Reduced L_1 level width and Coster-Kronig yields by relaxation and continuum interactions in atomic zinc

Calculations of the level width \gamma( L_1) and the f_12 and f_13 Coster-Kronig yields for atomic zinc have been performed with Dirac-Fock wave functions. For \gamma(L_1), a large deviation between theory and evaluated data exists. We include the incomplete orthogonality of the electron orbitals as well as the interchannel interaction of the decaying states. Orbital relaxation reduces the total rates in all groups of the electron-emission spectrum by about 10-20 %. Different, however, is the effect of the continuum interaction. The L_1-L_23X Coster-Kronig part of the spectrum is definitely reduced in its intensity, whereas the MM and MN spectra are slightly enhanced. This results in a reduction of Coster-Kronig yields, where for medium and heavy elements considerable discrepancies have been found in comparison to relativistic theory. Briefly, we discuss the consequences of our calculations for heavier elements.

Atomistic-continuum modeling of ultrafast laser-induced melting of silicon targets

In this work, we present an atomistic-continuum model for simulations of ultrafast laser-induced melting processes in semiconductors on the example of silicon. The kinetics of transient non-equilibrium phase transition mechanisms is addressed with MD method on the atomic level, whereas the laser light absorption, strong generated electron-phonon nonequilibrium, fast heat conduction, and photo-excited free carrier diffusion are accounted for with a continuum TTM-like model (called nTTM). First, we independently consider the applications of nTTM and MD for the description of silicon, and then construct the combined MD-nTTM model. Its development and thorough testing is followed by a comprehensive computational study of fast nonequilibrium processes induced in silicon by an ultrashort laser irradiation. The new model allowed to investigate the effect of laser-induced pressure and temperature of the lattice on the melting kinetics. Two competing melting mechanisms, heterogeneous and homogeneous, were identified in our big-scale simulations. Apart from the classical heterogeneous melting mechanism, the nucleation of the liquid phase homogeneously inside the material significantly contributes to the melting process. The simulations showed, that due to the open diamond structure of the crystal, the laser-generated internal compressive stresses reduce the crystal stability against the homogeneous melting. Consequently, the latter can take a massive character within several picoseconds upon the laser heating. Due to the large negative volume of melting of silicon, the material contracts upon the phase transition, relaxes the compressive stresses, and the subsequent melting proceeds heterogeneously until the excess of thermal energy is consumed. A series of simulations for a range of absorbed fluences allowed us to find the threshold fluence value at which homogeneous liquid nucleation starts contributing to the classical heterogeneous propagation of the solid-liquid interface. A series of simulations for a range of the material thicknesses showed that the sample width we chosen in our simulations (800 nm) corresponds to a thick sample. Additionally, in order to support the main conclusions, the results were verified for a different interatomic potential. Possible improvements of the model to account for nonthermal effects are discussed and certain restrictions on the suitable interatomic potentials are found. As a first step towards the inclusion of these effects into MD-nTTM, we performed nanometer-scale MD simulations with a new interatomic potential, designed to reproduce ab initio calculations at the laser-induced electronic temperature of 18946 K. The simulations demonstrated that, similarly to thermal melting, nonthermal phase transition occurs through nucleation. A series of simulations showed that higher (lower) initial pressure reinforces (hinders) the creation and the growth of nonthermal liquid nuclei. For the example of Si, the laser melting kinetics of semiconductors was found to be noticeably different from that of metals with a face-centered cubic crystal structure. The results of this study, therefore, have important implications for interpretation of experimental data on the kinetics of melting process of semiconductors.

A Computational Model for Observation in Quantum Mechanics

A computational model of observation in quantum mechanics is presented. The model provides a clean and simple computational paradigm which can be used to illustrate and possibly explain some of the unintuitive and unexpected behavior of some quantum mechanical systems. As examples, the model is used to simulate three seminal quantum mechanical experiments. The results obtained agree with the predictions of quantum mechanics (and physical measurements), yet the model is perfectly deterministic and maintains a notion of locality.

