913 research outputs found
X-ray polarization in relativistic jets
No full textWe investigate the polarization properties of Comptonized X-rays from relativistic jets in active galactic nuclei (AGN) using Monte Carlo simulations. We consider three scenarios commonly proposed for the observed X-ray emission in AGN: Compton scattering of blackbody photons emitted from an accretion disc; scattering of cosmic microwave background (CMB) photons and self-Comptonization of intrinsically polarized synchrotron photons emitted by jet electrons. Our simulations show that for Comptonization of disc and CMB photons, the degree of polarization of the scattered photons increases with the viewing inclination angle with respect to the jet axis. In both cases, the maximum linear polarization is ≈20 per cent. In the case of synchrotron self-Comptonization (SSC), we find that the resulting X-ray polarization depends strongly on the seed synchrotron photon injection site, with typical fractional polarizations P≈ 10–20 per cent when synchrotron emission is localized near the jet base, while P≈ 20–70 per cent for the case of uniform emission throughout the jet. These results indicate that X-ray polarimetry may be capable of providing unique clues to identify the location of particle acceleration sites in relativistic jets. In particular, if synchrotron photons are emitted quasi-uniformly throughout a jet, then the observed degree of X-ray polarization may be sufficiently different for each of the competing X-ray emission mechanisms (synchrotron, SSC or external Comptonization) to determine which is the dominant process. However, X-ray polarimetry alone is unlikely to be able to distinguish between disc and CMB Comptonization
O estilo cinematográfico de Xavier Dolan
No full textEste trabalho se propõe a analisar o estilo cinematográfico de Xavier Dolan, a partir dos cinco primeiros longas-metragens do diretor: Eu Matei Minha Mãe (2009), Amores Imaginários (2010), Laurence Para Sempre (2012), Tom na Fazenda (2013) e Mommy (2014). A pesquisa tem como objetivo analisar o estilo de Dolan a partir da compreensão das técnicas cinematográficas utilizadas pelo diretor. Pretende-se também examinar como o cineasta cria padrões estilísticos através dos elementos visuais em seus filmes. A pesquisa busca ainda verificar de que forma Dolan, ao exercer diversos papéis na realização de seus filmes, contribui para a construção de um estilo autoral. O trabalho tem como principal referencial teórico o livro A arte do cinema: Uma introdução (2013), de David Bordwell e Kristin Thompson. Assim, a pesquisa se encontra dividida em três capítulos. No primeiro, são feitas contextualizações sobre forma fílmica e estilo cinematográfico, modos de produção cinematográfica, funções do diretor e seu trabalho como autor, além de apresentar o cineasta e os filmes que serão analisados. Os conceitos sobre forma e estilo são úteis para compreender as técnicas cinematográficas, enquanto que examinar os modelos de produção no cinema e o trabalho do diretor permite um melhor entendimento das escolhas técnicas. Já as informações sobre o diretor e os filmes são fundamentais para analisar o estilo de Dolan. No segundo, são abordadas as técnicas relacionadas à imagem fotográfica, divididas em quatro categorias: iluminação, amplitude tonal, velocidade do movimento e perspectiva. Ao mesmo tempo, são apresentadas as análises do uso das técnicas nos filmes. No terceiro capítulo, são apresentadas técnicas cinematográficas de enquadramento – dimensões e formas do quadro, ângulo, nível, altura e distância do enquadramento, e quadro móvel – e as respectivas análises. Foram selecionadas para as análises as técnicas proeminentes usadas pelo diretor, considerando aquelas que são recorrentes ou que diferenciam o trabalho do diretor dos demais cineastas.This study aims to analyze the film style of Xavier Dolan, as expressed in his five first films: J'ai tué ma mère (2009), Les Amours Imaginaires (2010), Laurence Anyways (2012), Tom à la Ferme (2013) and Mommy (2014). The research aims to analyze the style of Dolan from understanding of film techniques used by the director. This study also intended to examine how the filmmaker creates stylistic standards through visual elements in his films. The research also seeks to see how Dolan contributes to the construction of an authorial style by exercising various roles in the realization of his movies. The main theoretical reference of this study is the book Film art: An introduction (2013), written by David Bordwell and Kristin Thompson. The research is divided into three chapters. Firstly, it is made contextualization of film form and film style, film production modes, director’s roles and work as an