Simulations of GRB Jets in a Stratified External Medium: Dynamics, Afterglow Lightcurves, Jet Breaks and Radio Calorimetry

The dynamics of GRB jets during the afterglow phase is most reliably and accurately modelled using hydrodynamic simulations. All published simulations, however, have considered only a uniform external medium, while a stratified external medium is expected around long duration GRB progenitors. Here we present simulations of the dynamics of GRB jets and the resulting afterglow emission for both uniform and stratified external media with $\rho \propto r^{-k}$ for k = 0, 1, 2. The simulations are performed in 2D using the special relativistic version of the Mezcal code. The dynamics for stratified external media are broadly similar to those derived for expansion into a uniform external medium. The jet half-opening angle start increasing logarithmically with time once the Lorentz factor drops below 1/theta_0. For larger k values the lateral expansion is faster at early times and slower at late times with the jet expansion becoming Newtonian and slowly approaching spherical symmetry over progressively longer timescales. We find that contrary to analytic expectations, there is a reasonably sharp jet break in the lightcurve for k = 2 although the shape of the break is affected more by the viewing angle than by the slope of the external density profile. Steeper density profiles are found to produce more gradual jet breaks while larger viewing angles cause smoother and later appearing jet breaks. The counter-jet becomes visible as it becomes sub-relativistic, and for k=0 this results in a clear bump-like feature in the light curve. However, for larger k values the jet decelerates more gradually, causing only a mild flattening in the radio light curve that might be hard to discern when k=2. Late time radio calorimetry is likely to consistently over-estimate the true energy by up to a factor of a few for k=2, and either over-predict or under-predict it by a smaller factor for k = 0,1.Comment: 10 pages, 13 figures, submitted to Ap

An Andean Musical Structure That Defies Borders

In many existing repertoires of traditional music in the South American Andean area a type of melodic structure that seems to refer to a common antecedent can be detected, even though its adaptation to the various genres is manifested through musical variants. The comparative analysis of these expressions (some belonging to the heptatonic modal and tonal systems of European origin and other that are typical of the anhemitonic pentatonic Andean system) allows a possible influence of the latter on the former to be hypothesized. This proposal aims to advance in this direction and will try to highlight one of the characteristics that give cohesion to musical expressions from a cultural area affected by processes of transculturation and identity affirmation. To achieve new knowledge about this phenomenon one has to analyze both the musical structures and the implications of its use in repertoires emerging at different times and in different circumstances, linked to the search and affirmation of an Andean cultural identity through organized sound.  In many existing repertoires of traditional music in the South American Andean area a type of melodic structure that seems to refer to a common antecedent can be detected, even though its adaptation to the various genres is manifested through musical variants. The comparative analysis of these expressions (some belonging to the heptatonic modal and tonal systems of European origin and other that are typical of the anhemitonic pentatonic Andean system) allows a possible influence of the latter on the former to be hypothesized. This proposal aims to advance in this direction and will try to highlight one of the characteristics that give cohesion to musical expressions from a cultural area affected by processes of transculturation and identity affirmation. To achieve new knowledge about this phenomenon one has to analyze both the musical structures and the implications of its use in repertoires emerging at different times and in different circumstances, linked to the search and affirmation of an Andean cultural identity through organized sound.

Women\u27s rights in iran during the years of the shah, ayatollah khomeini, and khamenei

Women\u27s rights have been a historically controversial issue. This is no exception in Iran, where the struggle between modernization and keeping with traditional Islamic values has been a topic of constant disagreement between political leaders. Women in Iran have experienced many changes in their personal rights and freedoms throughout the decades. This research focuses on religion and culture, the policies of the main leaders of Iran in the past decades, and the role of non-governmental organizations as factors that expand or limit the rights and freedoms of women. It attempts to identify which factor is mostly responsible for the position that women have been historically placed in. The intent of this thesis is to research the rights and conditions of women in Iran.In general the question could be proposed as are the lives of women in Iran better off today than in the past? In the western world there are many stereotypes that are oftentimes attached to women, such as the notions that they are not allowed to pursue an education or career and that they do not have any legal rights. Evidence shows that these notions are not accurate in contemporary Iran, and that women have made significant strides in gaining their rights and freedoms. Through the analysis of several case studies, literature reviews, and statistical evidence, this thesis seeks to identify the factors that most affect women\u27s rights and freedoms. By analyzing the factors that have historically placed women at a disadvantage in Iranian society, and better understanding their lives, this thesis aims to fight the stereotypes placed upon them as well as raise awareness for the continuing plight of women in Iran today

Empiricism and stochastics in cellular automaton modeling of urban land use dynamics

