52,293 research outputs found
Signatures of excitonic dark states in the time-resolved coherent response of a quantum well microcavity
No full textWe study the coherent time-resolved response of a semiconductor microcavity excited by an ultrashort light pulse. The cavity contains embedded quantum wells and quantum well excitons an strongly coupled to cavity photons. Two experimental situations are examined. We describe a linear regime when the exciting light pulse is weak. Further, a low-temperature pump-and-probe experiment in a nonlinear regime is analyzed, with a cw pump beam circularly polarized opposite to a weak ultrashort probe pulse in conditions yielding a bipolariton-mediated optical Stark effect. In both cases we examine the response of a single quantum well and contrast it with that of several quantum wells. In the latter case light is coupled only to a symmetric linear combination (bright exciton) of excitonic states in individual quantum wells. We find distinctive fingerprints of other linear combinations of exciton states (dark excitons). In the linear regime, in addition to a pattern of Rabi oscillations between the two polariton states, additional beating frequencies appear, related to dark states. In the nonlinear case, the bipolariton formalism outlined by Ivanov et al. [Phys. Rev. B 52, 11 017 (1995)] allows one to deduce a similar additional beating frequency and a splitting of bipolariton frequencies related to their dark or bright state character. This work identifies the effect of the microcavity parameters on its coherent response and determines the experimental conditions in which the influence of dark states may be observed
Hyperspectral imaging of the early embryo: Can it detect chromosome abnormalities and predict IVF success?
Full text linkDespite its wide-spread use, the success rate of assisted reproductive technologies including in vitro fertilization is less than 20%. Most human embryos are mosaic for chromosome abnormalities: containing cells that are euploid (normal) and aneuploid (incorrect number of chromosomes). Currently, a cell biopsy is used in IVF clinics to diagnose aneuploidy in the embryo but this does not provide a diagnosis of how many cells are aneuploid in the entire embryo. Hence, the development of a non-invasive tool to determine the proportion of aneuploid cells would likely improve IVF success. Aneuploidy in human embryos leads to altered metabolism. The co-factors utilized in cellular metabolism are autofluorescent and can be used to predict the metabolic state of cells. Here we used hyperspectral imaging to noninvasively assess intracellular fluorophores and thus metabolism. In this study, we utilized a powerful model of embryo aneuploidy where we generate mouse embryos with differing ratios of euploid:aneuploid cells. We also used primary human fibroblast cells with known aneuploidies to make comparison with euploid cells. Hyperspectral imaging of 1:3 chimeric embryos showed a distinct spectral profile compare to the control/normal embryos. The abundance of FAD in the inner cell mass (cells that form the fetus) of euploid and aneuploid blastocysts was strikingly different. For human cell lines, we were able to clearly distinguish between euploid and aneuploid with different karyotypes. These data show hyperspectral imaging is able to distinguish cells based on their ploidy status making it a promising tool in assessing embryo mosaicism
O foco narrativo na ficção contemporânea : uma leitura de Author, Author, de David Lodge
Full text linkOrientador : Prof. Dr. Caetano Waldrigues GalindoAutor não autorizou a divulgação do arquivo digitalDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Humanas, Letras e Artes, Programa de Pós-Graduação em Letras. Defesa: Curitiba, 26/06/2013Bibliografia: fls. 158-161Área de concentração: Estudos LiteráriosResumo: O propósito deste trabalho é refletir sobre a construção do foco narrativo em Author, Author (2004), de David Lodge, romance biográfico sobre o escritor Henry James (1843-1916). O narrador não se limita a situar o leitor na narrativa: o seu posicionamento em relação aos aspectos factuais da vida e do percurso literário do romancista norte-americano desempenha papel fundamental na discussão das estratégias narrativas da prosa de ficção de James. Na construção ficcional do malogro na noite de estreia de Guy Domville, em Londres, em 1895, por exemplo, é possível perceber a bipartição desse narrador, capaz de contar e mostrar dois episódios que se passam em dois lugares diferentes, simultaneamente. Em outros momentos do romance, a voz autoral embaralha-se com a voz do sujeito