Trust realisation in multi-domain collaborative environments

In the Internet-age, the geographical boundaries that have previously impinged upon inter-organisational collaborations have become decreasingly important. Of more importance for such collaborations is the notion and subsequent nature of trust - this is especially so in Grid-like environments where resources are both made available and subsequently accessed and used by remote users from a multitude of institutions with a variety of different privileges spanning across the collaborating resources. In this context, the ability to dynamically negotiate and subsequently enforce security policies driven by various levels of inter-organisational trust is essential. In this paper we present a dynamic trust negotiation (DTN) model and associated prototype implementation showing the benefits and limitations DTN incurs in supporting n-tier delegation hops needed for trust realisation in multi-domain collaborative environments

Characterisation of multiple substrate-specific (d)ITP/(d)XTPase and modelling of deaminated purine nucleotide metabolism

To be viable, organisms possess a number of (deoxy)nucleotide phosphohydrolases, which hydrolyze these nucleotides removing them from the active NTP and dNTP pools. Deamination of purine bases can result in accumulation of such nucleotides as ITP, dITP, XTP and dXTP. E. coli RdgB has been characterised as a deoxyribonucleoside triphosphate pyrophosphohydrolase that can act on these nucleotides. S. cerevisiae homologue encoded by YJR069C was purified and its (d)NTPase activity was assayed using fifteen nucleotide substrates. ITP, dITP, and XTP were identified as major substrates and kinetic parameters measured. Inhibition by ATP, dATP and GTP were established. On the basis of experimental and published data, modelling and simulation of ITP, dITP, XTP and dXTP metabolism was performed. (d)ITP/(d)XTPase is a new example of enzyme with multiple substrate-specificity demonstrating that multispecificity is not a rare phenomenon

Antioxidant Properties of Albizia lebbeck Seed Protein Hydrolysates

Peptide based antioxidants from plant and animal proteins are being identified as food additives and also as potential alternatives in the reduction of oxidative stress. This study investigated the antioxidative potentials of peptide digests of Albizia lebbeck seed protein. The proteins were extracted and isolated from A. lebbeck by defatting with n-hexane, followed by alkaline solubilization and acid precipitation of the seed meal. The protein isolate was then subjected to enzymatic hydrolysis using four proteases – pepsin, trypsin, papain and chymotrypsin. The resulting hydrolysates were then evaluated for their abilities to reduce ferric ions, as well as their effects on hydroxyl radicals, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide radicals. Hydrolysates obtained from peptic proteolysis demonstrated the best activities against DPPH radical and ferric ions (57.589 ± 1.286% and 52.000 ± 0.589 mM Fe2+ respectively), whereas chymotrypsin hydrolysates scavenged superoxide radicals and hydroxyl radicals better than other protein digests (74.520 ± 0.998% and 36.925 ± 1.880% respectively). The choice of enzyme used and the presence of specific amino acid residues at certain positions of peptides in the hydrolysates influenced their antioxidant capacities. It is concluded that Albizia lebbeck seed proteins encode potentially bioactive peptides, which could be harnessed for numerous therapeutic and nutraceutical benefits

The design and synthesis of peptide/protein based ATRP initiators

A series of novel hetero-bifunctional linkers functionalised as ATRP initiators and protein and peptide-reactive agents has been prepared using standard synthetic techniques. A protein-based initiator has been applied to the initiation of living polymerisation in the synthesis of a novel bioconjugate. The linkers were designed based on the properties of polyethylene glycol and short alkyl chains coupled to either amine selective or thiol selective moieties for chemoselectivity, and bromoisobutyryl esters to facilitate atom transfer living polymerisation. The bi-functional linkers have also been coupled to short peptides based on the RGD bio-recognition sequence synthesised by standard solid phase peptide synthesis and the protein. Human Serum Albumin (HSA) using standard conditions to prepare peptide/protein-based ATRP initiators. Attempts at functionalising peptides with the N succinimidyl 4-(2-bromo-2- methylpropionyloxy) butanoate linker were unsuccessful. Model test of the protein based ATRP initiators in living polymerisation towards a novel strategy for bioconjugate synthesis was inconclusive as premature termination of the polymer chain was observed by MALDI analysis

Urbanization, Housing Quality and Health: Towards a Redirection for Housing Provision in Nigeria

Nigeria’s housing provision is perceived in terms of quantity with less attention to its quality and impact on people’s health. The quality of indoor air in housing and its associated risks to human health was assessed in this paper to improve housing provision in Nigeria. Quantitative data collected from Bauchi, Nigeria includes household surveys, housing characteristics, indoor carbon dioxide (CO2), and particulate matter (PM2.5 and PM10). PM2.5 and PM10 recorded in the building were (63 μm/m3) and (228 μm/m3) and observed to be greater than safe values of 25 μm/m3 (PM2.5) and 50 μm/m3 (PM10) recommended by the World Health Organization (WHO). Some building features associated with some ailments were found to be risk factors. The study recommended a redirection for more quality housing provision. It concludes that housing characteristics should be targeted for public health interventions as a means of improving the quality of urban housing in Nigeria.

