Natural convection past inclined porous layers

Combined Rayleigh-​Benard convection and Tollmien-​Schlichting type of instability of a fluid in an inclined layer bounded by 2 permeable bed was studied. Several types of flow, depending on the value of the Prandtl no., Pr, were studied using a fast-​convergent-​power series technique. Two different convective movements, longitudinal and transverse rolls, based on different Pr, are reported. The effect of slip at the nominal surface is to augment the instability and change the crit. Grashof no., Gr, and crit. Rayleigh no., Ra, markedly for small permeability parameter σ, being independent of Gr and Ra for large σ. The effect of inclination φ is to inhibit the onset of instability in the case of air and to augment it in the case of Hg. At max. inclination (i.e., φ = π​/2)​, the instability sets in as transverse rolls, irresp. of the value of Pr. In the case of Hg, the transverse rolls exist for all φ, whereas in the case of air, they are limited only to certain φ. The cell pattern changes dramatically in the range φ = π​/6 to π​/4

Simulating microbial degradation of organic matter in a simple porous system using the 3-D diffusion-based model MOSAIC

This paper deals with the simulation of microbial degradation of organic matter in soil within the pore space at a microscopic scale. Pore space was analysed with micro-computed tomography and described using a sphere network coming from a geometrical modelling algorithm. The biological model was improved regarding previous work in order to include the transformation of dissolved organic compounds and diffusion processes. We tested our model using experimental results of a simple substrate decomposition experiment (fructose) within a simple medium (sand) in the presence of different bacterial strains. Separate incubations were carried out in microcosms using five different bacterial communities at two different water potentials of −10 and −100 cm of water. We calibrated the biological parameters by means of experimental data obtained at high water content, and we tested the model without changing any parameters at low water content. Same as for the experimental data, our simulation results showed that the decrease in water content caused a decrease of mineralization rate. The model was able to simulate the decrease of connectivity between substrate and microorganism due the decrease of water content

Is country branding a panacea or poison?

The momentum towards complete globalisation advocated by proponents of the benefits of one big business village as the answer to the suffering of third world countries, has now been slowed down by the uncertainty resultant from the hitherto unprecedented global meltdown. With the coughing of America, the whole world seems to be catapulting into one big mess due to the global economic quagmire. Consequently, there is a global scramble for the limited and constantly contracting financial and market resources. Third world countries, rich in natural resources but insignificant global players, have been relegated to perpetual recipients of aid, finished products and obsolete or second rate technology. Despite having 53 countries, Africa is painted en bloc as a “dark continent” dogged by civil wars, disease, poverty and famine. This “bad continent” image thus affects all African countries including those that are fairly stable such as South Africa, Botswana, and Egypt. This scenario necessitates country differentiation through individualised or regionalised country branding

Police brutality in post-apartheid South Africa reviewed

The objective of this paper was to revisit the issue of police brutality in post-apartheid South Africa, since it has recently become a highly contextual topic with polarising views. Some individuals have tried to justify the level of brutality by the South African Police Service, while others disagree with these views and perceive the issue as problematic. Apart from the literature review, questionnaires where formulated distributed to twenty individuals from the general public, in order to ascertain their perception regarding the issue. This questionnaire was structured in a way that would allow the individuals to not only state their opinion regarding the different aspects of the South African Police Service but to also enable the respondent to elaborate on their reasoning. The finding from the feedback obtained from ten respondents reveal that police brutality is perceived as a major problem in South Africa, and most individuals are perturb by the current state of affairs. However, they feel very helpless in their ability to change the situation. Some respondents feel that it is only people in top positions in the police hierarchy or government that could influence the change that is required to improve the situation, in order to enhance the image of the South African Police Services, in such a way that communities could perceive them more as friends rather than enemies

Value Creation in B2B E-Markets of China: A Practical Perspective

In China, the development of e-market has unique characteristics in the transactional processes and market mechanisms, which relate largely to the current industry structure, financial infrastructure and organization structure. This paper seeks to develop a conceptual model of B2B e-market value creation strategy, and can also be used to highlight the complexity of such activities for Chinese B2B e-markets. A process-oriented approach to modelling the value of e-market, rather than strategic position theory or a simple descriptive approach, is found to be more suitable and has been selected. The model consists of two dimensions: the e-commerce process and the controlling complexity. We apply the model in an actual Chinese B2B e-market (Alibaba.com). The crucial value creation activities and strategies in the four phases of e-commerce process are identified, and the controlling complexity of these activities is evaluated in the model. The model offers an effective approach to study the dynamic structure of transactional processes and bring into light the special issues of e-market development in China. Managers can resort to the model to offer more value to their customers by designing an effective e-market process

