Multilevel Particle Filters for L\'evy-driven stochastic differential equations

We develop algorithms for computing expectations of the laws of models associated to stochastic differential equations (SDEs) driven by pure L\'evy processes. We consider filtering such processes and well as pricing of path dependent options. We propose a multilevel particle filter (MLPF) to address the computational issues involved in solving these continuum problems. We show via numerical simulations and theoretical results that under suitable assumptions of the discretization of the underlying driving L\'evy proccess, our proposed method achieves optimal convergence rates. The cost to obtain MSE $O(\epsilon^2)$ scales like $O(\epsilon^{-2})$ for our method, as compared with the standard particle filter $O(\epsilon^{-3})$

Biopolymer Drill-in Fluid Performance for Different Rheological Models using Statistical Characterisation

Appropriate selection of rheological models is important for hydraulic calculations of pressure loss prediction and hole cleaning efficiency of drilling fluids. Power law, Bingham-Plastic and Herschel-Bulkley models are the conventional fluid models used in the oilfield. However, there are other models that have been proposed in literature which are under/or not utilized in the petroleum industry. The primary objective of this paper is to recommend a rheological model that best-fits the rheological behaviour of xanthan gum-based biopolymer drill-in fluids for hydraulic evaluations. Ten rheological models were evaluated in this study. These rheological models have been posed deterministically and due to the unrealistic nature have been replaced by statistical models, by adding an error (disturbance) term and making suitable assumptions about them. Rheological model parameters were estimated by least-square regression method. Models like Sisko and modified Sisko which are not conventional models in oil industry gave a good fit. Modified Sisko model which is a four parameter rheological model was selected as the best-fit model since it produced the least residual mean square of 0.61 Ibf2/100ft4. There is 95% certainty that the true best-fit curve lies within the confidence band of this function of interest. Keywords: Biopolymer; Least-Square Regression; Residual Mean Squares; Rheologra

Generation of Synthetic Density Log Response using Multivariate Adaptive Regression Splines

There are instances in well logging operations where log response can be missing or inaccurate for a specific depth of interest due to wellbore conditions such as wellbore size, wellbore rugosity and mud cake effects. The conventional approach is to rerun the logs at definite depths, however, this remedial technique is costly, time-consuming and prone to errors due to the presence of a casing. Machine learning methods are currently implemented as an innovative way of predicting missing log responses. The present study seeks to investigate the potential of multivariate adaptive regression splines (MARS) as a density log predictive model. The performance of the developed MARS model was judged with the widely used artificial neural networks (ANN). The results reveal that MARS generalise better when predicting the density log response of the testing data. The MARS density log model achieved the highest correlation of 0.869, an error rate of 0.01196 and 0.1094 for MSE and RMSE respectively on the withheld dataset. While back propagation neural network (BPNN) and radial basis function neural network (RBFNN) had 0.855 and 0.802 as R, 0.0128 and 0.0147 as MSE, 0.1131 and 0.1212 as RMSE respectively. Therefore, a cost-effective MARS model can accurately generate synthetic density well log response

In search of the better? The representations of Utopia and dystopia in Kofi Awoonor’s This Earth, My Brother…

This paper is informed by the extensive corpus of African postcolonial critique that examines the after-effects of empire in ex-colonial societies. Thus, in the studied engagement of the Ghanaian ex-colonial state, this paper turns to Awoonor’s This Earth, My Brother..., read as one of such commentaries on the rusted, conscienceless ex-colonial nation and the tones of negative burdens laid on citizens’ existential quest for selfhood, self-actualisation and the assertion of identity. In such a circumstance, one may be lost between the real world and a wishful world; the real being the present state of affairs and the wishful being that for which they yearn. Through critical reading and analysis, we discuss the representations of utopia and dystopia in This Earth, My Brother..., in the light of the myriad features that these concepts offer. The paper argues that the extradiegetic Ghanaian nation has much to learn from Awoonor’s diegetic lifeworld

Monitoring quality of care in the WHO Africa Region-a study design for measurement and tracking, towards UHC attainment

This paper reports on the design of a study to generate a quality of care index for countries in the World Health Organization Africa Region.Quality of care, for all people at all times, remains pivotal to the advancement of the 2030 agenda and the attainment of Universal Health Coverage. We present a study protocol for deriving a quality of care index, hinged on indicators and data elements currently monitored through routine information systems and institutionalized facility assessments in the World Health Organization Africa Region.This paper seeks to offer more insight into options in the Region for strengthening monitoring processes of quality of care, as a step towards generating empirical evidence which can galvanize action towards an improved care process.The methodology proposed in this study design has broad implications for policymaking and priority setting for countries, emphasizing the need for robust empirical measures to understand the functionality of health systems for the delivery of quality essential services. Application of this protocol will guide policymaking, as countries work to increasingly improve quality of care and adopt policies that will best facilitate their advancement towards Universal Health Coverage

Osteomyelitis of the frontal bone

Osteomyelitis of the skull is a rare clinical presentation. It usually occurs as a complication of trauma or sinusitis. Its complications can be lifethreatening though the initial symptoms and signs are subtle. Early diagnosis and appropriate management to prevent CNS complications reduce morbidity and mortality significantly. Intracranial complications of sinusitis, focal infections and meningitis remain a great challenge. Mortality from complications is 20-40%. The prevalence of skull osteomyelitis is about 1.5% of all osteomyelitis

