Liberato Camilleri

Dual Adaptive Dynamic Control of Mobile Robots Using Neural Networks

This paper proposes two novel dual adaptive neural control schemes for the dynamic control of nonholonomic mobile robots. The two schemes are developed in discrete time, and the robots nonlinear dynamic functions are assumed to be unknown. Gaussian radial basis function and sigmoidal multilayer perceptron neural networks are used for function approximation. In each scheme, the unknown network parameters are estimated stochastically in real time, and no preliminary offline neural network training is used. In contrast to other adaptive techniques hitherto proposed in the literature on mobile robots, the dual control laws presented in this paper do not rely on the heuristic certainty equivalence property but account for the uncertainty in the estimates. This results in a major improvement in tracking performance, despite the plant uncertainty and unmodeled dynamics. Monte Carlo simulation and statistical hypothesis testing are used to illustrate the effectiveness of the two proposed stochastic controllers as applied to the trajectory-tracking problem of a differentially driven wheeled mobile robot.

Gram Negative Wound Infection in Hospitalised Adult Burn Patients-Systematic Review and Metanalysis-

Background Gram negative infection is a major determinant of morbidity and survival. Traditional teaching suggests that burn wound infections in different centres are caused by differing sets of causative organisms. This study established whether Gram-negative burn wound isolates associated to clinical wound infection differ between burn centres. Methods Studies investigating adult hospitalised patients (2000–2010) were critically appraised and qualified to a levels of evidence hierarchy. The contribution of bacterial pathogen type, and burn centre to the variance in standardised incidence of Gram-negative burn wound infection was analysed using two-way analysis of variance. Primary Findings Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumanni, Enterobacter spp., Proteus spp. and Escherichia coli emerged as the commonest Gram-negative burn wound pathogens. Individual pathogens’ incidence did not differ significantly between burn centres (F (4, 20) = 1.1, p = 0.3797; r2 = 9.84). Interpretation Gram-negative infections predominate in burn surgery. This study is the first to establish that burn wound infections do not differ significantly between burn centres. It is the first study to report the pathogens responsible for the majority of Gram-negative infections in these patients. Whilst burn wound infection is not exclusive to these bacteria, it is hoped that reporting the presence of this group of common Gram-negative “target organisms” facilitate clinical practice and target research towards a defined clinical demand.

Attitudes towards and Effects of the Use of Video Games in Classroom Learning with Specific Reference to Literacy Attainment

The first part of this study shows that there is increased support for using video games in the classroom from different stakeholders, namely students, teachers and parents. The potential role that video games can play in the classroom learning process needs to be more well defined. There is a dire need for research work under experimental conditions which measures tangibly the effectiveness of videogame use in classroom learning. The experimental study described here seeks to address this need and focuses on the very important area of literacy attainment. The Experimental Group of students which used the videogame in the classroom obtained significant gains on a number of English as a Second Language items when compared to the other group of students which followed their regular programme. This study makes a claim for teachers to be supported in their endeavours to harness video games as a teaching and learning tool. However, the role of teachers in this process requires redefinition. It calls also for the concerns of teachers to be addressed if they are to feel they can play a significant role in the adoption of video games in classroom learning.

External rib structure can be predicted using mathematical models: An anatomical study with application to understanding fractures and intercostal muscle function.

As ribs adapt to stress like all bones, and the chest behaves as a pressure vessel, the effect of stress on the ribs can be determined by measuring rib height and thickness. Rib height and thickness (depth) were measured using CT scans of seven rib cages from anonymized cadavers. A Finite Element Analysis (FEA) model of a rib cage was constructed using a validated approach and used to calculate intramuscular forces as the vectors of both circumferential and axial chest wall forces at right angles to the ribs. Nonlinear quadratic models were used to relate rib height and rib thickness to rib level, and intercostal muscle force to vector stress. Intercostal muscle force was also related to vector stress using Pearson correlation. For comparison, rib height and thickness were measured on CT scans of children. Rib height increased with rib level, increasing by 13% between the 3rd and 7th rib levels, where the 7th/8th rib was the widest part or “equator” of the rib cage, P < 0.001 (t‐test). Rib thickness showed a statistically significant 23% increase between the 3rd and 7th ribs, P = 0.004 (t‐test). Intercostal muscle force was significantly related to vector stress, Pearson correlation r = 0.944, P = 0.005. The three nonlinear quadratic models developed all had statistically significant parameter estimates with P < 0.03. External rib morphology, in particular rib height and thickness, can be predicted using statistical mathematical models. Rib height is significantly related to the calculated intercostal muscle force, showing that environmental factors affect external rib morphology. Clin. Anat. 28:512–519, 2015.

