Addressing Accra's urban water challenges within a sustainable development context

Like most major cities in Africa, Accra is undergoing a rapid pace of urbanization fueled by economic development, population growth and rural to urban migration. The city faces major challenges with the provision of adequate and effective urban water infrastructure. The challenges associated with perennial flooding in Accra are reviewed in the context of recommended policy, institutional and organizational changes that are deemed to provide a more sustainable and holistic approach to urban water service provision. These have the potential of increasing the interactions of multiple stakeholders including the public, system designers, urban planners, entrepreneurs, activists, etc. and fostering an even closer link between professional practice and community participation providing the scope for spurning innovation, capacity building and job creation at a local level

Effects Of Cutting Parameters On Acoustic Emission Signal Response During Drilling Of Laminated Composites Using Factorial Design Method

Factorial design has been used to study the effect of cutting parameters on acoustic emission signal response during the drilling of composite laminates. Experimental design is a strategy of planning, conducting, analyzing and interpreting experiments so that sound and valid conclusion can be drawn efficiently, and economically. In this study, effects of cutting speed, feed rate and tool diameter on the acoustic emission signal response are investigated using acoustic emission\'s energy, amplitude, root mean square and frequency responses and 23 factorial design for drilling operation. Cutting tests were performed under dry conditions. Calculated effects, standard errors at 95% confidence level, and models governing the acoustic emission response to the cutting conditions have been generated from the acoustic emission signal responses. The results revealed that, acoustic energy response has significant effects due to the cutting parameters. Hence a model can be established to relate the acoustic emission\'s energy response and the cutting parameters, and as a result monitor and control the area of delamination during the drilling process.Journal of Science & Technology (Ghana) Vol. 27 (2) 2007: pp. 98-10

Quasi-Automatic Monitoring System For Turning Operation Using Acoustic Emission Signal Response And Factorial Design Method

This work discusses the generation of a quasi monitoring system intended for an operator to change cutting tool during turning operation. The monitoring system uses the effects of turning va riables on acoustic emission signal responses and factorial experimental design approach. In cutting operations, acoustic emission provides useful information concerning the tool wear condition because of the fundamental differences between its source mechanisms in the rubbing friction on the wear land of the single point tool. In this study, effects of cutting speed, feed and tool condition on the acoustic emission signal are investigated using acoustic emission's energy, amplitude, and frequency response and 23 factorial design for turning operation. Cutting tests were performed using high-speed steel under dry conditions. Calculated effects, standard errors at 95% confidence level, and models governing the acoustic emission response to the cutting conditions have been generated from the acoustic emission signal responses. The generated models revealed that acoustic energy response is affected by significant interactions between cutting speed and feed, and insignificant interactions between cutting speed and tool condition, while the acoustic amplitude response is affected by insignificant interactions among cutting speed, feed, and tool condition. These results suggest that acoustic emission's energy and amplitude responses could be used to control the cutting speed and feed during turning operation, thus prolonging the life of the cutting tool.Journal of Science & Technology (Ghana) Vol. 27 (2) 2007: pp. 107-12

Tackling Exascale Software Challenges in Molecular Dynamics Simulations with GROMACS

GROMACS is a widely used package for biomolecular simulation, and over the last two decades it has evolved from small-scale efficiency to advanced heterogeneous acceleration and multi-level parallelism targeting some of the largest supercomputers in the world. Here, we describe some of the ways we have been able to realize this through the use of parallelization on all levels, combined with a constant focus on absolute performance. Release 4.6 of GROMACS uses SIMD acceleration on a wide range of architectures, GPU offloading acceleration, and both OpenMP and MPI parallelism within and between nodes, respectively. The recent work on acceleration made it necessary to revisit the fundamental algorithms of molecular simulation, including the concept of neighborsearching, and we discuss the present and future challenges we see for exascale simulation - in particular a very fine-grained task parallelism. We also discuss the software management, code peer review and continuous integration testing required for a project of this complexity.Comment: EASC 2014 conference proceedin

Designing a Mechanical System That Will Be Used To Extract and Separate Lemon Grass Oil

ABSTRACT Lemon grass is broadly used in medicine, perfumery industry, vitamin A manufacturing and pharmaceuticals. The need for lemon grass oil, especially in human health and its problem of extracting the oil, have directed this paper in designing a mechanical system that will be used to extract and separate lemon grass oil. The extraction of essential oil from lemon grass was done using direct steam distillation process. In all, three concepts were developed based on the orientation of the condensers, source of power, and method of oil production. The three (3) concepts were evaluated and the best concept was selected as the final design. Design analysis was performed on each part to determine their specification, the material to be used and manufacturing processes for the fabrication. Two tests were performed to determine the performance of machine and the quality of the oil produced. From the results, it can be established that the prototype machine developed can be used to extract lemon grass oil from the leaves. The efficiencies were then computed and favorable results were obtained. Also, the results obtained for the four tests responded positive given an indication of the pureness of the oil. It can then be concluded that the prototype machine developed can be used to extract lemon grass oil from the leaves and its efficiency ranges from 2.37 to 3.95 ml/kg and it is economically viable, effective and efficient

