Pointwise Asymptotic Behavior of Perturbed Viscous Shock Profiles

We consider the asymptotic behavior of perturbations of Lax and overcompressive type viscous shock profiles arising in systems of regularized conservation laws with strictly parabolic viscosity, and also in systems of conservation laws with partially parabolic regularizations such as arise in the case of the compressible Navier--Stokes equations and in the equations of magnetohydrodynamics. Under the necessary conditions of spectral and hyperbolic stability, together with transversality of the connecting profile, we establish detailed pointwise estimates on perturbations from a sum of the viscous shock profile under consideration and a family of diffusion waves which propagate perturbation signals along outgoing characteristics. Our approach combines the recent $L^p$-space analysis of Raoofi [$L^p$ Asympototic Behavior of Perturbed Viscous Shock Profiles, to appear J. Hyperbolic Differential Equations] with a straightforward bootstrapping argument that relies on a refined description of nonlinear signal interactions, which we develop through convolution estimates involving Green's functions for the linear evolutionary PDE that arises upon linearization of the regularized conservation law about the distinguished profile. Our estimates are similar to, though slightly weaker than, those developed by Liu in his landmark result on the case of weak Lax type profiles arising in the case of identity viscosity [Pointwise Convergence to Shock Waves for Viscous Conservation Laws, Comm. Pure Appl. Math. 50 (1997) 1113--1182]

Optimal Preservation of Agricultural and Environmental Land within a Municipality Under Irreversibility and Uncertainty

Replaced with revised version of paper 07/22/11.Uncertainty, Irreversibility, Spatial-temporal modeling, Value of information, Policy design, Climate change, Agricultural preservation, Environmental conservation, Environmental Economics and Policy, Land Economics/Use, Political Economy, Risk and Uncertainty,

Survey of Foreign Aid: History, Trends and Allocation

This paper (i) traces the historical origins of foreign aid, (ii) investigates tren­ds in the volume, composition, allocation and quality of aid flows, and (iii) reviews the empirical literature on aid allocation. The paper concludes that, historically, aid has served a multitude of objectives. For some donors, the allocation and quality of aid have been largely shaped by concern for the development needs of recipients. By contrast, the foreign aid of some larger donors has been used principally as a foreign and commercial policy tool. Yet while this particular character of aid flows may well have impaired the effectiveness of aid, there is no automatic contradiction between donor and recipient objectives. Perhaps the most important change in the aid picture is the reversal after 1992 of the historic upward trend in aid volumes. This may not be a problem when smaller aid flows are compensated by private flows, as has happened in several developing countries. Yet it may be a problem in low-income countries without access to private capital, which continue to rely on aid for financial resources. The underlying premises of donor-recipient cooperation are very different when aid resources become more limited, especially when debt service is still a factor of significance. The need to keep objectives and rationales clear turn out to be even more important.Foreign Aid; Aid Allocation

Sharp pointwise bounds for perturbed viscous shock waves

Refining previous work in \cite{Z.3, MaZ.3, Ra, HZ, HR}, we derive sharp pointwise bounds on behavior of perturbed viscous shock profiles for large-amplitude Lax or overcompressive type shocks and physical viscosity. These extend well-known results of Liu \cite{Liu97} obtained by somewhat different techniques for small-amplitude Lax type shocks and artificial viscosity, completing a program set out in \cite{ZH}. As pointed out in \cite{Liu91, Liu97}, the key to obtaining sharp bounds is to take account of cancellation associated with the property that the solution decays faster along characteristic than in other directions. Thus, we must here estimate characteristic derivatives for the entire nonlinear perturbation, rather than judicially chosen parts as in \cite{Ra, HR}. a requirement that greatly complicates the analysis.Comment: 59 p

Pre-letting of office developments : a guide for occupiers

‘Pre-letting’ is an agreement between a potential tenant and a developer to lease a building whose construction has not yet started. Benefits typically flow to both parties from a pre-letting, however, opportunities to pre-let are limited by place, time, market forces and the negotiation strength of both parties. This research bulletin, which has been produced jointly with Northumbria University, involved interviewing 30 office occupiers and developers who have been involved in prelet agreements throughout the UK. It examines the pros and cons of taking a pre-let, the typical lease terms, and design issues. It also looks at where and when pre-lettings are most likely to occur

Appropriate Economic Space for Transnational Infrastructural Projects: Gateways, Multimodal Corridors, and Special Economic Zones

This study addresses three questions that arise in Asia when formulating, financing, implementing, and maintaining transnational linkages versus purely domestic connections. Firstly, how is optimal economic space to be defined as a useful starting point? Secondly, how can relevant criteria be developed to define the emerging spatial economy and identify efficient transnational transport networks? Thirdly, what are the main investment opportunities in physical infrastructure that would result in more efficient and effective regional cooperation and integration (making special reference to the potential role of cross-border special economic zones (SEZs) or their equivalents)?asia transnational infrastructure; asia regional cooperation