Network conduciveness with application to the graph-coloring and independent-set optimization transitions

We introduce the notion of a network's conduciveness, a probabilistically interpretable measure of how the network's structure allows it to be conducive to roaming agents, in certain conditions, from one portion of the network to another. We exemplify its use through an application to the two problems in combinatorial optimization that, given an undirected graph, ask that its so-called chromatic and independence numbers be found. Though NP-hard, when solved on sequences of expanding random graphs there appear marked transitions at which optimal solutions can be obtained substantially more easily than right before them. We demonstrate that these phenomena can be understood by resorting to the network that represents the solution space of the problems for each graph and examining its conduciveness between the non-optimal solutions and the optimal ones. At the said transitions, this network becomes strikingly more conducive in the direction of the optimal solutions than it was just before them, while at the same time becoming less conducive in the opposite direction. We believe that, besides becoming useful also in other areas in which network theory has a role to play, network conduciveness may become instrumental in helping clarify further issues related to NP-hardness that remain poorly understood

Methylation of CpG island is not a ubiquitous mechanism for the loss of oestrogen receptor in breast cancer cells.

Methylation has been shown to play an important role in the down-regulation of oestrogen receptors (ER) in breast cancer cells. One critical question that remains unclear is whether methylation can account for the loss of ER expression in cells derived from an ER-positive cell line. This laboratory has established an in vitro cell system using long-term growth of human ER-positive breast cancer cell line T47D in oestrogen-free medium. A clonal cell line, T47D:C4:2 (C4:2), has been characterized. Unlike T47D:A18 (A18), which is a T47D line maintained in oestrogen medium, C4:2 has lost the expression of ER and hormone responsiveness. DNA fingerprinting and restriction fragment length polymorphism (RFLP) analysis results confirmed that C4:2 was of the same lineage as A18. These cell lines provide an invaluable system to study the mechanism of ER expression and regulatory pathways leading to hormone-independent growth. The results here clearly demonstrate that the ER CpG island in C4:2 cells remains unmethylated. The loss of ER in the cell line must be due to mechanisms other than methylation. We also evaluated the ER CpG island in the MDA-MB-231:10A (10A) cell line, which is a clone from the MDA-MB-231 line obtained from ATCC and the DNA from the MDA-MB-231 cell line used in the original report. Unlike the cell line from the report, which showed a full methylation pattern in the island, the 10A line only showed a partial methylation pattern in the CpG island. Possible mechanisms pertaining to the heterogeneous methylation pattern of the ER CpG island in the breast cancer cells are discussed

Human cytomegalovirus (HCMV) replication dynamics in HCMV-naive and -experienced immunocompromised hosts

Human cytomegalovirus (HCMV) can infect both HCMV-naive and -experienced transplant patients. In this study, the growth rate of HCMV in HCMV-naive hosts (1.82 units/day; 95% confidence interval [CI], 1.44-2.56 units/day) was shown to be significantly faster than the growth rate of virus in HCMV-experienced hosts undergoing recurrent infection (0.61 units/ day; 95% CI, 0.55-0.7 units/day; P93% (95% CI, 89%-98%) is required to eliminate viral growth during infection of HCMV-naive liver transplant recipients, whereas lower efficacy levels are sufficient to reduce the R-0 value to <1 in hosts with prior HCMV immunity

Modeling the role of oxygen vacancy on ferroelectric properties in thin films

2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Energy landscapes and urban trajectories towards sustainability

An urban energy transition is needed to address the two global environmental challenges of urbanisation and increasing carbon emissions. Urban energy landscapes represent the spatial patterns of urban energy systems which are visible in the built environment. Spatial regularities in the way systems of energy provision and use are organised are manifest in urban energy landscapes. Energy uses may vary in relation to the structures of the built environment, and the perceptions that coevolve with technologies.This paper presents evidence from three case studies of urban energy landscapes in Hong Kong (PRC), Bengaluru (India) and Maputo (Mozambique). The cases suggest a variety of patterns (uniform, fragmented, scattered) in terms of how different fuels and electricity are provided and who has access to them. Qualitative research among policy makers reveals different trajectories towards sustainability. The paper concludes with the suggestion that the spatial organisation of urban energy systems shapes potential trajectories of change for an urban energy transition. This would call for forms of spatial planning that promote flexibility as a means to foster sustainability innovations. However, further evidence will be required to evaluate whether this exploratory analysis can be generalised beyond the three cities studied

The Promotion of Drug Abuse - PO*

The problem of drug abuse is both international and multifactorial. Traditional approaches toward finding a solution have so far achieved little. Lateral thinking, a recent concept providing freedom from the constraints of logic, offers the basis for a different kind of evaluation of the problem. The normal concepts are reversed and one starts with the proposition of promoting  drug abuse. In defining a promotional programme one becomes increasingly aware of those elements which are important contributory factors. The solution to some parts of the problem becomes self-evident and new insights into other facets are suggested.S. Afr. Med. J., 48, 407 (1974

A Semantic and Pragmatic Analyses of Igbo Names

The paper investigated the semantic and pragmatic contents of personal names and naming in the Igbo language and culture. The objective of the paper was to examine the structure of Igbo names and analyse their semantic and pragmatic contents. The data were sourced from Igbo language speakers in the South Eastern States of Nigeria. The data cut across Standard and dialectal Igbo names. Selected personal names were grouped structurally according to their forms in the following order: lexical (or mono-morphemic) names, Noun-Noun phrasal names, Noun-Verb phrasal names, Noun-Verb Phrasal-Complement/Sentential names and Interrogation/Injunction names. The semantic and pragmatic analyses were made based on the structural data generated. The pragmatic analysis was handled by incorporating the context into the semantic contents. Findings showed that Igbo names structurally fall into three broad categories: lexical, phrasal and sentential. For Ndigbo, a name is not just a tag of identity or personal label but a story and an expression of the events and circumstances surrounding the birth of the child as well as the parents’ life experiences and world view.Keywords: personal names, Igbo, semantic content, pragmatic content, structur

The neurotic Christian: implications for Christian ministry in Nigeria

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A contrastive study of two varieties of Onicha and the Central Igbo language

He crux of this paper is to compare the Onicha and the Central Igbo varieties of the Igbo language. Igbo is a language spoken in south eastern Nigeria, precisely in the present Abia, Anambra, Ebonyi, Enugu, and Imo states. It is the sole language of the Igbo ethnic group of the south east states. Igbo is also a minority language of the people of Delta, Rivers, and Edo states in the present south-south geopolitical zone. It is fraught with numerous dialects which can be arranged in clusters. Some Igbo linguists recognize merely two major dialect areas, namely Onicha (Onitsha) and Owere (Owerri) on which this study is based. The objective of the paper is to present the morphosyntactic and phonological analyses of the two lects (by comparing them) in order to highlight their similarities and differences. It is observed that there are variations in the speech forms of the Central and the Onicha Igbo varieties. These variations are attested both in the lexical and the morphosyntactic domains