936 resultados para Higher-order functions
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This brief proposes a new method for the identification of fractional order transfer functions based on the time response resulting from a single step excitation. The proposed method is applied to the identification of a three-dimensional RC network, which can be tailored in terms of topology and composition to emulate real time systems governed by fractional order dynamics. The results are in excellent agreement with the actual network response, yet the identification procedure only requires a small number of coefficients to be determined, demonstrating that the fractional order modelling approach leads to very parsimonious model formulations.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Background Polymorphonuclear neutrophils (PMN) play a key role in host defences against invading microorganisms but can also potentiate detrimental inflammatory reactions in case of excessive or misdirected responses. Intravenous immunoglobulins (IVIg) are used to treat patients with immune deficiencies and, at higher doses, in autoimmune, allergic and systemic inflammatory disorders. Methodology/Principal Findings We used flow cytometry to examine the effects of IVIg on PMN functions and survival, using whole-blood conditions in order to avoid artifacts due to isolation procedures. IVIg at low concentrations induced PMN activation, as reflected by decreased L-selectin and increased CD11b expression at the PMN surface, oxidative burst enhancement, and prolonged cell survival. In contrast, IVIg at higher concentrations inhibited LPS-induced CD11b degranulation and oxidative burst priming, and counteracted LPS-induced PMN lifespan prolongation. Conclusions/Significance IVIg appears to have differential, concentration-dependent effects on PMN, possibly supporting the use of IVIg as either an anti-microbial or an anti-inflammatory agent.
Relative Predicativity and dependent recursion in second-order set theory and higher-orders theories
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This article reports that some robustness of the notions of predicativity and of autonomous progression is broken down if as the given infinite total entity we choose some mathematical entities other than the traditional ω. Namely, the equivalence between normal transfinite recursion scheme and new dependent transfinite recursion scheme, which does hold in the context of subsystems of second order number theory, does not hold in the context of subsystems of second order set theory where the universe V of sets is treated as the given totality (nor in the contexts of those of n+3-th order number or set theories, where the class of all n+2-th order objects is treated as the given totality).
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Mode of access: Internet.
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First order characterizations of pseudoconvex functions are investigated in terms of generalized directional derivatives. A connection with the invexity is analysed. Well-known first order characterizations of the solution sets of pseudolinear programs are generalized to the case of pseudoconvex programs. The concepts of pseudoconvexity and invexity do not depend on a single definition of the generalized directional derivative.
Foveation time measure in Congenital Nystagmus through second order approximation of the slow phases
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Congenital Nystagmus (CN) is an ocular-motor disorder characterised by involuntary, conjugated ocular oscillations, and its pathogenesis is still unknown. The pathology is de fined as "congenital" from the onset time of its arise which could be at birth or in the first months of life. Visual acuity in CN subjects is often diminished due to nystagmus continuous oscillations, mainly on the horizontal plane, which disturb image fixation on the retina. However, during short periods in which eye velocity slows down while the target image is placed onto the fovea (called foveation intervals) the image of a given target can still be stable, allowing a subject to reach a higher visual acuity. In CN subjects, visual acuity is usually assessed both using typical measurement techniques (e.g. Landolt C test) and with eye movement recording in different gaze positions. The offline study of eye movement recordings allows physicians to analyse nystagmus main features such as waveform shape, amplitude and frequency and to compute estimated visual acuity predictors. This analytical functions estimates the best corrected visual acuity using foveation time and foveation position variability, hence a reliable estimation of this two parameters is a fundamental factor in assessing visual acuity. This work aims to enhance the foveation time estimation in CN eye movement recording, computing a second order approximation of the slow phase components of nystag-mus oscillations. About 19 infraredoculographic eye-movement recordings from 10 CN subjects were acquired and the visual acuity assessed with an acuity predictor was compared to the one measured in primary position. Results suggest that visual acuity measurements based on foveation time estimation obtained from interpolated data are closer to value obtained during Landolt C tests. © 2010 IEEE.
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MSC2010: 30C45, 33C45
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The University of the West Indies (UWI), established in the British colony of Jamaica in 1948, was mandated to serve the “brightest and the best” of the British colonies. Unfortunately, the austerity of Jamaica's economy has not helped to augment an “open door” access to higher education, and UWI is often criticized for not implementing policies to sustain the democratization of higher education; it is accused of functioning as an elitist institution. ^ The purpose of this qualitative study was to determine whether UWI functions democratically as an institution to influence the equity of higher education in Jamaica. A review of the literature reveals many interpretations of the democratization of higher education. Three of Spaulding and Kargodorian's four criteria were utilized to analyze this research. They were (1) equality of access to higher education, (2) equality of participation within the institution of higher education, and (3) equality of educational results. Multiple sources of written data augmented by interviews in Jamaica and Miami were utilized. ^ The analysis revealed that UWI functions in a collaborative relationship with Jamaica's Centralized Educational System as well as with the country's political, economic, and social realms to impact the democratization of higher education. Documentation suggests that, although strong traditional influences continue to exist, UWI has deviated from its original mandate and instead, flexible admittance policies and diversification of expanded programs have contributed to greater accessibility. ^ Despite UWI's reports of improvements which have contributed to more access, UNESCO and some interviewees have not been impressed. A World Bank report on enrollment ratio at the university level in English speaking Caribbean countries reflects less than one percent of the age cohort. The Jamaicans interviewed, especially those from the lower class, felt that their democratic right to receive higher education was not met. UNESCO regards UWI's efforts as just putting a “dent” in the problem. ^ Recommendations include continuing efforts towards developing curricula more relevant to the Jamaican society, increasing distance education in order to ease UWI's load, expanding financial partnerships with private sectors, and extending research in collaboration with large local and foreign private companies. ^