465 research outputs found

    COMO SER FUNDACIONALISTA NEOCLÁSSICO QUANTO À JUSTIFICAÇÃO EPISTÊMICA

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    Este artigo tem como objetivo mostrar que, apesar de suas diferenças teóricas, as teorias internalistas da justificação fundacional, propostas por defensores do fundacionalismo contemporâneo de inspiração cartesiana denominado “neoclássico”, têm na noção de consciência direta sua pedra angular quando procuram fornecer uma explicação de como a justificação de crenças básicas pode ser não inferencial e infalível, constituindo assim a base especialmente forte que, em sua concepção, é condição para o sucesso da posição fundacionalista. Essas teorias compartilham também o desafio de explicar como essa consciência direta pode desempenhar o papel epistêmico a ela atribuído, que constitui um aspecto teórico particularmente obscuro em todas essas teorias, sobre o qual procuramos lançar alguma luz

    Raman spectroscopy, a non-destructive solution to the study of glass and its alteration

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    This paper presents the potential of Raman spectroscopy, a non-destructive technique which can be applied in-situ, for the analyses of glass and their alteration. Recent analytical developments are summarised for different glass composition and practical examples are given. The paper describes how to extract compositional information from the glass, first based on the spectra profile to distinguish rapidly alkali silicate from alkaline-earth alkali silicate and lead alkali silicate glass, then using the spectral decomposition and correlations to extract quantitative data. For alkali silicate glasses, that are most prone to alteration, the spectral characteristics are described to interpret the alteration process (selective leaching or dissolution of the glass) from the Raman spectra of the altered glass. These developments have greatly widened the potential of the technique and supplement well its ability to measure the thickness of the altered layer and identify the crystalline deposits

    Virtude, agência e responsabilidade: uma perspectiva epistemológica

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    This article focus on the relevance of epistemic agency to analyze knowledge in terms of epistemic virtue, highlighting the strategy adopted by virtue epistemologists to argue for the thesis that we can be epistemic agents, responsible for our epistemic lives, even if our beliefs are involuntary states. While L. Zagzebski (2001), by way of epistemic Frankfurt-style cases, claims that considering epistemic agency as a necessary condition for knowledge allows to offer an analysis that escapes the famous Gettier objection, E. Sosa (2015) refines his theory, offering new argumentation for the idea that there is an epistemic domain where there can be agency and we can be responsible for our true beliefs because of the significance of our cognitive character in knowledge acquisition. My aim in presenting and comparing Zagzebski’s and Sosa’s proposals is to emphasize some aspects in the current state of the art in virtue epistemology that favor credit accounts of knowledge.O foco de interesse neste artigo se coloca na relevância da noção de agência para análises de conhecimento em termos de virtude epistêmica, destacando a estratégia assumida por epistemólogos da virtude na defesa da tese de que podemos ser agentes responsáveis pelo que constitui nossa vida epistêmica, apesar de nossas crenças serem estados involuntários.  Enquanto L. Zagzebski (2001), invocando casos epistêmicos do tipo Frankfurt, alega que considerar agência epistêmica como condição necessária para o conhecimento permite oferecer uma análise que escapa à famosa objeção de Gettier, E. Sosa (2015) refina sua teoria, oferecendo nova argumentação em favor da ideia de que há uma esfera epistêmica na qual podemos ser agentes e responsáveis pela aquisição de crenças verdadeiras devido à importância de nosso caráter cognitivo para a atribuição de conhecimento. Meu objetivo ao expor e comparar as posições de Zagzebski e de Sosa é colocar em relevo aspectos do atual estado da arte em epistemologia da virtude que favorecem explicações de conhecimento em termos de crédito

    Laborariaren gidaria

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    Dialecto : texto en euskera navarro-labortanoS. XX -- Periodo : último euskera modernoEuskalkia : nafar-lapurteraXX. md. -- Aroa : azken euskara modernoaDigitalización. Vitoria-Gasteiz : Fundación Sancho el Sabio, 2008Rústic

    Proliferative and morphological changes induced by vanadium compounds on Swiss 3T3 fibroblasts

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    Vanadium compounds are shown to have a mitogenic effect on fibroblast cells. The effects of vanadate, vanadyl and pervanadate on the proliferation and morphological changes of Swiss 3T3 cells in culture are compared. Vanadium derivatives induced cell proliferation in a biphasic manner, with a toxic-like effect at doses over 50 mM, after 24 h of incubation. Vanadyl and vanadate were equally potent at 2.5–10 mM. At 50 mM vanadate inhibited cell proliferation, whereas slight inhibition was observed at 100 mM of vanadyl. At 10 mM pervanadate was as potent as vanadate and vanadyl in stimulating fibroblast proliferation, but no effect was observed at lower concentrations. A pronounced cytotoxic-like effect was induced by pervanadate at 50 mM. All of these effects were accompanied by morphological changes: transformation of fibroblast shape from polygonal to fusiform; retraction with cytoplasm condensation; and loss of lamellar processes. The magnitude of these transformations correlates with the potency of vanadium derivatives to induce a cytotoxic-like effect: pervanadate > vanadate > vanadyl. These data suggest that the oxidation state and coordination geometry of vanadium determine the degree of the cytotoxicit

    Proliferative and morphological changes induced by vanadium compounds on Swiss 3T3 fibroblasts

