Sasakian quiver gauge theory on the Aloff-Wallach space X1,1X_{1,1}

We consider the SU(3)-equivariant dimensional reduction of gauge theories on spaces of the form $M^d \times X_{1,1}$ with d-dimensional Riemannian manifold $M^d$ and the Aloff-Wallach space $X_{1,1}$= SU(3)/U(1) endowed with its Sasaki-Einstein structure. The condition of SU(3)-equivariance of vector bundles, which has already occurred in the studies of Spin(7)-instantons on cones over Aloff-Wallach spaces, is interpreted in terms of quiver diagrams, and we construct the corresponding quiver bundles, using (parts of) the weight diagram of SU(3). We consider three examples thereof explicitly and then compare the results with the quiver gauge theory on $Q_3$ =SU(3)/(U(1) x U(1)), the leaf space underlying the Sasaki-Einstein manifold $X_{1,1}$. Moreover, we study instanton solutions on the metric cone $C(X_{1,1})$ by evaluating the Hermitian Yang-Mills equation. We briefly discuss some features of the moduli space thereof, following the main ideas of a treatment of Hermitian Yang-Mills instantons on cones over generic Sasaki-Einstein manifolds in the literature.Comment: 25 page

Experimental research on turbulent reacting flows using gaseous and liquid fuels

An investigation into turbulent reacting flows in an opposed jet geometry and a sudden expansion duct has been performed. For the opposed jet geometry, measurements of the velocity and reaction progress variable were obtained in lean premixed flames. Both velocity and scalar measurements were taken using PIV (Particle Image Velocimetry). Three gaseous fuels (methane, propane and ethylene) and three liquid fuels (JP-10, cyclopentane and cyclopentene) were considered for a range of equivalence ratios. The broad range of fuels enabled an investigation of the effect of different fuel reactivities on the velocity field and flame location and also allowed the effect of the Lewis number on flame extinction to be investigated. Preliminary work included isothermal measurements of the flow between and inside the nozzles. The use of fractal grids inside the nozzle increased turbulence intensities at the nozzle exit by 100% and turbulent Reynolds numbers between 50 - 220 were achieved. Velocity and normal stress components were measured with attention focused on the inlet boundary, along the burner centreline and the stagnation plane. A circular duct, incorporating a sudden expansion step, was also used to investigate the effect of swirl on pressure oscillations within the duct, the lean flammability limits and the NOx emissions. Measurements were performed for stratified flow conditions using methane as a fuel. The results show that excessive swirl leads to an increase in local strain in the vicinity of the expansion step and makes the flame more prone to local extinction. Moderate swirl was found to lower the amplitudes of the pressure oscillations close to global extinction and also to decrease the lean extinction limit of the stratified flow conditions. However, it did not decrease the overall equivalence ratio of flows with a richer core and a leaner annulus. Flows with only air in the core flow led to an overall equivalence ratio as lean as 0.3 for methane compared with 0.6 for the uniform flow. Stratification with a fuel rich core flow and a leaner annular flow led to an increase in NOx emissions due to locally increased temperatures. The addition of moderate swirl enhanced mixing of the annular and the core flows, which resulted in a more uniform fuel distribution close to the step and a reduction in NOx-levels up to 50%

Working to increase backwards linkages from mining investment

During my MSc Development Studies degree at LSE, one of the topics that interested me most was Albert Hirschman’s concept of backwards linkages. Briefly, he defined backward linkage effects as when the establishment of a new industry creates possibilities for local industries to expand production through the supply of inputs to the new entrant to the economy. He argued that developing countries could benefit from creating backwards linkages whereby domestic enterprises would supply the operations of investing companies

The chance to get it right: Africa’s opportunity to truly benefit from mining investment

Former Development Studies student, Jeff Geipel, now Venture Lead for Mining Shared Value, Engineers Without Borders Canada, talks about the importance of the Mining on Top: Africa Summit taking place in London this week from June 24-26. [See original PDF here.

Pathogenic organisms in hip joint infections

Infections of the hip joint are usually of bacterial etiology. Only rarely, an infectious arthritis is caused in this localization by viruses or fungi. Native joint infections of the hip are less common than infections after implantation of prosthetic devices. Difficulties in prosthetic joint infections are, (I) a higher age of patients, and, thus an associated presence of other medical risk factors, (II) often long courses of treatment regimes depending on the bacterium and its antibiotic resistance, (III) an increased mortality, and (IV) a high economic burden for removal and reimplantation of an infected prosthetic device. The pathogenic mechanisms responsible for articular infections are well studied only for some bacteria, e.g. Staphylococcus aureus, while others are only partially understood. Important known bacterial properties and microbiological characteristics of infection are the bacterial adhesion on the native joint or prosthetic material, the bacterial biofilm formation, the development of small colony variants (SCV) as sessile bacterial types and the increasing resistance to antibiotics

Omnidirectional acceleration device Patent

Omnidirectional liquid filled accelerometer design with liquid and housing temperature compensatio

Sasakian quiver gauge theories and instantons on cones over round and squashed seven-spheres

We study quiver gauge theories on the round and squashed seven-spheres, and orbifolds thereof. They arise by imposing $G$-equivariance on the homogeneous space $G/H=\mathrm{SU}(4)/\mathrm{SU}(3)$ endowed with its Sasaki-Einstein structure, and $G/H=\mathrm{Sp}(2)/\mathrm{Sp}(1)$ as a 3-Sasakian manifold. In both cases we describe the equivariance conditions and the resulting quivers. We further study the moduli spaces of instantons on the metric cones over these spaces by using the known description for Hermitian Yang-Mills instantons on Calabi-Yau cones. It is shown that the moduli space of instantons on the hyper-Kahler cone can be described as the intersection of three Hermitian Yang-Mills moduli spaces. We also study moduli spaces of translationally invariant instantons on the metric cone $\mathbb{R}^8/\mathbb{Z}_k$ over $S^7/\mathbb{Z}_k$.Comment: 44 pages; v2: minor changes, reference added; Final version to appear in Nuclear Physics

Ökologischer Anbau von Äpfeln ohne den Einsatz von Pflanzenschutzmitteln

Plant protection is still a burning issue in organic apple production. Insufficient strategies lead to minor quali-ties and immense profit cuts. To thwart these problems and to support organic apple production a program has been started to test a new cultivation system for apple farming. Preconditions for the profitability of the new method are a high yield of premium quality apples comparable to those reached in conventional farming. Main components of the new cultivation system are a foil canopy to prevent fungal infections and lateral net-tings for protection against animal pests and to allow the application of beneficial organisms. To meet the top claims of organic production no chemical plant protection is performed and EU regulations are regarded. The program funded by the Bavarian State Ministry of Agriculture and Forestry started in 2002. First results show the practicability of the new cultivation system for organic apple production but also deficiencies still to be solved