104 resultados para STRETCHING LIMITS
Resumo:
The valuation of environmental benefits has been well researched in the forestry sector. This is not generally the case in the agriculture sector although schemes to compensate farmers for provision of officially defined environmental benefits are already in place throughout the European Union. This paper draws on empirical findings from forestry and deductions from economic theory to challenge the notion of the universality of such benefits. Empirical findings from forestry suggest recreational use value is location specific rather than widely spread. Household utility theory predicts zero willingness to pay to maintain the status quo level of a previously unpaid for environmental benefit (when provision is not perceived as under risk) but a positive willingness to pay for an increase. Thus, non use values cannot be attributed to the major part of existing commercial forestry area but to spatially restricted schemes such as additional afforestation or preservation of ancient natural woodlands.
Resumo:
A reconnaissance of 23 paddy fields, from three Bangladesh districts, encompassing a total of 230 soil and rice plant samples was conducted to identify the extent to which trace element characteristics in soils and irrigation waters are reflected by the harvested rice crop. Field sites were located on two soil physiographic units with distinctly different As soil baseline and groundwater concentrations. For arsenic (As), both straw and grain trends closely fitted patterns observed for the soils and water. Grain concentration characteristics for selenium (Se), zinc (Zn), and nickel (Ni), however, were markedly different. Regressions of shoot and grain As against grain Se, Zn, and Ni were highly significant (P <0.001), exhibiting a pronounced decline in grain trace-nutrient quality with increasing As content. To validate this further, a pot experiment cultivar screening trial, involving commonly cultivated high yielding variety (HYV) rice grown alongside two U.S. rice varieties characterized as being As tolerant and susceptible, was conducted on an As-amended uniform soil. Findings from the trial confirmed that As perturbed grain metal(loid) balances, resulting in severe yield reductions in addition to constraining the levels of Se, Zn, and Ni in the grain.
Resumo:
This paper focuses on the revival of private property and its limits in urban China. It explores the emergence of urban property markets; urban property-holding in relation to the complexity of urban governance; “minor property rights apartments” that form a de facto real estate market and cross over the urban-rural divide; the “grey areas” of blurring legal and administrative boundaries in modern China; and recent changes to the rural land system and the rural-urban divide. The conclusion flags the theme of the city as laboratory with regard to the blurring legal and governmental urban-rural distinction.
Resumo:
Polypropylene sheets have been stretched at 160 °C to a state of large biaxial strain of extension ratio 3, and the stresses then allowed to relax at constant strain. The state of strain is reached via a path consisting of two sequential planar extensions, the second perpendicular to the first, under plane stress conditions with zero stress acting normal to the sheet. This strain path is highly relevant to solid phase deformation processes such as stretch blow moulding and thermoforming, and also reveals fundamental aspects of the flow rule required in the constitutive behaviour of the material. The rate of decay of stress is rapid, and such as to be highly significant in the modelling of processes that include stages of constant strain. A constitutive equation is developed that includes Eyring processes to model both the stress relaxation and strain rate dependence of the stress. The axial and transverse stresses observed during loading show that the use of a conventional Levy-Mises flow rule is ineffective, and instead a flow rule is used that takes account of the anisotropic state of the material via a power law function of the principal extension ratios. Finally the constitutive model is demonstrated to give quantitatively useful representation of the stresses both in loading and in stress relaxation.
Resumo:
Signal initiation by engagement of the TCR triggers actin rearrangements, receptor clustering, and dynamic organization of signaling complexes to elicit and sustain downstream signaling. Nef, a pathogenicity factor of HIV, disrupts early TCR signaling in target T cells. To define the mechanism underlying this Nef-mediated signal disruption, we employed quantitative single-cell microscopy following surface-mediated TCR stimulation that allows for dynamic visualization of distinct signaling complexes as microclusters (MCs). Despite marked inhibition of actin remodeling and cell spreading, the induction of MCs containing TCR-CD3 or ZAP70 was not affected significantly by Nef. However, Nef potently inhibited the subsequent formation of MCs positive for the signaling adaptor Src homology-2 domain-containing leukocyte protein of 76 kDa (SLP-76) to reduce MC density in Nef-expressing and HIV-1-infected T cells. Further analyses suggested that Nef prevents formation of SLP-76 MCs at the level of the upstream adaptor protein, linker of activated T cells (LAT), that couples ZAP70 to SLP-76. Nef did not disrupt pre-existing MCs positive for LAT. However, the presence of the viral protein prevented de novo recruitment of active LAT into MCs due to retargeting of LAT to an intracellular compartment. These modulations in MC formation and composition depended on Nef's ability to simultaneously disrupt both actin remodeling and subcellular localization of TCR-proximal machinery. Nef thus employs a dual mechanism to disturb early TCR signaling by limiting the communication between LAT and SLP-76 and preventing the dynamic formation of SLP-76-signaling MCs.
Resumo:
We investigate the so-called nonresonant cosmic-ray streaming instability, first discussed by Bell (2004). The extent to which thermal damping and ion-neutral collisions reduce the growth of this instability is calculated. Limits on the growth of the nonresonant mode in SN1006 and RX J1713.7-3946 are presented.
Resumo:
Political parties have only recently become a subject of investigation in political theory. In this paper I analyse religious political parties in the context of John Rawls’s political liberalism. Rawlsian political liberalism, I argue, overly constrains the scope of democratic political contestation and especially for the kind of contestation channelled by parties. This restriction imposed upon political contestation risks undermining democracy and the development of the kind of democratic ethos that political liberalism cherishes. In this paper I therefore aim to provide a broader and more inclusive understanding of ‘reasonable’ political contestation, able to accommodate those parties (including religious ones) that political liberalism, as customarily understood, would exclude from the democratic realm. More specifically, I first embrace Muirhead and Rosenblum’s (Perspectives on Politics 4: 99–108 2006) idea that parties are ‘bilingual’ links between state and civil society and I draw its normative implications for party politics. Subsequently, I assess whether Rawls’s political liberalism is sufficiently inclusive to allow the presence of parties conveying religious and other comprehensive values. Due to Rawls’s thick conceptions of reasonableness and public reason, I argue, political liberalism risks seriously limiting the number and kinds of comprehensive values which may be channelled by political parties into the public political realm, and this may render it particularly inhospitable to religious political parties. Nevertheless, I claim, Rawls’s theory does offer some scope for reinterpreting the concepts of reasonableness and public reason in a thinner and less restrictive sense and this may render it more inclusive towards religious partisanship.
Resumo:
A survey of the use of the term democracy in Irish politics in the late eighteenth and early ninetenth centuries