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showing 10 items of 2571 documents
La mesura de l'ús de les llengües en els mitjans telemàtics
2020
La consolidació de l'entorn digital i totes les seues modalitats de comunicació ha ampliat les possibilitats d'interacció i, per tant, els àmbits d'ús de les llengües. Com a adaptació a aquesta nova realitat, en aquesta aproximació metodològica plantegem la combinació de diferents tècniques no reactives: explotació de fonts secundàries, observació sistemàtica, i mystery shopping. Les fonts d'observació directa ens permeten mesurar de manera efectiva l'ús de les llengües en la comunicació telemàtica. Els autors ho han aplicat específicament en l'administració local i en empreses de serveis. En l'àmbit administratiu, a més, això ens ha servit per a desenvolupar un índex global de presència de…
Disorder-induced gap in the normal density of states of the organic superconductorκ-(BEDT-TTF)2Cu[N(CN)2]Br
2015
The local density of states (DOS) of the organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br, measured by scanning tunneling spectroscopy on in situ cleaved surfaces, reveals a logarithmic suppression near the Fermi edge persisting above the critical temperature T(c). The experimentally observed suppression of the DOS is in excellent agreement with a soft Hubbard gap as predicted by the Anderson-Hubbard model for systems with disorder. The electronic disorder also explains the diminished coherence peaks of the quasi-particle DOS below T(c).
Simulating Term Structure of Interest Rates with Arbitrary Marginals
2007
Decision models under uncertainty need to be feeded with scenarios of the interest rate curve. Such scenarios have to comply, as close as possible, with the empirical distribution of each rate. Simulation models of the term structure usually assume that the conjugate distribution of the interest rates is lognormal. Dynamic models, like vector auto-regression, implicitly postulate that the logarithm of the interest rates is normally distributed. Statistical analyses have, however, shown that stationary transformations (yield changes) of the interest rates are substantially leptokurtic, thus posing serious doubts on the reliability of the available models. We propose in this paper a vector au…
Simulating term structure of interest rates with arbitrary marginals
2011
Decision models under uncertainty rely their analysis on scenarios of the economic factors. A key economic factor is the term structure of interest rates (yields). Simulation models of the yield curve usually assume that the conjugate distribution of the interest rates is lognormal. Dynamic models, like vector auto-regression, implicitly postulate that the logarithm of the interest rates is normally distributed. Statistical analyses have, however, shown that stationary transformations (yield changes) of the interest rates are substantially leptokurtic, thus posing serious doubts on the reliability of the available models. We propose in this paper a VARTA model (Biller and Nelson, 2003) to s…
Probabilistic and fuzzy logic in clinical diagnosis
2007
In this study I have compared classic and fuzzy logic and their usefulness in clinical diagnosis. The theory of probability is often considered a device to protect the classical two-valued logic from the evidence of its inadequacy to understand and show the complexity of world [1]. This can be true, but it is not possible to discard the theory of probability. I will argue that the problems and the application fields of the theory of probability are very different from those of fuzzy logic. After the introduction on the theoretical bases of fuzzy approach to logic, I have reported some diagnostic argumentations employing fuzzy logic. The state of normality and the state of disease often figh…
MRI abnormalities following repeated and incoming seizures.
2010
Abstract Neuroimaging, an important diagnostic tool frequently used in the evaluation of patients with epilepsy, has mainly the aim to identify structural abnormalities needing a treatment and to contribute to the definition of the aetiology. Brain magnetic resonance imaging (MRI) in epilepsy is more sensitive than computerized tomography (CT) scan for detecting abnormalities. Status epilepticus (SE) and repeated incoming seizures may determine extensive and transient or long lasting pronounced MRI changes. We describe a case of a 41-year-old woman with a history of brain neoplasm, whose contrast-enhanced MRI images following repeated and incoming seizures were characterized either by rever…
Adaptive control of a drilling system with unknown time-delay and disturbance
2016
In this paper, we address adaptive predictor feedback design for a simplified drilling system in the presence of disturbance and time-delay. The main objective is to stabilize the bottomhole pressure at a critical depth at a desired set-point directly. The stabilization of the dynamic system and the asymptotic tracking are demonstrated by the proposed adaptive control, where the adaptation employs Lyapunov update law design with normalization. The proposed method is evaluated using a high fidelity drilling simulator and cases from a North Sea drilling operation are simulated. The results show that the proposed predictor controller is effective to stabilize the bottom hole pressure within th…
Adaptive predictor control for stabilizing pressure in a managed pressure drilling system under time-delay
2016
Abstract In this paper, we address adaptive predictor feedback design for a simplified ODE drilling system in the presence of unknown parameter, disturbance and time-delay. The main objective is to stabilize the bottomhole pressure at a critical depth at a desired set-point directly. The time-delay in the transmission line of the drilling systems is considered. The stabilization of the dynamic system and the asymptotic tracking are demonstrated by the proposed predictor control, where the adaptation employs Lyapunov update law design with normalization. The proposed method is evaluated using a high fidelity drilling simulator and cases from a North Sea drilling operation are simulated. The …
mTORC1 activation in B cells confers impairment of marginal zone microarchitecture by exaggerating cathepsin activity
2018
Mammalian target of rapamycin complex 1 (mTORC1) is a key regulator of cell metabolism and lymphocyte proliferation. It is inhibited by the tuberous sclerosis complex (TSC), a heterodimer of TSC1 and TSC2. Deletion of either gene results in robust activation of mTORC1. Mature B cells reside in the spleen at two major anatomical locations, the marginal zone (MZ) and follicles. The MZ constitutes the first line of humoral response against blood‐borne pathogens and undergoes atrophy in chronic inflammation. In previous work, we showed that mice deleted for TSC1 in their B cells (TSC1(BKO)) have almost no MZ B cells, whereas follicular B cells are minimally affected. To explore potential underl…
Essays on the Spanish REIT market
2021
Los Real Estate Investment Trust (REIT), equivalentes a la figura española de las Sociedades Anónimas Cotizadas de Inversión en el Mercado Inmobiliario (SOCIMI), son instrumentos de inversión colectiva cuyo propósito es la tenencia directa o indirecta de activos inmobiliarios para el alquiler. El incremento de las salidas a bolsa de estos vehículos de inversión en Europa en los últimos años ha permitido el estudio de estos mercados cuya importancia y tamaño ha crecido notablemente. En España, la primera SOCIMI se incorporó al mercado a finales de 2013 y desde ese momento se ha producido un rápido crecimiento en el número y tamaño de estas sociedades. A lo largo de esta Tesis Doctoral se ha …