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Clear Shift (clear + shift)
Selected AbstractsBIODIVERSITY RESEARCH: Native-exotic species richness relationships across spatial scales and biotic homogenization in wetland plant communities of Illinois, USADIVERSITY AND DISTRIBUTIONS, Issue 5 2010Hua Chen Abstract Aim, To examine native-exotic species richness relationships across spatial scales and corresponding biotic homogenization in wetland plant communities. Location, Illinois, USA. Methods, We analysed the native-exotic species richness relationship for vascular plants at three spatial scales (small, 0.25 m2 of sample area; medium, 1 m2 of sample area; large, 5 m2 of sample area) in 103 wetlands across Illinois. At each scale, Spearman's correlation coefficient between native and exotic richness was calculated. We also investigated the potential for biotic homogenization by comparing all species surveyed in a wetland community (from the large sample area) with the species composition in all other wetlands using paired comparisons of their Jaccard's and Simpson's similarity indices. Results, At large and medium scales, native richness was positively correlated with exotic richness, with the strength of the correlation decreasing from the large to the medium scale; at the smallest scale, the native-exotic richness correlation was negative. The average value for homogenization indices was 0.096 and 0.168, using Jaccard's and Simpson's indices, respectively, indicating that these wetland plant communities have been homogenized because of invasion by exotic species. Main Conclusions, Our study demonstrated a clear shift from a positive to a negative native-exotic species richness relationship from larger to smaller spatial scales. The negative native-exotic richness relationship that we found is suggested to result from direct biotic interactions (competitive exclusion) between native and exotic species, whereas positive correlations likely reflect the more prominent influence of habitat heterogeneity on richness at larger scales. Our finding of homogenization at the community level extends conclusions from previous studies having found this pattern at much larger spatial scales. Furthermore, these results suggest that even while exhibiting a positive native-exotic richness relationship, community level biotas can/are still being homogenized because of exotic species invasion. [source] Mechanical Characterization of Particulate Aluminum Foams,Strain-Rate, Density and Matrix Alloy versus Adhesive EffectsADVANCED ENGINEERING MATERIALS, Issue 7 2010Dirk Lehmhus Abstract The study evaluates mechanical properties of APM particulate aluminum foams built up from adhesively bonded Al foam spheres. Foams of matrix alloy AlSi10 are compared, with PM AlSi7 foams used as reference. The influence of density is studied both for quasi-static and dynamic compressive loading in a range from ,0.35 to 0.71,g,cm,3. The effect of varying the bonding agent is evaluated for a single density and both strain rate levels by replacing the standard, high-strength epoxy-based adhesive with a polyamide of greatly increased ductility. The result is a clear shift of fracture events to higher strain levels, as well as the introduction of a strain-rate dependency of strength. [source] Hydrolysis and microbial community analyses in two-stage anaerobic digestion of energy cropsJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2007D.G. Cirne Abstract Aims:, The roles of the diverse populations of micro-organisms responsible for biodegradation of organic matter to form methane and carbon dioxide are rudimentarily understood. To expand the knowledge on links between microbial communities and the rate limiting, hydrolytic stage of two-stage biogas production from energy crops, this study was performed. Methods and Results:, The process performance and microbial communities (as determined by fluorescence in situ hybridization) in two separate two-stage batch digestions of sugar beets and grass/clover were studied. The microbial populations developed in the hydrolytic stage of anaerobic digestion of beets and grass/clover showed very few similarities, despite that the hydrolysis dynamics were similar. In both substrates, the solubilization of organic material was rapid for the first 10 days and accompanied by a build-up of volatile fatty acids (VFAs) and lactate. Between days 10 and 15, VFA and lactate concentrations decreased, as did the solubilization rates. For both substrates, Archaea started to appear in the hydrolytic stage between days 10 and 15, and the fraction of Bacteria decreased. The major bacterial group detected in the leachate fraction for beets was Alphaproteobacteria, whereas for grass/clover it was Firmicutes. The number of cells that bound to probes specifically