Structure And Dynamics Of Modulated Traveling Waves In Cellular Flames

We describe spatial and temporal patterns in cylindrical premixed flames in the cellular regime, $Le < 1$, where the Lewis number $Le$ is the ratio of thermal to mass diffusivity of a deficient component of the combustible mixture. A transition from stationary, axisymmetric flames to stationary cellular flames is predicted analytically if $Le$ is decreased below a critical value. We present the results of numerical computations to show that as $Le$ is further decreased traveling waves (TWs) along the flame front arise via an infinite-period bifurcation which breaks the reflection symmetry of the cellular array. Upon further decreasing $Le$ different kinds of periodically modulated traveling waves (MTWs) as well as a branch of quasiperiodically modulated traveling waves (QPMTWs) arise. These transitions are accompanied by the development of different spatial and temporal symmetries including period doublings and period halvings. We also observe the apparently chaotic temporal behavior of a disordered cellular pattern involving creation and annihilation of cells. We analytically describe the stability of the TW solution near its onset+ using suitable phase-amplitude equations. Within this framework one of the MTW's can be identified as a localized wave traveling through an underlying stationary, spatially periodic structure. We study the Eckhaus instability of the TW and find that in general they are unstable at onset in infinite systems. They can, however, become stable for larger amplitudes.Comment: to appear in Physica D 28 pages (LaTeX), 11 figures (2MB postscript file

Research communication

In this paper we review briefly histories and ideologies underlying multiculturalism in Nordic countries, highlighting tensions between integrationist and inclusive approaches. We propose a cultural ecological framework through which we discuss the possibility of a transculturalism based on Fourth World engagement with the environment. Cultural ecology is about the reciprocal interactions and transactions between people and their environments. The Fourth World is a circum-global, pan-arctic region which includes the northern parts of some Nordic countries. We argue that whether or not there is a distinctively Nordic version of multiculturalism, Nordic countries have access to Fourth World ways of engaging with the environment which transcend notions of inter- and multiculturalism and the ideological tensions associated with them

Private Sector Participation in African Infrastructure: Is it Worth the Risk?

Policies to promote privatisation in developing-country infrastructure gained momentum in the early 1990s as donors grew increasingly frustrated with efforts to strengthen public sector services that continued to fail. The strategy was intended to bring both finance and efficiency to ailing infrastructure throughout the developing world. Nearly two decades later the results have been disappointing, particularly in the areas of greatest need. The extent of investor interest in water and electricity in Sub-Saharan Africa (SSA) was massively overestimated and the hoped-for private investment failed to materialise. Rates of access to electricity and water remain far below those of other developing regions. In response to the failings of privatisation there has been a redoubling of efforts to attract investors, albeit with the recognition that this might take longer than originally thought. Privatisation in various guises is still prominent on the policy agenda. This paper critically assesses the motives behind the drive for private sector participation (PSP) in water and electricity in SSA, and reviews measures adopted by governments and donors to entice investors. In terms of restructuring and pricing, sector policies have the underlying objective of facilitating private investment and reducing the risk exposure for potential investors. In addition, a plethora of donor initiatives have emerged with the aim of bringing private investment into the region, and these too focus on reducing risk for the private sector. As a result, on offer to the private sector are the least challenging and most lucrative aspects of delivery, which are tightly ring-fenced and bound by guarantees. In industrialised economies, discussions of the merits of PSP highlight the importance of transferring risk to the private sector in order to generate efficiency gains. In contrast, as regards attracting PSP into utilities in SSA, the focus is on reducing the risk to which the private sector is exposed. But this risk is not reduced, it is transferred. As a result, African governments, taxpayers and end-users bear high levels of risk in order to accommodate the priorities of investors. (...)Private Sector Participation in African Infrastructure: Is it Worth the Risk?

