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Selected AbstractsThe Impact of Advanced Technology Adoption on Wage Structures: Evidence from Taiwan Manufacturing FirmsECONOMICA, Issue 271 2001Jin-Tan Liu We examine the impact of advanced technology adoption on wage and employment structures in Taiwan. Using a survey of manufacturing firms that provides direct information on the use of advanced technologies, we find that firms using more advanced technologies pay higher wages to both non-production and production workers and employ higher fractions of non-production workers. Controlling for the possible endogeneity of technology adoption suggests that the estimated impact of new technologies on wages is downward-biased and that the effect on production workers' wages may be minimal. [source] Life-history strategies in freshwater macroinvertebratesFRESHWATER BIOLOGY, Issue 9 2008WILCO C. E. P. VERBERK Summary 1Explaining spatial and temporal differences in species assemblages is a central aim of ecology. It requires a sound understanding of the causal mechanisms underlying the relationship of species with their environment. A species trait is widely acknowledged to be the key that links pattern and process, although the enormous variety of traits hampers generalization about which combination of traits are adaptive in a particular environment. 2In three steps, we used species traits to match species and environment, and chose lentic freshwater ecosystems to illustrate our approach. We first identified key environmental factors and selected the species traits that enable the organism to deal with them. Secondly, we investigated how investments in these traits are related (e.g. through trade-offs). Thirdly, we outlined 13 life-history strategies, based on biological species traits, their interrelations known from life-history theory and their functional implications. 3Species traits and environmental conditions are connected through life-history strategies, with different strategies representing different solutions to particular ecological problems. In addition, strategies may present an integrated response to the environment as they are based on many different traits and their interrelationships. The presence and abundance of (species exhibiting) different life-history strategies in a location may therefore give direct information about how a particular environment is experienced by the species present. 4Life-history strategies can be used to (i) explain differences in species assemblages either between locations or in different periods; (ii) compare waterbodies separated by large geographical distances, which may comprise different regional species pools or span species distribution areas and (iii) reduce often very complex, biodiverse assemblages into a few meaningful, easily interpretable relationships. [source] Probing the interaction forces between hydrophobic peptides and supported lipid bilayers using AFMJOURNAL OF MOLECULAR RECOGNITION, Issue 6 2007Guillaume Andre Abstract Despite the vast body of literature that has accumulated on tilted peptides in the past decade, direct information on the forces that drive their interaction with lipid membranes is lacking. Here, we attempted to use atomic force microscopy (AFM) to explore the interaction forces between the Simian immunodeficiency virus peptide and phase-separated supported bilayers composed of various lipids, i.e. dipalmitoylphosphatidylcholine, dioleoylphosphatidylcholine, dioleoylphosphatidic acid and dipalmitoylphosphatidylethanolamine. Histidine-tagged peptides were attached onto AFM tips terminated with nitrilotriacetate and tri(ethylene glycol) groups, an approach expected to ensure optimal exposure of the C-terminal hydrophobic domain. Force,distance curves recorded between peptide-tips and the different bilayer domains always showed a long-range repulsion upon approach and a lack of adhesion upon retraction, in marked contrast with the hydrophobic nature of the peptide. To explain this unexpected behaviour, we suggest a mechanism in which lipids are pulled out from the bilayer due to strong interactions with the peptide-tip, in agreement with the very low force needed to extract lipids from supported bilayers. Copyright © 2007 John Wiley & Sons, Ltd. [source] Excess thermodynamic properties in liquid binary mixturesJOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2008F. Aliotta Abstract Excess volumes and adiabatic compressibility have been measured in several binary liquid mixtures to answer the question whether structural information can be gained through the analysis of the concentration dependence of the excess quantities. The obtained results are compared with independent indications from Raman spectroscopy, which is able to probe directly the occurrence and the nature of effective intermolecular interactions. Some doubts have arisen against the usual approach adopted for estimating the excess quantities and about the adequacy of the usual assumptions for the reference ideal behaviours. In particular, it is shown how excess compressibility can result just from statistical effects also in absence of any excess volume contribution. The leading idea is supported by the comparison of the experimental data with the results from a naive model for binary mixtures of hard spheres. The model turns out to be able to produce a very wide spectrum of structural and thermodynamic behaviours depending on the values of its parameters and on the nature (additive or non-additive) of the hard-sphere potential. A discussion is proposed on the re-evaluation of excess thermodynamic data and on their ability in providing direct information on intermolecular interactions. Copyright © 2008 John Wiley & Sons, Ltd. [source] The Economics of an Efficient Reliance on Biomass, Carbon Capture and Carbon Sequestration in a Kyoto-style Emissions Control EnvironmentOPEC ENERGY REVIEW, Issue 3 2001Gary W. Yohe This note employs the economics paradigm to sort through the complications of relying simultaneously on biomass fuels, carbon capture with active sequestration and passive carbon sequestration to meet Kyoto-style carbon emission limits. It does so by exploiting the structure of a tax cum repurchase scheme for carbon. Under such a scheme, the carbon content of fossil fuel should be taxed at the point of purchase at a price that matches the shadow price of the carbon emission limit, but carbon embedded in biomass fuel should go un-taxed. The price of biomass fuel