author, as well as presenting the filmmaker and the movies. The concepts of form and style are useful to understand the film techniques, while examining the film production models and the director's work allows a better understanding of the technical choices. The information about the director and the movies are fundamental to analyze the style of Dolan. The second chapter presents the techniques related to the photographic image, divided into four categories: lighting, tonal range, speed of movement and perspective. At the same time, the analyses of the use of these techniques in the films are presented. The third chapter presents film techniques framing – dimensions and frame shapes, angle, level, height and distance of the frame and mobile frame – and analyses. For the analyses, the prominent techniques used by the director were selected considering those that are recurrent or that differentiate the work of the director of other filmmakers
Neural correlates of processing valence and arousal in affective words
No full textPsychological frameworks conceptualize emotion along 2 dimensions, "valence" and "arousal." Arousal invokes a single axis of intensity increasing from neutral to maximally arousing. Valence can be described variously as a bipolar continuum, as independent positive and negative dimensions, or as hedonic value (distance from neutral). In this study, we used functional magnetic resonance imaging to characterize neural activity correlating with arousal and with distinct models of valence during presentation of affective word stimuli. Our results extend observations in the chemosensory domain suggesting a double dissociation in which subregions of orbitofrontal cortex process valence, whereas amygdala preferentially processes arousal. In addition, our data support the physiological validity of descriptions of valence along independent axes or as absolute distance from neutral but fail to support the validity of descriptions of valence along a bipolar continuum
Mechanisms of top-down facilitation in perception of visual objects studied by fMRI
No full textPrior knowledge regarding the possible identity of an object facilitates its recognition from a degraded visual input, though the underlying mechanisms are unclear. Previous work implicated ventral visual cortex but did not disambiguate whether activity-changes in these regions are causal to or merely reflect an effect of facilitated recognition. We used functional magnetic resonance imaging to study top-down influences on processing of gradually revealed objects, by preceding each object with a name that was congruent or incongruent with the object. Congruently primed objects were recognized earlier than incongruently primed, and this was paralleled by shifts in activation profiles for ventral visual, parietal, and prefrontal cortices. Prior to recognition, defined on a trial-by-trial basis, activity in ventral visual cortex rose gradually but equivalently for congruently and incongruently primed objects. In contrast, prerecognition activity was greater with congruent priming in lateral parietal, retrosplenial, and lateral prefrontal cortices, whereas functional coupling between parietal and ventral visual (and also left lateral prefrontal and parietal) cortices was enhanced in the same context. Thus, when controlling for recognition point and stimulus information, activity in ventral visual cortex mirrors recognition success, independent of condition. Facilitation by top-down cues involves lateral parietal cortex interacting with ventral visual areas, potentially explaining why parietal lesions can lead to deficits in recognizing degraded objects even in the context of top-down knowledge
La postproducción en el cine de Xavier Dolan
No full textEn la presente memoria se desarrolla una investigación que constituye el Trabajo final de
Máster en Postproducción Digital de la Universitat Politècnica de València. En él se
pretende realizar un análisis de la filmografía completa del director Xavier Dolan, para ver
el papel que tiene la postproducción en su cine y cómo ésta es tan importante en la
narración.
Xavier Dolan es un director de cine canadiense nacido en 1989. Sus películas se
enmarcan dentro del cine independiente, ya que se realizan al margen de los circuitos
comerciales y de producción habituales. En ellas, tiene un papel preponderante,
realizando otras funciones, como guionista, productor o actor, por lo que se le considera
un director que realiza cine de autor. En este tipo de cine, el autor es normalmente
identificable por algunos rasgos típicos en su obra. Estos son los que trataremos de
analizar en este trabajo, centrándonos principalmente en los rasgos relacionados con la
postproducción.