Lessons from the South African Electricity Crisis

South Africa is suffering an electricity crisis. Blackouts have been widespread and the impact disastrous. Electricity supply is predicted to constrain growth for at least the next five years. How could this have occurred when until recently South Africa had a surplus of cheap electricity? This One Pager explores the causes. (...)Lessons from the South African Electricity Crisis

Financing Water in Africa

Despite repeated policy initiatives from donors and governments, the human and economic cost of continued lack of access to safe water and sanitation in sub-Saharan Africa remains high. Progress is in large part constrained by a persistent ‘financing gap’. This paper shows that a radical reorientation of policy is needed to achieve a significant increase in investment finance in order to raise access levels. Rather than continuing to pursue policies that have failed for the past two decades, such as attempting to attract the private sector and raising prices to cost recovery levels, attention needs to shift to wider aspects of domestic revenue mobilization to support public investment

Towards data grids for microarray expression profiles

The UK DTI funded Biomedical Research Informatics Delivered by Grid Enabled Services (BRIDGES) project developed a Grid infrastructure through which research into the genetic causes of hypertension could be supported by scientists within the large Wellcome Trust funded Cardiovascular Functional Genomics project. The BRIDGES project had a focus on developing a compute Grid and a data Grid infrastructure with security at its heart. Building on the work within BRIDGES, the BBSRC funded Grid enabled Microarray Expression Profile Search (GEMEPS) project plans to provide an enhanced data Grid infrastructure to support richer queries needed for the discovery and analysis of microarray data sets, also based upon a fine-grained security infrastructure. This paper outlines the experiences gained within BRIDGES and outlines the status of the GEMEPS project, the open challenges that remain and plans for the future

Attitudes and decision making amongst Scottish organic farmers

The number of organic farmers in Scotland increased dramatically in the period between 1997 and 2000, from 120 in 1997 to approximately 600 at the end of 2000; a five fold increase. Currently the outlook for organic farming in Scotland appears positive, despite recent publicity about farmers leaving the sector. Market prospects for all organic commodities are buoyant and there are increased Scottish Executive Organic Aid Scheme (OAS) maintenance payments in the offing. But what do Scotland’s organic producers really think about the system, which has them, tied in for at least five years? In June 2004, a representative group of Scottish organic farmers in the South of Scotland was surveyed to determine how many intended to continue farming organically once they had completed the OAS and to consider the factors affecting their decisions regarding organic conversion and cessation. Results indicated that 55% of respondents intended to continue farming organically in the short term whilst 37% intended to continue for the long term (the next decade). Although half of the respondents indicated that they were greatly influenced to convert to organic farming for wider environmental benefits and 45% for perceived job satisfaction, by far the biggest influence cited was financial benefit. Sixty nine per cent of respondents cited OAS subsidies and 55% cited the perceived price premium on produce. These fi ndings were confirmed in a second survey of organic farmers in Central Scotland between November 2004 and January 2005. In this second survey almost half (49%) of respondents cited increased long term financial returns and 44% cited the short-term cash injection from OAS payments as being of great importance in the decision to convert. The Central Scotland survey also indicated that stress and pressure on farmers following conversion was remarkably high, perhaps as a result of farmers having to adopt new practices and procedures; 97% of respondents reported increased paperwork and 79% stated that they required increased management skills. However, anecdotal evidence suggests that farmers’ attitude to organic farming changes over time from initial apprehension to more confidence in production methods and the system in general. Factors impeding farmers’ efforts to farm organically were primarily issues relating to cash flow, certification bodies, standards and marketing. Marketing issues were perceived or found to be the main problem after full organic status was achieved in the SW Scotland survey. The Central Scotland survey indicates insufficient price premiums and lack of local outlets as the main factors for cessation of organic farming. Both surveys also concur on the fact that hill farmers are more likely to leave organic farming in the short term than their upland and lowland counterparts. However, respondents from both surveys who did not intend to continue farming organically stated they planned to continue farming extensively using organic farming methods and systems