Fibonacci type semigroups

We study "Fibonacci type" groups and semigroups. By establishing asphericity of their presentations we show that many of the groups are infinite. We combine this with Adjan graph techniques and the classification of the finite Fibonacci semigroups (in terms of the finite Fibonacci groups) to extend it to the Fibonacci type semigroups

Many Strokes of the Lash: André Duval

Vincent de Paul held Andre Duval in high esteem as a holy man. Duval helped him see that starting the Congregation was God’s will. Vincent often consulted him, so much so that Duval “became a sort of theologian and canonist” for the Congregation. His life, career, and relationships with Pierre de Berulle and Vincent are treated here. Duval taught theology at the Sorbonne and was influential in the establishment of the Reformed Carmelites and in the reform of many other religious orders and institutes. His views on papal authority came to be known as Duvalism and were well received. He was a leader of the Catholic Restoration in France

Geodetic precession and frame dragging observed far from massive objects and close to a gyroscope

Total precession (geodetic precession and frame dragging) depends on the velocity of each source of gravitation, which means that it depends on the choice of the coordinate system. We consider the latter as an anomaly specifically in the Gravity Probe B experiment, we investigated it and solved this anomaly. Thus, we proved that if our present expression for the geodetic precession is correct, then the frame dragging should be 25% less than its predicted value.Comment: 11 page

Academic research and HIV/AIDS in South Africa

No Abstract

Coupled probabilistic and point kinetics modelling of fast pulses in nuclear systems

AbstractThis paper describes a probabilistic method of modelling point nuclear systems with low numbers of neutrons including the effects of delayed neutron precursors and its coupling with standard point kinetics equations. This coupling allows the simulation of the non-deterministic progression of a system transitioning from subcritical to supercritical and the resulting power peak. Through analysis of large numbers of realisations various statistical parameters of such transients can be obtained. The method of simulation presented here successfully replicates the survival and extinction probabilities predicted by the Backwards Master Equation and experimental and analytic results from the literature regarding the Godiva reactor and extends the examination of that reactor. In particular the effect of delayed neutrons on the simulated response of Godiva is highlighted. With its implementation in a parallel computer code, the model is able to simulate at a reasonable speed a range of systems where low neutron populations are important

Practice pointer: Using the new UK-WHO growth charts

The new UK growth charts for children aged 0-4 years (designed using data from the new WHO standards) describe the optimal pattern of growth for all children, rather than the prevailing pattern in the UK (as with previous charts). The new charts are suitable for all ethnic groups and set breast feeding as the norm. UK children match the new charts well for length and height, but after age 6 months fewer children will be below the 2nd centile for weight or show weight faltering, and more will be above the 98th centile. The new charts look different: they have a separate preterm section, no lines between 0 and 2 weeks, and the 50th percentile is no longer emphasised. The charts give clear instructions on gestational correction, and there is a new chart for infants born before 32 weeks’ gestation. The instructions advise on when and how to measure and when a measurement or growth pattern is outside the normal range. The charts include a “look-up” tool for determining the body mass index centile from height and weight centiles without calculation and aid for predicting adult height. The charts and supporting educational materials can be downloaded from www.growthcharts.rcpch.ac.u

Data Analysis and Robust Modelling of the Impact of Renewable Generation on Long Term Security of Supply and Demand

This paper studies rigorous statistical techniques for modelling long term reliability of demand and supply of electrical power given uncertain variability in the generation and availability of wind power and conventional generation. In doing so, we take care to validate statistical assumptions, using historical observations, as well as our intuition about the actual underlying real-world statistical process. Where assumptions could not be easily validated, we say so explicitly. In particular, we aim to improve existing statistical models through sensitivity analysis of ill-known parameters: we propose models for wind power and conventional generation, estimate their parameters from historical wind power data and conventional availability data, and finally combine them with historical demand data to build a full robust joint time-dependent model of energy not served. Bounds on some useful indices from this model are then calculated, such as expected energy not served, and expected number of continuous outage periods-the latter cannot be estimated from a purely time collapsed model because time collapsed models necessarily do not model correlations across time. We compare our careful model with a naive model that ignores deviations from normality, and find that this results in substantial differences: in this specific study, the naive model overestimates the risk roughly by a factor 2. This justifies the care and caution by which model assumptions must be verified, and the effort that must be taken to adapt the model accordingly

Sustainablility of Agricultural Transformation Agenda: The Place of Rice Farmers in Ogun State, Nigeria

Self-sufficiency in rice production and processing has eluded Nigeria for a long time despite continuous efforts by the Federal Government of Nigeria towards its realization. Chains of activities in the Nigerian rice production and processing industry are largely executed manually and on small scale level. Thus, the issues of value chain aspects that would have improved the profitability of the rice industry have only just been taken into consideration as part of the Presidential Initiative – Agricultural Transformation Agenda (ATA).This study examines the prospect of Agricultural Transformation Agenda amongst rice farmers in Ogun State where rice production is a growing industry in attempt to achieve food sustainability in line with the Agricultural Transformation Agenda. Well-structured and validated questionnaires are used to survey and report the activities and processes carried out by the rice farmers in target area. However, part of the result of the survey indicated that the level of awareness of Agricultural Transformation Agenda is still very low in the study area. There is need for a conscious and concerted effort to be made by relative Government Agencies to create greater awareness about ATA for the rice farmers and others involved in empowering the growth of the rice industry, otherwise the vision and motives of Agricultural Transformation Agenda may remain just an academic exercise. Other Government Agricultural Policy, for example the Fadama and/or Ogun State Agricultural Development (OGADEP )  were well accepted and their impact is greatly significant in the study area which is a clear indication that ATA strategies like the above-named policies would be well adopted by the rice farmers as well as those related participants like the processing and marketing aspects of the industry if the gospel of Agricultural Transformation Agenda is effectively preached to the rice farmers in the study area.   Key words: Rice industry, Small holder farms, Family labour, Agricultural Transformation Agenda, Government Agricultural Policy, Ogun State, Nigeria

Reorientation of magnetic anisotropy in epitaxial cobalt ferrite thin films

Spin reorientation has been observed in CoFe2O4 thin single crystalline films epitaxially grown on (100) MgO substrate upon varying the film thickness. The critical thickness for such a spin-reorientation transition was estimated to be 300 nm. The reorientation is driven by a structural transition in the film from a tetragonal to cubic symmetry. At low thickness, the in-plane tensile stress induces a tetragonal distortion of the lattice that generates a perpendicular anisotropy, large enough to overcome the shape anisotropy and to stabilize the magnetization easy axis out of plane. However, in thicker films, the lattice relaxation toward the cubic structure of the bulk allows the shape anisotropy to force the magnetization to be in plane aligned

Gravitation and inertia; a rearrangement of vacuum in gravity

We address the gravitation and inertia in the framework of 'general gauge principle', which accounts for 'gravitation gauge group' generated by hidden local internal symmetry implemented on the flat space. We connect this group to nonlinear realization of the Lie group of 'distortion' of local internal properties of six-dimensional flat space, which is assumed as a toy model underlying four-dimensional Minkowski space. The agreement between proposed gravitational theory and available observational verifications is satisfactory. We construct relativistic field theory of inertia and derive the relativistic law of inertia. This theory furnishes justification for introduction of the Principle of Equivalence. We address the rearrangement of vacuum state in gravity resulting from these ideas.Comment: 17 pages, no figures, revtex4, Accepted for publication in Astrophys. Space Sc