Browsing by Issue Date, starting with "2012-08"
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- Implicit acquisition of grammars with crossed and nested non-adjacent dependencies: investigating the push-down stack modelPublication . Udden, Julia; Ingvar, Martin; Hagoort, Peter; Petersson, Karl MagnusA recent hypothesis in empirical brain research on language is that the fundamental difference between animal and human communication systems is captured by the distinction between finite-state and more complex phrase-structure grammars, such as context-free and context-sensitive grammars. However, the relevance of this distinction for the study of language as a neurobiological system has been questioned and it has been suggested that a more relevant and partly analogous distinction is that between non-adjacent and adjacent dependencies. Online memory resources are central to the processing of non-adjacent dependencies as information has to be maintained across intervening material. One proposal is that an external memory device in the form of a limited push-down stack is used to process non-adjacent dependencies. We tested this hypothesis in an artificial grammar learning paradigm where subjects acquired non-adjacent dependencies implicitly. Generally, we found no qualitative differences between the acquisition of non-adjacent dependencies and adjacent dependencies. This suggests that although the acquisition of non-adjacent dependencies requires more exposure to the acquisition material, it utilizes the same mechanisms used for acquiring adjacent dependencies. We challenge the push-down stack model further by testing its processing predictions for nested and crossed multiple non-adjacent dependencies. The push-down stack model is partly supported by the results, and we suggest that stack-like properties are some among many natural properties characterizing the underlying neurophysiological mechanisms that implement the online memory resources used in language and structured sequence processing.
- Changes in the yield of microphytobenthic chlorophyll from nutrients: Considering denitrificationPublication . Brito, Ana; Newton, Alice; Tett, Paul; Fernandes, TeresaThe yield of microphytobenthic (MPB) chlorophyll from nitrogen expresses the relationship between chlorophyll formation and nutrient consumption within the surface sediment. In shallow coastal lagoons MPB have an important role in chlorophyll dynamics and may represent the majority of microalgal chlorophyll pigments. Given that chlorophyll has been used as an indicator of eutrophication, the yield is of utmost importance. Furthermore, the yield is a key parameter in models that aims at predicting eutrophication. Estimates of the MPB yield have been previously obtained from a series of microcosm experiments. However, discrepant results in nitrogen fluxes suggested the importance of other processes such as denitrification. Therefore, denitrification rates were used for the calculation of nutrient fluxes and new yield estimates were obtained for muddy sediments. Whereas the earlier estimate obtained was of 4.1 g chl. ( mol N)−1, after including the denitrification rate in the calculation this value was reduced from 5 to 35%.
- Changes in physical and chemical parameters of the traditional portuguese product água-mel during the production processPublication . Figueira, A.C.; Cavaco, TeresaChanges in physical and chemical parameters (viscosity, total soluble solids and Hunter color parameters L*, a*, b*, chroma and hue angle) of água-mel were investigated throughout processing. Kinetic parameters for color change of heatprocessed água-mel were monitored. A zero-order kinetic model was applied to changes in L* and b*, while a* and C* were described using a first-order kinetic model. The heating process changed all three color parameters (L*, a*, b*), causing a shift toward the darker colors. Parameters L* decreased, while a*, b*, C* and hue angle (°h) increased during heating. Regarding changes in total soluble solids and in apparent viscosity, both fitted first-order kinetics. A direct relationship was found between the changes in these two parameters. The increase in both total soluble solids and viscosity affected a*, b* and C*. In addition, a flow diagram for the Portuguese água-mel production process has been established.
