991 resultados para powder technology
Resumo:
The increasing number of bomb attacks involving improvised explosive devices, as well as the nature of the explosives, give rise to concern among safety and law enforcement agencies. The substances used in explosive charges are often everyday products diverted from their primary licit applications. Thus, reducing or limiting their accessibility for prevention purposes is difficult. Ammonium nitrate, employed in agriculture as a fertiliser, is used worldwide in small and large homemade bombs. Black powder, dedicated to hunting and shooting sports, is used illegally as a filling in pipe bombs causing extensive damage. If the main developments of instrumental techniques in explosive analysis have been constantly pushing the limits of detection, their actual contribution to the investigation of explosives in terms of source discrimination is limited. Forensic science has seen the emergence of a new technology, isotope ratio mass spectrometry (IRMS), that shows promising results. Its very first application in forensic science dates back to 1979. Liu et al. analysed cannabis plants coming from different countries [Liu et al. 1979]. This preliminary study highlighted its potential to discriminate specimens coming from different sources. Thirty years later, the keen interest in this new technology has given rise to a flourishing number of publications in forensic science. The countless applications of IRMS to a wide range of materials and substances attest to its success and suggest that the technique is ready to be used in forensic science. However, many studies are characterised by a lack of methodology and fundamental data. They have been undertaken in a top-down approach, applying this technique in an exploratory manner on a restricted sampling. This manner of procedure often does not allow the researcher to answer a number of questions, such as: do the specimens come from the same source, what do we mean by source or what is the inherent variability of a substance? The production of positive results has prevailed at the expense of forensic fundamentals. This research focused on the evaluation of the contribution of the information provided by isotopic analysis to the investigation of explosives. More specifically, this evaluation was based on a sampling of black powders and ammonium nitrate fertilisers coming from known sources. Not only has the methodology developed in this work enabled us to highlight crucial elements inherent to the methods themselves, but also to evaluate both the longitudinal and transversal variabilities of the information. First, the study of the variability of the profile over time was undertaken. Secondly, the variability of black powders and ammonium nitrate fertilisers within the same source and between different sources was evaluated. The contribution of this information to the investigation of explosives was then evaluated and discussed. --------------------------------------------------------------------------------------------------- Le nombre croissant d'attentats à la bombe impliquant des engins explosifs artisanaux, ainsi que la nature des charges explosives, constituent une préoccupation majeure pour les autorités d'application de la loi et les organismes de sécurité. Les substances utilisées dans les charges explosives sont souvent des produits du quotidien, détournés de leurs applications licites. Par conséquent, réduire ou limiter l'accessibilité de ces produits dans un but de prévention est difficile. Le nitrate d'ammonium, employé dans l'agriculture comme engrais, est utilisé dans des petits et grands engins explosifs artisanaux. La poudre noire, initialement dédiée à la chasse et au tir sportif, est fréquemment utilisée comme charge explosive dans les pipe bombs, qui causent des dommages importants. Si les développements des techniques d'analyse des explosifs n'ont cessé de repousser les limites de détection, leur contribution réelle à l'investigation des explosifs est limitée en termes de discrimination de sources. Une nouvelle technologie qui donne des résultats prometteurs a fait son apparition en science forensique: la spectrométrie de masse à rapport isotopique (IRMS). Sa première application en science forensique remonte à 1979. Liu et al. ont analysé des plants de cannabis provenant de différents pays [Liu et al. 1979]. Cette étude préliminaire, basée sur quelques analyses, a mis en évidence le potentiel de l'IRMS à discriminer des spécimens provenant de sources différentes. Trente ans plus tard, l'intérêt marqué pour cette nouvelle technologie en science forensique se traduit par un nombre florissant de publications. Les innombrables applications de l'IRMS à une large gamme de matériaux et de substances attestent de son succès et suggèrent que la technique est prête à être utilisée en science forensique. Cependant, de nombreuses études sont caractérisées par un manque de méthodologie et de données fondamentales. Elles ont été menées sans définir les hypothèses de recherche et en appliquant cette technique de façon exploratoire sur un échantillonnage restreint. Cette manière de procéder ne permet souvent pas au chercheur de répondre à un certain nombre de questions, tels que: est-ce que deux spécimens proviennent de la même source, qu'entend-on par source ou encore quelle est l'intravariabilité d'une substance? La production de résultats positifs a prévalu au détriment des fondamentaux de science forensique. Cette recherche s'est attachée à évaluer la contribution réelle de l'information isotopique dans les investigations en matière d'explosifs. Plus particulièrement, cette évaluation s'est basée sur un échantillonnage constitué de poudres noires et d'engrais à base de nitrate d'ammonium provenant de sources connues. La méthodologie développée dans ce travail a permis non seulement de mettre en évidence des éléments cruciaux relatifs à la méthode d'analyse elle-même, mais également d'évaluer la variabilité de l'information isotopique d'un point de vue longitudinal et transversal. Dans un premier temps, l'évolution du profil en fonction du temps a été étudiée. Dans un second temps, la variabilité du profil des poudres noires et des engrais à base de nitrate d'ammonium au sein d'une même source et entre différentes sources a été évaluée. La contribution de cette information dans le cadre des investigations d'explosifs a ensuite été discutée et évaluée.
