2,724 research outputs found

    Is the Private Language Argument a Transcendental Argument?

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    Comparisons between Kant´s critique of pure reason and Wittgenstein´s critique of language, which became current in analytic philosophy (Cf. e.g Hacker 1972, 30.) seem not far-fetched in view of the impetus for the destruction of dogmatic metaphysics both philosophers share. Their relevance would gain though by an elaboration of their dissimilarities rather than by just stressing similarities. An example of the former approach, Weinert (1983, 412) contrasts the tools both critics of metaphysics employ: the distinction between analytic and synthetic judgments, and the description of the logic of languageuse and in particular the ´Argument from Epistemic Operators´ (Wittgenstein 1961, sects. 6.5, 6.51; 1958, §§ 246, 247, 251, 303; references in the form of paragraphnumbers are to the latter text) respectively. The analysis of the employment of those tools in anti-metaphysical arguments -and Weinert treats the Private Language Argument (PLA) as such (427-429)- enables to uncover underlying assumptions, e.g. the implicit assumption in Kant of a prior conceptual relation between concepts to which his notion of analysis is to be applied (430-431) and Wittgenstein´s explicit doctrine that "ordinary language is alright� (434)

    Structural and Electronic Properties of Graphene and Silicene: An FP-(L)APW+lo Study

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    We report here the structural and electronic properties of graphene and silicene (silicon analogue of graphene) investigated using first-principles calculations of their ground state energies employing full-potential (linearized) augmented plane wave plus local orbital (FP-(L)APW+lo) method. On structure optimization, we found that the graphene-like honeycomb structure of Si is buckled (buckling parameter Δ=0.44\Delta = 0.44 \AA in constrast with graphene whose structure is planar (Δ=0.0\Delta = 0.0 \AA). In spite of the buckled-structure, silicene has an electronic structure similar to that of graphene. The results are in agreement with previous reports based on other methods. We have also calculated the lower bounds of the lattice constant "a""a" of these 2D systems, within the present method of study which are our new results.Comment: Presented in the International Conference on Physics of Emerging Functional Materials (PEFM-2010), 22-24 Sept. 2010, Mumbai, India; Eds. Dinesh K. Aswal and Anil K. Debnath, AIP Conf. Proc. 1313 (2010) 152-155. 4 figures, typographic errors in published version rectifie

    Turing's three philosophical lessons and the philosophy of information

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    In this article, I outline the three main philosophical lessons that we may learn from Turing's work, and how they lead to a new philosophy of information. After a brief introduction, I discuss his work on the method of levels of abstraction (LoA), and his insistence that questions could be meaningfully asked only by specifying the correct LoA. I then look at his second lesson, about the sort of philosophical questions that seem to be most pressing today. Finally, I focus on the third lesson, concerning the new philosophical anthropology that owes so much to Turing's work. I then show how the lessons are learned by the philosophy of information. In the conclusion, I draw a general synthesis of the points made, in view of the development of the philosophy of information itself as a continuation of Turing's work. This journal is © 2012 The Royal Society.Peer reviewe

    Gating NO Release from Nitric Oxide Synthase

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    We have investigated the kinetics of NO escape from Geobacillus stearothermophilus nitric oxide synthase (gsNOS). Previous work indicated that NO release was gated at position 223 in mammalian enzymes; our kinetics experiments include mutants at that position along with measurements on the wild type enzyme. Employing stopped-flow UV–vis methods, reactions were triggered by mixing a reduced enzyme/N-hydroxy-l-arginine complex with an aerated buffer solution. NO release kinetics were obtained for wt NOS and three mutants (H134S, I223V, H134S/I223V). We have confirmed that wt gsNOS has the lowest NO release rate of known NOS enzymes, whether bacterial or mammalian. We also have found that steric clashes at positions 223 and 134 hinder NO escape, as judged by enhanced rates in the single mutants. The empirical rate of NO release from the gsNOS double mutant (H134/I223V) is nearly as rapid as that of the fastest mammalian enzymes, demonstrating that both positions 223 and 134 function as gates for escape of the product diatomic molecule

    Comparative host specificity of human- and pig- associated Staphylococcus aureus clonal lineages.

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    Bacterial adhesion is a crucial step in colonization of the skin. In this study, we investigated the differential adherence to human and pig corneocytes of six Staphylococcus aureus strains belonging to three human-associated [ST8 (CC8), ST22 (CC22) and ST36(CC30)] and two pig-associated [ST398 (CC398) and ST433(CC30)] clonal lineages, and their colonization potential in the pig host was assessed by in vivo competition experiments. Corneocytes were collected from 11 humans and 21 pigs using D-squame® adhesive discs, and bacterial adherence to corneocytes was quantified by a standardized light microscopy assay. A previously described porcine colonization model was used to assess the potential of the six strains to colonize the pig host. Three pregnant, S. aureus-free sows were inoculated intravaginally shortly before farrowing with different strain mixes [mix 1) human and porcine ST398; mix 2) human ST36 and porcine ST433; and mix 3) human ST8, ST22, ST36 and porcine ST398] and the ability of individual strains to colonize the nasal cavity of newborn piglets was evaluated for 28 days after birth by strain-specific antibiotic selective culture. In the corneocyte assay, the pig-associated ST433 strain and the human-associated ST22 and ST36 strains showed significantly greater adhesion to porcine and human corneocytes, respectively (p<0.0001). In contrast, ST8 and ST398 did not display preferential host binding patterns. In the in vivo competition experiment, ST8 was a better colonizer compared to ST22, ST36, and ST433 prevailed over ST36 in colonizing the newborn piglets. These results are partly in agreement with previous genetic and epidemiological studies indicating the host specificity of ST22, ST36 and ST433 and the broad-host range of ST398. However, our in vitro and in vivo experiments revealed an unexpected ability of ST8 to adhere to porcine corneocytes and persist in the nasal cavity of pigs

    Electric field gradients in s-, p- and d-metal diborides and the effect of pressure on the band structure and Tc_c in MgB2_2

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    Results of FLMTO-GGA (full-potential linear muffin-tin orbital -- generalized gradient approximation) calculations of the band structure and boron electric field gradients (EFG) for the new medium-Tc_c superconductor (MTSC), MgB2_2, and related diborides MB2_2, M=Be, Al, Sc, Ti, V, Cr, Mo and Ta are reported. The boron EFG variations are found to be related to specific features of their band structure and particularly to the M-B hybridization. The strong charge anisotropy at the B site in MgB2_2 is completely defined by the valence electrons - a property which sets MgB2_2 apart from other diborides. The boron EFG in MgB2_2 is weakly dependent of applied pressure: the B p electron anisotropy increases with pressure, but it is partly compensated by the increase of core charge assymetry. The concentration of holes in bonding σ\sigma bands is found to decrease slightly from 0.067 to 0.062 holes/B under a pressure of 10 GPa. Despite a small decrease of N(EF_F), the Hopfield parameter increases with pressure and we believe that the main reason for the reduction under pressure of the superconducting transition temperature, Tc_c, is the strong pressure dependence of phonon frequencies, which is sufficient to compensate the electronic effects.Comment: 12 pages, 3 figure
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