12 resultados para Spillover

em CentAUR: Central Archive University of Reading - UK


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The adsorption of CO has been measured on a 2.5 wt% Pt/TiO2 catalyst using TPD. A somewhat surprising observation is that (i) CO2 is produced, even though oxygen is not dosed into the system, (ii) repeated experiments result in the same amount of CO2 desorption. The results appear to be due to a combination of factors-(i) is due to spillover of CO from the Pt to the TiO2 support, while (ii) is due to the diffusion of Ti3+ into the bulk of the TiO2 crystallite, which effectively removes the surface non-stoichiometry which might otherwise be expected.

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Hydrogen spillover on carbon-supported precious metal catalysts has been investigated with inelastic neutron scattering (INS) spectroscopy. The aim, which was fully realized, was to identify spillover hydrogen on the carbon support. The inelastic neutron scattering spectra of Pt/C, Ru/C, and PtRu/C fuel cell catalysts dosed with hydrogen were determined in two sets of experiments: with the catalyst in the neutron beam and, using an annular cell, with carbon in the beam and catalyst pellets at the edge of the cell excluded from the beam. The vibrational modes observed in the INS spectra were assigned with reference to the INS of a polycyclic aromatic hydrocarbon, coronene, taken as a molecular model of a graphite layer, and with the aid of computational modeling. Two forms of spillover hydrogen were identified: H at edge sites of a graphite layer (formed after ambient dissociative chemisorption of H-2), and a weakly bound layer of mobile H atoms (formed by surface diffusion of H atoms after dissociative chernisorption of H-2 at 500 K). The INS spectra exhibited characteristic riding modes of H on carbon and on Pt or Ru. In these riding modes H atoms move in phase with vibrations of the carbon and metal lattices. The lattice modes are amplified by neutron scattering from the H atoms attached to lattice atoms. Uptake of hydrogen, and spillover, was greater for the Ru containing catalysts than for the Pt/C catalyst. The INS experiments have thus directly demonstrated H spillover to the carbon support of these metal catalysts.

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Knowledge spillover theory of entrepreneurship and the prevailing theory of economic growth treat opportunities as endogenous and generally focus on opportunity recognition by entrepreneurs. New knowledge created endogenously results in knowledge spillovers enabling inventors and entrepreneurs to commercialize it. This article discusses that knowledge spillover entrepreneurship depends not only on ordinary human capital, but more importantly also on creativity embodied in creative individuals and diverse urban environments that attract creative classes. This might result in self-selection of creative individuals into entrepreneurship or enable entrepreneurs to recognize creativity and commercialize it. This creativity theory of knowledge spillover entrepreneurship is tested utilizing data on European cities.

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We examine the black box of creativity, entrepreneurship and economic development by asking about the mechanisms through which creativity can influence economic development in cities. We propose that, like the knowledge spillover theory of entrepreneurship, creativity spillovers occur and can be slowed by a creativity filter. We examine how creativity and entrepreneurship, and creativity and a melting pot environment, interact to influence urban economic development. Using data on 187 cities in 15 European countries for the period 1999–2009, we advance the extant literature by providing evidence on the existence and dynamics of a creativity filter.

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Inelastic neutron scattering spectroscopy has been used to observe and characterise hydrogen on the carbon component of a Pt/C catalyst. INS provides the complete vibration spectrum of coronene, regarded as a molecular model of a graphite layer. The vibrational modes are assigned with the aid of ab initio density functional theory calculations and the INS spectra by the a-CLIMAX program. A spectrum for which the H modes of coronene have been computationally suppressed, a carbon-only coronene spectrum, is a better representation of the spectrum of a graphite layer than is coronene itself. Dihydrogen dosing of a Pt/C catalyst caused amplification of the surface modes of carbon, an effect described as H riding on carbon. From the enhancement of the low energy carbon modes (100-600 cm(-1)) it is concluded that spillover hydrogen becomes attached to dangling bonds at the edges of graphitic regions of the carbon support. (C) 2003 Elsevier Science B.V. All rights reserved.

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Recent research documents the importance of uncertainty in determining macroeconomic outcomes, but little is known about the transmission of uncertainty across such outcomes. This paper examines the response of uncertainty about inflation and output growth to shocks documenting statistically significant size and sign bias and spillover effects. Uncertainty about inflation is a determinant of output uncertainty, whereas higher growth volatility tends to raise inflation volatility. Both inflation and growth volatility respond asymmetrically to positive and negative shocks. Negative growth and inflation shocks lead to higher and more persistent uncertainty than shocks of equal magnitude but opposite sign.