Resumo:
This report provides our advice to the Minister for Education and Science on the application for designation as a university made by Waterford Institute of Technology (WIT). WIT submitted an application for designation in February 2006. There is a statutory procedure for the creation of a new university under Section 9 of the Universities Act 1997. We were asked to advise the Minister on the merits of the submission in order for her to provide guidance to Government on whether such a formal statutory review should be initiated. It is not a straightforward task to advise on this case for several reasons. These include the facts that: the regulatory environment for Institutes of Technology has changed significantly since WIT made their application; and the designation of any IoT would potentially challenge the government’s current higher education policy. So our report has to range more widely than the merits of the WIT application, taken at face value.
Resumo:
Learning is changing. A pivotal force in bringing about this change is the use of information and communications technology (ICT) which provides richer, more immediate, world-relevant educational resources and opportunities. When used well, ICT enriches learning and enhances teaching. It invigorates classroom activities and is a powerful motivational tool that encourages learners to progress in more personalised and self-directed ways. Ireland has achieved rapid change and growth in the past decade, but to sustain this we must prepare the next generation for the knowledge society in which they will live. The challenge we face is to ensure that the emphasis on ICT in schools shifts, in the immediate future, from technology provision to a focus on its deliberate use by the learner. Fostering personal creativity has always been a desirable educational value. The pursuit of creativity and inventiveness are now pivotal skills in a knowledge economy and the embedding of ICT in learning can greatly facilitate their development. Web 2.0 will facilitate greater interactivity and enable greater levels of user-generated content. It is crucial that young people acquire the ICT and related skills to support these new opportunities.
Resumo:
Technology (i.e. tools, methods of cultivation and domestication, systems of construction and appropriation, machines) has increased the vital rates of humans, and is one of the defining features of the transition from Malthusian ecological stagnation to a potentially perpetual rising population growth. Maladaptations, on the other hand, encompass behaviours, customs and practices that decrease the vital rates of individuals. Technology and maladaptations are part of the total stock of culture carried by the individuals in a population. Here, we develop a quantitative model for the coevolution of cumulative adaptive technology and maladaptive culture in a 'producer-scrounger' game, which can also usefully be interpreted as an 'individual-social' learner interaction. Producers (individual learners) are assumed to invent new adaptations and maladaptations by trial-and-error learning, insight or deduction, and they pay the cost of innovation. Scroungers (social learners) are assumed to copy or imitate (cultural transmission) both the adaptations and maladaptations generated by producers. We show that the coevolutionary dynamics of producers and scroungers in the presence of cultural transmission can have a variety of effects on population carrying capacity. From stable polymorphism, where scroungers bring an advantage to the population (increase in carrying capacity), to periodic cycling, where scroungers decrease carrying capacity, we find that selection-driven cultural innovation and transmission may send a population on the path of indefinite growth or to extinction.