da enunciação a tal ponto, que o leitor menos atento encontra certa dificuldade para colocar ordem nos discursos. O abandono gradual da prosa de ficção em busca de uma identidade como dramaturgo, a falta de êxito na dramaturgia, a lenta recuperação psicológica, a retomada da prosa de ficção e o resultado insatisfatório da revisão e escrita de prefácios para as suas obras, para compor The novels and tales of Henry James:The New York Edition (1905), são alguns dos desdobramentos da trajetória de James, discutidos em Author, Author.Abstract: The purpose of this dissertation is to think over the construction process of narrative focus in Author, Author (2004), by David Lodge, a biographical novel about the writer Henry James (1843-1916). The narrator does not limit himself to guiding the reader through the narrative; rather, his attitude towards factual aspects of the life and literary course of the North-American novelist seems to play a fundamental role in the novel. In the fictional construction of the débâcle of "Guy Domville", in London, 1895 for instance it is possible to distinguish the narrator's bipartition, in order to tell and show two different episodes which happen in two different places, simultaneously. In other moments, the authorial voice blends with that of the subject of the enunciation to such a degree that the less attentive reader may not be capable of organizing the discourse, in a first moment. James' gradual movement away from prose fiction so as to find his playwright identity; the lack of success as a playwright; his subsequent slow psychological recovery; the return to prose fiction; and, finally, the weak result of writing and revising prefaces to his literary works in order to put together The Novels and Tales of Henry James: The New York Edition (1905), are some of the most conspicuous events in James' trajectory discussed in Author, Author
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Método e teoria em Ludwig Von Mises
Full text linkOrientador: José Guilherme Silva VieiraMonografia(Graduação) - Universidade Federal do Paraná,Setor de Ciências Sociais Aplicadas, Curso de Ciências EconômicasResumo: Analisam-se os escritos metodológicos e econômicos de Ludwig von Mises, autor por quem tem crescido o interesse no Brasil. Boa parte da obra do economista austríaco é dedicada a justificar o método, fundado em sua teoria da ação humana, a Praxeologia. No presente trabalho, procura-se saber se o autor efetivamente fez uso de tal método. Para entender o que a Praxeologia representava para Mises, faz-se uma pequena revisão histórica das discussões metodológicas em voga no tempo de Mises, além de uma comparação entre o Historicismo, o Positivismo e a Praxeologia. A análise segue com o levantamento de algumas das críticas sofridas pela Praxeologia e das defesas apresentadas por Mises. É argumentado que alguns dos seguidores, na tentativa de validar o método praxeológico, perverteram a intenção original que Mises tinha ao criar um método apriorístico. Alguns dos limites desse método se refletem na teoria monetária e por isso são estudados mais a fundoAbstract: Ludwig von Mises’, an author for whom the interest has rised in Brazil, methodological and economic works are analysed. A great share of the Austrian economist’s work was dedicated to justify his method, based on his theory of human action, Praxeology. The present work investigates if the author actually used his that method. A small historical review of the methodological debate in Mises’s time and a comparison between Historicism, Positivism and Praxeology are made in order to properly understand what Praxeology meant for Mises. The analysis follows with some of the critiques made against Praxeology and the answers Mises had for them. It’s shown that some of the attempts of Mises’ heirs to defend Praxeology perverted his original intention with the a priori method. Some of the limits of this method are analysed more carefully for they have implications on monetary theor
In vivo quantitative visualization of hypochlorous acid in the liver using a novel selective two-photon fluorescent probe