Statistical characterization of succinoylated dextrin degradation behavior in human α-amylase

Dextrin is a biomedically well-established, water-soluble polymer that has recently attracted considerable interest for conjugation to bioactive payloads. Succinoylation functionalizes dextrin and alters the rate at which it is degraded by human amylase, providing the bases for a convenient, controlled drug release technology. To date, the choice of a succinoylated dextrin intermediate requires laborious physicochemical characterization of entire libraries of succinoylated dextrin intermediates. We report the governance of dextrin degradation as a function of initial polymer molecular weight and degree of succinoylation through statistical analysis of a library of succinoylated dextrins relevant to acute disease (parent-dextrin molecular weight: 8,100 to 28,900 g/mol; 0 to 14.5 mol% succinoylation) at a typical physiologic concentration of human amylase (100 IU/L). Within these parameters, the rate of degradation of all succinoylated dextrins was best predicted by logarithmic regression. The contribution of degree of succinoylation to the variance in the degradation rate increased progressively and substantially with decreasing initial polymer weight (4.19% to 21.33%). These results facilitate the choice of succinoylated dextrin intermediates in the construction of controlled-release constructs, increase relevance to clinical scenarios requiring specific controlled-release rates, and contribute to the adoption of succinoylated dextrin as a versatile polymer for conjugation in controlled-release therapeutics.

A Healthy Start: Promoting Mental Health and Well-Being in the Early Primary School Years.

Mental health problems in children represent a significant international health concern, with up to one in five children using mental health services during the course of any given year. Identifying the processes of what prevents social, emotional and behaviour difficulties (SEBD) and promotes healthy development from an early age can make a significant contribution to the promotion of positive mental health in children. This article describes a longitudinal study which sought to identify the risk and promotive factors as young children move from the early to junior years in primary school. Multilevel analysis was used to identify the individual, classroom, school, home and community factors that predict change in SEBD and in prosocial behaviour in the early school years. It also calculated the cumulative effect of the various risk and promotive factors on the pupils’ well-being and mental health. The article presents the windows of vulnerability and opportunity for young children’s healthy development, proposing a trajectory for healthy development in early and middle childhood.

Establishing Differences in Thermographic Patterns between the Various Complications in Diabetic Foot Disease

Aim To evaluate the potential of thermography as an assessment tool for the detection of foot complications by understanding the variations in temperature that occur in type 2 diabetes mellitus (DM). Methods Participants were categorized according to a medical examination, ankle brachial index, doppler waveform analysis, and 10-gram monofilament testing into five groups: healthy adult, DM with no complications, DM with peripheral neuropathy, DM with neuroischaemia, and DM with peripheral arterial disease (PAD) groups. Thermographic imaging of the toes and forefeet was performed. Results 43 neuroischaemic feet, 41 neuropathic feet, 58 PAD feet, 21 DM feet without complications, and 126 healthy feet were analyzed. The temperatures of the feet and toes were significantly higher in the complications group when compared to the healthy adult and DM healthy groups. The higher the temperatures of the foot in DM, the higher the probability that it is affected by neuropathy, neuroischaemia, or PAD. Conclusions Significant differences in mean temperatures exist between participants who were healthy and those with DM with no known complications when compared to participants with neuroischaemia, neuropathy, or PAD. As foot temperature rises, so does the probability of the presence of complications of neuropathy, neuroischaemia, or peripheral arterial disease.

A hypothesis for reactivation of pulmonary tuberculosis: How thoracic wall shape affects the epidemiology of tuberculosis.

