Sobre objetos familiares, en el ámbito de una teoría de objetos no existentes

Presentaré en este trabajo el resultado de una lectura de la teoría de objetos no existentes G-CCC de Héctor-Neri Castañeda. Me ocupare de la presentación de la teoría que efectúa en su artículo "Thinking and the Structure of the World.". Mi objetivo es, aquí, estudiar cuál es el lugar que cabe a los objetos familiares en su enfoque ontológico. Centraré mi exposición en ese aspecto, incluyendo en la discusión la interpretación de Orayen de esta teoría

Sobre objetos y ontología en la posición de Quine

El objetivo de este trabajo (que es resultado parcial de un proyecto de investigación) es mostrar que, si bien según Quine la ontología cumple sólo una función auxiliar en el marco del conocimiento científico, el rol que cabe a la noción de objeto en su visión de conjunto no es secundarlo Mostraré cómo se articulan estos temas con los aspectos centrales de su posición acerca del conocimiento, atendiendo en especial -a la función que cabe a la lógica en esta trama

Sobre la compatibilidad entre realismo y relativismo conceptual: un examen de la tesis de Putnam, desde un punto de vista lógico

Las indagaciones en la pregunta por lo que hay permiten distinguir a grandes rasgos entre dos enfoques: uno, el de los pensadores que entendieron que el tema a investigar era la naturaleza y estructura del mundo, y otro, el de aquellos quienes, al sostener que describir el mundo no es simplemente copiarlo, atendieron a lo que se llamó esquema conceptual: esto es, al marco conceptual cuya forma toman las descripciones del mundo. Desde el segundo enfoque cabe suponer, o bien (a) que una única estructura que no cambia subyace al conocimiento humano, o (b) que, dado el carácter dinámico e histórico del pensamiento humano, se desarrollan marcos conceptuales alternativos. El segundo enfoque, en cualquiera de sus dos formas, suele estar ligado a la convicción de que el mundo, tal como es, nos es inaccesible. La situación se puede plantear como un dilema, ninguno de cuyos cuernos permite alentar esperanzas de avances bien fundados. O bien se pretende describir el mundo, tal como es, sin contemplar el hecho de que esa descripción incluye elecciones conceptuales propias de un sujeto, o bien se centra la investigación en los rasgos de el/los esquema/s conceptual/es imprescindibles para construir una descripción del mundo, imposibilitando, con ello, el acceso a la realidad tal como ésta es.Facultad de Humanidades y Ciencias de la Educació

Tesis de doctorado: Sobre la compatibilidad entre realismo y relativismo conceptual. Un examen de la tesis de Putnam, desde un punto de vista lógico

Resumen de la tesis doctoral de la autora, dirigida por Alberto Moretti y defendida el 24 de agosto de 2005.Departamento de Filosofí

Sobre lógica y supuestos ontológicos en Quine y en Putnam

Putnam dedica sus conferencias Hermes (2001) a dar las razones por las que considera que la ontología, aunque ha sido útil como vehículo para transmitir muchas visiones filosóficas genuinas, ha dejado de serlo Menciona dos dificultades relacionadas con el tema denominado ontología. a) Atrás de este tema se encuentra la idea de que el mundo dicta una manera única verdadera de dividir al mundo en objetos, situaciones, propiedades. b) Otro error relacionado con la ontología es la Idea de que cada instancia de objetividad debe ser sustentada por objetos

Acerca de algunas observaciones de Putnarn sobre la revisabilidad de las leyes lógicas

El examen de la naturaleza de las leyes lógicas generó cbscus10nes (en el siglo XX) acerca de su revisabilidad. Se desarrollan en el marco de concepciones holistas, Bajo este punto de vista el conocimiento científico se ve como una alianza masiva de creencias que enfrentan colectiva (y no independientemente) el tribunal de la experiencia. Cuando se presentan dificultades, las revisiones necesarias pueden efectuarse dondequiera

Extensive Investigations on Radial Crack Formation in Labyrinth Seals of Aircraft Engines