- Decavanadate, decaniobate, tungstate and molybdate interactions with sarcoplasmic reticulum Ca2+-ATPase: quercetin prevents cysteine oxidation by vanadate but does not reverse ATPase inhibitionPublication . Fraqueza, Gil; Carvalho, Luís A. E. Batista de; Marques, M. Paula M.; Maia, Luisa; Ohlin, C. André; Casey, William H.; Aureliano, M.Recently we demonstrated that the decavanadate (V10) ion is a stronger Ca2+-ATPase inhibitor than other oxometalates, such as the isoelectronic and isostructural decaniobate ion, and the tungstate and molybdate monomer ions, and that it binds to this protein with a 1 : 1 stoichiometry. The V10 interaction is not affected by any of the protein conformations that occur during the process of calcium translocation (i.e. E1, E1P, E2 and E2P) (Fraqueza et al., J. Inorg. Biochem., 2012). In the present study, we further explore this subject, and we can now show that the decaniobate ion, [Nb10 = Nb10O28]6−, is a useful tool in deducing the interaction and the non-competitive Ca2+-ATPase inhibition by the decavanadate ion [V10 = V10O28]6−. Moreover, decavanadate and vanadate induce protein cysteine oxidation whereas no effects were detected for the decaniobate, tungstate or molybdate ions. The presence of the antioxidant quercetin prevents cysteine oxidation, but not ATPase inhibition, by vanadate or decavanadate. Definitive V(IV) EPR spectra were observed for decavanadate in the presence of sarcoplasmic reticulum Ca2+- ATPase, indicating a vanadate reduction at some stage of the protein interaction. Raman spectroscopy clearly shows that the protein conformation changes that are induced by V10, Nb10 and vanadate are different from the ones induced by molybdate and tungstate monomer ions. Here, Mo and W cause changes similar to those by phosphate, yielding changes similar to the E1P protein conformation. The putative reduction of vanadium(V) to vanadium(IV) and the non-competitive binding of the V10 and Nb10 decametalates may explain the differences in the Raman spectra compared to those seen in the presence of molybdate or tungstate. Putting it all together, we suggest that the ability of V10 to inhibit the Ca2+- ATPase may be at least in part due to the process of vanadate reduction and associated protein cysteine oxidation. These results contribute to the understanding and application of these families of mono- and polyoxometalates as effective modulators of many biological processes, particularly those associated with calcium homeostasis.
- Internal structures in n-permutable varietiesPublication . Rodelo, DianaWe analyze the notions of reflexive multiplicative graph, internal category and internal groupoid for n-permutable varieties. (C) 2012 Elsevier B.V. All rights reserved.
- Mutations at the flavin binding site of ETF:QO yield a MADD-like severe phenotype in DrosophilaPublication . J. Gonçalves, Emanuel; Henriques, Barbara J.; Rodrigues, Joao V.; Prudencio, Pedro; Rocha, Hugo; Vilarinho, Laura; Martinho, Rui Goncalo; Gomes, Claudio M.Following a screening on EMS-induced Drosophila mutants defective for formation and morphogenesis of epithelial cells, we have identified three lethal mutants defective for the production of embryonic cuticle. The mutants are allelic to the CG12140 gene, the fly homologue of electron transfer flavoprotein:ubiquinone oxidoreductase (ETF:QO). In humans, inherited defects in this inner membrane protein account for multiple acyl-CoA dehydrogenase deficiency (MADD), a metabolic disease of beta-oxidation, with a broad range of clinical phenotypes, varying from embryonic lethal to mild forms. The three mutant alleles carried distinct missense mutations in ETF:QO (G65E, A68V and S104F) and maternal mutant embryos for ETF:QO showed lethal morphogenetic defects and a significant induction of apoptosis following germ-band elongation. This phenotype is accompanied by an embryonic accumulation of short- and medium-chain acylcarnitines (C4. C8 and 02) as well as long-chain acylcarnitines (C14 and C16:1), whose elevation is also found in severe MADD forms in humans under intense metabolic decompensation. In agreement the ETF:QO activity in the mutant embryos is markedly decreased in relation to wild type activity. Amino acid sequence analysis and structural mapping into a molecular model of ETF:QO show that all mutations map at FAD interacting residues, two of which at the nucleotide-binding Rossmann fold. This structural domain is composed by a beta-strand connected by a short loop to an alpha-helix, and its perturbation results in impaired cofactor association via structural destabilisation and consequently enzymatic inactivation. This work thus pinpoints the molecular origins of a severe MADD-like phenotype in the fruit fly and establishes the proof of concept concerning the suitability of this organism as,a potential model organism for MADD. (C) 2012 Elsevier B.V. All rights reserved.
