236 resultados para buffers


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The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.

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Biocathodes may be a suitable replacement of platinum in microbial fuel cells (MFCs) if the cost of MFCs is to be reduced. However, the use of enzymes as bio-cathodes is fraught with loss of activity as time progresses. A possible cause of this loss in activity might be pH increase in the cathode as pH gradients in MFCs are well known. This pH increase is however, accompanied by simultaneous increase in salinity; therefore salinity may be a confounding variable. This study investigated various ways of mitigating pH changes in the cathode of MFCs and their effect on laccase activity and decolourisation of a model azo dye Acid orange 7 in the anode chamber. Experiments were run with catholyte pH automatically controlled via feedback control or by using acetate buffers (pH 4.5) of various strength (100 mM and 200 mM), with CMI7000 as the cation exchange membrane. A comparison was also made between use of CMI7000 and Nafion 117 as the transport properties of cations for both membranes (hence their potential effects on pH changes in the cathode) are different.

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Om meer inzicht te krijgen in factoren die positief bijdragen aan de stress-reactiviteit van de docent wordt in deze studie onderzocht in hoeverre mentale veerkracht en docenten eigen effectiviteitsverwachting (DEE) een bufferende werking hebben in de samenhang tussen dagelijkse gebeurtenissen met stress en het positief (PA) en negatief affect (NA). Deze kennis kan gebruikt worden op zowel preventief (selectie) als curatief niveau. Het onderzoek is gedaan onder 41 docenten (leeftijd M=40, SD=9.2) uit verschillende typen onderwijs. Middels de experience sample methode werden gedurende een week activiteitsgerelateerde, sociale en gebeurtenisgerelateerde stress en de emotionele reactiviteit, geobjectiveerd in veranderingen in PA en NA gemeten. Vooraf de onderzoeksweek vulden zij twee vragenlijsten in betreffende mentale veerkracht en DEE. Het meten van positief en negatief affect (PA en NA), activiteitsgerelateerde, sociale en gebeurtenisgerelateerde stress gebeurde door middel van de Experience Sample Methode, zowel via papieren boekje als digitaal (smartphone, tablet, computer). Mentale veerkracht is gemeten met de RS-NL, DEE door middel van een vertaalde vragenlijst van de Teacher Self-Efficacy Scale. Door middel van een multi-level regressieanalysie werden tussen de drie stressmaten en de afhankelijke variabelen PA en NA zijn significante samenhangen gevonden. Volgens de verwachting speelt mentale veerkracht een modererende rol in de samenhang tussen de stressmaten en NA. DEE speelt een modererende rol in de samenhang tussen sociale stress en PA.

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Thesis (Ph.D.)--University of Washington, 2016-08

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Changes in cellular calcium concentration control a wide range of physiological processes, from the subsecond release of synaptic neurotransmitters, to the regulation of gene expression over months or years. Calcium can also trigger cell death through both apoptosis and necrosis, and so the regulation of cellular calcium concentration must be tightly controlled through the concerted action of pumps, channels and buffers that transport calcium into and out of the cell cytoplasm. A hallmark of cellular calcium signalling is its spatiotemporal complexity: stimulation of cells by a hormone or neurotransmitter leads to oscillations in cytoplasmic calcium concentration that can vary markedly in time course, amplitude, frequency, and spatial range. In this chapter we review some of the biological roles of calcium, the experimental characterisation of complex dynamic changes in calcium concentration, and attempts to explain this complexity using computational models. We consider the "toolkit" of cellular proteins which influence calcium concentration, describe mechanistic models of key elements of the toolkit, and fit these into the framework of whole cell models of calcium oscillations and waves. Finally, we will touch on recent efforts to use stochastic modelling to elucidate elementary calcium signal events, and how these may evolve into global signals.

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In recent years, sulfated polysaccharides from marine algae have emerged as an important class of natural biopolymers with potential application in human and veterinary health care, while taking advantage of the absence of potential risk of contamination by animal viruses. Among these, fucans isolated from the cell walls of marine brown alga have been study due to their anticoagulant, antithrombotic, anti-inflammatory and antiviral activities. These biological effects of fucans have been found to depend on the degree of sulfation and molecular size of the polysaccharide chains. In the present study, we examined structural features of a fucan extracted from brown alga Dictyota menstrualis and its effect on the leukocyte migration to the peritoneum. The sulfated polysaccharides were extracted from the brown seaweed by proteolytic digestion, followed by sequential acetone precipitation producing 5 fractions. Gel lectrophoresis using 0.05 M 1,3-diaminopropane-acetate buffer, pH 9.0, stained with 0.1% toluidine blue, showed the presence of sulfated polysaccharides in all fractions. The chemical analyses demonstrated that all fractions are composed mainly of fucose, xylose, galactose, uronic acid, and sulfate. Electrophoresis in agarose gel in three different buffers demonstrated that the fraction 2.0v have only one population of fucan. This compound was purify by exclusion molecular. It has shown composition of fucose, xilose, sulfate and uronic acid in molar ration of 1.0: 1.7: 1.1: 0.5 respectively. The effect of this heterofucan on the leukocyte migration was observed 6h after zymozan (mg/g) administration into the peritoneum. The heterofucan showed higher antimigratory activity, it decrease the migration of leukocyte in 83.77% to peritoneum. The results suggest that this fucan is a new antimigratory compound with potential pharmacological appications