No full textHypochlorous acid (HOCl) plays a vital role in physiological events and diseases. During hepatic ischemia-reperfusion (I/R) injury, HOCl is generated by neutrophils and diffuses into hepatocytes, causing oxidant stress-mediated injury. Although many probes have been developed to detect HOCl, most were difficult to be distinguished from endogenous fluorophores in intravital imaging and only can be employed under one-photon microscopy. A novel iridium(III) complex-based ferrocene dual-signaling chemosensor (Ir-Fc) was designed and synthesized. Ir-Fc exhibited a strong positive fluorescent response only in the presence of HOCl, whereas negligible fluorescent signals were observed upon the additions of other reactive oxygen/nitrogen species and metal ions. There was a good linear relationship between probe responsive fluorescent intensity and HOCl concentration. Ir-Fc was then intravenously injected into BALB/c mice at the final concentration of 50 μM and the mouse livers were imaged using multiphoton microscopy (MPM). In the I/R liver, reduced autofluorescence was detected by MPM, indicating the hepatocyte necrosis. Remarkable enhancement of red fluorescence was observed in hepatocytes with decreased autofluorescence, indicating the reaction of Ir-Fc with endogenous HOCl molecules. The cellular concentration of HOCl was first calculated based on the intensity of MPM images. No obvious toxic effects were observed in histological examination of major organs after Ir-Fc injection. In summary, Ir-Fc has low cytotoxicity, high specificity to HOCl, and rapid "off-on" fluorescence. It is suitable for dynamic quantitatively monitoring HOCl generation using MPM at the cellular level. This technique can be readily extended to examination of liver diseases and injury
Computational modeling of a novel liquid crystal-based optrode
No full text© 2016 SPIE.Multielectrode arrays are a powerful tool for recording biopotentials, however they are limited by issues related to wiring complexity and channel-count. We present a novel concept for a liquid crystal-based optical electrode (optrode) that does not require the electrical circuitry associated with reading and amplifying each channel, thus providing superior spatial resolution and signal-to-noise ratio. Through computational modeling, we show that it is possible to accurately image biopotentials by coupling them to the electrodes of a LC cell and measuring their re ectance under parallel polarisers
O passado vive em mim : a consciência histórica na produção de Valêncio Xavier (Década de 1970-2000)
Full text linkOrientador : Prof. Dr. Renato Lopes LeiteCoorientadora : Profa. Dra. Rosane KaminskiDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Humanas, Letras e Artes, Programa de Pós-Graduação em História. Defesa: Curitiba, 28/02/2012Bibliografia: fls. 106-117Resumo: De que maneira a consciência histórica pode estar presente em distintas formas de expressão cultural? Esta questão norteia a pesquisa em que analiso a produção multifacetada de Valêncio Xavier (1933-2008). Buscando discutir como o autor construía sentido para suas obras, exploro o conjunto de sua produção relacionando-o com sua atuação socioprofissional, e investigando como a consciência histórica, independente do suporte utilizado por Xavier, permeia as obras. Considero que a consciência histórica está presente nas distintas formas de atuação desenvolvidas por Xavier no período abordado, entre as décadas de 1970 e 2000, seja em seus ensaios, em seu trabalho dirigindo instituições públicas, em seus livros ficcionais, e em seus audiovisuais. Além disso, defendo que o autor construiu uma relação identitária ligada ao Paraná, sobretudo à Curitiba, com sua produção cultural.Abstract: How historical consciousness can be present in distinct forms of cultural expression? This question guides the research in that I analyze the multifaceted Valêncio Xavier's production (1933-2008). Trying to discuss how the author constructed meaning in his works, I explore the set of his production, relating it to his business activities, and investigating how historical consciousness, regardless the support used by Xavier, permeates the works. I consider that the historical consciousness is present in different forms of action developed by Xavier in period analysed, between the 1970's and 2000, in his essays, in his work directing public institutions, in his fictional books, and in his audiovisuals. Moreover, I argue that the author built a relationship of identity linked to the Paraná, especially to the Curitiba, with his cultural productio
Light-triggered liposomal cargo delivery platform incorporating photosensitizers and gold nanoparticles for enhanced singlet oxygen generation and increased cytotoxicity
