916 resultados para two-step process


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The thesis is made of three independent chapters interested in the impact of globalization on workers in industrialized countries. The dissertation is especially focused on identifying the causal impact of international trade on workers' mobility, wages, and employment with both a short- and medium-term perspective. The first paper explores the relation between intra-industry trade (IIT) expansion and associated worker flows, taking the latter as an indicator of labor-market adjustment costs. Being the first study to combine theoretical simulations and a novel identification strategy, we find that both theoretical and empirical analyses are consistent with the "smooth adjustment hypothesis", according to which IIT expansion is less disruptive than inter-industry trade expansion. The study therefore lends support to the use of IIT indices as first-pass proxies for the adjustment effects of trade expansion. The second chapter contrasts the impact of increased import competition coming from China and the European Union (EU) on workers in the United Kingdom over a 15-year period. The most salient findings show that increased imports from China had significantly negative effects on workers' earnings, wages and employment. In contrast, larger imports from the EU are associated with positive worker-level outcomes, which is largely explained by the fact that increased imports from the EU were mostly offset by increased same-industry exports to the EU. Besides, we find that increased imports from China exert additional pressure on workers through spillovers to employment and wages in downstream industries. Finally, the last chapter is focused on the impact of exposure to trade and real exchange rate shocks on wages for Swiss manufacturing workers. A particular attention is made to consistently estimate the causal effect in using a two-step gravity-type identification strategy. The study shows that the impact of trade and exchange rate movements is concentrated among high-skilled workers almost exclusively.

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We provide robust and compelling evidence of the marked impact of tertiary education on the economic growth of less developed countries and of its the relatively smaller impact on the growth of developed ones. Our results argue in favor of the accumulation of high skill levels especially in technologically under-developed countries and, contrary to common wisdom, independently of the fact that these economies might initially produce lower-technology goods or perform technology imitation. Our results are robust to the different measures used in proxying human capital and to the adjustments made for cross-country differences in the quality of education. Country-specific institutional quality, as well as other indicators including legal origin, religious fractionalization and openness to trade have been used to control for the robustness of the results. These factors are also shown to speed up technology convergence thereby confirming previous empirical studies. Our estimates tackle problems of endogeneity by adopting a variety of techniques, including instrumental variables -for both panel and cross-section analyses- and the two-step efficient dynamics system GMM.

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We investigate what processes may underlie heterogeneity in social preferences. We address this question by examining participants' decisions and associated response times across 12 mini-ultimatum games. Using a finite mixture model and cross-validating its classification with a response time analysis, we identified four groups of responders: one group takes little to no account of the proposed split or the foregone allocation and swiftly accepts any positive offer; two groups process primarily the objective properties of the allocations (fairness and kindness) and need more time the more properties need to be examined; and a fourth group, which takes more time than the others, appears to take into account what they would have proposed had they been put in the role of the proposer. We discuss implications of this joint decision-response time analysis.

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Using a database of 2,263 responses to R&D public calls in Catalonia, during the period 2007–2010, this paper proceeds to analyse the potential interaction of the territorial and policy dimensions with the propensity to apply for, and be awarded, a public R&D subsidy. Controlling for characteristics at the firm and project level, we estimate models using a two-step procedure. In the first step, our results suggest that large firms which export and which belong to high-tech manufactures are more likely to participate in a public R&D call. Furthermore, both urban location and past experience of such calls have a positive effect. Our territorial proxy of information spillovers shows a positive sign, but this is only significant at intra-industry level. Membership of one of the sectors prioritized by the Catalan government, perhaps surprisingly, does not have a significant impact. In the second step, our results show that cooperative projects, SMEs or old firms shows a positive effect on the probability of obtaining a public subsidy. Finally, the cluster policy does not show a clear relationship with the public R&D call, suggesting that cluster policies and R&D subsidies follow different goals. Our results are in line with previous results in the literature, but they highlight the unequal territorial distribution of the firms which apply and the fact that policymakers should interlink the decision criteria for their public call with other policies. Keywords: Evaluation, R&D policies, territorial approach, clusters JEL Classifications: L53, L25, O38

