Ageing in Mortal Superdiffusive L\'evy Walkers

A growing body of literature examines the effects of superdiffusive subballistic movement pre-measurement (ageing or time lag) on observations arising from single-particle tracking. A neglected aspect is the finite lifetime of these L\'{e}vy walkers, be they proteins, cells or larger structures. We examine the effects of ageing on the motility of mortal walkers, and discuss the means by which permanent stopping of walkers may be categorised as arising from `natural' death or experimental artefacts such as low photostability or radiation damage. This is done by comparison of the walkers' mean squared displacement (MSD) with the front velocity of propagation of a group of walkers, which is found to be invariant under time lags. For any running time distribution of a mortal random walker, the MSD is tempered by the stopping rate $\theta$. This provides a physical interpretation for truncated heavy-tailed diffusion processes and serves as a tool by which to better classify the underlying running time distributions of random walkers. Tempering of aged MSDs raises the issue of misinterpreting superdiffusive motion which appears Brownian or subdiffusive over certain time scales

An investigation of the marine boundary layer during cold air outbreak

Methods for use in the remote estimation of ocean surface sensible and latent heat fluxes were developed and evaluated. Three different techniques were developed for determining these fluxes. These methods are: (1) Obtaining surface sensible and latent heat fluxes from satellite measurements; (2)Obtaining surface sensible and latent heat fluxes from an MABL model; (3) A method using horizontal transfer coefficients. These techniques are not very sensitive to errors in the data and therefore appear to hold promise of producing useful answers. Questions remain about how closely the structure of the real atmosphere agrees with the assumptions made for each of these techniques, and, therefore about how well these techniques can perform in actual use. The value of these techniques is that they promise to provide methods for the determination of fluxes over regions where very few traditional measurement exist

Optimal Tax and Expenditure Policy in the Presence of Migration - Are Credit Restrictions Important?

This paper concerns optimal income taxation in the presence of emigration. The basic model is a two-period model where all agents are identical and live in the home country in the first period of life, but where some emigrate at the end of the first period. It is shown that with a binding credit restriction, the government will tax labor income in the first period at a higher rate than otherwise, whereas the labor income tax in the second period is unaffected by emigration. With heterogenous agents, the labor income tax in period two will be affected by emigration.optimal taxation; labor mobility; intertemporal consumer choice

The economic impact of climate change in Namibia. How climate change will affect the contribution of Namibia’s natural resources to its economy

The IPCC recognises Africa as a whole to be “one of the most vulnerable continents to climate variability and change because of multiple stresses and low adaptive capacity. Climate change is likely to exacerbate the dry conditions already experienced in southern Africa. And when rainfall does come, it is likely to be more intense, leading to erosion and flood damage. This will affect the poor most, with resulting constraints on employment opportunities and declining wages. But at present these predictions gain little policy traction in southern African countries. The multilateral climate change process is complicated and slow, and policymakers often see serious action on climate change as a domestic ‘vote loser’. One way to raise climate change concerns further up the policymakers’ agenda is to try to put an economic value on the environmental impacts of climate change. Figures that provide a clear message about the expected impact of climate change will be powerful motivators for policymakers in developing countries to start considering climate change as a part of their national development policies. This study is a first attempt to provide some economic indicators of how climate change will affect Namibia – one of the most vulnerable countries in sub-Saharan Africa. Focusing on natural resources, the study aims to assess the likely economic values of some of the most important environmental and socio-economic impacts of climate change in Namibia, and also to capture how some of the most important impacts might affect the overall structure of the economy.Climate change, Economics, Namibia, Environmental Economics and Policy,

Giving credit to the microlenders. Formal microlending, credit constraints and adverse selection: a case study of shrimp farmers in Bangladesh

Smallholder farmers have long been denied access to formal credit, largely because of the high administrative fees associated with loans. A possible solution to this problem, which has become increasingly popular, is the use of microcredit financing, where innovative means of securing the loans, such as peer monitoring, are used. This paper examines the effectiveness of formal microcredit schemes as compared to the traditional informal credit sources in a rural shrimp farming district of Bangladesh. We compare the two types of credit by studying the technical and allocative efficiencies of the two groups of borrowers. The findings suggest that farmers using both types of microcredit have difficulty accessing credit, often over-utilising labour in order to reduce the need for inputs that require cash at the beginning of the season, creating inefficiencies in production. However, the informal lenders, with their closer ties to individual farmers, were more successful in identifying those small-holders most likely to make the best use of the borrowed funds. Thus, although formal microcredit schemes do not impose the high administrative fees of traditional formal lending, they do not necessarily solve the problem of how to select successful borrowers.Economics, Bangladesh, Shrimp Farming, Fisheries, Community/Rural/Urban Development, Crop Production/Industries, Environmental Economics and Policy, Financial Economics, Livestock Production/Industries,

Turbulent statistics in the vicinity of an SST front: A north wind case, FASINEX February 16, 1986

The technique of boxcar variances and covariances is used to examine NCAR Electra data from FASINEX (Frontal Air-Sea Interaction EXperiment). This technique was developed to examine changes in turbulent fluxes near a sea surface temperature (SST) front. The results demonstrate the influence of the SST front on the MABL (Marine Atmospheric Boundary Layer). Data shown are for February 16, 1986, when the winds blew from over cold water to warm. The front directly produced horizontal variability in the turbulence. The front also induced a secondary circulation which further modified the turbulence