1000 resultados para Funcions de diverses variables complexes
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Collection : Les archives de la Révolution française ; 11.1a.477
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En el marc del procés de desenvolupament de l'Espai Europeu d¿Educació Superior, aquest article presenta una activitat d'aprenentatge innovadora, amb la que es pretén fomentar diverses competències afins a les directrius proposades, com són l'autoaprenentatge, el treball col·laboratiu, la cerca i anàlisi de documentació, l'autoavaluació i l'avaluació entre iguals, que es duu a terme en l'assignatura teòrica i pràctica Fotografia, optativa del grau de l'ensenyament de Belles Arts....
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La insolvència de l'herència o del causant ha estat afrontada amb tècniques diverses en tots els ordenaments jurídics. La Llei concursal (Llei 22/2003, de 9 de juliol, a partir d'ara, LCon) es refereix en alguns articles al que s'ha anomenat concurs de l'herència, la qual cosa no vol dir que solucioni, ni de bon tros, els problemes que sorgeixen de la insolvència. En aquest treball només intento identificar alguns dels problemes que la Llei concursal deixa sense resoldre i el que succeeix quan es posen en relació les normes concursals amb el Codi de successions i molt especialment, amb la institució del benefici d¿inventari, així com les regles de la LEC, ja complexes per elles mateixes. Aquest treball, per tant, s¿ha de considerar un working paper en sentit estricte: sempre resulta molt difícil iniciar una matèria en la qual la bibliografia és pràcticament inexistent.
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Dans certaines conditions pathologiques, telles que l'hypertension artérielle ou l'infarctus du myocarde, le coeur répond à une augmentation de la post-charge par des processus de remodelage aboutissant à une hypertrophie du ventricule gauche. L'hypertrophie cardiaque est caractérisée par une croissance hypertrophique des cardiomyocytes, ainsi que par une différenciation des fibroblastes en un phenotype présentant une capacité accrue de synthèse protéiques, nommés myofibroblastes. Ceci résulte en une accumulation excessive des constituants de la matrice extracellulaire, ou autrement dit fibrose. En raison de son effet délétère sur la contractilité du coeur, menant sur le long terme à une insuffisance cardiaque, de nombreux efforts ont été déployés, afin de définir les mécanismes moléculaires impliqués dans la réponse profibrotique. A ce jour, de nombreuses études indiquent que la petite GTPase RhoA pourrait être un médiateur important de la réponse profibrotique du myocarde. Cependant, les facteurs d'échanges impliqués dans la transduction de signaux profibrotiques, via la régulation de son activité au niveau des fibroblastes cardiaques, n'ont pas encore été identifiés. De précédentes études menées dans le laboratoire, ont identifiées une nouvelle protein d'ancrage de la PKA, exprimée majoritairement dans le coeur, nommée AKAP-Lbc. Il a été montré que cette protéine, en plus de sa fonction de protein d'ancrage, possédait une activité de facteur d'échange de nucléotide guanine (GEF) pour la petite GTPase RhoA. Au niveau des cardiomyocytes, il a été montré que l'AKAP-Lbc participe à une voie de signalisation pro-hypertrophique, incluant la sous-unité alpha de la protéine G hétérotrimerique G12 et RhoA. Chose intéressante, des observations antérieures à cette étude, indiquent que dans le coeur, l'AKAP-Lbc est également exprimée dans les fibroblastes. Cependant aucunes études n'a encore reporté de fonction pour ce facteur d'échange dans les fibroblastes cardiaques. Dans ce travail, les résultats obtenus indiquent que dans les fibroblastes cardiaques, I'activation de RhoA par l'AKAP-Lbc est impliquée dans la transmission de signaux profibrotiques, en aval des récépteurs à l'angiotensine