4,515 research outputs found
Synthèse sonochimique de nanomatériaux et sonocatalyse
No full textNational audienceLes traitements ultrasonores peuvent être réalisés dans une large gamme de conditions opératoires permettant ainsi de générer des effets physiques et chimiques dans des milieux aussi bien à température ambiante qu’en conditions hydrothermales.Grâce à ces spécificités, la sonochimie apparait comme une technique particulièrement intéressante pour la préparation de matériaux de nature chimique variée et permet la conception de voies de synthèses innovantes. Différents protocoles ont ainsi été développés au sein de notre laboratoire mettant notamment en œuvre la réduction sonochimique de métaux nobles mono ou bimétalliques sur des supports polymériques thermosensibles de taille contrôlée sans ajouts de réactifs. Ces matériaux ont ensuite été utilisés comme agents porogènes et vecteurs de la phase active pour la synthèse de catalyseurs supportés à porosité hiérarchique et à designs originaux [1-2]. Une autre approche que nous avons étudiée concerne l’élaboration de nanomatériaux de type cœur coquille Ti@TiO2 obtenus au cours d’un traitement sonohydrohtermal à 200 °C sous 13 bar et irradiation ultrasonore simultanée à 20 kHz. Les propriétés optiques spécifiques de ces catalyseurs ont ensuite été exploitées pour la génération d’hydrogène au cours de l’irradiation, dans le visible et le proche infrarouge, de solutions aqueuses en présence de composés organiques sacrificiels [3].L’utilisation du phénomène de cavitation acoustique ne se limite cependant pas à la synthèse de matériaux et permet également d’envisager des applications en sonocatalyse et en particulier pour les réactions d’oxydation et de dégradation des polluants organiques. En effet, la génération in situ d’espèces oxydantes réactives et peu sélectives comme les radicaux OH·, permet de considérer la sonochimie comme une technique d’oxydation avancée pour la décontamination des effluents aqueux. Cependant, les quantités de radicaux formés restent généralement faibles, de l’ordre de la µmol.min-1, et ne permettent de traiter que des effluents faiblement pollués. Ainsi, différentes études au sein de notre laboratoire ont mis en évidence que le phénomène de cavitation acoustique permettait d’activer certains catalyseurs comme Co3O4/TiO2 pour la défonctionalisation de l’EDTA ou bien d’augmenter les performances catalytique de Pt/TiO2 au cours de la minéralisation des acides carboxyliques à 40 °C en présence d’oxygène sous irradiation ultrasonore à haute fréquence [4-5].[1]. Salazar A. F. S., Chave T., Ayral A., Nikitenko S. I., Hulea V., Kooyman P. J., Tichelaar F. D., Perathoner S. et Lacroix-Desmazes P., 2016, Micropor. Mesopor. Mat., 234, 207-214.[2]. Salazar A. F. S., Chave T., Ayral A., Nikitenko S. I., Hulea V., Kooyman P. J., Tichelaar F. D., Perathoner S. et Lacroix-Desmazes P., 2018, Micropor. Mesopor. Mat., 256, 227-234.[3]. Nikitenko S.I., Chave T., Cau C., Brau H-P., Flaud V., 2015, ACS Catal., 5, 4790-4795.[4]. Chave T., Navarro N. M., Pochon P., Perkas N., Gedanken A. et Nikitenko S. I., 2015, Catal. Today, 241, 55-62[5]. L. Parizot, T. Chave, M.E. Galvez, H. Dutilleul, P. Da Costa et S. I. Nikitenko, 2019, Appl. Catal. B, 241, 570-57
Synthèse sonochimique de nanomatériaux et sonocatalyse
No full textNational audienceLes traitements ultrasonores peuvent être réalisés dans une large gamme de conditions opératoires permettant ainsi de générer des effets physiques et chimiques dans des milieux aussi bien à température ambiante qu’en conditions hydrothermales.Grâce à ces spécificités, la sonochimie apparait comme une technique particulièrement intéressante pour la préparation de matériaux de nature chimique variée et permet la conception de voies de synthèses innovantes. Différents protocoles ont ainsi été développés au sein de notre laboratoire mettant notamment en œuvre la réduction sonochimique de métaux nobles mono ou bimétalliques sur des supports polymériques thermosensibles de taille contrôlée sans ajouts de réactifs. Ces matériaux ont ensuite été utilisés comme agents porogènes et vecteurs de la phase active pour la synthèse de catalyseurs supportés à porosité hiérarchique et à designs originaux [1-2]. Une autre approche que nous avons étudiée concerne l’élaboration de nanomatériaux de type cœur coquille Ti@TiO2 obtenus au cours d’un traitement sonohydrohtermal à 200 °C sous 13 bar et irradiation ultrasonore simultanée à 20 kHz. Les propriétés optiques spécifiques de ces catalyseurs ont ensuite été exploitées pour la génération d’hydrogène au cours de l’irradiation, dans le visible et le proche infrarouge, de solutions aqueuses en présence de