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Dados suplementares associados com este artigo disponíveis na versão online em: http://dx.doi.org/10.1016/j.marpol.2016.06.021

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Actualmente, para la planeación de la cadena de suministro, las organizaciones utilizan métodos convencionales basados en modelos estadísticos que miran el pasado y no reconocen avances -- Con este estudio se busca proyectar el futuro estos procesos -- Para lograrlo se tiene en cuenta la metodología Demand Driven que, para cambiar esta situación, basa su teoría en la adaptación de la cadena logística para reaccionar ante la venta en tiempo real, mediante la organización de buffers o pequeñas cajas de inventario que según las características de la cadena tendrán distintas propiedades para garantizar siempre la disponibilidad de stock, al menor coste y cantidad posible -- Se pretende demostrar la metodología mediante un caso de empresa: la viabilidad del sistema para garantizar la reducción del capital invertido en inventarios, garantizando mayor flujo de capital para inversión en nuevos aspectos; se presupone mejora en servicio que se traduce en mayores ventas para la compañía y reducción de costos al tener menor nivel de inventarios -- Al realizar el ejemplo empresarial, este estudio entrega a los líderes de las organizaciones las herramientas necesarias para toma de decisiones sobre cambios estructurales en la forma de realizar su proceso de planeación y ventas operacionales en busca de adaptaciones a las necesidades del mercado cambiante y exigente en el que vivimos hoy, donde los consumidores buscan bajo costo, alta calidad y disponibilidad a la mano -- En este estudio se puede observar cómo se pueden incrementar los ingresos en un 20% con sólo mejorar el nivel de servicio y entregas a tiempo a los clientes

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Tese dout. em Psicologia Educacional, Faculdade de Ciências Humanas e Sociais, Univ. do Algarve, 2005

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Understanding factors that affect the distribution and abundance of species is critical to developing effective management plans for conservation. Our goal was to quantify the distribution and abundance of Canada Warbler (Cardellina canadensis), a threatened old-forest associate in Alberta, Canada. The Canada Warbler has declined across its range, including in Alberta where habitat loss and alteration from urban expansion, forestry, and energy development are changing the forest landscape. We used 110,427 point count survey visits from 32,287 unique survey stations to model local-level (150-m radius circular buffers) and stand-level (564-m radius circular buffers) habitat associations of the Canada Warbler. We found that habitat supporting higher densities of Canada Warblers was locally concentrated yet broadly distributed across Alberta’s boreal forest region. Canada Warblers were most commonly associated with older deciduous forest at the local scale, particularly near small, incised streams, and greater amounts of deciduous forest at the stand scale. Predicted density was lower in other forest types and younger age classes measured at the local scale. There was little evidence that local-scale fragmentation (i.e., edges created by linear features) influenced Canada Warbler abundance. However, current forestry practices in the province likely will reduce the availability of Canada Warbler habitat over time by cutting old deciduous forest stands. Our results suggest that conservation efforts aimed at Canada Warbler focus on retaining large stands of old deciduous forest, specifically stands adjacent to streams, by increasing the width of deciduous retention buffers along streams during harvest and increasing the size and number of old forest residual patches in harvested stands.

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Abstract: After developing many sensor networks using custom protocols to save energy and minimise code complexity - we have now experimented with standards-based designs. These use IPv6 (6LowPAN), RPL routing, Coap for interfaces and data access and protocol buffers for data encapsulation. Deployments in the Cairngorm mountains have shown the capabilities and limitations of the implementations. This seminar will outline the hardware and software we used and discuss the advantages of the more standards-based approach. At the same time we have been progressing with high quality imaging of cultural heritage using the RTIdomes - so some results and designs will be shown as well. So this seminar will cover peat-bogs to museums, binary-HTTP-like REST to 3500 year old documents written on clay.