152 research outputs found

    A concentration phenomenon for semilinear elliptic equations

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    For a domain \Omega\subset\dR^N we consider the equation -\Delta u + V(x)u = Q_n(x)\abs{u}^{p-2}u with zero Dirichlet boundary conditions and p(2,2)p\in(2,2^*). Here V0V\ge 0 and QnQ_n are bounded functions that are positive in a region contained in Ω\Omega and negative outside, and such that the sets {Qn>0}\{Q_n>0\} shrink to a point x0Ωx_0\in\Omega as nn\to\infty. We show that if unu_n is a nontrivial solution corresponding to QnQ_n, then the sequence (un)(u_n) concentrates at x0x_0 with respect to the H1H^1 and certain LqL^q-norms. We also show that if the sets {Qn>0}\{Q_n>0\} shrink to two points and unu_n are ground state solutions, then they concentrate at one of these points

    Greenhouse microclimate real-time monitoring based on wireless sensor network and gis

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    Trabalho apresentado em XX IMEKO World Congress Metrology for Green Growth, 9-14 setembro de 2012, Busan, Coreia do SulThe usage of greenhouse with controlled microclimate represents an important way to increase the production of fruits and vegetables considering the plants needs and has recently become one of the hottest topics in precision agriculture. In order to know and to control the greenhouse microclimate smart sensing nodes with wireless communication capabilities represents the solution. As one of promissory protocol associated with wireless sensor network can be mentioned the ZigBee due to its low cost, low power consumption, extended ranges and architecture flexibility. In the present work a sensing and control sensing nodes with ZigBee communication capabilities are considered, while the microclimate is monitored using a set of solid state sensors for temperature, relative humidity, light intensity and CO2 concentration considering this parameters with important role in plants growing. Every sensor node uses energy from a solar cell through a battery charger circuit considering also the powering of the sensing and control node during the night periods. The data from ZigBee network nodes are sent to Wireless-Ethernet gateway connected to a computer that runs a LabVIEW application that perform primary processing and web geographic information system that provides information about the greenhouse microclimate. Elements related power harvesting for implemented wireless sensor network, as so as a set of experimental results are included in the present work.N/

    Desempenho reprodutivo de vacas Nelore mantidas em pastagem nativa com suplementação na seca.

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    Caracteristicas e criopreservação do semen de bovinos da raça pé-duro no Estado do Piaui.

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    Bacterial cellulose as a support for the growth of retinal pigment epithelium

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    The feasibility of bacterial cellulose (BC) as a novel substrate for retinal pigment epithelium (RPE) culture was evaluated. Thin (41.6 ± 2.2 m of average thickness) and heatdried BC substrates were surface modified via acetylation and polysaccharide adsorption, using chitosan and carboxymethyl cellulose. All substrates were characterized according to their surface chemistry, wettability, energy, topography and also regarding their permeability, dimensional stability, mechanical properties and endotoxin content. Then, their ability to promote RPE cell adhesion and proliferation in vitro was assessed. All surface-modified BC substrates presented similar permeation coefficients with solutes of up to 300 kDa. Acetylation of BC decreased its swelling and the amount of endotoxins. Surface modification of BC greatly enhanced the adhesion and proliferation of RPE cells. All samples showed similar stress-strain behavior; BC and acetylated BC showed the highest elastic modulus, but the latter exhibited a slightly smaller tensile strength and elongation at break as compared to pristine BC. Although similar proliferation rates were observed among the modified substrates, the acetylated ones showed higher initial cell adhesion. This difference may be mainly due to the moderately hydrophilic surface obtained after acetylation.The authors acknowledge the Portuguese Foundation for Science and Technology (FCT, Portugal) for the financial support provided by the Research Grants SERH/BD/63578/2009, SFRH/BD/64901/2009, SFRH/BPD/64958/2009, and SFRH/BPD/63148/2009 for S.G., J.P., J.P.S., and V.S., respectively. The authors also acknowledge the Projects PEst-OE/EQB/LA0004/2013, PEst-OE/EQB/LA0023/2013, PTDC/BBB-BQB/2450/2012, and RECI/BBB-EBI/0179/2012 (Number: FCOMP-01-0124-FEDER-027462), cofunded by QREN, FEDER

    Emerging Enteropathogenic Escherichia coli Strains?

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    Escherichia coli strains of nonenteropathogenic serogroups carrying eae but lacking the enteropathogenic E. coli adherence factor plasmid and Shiga toxin DNA probe sequences were isolated from patients (children, adults, and AIDS patients) with and without diarrhea in Brazil. Although diverse in phenotype and genotype, some strains are potentially diarrheagenic

    High stretch induces endothelial dysfunction accompanied by oxidative stress and actin remodeling in human saphenous vein endothelial cells

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    The rate of the remodeling of the arterialized saphenous vein conduit limits the outcomes of coronary artery bypass graft surgery (CABG), which may be influenced by endothelial dysfunction. We tested the hypothesis that high stretch (HS) induces human saphenous vein endothelial cell (hSVEC) dysfunction and examined candidate underlying mechanisms. Our results showed that in vitro HS reduces NO bioavailability, increases inflammatory adhesion molecule expression (E-selectin and VCAM1) and THP-1 cell adhesion. HS decreases F-actin in hSVECs, but not in human arterial endothelial cells, and is accompanied by G-actin and cofilin’s nuclear shuttling and increased reactive oxidative species (ROS). Pre-treatment with the broad-acting antioxidant N-acetylcysteine (NAC) supported this observation and diminished stretch-induced actin remodeling and inflammatory adhesive molecule expression. Altogether, we provide evidence that increased oxidative stress and actin cytoskeleton remodeling play a role in HS-induced saphenous vein endothelial cell dysfunction, which may contribute to predisposing saphenous vein graft to failure
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