Para ello, analizaremos los diferentes mecanismos empleados por este director en sus
películas, con el fin de contemplar cómo la postproducción influye en la narración y cómo
es usada para provocar una serie de emociones en el espectador. También veremos
cómo la postproducción influye en la construcción de su particular estilo narrativo.A research for the final thesis of the Master Degree on Digital Postproduction at the
Universitat Politècncia de Valencia is developed in the present paper. The aim was to
analyse the complete filmography of the director Xavier Dolan, in order to explore the role
that postproduction plays in his cinema and its importance in the narrative.
Xavier Dolan is a Canadian cinema director born in 1989. His movies are framed within the
independent cinema, outside the commercial circuits and usual production processes.
Directing the movies is his prevailing role, although he also performs other functions as
scriptwriter, producer, or actor, for it is considered as a experimental films director. In this
type of cinema, the author is normally identifiable for some unique traits of his work. The
goal of the present study is to analyse these traits, focusing mainly in the postproduction
related ones.
For that, we will analyse the different mechanisms used by this director in his films, as a
way to examine how the postproduction influences the narrative and how it is used to
cause a series of emotions in the audience. We will also study how postproduction
influences the construction of his personal narrative style.Escobar Picazo, A. (2016). La postproducción en el cine de Xavier Dolan. Universitat Politècnica de València. https://riunet.upv.es/handle/10251/74190TFG
A Clinician's Survival Guide to Leadership and Management on the Ward
No full textWhen you become a ward or unit manager or allied health professionals team leader, your responsibilities change and you need a very different set of skills compared with your previous roles. You are now required to manage a team of staff with a set budget and are responsible for maintaining an environment in which people can work together efficiently and effectively. This new fourth edition of the Survival Guide to Leadership and Management on the Ward welcomes AHP Krishna Gohil to the author team of nurses Brian Dolan and Amy Lochtie, and thereby extends its guidance on these crucial skills to both nurses and allied health professionals
Dopamine restores reward prediction errors in old age
No full textSenescence affects the ability to utilize information about the likelihood of rewards for optimal decision-making. Using functional magnetic resonance imaging in humans, we found that healthy older adults had an abnormal signature of expected value, resulting in an incomplete reward prediction error (RPE) signal in the nucleus accumbens, a brain region that receives rich input projections from substantia nigra/ventral tegmental area (SN/VTA) dopaminergic neurons. Structural connectivity between SN/VTA and striatum, measured by diffusion tensor imaging, was tightly coupled to inter-individual differences in the expression of this expected reward value signal. The dopamine precursor levodopa (L-DOPA) increased the task-based learning rate and task performance in some older adults to the level of young adults. This drug effect was linked to restoration of a canonical neural RPE. Our results identify a neurochemical signature underlying abnormal reward processing in older adults and indicate that this can be modulated by L-DOPA
Betwixt fast and slow: Integrating model-free and model-based decision-making
No full textBehavioural and neural evidence reveals a retrospective, model-free or habitual pro- cess that caches returns previously garnered from available choices, and a prospec- tive, model-based or goal-directed one that putatively relies on mental simulation of the environment. There is much current interest in understanding how these faster and slower systems are integrated to take advantage of the beneficial computational properties of each. I will discuss a recent study looking theoretically and empirically at the incorporation of model-free values into model-based calculations. This is joint work with Mehdi Keramati, Peter Smittenaar and Ray Dolan
The Imaging X-Ray Polarimetry Explorer (IXPE): technical overview IV
No full textScheduled to launch in late 2021 the Imaging X-ray Polarimetry Explorer (IXPE) is a Small Explorer Mission designed to open up a new window of investigation -- X-ray polarimetry. The IXPE observatory features 3 identical telescope each consisting of a mirror module assembly with a polarization-sensitive imaging x-ray detector at its focus. An extending beam, deployed on orbit provides the necessary 4 m focal length. The payload sits atop a 3-axis stabilized spacecraft which among other things provides power, attitude determination and control, commanding, and telemetry to the ground. During its 2-year baseline mission, IXPE will conduct precise polarimetry for samples of multiple categories of x-ray sources, with follow-on observations of selected targets. IXPE is a partnership between NASA and the Italian Space Agency (ASI)
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