Multi-step Richardson-Romberg Extrapolation: Remarks on Variance Control and complexity

We propose a multi-step Richardson-Romberg extrapolation method for the computation of expectations $E f(X_{_T})$ of a diffusion $(X_t)_{t\in [0,T]}$ when the weak time discretization error induced by the Euler scheme admits an expansion at an order $R\ge 2$. The complexity of the estimator grows as $R^2$ (instead of $2^R$) and its variance is asymptotically controlled by considering some consistent Brownian increments in the underlying Euler schemes. Some Monte carlo simulations carried with path-dependent options (lookback, barriers) which support the conjecture that their weak time discretization error also admits an expansion (in a different scale). Then an appropriate Richardson-Romberg extrapolation seems to outperform the Euler scheme with Brownian bridge.Comment: 28 pages, \`a para\^itre dans Monte Carlo Methods and Applications Journa

Inhibition of bio corrosion of steel coupon by sulphate reducing bacteria and Iron oxidizing bacteria using Aloe Vera (Aloe barbadensis) extracts

The inhibition of biocorrosion of steel coupons by sulphate reducing bacteria (SRB) and Iron oxidizing bacteria (IOB) using Aloe vera (Aloe barbadensis) extract was tested. The water sample revealed a heterotrophic bacterial count of 1.7x103 cfu/ml for the sulphate reducing bacteria and 4.1x103 cfu/ml for the Iron oxidizing bacteria. Biocorrosion inhibition test using Aloe vera extract was prepared with 50 % w/v stock solution at 10 %, 20 %, 40 % and 80 % (v/v) concentrations. An increase in acidity was observed in the fresh post gate medium after 7 days to 6.6 with a slight drop to 6.5 after 28 days in the setup with SRB. In contrast, the pH of the setups with IOB showed an increase in alkalinity from 6.8 in fresh Winogradsky medium to 7.4 after 7 days. The conductivity of SRB setup increased from 3150 μS/cm to 27100 μS/cm after 7 days and decreased to 200 μS/cm after 28 days. On the other hand, the IOB setup showed an increase in conductivity from 100 μS/cm to 2820 μS/cm after 28 days. The surfaces of the metal coupon used in the biocorrosion testing were slimy to touch, indicating possible biofilm production. The average corrosion rate from day 7 to day 28 for IOB and SRB are 6.606 mpy and 12.48 mpy respectively. The 80 % v/v concentration of Aloe vera extract gave the highest inhibition efficiency, ranging from 89 %-100 % for IOB and 66 %- 100 % for SRB. Aloe vera extract inhibited corrosion of steel coupons mediated by aerobic iron oxidizing bacteria and anaerobic sulphate reducing bacteria.Keywords: Aloe Vera extract, biocorrosion, metal coupons, oxidizing bacteria, reducing bacteri

Beyond locutionary denotations: exploring trust between practitioners and policy

This study reports the findings of a research on the trust relationship between practitioners in the Skills for Life (SfL) area and the policy that informs their practice. The exploration of this relationship was premised on an extended notion of trust relationship which draws from the Speech Act theory of Austin (1962; Searle 1969; Kissine 2008), leading to the claim that the existence of different layers of imports in textual analysis makes it possible for a trust relationship to exist between the human/physical and the non human/non physical. The study found that the majority of practitioners in the SfL field trust policy to deliver its inherent policy only to a limited extent. Amongst others, the study identified the impact of the perlocutionary import of policy text on practitioners as a viable reason for this limited level of trust. Such perlocutionary imports, it also found, have adverse impact on practitioners who are considered to have drawn from previous experience to mediate the import of contemporary policies

The comparison between cytological and histological grading of breast cancers in a Nigerian tertiary hospital

Background: Breast cancer is one of the most common cancers in Nigeria. The tumour grade is an important prognostic factor and is also important in treatment of patients. Fine needle aspiration cytology can be used as an initial diagnostic tool for planning definitive management. Grading of tumours on cytology further guides therapeutic decisions. The aim of this study is to compare the correlation between the cytological and histological grading of malignant breast lumps using the Robinson's cytological grading system and Nottingham histological grading system respectively. The Objectives are, to determine the age distribution of breast cancer in our environment, to grade breast cancers cytologically using the Robinson's cytological grading system and to grade breast cancers histologically using the Nottingham histological grading system.Methods: This was a one year prospective study that involved 30 patients who had malignant smears on fine needle aspiration cytology of their breast lump. These smears were graded using the Robinson's cytological grading system and compared with the Nottingham histological grading systems of same lumps obtained from either tissue biopsies or mastectomies.Results: The mean age of the study participants was 50.23±10.11 years with a range of 35-70 years. Most (56.7%) malignat smears were of cytologic grade 3. The histological grade was 2 in 16(53.3%) and 3 in 14(46.7%) of the same breast tissue samples. The grade 2 tumours had the highest concordance rate of 83.3%. The absolute concordance rate between Robinson's cytological and Nottingham histological grading system of breast cancers was 73.3%.Conclusion: The Robinson's cytological and Nottingham histological grading systems showed good correlation.Keywords: Breast Cancer, fine needle aspiration cytology, cytological grading, histological gradin

COUNSELLING INTERVENTIONS FOR THE SPECIAL NEEDS STUDENTS IN SECONDARY SCHOOLS IN EKITI STATE

The purpose of this study was to find the counselling interventions for the Special Needs Students in some Secondary Schools in Ekiti State. Three research questions and three hypotheses were formulated for the study. A self constructed instrument is titled “Counselling Interventions for the Special Needs Students” was used for the study. A sample of fifty two respondents was selected using purposive sampling technique. Data were analysed using descriptive and inferential statistics. Results showed that there is no significant difference in terms of class and age but there is difference on the basis of gender on counselling interventions for the special needs students in Ekiti State. Recommendations were made to government, corporate bodies, teachers, counsellors, parents and individual which would enable them develop in order to achieve a high level of self sufficiency and not to be at the mercy of inadequate support services

