884 resultados para HALF-LIVES


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For more than half of a century, Colombia has been living in a state of violence, a nationwide political violence. As the time goes by, this situation gets even worse. Now the violence is implanted for different interests, such as personal, political, social and economical interests. For this reason, the information for this thesis was gathered from the time of the independence, through the era of violence until today; considering a reflection that begins with the perspective of Marx, passing by a theoretical compilation of the conflict, with an anthropological, psychological, biological and sociological perspective. In addition, different theories about violence have been studied to recognize the ideological approach of the different armed movements that have emerged in Colombia. Statistical, economical and social data including class struggle, social stratification, exclusion and gender perspective among others, have been considered from an anthropological and interdisciplinary approach for studying the violence. A strong interest in the social reintegration process, through an ethnographic study, based on the actors backgrounds, their lives, experiences and their geographical location have provided information that will allow to know the reality of those who are living in the process, those who survive it and those who go on with their lives in society, and those who after doing it return to the armed groups. Population displaced by violence, refugees, has contributed to this study about their possibilities to return to the society or to be excluded by it. With this purpose, a theoretical and a documentary analysis as well as fieldwork have been done, trying to bring forward tools and guidelines to make some progress in developing effective solutions for social integration of Colombian armed conflict victims.

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Contrary to the antiferromagnetic and insulating character of bulk NiO, one-dimensional chains of this material can become half metallic due to the lower coordination of their atoms. Here we present ab initio electronic structure and quantum transport calculations of ideal infinitely long NiO chains and of more realistic short ones suspended between Ni electrodes. While infinite chains are insulating, short suspended chains are half-metallic minority-spin conductors that displays very large magnetoresistance and a spin-valve behavior controlled by a single atom.

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The magnetic field strength at birth is arguably one of the most important properties to determine the evolutionary path of a neutron star. Objects with very high fields, collectively known as magnetars, are characterized by high X-ray quiescent luminosities, occurrence of outbursts, and, for some of them, sporadic giant flares. While the magnetic field strength is believed to drive their collective behaviour, however, the diversity of their properties, and, especially, the observation of magnetar-like bursts from “low-field” pulsars, has been a theoretical puzzle. In this review, we discuss results of long-term simulations following the coupled evolution of the X-ray luminosity and the timing properties for a large, homogeneous sample of X-ray emitting isolated neutron stars, accounting for a range of initial magnetic field strengths, envelope compositions, and neutron star masses. In addition, by following the evolution of magnetic stresses within the neutron star crust, we can also relate the observed magnetar phenomenology to the physical properties of neutron stars, and in particular to their age and magnetic field strength and topology. The dichotomy of “high-B” field pulsars versus magnetars is naturally explained, and occasional outbursts from old, low B-field neutron stars are predicted. We conclude by speculating on the fate of old magnetars, and by presenting observational diagnostics of the neutron star crustal field topology.

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A beautiful sweeping story of two sisters caught up in the events of the Nigerian civil war, ending in chilling violence which shocked the entire world.

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In this thesis I argue that dominant ways of imagining modernity constitute a modern imaginary that carries with it particular expectations concerning modern places, spaces, emotions, and affects as well as expectations concerning the place of religion and enchantment in the modern world. I argue that this modern imaginary and the expectations it entails works to conceal and trivialize supra-rational beliefs and behaviours in scholarship but also in the lives of individuals. I focus on one particular subset of the supra-rational beliefs and behaviours that modern imaginary conceals and trivializes, namely beliefs and behaviours associated with lucky and protective objects. I also focus on the ways the modern imaginary conceals the presence and prevalence of these objects and the beliefs and behaviours they entail in one particular context, namely Montréal, Québec. I argue that these supra-rational beliefs and behaviours constitute a subjunctive mode for understanding and experiencing daily life and describe how the modern imaginary works to discredit this subjunctive register. Finally, I argue that scholars must begin to recognize and examine this subjunctive mode and the playful engagement with half-belief it involves.