Dynamic Modelling of DNA Repair Pathway at the Molecular Level: A New Perspective

DNA is the genetic repository for all living organisms, and it is subject to constant changes caused by chemical and physical factors. Any change, if not repaired, erodes the genetic information and causes mutations and diseases. To ensure overall survival, robust DNA repair mechanisms and damage-bypass mechanisms have evolved to ensure that the DNA is constantly protected against potentially deleterious damage while maintaining its integrity. Not surprisingly, defects in DNA repair genes affect metabolic processes, and this can be seen in some types of cancer, where DNA repair pathways are disrupted and deregulated, resulting in genome instability. Mathematically modelling the complex network of genes and processes that make up the DNA repair network will not only provide insight into how cells recognise and react to mutations, but it may also reveal whether or not genes involved in the repair process can be controlled. Due to the complexity of this network and the need for a mathematical model and software platform to simulate different investigation scenarios, there must be an automatic way to convert this network into a mathematical model. In this paper, we present a topological analysis of one of the networks in DNA repair, specifically homologous recombination repair (HR). We propose a method for the automatic construction of a system of rate equations to describe network dynamics and present results of a numerical simulation of the model and model sensitivity analysis to the parameters. In the past, dynamic modelling and sensitivity analysis have been used to study the evolution of tumours in response to drugs in cancer medicine. However, automatic generation of a mathematical model and the study of its sensitivity to parameter have not been applied to research on the DNA repair network so far. Therefore, we present this application as an approach for medical research against cancer, since it could give insight into a possible approach with which central nodes of the networks and repair genes could be identified and controlled with the ultimate goal of aiding cancer therapy to fight the onset of cancer and its progression

ENTREPRENEURIAL EXPERIENCE, ENTREPRENEURIAL SELF-EFFICACY AND WIDOW ENTREPRENEURSHIP PERFORMANCE IN SOUTH EASTERN NIGERIA

Owing to the differences in the practice of entrepreneurship as occasioned by gender, culture and marital status, widow entrepreneurship ought to be studied separately. This is increasingly being re-echoed by the resilience of widow entrepreneurs in spite of the disinheritance, dehumanizing and discriminatory characteristics of the persisting widowhood practices in South Eastern Nigeria. This study therefore seeks to investigate the moderating role of entrepreneurial self-efficacy in the entrepreneurial experience, financial and non-financial performance of widow entrepreneurships in South Eastern Nigeria. The study adopts cross sectional research design and simple random sampling technique. The generated data via questionnaire were analyzed based on Baron and Kenny’s (1986) four step approach for testing moderation. It was found that entrepreneurial self-efficacy moderates the relationships. The researchers conclude that entrepreneurial self-efficacy can increase or decrease the strength of the relationship between entrepreneurial experience, and financial and non-financial performance of widow entrepreneurships in the long run

Vito Flaker@Boj za (2012): Direktno socialno delo, (Oranžna zbirka). Ljubljana: Založba /*cf. 372 str. ISBN 978-961-257-047-7

The yields of NO from combustion of bituminous coal, lignite, and biomass chars were investigated in O₂/N₂ and O₂/CO₂ atmospheres. The experiments were performed in a laboratory-scale fixed-bed reactor in the temperature range of 850–1150 °C. To minimize thermal deactivation during char preparation, the chars were generated by in situ pyrolysis at the reaction temperature. The NO yield clearly decreased and the CO yield increased when the atmosphere was altered from O₂/N₂ to O₂/CO₂ at 850 °C, but only small differences in NO and CO yields were observed between the two atmospheres at 1050–1150 °C. To examine how CO influences the NO yield, the effect of CO on NO reduction over char as well as NO reduction by CO over ash was investigated in the fixed-bed reactor. Furthermore, the influence of CO on the homogeneous oxidation of HCN, possibly a product of the char-N oxidation, was evaluated using a detailed chemical kinetic model. The results indicate that CO influences the NO yield from char combustion through two paths at 850 °C: (1) CO accelerates NO reduction over char and (2) CO accelerates HCN oxidation, increasing the possibility of NO reduction over char. Both effects were more pronounced at 850 °C than at 1050–1150 °C. The present work indicates that the effect of CO₂ on NO formation in oxy-fuel combustion in fluidized beds can partly be attributed to heterogeneous reactions, whereas for high-temperature pulverized fuel combustion, CO₂ mainly affects the volatile chemistry