An increasing number of models for predicting land use change in regions of rapidurbanization are being proposed and built using ideas from cellular automata (CA)theory. Calibrating such models to real situations is highly problematic and to date,serious attention has not been focused on the estimation problem. In this paper, wepropose a structure for simulating urban change based on estimating land usetransitions using elementary probabilistic methods which draw their inspiration fromBayes' theory and the related ?weights of evidence? approach. These land use changeprobabilities drive a CA model ? DINAMICA ? conceived at the Center for RemoteSensing of the Federal University of Minas Gerais (CSR-UFMG). This is based on aneight cell Moore neighborhood approach implemented through empirical land useallocation algorithms. The model framework has been applied to a medium-size townin the west of São Paulo State, Bauru. We show how various socio-economic andinfrastructural factors can be combined using the weights of evidence approach whichenables us to predict the probability of changes between land use types in differentcells of the system. Different predictions for the town during the period 1979-1988were generated, and statistical validation was then conducted using a multipleresolution fitting procedure. These modeling experiments support the essential logicof adopting Bayesian empirical methods which synthesize various information aboutspatial infrastructure as the driver of urban land use change. This indicates therelevance of the approach for generating forecasts of growth for Brazilian citiesparticularly and for world-wide cities in general

The impact of clothing experience as a child when buying clothes for our own children

Dissertation presented as the partial requirement for obtaining a Master's degree in Information Management, specialization in Marketing IntelligenceChildhood processes have a strong impact on identity formation but there is still poor understanding about how these process works as children grow. From early ages an individual is constantly being shaped by who surrounds him and that brings consequences for his development as a child and later as an adult. My particular question of the shopping habits of children clothing gives me the chance to explore childhood process and contribute with my research to this topic. To be able to take conclusions I will make a survey with a few open-ended questions almost as if it was a reflective interview. My target are Portuguese parents who have children under de age of 12. My research aims to understand how the experience these parents had during their childhood about how they were dressed by their parents shaped the way they dress their own children. Are these parents doing to their children the same as their parents did with them? Is it different? In what way? And why is that? Would they like to change something in the way they were raised? Are they making that change on how they are raising their children

Transformation des mosaïques de la forêt-savane par des pratiques agroforestières en Afrique subsaharienne (Guinée et Cameroun)

Une analyse comparative de l'évolution spatio-temporelle des mosaïques de forêt-savane soumises aux pratiques agricoles a été réalisée dans deux situations tropicales humides (Guinée forestière, Centre Cameroun). Au cours des trois dernières décennies, l'emprise spatiale des systèmes de culture agroforestiers ou " agroforêts " associant cultures pérennes (cacaoyer, caféier...) et végétation sub-spontanée a fortement augmenté dans ces deux régions. En Guinée ces systèmes, principalement à base de caféiers, se sont développés au détriment d'espaces autrefois consacrés aux cultures annuelles (riz pluvial) en rotation avec des jachères arborées ou arbustives. Mais une dynamique d'extension des agroforêts à caféiers dans les îlots de savane est amorcée. Au Centre Cameroun, les agroforêts, principalement à base de cacaoyers, ont été implantées tout d'abord dans des reliques forestières et des forêts galeries. Ensuite, faute de réserves de terres forestières, les agriculteurs ont innové en développant sur d'importantes surfaces des agroforêts dans les zones de savane à graminées, traditionnellement dévolues aux cultures annuelles vivrières. Cette dynamique anthropique, loin d'être destructrice, contribue à la constitution d'un écosystème " forestier cultivé " dans des zones originellement dominées par la savane et la forêt secondaire. Face à ces processus relativement récents, la question de la durabilité des agroforêts est posée du fait de l'accroissement de la demande en produits alimentaires et donc des besoins en terre pour les cultures vivrières annuelles. (Résumé d'auteur

Desempenho agronômico de sorgo sacarino no agreste alagoano em função da densidade e espaçamento de plantio.

A cana-de-açúcar é colhida em Alagoas, em geral, entre os meses de setembro a março. No restante do ano ocorre a entressafra com a paralisação da moagem. Uma alternativa para aumentar a produção de bioenergia do Estado seria o prolongamento da safra com o uso de culturas com potencial para a produção de etanol durante o período de entressafra e uma das alternativas que poderiam ser utilizadas é o sorgo sacarino. O objetivo do trabalho foi avaliar a influência de diferentes espaçamentos e densidades de plantio de sorgo sacarino cultivado em usinas sucroalcooleiras na região Agreste do Estado de Alagoas. Foram avaliados três espaçamentos entre linhas (0,5m, 0,7m e 0,9m) e cinco densidades de plantio (100, 120, 140, 160 e 180 mil plantas.ha-1) no delineamento em parcela subdividida com três repetições. As densidades de plantio não afetaram as características avaliadas. O espaçamento 0,5m proporcionou maior produtividade de massa verde total, massa verde e seca de colmo e produtividade de panículas quando comparado ao espaçamento de 0,9m e maior produtividade de massa verde total em relação ao espaçamento 0,7m