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This study analyzes the regional spatial dynamics of the New York region for a period of roughly twenty years and places the effects of the 9/11 terrorist attacks in the context of longer-term regional dynamics. The analysis reveals that office-using industries are still heavily concentrated in Manhattan despite ongoing decentralization in many of these industries over the last twenty years. Financial services tend to be highly concentrated in Manhattan whereas administrative and support services are the least concentrated of the six major office-using industry groups. Although office employment has been by and large stagnant in Manhattan for at least two decades, growth of output per worker has outpaced the CMSA as well as the national average. This productivity differential is mainly attributable to competitive advantages of office-using industries in Manhattan and not to differences in industry composition. Finally, the zip-code level analysis of the Manhattan core area yielded further evidence of the existence of significant spillover effects at the small-scale level.

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Bangladesh Rural Advancement Committee (BRAC), a non-governmental organisation (NGO), runs a large number of non-formal primary schools in Bangladesh which target out-of-school children from poor families. These schools are well-known for their effectiveness in closing the gender gap in primary school enrolment. On the other hand, registered non-government secondary madrasas (or Islamic schools) today enrol one girl against every boy student. In this article, we document a positive spillover effect of BRAC schools on female secondary enrolment in registered madrasas. Drawing upon school enrolment data aggregated at the region level, we first show that regions that had more registered madrasas experienced greater secondary female enrolment growth during 1999–2003, holding the number of secular secondary schools constant. In this context we test the impact of BRAC-run primary schools on female enrolment in registered madrasas. We deal with the potential endogeneity of placement of BRAC schools using an instrumental variable approach. Controlling for factors such as local-level poverty, road access and distance from major cities, we show that regions with a greater presence of BRAC schools have higher female enrolment growth in secondary madrasas. The effect is much bigger when compared to that on secondary schools.

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This article examines whether a country's economic reforms are affected by reforms adopted by other countries. Our theoretical model predicts that reforms are more likely when factors of production are internationally mobile and reforms are pursued in other economies. Using the change in the Index of Economic Freedom as the measure of market-liberalizing reforms and panel data (144 countries, 1995–2006), we test our model. We find evidence of the spillover of reforms. Moreover, consistent with our model, international trade is not a vehicle for the diffusion of economic reforms; rather the most important mechanism is geographical or cultural proximity.

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Purpose – This paper aims to investigate the influence of public-private partnerships (PPPs) on social and economic conditions in Kazakhstan and Russia from a public economics perspective, namely, through the lens of a market failure and PPPs’ negative externalities. Design/methodology/approach – Drawing on the concept of a market failure and using the externalities perspective, the paper investigates whether partnerships are instrumental in solving market problems, which is illustrated by the evidence from ongoing PPP projects in Kazakhstan and Russia. Findings – Results show that citizens face expansion of monopolistic trends in the service provision and decreased availability of public services. Additionally, the government support to partnerships recreates a negative externality in the form of a higher risk premium on loan interest rates that banks use to finance PPPs. The partnerships’ impact on sustainable development often appears detrimental, as they significantly intensify the struggle between sub-national governments for increased transfers from the national budget. Practical implications – The government agencies must incorporate the appraisal of the PPP externalities and their effects on the society in the decision-making regarding the PPP formation. Originality/value – The authors suggest that, although government is interested in PPPs’ positive externalities, in reality many negative externalities may offset the positive spillover effects. As a result, the partnerships’ contributions to economic and social sustainability remain controversial. Extending the value-for-money concept to incorporate the assessment of PPP externalities might significantly enhance the partnership conceptualisation by more comprehensive and accurate assessment of PPPs’ economic and social value.

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Purpose – The purpose of this paper is to investigate the effect of the crisis on the pricing of asset quality attributes. This paper uses sales transaction data to examine whether flight from risk phenomena took place in the US office market during the financial crisis of 2007-2009. Design/methodology/approach – Hedonic regression procedures are used to test the hypothesis that the spread between the pricing of low-quality and high-quality characteristics increased during the crisis period compared to the pre-crisis period. Findings – The results of the hedonic regression models suggest that the price spread between Class A and other properties grew significantly during the downturn. Research limitations/implications – Our results are consistent with the hypothesis of an increased price spread following a market downturn between Class A and non-Class A offices. The evidence suggests that the relationships between the returns on Class A and non-Class A assets changed during the period of market stress or crisis. Practical implications – These findings have implications for real estate portfolio construction. If regime switches can be predicted and/or responded to rapidly, portfolios may be rebalanced. In crisis periods, portfolios might be reweighted towards Class A properties and in positive market periods, the reweighting would be towards non-Class A assets. Social implications – The global financial crisis has demonstrated that real estate markets play a crucial role in modern economies and that negative developments in these markets have the potential to spillover and create contagion for the larger economy, thereby affecting jobs, incomes and ultimately people’s livelihoods. Originality/value – This is one of the first studies that address the flight to quality phenomenon in commercial real estate markets during periods of financial crisis and market turmoil.