Effect of aqueous extract of Anisopus manni stem in alloxan-induced diabetic rats

This study examined the effect of aqueous extract of Anisopus manni stem in alloxan-induced diabetic rats. Fifteen male rats were randomly distributed into three groups of five rats each. Normal and diabetic control groups were given distilled water. Diabetic treated group, received 400 mg/kg body weight of aqueous extract of Anisopus manni. All Administrations (oral) were carried out daily for 28 days using gavage. Fasting blood glucose and body weight were recorded at intervals of 7 days. Significant (P<0.05) increases in TG, Total cholesterol, LDL-C with significant (P<0.05) decrease in HDL-C levels were observed in diabetic control compared to normal control. Significant increase was also observed in the fasting blood glucose of diabetic control rats relative to normal control. The plant extract reverses the effects of alloxan on lipid profile levels and fasting blood glucose of diabetic treated animals. The extract exerted significant (P< 0.05) reduction in fasting blood glucose level in diabetic treated rat from week one to week three compared to diabetic control. No significant (P>0.05) effect was observed in the fourth week. The findings indicate that Anisopus mannii possess hypolipidemic and antihyperglycemic potentials.Keywords: Alloxan, Anisopus manni, antihyperglycemic, lipid profile, rat

Evaluating the utilisation of Climate-Smart Agriculture (CSA) technologies and practices among smallholder farmers in The Lawra, Jirapa and Nandom districts of Ghana

Climate change is posing threat to agriculture in sub-Saharan Africa including Ghana. Climate-Smart Agriculture (CSA) is proposed to solve climate change impacts on agriculture. Smallholder farmers are adopting various strategies to be resilient to climate change effects. Empirical research is required to evaluate CSA utilisation in Ghana. Lawra, Jirapa and Nandom districts in the climate-risk areas of Guinea Savannah agro-ecological zone were chosen and Participatory Rapid Appraisal (PRA) tools were used. Farm budget analysis and market price methods were employed; key financial decision-making tools were net returns, profit margins and benefit-cost ratio. Soft systems content analysis, frequencies, means, ranking and data aggregation were employed to generate results. CSA use in the study districts was smallholder driven and male dominated. CSA was mainly used for staples including cereals and legumes and small ruminants under livestock. Crop-livestock integration and crop rotation were the common CSA practices with the highest costs (GH¢6,370.00) and highest revenues (GH¢9,460.00) respectively. Utilisation of CSA in the districts is beneficial and investments are profitable and financially viable. All actors and stakeholders must join forces to promote CSA in the districts. Rigorous promotional campaigns, capacity building and funding at all levels are crucial for CSA adoption in Ghana

Indistinguishable Particles in Quantum Mechanics: An Introduction

In this article, we discuss the identity and indistinguishability of quantum systems and the consequent need to introduce an extra postulate in Quantum Mechanics to correctly describe situations involving indistinguishable particles. This is, for electrons, the Pauli Exclusion Principle, or in general, the Symmetrization Postulate. Then, we introduce fermions and bosons and the distributions respectively describing their statistical behaviour in indistinguishable situations. Following that, we discuss the spin-statistics connection, as well as alternative statistics and experimental evidence for all these results, including the use of bunching and antibunching of particles emerging from a beam splitter as a signature for some bosonic or fermionic states.Comment: To appear in Contemp. Phy

Consistent Anisotropic Repulsions for Simple Molecules

We extract atom-atom potentials from the effective spherical potentials that suc cessfully model Hugoniot experiments on molecular fluids, e.g., $O_2$ and $N_2$. In the case of $O_2$ the resulting potentials compare very well with the atom-atom potentials used in studies of solid-state propertie s, while for $N_2$ they are considerably softer at short distances. Ground state (T=0K) and room temperatu re calculations performed with the new $N-N$ potential resolve the previous discrepancy between experimental and theoretical results.Comment: RevTeX, 5 figure

Long-term stability of angle-stable versus conventional locked intramedullary nails in distal tibia fractures

Background: In the last years intramedullary nailing has become the treatment of choice for most displaced diaphyseal tibia fractures. In contrast intramedullary nailing of distal tibia fractures is accompanied by problems like decreased biomechanical stability. Nevertheless the indications for intramedullary nailing have been extended to include even more distal fractures. The purpose of this study was to compare long-term mechanical characteristics of angle-stable versus conventional locked intramedullary nails in the treatment of unstable distal tibia fractures. Therefore, the effect of time on the mechanical properties of biodegradable sleeves was assessed. Methods: 8 pairs of fresh, frozen porcine tibiae were used. The expert tibial nail (Synthes) was equipped with either three conventional locking screws (CL) or the angle-stable locking system (AS), consisting of a special ASLS screw and a biodegradable sleeve. Biomechanical testing included torsional and axial loading at different time-points over 12 weeks. Results: The AS group showed a significantly higher torsional stiffness at all time-points (at least 60%) compared to the CL group (p 0.05). For axial stiffness and range of motion significant differences were found in the AS group. Conclusions: The angle-stable locking system (ASLS) with the biodegradable sleeve provides significantly higher long-term stability. Especially the differences determined under torsional loading in this study may have clinical relevance. The ASLS permits the potential to decrease complications like secondary loss of reduction and mal-/non-union.