composés organiques sacrificiels [3].L’utilisation du phénomène de cavitation acoustique ne se limite cependant pas à la synthèse de matériaux et permet également d’envisager des applications en sonocatalyse et en particulier pour les réactions d’oxydation et de dégradation des polluants organiques. En effet, la génération in situ d’espèces oxydantes réactives et peu sélectives comme les radicaux OH·, permet de considérer la sonochimie comme une technique d’oxydation avancée pour la décontamination des effluents aqueux. Cependant, les quantités de radicaux formés restent généralement faibles, de l’ordre de la µmol.min-1, et ne permettent de traiter que des effluents faiblement pollués. Ainsi, différentes études au sein de notre laboratoire ont mis en évidence que le phénomène de cavitation acoustique permettait d’activer certains catalyseurs comme Co3O4/TiO2 pour la défonctionalisation de l’EDTA ou bien d’augmenter les performances catalytique de Pt/TiO2 au cours de la minéralisation des acides carboxyliques à 40 °C en présence d’oxygène sous irradiation ultrasonore à haute fréquence [4-5].[1]. Salazar A. F. S., Chave T., Ayral A., Nikitenko S. I., Hulea V., Kooyman P. J., Tichelaar F. D., Perathoner S. et Lacroix-Desmazes P., 2016, Micropor. Mesopor. Mat., 234, 207-214.[2]. Salazar A. F. S., Chave T., Ayral A., Nikitenko S. I., Hulea V., Kooyman P. J., Tichelaar F. D., Perathoner S. et Lacroix-Desmazes P., 2018, Micropor. Mesopor. Mat., 256, 227-234.[3]. Nikitenko S.I., Chave T., Cau C., Brau H-P., Flaud V., 2015, ACS Catal., 5, 4790-4795.[4]. Chave T., Navarro N. M., Pochon P., Perkas N., Gedanken A. et Nikitenko S. I., 2015, Catal. Today, 241, 55-62[5]. L. Parizot, T. Chave, M.E. Galvez, H. Dutilleul, P. Da Costa et S. I. Nikitenko, 2019, Appl. Catal. B, 241, 570-57
The influence of background diabetic retinopathy in the second eye on rates of progression of diabetic retinopathy between 2005 and 2010.
No full textPURPOSE: The Gloucestershire Diabetic Eye Screening Programme offers annual digital photographic screening for diabetic retinopathy to a countywide population of people with diabetes. This study was designed to investigate progression of diabetic retinopathy in this programme of the English NHS Diabetic Eye Screening Programme. METHODS: Mydriatic digital retinal photographs of people with diabetes screened on at least 2 occasions between 2005 and 2010 were graded and included in this study if the classification at first screening was no DR (R0), background DR in one (R1a) or both eyes (R1b). Times to detection of referable diabetic retinopathy (RDR) comprising maculopathy (M1), preproliferative (R2) or proliferative retinopathy (R3) were analysed using survival models. RESULTS: Data were available on 19 044 patients, 56% men, age at screening 66 (57-74) years (median, 25th, 75th centile). A total of 8.3% of those with R1a and 28.2% of those with R1b progressed to any RDR, hazard ratios 2.9 [2.5-3.3] and 11.3 [10.0-12.8]. Similarly 7.1% and 0.11% of those with R1a progressed to M1 and R3, hazard ratios 2.7 [2.3-3.2] and 1.6 [0.5-5.0], compared to 21.8% and 1.07% of those with R1b, hazard ratio 9.1 [7.8-10.4] and 15.0 [7.1-31.5]. CONCLUSIONS: The risk of progression is significantly higher for those with background DR in both eyes than those with background retinopathy in only one or in neither eye
Das memórias às veredas: Revista USP - letras, cenas e sons
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão. Programa de Pós-graduação em LiteraturaEsta tese tenta configurar o espaço ocupado pela literatura na Revista USP, partindo da reflexão que ali se realiza sobre a arte produzida nos anos 80 e 90. As criações recentes da música popular, do teatro e do cinema são submetidas a um balanço enquanto a literatura não recebe o mesmo tipo de abordagem crítica. Investigar as motivações e desdobramentos de tal postura por parte da revista é a principal proposição desta pesquisa, que busca desenvolver a seguinte hipótese: um vasto conjunto de ensaios publicados na Revista USP compõe um mosaico, no qual a reflexão acerca da literatura brasileira se configura através da constituição de um eixo monumental, formado por Memórias póstumas de Brás Cubas, de Machado de Assis e Grande sertão: veredas, de João Guimarães Rosa. Estas duas obras sustentam e demarcam os limites do cânone proposto pela revista, que posiciona a obra de Guimarães Rosa como última baliza do ciclo criativo da literatura brasileira. Entretanto, é possível perceber algumas sombras que conturbam o desenho nítido do referido eixo. A primeira delas é Grande sertão: veredas enquanto texto neobarroco e a segunda é uma antologia de poesia brasileira publicada