Charge multiplication effect in thin diamond films

Herein, we report on the enhanced sensitivity for the detection of charged particles in single crystal chemical vapour deposition (scCVD) diamond radiation detectors. The experimental results demonstrate charge multiplication in thin planar diamond membrane detectors, upon impact of 18MeV O ions, under high electric field conditions. Avalanche multiplication is widely exploited in devices such as avalanche photo diodes, but has never before been reproducibly observed in intrinsic CVD diamond. Because enhanced sensitivity for charged particle detection is obtained for short charge drift lengths without dark counts, this effect could be further exploited in the development of sensors based on avalanche multiplication and radiation detectors with extreme radiation hardnes

Antiferromagnetic Order Induced by an Applied Magnetic Field in a High-Temperature Superconductor

One view of the cuprate high-transition temperature (high-Tc) superconductors is that they are conventional superconductors where the pairing occurs between weakly interacting quasiparticles, which stand in one-to-one correspondence with the electrons in ordinary metals - although the theory has to be pushed to its limit. An alternative view is that the electrons organize into collective textures (e.g. charge and spin stripes) which cannot be mapped onto the electrons in ordinary metals. The phase diagram, a complex function of various parameters (temperature, doping and magnetic field), should then be approached using quantum field theories of objects such as textures and strings, rather than point-like electrons. In an external magnetic field, magnetic flux penetrates type-II superconductors via vortices, each carrying one flux quantum. The vortices form lattices of resistive material embedded in the non-resistive superconductor and can reveal the nature of the ground state - e.g. a conventional metal or an ordered, striped phase - which would have appeared had superconductivity not intervened. Knowledge of this ground state clearly provides the most appropriate starting point for a pairing theory. Here we report that for one high-Tc superconductor, the applied field which imposes the vortex lattice, also induces antiferromagnetic order. Ordinary quasiparticle pictures cannot account for the nearly field-independent antiferromagnetic transition temperature revealed by our measurements

Rheumatoid synovial fluid interleukin-17-producing CD4 T cells have abundant tumor necrosis factor-alpha co-expression, but little interleukin-22 and interleukin-23R expression

Introduction\ud Th17 cells have been implicated in the pathogenesis of rheumatoid arthritis (RA). The aim of this study was to systematically analyse the phenotype, cytokine profile and frequency of interleukin-17 (IL-17) producing CD4-positive T cells in mononuclear cells isolated from peripheral blood, synovial fluid and synovial tissue of RA patients with established disease, and to correlate cell frequencies with disease activity. \ud \ud Methods\ud Flow cytometry was used to analyse the phenotype and cytokine production of mononuclear cells isolated from peripheral blood (PBMC) (n = 44), synovial fluid (SFMC) (n = 14) and synovium (SVMC) (n = 10) of RA patients and PBMC of healthy controls (n = 13). \ud \ud Results\ud The frequency of IL-17-producing CD4 T cells was elevated in RA SFMC compared with RA PBMC (P = 0.04). However, the frequency of this population in RA SVMC was comparable to that in paired RA PBMC. The percentage of IL-17-producing CD4 T cells coexpressing tumor necrosis factor alpha (TNFα) was significantly increased in SFMC (P = 0.0068). The frequency of IFNγ-producing CD4 T cells was also significantly higher in SFMC than paired PBMC (P = 0.042). The majority of IL-17-producing CD4 T cells coexpressed IFNγ. IL-17-producing CD4 T cells in RA PBMC and SFMC exhibited very little IL-22 or IL-23R coexpression. \ud \ud Conclusions\ud These findings demonstrate a modest enrichment of IL-17-producing CD4 T cells in RA SFMC compared to PBMC. Th17 cells in SFMC produce more TNFα than their PBMC counterparts, but are not a significant source of IL-22 and do not express IL-23R. However, the percentage of CD4 T cells which produce IL-17 in the rheumatoid joint is low, suggesting that other cells may be alternative sources of IL-17 within the joints of RA patients. \ud \u

IL-22 mediates goblet cell hyperplasia and worm expulsion in intestinal helminth infection.

Type 2 immune responses are essential in protection against intestinal helminth infections. In this study we show that IL-22, a cytokine important in defence against bacterial infections in the intestinal tract, is also a critical mediator of anti-helminth immunity. After infection with Nippostrongylus brasiliensis, a rodent hookworm, IL-22-deficient mice showed impaired worm expulsion despite normal levels of type 2 cytokine production. The impaired worm expulsion correlated with reduced goblet cell hyperplasia and reduced expression of goblet cell markers. We further confirmed our findings in a second nematode model, the murine whipworm Trichuris muris. T.muris infected IL-22-deficient mice had a similar phenotype to that seen in N.brasiliensis infection, with impaired worm expulsion and reduced goblet cell hyperplasia. Ex vivo and in vitro analysis demonstrated that IL-22 is able to directly induce the expression of several goblet cell markers, including mucins. Taken together, our findings reveal that IL-22 plays an important role in goblet cell activation, and thus, a key role in anti-helminth immunity