Labyrinth seals are due to their non-contact function and their thermal resistance the state of the art in sealing technology for thermal turbomachinery such as jet engines. The purpose of labyrinth seals is to adjust or minimize the leakage between rotor and stator. However, because of transient flight manoeuvres and the resulting mechanical and thermal loads on the components, contact between rotating and stationary parts cannot be ruled out. The aim of this study is to extend the basic understanding of the mechanisms of hot crack formation in the components of a labyrinth seal during the rubbing process. Previous investigations at the Institute of Thermal Turbomachinery have shown that the thermally induced stress caused in connection with the thermal change of the material properties can lead to formation of the cracks in the seal fin. In order to get a deeper understanding of the complex crack initiation mechanisms, it is necessary to carry out fundamental experiments on simplified geometries. For this purpose, the stress conditions of a loaded labyrinth seal are applied to a cylindrical test specimen. It is fixed on both sides and subjected to thermo-cyclic load. To model a rubbing process of a labyrinth seal, the initial temperature of the cycle corresponds to the operating temperature of the rotor in a jet engine and the final temperature corresponds to the contact temperature during the rubbing process. The temperature change causes stress in the specimen due to the rigid mounting. In literature there are analytical considerations regarding the stress-strain curve in the seal fin and a possible pre-damage of the components by remaining tensile stress after the rubbing process. In this paper, these analytical approaches are compared with the test data. Also a residual tensile strength of the seal fin which is still to be tolerated is worked out depending on the temperature load. The stress reduction during heating is very significant and is considered in detail. Due to the high mechanical and thermal loads, the stress reduction is superimposed by relaxation and plastic deformation. For a separate consideration of these basic effects, FE simulations are carried out. The main findings are that stress and strain in the component depends on both the initial and the final temperature of the specimen. The final rubbing temperature mainly influences the remaining tensile stress. With the thus calculated remaining strength of the seal fin a probable crack formation could be determined. The evaluation of this data contributes significantly to the understanding of hot crack formation in labyrinth seal fins and is therefore the basis for the optimization of the sealing system with regard to robustness against rubbing processes

Membrane-Bound Catechol-O-Methyl Transferase in Cortical Neurons and Glial Cells is Intracellularly Oriented

Catechol-O-methyl transferase (COMT) is involved in the inactivation of dopamine in brain regions in which the dopamine transporter (DAT1) is sparsely expressed. The membrane-bound isoform of COMT (MB-COMT) is the predominantly expressed form in the mammalian central nervous system (CNS). It has been a matter of debate whether in neural cells of the CNS the enzymatic domain of MB-COMT is oriented toward the cytoplasmic or the extracellular compartment. Here we used live immunocytochemistry on cultured neocortical neurons and glial cells to investigate the expression and membrane orientation of native COMT and of transfected MB-COMT fused to green fluorescent protein (GFP). After live staining, COMT immunoreactivity was reliably detected in both neurons and glial cells after permeabilization, but not on unpermeabilized cells. Similarly, autofluorescence of COMT-GFP fusion protein and antibody fluorescence showed overlap only in permeabilized neurons. Our data provide converging evidence for an intracellular membrane orientation of MB-COMT in neurons and glial cells, suggesting the presence of a DAT1-independent postsynaptic uptake mechanism for dopamine, prior to its degradation via COMT

Corrigendum: Valenced action/inhibition learning in humans is modulated by a genetic variant linked to dopamine D2 receptor expression

Motivational salience plays an important role in shaping human behavior, but recent studies demonstrate that human performance is not uniformly improved by motivation. Instead, action has been shown to dominate valence in motivated tasks, and it is particularly difficult for humans to learn the inhibition of an action to obtain a reward, but the neural mechanism behind this behavioral specificity is yet unclear. In all mammals, including humans, the monoamine neurotransmitter dopamine is particularly important in the neural manifestation of appetitively motivated behavior, and the human dopamine system is subject to considerable genetic variability. The well-studied TaqIA restriction fragment length polymorphism (rs1800497) has previously been shown to affect striatal dopamine metabolism. In this study we investigated a potential effect of this genetic variation on motivated action/inhibition learning. Two independent cohorts consisting of 87 and 95 healthy participants, respectively, were tested using the previously described valenced go/no-go learning paradigm in which participants learned the reward-associated no-go condition significantly worse than all other conditions. This effect was modulated by the TaqIA polymorphism, with carriers of the A1 allele showing a diminished learning-related performance enhancement in the rewarded no-go condition compared to the A2 homozygotes. This result highlights a modulatory role for genetic variability of the dopaminergic system in individual learning differences of action-valence interaction