Depletion-mode Quantum Dots in Intrinsic Silicon

We report the fabrication and electrical characterization of depletion-mode quantum dots in a two-dimensional hole gas (2DHG) in intrinsic silicon. We use fixed charge in a SiO$_2$/Al$_2$O$_3$ dielectric stack to induce a 2DHG at the Si/SiO$_2$ interface. Fabrication of the gate structures is accomplished with a single layer metallization process. Transport spectroscopy reveals regular Coulomb oscillations with charging energies of 10-15 meV and 3-5 meV for the few- and many-hole regimes, respectively. This depletion-mode design avoids complex multilayer architectures requiring precision alignment, and allows to adopt directly best practices already developed for depletion dots in other material systems. We also demonstrate a method to deactivate fixed charge in the SiO$_2$/Al$_2$O$_3$ dielectric stack using deep ultraviolet light, which may become an important procedure to avoid unwanted 2DHG build-up in Si MOS quantum bits.Comment: Accepted to Applied Physics Letters. 5 pages, 3 figure

Does Oline Video-Sharing Advertising Have Diffusion Gene?

Video-sharing is one of the most popular applications on the Internet, the development of which subverts the traditional information diffusion path. Online video-sharing advertising emerges quickly at the same time. Quick online video sharing and diffusing of advertising depend heavily on its presentation of entertainment content and its display format. This article classifies the entertainment content of online video-sharing advertising (VSA) into humor and funny content (HFC), focus event content (FEC), and sex and nudity content (SNC); and presents the display format of online VSA into real format and anthropomorphic format. Hence, this article has conducted a research on the possible relationship between these two factors and how they influence the effects of online video-sharing advertising. This experimental study confirms that entertainment content and display format are the most critical factors to audiences in sharing and diffusing the online VSA. It also finds out that if advertisers use HFC as the entertainment content of online VSA, the best display format of online VSA is the realistic format; and if advertisers use SNC as the entertainment content of online VSA, the best display format of online VSA is the anthropomorphic format

Cytosolic calcium and protein kinase C reduce complement-mediated glomerular epithelial injury

Cytosolic calcium and protein kinase C reduce complement-mediated glomerular epithelial injury. In rat membranous nephropathy, proteinuria is due to formation of the C5b-9 membrane attack complex of complement (C), and is associated with morphological evidence of glomerular epithelial cell (GEC) injury. Analogous morphological changes are induced by C5b-9 in cultured GEC. In addition, in cultured GEC C5b-9 induces Ca2+ influx, as well as Ca2+ mobilization and increased 1,2-diacylglycerol due to the activation of phospholipase C. In this study we investigated how this GEC activation pattern might influence C-mecliated GEC injury. We demonstrate that the C5b-9-induced increase in cytosolic Ca2+ concentration ([Ca2+]i) did not impair ATP generation by mitochondria, suggesting that it does not contribute to cytotoxicity. Moreover, this increase in [Ca2+]i protected GEC from C-mediated cytolysis. However, a large increase in [Ca2+]i (produced by the Ca2+ ionophore A23187) impaired ATP generation and aggravated C-mediated cytotoxicity, suggesting that intact mitochondrial activity is necessary for GEC to withstand C attack. Activation of protein kinase C (PKC) by phorbol myristate acetate (PMA) also decreased C-mediated cytolysis. Conversely, C lysis was enhanced in GEC that had been pretreated for 18 hours with a high dose of PMA to deplete PKC, and following PKC inhibition with H-7. Therefore, PKC activation, possibly resulting from C5b-9-induced increase in 1,2-diacylglycerol, triggered mechanisms that protected GEC from C-mediated injury. Thus, as a consequence of C5b-9-induced phospholipase activation, the amount of C-induced GEC injury is diminished

The effects of the protozoan fauna of trickling filter ballast upon salmonella species

Call number: LD2668 .T4 1953 C4Master of SciencePlant Patholog