888 resultados para two step sintering
Resumo:
Moderate resolution remote sensing data, as provided by MODIS, can be used to detect and map active or past wildfires from daily records of suitable combinations of reflectance bands. The objective of the present work was to develop and test simple algorithms and variations for automatic or semiautomatic detection of burnt areas from time series data of MODIS biweekly vegetation indices for a Mediterranean region. MODIS-derived NDVI 250m time series data for the Valencia region, East Spain, were subjected to a two-step process for the detection of candidate burnt areas, and the results compared with available fire event records from the Valencia Regional Government. For each pixel and date in the data series, a model was fitted to both the previous and posterior time series data. Combining drops between two consecutive points and 1-year average drops, we used discrepancies or jumps between the pre and post models to identify seed pixels, and then delimitated fire scars for each potential wildfire using an extension algorithm from the seed pixels. The resulting maps of the detected burnt areas showed a very good agreement with the perimeters registered in the database of fire records used as reference. Overall accuracies and indices of agreement were very high, and omission and commission errors were similar or lower than in previous studies that used automatic or semiautomatic fire scar detection based on remote sensing. This supports the effectiveness of the method for detecting and mapping burnt areas in the Mediterranean region.
Resumo:
In this work, we analyze the effect of incorporating life cycle inventory (LCI) uncertainty on the multi-objective optimization of chemical supply chains (SC) considering simultaneously their economic and environmental performance. To this end, we present a stochastic multi-scenario mixed-integer linear programming (MILP) coupled with a two-step transformation scenario generation algorithm with the unique feature of providing scenarios where the LCI random variables are correlated and each one of them has the desired lognormal marginal distribution. The environmental performance is quantified following life cycle assessment (LCA) principles, which are represented in the model formulation through standard algebraic equations. The capabilities of our approach are illustrated through a case study of a petrochemical supply chain. We show that the stochastic solution improves the economic performance of the SC in comparison with the deterministic one at any level of the environmental impact, and moreover the correlation among environmental burdens provides more realistic scenarios for the decision making process.
Resumo:
The direct electron transfer between indium–tin oxide electrodes (ITO) and cytochrome c encapsulated in different sol–gel silica networks was studied. Cyt c@silica modified electrodes were synthesized by a two-step encapsulation method mixing a phosphate buffer solution with dissolved cytochrome c and a silica sol prepared by the alcohol-free sol–gel route. These modified electrodes were characterized by cyclic voltammetry, UV–vis spectroscopy, and in situ UV–vis spectroelectrochemistry. The electrochemical response of encapsulated protein is influenced by the terminal groups of the silica pores. Cyt c does not present electrochemical response in conventional silica (hydroxyl terminated) or phenyl terminated silica. Direct electron transfer to encapsulated cytochrome c and ITO electrodes only takes place when the protein is encapsulated in methyl modified silica networks.
Resumo:
On January 20th, the International Atomic Energy Agency confirmed that Iran had been implementing its commitments as part of the Joint Plan of Action (JPA) agreed with the so-called ‘E3+3’ in Geneva (also known as P5+1) on 24 November 2013. The forging of this interim deal, the successful start to its implementation and the temporary sanctions relief represent resounding success for international diplomacy but they should not be allowed to conceal the underlying issues. Reaching agreement on the JPA was achieved at the cost of clarity over what is to follow and it was decided to eschew a structured agreement in favour of a two-step process. The stated aim of the negotiating parties remains that of starting the implementation of a comprehensive solution by November 2014. If agreement is not reached on a comprehensive solution by the expiry of the JPA by July 20th, the action plan can be renewed by mutual consent. The latter might well be the likeliest outcome of the forthcoming negotiations. Apart from the large gap between the E3+3 and Iranian positions on the substance of a final deal, several domestic policy constraints will likely define the parameters of what is achievable in the future. This CEPS Policy Brief argues that the best hope for success lies in continued engagement and consistent incremental progress in the negotiations, with structured concessions on both sides. This should occur, however, not in a two- but a three-step framework based on lengthening Iran’s ‘breakout’ period while re-engaging with the country both politically and economically. The EU is in a unique position to lead this process. Having greater flexibility than either the US or Iran, its main tasks will be that of maintaining the negotiating momentum and broadening dialogue with Iran.