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In this thesis, I examine the diffusion process for a complex medical technology, the PET scanner, in two different health care systems, one of which is more market-oriented (Switzerland) and the other more centrally managed by a public agency (Quebec). The research draws on institutional and socio-political theories of the diffusion of innovations to examine how institutional contexts affect processes of diffusion. I find that diffusion proceeds more rapidly in Switzerland than in Quebec, but that processes in both jurisdictions are characterized by intense struggles among providers and between providers and public agencies. I show that the institutional environment influences these processes by determining the patterns of material resources and authority available to actors in their struggles to strategically control the technology, and by constituting the discursive resources or institutional logics on which actors may legitimately draw in their struggles to give meaning to the technology in line with their interests and values. This thesis illustrates how institutional structures and meanings manifest themselves in the context of specific decisions within an organizational field, and reveals the ways in which governance structures may be contested and realigned when they conflict with interests that are legitimized by dominant institutional logics. It is argued that this form of contestation and readjustment at the margins constitutes one mechanism by which institutional frameworks are tested, stretched and reproduced or redefined.
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The decision to publish educational materials openly and under free licenses brings up the challenge of doing it in a sustainable way. Some lessons can be learned from the business models for production, maintenance and distribution of Free and Open Source Software. The Free Technology Academy (FTA) has taken on these challenges and has implemented some of these models. We briefly review the FTA educational programme, methodologies and organisation, and see to which extent these models are proving successful in the case of the FTA.
Resumo:
The place of technology in the development of coherent educational responses to environmental and socio-economic disruption is here placed under scrutiny. One emerging area of interest is the role of technology in addressing more complex learning futures, and more especially in facilitating individual and social resilience, or the ability to manage and overcome disruption. However, the extent to which higher education practitioners can utilise technology to this end is framed by their approaches to the curriculum, and the socio-cultural practices within which they are located. This paper discusses how open education might enable learners to engage with uncertainty through social action within a form of higher education that is more resilient to economic, environmental and energy-related disruption. It asks whether open higher education can be (re)claimed by users and communities within specific contexts and curricula, in order to engage with an uncertain world.
Resumo:
La televisió està en crisi. Les noves tecnologies i els dispositius han fragmentat les audiències de televisió en segments més petits. En aquest informe, Marissa Gluck i Meritxell Roca Sales examinen l'explosió dels mitjans de comunicació que han impulsat aquesta fragmentació.
Resumo:
The development of markets for technology has eased the acquisition of technology and reshaped the innovation strategies of firms that we classify as producers of innovations or as imitators. Innovative activities of firms include research, acquisition of technology and downstream activities. Within an industry, firms producing innovations tend to conduct more research and downstream activities than those imitating innovations. Acquisition of technology is equally important for both. To implement innovation strategies, firms producing innovations require both the capability to scan the external environment for technology and the capability to integrate new technology. Firms producing innovations require both, while firms imitating innovations require scan capabilities only
Resumo:
In visceral leishmaniasis, phlebotomine vectors are targets for control measures. Understanding the ecosystem of the vectors is a prerequisite for creating these control measures. This study endeavours to delineate the suitable locations of Phlebotomus argentipes with relation to environmental characteristics between endemic and non-endemic districts in India. A cross-sectional survey was conducted on 25 villages in each district. Environmental data were obtained through remote sensing images and vector density was measured using a CDC light trap. Simple linear regression analysis was used to measure the association between climatic parameters and vector density. Using factor analysis, the relationship between land cover classes and P. argentipes density among the villages in both districts was investigated. The results of the regression analysis indicated that indoor temperature and relative humidity are the best predictors for P. argentipes distribution. Factor analysis confirmed breeding preferences for P. argentipes by landscape element. Minimum Normalised Difference Vegetation Index, marshy land and orchard/settlement produced high loading in an endemic region, whereas water bodies and dense forest were preferred in non-endemic sites. Soil properties between the two districts were studied and indicated that soil pH and moisture content is higher in endemic sites compared to non-endemic sites. The present study should be utilised to make critical decisions for vector surveillance and controlling Kala-azar disease vectors.