- The process of landscape (trans)formation: a methodology for sustainable intervention in contemporary landscapePublication . Batista, Desidério; Costa, Miguel ReimãoResulting from two different evolutionary processes - 4000 million years of biological changes and the cultural process of human inhabitation of the planet - landscape makes evident the level of integration of its natural and cultural dimensions. The cultural context (ensuing from the transformations imposed by human population) affects the natural environment and the overall construction of landscape. For centuries, the relationship between society and territory was harmonious and balanced, producing urban, rural and natural constructed landscapes which were not only attractive and productive, but formed a core part of our shared heritage and the basis for our European identity. More recently, however, sectarian and utilitarian visions ruled by the principles of easy and maximum profit have become prevalent, side-by-side with new dominant trends of human intervention which have assisted in the adulteration and degradation of landscape. If a more sustainable approach to the organisation of contemporary landscape is to be defined, this will have to be based on the in-depth knowledge of its values, dynamics, problems and contradictions. This approach will have to jointly consider the landscape’s natural and cultural aspects in the planning process and use both of these dimensions for the definition of the objectives presiding landscape preservation and transformation. Only such a methodology, which respects the heritage and identity of landscape, can be said to foster the long-term development of both society and nature. In the context of the changeable dynamics typical of contemporary landscapes, this article contributes to the formulation of an intervention methodology based on an ecological and cultural reading of the landscape in order to apply the method used in landscape ecology to the conurbation of central Algarve coast.
- Phytoplankton and microbial plankton of the Bay of Biscay and Western Iberian ShelfPublication . Morán, Xosé Anxelu G.; Barbosa, Ana B.; Revilla, Marta; Bode, Antonio; Orive, Emma; Soudant, DominiqueThe region of the Northeast Atlantic represents a gradient between two oceanographic regimes: (i) the subtropical waters of southern Portugal and southwestern Spain, and (ii) the temperate waters characterizing the northwestern and northern Iberian coasts (Cantabrian Sea) and the rest of the Bay of Biscay along the French coast.
- Prediction of low frequency sound fields in buildings near railway linesPublication . Neves e Sousa, Albano; Lopes, Isabel; Carreira, A. S.The design of new buildings in the vicinity of railway lines must consider protection against noise and vibrations induced by railway traffic. However, the prediction methods available involve heavy numerical models which have frequency limitations. In this paper a prediction method combining finite elements (FEM) with natural mode analysis is presented for use in reinforced concrete buildings with heavy walls. The method considers 2D FEM models of the railway, ground and buildings to identify the transfer function of vibration from the railway to building foundations. Also 3D models of the buildings are considered to identify the transfer functions of vibration from foundations to walls and floors. Finally, as the impedance of heavy walls and floors is much higher than the acoustic impedance of air, the numerically assessed vibration fields of walls and floors are used to calculate sound fields in rooms by means of natural mode analysis. A set of in situ measurements were made in two different situations in order to calibrate the prediction method and also to identify the factors which most affect vibration and sound transmission.
- Accumulation of fatty acids in purslane grown in hydroponic salt stress conditionsPublication . Anastácio, Ana; Carvalho, Isabel Saraiva dePurslane (Portulaca oleracea L.) is the eighth most common plant distributed throughout the world being a heat- and drought-tolerant plant. In this study, we evaluated the effect of salinity on total amounts of fatty acids (FAs) and ω3/ω6 ratio in leaves of purslane. Plants exposed to four levels of chloride salinity in the root zone (60, 90, 120 and 240 mM NaCl) for 40 days showed no signs of toxicity or death. The main FAs detected were C16:0>C18:3>C18:2. The ratio of ω6 to ω3 was not changed with salt stress. Hierarchic cluster analysis brought together 60 and 90 mM NaCl in control plants, based on their FA content. The results of this study confirm the purslane as a plant rich in FAs whose consumption may contribute to dietary intake of ω3 polyunsaturated fatty acid, with obvious benefits to human health.