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Based on four different public R&D calls from the Catalan government, this article evaluates the propensity of entrants and young firms to apply for R&D public grants and, as compared to their counterparts, their capacity for obtaining subsides. This analysis is particularly relevant since entrants and young firms encounter greater market difficulties. Our sample contains 22,139 firms and corresponds to a merge of two databases: one from the Catalan agency responsible for promoting private innovation (ACC1Ó) and the other from the Mercantile Register. Merging these databases has two advantages. Firstly, participants and non-participants in the public R&D call (“InnoEmpresa”) are included and, secondly, it provides us with information at firm and project level. The period of observation is between 2006 and 2010, since some explanatory variables are lagged by one period. We apply a two-step methodology. Our results show that entrants and young firms show a lower propensity to apply for R&D subsidies and to obtain R&D public grants. Firm size, exports and participation in a previous call show a positive impact on the likelihood of applying, and firms located in the Barcelona metropolitan area have a greater propensity to apply. Additionally, project quality and R&D cooperative reports presented jointly with other partners have a positive impact on the likelihood of obtaining the R&D subsidy. Finally, firms that have previously obtained an R&D subsidy do not exhibit a greater propensity for obtaining subsequent grants. Keywords: R&D subsidies, entrants and young firms Classification JEL: L53, L25, O38

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Despite the importance of the 4,4'-dithiodipyridine as an electrode modifier on the protein electrochemical studies and as a remarkable bridged-ligand on conducting electronic density in binuclear mixed valence complexes, there is no data available in the literature concerning acid-base behavior of this compound. Aiming to afford such information we undertook the ionization equilibrium study of this ligand. Although two acid species, DTDPH+ and DTDPH2+ have been detected in solution, only the diacid-form was possible to be isolated as a perclorate salt DTDPH2(ClO4)2. The ionization constants for the two step equilibrium processes (pKa1=2.70 and pKa2=4.80) were determined by using the spectrophotometric technique and aqueous solutions of CF3COONa, mu=0,1 mol.L-1 .

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This work discusses sample preparation processes for gas chromatography (GC) based on the technique of extraction through membrane permeation (MPE). The MPE technique may be easily coupled to GC via a relatively simple device, which is a module that holds the membrane and is directly connected to the GC column. The possibility of operational errors due to sample handling is substantially reduced in an MPE-GC system because the sample preparation and the chemical analysis are accomplished as a one-step process. The MPE technique is of relatively wide application as it can be used for aqueous samples, solid samples and gaseous samples. Depending on the type of sample the extraction is performed with the membrane in direct contact with the sample or in contact with its headspace. The MPE-GC technique is very useful in trace analysis, due to the time-dependent enrichment of the analyte. A typical application of MPE-GC is the analysis of VOCs present in water that may be accomplished with detection limits at the low ppb (mugL-1) level.

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This paper estimates the determinants of productivity differentials across urban areas in Spain. To do so we resort to Spanish Social Security administrative data (MCVL) matched with workers’ fiscal information. We use two-step approach that allows us to control for the confounding effects due to the sorting of more productive workers and more productive firms in bigger cities. Our results indicate that city size is a significant determinant of productivity differentials across Spanish urban areas. We estimate an elasticity of urban agglomeration of 3.3%, which is within the range of values already observed in other countries. We also find that the level of human capital, firm size and the level of industrial specialization also matters in order explain productivity differentials across Spanish cities. Keywords: Agglomeration, wages, productivity, city size. JEL codes: R10, R23, J31

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The anodic voltammetric behavior of 4-chlorophenol (4-CF) in aqueous solution has been studied on a Boron-doped diamond electrode using square wave voltammetry (SWV). After optimization of the experimental conditions, 4-CF was analyzed in pure and natural waters using a Britton-Robinson buffer with pH = 6.0 as the supporting electrolyte. Oxidation occurs at 0.80 V vs Ag/AgCl in a two-electron process controlled by adsorption of the species. The detection limits obtained were 6.4 µg L-1 in pure water and 21.5 µg L-1 for polluted water taken from a local creek, respectively. The combination of square wave voltammetry and diamond electrodes is an interesting and desirable alternative for analytical determinations.

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This work presents a study on the dissolution of some commercial monometallic and non-supported deactivated catalysts in HF + H2O2 mixtures (and, eventually, other media) under mild experimental conditions, after a previous oxidation step. The samples were neither crushed nor grinded. The best experimental conditions were dependent on the nature of the support and of the active phase. For example, the Pt/Al2O3 catalyst was dissolved in about 10 minutes, without agitation and heating; however, dissolution of the Pd/Al2O3, Ni/Al2O3, Ni/SiO2, Cu/Al2O3 and V2O5 samples required a temperature of 60 ºC and an agitation of 400 rpm. A careful addition of a NaOH solution allowed a quantitative precipitation of aluminium as criolite (Na3AlF6) or precipitation of Si as Na2SiF6; NaF was obtained as a by-product. As expected, processing of Pd/C, V2O5 and CuO.Cr2O3 samples was relatively simple. Metals recovery from catalysts reached a quantitative level in all samples studied; it is particularly interesting that platinum and palladium could be easily recovered in a single step process, thus separing them from aluminium.