na revista Universidad de México. This thesis tries to configure the space occupied by literature in Revista USP magazine, starting from the reflection about the art produced in the 80's and 90's. The popular music, the theater and the movies are submitted to an evaluation of their recent creations while the literature does not receive the same kind of critical approach. Investigating motivations and consequences of this attitude is the main proposition of this research, which intends to develop the following hypothesis: a great amount of texts published in Revista USP composes a mosaic, in which the reflection about Brazilian literature configures itself through the constitution of a monumental axle, formed by Memórias póstumas de Brás Cubas, written by Machado de Assis and Grande sertão: veredas, by João Guimarães Rosa. These books mark and support the limits of the canon proposed by the magazine, which considers Guimarães Rosa's narrative as the last sign of creativity in Brazilian literature. Although, it's possible to perceive some shadows that disturb the clearness of this axle. The first one is Grande sertão: veredas seen as a "neobarroco" text, and the second is an anthology of Brazilian poetry published at Universidad de México magazine
Retratos de um passado recente
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Literatura, Florianópolis, 2015.Esta tese procura investigar as razões e os desdobramentos da existência de dois periódicos culturais estudantis, Universitário (1974-1975) e O Acadêmico (1975-1982), que circularam no interior de Santa Catarina, na cidade de Blumenau, especificamente na Fundação Regional de Blumenau (FURB) durante os anos de 1970. A partir de relatos de memória advindos de um passado recente e construídos como narrativas do agora, obtém-se a configuração da história desses projetos. Assim, o objetivo deste estudo é conhecer a conjuntura histórica desse corpus e também analisar o discurso que nele se apresenta, sobretudo apontando sinais de crítica e resistência ao regime autoritário em Blumenau. Para tanto, foram indexadas 11 (onze) edições do jornal Universitário, incidindo, de forma predominante, a publicação de artigos-informes; em seguida, o espaço aparece ocupado pela literatura, em especial pela poesia. Por sua vez, nas 62 (sessenta e duas) edições de O Acadêmico, a poesia é o que toma o lugar de destaque. Analisar e conhecer criticamente esses jornais induz assim à ampliação da reflexão em torno da produção cultural na imprensa brasileira. É possível, então, perceber, por meio do estudo desses dois periódicos, retratos de uma produção esquecida e, por vezes, ?nada conhecida? na década de 1970. De um lado, reproduz-se a imagem do contexto sócio-político cultural em tempos de ditadura, principalmente em Blumenau; essa produção cultural aparece, então, como interesse da política dominante, e também como desejo dos estudantes universitários, especialmente da FURB, de se pronunciarem. Revela-se a partir daí uma relação de dominação e subordinação, chamada por Gramsci de hegemonia, notadamente marcada por manifestações de poder, de interesses entre os estudantes universitários e a ditadura. Por outro lado, a experiência com a linguagem poética assume um diálogo anacrônico, isto é, de conversa com a tradição. Esses poemas institucionais, vinculados à FURB, mostram-se como práticas criativas ou como atividade pedagógica por meio da qual os estudantes desenvolvem o seu potencial de criação escrita e, ainda aparecem como reflexo do contexto histórico-sócio-cultural dos anos 70. Assim, nesses retratos, mostra-se o desejo, principalmente por parte dos estudantes universitários da FURB, em ser oposição ao contexto autoritário em Blumenau nos tempos de silêncio forçado.Abstract : This thesis seeks to investigate the reasons and the developments meanings in two academic cultural periodicals, Universitário (1974-1975) and O Acadêmico (1975-1982), which circulated in the countryside of Santa Catarina, in the city of Blumenau, specifically at ?Fundação Regional de Blumenau (FURB)?, during the 70?s. From memory reports arising from a recent past and constructed as narratives of the now, the shaping of the story of these projects is obtained. Thus, the aim of this study is to know the historical context of this corpus, and also, to analyses the discourse it presents, especially pointing out signs of criticism and resistance to the authoritarian regime in Blumenau. For this purpose, 11 (eleven) editions of the newspaper Universitário were indexed, by focusing in a predominant way, the publication of articles/reports; thereafter, the space is occupied by literature, in particular by poetry. On its