Full text linkZofia Kautzka, Sandhya Clement, Ewa M Goldys, Wei Deng Centre of Excellence for Nanoscale BioPhotonics, Macquarie University, North Ryde, Sydney, NSW, Australia Abstract: We developed light-triggered liposomes incorporating 3–5 nm hydrophobic gold nanoparticles and Rose Bengal (RB), a well-known photosensitizer used for photodynamic therapy. Singlet oxygen generated by these liposomes with 532 nm light illumination was characterized for varying the molar ratio of lipids and gold nanoparticles while keeping the amount of RB constant. Gold nanoparticles were found to enhance the singlet oxygen generation rate, with a maximum enhancement factor of 1.75 obtained for the molar ratio of hydrogenated soy l-α-phosphatidylcholine:1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(hexanoylamine):gold of 57:5:17 compared with liposomes loaded with RB alone. The experimental results could be explained by the local electric field enhancement caused by gold nanoparticles. We further assessed cellular cytotoxicity of gold-loaded liposomes by encapsulating an antitumor drug, doxorubicin (Dox); such Dox-loaded liposomes were applied to human colorectal cancer cells (HCT116) and exposed to light. Gold-loaded liposomes containing RB and Dox where Dox release was triggered by light were found to exhibit higher cytotoxicity compared with the liposomes loaded with RB and Dox alone. Our results indicate that gold-loaded liposomes incorporating photosensitizers may serve as improved agents in photodynamic therapy and chemotherapy. Keywords: liposomes, Rose Bengal, gold nanoparticles, singlet oxygen generation, photodynamic therap
A idéia de beleza moral em Schiller
Full text linkOrientador: Prof. Dr.Vinicius de FigueiredoDissertaçao (mestrado) - Universidade Federal do Paraná, Setor de Ciencias Humanas, Letras e Artes, Programa de Pós-Graduaçao em Filosofia. Defesa: Curitiba,20/09/2010Bibliografia: fls. 117-120Área de concentraçao: História da filosofia moderna e contemporâneaResumo: O objetivo geral dessa dissertação consistiu em chamar a atenção e mostrar a importância que o ensaio Sobre Graça e Dignidade (Über Anmut und Würde), publicado em 1793, possui dentro do pensamento estético de Friedrich von Schiller (1759-1805). Partindo da hipótese geral segundo a qual haveria uma centralidade da idéia de beleza moral no pensamento de Schiller (expressa na figura da Bela Alma (die schöne Seele) e no conceito de Graça (Anmut)), o ensaio Sobre Graça e Dignidade representaria o primeiro grande esforço do autor em reunir os elementos que seriam fundamentais em seu conhecido projeto de educação estética. Concentrei a investigação sobre o ensaio em dois principais momentos: primeiro, a relação de Schiller com a filosofia de Kant: procurei mostrar que a concepção schilleriana de beleza moral procurou operar uma ampliação – estética – do conceito de liberdade, herdado da filosofia kantiana, sem divergir, contudo, dos princípios fundamentais; segundo, a inspiração além-Kant: ainda que a problemática do ideal schilleriano de beleza moral só seja bem compreendida se for levado em conta a relação com a filosofia kantiana, Schiller não o concebeu a partir desse envolvimento – é um ideal que tem inspiração numa Grécia idealizada – helenismo característico de sua época, advindo em grande parte da obra de J. J. Winckelmann. Entremeio, tracei uma breve história do conceito de graça, procurando salientar as diversas formulações que esse conceito, tão importante para Schiller, evoca.Abstract: The real goal of this lecture was to call short view and importance the insight about the essay Grace and Dignity (Über Anmut und Würde), published in 1793, which is declared in Friedrich von Schiller esthetic thinking (1759-1805). Up to the general hypothesis according to it should have a centrality of beauty moral ideain Schiller thinking (expressed in Picture Beauty Soul, (die schöne Seele) and in concept of grace (Anmut)), the essay Grace and Dignity would express the first biggest effort of the author in unique all elements which would be available in his known projects of education esthetic. I focussed the insight investigation in two especial events: first, the relation of Schiller within Kant philosophy: I tried to show that Schillerian conception of Beauty and Moral graced only and extenced - esthetic – concept of Freedom, earned from Kant philosophy, even sneaking, as well, of fundamentals begining; second, the inspiration worth Kant: even if the problematic of Schillirian ideal of Beauty and Moral would just be understood if we considerate Kant philosophy, Schiller didn't get him allowed him since that conception rollment – its an ideal that has inspiration in an idealized Greece – helenism characteristic of his term, became as well from J.J. Winckelmann. Among them, I figured out a shortly history of Grace concept, trying to especify so many formulations that the concept has, which it so important for Schiller, evoque
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