Genetic variation among active and inactive transmitters of Maize streak virus within a population of Cicadulina storeyi China (Homoptera: Cicadellidae)

This study was undertaken to delineate active transmitters from inactive ones within a population of Cicadulina storeyi China, vector of Maize streak virus (MSV), genus Mastrevirus using Mendelian crosses, random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) and isozyme esterase analysis. This study indicated that the variation is genetic. Four out of six Mendelian crosses perfectly fitted the expected ratio. Molecular studies with random amplified polymorphic DNA (RAPD)-PCR and isozymic studies with esterase analysis showed significant polymorphism and were useful to separate active and inactive transmitters within C. storeyi population. MSV was detected within the vectors through PCR and ICPCR. IC-PCR was used to show that there was no difference in the distribution of MSV within active and inactive C. storeyi as the virus was detected in the head, thorax and abdomen of active and inactive transmitters.Key words: Cicadulina stroreyi, crosses, active/inactive transmitters, polymorphism

Intelligent voltage dip mitigation in power networks with distributed generation

Includes bibliographical references.The need for ensuring good power quality (PQ) cannot be over-emphasized in electrical power system operation and management. PQ problem is associated with any electrical distribution and utilization system that experiences any voltage, current or frequency deviation from normal operation. In the current power and energy scenario, voltage-related PQ disturbances like voltage dips are a fact which cannot be eliminated from electrical power systems since electrical faults, and disturbances are stochastic in nature. Voltage dip tends to lead to malfunction or shut down of costly and mandatory equipment and appliances in consumers’ systems causing significant financial losses for domestic, commercial and industrial consumers. It accounts for the disruption of both the performance and operation of sensitive electrical and electronic equipment, which reduces the efficiency and the productivity of power utilities and consumers across the globe. Voltage dips are usually experienced as a result of short duration reduction in the r.m.s. (r.m.s.- root mean square) value of the declared or nominal voltage at the power frequency and is usually followed by recovery of the voltage dip after few seconds. The IEEE recommended practice for monitoring electric power quality (IEEE Std. 1159-2009, revised version of June 2009), provides definitions to label an r.m.s. voltage disturbance based upon its duration and voltage magnitude. These disturbances can be classified into transient events such as voltage dips, swells and spikes. Other long duration r.m.s. voltage variations are mains failures, interruption, harmonic voltage distortion and steady-state overvoltages and undervoltages. This PhD research work deals with voltage dip phenomena only. Initially, the present power network was not designed to accommodate renewable distributed generation (RDG) units. The advent and deployment of RDG over recent years and high penetration of RDG has made the power network more complex and vulnerable to PQ disturbances. It is a well-known fact that the degree of newly introduced RDG has increased rapidly and growing further because of several reasons, which include the need to reduce environmental pollution and global warming caused by emission of carbon particles and greenhouse gases, alleviating transmission congestion and loss reduction. RDG ancillary services support especially voltage and reactive power support in electricity networks are currently being recognized, researched and found to be quite useful in voltage dip mitigation

Love beyond colour : the formation of interracial gay men's intimate relationships in post-apartheid South Africa

South Africa became the first country in Africa to legalise same-sex marriages in its post-apartheid constitution. The formally instituted racial and sexual discriminations that dominated during the apartheid period were revised and equality of all citizens, irrespective of their race and sexual orientations, represents one of the key achievements of democratic South Africa. The current constitution gives room for people to express their sexualities freely without being discriminated against. This recognition is bridging the gap of racial and sexual exclusion and inclusion that were created during and before the apartheid era. Despite the everyday negative experiences of gay men based on their sexual orientation in post-apartheid Sou! th Africa, gay partners persist in their intimate relationships and continue to negotiate their social and constitutional rights. What is interesting at the moment is the increasing visibility of interracial gay partners in this country as a whole. This paper explores how a small group of men of different racial backgrounds assert their constitutional rights through the formation of interracial same-sex intimate relationships that used to be a criminal offence