This study was aimed at determining the cause for the high incidence of tuberculosis (TB) reactivation occurring in males with a low body mass index (BMI). Current thinking about pulmonary TB describes infection in the lung apex resulting in cavitation after reactivation. A different hypothesis is put forward for TB infection, suggesting that this occurs in subclinical apical cavities caused by increased pleural stress due to a low BMI body habitus. A finite element analysis (FEA) model of a lung was constructed including indentations for the first rib guided by paramedian sagittal CT reconstructions, and simulations were conducted with varying antero‐posterior (AP) diameters to mimic chests with a different thoracic index (ratio of AP to the transverse chest diameters). A Pubmed search was conducted about gender and thoracic index, and the effects of BMI on TB. FEA modeling revealed a tenfold increase in stress levels at the lung apex in low BMI chests, and a four‐fold increase with a low thoracic index, r2 = 0.9748 P < 0.001. Low thoracic index was related to BMI, P = 0.001. The mean thoracic index was statistically significantly lower in males, P = 0.001, and increased with age in both genders. This article is the first to suggest a possible mechanism linking pulmonary TB reactivation to low BMI due to the flattened thoracic wall shape of young male adults. The low thoracic index in young males may promote TB reactivation due to tissue destruction in the lung apex from high pleural stress levels. Clin. Anat. 28:614–620, 2015.

Development of a Maltese version of oral health-associated questionnaires: OHIP-14, GOHAI, and the Denture Satisfaction Questionnaire.

PURPOSE To show the reliability of the Maltese translations of OHIP-14, GOHAI, and the Denture Satisfaction Questionnaire, define the reliability of the responses, and determine the correlation between OHIP-14 and GOHAI. MATERIALS AND METHODS The items of the three questionnaires (OHIP-14, GOHAI, and Denture Satisfaction) were translated into Maltese and back into English to compare with the original version. Specific sampling of a population well versed in Maltese and English was carried out to obtain a sample of respondents for each questionnaire. Data were gathered through self-administered questionnaires: first administering the Maltese version and following with the English version 1 week later. RESULTS Participation rates were high (98%). Cronbachs alpha for all three questionnaires was high (> 0.7), indicating satisfactory test-retest reliability of the instruments. Similarly, the Spearman correlation coefficients for both the English and Maltese versions of OHIP-14 and GOHAI were good (> 0.6). CONCLUSION The Maltese versions of OHIP-14, GOHAI, and the Denture Satisfaction Questionnaire can be safely used as a valid alternative to the English versions in studies of patients who are limited in linguistic proficiency.

Red blood cell distribution width and myocardial scar burden in coronary artery disease

Introduction Red blood cell distribution width (RDW) is a novel independent marker of cardiovascular disease including heart failure, coronary artery disease and myocardial ischaemia. The aim of the study was to investigate a possible relationship between RDW and myocardial scar burden, as assessed by a MIBI viability scan. A secondary objective was to assess whether there is an association between RDW and left ventricular ejection fraction (LVEF). Methods The study comprised 123 subjects with ischaemic heart disease who underwent a myocardial viability scan between June 2008 and July 2014. Haemoglobin, mean corpuscular volume, RDW, platelet count, mean platelet volume (MPV), estimated glomerular filtration rate, fasting blood glucose, liver and lipid profiles were evaluated for all patients. The extent of myocardial scarring and LVEF were noted. Data were analysed using IBM SPSS Statistics 22.0. Univariate followed by multivariate analyses were performed to assess for independent predictors of myocardial scarring and LVEF, respectively. Results The mean age of the study population was 63.5 years; most of the subjects were men. The median LVEF was 31% and median percentage of myocardial scarring was 8.7%. Multivariate analyses revealed that RDW, HDL-cholesterol and alanine transaminase were independent predictors of myocardial scarring while RDW, MPV, LDL-cholesterol and gamma-glutamyl transpeptidase were independent predictors of LVEF. Conclusions Increased RDW is an independent predictor both of myocardial scar burden and of impaired left ventricular function in subjects with coronary artery disease.