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The identifiability of the parameters of a heat exchanger model without phase change was studied in this Master’s thesis using synthetically made data. A fast, two-step Markov chain Monte Carlo method (MCMC) was tested with a couple of case studies and a heat exchanger model. The two-step MCMC-method worked well and decreased the computation time compared to the traditional MCMC-method. The effect of measurement accuracy of certain control variables to the identifiability of parameters was also studied. The accuracy used did not seem to have a remarkable effect to the identifiability of parameters. The use of the posterior distribution of parameters in different heat exchanger geometries was studied. It would be computationally most efficient to use the same posterior distribution among different geometries in the optimisation of heat exchanger networks. According to the results, this was possible in the case when the frontal surface areas were the same among different geometries. In the other cases the same posterior distribution can be used for optimisation too, but that will give a wider predictive distribution as a result. For condensing surface heat exchangers the numerical stability of the simulation model was studied. As a result, a stable algorithm was developed.

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In recent years, the introduction of the Green Chemistry concepts in undergraduate chemistry classes has been intensively pursued. In this regard, the two-step preparation of Epoxone (an organocatalyst developed by Shi & col.) from commercial D-fructose, through ketalization of vicinal diols followed by oxidation of a sterically congested secondary alcohol, involves important topics in Organic Chemistry and employs inexpensive and nontoxic reagents. The reactions are easy to perform and the products from both steps are readily obtained as crystalline solids after simple procedures, thus facilitating their chemical characterization.

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A two-step experiment is proposed for a third year class in experimental organic chemistry. Over a period of five weeks, the students synthesized calix[4]pyrrole, a receptor that is highly selective for fluoride, and a pyridinium N-phenolate dye. Subsequently, the students used the synthesized compounds to investigate a displacement assay on the basis of the competition in acetonitrile between fluoride and the dye for calix[4]pyrrole. The experiment increased the students' skills in organic synthesis and in the characterization of organic compounds, provided a very attractive and accessible illustration of important supramolecular phenomena, and allowed the study of a chromogenic chemosensor.

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In this work, Doehlert experimental design was used to optimize the Transesterification Double Step Process (TDSP) method of methyl soybean oil biodiesel production which starts with a basic catalysis followed by an acidic catalysis. The conversion values were calculated from NMR spectra. Response surface was used to show the results of the interactions between the variables. This experimental design evaluated variables like catalyst and alcohol amount for the basic catalysis and time and temperature for the acidic catalysis. According to results obtained after Doehlert design application the alcohol amount was the main factor that influenced on the basic catalysis but for the acidic catalysis both time and temperature are important and their effects are opposite. It resulted on excellent conversions for both steps obtaining for the basic catalysis about 100% when was used like optimal conditions catalyst amount equal to 0.40 g and volume of methanol equal to 60 mL and for the acidic catalysis about 99% when was used like optimal conditions temperature of 65 °C and 90 minutes for reaction time.

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A small carbonatite dyke swarm has been identified at Naantali, southwest Finland. Several swarms of shoshonitic lamprophyres are also known along the Archean-Proterozoic boundary in eastern Finland and northwest Russia. These intrusions, along with the carbonatite intrusion at Halpanen, eastern Finland, represent a stage of widespread low-volume mantle-sourced alkaline magmatism in the Svecofennian Domain. Using trace element and isotope geochemistry coupled with precise geochronology from these rocks, a model is presented for the Proterozoic metasomatic evolution of the Fennoscandian subcontinental lithospheric mantle. At ~2.2-2.06 Ga, increased biological production in shallow seas linked to continental rifting, resulted in increased burial rates of organic carbon. Subduction between ~1.93-1.88 Ga returned organic carbon-enriched sediments of mixed Archean and Proterozoic provenance to the mantle. Dehydration reactions supplied water to the mantle wedge, driving arc volcanism, while mica, amphibole and carbonate were brought deeper into the mantle with the subducting slab. The cold subducted slab was heated conductively from the surrounding warm mantle, while pressures continued to gradually increase as a result of crustal thickening. The sediments began to melt in a two stage process, first producing a hydrous alkaline silicate melt, which infiltrated the mantle wedge and crystallised as metasomatic veins. At higher temperatures, carbonatite melt was produced, which preferentially infiltrated the pre-existing metasomatic vein network. At the onset of post-collisional extension, deep fault structures formed, providing conduits for mantle melts to reach the upper crust. Low-volume partial melting of the enriched mantle at depths of at least 110 km led to the formation of first carbonatitic magma and subsequently lamprophyric magma. Carbonatite was emplaced in the upper crust at Naantali at 1795.7 ± 6.8 Ma; lamprophyres along the Archean-Proterozoic boundary were emplaced between 1790.1 ± 3.3 Ma and 1781 ± 20 Ma.