would, though, have to reflect the marginal cost of any externalities it might cause and the opportunity cost of its land-use requirements. Captured carbon could be repurchased at a price equal to the shadow price of carbon, net of the cost of active sequestration, itself the sum of private and social marginal costs. Finally, the price of the passive sequestration of carbon should equal the shadow price of carbon, net of the opportunity cost of setting those resources aside. Since a marketable permit system would support direct estimates of the requisite shadow price of carbon, such a system would also provide direct information about base prices for the tax cum repurchase scheme. To support long-term investment in biomass supply and sequestration, though, changes over time in emission limits must be accomplished in a smooth and predictable manner. [source] Time-resolved structural studies of protein reaction dynamics: a smorgasbord of X-ray approachesACTA CRYSTALLOGRAPHICA SECTION A, Issue 2 2010Sebastian Westenhoff Proteins undergo conformational changes during their biological function. As such, a high-resolution structure of a protein's resting conformation provides a starting point for elucidating its reaction mechanism, but provides no direct information concerning the protein's conformational dynamics. Several X-ray methods have been developed to elucidate those conformational changes that occur during a protein's reaction, including time-resolved Laue diffraction and intermediate trapping studies on three-dimensional protein crystals, and time-resolved wide-angle X-ray scattering and X-ray absorption studies on proteins in the solution phase. This review emphasizes the scope and limitations of these complementary experimental approaches when seeking to understand protein conformational dynamics. These methods are illustrated using a limited set of examples including myoglobin and haemoglobin in complex with carbon monoxide, the simple light-driven proton pump bacteriorhodopsin, and the superoxide scavenger superoxide reductase. In conclusion, likely future developments of these methods at synchrotron X-ray sources and the potential impact of emerging X-ray free-electron laser facilities are speculated upon. [source] Characterization of the impact of geostationary clear-sky radiances on wind analyses in a 4D-Var contextTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 644 2009C. Peubey The impact of geostationary clear-sky radiances (CSRs) on 4D-Var wind analyses has been investigated by running a set of observing system experiments. Analysis scores have been calculated to measure the ability of individual satellite datasets to improve the wind analysis, starting from a no-satellite baseline. In this context, the assimilation of CSRs from the two water-vapour channels on Meteosat-9 has been found to improve the wind analysis throughout the troposphere, with the strongest signal at 300 and 500 hPa. Indeed, for the Northern Hemisphere and the Tropics, the CSR impact at these levels exceeds that of the Meteosat-9 atmospheric motion vectors (AMVs), the sampling of the latter in the assimilation being rather limited. Conversely, the impact of AMVs exceeds that of CSRs in the lower troposphere, where the latter provide very little direct information. This demonstrates the complementarity of the two datasets in the operational 4D-Var wind analysis. The mechanisms through which the assimilation of CSRs can impact wind analyses have been isolated. The dominant effect is that of humidity-tracer advection, by which the wind field is adjusted in order to fit observed humidity features via the minimization of the 4D-Var cost function. Other mechanisms, such as balance constraints and the cycling of the forecast model that links the humidity and wind variables, have been found to play a minor role. The benefit of having frequent CSR images within the assimilation window has also been demonstrated. Copyright © 2009 Royal Meteorological Society [source] Conformational change of the AcrR regulator reveals a possible mechanism of inductionACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 7 2008Ruoyu Gu The Escherichia coli AcrR multidrug-binding protein represses transcription of acrAB and is induced by many structurally unrelated cytotoxic compounds. The crystal structure of AcrR in space group P2221 has been reported previously. This P2221 structure has provided direct information about the multidrug-binding site and important residues for drug recognition. Here, a crystal structure of this regulator in space group P31 is presented. Comparison of the two AcrR structures reveals possible mechanisms of ligand binding and AcrR regulation. [source] Productivity, exporting, and the learning-by-exporting hypothesis: direct evidence from UK firmsCANADIAN JOURNAL OF ECONOMICS, Issue 2 2008Gustavo Crespi Abstract., Case studies suggest exporters learn from clients. Econometric evidence is mixed. We use firm-level panel data on exporting and productivity with direct information on learning sources, including clients. We find: (a) firms who exported in the past are likely to learn more from clients (relative to other sources); (b) firms who learned from clients in the past are more likely to have faster productivity growth; (c) the reverse is not the case; that is, past productivity growth is not associated with more learning from clients and past learning from clients is not associated with more exporting. These results are consistent with the learning-by-exporting hypothesis. Des études de cas suggèrent que les exportateurs apprennent beaucoup de leurs clients. Les résultats de l'analyse économique sont moins concluants. On utilise des données de panel au niveau de la firme à propos des activités d'exportation et de la productivité, ainsi que des informations directes sur les sources d'apprentissage, y compris les clients. On découvre que (a) les firmes qui ont exporté dans le passé sont davantage susceptibles d'apprendre le plus de leurs clients (par rapport aux autres sources); (b) les firmes qui ont appris de leurs clients dans le passé sont davantage susceptibles d'avoir une croissance de productivité plus rapide; (c) le contraire n'est pas le cas, i.e., qu'une croissance de productivité dans le passé n'est pas associée avec plus d'apprentissage des clients, et que l'apprentissage dans le passé n'est pas associéà davantage d'exportation. Voilà qui est compatible avec l'hypothèse de l'apprentissage-par-l'exportation. [source] | |||||||||||||