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Search Results: 1 - 10 of 208204 matches for " Alexandre N; "
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Estruturas em movimento: alguns tópicos sobre as constru es-Q e de clivagem
Alexandre, Nélia
Letras de Hoje , 2006,
Frege, psicologismo e o problema da linguagem privada
Alexandre N. Machado
Barbarói , 2007,
Abstract: O presente artigo visa mostrar que um dos argumentos de Frege contra o psicologismo, o argumento da comunicabilidade, pressup e duas teses que implicam a possibilidade de uma linguagem privada, no sentido de Wittgenstein (uma linguagem que apenas uma pessoa pode entender), a saber, (1) que as representa es mentais (Vorstellungen) s o epistemicamente privadas e inalienáveis e (2) que para saber o que um termo geral significa, deve-se conhecer aquilo ao qual ele se refere. Abstract The present article seeks to show that one of Frege’s arguments against the psychologism, the argument of the communication, presupposes two thesis that implicate the possibility of a private language, in the sense of Wittgenstein (a language that just one person can understand), to know, (1) that the mental representations (Vorstellungen) are epistemically deprived and inalienable and (2) that in order to know what a general term means, it is necessary to know what it refers to.
Conhecimento, Verdade e Significado
Alexandre N. Machado
DoisPontos , 2009,
Abstract: This paper’s goal is to present a Wittgenstein’s argument against philosophical realism, the strong realism with respect to truth. Wittgenstein’s argument has the general form of a modus tollens whose conditional premise states that strong realism regarding truth implies the massive error hypothesis. The consequent’s denial is based on the incompatibility between the massive error hypothesis and language’s essential normativity. Wittgenstein’s argument is also compatible with realism’s weak version regarding truth. In the last section I examine Stroud’s argument against Austin’s thesis presupposed in his argument against skepticism according to which truths about the usage of “knowledge” (and related expressions) imply truths about knowledge. I try to show that Stroud’s argument involves the type of realism targeted by Wittgenstein’s argument.
Nota Sobre a Dúvida Cartesiana
Alexandre N. Machado
DoisPontos , 2007,
Abstract: The aim of this note is to formulate questions that make evident certain difficulties involved in understanding the methodical Cartesian doubt. It is a critical evaluation that starts from the following hypothesis: either the methodical doubt is unintelligible or it is not a doubt. Prima facie, the methodical doubt seems to be irrational, for in its scope we find propositions that seem to be paradigms of rationality. Some explanations of the intelligibility of the methodical doubt seem to take away its doubting character, like those that seek to make the methodical doubt and the belief compatible. The main questions dealt with in this note are: (1) What is the epistemic motivation for the methodical doubt? (2) Given what is available to the meditator in the First Meditation, can what is presented as a reason for doubting really be so regarded? (3) Is the methodical doubt compatible with the epistemic demands of practical life? (4) What is the nature of the attitude called “doubt” and what is its object?
Optical Spectrometer with Acousto-Optical Dynamic Grating for Guillermo Haro Astrophysical Observatory  [PDF]
Alexandre S. Shcherbakov, Adán Omar Arellanes, Vahram Chavushyan
International Journal of Astronomy and Astrophysics (IJAA) , 2013, DOI: 10.4236/ijaa.2013.34043

Optical spectrometer of the Guillermo Haro astrophysical observatory (Mexico) realizes investigations in the visible and near-infrared range 350 - 800 nm and exploits mechanically removable traditional static diffraction gratings as dispersive elements. There is a set of the static gratings with slit-densities 150 - 600 lines/mm and optical apertures 9 cm × 9 cm that provide the first order spectral resolution from 0.8 to 3.2 A/pixel, respectively. However, the needed mechanical manipulations, namely, replacing the static diffraction gratings with various resolutions and following recalibration of spectrometer within studying even the same object are practically inconvenient and lead to wasting rather expensive observation time. We suggest exploiting an acousto-optical cell, i.e. the dynamic diffraction grating tunable electronically, as dispersive element in that spectrometer. Involving the acousto-optical technique, which can potentially provide electronic control over the spectral resolution and the range of observations, leads to eliminating the abovementioned demerits and improving the efficiency of analysis.

