Quantum effects in linear and non-linear transport of T-shaped ballistic junction

We report low-temperature transport measurements of three-terminal T-shaped device patterned from GaAs/AlGaAs heterostructure. We demonstrate the mode branching and bend resistance effects predicted by numerical modeling for linear conductance data. We show also that the backscattering at the junction area depends on the wave function parity. We find evidence that in a non-linear transport regime the voltage of floating electrode always increases as a function of push-pull polarization. Such anomalous effect occurs for the symmetric device, provided the applied voltage is less than the Fermi energy in equilibrium

Ethical trading and socioeconomic transformation: critical reflections on the South African wine industry

Newly emerging ethical trade practices in the South African wine industry are examined as a way of engaging with debates about the ability of alternative trade approaches to facilitate meaningful opportunities for socioeconomic development in the global South. The South African wine industry has undergone rapid restructuring since the end of apartheid in order to meet the demands of international markets. However, transforming racially skewed ownership and skill patterns is proving a particular challenge. In this paper we outline some of the initiatives that have been introduced to stimulate socioeconomic change within the industry. By utilising analytical tools such as commodity chains, networks, and cultural approaches we demonstrate that a complex array of forces is driving change on the ground. Such forces include national imperatives derived from the legacy of apartheid and the concerns of consumers in the global North. We conclude by considering the types of local and global constraints that need to be challenged if these initiatives are to be successful in facilitating meaningful socioeconomic transformation within the wine industry

Fairtrade, place and moral economy: between abstract ethical discourse and the moral experience of Northern Cape farmers

This paper explores the significance of the relationships and disjunctures between the global moral discourses of Fairtrade that are articulated through ethics of fairness in supply chains and the everyday moral experiences, discourses and practices of producers that shape moral economies in specific localities. Due to increased governance through universal codes, standards and certification, Fairtrade risks becoming an abstract ethical and regulatory tool, disconnected from the moral economies of those poor farmers it is intended to benefit. In response, the paper makes a case for a deeper understanding of the moral economies of farmers involved in Fairtrade networks and the ways in which these emerge out of moral experiences that are deeply embedded in local social and cultural relations. Through a case study of Eksteenskuil Agricultural Cooperative in South Africa’s Northern Cape, it seeks to demonstrate the importance of understanding the moral experiences of producers to better consider what is at stake for them, focusing on notions of cooperation, fairness and the ‘good farmer’, perceptions of community, and concerns with survival and self-sufficiency. The paper concludes that working in culturally-sensitive ways with producer communities and understanding how their local moral worlds are structured is vital in bridging the gap between abstract ethical discourses and the place-based moral experiences of producers, and to ensuring the effectiveness of Fairtrade initiatives

TE INTEGRATION OF WATER HYDRODYNAMICS MODELLING AND REMOTE SENSING DATA TO IMPROVE THE WATER CIRCULATION OF LAKE MANZALA, EGYPT

This paper presents the preliminary results of the application of the ocean model (FVCOM) to replicate the hydrodynamic flows experienced within Lake El-Manzala, Egypt. The construction of this model is used to characterize the ecosystem of this shallow brackish lake and assess a range of sustainable water management strategies. Lake El-Manzala is the largest of the Egyptian shallow coastal lakes on the fringe of the Mediterranean Sea. The lake currently supports 30% of the fresh water fish farm production of Egypt. In recent years the aquatic health of the lake has significantly deteriorated due to an increase in the contamination of the lake by polluted inflows and over intensive aquaculture. The focus of this study is to develop a model that may be employed to investigate the causes, effects and potential solutions to the pollutant loads imposed on the lake. The model has been used to study the hydrodynamic effect that a 40% reduction in the polluted drain water inflows to the lake due to a diversion of this water towards the Sinai for land development. This study concluded that in the western zone of the lake this action slightly changed the magnitude and direction of the water flows and an increase in the salinity levels. Several other lake management scenarios were proposed and the environmental effects on the lake water quality are under investigation. It is concluded that the hydrodynamic models developed may be used to study the cause and effects of other aquatic pollution problems and permit the investigation of potential engineering solutions to improve water quality management

Engineering nonlinear response of nanomaterials using Fano resonances

We show that nonlinear optical processes of nanoparticles can be controlled by the presence of interactions with a molecule or a quantum dot. By choosing the appropriate level spacing for the quantum emitter, one can either suppress or enhance the nonlinear frequency conversion. We reveal the underlying mechanism for this effect, which is already observed in recent experiments: (i) suppression occurs simply because transparency induced by Fano resonance does not allow an excitation at the converted frequency, and (ii) enhancement emerges since the nonlinear process can be brought to resonance. The path interference effect cancels the nonresonant frequency terms. We demonstrate the underlying physics using a simplified model, and we show that the predictions of the model are in good agreement with the three-dimensional boundary element method (MNPBEM toolbox) simulations. Here, we consider the second harmonic generation in a plasmonic converter as an example to demonstrate the control mechanism. The phenomenon is the semi-classical analog of nonlinearity enhancement via electromagnetically induced transparency. © 2014 IOP Publishing Ltd

The application of a validated hydrodynamic model to improve the water management of an Egyptian shallow water coastal lake

This paper presents the preliminary results of the application of the ocean model (FVCOM)to replicate the hydrodynamic flows experienced within Lake El-Manzala, Egypt. Theconstruction of this model is used to characterize the ecosystem of this shallow brackishlake and assess a range of sustainable water management strategies. Lake El-Manzala is thelargest of the Egyptian shallow coastal lakes on the fringe of the Mediterranean Sea. Thelake currently supports 30% of the fresh water fish farm production of Egypt. In recentyears the aquatic health of the lake has significantly deteriorated due to an increase in thecontamination of the lake by polluted inflows and over intensive aquaculture. The focus ofthis study is to develop a model that may be employed to investigate the causes, effects andpotential solutions to the pollutant loads imposed on the lake. The model has been used tostudy the hydrodynamic effect that a 40% reduction in the polluted drain water inflows tothe lake due to a diversion of this water towards the Sinai for land development. This studyconcluded that this action resulted in an improvement in the water circulation of the northwesternsector of the lake. The salinity increased in the southern part of the lake. Severalother lake management scenarios were proposed and the environmental effects on the lakewater quality are under investigation. It is concluded that the hydrodynamic modelsdeveloped may be used to study the cause and effects of other aquatic pollution problemsand permit the investigation of potential engineering solutions to improve water qualitymanagement