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    Vanadium compounds are shown to have a mitogenic effect on fibroblast cells. The effects of vanadate, vanadyl and pervanadate on the proliferation and morphological changes of Swiss 3T3 cells in culture are compared. Vanadium derivatives induced cell proliferation in a biphasic manner, with a toxic-like effect at doses over 50 mM, after 24 h of incubation. Vanadyl and vanadate were equally potent at 2.5–10 mM. At 50 mM vanadate inhibited cell proliferation, whereas slight inhibition was observed at 100 mM of vanadyl. At 10 mM pervanadate was as potent as vanadate and vanadyl in stimulating fibroblast proliferation, but no effect was observed at lower concentrations. A pronounced cytotoxic-like effect was induced by pervanadate at 50 mM. All of these effects were accompanied by morphological changes: transformation of fibroblast shape from polygonal to fusiform; retraction with cytoplasm condensation; and loss of lamellar processes. The magnitude of these transformations correlates with the potency of vanadium derivatives to induce a cytotoxic-like effect: pervanadate > vanadate > vanadyl. These data suggest that the oxidation state and coordination geometry of vanadium determine the degree of the cytotoxicity.Facultad de Ciencias Exacta

    Effect of vanadium compounds on acid phosphatase activity

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    The direct effect of different vanadium compounds on acid phosphatase (ACP) activity was investigated. Vanadate and vanadyl but not pervanadate inhibited the wheat germ ACP activity. These vanadium derivatives did not alter the fibroblast Swiss 3T3 soluble fraction ACP activity. Using inhibitors of tyrosine phosphatases (PTPases), the wheat germ ACP was partially characterized as a PTPase. This study suggests that the inhibitory ability of different vanadium derivatives to modulate ACP activity seems to depend on the geometry around the vanadium atom more than on the oxidation state. Our results indicate a correlation between the PTPase activity and the sensitivity to vanadate and vanadyl cation.Facultad de Ciencias Exacta

    Synthesis of a new vanadyl(IV) complex with trehalose (TreVO): insulin-mimetic activities in osteoblast-like cells in culture

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    Vanadium compounds show interesting biological and pharmacological properties. Some of them display insulin-mimetic effects and others produce antitumor actions. The bioactivity of vanadium is present in inorganic species like the vanadyl(IV) cation or vanadate( V) anion. Nevertheless, the development of new vanadium derivatives with organic ligands which improve the beneficial actions and decrease the toxic effects is of great interest. On the other hand, the mechanisms involved in vanadium bioactivity are still poorly understood. A new vanadium complex of the vanadyl(IV) cation with the disaccharide trehalose (TreVO), Na6 [VO(Tre)2].4H2O, here reported, shows interesting insulin- mimetic properties in two osteoblast cell lines, a normal one (MC3T3E1) and a tumoral one (UMR106). The complex affected the proliferation of both cell lines in a different manner. On tumoral cells, TreVO caused a weak stimulation of growth at 5 lM but it inhibited cell proliferation in a dose-response manner between 50 and 100 lM. TreVO significantly inhibited UMR106 differentiation (15–25% of basal) in the range 5–100 lM. On normal osteoblasts, TreVO behaved as a mitogen at 5–25 lM. Different inhibitors of the MAPK pathway blocked this effect. At higher concentrations (75–100 lM), the complex was a weak inhibitor of the MC3T3E1 proliferation. Besides, TreVO enhanced glucose consumption by a mechanism independent of the PI3-kinase activation. In both cell lines, TreVO stimulated the ERK phosphorylation in a dose- and time-dependent manner. Different inhibitors (PD98059, wortmannin, vitamins C and E) partially decreased this effect, which was totally inhibited by their combination. These results suggest that TreVO could be a potential candidate for therapeutic treatments

    α6β4 integrin genetic variations (A380T and R1281W) and breast cancer risk in an Argentinian population

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    The α6β4 integrin is composed of the α6 and β4 subunits that are encoded by the ITGα6 and the ITGβ4 genes, respectively. The α6β4 main function is to intervene in lamination and epithelia integrity maintenance by cell-matrix interactions. This integrin appears to have importance in breast cancer malignancy, as well as other epithelial carcinomas. The aim of this work was to investigate the potential role of ITGα6 (A380T) and ITGβ4 (R1281W) genetic variations in breast cancer susceptibility, in a female population from the northeast region of Argentina (Misiones). We performed a case-control study of 85 breast cancer patients and 113 cancer-free controls. Genotyping was performed by RFLP-PCR. For ITGα6 (A380T) single nucleotide polymorphism, a high frequency of heterozygous genotype GA in cases compared to controls was observed, achieving values of 48% and 49%, respectively. No association between the A380T SNP and breast cancer development was found (Odds Ratio = 0.92; 95% Confidence Interval = 0.52-1.63; p = 0.884). In conclusion, we did not find evidence of an association between A380T (ITGα6) and the risk of developing breast cancer. The results represent the first report of these genetic variations in breast cancer; therefore, they are an important contribution to the literature.Facultad de Ciencias ExactasCentro de Química Inorgánic

    Evaluación de las propiedades tecnológicas de sedimentos colmatantes de cuerpos lénticos ubicados al sudeste del área metropolitana de Buenos Aires. Estúdio preliminar para la formulación del Proyecto Productivo Inclusivo : Parque Ladrillero en el partido

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    Fil: Couyoupetrou, L.. Instituto de Recursos Minerales (INREMI). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Rolny, D.. Laboratorio de Tecnología y Gestión Habitacional (LATEC). Facultad de Arquitectura y Urbanismo. Universidad Nacional de La Plata; ArgentinaFil: Hurtado, Martín Adolfo. Instituto de Geomorfología y Suelos (IGS). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Etcheverry, Ricardo Oscar. Instituto de Recursos Minerales (INREMI). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Cremaschi, G.. Laboratorio de Tecnología y Gestión Habitacional (LATEC). Facultad de Arquitectura y Urbanismo. Universidad Nacional de La Plata; ArgentinaFil: Forte, Luis M.. Instituto de Geomorfología y Suelos (IGS). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentin
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