921 resultados para AMPLIFICATION


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Harold Pinter's artistic achievements and political activities have made him a celebrity and, like other processes of enlargement or amplification, fame can distort that to which it draws attention.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We examine the trade credit linkages among firms within a supply chain to reckon the effect of such linkages on the propagation of liquidity shocks from downstream to upstream firms. We choose a sample appropriate for this task, consisting of a large data set of Italian firms from the textile industry, a well known example of a comprehensive manufacturing cluster featuring a large number of small and specialized firms at each level of the supply chain. The results of the analysis indicate that the level of trade credit that firms provide to their suppliers is positively related to the level of trade credit granted to their clients: when the level of trade credit granted to clients divided by sales goes up by 1, the level of trade credit provided to suppliers divided by cost-of goods-sold goes up by an amount that varies between 0,22 and 0,52. Since all firms along the chain are linked by trade credit relationships, an increase in the level of trade credit granted by wholesalers generates a liquidity cascade throughout the chain. We designate the overall increase in the level of trade credit among all firms in the chain as a result of a unitary impulse in the level of trade credit granted by wholesalers as the multiplier effect of trade credit for the industry chain. We estimate such multiplier to vary between 1.28 and 2.04. We also investigate the effect of final demand on the level of trade credit sourced by firms at various levels of the chain and, in particular, whether such effect is amplified for firms further up in the chain as a result of liquidity propagation via trade credit linkages. We uncover evidence of such amplification when the links of liquidity transmission along the chain are individually modeled and estimated. An unitary increase in wholesalers’ sales is found to produce an effect on trade payables among firms at the top of the chain (i.e., Preparers and Spinners) that is more than twice as big as the corresponding effect among firms at the bottom of the chain (i.e., Wholesalers).

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Two media were developed which specifically allow the cultivation of Bacillus thuringiensis while it is in the vegetative as opposed to the spore form. Using these media B. thuringiensis was shown conclusively for the first time to exist in an active form on the phylloplane. The profile of its appearance in vegetative and spore form was followed over a growing season on clover (Trifolium hybridum) in the field. Three simultaneous and sudden rises and declines of both spore and vegetative cell densities were observed. The most common other spore-former on these leaves was Bacillus cereus but the fluctuations in appearance of these two very closely related species were not co-incident. Using specific PCR primers a considerable diversity of cry toxin gene types was found in isolates that had been recovered in vegetative form ([`]vegetative isolates') with the majority possessing multiple [delta]-endotoxin genes while some had only one of those tested. Bioassays against a lepidopteran insect of purified [delta]-endotoxins showed that they were no more potent than those from a laboratory-adapted strain. PCR primers for an internal region of the vip3A gene produced amplification in 70% of the vegetative isolates compared to 25% of the laboratory-adapted strains tested.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The Continuous Plankton Recorder (CPR) survey has collected plankton samples from regular tracks across the world's oceans for almost 70 y. Over 299,000 spatially extensive CPR samples are archived and stored in buffered formalin. This CPR archive offers huge potential to study changes in marine communities using molecular data from a period when marine pollution, exploitation and global anthropogenic impact were much less pronounced. However, to harness the amount of data available within the CPR archive fully, it is necessary to improve techniques of larval identification, to genus and species preferably, and to obtain genetic information for historical studies of population ecology. To increase the potential of the CPR database this paper describes the first extraction, amplification by the polymerase chain reaction and utilization of a DNA sequence (mitochondrial 16S rDNA) from a CPR sample, a formalin fixed larval sandeel.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In the mid-1980s the North Sea ecosystem experienced a climate-induced regime shift that has favoured decapods and detritivores in the benthos and jellyfish in the plankton over commercial fisheries. Here, we investigate changes among the Decapoda in the North Sea plankton over the last 60 yr. Decapods are important predators in the plankton and the benthos where they can influence productivity and structure communities. In the North Sea it has been suggested that a climate-driven increase in decapod abundance has been important in propagating the climate signal through the North Sea food web. We show that climate-induced changes in the Decapoda in the central and southern North Sea include the presence of new warm-water taxa, changes in the abundance and proportions of commercial species of shrimp, and an earlier occurrence of decapod larvae in the plankton compared with the period 1981–1983. Notable amongst the warm-water taxa appearing in the North Sea is the predatory swimming crab Polybius henslowii that can swarm in large numbers when conditions are favourable and that is known to exhibit range shifts in response to fluctuations in hydroclimatic forcing. We suggest that climate-induced changes among North Sea decapods have played an important role in the trophic amplification of a climate signal and the development of the new North Sea dynamic regime. Understanding these changes is likely to be imperative for a successful ecosystem-based approach to the future management of North Sea fisheries at a time of climate change.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Acartia and Paracartia species, often known to co-occur, can exhibit complex life cycles, including the production of resting eggs. Studying and understanding their population dynamics is hindered by the inability to identify eggs and early developmental stages using morphological techniques. We have developed a simple molecular technique to distinguish between the three species of the Acartiidae family (Acartia clausi, A. discaudata and Paracartia grani) that co-occur in the Thau lagoon (43�250N; 03�400E) in southern France. Direct amplification of a partial region of the mitochondrial cytochrome oxidase I gene by polymerase chain reaction and subsequent restriction fragment length polymorphism results in a unique restriction profile for each species. The technique is capable of determining the identity of individual eggs, including resting eggs retrieved from sediment samples, illustrating its application in facilitating population dynamic studies of this ubiquitous and important member of the zooplankton community.