II. En particulier, nous avons observé que la suppression de l'expression de l'AKAP-Lbc dans les fibroblastes ventriculaires de rat adultes, réduisait fortement Γ activation de Rho induite par l'angiotensine II, la déposition de collagène, la capacité migratoire des fibroblastes ainsi que leur différenciation en myofibroblastes. A notre connaissance, l'AKAP-Lbc est le premier RhoGEF identifié comme médiateur de la réponse profibrotique dans les fibroblastes cardiaques. - In pathological conditions such as chronic hypertension or myocardial infarction, the myocardium is subjected to various biomechanical and biochemical stresses, and undergoes an adverse ventricular remodelling process associated with cardiomyocytes hypertrophy and excess deposition of extracellular matrix proteins resulting in fibrosis. During the fibrotic response, cardiac fibroblasts differentiate into a more mobile and contractile phenotype termed myofibroblasts. These cells, possess a greater synthetic ability to produce ECM proteins and have been implicated in diseases with increased ECM deposition including cardiac fibrosis. Because fibrosis impairs myocardial contractility and is associated with the progression to heart failure, a major cause of lethality worldwide, many efforts have been made to define the molecular players involved in this process. During these last years, increasing evidence suggests a role for the small GTPase RhoA in mediating the fibrotic response in CFbs. However the identity of the exchange factors that modulate its activity and transduce fibrotic signals in CFbs is still unknown. Earlier work in our laboratory identified a novel PKA anchoring protein expressed in the heart termed AKAP-Lbc that has been shown to function as anchoring protein as well as a guanine nucleotide exchange factor (GEF) for the small GTPase RhoA. In response to several hypertrophic stimuli we have shown that RhoGEF activity of AKAP-Lbc mediated by Gan promotes the activation of a signaling pathway including RhoA, leading to cardiomyocytes hypertrophy. Within the heart, previous observations made in the laboratory indicated that AKAP-Lbc was also expressed in fibroblasts. However its role in cardiac fibroblasts remained to be determined. In the present study, we show that AKAP-Lbc is critical for activating RhoA and transducing profibrotic signals downstream of angiotensin II receptors in cardiac fibroblasts. In particular, our results indicate that suppression of AKAP-Lbc expression by infecting adult rat ventricular fibroblasts with lentiviruses encoding AKAP-Lbc specific short hairpin RNAs strongly reduces angiotensin II-induced RhoA activation, collagen deposition as well as cell migration and differentiation. These findings identify AKAP-Lbc as the first Rho-guanine nucleotide exchange factor involved in a profibrotic signalling pathway at the level of cardiac fibroblasts.
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Sadannan vaikutus vedenpinnan tasoon kohosuolla
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Un juego de asignación se define por una matriz A; donde cada fila representa un comprador y cada columna un vendedor. Si el comprador i se empareja a un vendedor j; el mercado produce aij unidades de utilidad. Estudiamos los juegos de asignación de Monge, es decir, aquellos juegos bilaterales de asignación en los cuales la matriz satisface la propiedad de Monge. Estas matrices pueden caracterizarse por el hecho de que en cualquier submatriz 2x2 un emparejamiento óptimo está situado en la diagonal principal. Para mercados cuadrados, describimos sus núcleos utilizando sólo la parte central tridiagonal de elementos de la matriz. Obtenemos una fórmula cerrada para el reparto óptimo de los compradores dentro del núcleo y para el reparto óptimo de los vendedores dentro del núcleo. Analizamos también los mercados no cuadrados reduciéndolos a matrices cuadradas apropiadas.