The Use of Bauxite as an Arsenic Filter

AbstractArsenic (As) has the potential to negatively affect soils and groundwater quality, and cause several public health challenges. It is usually concentrated and released during metal mining of ores that contains arsenic-bearing minerals. Remediation strategies are in place to avoid pollution. In this study, bauxite from Awaso, Ghana, was characterised, and its ability to sequester As was tested under varying conditions of temperature, Eh and pH. The study showed that the best particle size in the range utilised was 80% passing 2 mm as it allowed easy percolation, and As removal was about 95%. The reaction is a favourable pseudo-second order reaction that is spontaneous and thermodynamically stable and compares well with the Langmuir Sorption Isotherm. About 80% sorption was achieved within 20 minutes of contact with low desorption rate of less than 1.8%. The study thus concludes that bauxite is a good filter for arsenic. Keywords: Arsenic, Bauxite, Filter, Sorption, Isother

Current perspectives on the role of interleukin-1 signalling in the pathogenesis of asthma and COPD

Asthma and chronic obstructive pulmonary disease (COPD) cause significant morbidity and mortality worldwide. In the context of disease pathogenesis, both asthma and COPD involve chronic inflammation of the lung and are characterised by the abnormal release of inflammatory cytokines, dysregulated immune cell activity and remodelling of the airways. To date, current treatments still only manage symptoms and do not reverse the primary disease processes. In recent work, interleukin (IL)-1α and IL-1β have been suggested to play important roles in both asthma and COPD. In this review, we summarise overwhelming pre-clinical evidence for dysregulated signalling of IL-1α and IL-1β contributing to disease pathogenesis and discuss the paradox of IL-1 therapeutic studies in asthma and COPD. This is particularly important given recent completed and ongoing clinical trials with IL-1 biologics that have had varying degrees of failure and success as therapeutics for disease modification in asthma and COPD

Technical efficiency of public district hospitals and health centres in Ghana: a pilot study

BACKGROUND: The Government of Ghana has been implementing various health sector reforms (e.g. user fees in public health facilities, decentralization, sector-wide approaches to donor coordination) in a bid to improve efficiency in health care. However, to date, except for the pilot study reported in this paper, no attempt has been made to make an estimate of the efficiency of hospitals and/or health centres in Ghana. The objectives of this study, based on data collected in 2000, were: (i) to estimate the relative technical efficiency (TE) and scale efficiency (SE) of a sample of public hospitals and health centres in Ghana; and (ii) to demonstrate policy implications for health sector policy-makers. METHODS: The Data Envelopment Analysis (DEA) approach was used to estimate the efficiency of 17 district hospitals and 17 health centres. This was an exploratory study. RESULTS: Eight (47%) hospitals were technically inefficient, with an average TE score of 61% and a standard deviation (STD) of 12%. Ten (59%) hospitals were scale inefficient, manifesting an average SE of 81% (STD = 25%). Out of the 17 health centres, 3 (18%) were technically inefficient, with a mean TE score of 49% (STD = 27%). Eight health centres (47%) were scale inefficient, with an average SE score of 84% (STD = 16%). CONCLUSION: This pilot study demonstrated to policy-makers the versatility of DEA in measuring inefficiencies among individual facilities and inputs. There is a need for the Planning and Budgeting Unit of the Ghana Health Services to continually monitor the productivity growth, allocative efficiency and technical efficiency of all its health facilities (hospitals and health centres) in the course of the implementation of health sector reforms

Simultaneous bilateral or unilateral carpal tunnel release? A prospective cohort study of early outcomes and limitations

BACKGROUND: Over 60% of patients with carpal tunnel syndrome present with symptoms and findings of nerve compression in both hands. Our goal was to compare patient-rated difficulties in performing activities of daily living in the early postoperative period between those undergoing bilateral carpal tunnel release and those undergoing unilateral carpal tunnel release. METHODS: This prospective cohort study enrolled consecutive patients with bilateral carpal tunnel syndrome undergoing bilateral carpal tunnel release (n = 47) or unilateral carpal tunnel release (n = 41). Patient function and disease severity were measured by an abbreviated form of the Disabilities of the Arm, Shoulder and Hand questionnaire, QuickDASH, and the Boston Carpal Tunnel Questionnaire at baseline, at postoperative visit 1 at a mean time (and standard deviation) of 10 ± 3 days, and at postoperative visit 2 at a mean time (and standard deviation) of 30 ± 6 days. Patients rated their difficulty in completing fifteen activities of daily living each day for the first postoperative week. Patients reported the factors that influenced their choice of surgery. RESULTS: There was no difference in baseline function or disease severity between the two groups with regard to QuickDASH and the Boston Carpal Tunnel Questionnaire. Patients in both groups improved after carpal tunnel release with no difference between groups either at postoperative visit 1 for QuickDASH (p = 0.97) and the Boston Carpal Tunnel Questionnaire (p = 0.86) or at postoperative visit 2 for QuickDASH (p = 0.43) and the Boston Carpal Tunnel Questionnaire (p = 0.34). Patients undergoing bilateral carpal tunnel release had more difficulty only during postoperative days 1 to 2 in opening jars (p = 0.03), cooking (p = 0.008), and doing household chores (p = 0.02). Patients in the two groups did not differ (p > 0.05) in their abilities to perform activities of daily living necessary for personal hygiene or independence on any day during the first seven days following surgery with regard to using the bathroom, bathing, dressing, or eating. Although the most common reason why patients chose bilateral carpal tunnel release was to avoid two surgical procedures (42%), the most common reason why patients chose unilateral carpal tunnel release was concern for self-care (36%). CONCLUSIONS: Patients with bilateral carpal tunnel syndrome can anticipate more severe functional impairment during the first few postoperative days with bilateral carpal tunnel release compared with unilateral carpal tunnel release, but limitations beyond postoperative day 2 or 3 are similar for bilateral and unilateral carpal tunnel release. LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence