Block of Kcnk3 by protons. Evidence that 2-P-domain potassium channel subunits function as homodimers.

KCNK subunits have two pore-forming P domains and four predicted transmembrane segments. To assess the number of subunits in each pore, we studied external proton block of Kcnk3, a subunit prominent in rodent heart and brain. Consistent with a pore-blocking mechanism, inhibition was dependent on voltage, potassium concentration, and a histidine in the first P domain (P1H). Thus, at pH 6.8 with 20 mm potassium half the current passed by P1H channels was blocked (apparently via two sites approximately 10% into the electrical field) whereas channels with an asparagine substitution (P1N) were fully active. Furthermore, pore blockade by barium was sensitive to pH in P1H but not P1N channels. Although linking two Kcnk3 subunits in tandem to produce P1H-P1H and P1N-P1N channels bearing four P domains did not alter these attributes, the mixed tandems P1H-P1N and P1N-P1H were half-blocked at pH approximately 6.4, apparently via a single site. This implicates a dimeric structure for Kcnk3 channels with two (and only two) P1 domains in each pore and argues that P2 domains also contribute to pore formation

A multiparameter family of irreducible representations of the quantum plane and of the quantum Weyl algebra

We construct a family of irreducible representations of the quantum plane and of the quantum Weyl algebra over an arbitrary field, assuming the deformation parameter is not a root of unity. We determine when two representations in this family are isomorphic, and when they are weight representations, in the sense of Bavula.Comment: 12 pages, Section 2 has been reorganized, new material added in a new Section

Ensaio comparativo avançado de arroz de sequeiro em Altamira, Pará - ano agrícola 1998/1999.

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Changing self-medication practices, lay knowledge and rationales

This text analyses lay knowledge and rationales in which self-medication practices are involved. After a brief critical review of the main theoretical landmarks in the analysis of lay knowledge compared with expert knowledge, the objective is to demonstrate the current forms of lay appropriation and reconversion of expert knowledge and the modes of expertisation that this shared knowledge reveals. The text discusses, on the one hand, the new forms of lay dependence on expert knowledge and, on the other, the sociological potential which these forms entail in terms of the development of new areas of lay autonomy, by focusing on the topic of self-medication and a typology of modes of lay cognitive construction, namely spontaneous knowledge, mediated knowledge and confirmed knowledge. The constructed nature of this knowledge, which is not simply mimetically reproduced from expert sources, reveals the need for a new epistemological dialogue between the different theoretical trends that explore the reflexivity of modern societies

Chamaecrista rotundifolia: leguminosa para controle de mato e adubação verde do solo.

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Multi-q Pattern Classification of Polarization Curves

Several experimental measurements are expressed in the form of one-dimensional profiles, for which there is a scarcity of methodologies able to classify the pertinence of a given result to a specific group. The polarization curves that evaluate the corrosion kinetics of electrodes in corrosive media are an application where the behavior is chiefly analyzed from profiles. Polarization curves are indeed a classic method to determine the global kinetics of metallic electrodes, but the strong nonlinearity from different metals and alloys can overlap and the discrimination becomes a challenging problem. Moreover, even finding a typical curve from replicated tests requires subjective judgement. In this paper we used the so-called multi-q approach based on the Tsallis statistics in a classification engine to separate multiple polarization curve profiles of two stainless steels. We collected 48 experimental polarization curves in aqueous chloride medium of two stainless steel types, with different resistance against localized corrosion. Multi-q pattern analysis was then carried out on a wide potential range, from cathodic up to anodic regions. An excellent classification rate was obtained, at a success rate of 90%, 80%, and 83% for low (cathodic), high (anodic), and both potential ranges, respectively, using only 2% of the original profile data. These results show the potential of the proposed approach towards efficient, robust, systematic and automatic classification of highly non-linear profile curves.Comment: 12 pages, 7 figure

Sistema de plantio direto agroecológico.

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Melhoria da produtividade da mandioca de verão através da consorciação com feijão caupi.

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