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| 2. |
- Arnold, Michelle, et al.
(författare)
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Productivity of innovation in biofuel technologies
- 2019
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Ingår i: Energy Policy. - : Elsevier. - 0301-4215 .- 1873-6777. ; 124, s. 54-62
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Tidskriftsartikel (refereegranskat)abstract
- Biofuels are a regular focus of public policy. The productivity of innovation in biofuel technologies is rarely addressed either in research or policy. Yet as innovation in any field grows complex and costly it can experience reductions in productivity and diminishing returns to investments. We examine here the productivity of investments in the technologies used to produce biofuels, using data from the U.S. Patent and Trademark Office. The results show that the productivity of innovation in biofuel technologies is declining. Continuation of this trend will in time force reductions in research investments in biofuel technologies. We discuss policy approaches to address declining returns to research investments.
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| 3. |
- Bettencourt, Luis M. A., et al.
(författare)
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Invention in the city : Increasing returns to patenting as a scaling function of metropolitan size
- 2007
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Ingår i: Research Policy. - : Elsevier. - 0048-7333 .- 1873-7625. ; 36:1, s. 107-120
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the relationship between patenting activity and the population size of metropolitan areas in the United States over the last two decades (1980-2001). We find a clear superlinear effect, whereby new patents are granted disproportionately in larger urban centers, thus showing increasing returns in inventing activity with respect to population size. We characterize this relation quantitatively as a power law with an exponent larger than unity. This phenomenon is commensurate with the presence of larger numbers of inventors in larger metropolitan areas, which we find follows a quantitatively similar superlinear relationship to population, while the productivity of individual inventors stays essentially constant across metropolitan areas. We also find that structural measures of the patent co-authorship network although weakly correlated to increasing rates of patenting, are not enough to explain them. Finally, we show that R&D establishments and employment in other creative professions also follow superlinear scaling relations to metropolitan population size, albeit possibly with different exponents.
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| 4. |
- Bettencourt, Luís M. A., et al.
(författare)
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Urban scaling and its deviations : Revealing the structure of wealth, innovation and crime across cities
- 2010
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Ingår i: PLOS ONE. - : PLOS. - 1932-6203. ; 5:11
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Tidskriftsartikel (refereegranskat)abstract
- With urban population increasing dramatically worldwide, cities are playing an increasingly critical role in human societies and the sustainability of the planet. An obstacle to effective policy is the lack of meaningful urban metrics based on a quantitative understanding of cities. Typically, linear per capita indicators are used to characterize and rank cities. However, these implicitly ignore the fundamental role of nonlinear agglomeration integral to the life history of cities. As such, per capita indicators conflate general nonlinear effects, common to all cities, with local dynamics, specific to each city, failing to provide direct measures of the impact of local events and policy. Agglomeration nonlinearities are explicitly manifested by the superlinear power law scaling of most urban socioeconomic indicators with population size, all with similar exponents (~1.15). As a result larger cities are disproportionally the centers of innovation, wealth and crime, all to approximately the same degree. We use these general urban laws to develop new urban metrics that disentangle dynamics at different scales and provide true measures of local urban performance. New rankings of cities and a novel and simpler perspective on urban systems emerge. We find that local urban dynamics display long-term memory, so cities under or outperforming their size expectation maintain such (dis)advantage for decades. Spatiotemporal correlation analyses reveal a novel functional taxonomy of U.S. metropolitan areas that is generally not organized geographically but based instead on common local economic models, innovation strategies and patterns of crime.
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| 5. |
- Drennan, Matthew P., et al.
(författare)
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Unit root tests of sigma income convergence across US metropolitan areas
- 2004
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Ingår i: Journal of Economic Geography. - : Oxford University Press. - 1468-2702 .- 1468-2710. ; 4:5, s. 583-595
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Tidskriftsartikel (refereegranskat)abstract
- The standard deviation of metropolitan per capita personal income (PCPI) and metropolitan average wage per job (AWPJ) provide straightforward indicators of unconditional sigma convergence for metropolitan economies within the United States. Using data for all metropolitan areas in the continental United States for the period 1969-2001, we tested for the unconditional sigma income convergence hypothesis by applying two unit root tests to the time series of the two standard deviations. Our results indicate that the time series can be described as random walks with drift, thereby supporting the claim that income divergence among metropolitan economies is not decreasing.
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| 6. |
- Drennan, Matthew, et al.
(författare)
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Sectoral shares, specialisation and metropolitan wages in the Unites States, 1969-96
- 2002
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Ingår i: Urban Studies. - : Sage Publications. - 0042-0980 .- 1360-063X. ; 39:7, s. 1129-1142
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the effect of specialisation upon the level of metropolitan wage per worker. Specialisation is measured by the share of metropolitan earnings in each of five traded goods and services sectors. Sectoral specialisations are assumed to be determinants of location-specific productivity, which in turn is treated as a term in a metropolitan production function. Panel data are used for estimating that production function for 313 metropolitan areas in the US, over the long period 1969-96 and two shorter periods. We find that some specialisations raise average metropolitan wages, some lower it and some have no effect, and that the effects of specialisation differ by time-period.
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| 7. |
- Fragkias, Michail, et al.
(författare)
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Does Size Matter? Scaling of CO2 Emissions and U.S. Urban Areas
- 2013
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Ingår i: PLOS ONE. - : PLOS. - 1932-6203. ; 8:6
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Tidskriftsartikel (refereegranskat)abstract
- Urban areas consume more than 66% of the world's energy and generate more than 70% of global greenhouse gas emissions. With the world's population expected to reach 10 billion by 2100, nearly 90% of whom will live in urban areas, a critical question for planetary sustainability is how the size of cities affects energy use and carbon dioxide (CO2) emissions. Are larger cities more energy and emissions efficient than smaller ones? Do larger cities exhibit gains from economies of scale with regard to emissions? Here we examine the relationship between city size and CO2 emissions for U.S. metropolitan areas using a production accounting allocation of emissions. We find that for the time period of 1999-2008, CO2 emissions scale proportionally with urban population size. Contrary to theoretical expectations, larger cities are not more emissions efficient than smaller ones.
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| 10. |
- Holt, Thomas J., et al.
(författare)
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Examining the social networks of malware writers and hackers
- 2012
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Ingår i: International Journal of Cyber Criminology. - : International Journal of Cyber Criminology. - 0974-2891. ; 6:1, s. 891-903
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Tidskriftsartikel (refereegranskat)abstract
- A substantive body of research has emerged exploring the social dynamics and subculture of computer hacking. Few, however, have considered the structure of social networks in the hacker community due in part to the lack of visible information about active hackers or malware writers. Our research focuses on the rarely studied subject of underground networks of computer hackers. Thus, this study explores the social networks of a group of Russian hackers using publicly accessible data to understand the nature of social relationships and the ways that they affect information sharing and action. The findings demonstrate that there are a limited number of highly skilled hackers relative to those with some knowledge of computers. Additionally, those hackers with substantive technical skills are centrally located within friendship networks and are the focus of greater attention overall. The impact of these findings for our understanding of computer hacking, and peer networks generally are considered in detail.
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