort Liard, though 95% credible intervals still contained zero. We suggest that part of the differences could be attributable to local resource pulses (insect outbreak). However, we also suggest that the tendency for BBS route coverage to disproportionately sample more southerly, developed areas in the boreal forest could result in BBS trends that are not representative of range-wide trends for species whose range is centred farther north.

How well do we understand and evaluate climate change feedback processes?

Processes in the climate system that can either amplify or dampen the climate response to an external perturbation are referred to as climate feedbacks. Climate sensitivity estimates depend critically on radiative feedbacks associated with water vapor, lapse rate, clouds, snow, and sea ice, and global estimates of these feedbacks differ among general circulation models. By reviewing recent observational, numerical, and theoretical studies, this paper shows that there has been progress since the Third Assessment Report of the Intergovernmental Panel on Climate Change in (i) the understanding of the physical mechanisms involved in these feedbacks, (ii) the interpretation of intermodel differences in global estimates of these feedbacks, and (iii) the development of methodologies of evaluation of these feedbacks (or of some components) using observations. This suggests that continuing developments in climate feedback research will progressively help make it possible to constrain the GCMs’ range of climate feedbacks and climate sensitivity through an ensemble of diagnostics based on physical understanding and observations.

How well do high resolution models reproduce tropical convection?

Cascade is a multi-institution project studying the temporal and spatial organization of tropical convective systems. While cloud resolving numerical models can reproduce the observed diurnal cycle of such systems they are sensitive to the chosen resolution. As part of this effort, we are comparing results from the Met. Office Unified Model to data from the Global Earth Radiation Budget satellite instrument over the African Monsoon Interdisciplinary Analyses region of North Africa. We use a variety of mathematical techniques to study the outgoing radiation and the evolution of properties such as the cloud size distribution. The effectiveness of various model resolutions is tested with a view to determining the optimum balance between resolution and the need to reproduce the observations.