Volatile Compounds Selection via Quantile Correlation and Composite Quantile Correlation: A Whiting Case Study  [PDF]
Ibrahim Sidi Zakari, Assi N’guessan, Alexandre Dehaut, Guillaume Duflos
Open Journal of Statistics (OJS) , 2016, DOI: 10.4236/ojs.2016.66079
Abstract: The freshness and quality indices of whiting (Merlangius merlangus) influenced by a large number of chemical volatile compounds, are here analyzed in order to select the most relevant compounds as predictors for these indices. The selection process was performed by means of recent statistical variable selection methods, namely robust model-free feature screening, based on quantile correlation and composite quantile correlation. On the one hand, compounds 2-Methyl-1-butanol, 3-Methyl-1-butanol, Ethanol, Trimethylamine, 3-Methyl butanal, 2-Methyl-1-propanol, Ethylacetate, 1-Butanol and 2,3-Butanedione were identified as major predictors for the freshness index and on the other hand, compounds 3-Methyl-1-butanol, 2-Methyl-1- butanol, Ethanol, 3-Methyl butanal, 3-Hydroxy-2-butanone, 1-Butanol, 2,3-Butane- dione, 3-Pentanol, 3-Pentanone and 2-Methyl-1-propanol were identified as major predictors for the quality index.
Dark Energy as an off-shell Tachyon Background in four-dimensional Strings
J. Alexandre,N. E. Mavromatos
Physics , 2009, DOI: 10.1016/j.physletb.2009.11.033
Abstract: We consider a time-dependent bosonic string in graviton, dilaton and tachyon backgrounds, for which it was already shown that conformal invariance is respected to all orders in alpha' and in any space-time dimension. Assuming that the tachyon is off-shell, we show in this note that the specific time-homogeneity of the corresponding space time effective action leads to a power-law expanding Universe, that can be accelerating or decelerating, depending on the range of parameter space considered. We interpret this result as dark energy. We arrive at this result without requiring the knowledge of the structure of the string effective action, which is not known to all orders in alpha'. Moreover, in our approach, the background configurations are consistent in a four-dimensional space time, without any need for extra dimensions.
Wilsonian renormalization group properties of a novel non-critical cosmological string configuration
J. Alexandre,N. E. Mavromatos
Physics , 2006,
Abstract: We show that an exact, non-critical-string cosmological configuration of dilaton and graviton backgrounds, found in [1], constitutes an infrared stable fixed point of an exact Wilsonian renormalization group equation.
A family of vortex rings and a variational application to potential flows around three-dimensional bodies
Pesce, Celso P.;Simos, Alexandre N.;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2008, DOI: 10.1590/S1678-58782008000200004
Abstract: a variational formulation and solution of general three-dimensional potential flows gave rise to the construction of a special family of ?trial functions?. this family is composed by circular-sector vortex rings, here named α-rings, i.e., rings that are positioned on the border of a circular sector with aperture angle α. an explicit formula for the velocity potential describing the α-rings family is here derived. a particular case is the well-known circular vortex-ring. the formula is given in terms of a uniformly valid series involving trigonometric and hypergeometric functions. results concerning the complete circular ring are compared to the well-known solution given, in closed form, in terms of bessel functions, validating the present formula. convergence is discussed. graphical examples are shown for various rings of different sector angles. as an elementary application, the steady potential flow around three-dimensional bodies in unbounded fluid is formulated and solved under the variational approach. the variational method is fully validated through the sphere problem and for a family of spheroids. examples concerning either translatory or rotatory motion around a transversal axis are presented for the spheroid family.
Structural analysis of the vegetation on a highland granitic rock outcrop in Southeast Brazil
Caiafa, Alessandra N.;Silva, Alexandre F. da;
Brazilian Journal of Botany , 2007, DOI: 10.1590/S0100-84042007000400010
Abstract: granitic rock outcrops of the brazilian southeast are either coastal or inland. the latter can often have high altitudes, such as in the summits of "serra do mar" and "serra da mantiqueira", where they are known as "campos de altitude". the landscape on these high altitude plateaux is often a mosaic of shrubs and treelets within a bunchgrass matrix, with sparse pteridophytes and other herbs, interspersed with variable extensions of rock outcrops. despite the pervasiveness of rock outcrops in the brazilian landscape, studies on the structural analysis of the vegetation on such formations are scarce. this study aimed to analyze the structure of the vegetation on a highland granitic rock outcrop in "parque estadual da serra do brigadeiro", state of minas gerais, southeast brazil (42°20' - 42°40' s and 20°20' - 21°00' w, 1,722 m of elevation ). quantitative parameters of absolute and relative frequency and dominance (cover) were estimated. the group analysis used the jaccard similarity index. trilepis lhotzkiana, panicum sp. 1, and vellozia variegata presented the highest relative frequencies, relative dominances and importance values. these three species, along with dyckia bracteata, rhynchospora emaciate, and tibouchina cf. manicata, represented 98.3% of the relative dominance. the remaining 1.7% referred to 22 remaining species. the distinction among quadrats within formed groups by cluster analysis was due to the great number of low frequency species.
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