933 resultados para trunk wood
Resumo:
The potential risk of agricultural pesticides to mammals typically depends on internal concentrations within individuals, and these are determined by the amount ingested and by absorption, distribution, metabolism, and excretion (ADME). Pesticide residues ingested depend, amongst other things, on individual spatial choices which determine how much and when feeding sites and areas of pesticide application overlap, and can be calculated using individual-based models (IBMs). Internal concentrations can be calculated using toxicokinetic (TK) models, which are quantitative representations of ADME processes. Here we provide a population model for the wood mouse (Apodemus sylvaticus) in which TK submodels were incorporated into an IBM representation of individuals making choices about where to feed. This allows us to estimate the contribution of individual spatial choice and TK processes to risk. We compared the risk predicted by four IBMs: (i) “AllExposed-NonTK”: assuming no spatial choice so all mice have 100% exposure, no TK, (ii) “AllExposed-TK”: identical to (i) except that the TK processes are included where individuals vary because they have different temporal patterns of ingestion in the IBM, (iii) “Spatial-NonTK”: individual spatial choice, no TK, and (iv) “Spatial-TK”: individual spatial choice and with TK. The TK parameters for hypothetical pesticides used in this study were selected such that a conventional risk assessment would fail. Exposures were standardised using risk quotients (RQ; exposure divided by LD50 or LC50). We found that for the exposed sub-population including either spatial choice or TK reduced the RQ by 37–85%, and for the total population the reduction was 37–94%. However spatial choice and TK together had little further effect in reducing RQ. The reasons for this are that when the proportion of time spent in treated crop (PT) approaches 1, TK processes dominate and spatial choice has very little effect, and conversely if PT is small spatial choice dominates and TK makes little contribution to exposure reduction. The latter situation means that a short time spent in the pesticide-treated field mimics exposure from a small gavage dose, but TK only makes a substantial difference when the dose was consumed over a longer period. We concluded that a combined TK-IBM is most likely to bring added value to the risk assessment process when the temporal pattern of feeding, time spent in exposed area and TK parameters are at an intermediate level; for instance wood mice in foliar spray scenarios spending more time in crop fields because of better plant cover.
Resumo:
Traces the development of new letterforms for printing in the first 30 years of the nineteenth century.
Resumo:
This article examines a little known decision of the Judicial Committee of the Privy Council: Grand Trunk Railway Company of Canada v Robinson (1915). The examination is historical and it provides a different insight into the understanding of privity of contract, a doctrine central to contract law. The examination reveals a process of trans-Atlantic legal migration in which English law was applied to resolve an Ontario case. The nature of the resolution is surprising because it appears to conflict with the better known decision of the House of Lords, Dunlop Pneumatic Tyre Company, Limited v Selfridge and Company, Limited, which a similarly constituted panel delivered in the same week. This article argues that there was a greater malleability in the resolution of cases concerned with privity than was thought to have existed. It is also argued that the power of Canadian railway capitalism is a significant factor in understanding the legal resolution of the case. Finally, it the article considers the use of English and American precedents relevant to the case. The application of English precedents to the case led to a resolution not entirely befitting Canadian conditions.
