957 resultados para Gajdusek, D. Carleton (Daniel Carleton), 1923-2008.


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En el presente trabajo se intenta analizar diversos antecedentes de la última Dictadura Militar argentina, enfatizando los factores socio-laborales. Nuestra hipótesis más general es que algunas de las grandes violaciones de derechos humanos se vinculan a necesidades de la expansión o el ajuste del sistema capitalista y de sus procesos de trabajo Proponemos un enfoque distinto sobre el problema de la memoria. No solo nos interesa recuperar la memoria de los dirigentes y militantes, sino tratar de analizar el proceso en su totalidad e indagar sobre las causas de los conflictos. Consideramos que se han subestimado factores causales vinculados a las peculiaridades del capitalismo argentino y sus relaciones laborales

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El presente trabajo se centra en la indagación de los sentidos que construyen alumnos, docentes, directivos y padres respecto a los aspectos que valoran de la escuela media actual, las críticas que realizan y las expectativas en torno a la escolaridad en el nivel medio. Desde una perspectiva psicosocial comprensiva se entiende a la producción de sentido como un elemento vital implicado en la acción social y que da sustento a las prácticas sociales que despliegan los actores. Siguiendo esta perspectiva, la indagación acerca de los niveles de desencuentro y de encuentro en las producciones de sentido, podría brindar elementos que sirvan al momento de generar prácticas sociales alternativas en educación, repensar los vínculos entre los diferentes actores y atender a las demandas sociales emergentes que recaen sobre la escuela media. En esta comunicación se presentará un recorrido por diversos antecedentes empíricos tanto locales como extranjeros, así como la delimitación de esta problemática como objeto de indagación del presente proyecto de investigación, considerando los objetivos, los referentes teóricos y la perspectiva metodológica que supondrá el trabajo de campo

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We show that quantum information can be encoded into entangled states of multiple indistinguishable particles in such a way that any inertial observer can prepare, manipulate, or measure the encoded state independent of their Lorentz reference frame. Such relativistically invariant quantum information is free of the difficulties associated with encoding into spin or other degrees of freedom in a relativistic context.

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Recently, within the VISDEM project (EPSRC funded EP/C005848/1), a novel variational approximation framework has been developed for inference in partially observed, continuous space-time, diffusion processes. In this technical report all the derivations of the variational framework, from the initial work, are provided in detail to help the reader better understand the framework and its assumptions.

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This paper, addresses the problem of novelty detection in the case that the observed data is a mixture of a known 'background' process contaminated with an unknown other process, which generates the outliers, or novel observations. The framework we describe here is quite general, employing univariate classification with incomplete information, based on knowledge of the distribution (the 'probability density function', 'pdf') of the data generated by the 'background' process. The relative proportion of this 'background' component (the 'prior' 'background' 'probability), the 'pdf' and the 'prior' probabilities of all other components are all assumed unknown. The main contribution is a new classification scheme that identifies the maximum proportion of observed data following the known 'background' distribution. The method exploits the Kolmogorov-Smirnov test to estimate the proportions, and afterwards data are Bayes optimally separated. Results, demonstrated with synthetic data, show that this approach can produce more reliable results than a standard novelty detection scheme. The classification algorithm is then applied to the problem of identifying outliers in the SIC2004 data set, in order to detect the radioactive release simulated in the 'oker' data set. We propose this method as a reliable means of novelty detection in the emergency situation which can also be used to identify outliers prior to the application of a more general automatic mapping algorithm. © Springer-Verlag 2007.

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Parkinson's disease (PD) is associated with enhanced synchronization of neuronal network activity in the beta (15-30 Hz) frequency band across several nuclei of the basal ganglia (BG). Deep brain stimulation of the subthalamic nucleus (STN) appears to reduce this pathological oscillation, thereby alleviating PD symptoms. However, direct stimulation of primary motor cortex (M1) has recently been shown to be effective in reducing symptoms in PD, suggesting a role for cortex in patterning pathological rhythms. Here, we examine the properties of M1 network oscillations in coronal slices taken from rat brain. Oscillations in the high beta frequency range (layer 5, 27.8 +/- 1.1 Hz, n=6) were elicited by co-application of the glutamate receptor agonist kainic acid (400 nM) and muscarinic receptor agonist carbachol (50 mu M). Dual extracellular recordings, local application of tetrodotoxin and recordings in M1 micro-sections indicate that the activity originates within deep layers V/VI. Beta oscillations were unaffected by specific AMPA receptor blockade, abolished by the GABA type A receptor (GABAAR) antagonist picrotoxin and the gap-junction blocker carbenoxolone, and modulated by pentobarbital and zolpidem indicating dependence on networks of GABAergic interneurons and electrical coupling. High frequency stimulation (HFS) at 125 Hz in superficial layers, designed to mimic transdural/transcranial stimulation, generated gamma oscillations in layers 11 and V (incidence 95%, 69.2 +/- 7.3 Hz, n=17) with very fast oscillatory components (VFO; 100-250 Hz). Stimulation at 4 Hz, however, preferentially promoted theta activity (incidence 62.5%, 5.1 +/- 0.6 Hz, n=15) that effected strong amplitude modulation of ongoing beta activity. Stimulation at 20 Hz evoked mixed theta and gamma responses. These data suggest that within M1, evoked theta, gamma and fast oscillations may coexist with and in some cases modulate pharmacologically induced beta oscillations.