Resumo:
EDITED VERSION SOON TO BE PUBLISHED In this paper the effect of decoupling on the capitalisation of agricultural subsidies into agricultural rents in Ireland are analysed using a dynamic rental equations estimated with a two step system GMM estimator that accounts for expectation error and endogenous regressors. The findings illustrate the importance of institutional details in determining the extent to which subsidies are capitalised. In the period prior to decoupling Pillar 1 subsidies were highly capitalised into Irish agricultural rents in both the short and the long run. Depending on the farm system considered between 58 to 80 cents per euro of subsidies were capitalised into agricultural rents. In the post decoupling period the rate at which Pillar 1 subsidies are capitalised into Irish agricultural rents is found to have declined. This change is likely due to short term character of the Irish agricultural land rental market, where 11 month rental periods predominate, and the freedom that the 2003 reform of the CAP offered farmers to consolidate entitlements established on rented land. The generally very short term nature of Irish agricultural rental contracts offered farmers an opportunity to consolidate entitlements that is unlikely to have arisen in other Member States with agricultural land rental markets characterised by long term contracts. The results in both the pre and post decoupling periods highlight the high degree of inertia of agricultural rents in Ireland, and the importance of accounting for dynamics when investigating the capitalisation of agricultural subsidies into land rents. The high degree of inertia in rents means that the impact of previously capitalised agricultural policy persists through time.
Resumo:
This paper investigates the relationship between female labour force participation rates and economic growth in southern Mediterranean countries. A two-step methodology involving econometric estimations and the use of a general equilibrium model was used for this purpose. The econometric estimations suggest that there is a U-shaped relationship between economic growth and female labour force participation rates and they indicate the presence of region-specific barriers impeding women's entry into the labour force in southern Mediterranean countries. The econometric results were fed into a general equilibrium model, the GEM-E3-MEDPRO, which was used to simulate two alternative assumptions on developments in female labour participation rates in the region up to 2030. The first of these simulated changes in female labour force participation rates arising from income level trends projected for the period 2015–2030 in southern Mediterranean countries. The second assumed the lowering of region-specific barriers which deter female labour force participation. The results of these simulations suggest that lower female labour force participation rates may lead to marginally lower economic growth in the region, while the removal of region-specific barriers to female labour force participation may encourage economic growth. This has important policy implications, suggesting that policies intended to remove such barriers could help to promote the growth of the region's economies.
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Planktic d18O and d13C records and point count records of biogenic, volcanic, and nonvolcanic terrigenous [ice-rafted debris (IRD)] sediment components from Hole 919A in the Irminger basin, northern North Atlantic provide a comprehensive dataset from which a paleoceanographic reconstruction for the last 630 kyr has been developed. The paleoceanographic evolution of the Irminger basin during this time contains both long-term patterns and significant developmental steps. One long-term pattern observed is the persistent deposition of hematite-stained ice-rafted debris. This record suggests that the modern and late Pleistocene discharges of icebergs from northern redbed regions to the Irminger Sea lie in the low end of the range observed over the last 630 kyr. In addition, Arctic front fluctuations appear to have been the main controlling factor on the long-term accumulation patterns of IRD and planktic biogenic groups. The Hole 919A sediment record also contains a long-term association between felsic volcanic ash abundances and light d18O excursions in both interglacial and glacial stages, which suggests a causal link between deglaciations and explosive Icelandic eruptions. A significant developmental step in the paleoceanographic reconstruction based on benthic evidence was for diminished supply of Denmark Strait Overflow Water (DSOW) beginning at ~380 ka, possibly initiated by the influx of meltwater from broad-scale iceberg discharges along the east Greenland coast. There is also planktic evidence of a two-step cooling of sea surface conditions in the Irminger basin, first at ~338-309 ka and later at ~211-190 ka, after which both glacials and interglacials were colder as the Arctic front migrated southeast of Site 919. In addition to offering these findings, this reconstruction provides a longer-term geologic context for the interpretation of more recent paleoceanographic events and patterns of deposition from this region.
Resumo:
Oxygen and carbon isotope records from benthic and planktonic foraminifera are presented for the past 35,000 years in the northeastern Atlantic. The results support the idea that the last deglaci-ation took place in two major steps (Duplessy et al., 1981 doi:10.1016/0031-0182(81)90096-1; Mix and Ruddiman, 1985 doi:10.1016/0277-3791(85)90015-0; Ruddiman, 1987; Fairbanks, 1989 doi:10.1038/342637a0), and conflict with theories calling for a strong reduction in North Atlantic deep-water formation to explain the abrupt cooling of the Younger Dryas cold period (Broecker et al., 1985 doi:10.1038/315021a0; Rind et al., 1986 doi:10.1007/BF01277044; Broecker et al., 1988 doi:10.1029/PA003i001p00001).