turn, in the 62 (sixty-two) editions of the O Acadêmico, the poetry is what takes a preeminent space. Critically analyzing and knowing these journals leads, thus, to the enlargement of the reflection on the cultural production in the Brazilian press. Then, it is possible to notice, through the study of these two periodicals, portraits of a forgotten production and, sometimes, "scarcely known", in the 70s. On one hand, the image of the socio-political and cultural context in times of dictatorship is reproduced, especially in Blumenau; this cultural production is shown, then, as the interest of the dominant political mainstream and, also, as the desire of the students from the university, especially those from FURB, to express themselves. From then on, a relationship of domination and subordination is revealed, defined by Gramsci as hegemony, notably characterized by demonstrations of power, of interests between the students from the university and the dictatorship. On the other hand, the experience with the poetic language assumes an anachronic dialogue, that is, a kind of conversation, with the tradition. These institutional poems, linked to FURB, are shown as creative practices, or as pedagogical activity, through the ones, students develop their potential for creation to point a socio-historical and cultural context and writing during the dictatorship. Thus, in these portraits, especially by the FURB students, is shown the desire of being opposition to the authoritarian context in Blumenau, during those days of forced silenc
Testing the metabolic theory of ecology
No full textThe metabolic theory of ecology (MTE) predicts the effects of body size and temperature on metabolism through considerations of vascular distribution networks and biochemical kinetics. MTE has also been extended to characterise processes from cellular to global levels. MTE has generated both enthusiasm and controversy across a broad range of research areas. However, most efforts that claim to validate or invalidate MTE have focused on testing predictions. We argue that critical evaluation of MTE also requires strong tests of both its theoretical foundations and simplifying assumptions. To this end, we synthesise available information and find that MTE's original derivations require additional assumptions to obtain the full scope of attendant predictions. Moreover, although some of MTE's simplifying assumptions are well supported by data, others are inconsistent with empirical tests and even more remain untested. Further, although many predictions are empirically supported on average, work remains to explain the often large variability in data. We suggest that greater effort be focused on evaluating MTE's underlying theory and simplifying assumptions to help delineate the scope of MTE, generate new theory and shed light on fundamental aspects of biological form and function
Bounded influence magnetotelluric response function estimation
No full textAuthor Posting. © Blackwell, 2004. This article is posted here by permission of Blackwell for personal use, not for redistribution. The definitive version was published in Geophysical Journal International 157 (2004): 988–1006, doi:10.1111/j.1365-246X.2004.02203.x.Robust magnetotelluric response function estimators are now in standard use in electromagnetic induction research. Properly devised and applied, these have the ability to reduce the influence of unusual data (outliers) in the response (electric field) variables, but are often not sensitive to exceptional predictor (magnetic field) data, which are termed leverage points. A bounded influence estimator is described which simultaneously limits the influence of both outliers and leverage points, and has proven to consistently yield more reliable magnetotelluric response function estimates than conventional robust approaches. The bounded influence estimator combines a standard robust M-estimator with leverage weighting based on the statistics of the hat matrix diagonal, which is a standard statistical measure of unusual predictors. Further extensions to magnetotelluric data analysis are proposed, including a generalization of the remote reference method which utilizes multiple sites instead of a single one and a two-stage bounded influence estimator which effectively removes correlated noise in the local electric and magnetic field variables using one or more uncontaminated remote references. These developments are illustrated using a variety of magnetotelluric data.This work was supported at WHOI by the Office of Basic Energy Sciences, US Department of Energy and by National Science Foundation grant EAR-0087699