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The purpose of the present study is to test the case linkage principles of behavioural consistency and behavioural distinctiveness using serial vehicle theft data. Data from 386 solved vehicle thefts committed by 193 offenders were analysed using Jaccard's, regression and Receiver Operating Characteristic analyses to determine whether objectively observable aspects of crime scene behaviour could be used to distinguish crimes committed by the same offender from those committed by different offenders. The findings indicate that spatial behaviour, specifically the distance between theft locations and between dump locations, is a highly consistent and distinctive aspect of vehicle theft behaviour; thus, intercrime and interdump distance represent the most useful aspects of vehicle theft for the purpose of case linkage analysis. The findings have theoretical and practical implications for understanding of criminal behaviour and for the development of decision-support tools to assist police investigation and apprehension of serial vehicle theft offenders.

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We study the properties of radiation generated in ultralong fiber lasers and find an interesting link between these optical systems and the theory of weak wave turbulence. Experimental observations strongly suggest that turbulentlike weak interactions between the multitude of laser cavity modes are responsible for practical characteristics of ultralong fiber lasers such as spectra of the output radiation.

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E-atmospherics have been often analyzed in terms of functional features, leaving its characteristics' link to social capital co-creation as a fertile research area. Prior research have demonstrated the capacity of e-atmospherics' at modifying shopping habits towards deeper engagement. Little is known on how processes and cues emerging from the social aspects of lifestyle influence purchasing behavior. The anatomy of social dimension and ICT is the focus of this research, where attention is devoted to unpack the meanings and type of online mundane social capital creation. Taking a cross-product/services approach to better investigate social construction impact, our approach also involves both an emerging and a mature market where exploratory content analysis of landing page are done on Turkish and French web sites, respectively. We contend that by comprehending social capital, daily micro practices, habits and routine, a better and deeper understanding on e-atmospherics incumbent and potential effects on its multi-national e-customer will be acquired.

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Background: Research into mental-health risks has tended to focus on epidemiological approaches and to consider pieces of evidence in isolation. Less is known about the particular factors and their patterns of occurrence that influence clinicians’ risk judgements in practice. Aims: To identify the cues used by clinicians to make risk judgements and to explore how these combine within clinicians’ psychological representations of suicide, self-harm, self-neglect, and harm to others. Method: Content analysis was applied to semi-structured interviews conducted with 46 practitioners from various mental-health disciplines, using mind maps to represent the hierarchical relationships of data and concepts. Results: Strong consensus between experts meant their knowledge could be integrated into a single hierarchical structure for each risk. This revealed contrasting emphases between data and concepts underpinning risks, including: reflection and forethought for suicide; motivation for self-harm; situation and context for harm to others; and current presentation for self-neglect. Conclusions: Analysis of experts’ risk-assessment knowledge identified influential cues and their relationships to risks. It can inform development of valid risk-screening decision support systems that combine actuarial evidence with clinical expertise.

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The effect of organically modified clay on the morphology, rheology and mechanical properties of high-density polyethylene (HDPE) and polyamide 6 (PA6) blends (HDPE/PA6 = 75/25 parts) is studied. Virgin and filled blends were prepared by melt compounding the constituents using a twin-screw extruder. The influence of the organoclay on the morphology of the hybrid was deeply investigated by means of wide-angle X-ray diffractometry, transmission and scanning electron microscopies and quantitative extraction experiments. It has been found that the organoclay exclusively places inside the more hydrophilic polyamide phase during the melt compounding. The extrusion process promotes the formation of highly elongated and separated organoclay-rich PA6 domains. Despite its low volume fraction, the filled minor phase eventually merges once the extruded pellets are melted again, giving rise to a co-continuous microstructure. Remarkably, such a morphology persists for long time in the melt state. A possible compatibilizing action related to the organoclay has been investigated by comparing the morphology of the hybrid blend with that of a blend compatibilized using an ethylene–acrylic acid (EAA) copolymer as a compatibilizer precursor. The former remains phase separated, indicating that the filler does not promote the enhancement of the interfacial adhesion. The macroscopic properties of the hybrid blend were interpreted in the light of its morphology. The melt state dynamics of the materials were probed by means of linear viscoelastic measurements. Many peculiar rheological features of polymer-layered silicate nanocomposites based on single polymer matrix were detected for the hybrid blend. The results have been interpreted proposing the existence of two distinct populations of dynamical species: HDPE not interacting with the filler, and a slower species, constituted by the organoclay-rich polyamide phase, which slackened dynamics stabilize the morphology in the melt state. In the solid state, both the reinforcement effect of the filler and the co-continuous microstructure promote the enhancement of the tensile modulus. Our results demonstrate that adding nanoparticles to polymer blends allows tailoring the final properties of the hybrid, potentially leading to high-performance materials which combine the advantages of polymer blends and the merits of polymer nanocomposites.

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We have evaluated the cytotoxicity of a series of novel anti-tubercular 2-pyridyl carboxamidrazones through incubation with human mononuclear leucocytes (MNL), with and without a rat microsomal metabolising system. Isoniazid (INH), the closest structurally related agent, was used as a positive control. Incubation of the 3-benzyloxy-benzylidene, dimethylpropyl-benzylidene and 4-phenyl-benzylidene with MNL showed no significant toxicity in comparison with either INH or DMSO vehicle control. However, the 4-N,N-dimethylamino-1-naphthylidene derivative exerted more than sevenfold greater toxicity compared with INH, while the 4-N,N-dimethylamino-1-naphthylidene, 2-benzyloxy-3-methoxy-benzylidene, 2-t-butylthio-benzylidene and 4-i-propyl-benzylidene derivatives showed toxicity which ranged from five to fourfold that of INH. In the presence of either rat microsomes with or without NADPH, the 3-benzyloxy-benzylidene, dimethylpropyl-benzylidene and 4-phenyl-benzylidene derivatives showed no metabolically-mediated cytotoxicity. The latter two derivatives showed a combination of low toxicity and considerable efficacy against Mycobacteria tuberculosis in vitro and show promise for future development. © 2001 Elsevier Science B.V.