targeting bacteria with cellulolytic activity was higher in the digestion of grass than in the digestion of beet. Conclusions:, This study allowed the identification of the general bacterial groups involved, and the identification of a clear shift in the microbial population when hydrolysis rate became limiting for each of the substrates investigated. Significance and Impact of the Study:, The findings from this study could be considered as a first step towards the development of strategies to stimulate hydrolysis further and ultimately increasing the methane production rates and yields from reactor-based digestion of these substrates. [source] Temporal variability in marine feeding of sympatric Arctic charr and sea troutJOURNAL OF FISH BIOLOGY, Issue 3 2007A. H. Rikardsen The marine feeding pattern of anadromous brown trout (sea trout) Salmo trutta and Arctic charr Salvelinus alpinus was studied during June to August in 1992,1993 and 2000,2004 in a fjord in northern Norway. In general sea trout fed proportionally more on fishes than on crustaceans and insects (81, 1 and 18% by mass, respectively) by comparison with Arctic charr (52, 25 and 22% by mass, respectively). Herring Clupea harengus dominated the total fish diet of both species, but the Arctic charr also fed significantly on gadoids and sandlance Ammodytes spp. While sea trout became virtually all piscivorous at fork lengths (LF) ,250 mm, the Arctic charr was ,400 mm LF before shifting totally to a fish diet. Despite annual variation in diet and forage ratios, there was a clear shift in diet from 1992,1993 to 2000,2004. Sandlance and different crustaceans constituted most of the diet during the initial period with a shift towards gadoids and especially herring during the latter period. This shift seemed to be associated with a high abundance of herring larvae during the latter sampling period, indicating a preferential selection on herring when present, particularly by sea trout. Furthermore, an index indicated dietary overlap in years with intensive feeding on herring of both species, and usually differences in the trophic ecology during years feeding mostly on other prey species. In combination, it was hypothesized that the two species reflect the type of marine prey present within a fjord system over time, and therefore provide an index of variation in the production and biological diversity of their potential prey within fjords. [source] Ontogenetic induced shifts in the ecology of sunbleak Leucaspius delineatus during early developmentJOURNAL OF FISH BIOLOGY, Issue 2005A. C. Pinder Using the non-native sunbleak Leucaspius delineatus as a model, the relationship between ontogeny and ecology was studied with a view to identifying specific morphological and physiological processes involved in influencing ecological niche shifts. Following a predefined saltatory model for the early ontogeny of sunbleak, field studies examined the temporal use of microhabitat, diet and morphological changes throughout early development. Following a dramatic shift in both morphology and ecology between the free embryo phase and the larval period, habitat use and diet showed little change during the larval period, with habitat use confined to marginal, vegetated areas and prey items associated with these habitats well represented in the diet. During the final larval step (L5), transition to the juvenile period resulted in the stabilization of relative growth, acquisition of the adult morphotype and was associated with a clear shift in diet and habitat use. During this period, sunbleak moved for the first time into open, deeper water, away from the banks, and utilized a similar range of food items to the adults. Specific relationships between form and function are further discussed. [source] Size-dependent Raman and infrared studies of PbSe nanoparticlesJOURNAL OF RAMAN SPECTROSCOPY, Issue 9 2008F. S. Manciu Abstract Micro-probe Raman and far-infrared absorption spectroscopies were used to prove the existence of optical phonon modes of PbSe nanoparticles prepared by colloidal chemistry and preliminarily characterized by transmission electron microscopy. To the best of our knowledge, this is the first time that evidence of the surface phonon (SP) mode by Raman spectroscopy has been experimentally observed. The wavenumber of the SP mode is consistent with its prediction by a dielectric continuum model. While for different PbSe nanoparticle sizes the observed SP mode does not show any obvious change in its position, there is a clear shift by approximately 4 cm,1 toward higher wavenumber in the appearance of the LO(,) in the Raman spectra from the 3 nm to the 7 nm PbSe nanoparticles. Far-infrared measurements demonstrate the presence of the transverse optical TO(,) and of the coupled phonon modes. Copyright © 2008 John Wiley & Sons, Ltd. [source] Reclaiming Legitimacy in ChinaPOLITICS & POLICY, Issue 3 2010HEIKE HOLBIG The contemporary politics of China reflect an ongoing effort by the ruling Chinese Communist Party (CCP) to reclaim the right to rule in light of the consequences of economic development, international pressures, and historical change. China's regime stands out within the Asian region for its success in the effort of adapting to change and ensuring its continuity. Focusing on changes in China's elite discourse during the reform period and particularly during the last decade, the aim of this article is to elaborate the relative importance of various sources of legitimacy as they are shifting over time, as well as inherent dilemmas and limitations. There is evidence of an agile, responsive, and creative party effort to relegitimate the postrevolutionary regime through economic performance, nationalism, ideology, culture, governance, and democracy. At the same time, the study finds a clear shift in emphasis from an earlier economic-nationalistic approach to a more ideological-institutional approach. La política contemporánea China refleja un esfuerzo sostenido del Partido Comunista Chino por continuar ejerciendo el derecho de gobernar a la luz de las consecuencias del desarrollo económico, las presiones internacionales, y el cambio histórico. El régimen Chino se destaca dentro de la región de Asia por su éxito en el esfuerzo de adaptarse al cambio y asegurar su continuidad. Centrándonos en los cambios en el discurso de la elite China durante el periodo de reforma y particularmente durante la última década, el objetivo de este artículo es el de detallar la relativa importancia de las diferentes fuentes de legitimidad y sus variaciones en el tiempo, así como los dilemas y limitaciones inherentes. Existe evidencia de un esfuerzo ágil, sensible y creativo para relegitimar el régimen post-revolucionario a partir del desempeño económico, el nacionalismo, la ideología, la cultura, un buen gobierno, y la democracia. De la misma forma, este estudio encuentra un cambio claro en el énfasis del régimen de un enfoque económico-nacionalista a uno ideológico-institucional. [source] Changing Perceptions of Non-Consensual Sex Crime: The Mediation of a Local NewspaperTHE HOWARD JOURNAL OF CRIMINAL JUSTICE, Issue 5 2009KEITH SOOTHILL Abstract: This article aims to consider all cases of non-consensual sex crime involving a court appearance that were reported in a local newspaper, the Lancaster Guardian, over a period of 120 years (1860,1979). Searching over 6,000 editions of a local newspaper, there are huge shifts in the outcome of non-consensual cases over the 120 years. There is evidence of a lively direct interest from the local populace in some of the early cases, but it is only since the Second World War that more sustained coverage of cases are featured in the newspaper. There is a clear shift over time in the type of cases that receive more media attention. [source] Comparison of 1- and 2-day protocols for myocardial SPECT: a Monte Carlo studyCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 4 2005H. H. El-Ali Summary Background:, Myocardial perfusion single-photon emission computed tomography (SPECT) is carried out by combining a rest and a stress study that are performed either on one day or two separate days. A problem when performing the two studies on 1 day is that the residual activity from the first study contributes to the activity measured in the second study. Aim:, Our aim was to identify and evaluate trends in the quantification parameters of myocardial perfusion images as a function of separation time between rest and stress. Methods:, A digital phantom was used for the generation of heart images and a Monte Carlo-based scintillation camera program was used to simulate SPECT projection images. In our simulations, the rest images were normal and the stress images included lesions of different types and localization. Two programs for quantification of myocardial perfusion images were used to assess the different images in an automated and objective way. Results:, The summed difference scores observed with the 2-day protocol were 3 ± 1 (mean ± SD) higher for AutoQUANT and 2 ± 1 higher for 4D-MSPECT compared with those observed with the 1-day protocol. The extent values were 2% points higher for the 2-day protocol compared with the 1-day protocol for both programs. Conclusions:, There are differences in the quantitative assessment of perfusion defects depending on the type of protocol used. The contribution of residual activity is larger when a 1-day protocol is used compared with the 2-day protocol. The differences, although small, are of a magnitude that results in a clear shift in quantification parameters. [source] | ||||||||||