70 research outputs found

    Power, norms and institutional change in the European Union: the protection of the free movement of goods

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    How do institutions of the European Union change? Using an institutionalist approach, this article highlights the interplay between power, cognitive limits, and the normative order that underpins institutional settings and assesses their impact upon the process of institutional change. Empirical evidence from recent attempts to reinforce the protection of the free movement of goods in the EU suggests that, under conditions of uncertainty, actors with ambiguous preferences assess attempts at institutional change on the basis of the historically defined normative order which holds a given institutional structure together. Hence, path dependent and incremental change occurs even when more ambitious and functionally superior proposals are on offer

    Dynamic Scaling and Two-Dimensional High-Tc Superconductors

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    There has been ongoing debate over the critical behavior of two-dimensional superconductors; in particular for high Tc superconductors. The conventional view is that a Kosterlitz-Thouless-Berezinskii transition occurs as long as finite size effects do not obscure the transition. However, there have been recent suggestions that a different transition actually occurs which incorporates aspects of both the dynamic scaling theory of Fisher, Fisher, and Huse and the Kosterlitz-Thouless-Berezinskii transition. Of general interest is that this modified transition apparently has a universal dynamic critical exponent. Some have countered that this apparent universal behavior is rooted in a newly proposed finite-size scaling theory; one that also incorporates scaling and conventional two-dimensional theory. To investigate these issues we study DC voltage versus current data of a 12 angstrom thick YBCO film. We find that the newly proposed scaling theories have intrinsic flexibility that is relevant to the analysis of the experiments. In particular, the data scale according to the modified transition for arbitrarily defined critical temperatures between 0 K and 19.5 K, and the temperature range of a successful scaling collapse is related directly to the sensitivity of the measurement. This implies that the apparent universal exponent is due to the intrinsic flexibility rather than some real physical property. To address this intrinsic flexibility, we propose a criterion which would give conclusive evidence for phase transitions in two-dimensional superconductors. We conclude by reviewing results to see if our criterion is satisfied.Comment: 14 page

    Quorum sensing:Implications on rhamnolipid biosurfactant production

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    Quorum sensing (QS) has received significant attention in the past few decades. QS describes population density dependent cell to cell communication in bacteria using diffusible signal molecules. These signal molecules produced by bacterial cells, regulate various physiological processes important for social behavior and pathogenesis. One such process regulated by quorum sensing molecules is the production of a biosurfactant, rhamnolipid. Rhamnolipids are important microbially derived surface active agents produced by Pseudomonas spp. under the control of two interrelated quorum sensing systems; namely las and rhl. Rhamnolipids possess antibacterial, antifungal and antiviral properties. They are important in motility, cell to cell interactions, cellular differentiation and formation of water channels that Currently, biosurfactants are unable to compete economically with chemically synthesized compounds in the market due to high production costs. Once the genes required for biosurfactant production have been identified, they can be placed under the regulation of strong promoters in nonpathogenic, heterologous hosts to enhance production. The production of rhamnolipids could be increased by cloning both the rhlAB rhamnosyltransferase genes and the rhlRI quorum sensing system into a suitable bacterium such as E. coli or P. putida and facilitate rhamnolipid production. Biosurfactants can also be genetically engineered for different industrial applications assuming there is a strong understanding of both the genetics and the structure-function relationships of each component of the molecule. Genetic engineering of surfactin has already been reported, with recent papers describing the creation of novel peptide structures from the genetic recombination of several peptide synthetases. Recent application of dynamic metabolic engineering strategies for controlled gene expression could lower the cost of fermentation processes by increasing the product formation. Therefore, by integrating a genetic circuit into applications of metabolic engineering the biochemical production can be optimized. Furthermore, novel strategies could be designed on the basis of information obtained from the studies of quorum sensing and biosurfactants produced suggesting enormous practical applications.</p

    Global data set of long-term summertime vertical temperature profiles in 153 lakes

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    peer reviewedClimate change and other anthropogenic stressors have led to long-term changes in the thermal structure, including surface temperatures, deepwater temperatures, and vertical thermal gradients, in many lakes around the world. Though many studies highlight warming of surface water temperatures in lakes worldwide, less is known about long-term trends in full vertical thermal structure and deepwater temperatures, which have been changing less consistently in both direction and magnitude. Here, we present a globally-expansive data set of summertime in-situ vertical temperature profiles from 153 lakes, with one time series beginning as early as 1894. We also compiled lake geographic, morphometric, and water quality variables that can influence vertical thermal structure through a variety of potential mechanisms in these lakes. These long-term time series of vertical temperature profiles and corresponding lake characteristics serve as valuable data to help understand changes and drivers of lake thermal structure in a time of rapid global and ecological change. © 2021, The Author(s)

    The Physics of the B Factories

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