Resumo:
Human glandular kallikrein 2 (hK2) is a trypsin-like serine protease expressed predominantly in the prostate epithelium. Recently, hK2 has proven to be a useful marker that can be used in combination with prostate specific antigen for screening and diagnosis of prostate cancer. The cleavage by hK2 of certain substrates in the proteolytic cascade suggest that the kallikrein may be involved in prostate cancer development; however, there has been very little other progress toward its biochemical characterization or elucidation of its true physiological role. In the present work, we adapt phage substrate technology to study the substrate specificity of hK2. A phage-displayed random pentapeptide library with exhaustive diversity was generated and then screened with purified hK2. Phages displaying peptides susceptible to hK2 cleavage were amplified in eight rounds of selection and genes encoding substrates were transferred from the phage to a fluorescent system using cyan fluorescent protein (derived from green fluorescent protein) that enables rapid determination of specificity constants. This study shows that hK2 has a strict preference for Arg in the P1 position, which is further enhanced by a Ser in P'1 position. The scissile bonds identified by phage display substrate selection correspond to those of the natural biological substrates of hK2, which include protein C inhibitor, semenogelins, and fibronectin. Moreover, three new putative hK2 protein substrates, shown elsewhere to be involved in the biology of the cancer, have been identified thus reinforcing the importance of hK2 in prostate cancer development.
Resumo:
The principal focus of the PhD thesis lies in the Social Software area and the appropriation of technology in "non-Western" societies taking the example of Bulgaria. The term "non-Western" is used to explain places considered technologically underdeveloped. The aims have been to capture how Bulgarian users creatively interpret and appropriate Internet identifying the sociocultural, political and subjective conditions in which that appropriation occurs, to identify emerging practices based on the interpretation and use of Internet and the impact they had on society and what conditions could influence the technological interpretation and the meaning these practices had for both users and social configuration of Internet as media in Bulgaria. An ethnographic approach has been used simultaneously in different online and offline contexts. On the one hand, this study is based on exploration of the Bulgarian Internet Space through online participant observation in forums and websites reviews and on the other hand, on semi-structured interviews with different types of users of the virtual platforms found, made both face to face and online and finally online participant observation at the same platforms. It is based on some contributions of the ethnographic work of Christine Hine in virtual environments and the notions of time and space of Barbara Czarniawska contextualized in the modern form of organization that occurs in a network of multiple and fragmented contexts across many movements.
Resumo:
BACKGROUND Assisted reproductive technology (ART) with washed semen can achieve pregnancy with minimal risk of horizontal and vertical transmission of chronic viral diseases (CVD) such as human immunodeficiency virus (HIV), hepati- tis C virus (HCV) and hepatitis B virus (HBV) among serodiscordant couples. How- ever, few studies have been made of the use made by these couples of ARTs or of the obstetric results achieved. MATERIALS AND METHODS In this retrospective study, 93 men who were seropositive for HIV, HCV or HBV and who underwent assisted reproduction treatment at our centre (Hospital Universitario Virgen de las Nieves, Granada, Spain) were included. Washed semen was tested to detect viral particles. Non-infected women were tested before and after each treatment, as were the neonates at birth and after three months. RESULTS A total of 62 sperm samples were washed, and none were positive for the detec- tion of viral molecules. Semen samples from 34 HBV positive males were not washed since the female partner had immunity to hepatitis B. In total, 38 clinical pregnancies were achieved (22% per cycle and 40.9% per couple) out of 173 cycles initiated, and 28 births were achieved (16.2% per cycle and 30.1% per couple), producing 34 live births. The rate of multiple pregnancies was 21.4%. Obstetric and neonatal results were similar in the groups of couples studied. At follow-up, no seroconversion was detected in the women or neonates. CONCLUSION Sperm washing and intracytoplasmic sperm injection are shown to be a safe and effective option for reducing the risk of transmission or super infection in serodiscordant or concordant couples who wish to have a child. Pregnancies ob- tained by ART in couples when the male is CVD infected achieve good obstetric and neonatal results.