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[eng] In the context of cooperative TU-games, and given an order of players, we consider the problem of distributing the worth of the grand coalition as a sequentia decision problem. In each step of process, upper and lower bounds for the payoff of the players are required related to successive reduced games. Sequentially compatible payoffs are defined as those allocation vectors that meet these recursive bounds. The core of the game is reinterpreted as a set of sequentally compatible payoffs when the Davis-Maschler reduced game is considered (Th.1). Independently of the reduction, the core turns out to be the intersections of the family of the sets of sequentially compatible payoffs corresponding to the different possible orderings (Th.2), so it is in some sense order-independent. Finally, we analyze advantagenous properties for the first player
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Objective: To describe the methodology of Confirmatory Factor Analyis for categorical items and to apply this methodology to evaluate the factor structure and invariance of the WHO-Disability Assessment Schedule (WHODAS-II) questionnaire, developed by the World HealthOrganization.Methods: Data used for the analysis come from the European Study of Mental Disorders(ESEMeD), a cross-sectional interview to a representative sample of the general population of 6 european countries (n=8796). Respondents were administered a modified version of theWHODAS-II, that measures functional disability in the previous 30 days in 6 differentdimensions: Understanding and Communicating; Self-Care, Getting Around, Getting Along withOthers, Life Activities and Participation. The questionnaire includes two types of items: 22severity items (5 points likert) and 8 frequency items (continuous). An Exploratory factoranalysis (EFA) with promax rotation was conducted on a random 50% of the sample. Theremaining half of the sample was used to perform a Confirmatory Factor Analysis (CFA) inorder to compare three different models: (a) the model suggested by the results obtained in theEFA; (b) the theoretical model suggested by the WHO with 6 dimensions; (c) a reduced modelequivalent to model b where 4 of the frequency items are excluded. Moreover, a second orderfactor was also evaluated. Finally, a CFA with covariates was estimated in order to evaluatemeasurement invariance of the items between Mediterranean and non-mediterranean countries.Results: The solution that provided better results in the EFA was that containing 7 factors. Twoof the frequency items presented high factor loadings in the same factor, and one of thempresented factor loadings smaller than 0.3 with all the factors. With regard to the CFA, thereduced model (model c) presented the best goodness of fit results (CFI=0.992,TLI=0.996,RMSEA=0.024). The second order factor structure presented adequate goodness of fit (CFI=0.987,TLI=0.991, RMSEA=0.036). Measurement non-invariance was detected for one of the items of thequestionnaire (FD20 ¿ Embarrassment due to health problems).Conclusions: AFC confirmed the initial hypothesis about the factorial structure of the WHODAS-II in 6factors. The second order factor supports the existence of a global dimension of disability. The use of 4of the frequency items is not recommended in the scoring of the corresponding dimensions.
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Hepatitis C virus (HCV) replicates its genome in a membrane-associated replication complex, composed of viral proteins, replicating RNA and altered cellular membranes. We describe here HCV replicons that allow the direct visualization of functional HCV replication complexes. Viable replicons selected from a library of Tn7-mediated random insertions in the coding sequence of nonstructural protein 5A (NS5A) allowed the identification of two sites near the NS5A C terminus that tolerated insertion of heterologous sequences. Replicons encoding green fluorescent protein (GFP) at these locations were only moderately impaired for HCV RNA replication. Expression of the NS5A-GFP fusion protein could be demonstrated by immunoblot, indicating that the GFP was retained during RNA replication and did not interfere with HCV polyprotein processing. More importantly, expression levels were robust enough to allow direct visualization of the fusion protein by fluorescence microscopy. NS5A-GFP appeared as brightly fluorescing dot-like structures in the cytoplasm. By confocal laser scanning microscopy, NS5A-GFP colocalized with other HCV nonstructural proteins and nascent viral RNA, indicating that the dot-like structures, identified as membranous webs by electron microscopy, represent functional HCV replication complexes. These findings reveal an unexpected flexibility of the C-terminal domain of NS5A and provide tools for studying the formation and turnover of HCV replication complexes in living cells.
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The basic photosynthetic unit containing the reaction centre and the light-harvesting I complex (RC-LHI) of the purple non-sulphur bacterium Rhodospirillum rubrum was purified and reconstituted into two-dimensional (2D) membrane crystals. Transmission electron microscopy using conventional techniques and cryoelectron microscopy of the purified single particles and of 2D crystals yielded a projection of the RC-LHI complex at a resolution of at least 1.6 nm. In this projection the LHI ring appears to have a square symmetry and packs in a square crystal lattice. The square geometry of the LHI ring was observed also in images of single isolated particles of the RC-LHI complex. However, although the LHI units are packed identically within the crystal lattice, a new rotational analysis developed here showed that the reaction centres take up one of four possible orientations within the ring. This fourfold disorder supports our interpretation of a square ring symmetry and suggests that a hitherto undetected component may be present within the photosynthetic unit.