Automated Reasoning About Classical Mechanics

In recent years, researchers in artificial intelligence have become interested in replicating human physical reasoning talents in computers. One of the most important skills in this area is predicting how physical systems will behave. This thesis discusses an implemented program that generates algebraic descriptions of how systems of rigid bodies evolve over time. Discussion about the design of this program identifies a physical reasoning paradigm and knowledge representation approach based on mathematical model construction and algebraic reasoning. This paradigm offers several advantages over methods that have become popular in the field, and seems promising for reasoning about a wide variety of classical mechanics problems.

El continuum mente-cerebro : procesos sensoriales

Este libro es el resultado, no sólo de años de intensa actividad investigativa, sino también de la necesaria reflexión asociada, por parte de científicos de la neurociencia y de filósofos de distintas nacionalidades quienes, en un fructífero encuentro efectuado en Madrid, España, dieron un paso crucial en la construcción del arco conceptual que vincula, por no decir identifica, la actividad cerebral con la mente propiamente dicha. En consideración a la relevancia de la obra para nuestra comunidad científica, la Universidad del Rosario, fiel a su convicción de brindar apoyo e incentivar la divulgación del conocimiento, decidió participar por intermedio de su Centro Editorial en la publicación de esta primera edición en idioma español, con la certeza de estar contribuyendo al desarrollo de la investigación, mediante la difusión de los hallazgos en este importante y aun no conocido a cabalidad campo de la ciencia.

Age Continuum essay podcast

Participators Trevor Kettle and Yvonne Middlewick

Age continuum presentation podcast

Participators Trevor Kettle and Yvonne Middlewick

Java Applets for teaching quantum mechanics: Particle in a box

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. Please report any errors you find.

Java Applets for teaching quantum mechanics: Particle in a 2D box

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.

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.

Adolescentes em situação de vulnerabilidade social e o continuum risco-proteçãoriesgo-protección

Este es un estudio de casos múltiples realizado después de la inserción ecológica de los investigadores en los contextos de desarrollo de cuatro adolescentes en situación de vulnerabilidad social. Estos fueron seleccionados de un estudio más amplio llevado a cabo con 98 adolescentes de Brasil de dos grupos diferentes (G1 en situación de calle, y G2 en condición de extrema pobreza). Los adolescentes seleccionados tenía las calificaciones más altas y las más bajas de ajuste en sus respectivos grupos. Los cuatro jóvenes fueron descritos en cuanto a indicadores de ajuste, factores de riesgo y factores de protección, utilizando datos cuantitativos y datos del diario de campo. Los resultados mostraron puntos comunes y divergentes entre los casos y la existencia de un continuo de vulnerabilidad social. Este se relaciona más con la forma en que factores de riesgo y protección interactúan en la vida de cada adolescente, que con el contexto en el que viven (calle o familia).

El continuum autoimatge, imatge del centre, imatge de l'educació. 'El continuum autoimagen, imagen del centro, imagen de la educación'.

Es importante mantener un buen clima entre los profesores, pero también crear complicidades con los padres y los alumnos. Hace falta, pues, tener valores y comunicarlos adecuadamente, por lo cual es necesario cuidar las diversas imágenes de la escuela, especialmente la autoimagen profesional. Pero eso no surge espontáneamente: se debe crear, tractar, defender y comunicar nuestra realidad como profesionales y como institución de forma que el entorno nos muestre una imagen positiva y motivadora.

How to assess children's literacy, literacy developmental continuum. 'Cómo evaluar la alfabetización de los niños, alfabetización del desarrollo continuo'.

Es un instrumento de diagnóstico que permite a los profesores vincular la evaluación con la enseñanza, al proporcionar el mapa del recorrido de un niño en su etapa de aprendizaje del lenguaje oral y escrito. Es decir, es utilizado para evaluar y supervisar los progresos de los alumnos de párvulos a lo largo de los siguientes años de escolarización y, da una visión general del nivel alcanzado por éstos, así como, información sobre sus aptitudes hacia la lectura, la escritura y la comprensión.

The Continuum guide to geography education.

Esta guía, ordenada de forma alfabética, comprende los conceptos clave, los recursos, resultados de investigaciones, movimientos, cuestiones, debates, educadores y organizaciones que caracterizan la enseñanza de la geografía. Por lo cual, constituye un recurso tanto para los profesores de geografía como para los alumnos.