On the electromagnetic fields produced by marine frequency domain controlled sources
No full textAuthor Posting. © The Author, 2009. This article is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Geophysical Journal International 179 (2009): 1429-1457, doi:10.1111/j.1365-246X.2009.04367.x.In recent years, marine controlled source electromagnetics (CSEM) has found increasing use in hydrocarbon exploration due to its ability to detect thin resistive zones beneath the seafloor. Although it must be recognized that the quantitative interpretation of marine CSEM data over petroleum-bearing formations will typically require 2-D surveys and 2-D or 3-D modelling, the use of the 1-D approximation is useful under some circumstances and provides considerable insight into the physics of marine CSEM. It is the purpose of this paper to thoroughly explore the 1-D solutions for all four fundamental source types—vertical and horizontal, electric and magnetic dipole (VED, HED, VMD and HMD)—using a set of canonical reservoir models that encompass brine to weak to strong hydrocarbon types. The paper introduces the formalism to solve the Maxwell equations for a 1-D structure in terms of independent and unique toroidal and poloidal magnetic modes that circumscribe the salient diffusion physics. Green's functions for the two modes from which solutions for arbitrary source current distributions can be constructed are derived and used to obtain the electromagnetic (EM) fields produced by finite VED, HED, VMD and HMD sources overlying an arbitrary 1-D electrical structure. Field behaviour is analysed using the Poynting vector that represents the time-averaged flow of energy through the structure and a polarization ellipse decomposition of the triaxial seafloor EM field that is a complete field description. The behaviour of the two EM modes using unimodal VED and VMD sources is presented. The paper closes by extending these results to the bimodal HED and HMD sources
Tempo das figuras: Agambem, Virno, Cacciari, Rella
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Literatura, Florianópolis, 2009Este trabalho tem como objetivo analisar quatro figuras da crítica italiana contemporânea que antagonizam e protagonizam o debate sobre estética e política: Giorgio Agamben, Paolo Virno, Massimo Cacciari e Franco Rella. A análise passa, principalmente, pelos materiais esparsos produzidos a partir dos anos 1970 até a entrada do novo século, a fim de observar a montagem das categorias que movimentam as articulações desses pensamentos. Categorias que, carregadas de tempo e de ética, permitem chegar à hipótese de que o pensar filosófico e o fazer poético, artístico e crítico operam de maneira polarmente conjugada na inoperância constituída entre as quatro figuras, de modo a perceber que: pela profanação, Agamben monta as imagens que transitam entre as diversas disciplinas do saber e a arte; pela ambivalência, Virno rearticula a conduta da esquerda, a partir de considerações marxinianas; pelo paradoxo do pensamento, Cacciari explicita filosofia estética e filosofia política; pela noção de figura, Rella passeia pelas imagens da modernidade. Diante das divergências e das semelhanças há algo que os toca: a tarefa dada ao tempo
The Biomass Mission: Objectives and Requirements
No full textThe Earth Explorer Biomass mission will provide the scientific community with accurate maps of tropical, temperate and boreal forest biomass, including height and disturbance patterns. This information is urgently needed to improve our understanding of the global carbon cycle and to reduce uncertainties in the calculation of carbon stocks and fluxes associated to the terrestrial biosphere. It is also crucial for approaches to managing climate, such as the UNFCCC initiative known as Reducing Emissions through Degradation and Deforestation (REDD+), aimed at climate change mitigation through conservation and better management of tropical forests The required measurements are forest biomass and forest height at resolution of 200 m, and detection of deforestation at 50 m. Global maps of biomass are required with accuracy of 20% (or l0 t ha-1 when above-ground biomass are less than 50 t ha-1). To achieve this Biomass will be implemented as a P-band SAR mission. It will exploit the unique sensitivity of P-band SAR together with advanced retrieval methods including polarimetric interferometry (Pol-InSAR) and SAR tomography to measure biomass, height and disturbances across the entire biomass range every 6 months. The mission will also support important secondary objectives, including sub-surface imaging in arid zones, production of a bare-earth DTM and ice applications
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