The assessment of posture and balance post-stroke

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Physiotherapy for people with stroke has been found to be beneficial but details of the most effective interventions are unclear. Further development of the evidence base for stroke physiotherapy is limited by a lack of clinical practice models, sensitive clinically based outcome measures and effective stratification techniques to characterise homogenous groups of subjects. These issues are addressed here with regard to balance and posture. These aspects were chosen because they form a cornerstone of stroke physiotherapy as they are thought essential for the rehabilitation of functional activities. A systematic review of assessment methods in the literature revealed a lack of measurement tools which met the utility criteria: reliability, validity, sensitivity to short-term change, suitability for a wide range of abilities, ease of use and suitability for different settings. This prompted the development of a new measurement tool. Firstly, a model of the clinical assessment process was developed using an adapted focus group method with neurological physiotherapists. This informed the content of a new measurement tool which combined an ordinal scale with functional performance tests- the Brunel Balance Assessment. The tool was evaluated in a series of studies involving 92 stroke patients. It was hierarchical (coefficient of reproducibility= 0.99, coefficient of scalability = 0.69), reliable (100% agreement) and valid as a measure of balance disability (r=0.58-0.97). The psychometric properties of the individual functional performance tests were also tested and found to be reliable (ICCs =0.88-1) and valid (r=0.32-0.63). Measurement error ranged 0-40% and the minimum change needed to detect true clinical change was calculated for each test. Balance disability, measured with the Brunel Balance Assessment, is heterogeneous with sitting, standing and stepping balance forming distinct levels of ability (p<0.027). Consequently, the BBA could be used to stratify people with stroke according to balance ability. Weakness, sensation and age were significant independent contributors to balance disability (r2=82.7%). Balance ability was a strong contributor to independence in ADL (p<0.0001). The findings of this thesis address the issues that have limited research into stroke physiotherapy with regard to balance disability. In relation to clinical practice, a robust measurement and stratification tool has been developed.Department of Health Studies, Brunel University and the Brunel University Research Enterpris

Formation of Space-Time Structure in a Forest-Fire Model

We present a general stochastic forest-fire model which shows a variety of different structures depending on the parameter values. The model contains three possible states per site (tree, burning tree, empty site) and three parameters (tree growth probability $p$, lightning probability $f$, and immunity $g$). We review analytic and computer simulation results for a quasideterministic state with spiral-shaped fire fronts, for a percolation-like phase transition and a self-organized critical state. Possible applications to excitable systems are discussed.Comment: 20 pages REVTEX, 9 figures upon reques

How to measure fatigue in neurological conditions? A systematic review of psychometric properties and clinical utility of measures used so far

Objective: To systemically review the psychometric properties and clinical utility (feasibility) of tools to measure fatigue in neurological conditions. Data sources: AMED, CINAHL, MEDLINE, Science Direct and Web of Knowledge were searched for studies of the psychometric properties of fatigue measures in adults with central nervous system disorders. Search terms were: Fatigue AND assess* OR measure* OR tool OR outcome OR index OR test OR scale AND stroke OR cerebrovascular* OR hemi* OR parkinson* OR sclerosis OR head injury OR brain injury OR motor neurone disease OR neuro* Review methods: Articles that addressed validity; reliability and ability to detect change were selected. Two authors independently selected articles and extracted data. Strength of the psychometric properties and clinical utility were assessed against predetermined thresholds. Results: A total of 25 articles were selected and 17 measurement tools identified including six versions of the Fatigue Severity Scale and five versions of the Fatigue Impact Scale. All were clinically feasible but none met all the criteria. Most were valid. Reliability and ability to detect change were infrequently evaluated, but were adequate when reported. The most thoroughly developed and psychometrically robust measures were the Neurological Fatigue Indices. Conclusion: Although many measures of fatigue in neurological conditions have published, none met all of the criteria for psychometric robustness and clinical utility but the Neurological Fatigue Indices are the best and can be used with caution </jats:sec

Experiments On Delayed Failure During Galvanizing Of Flame-Cut Structural Steels

Cracks have occasionally been found after hot-dip galvanizing of flame-cut structural beams. A project has been completed at CANMET to find the causes of this problem. Experiments have been designed to measure the time-to-failure of notched samples under near-constant load. Cracking during galvanizing is caused by liquid-metal embrittlement, and occurs for critical combinations of stress and susceptible material. Sources of stress are residual stresses including those from flame cutting, and thermal stresses from thermal gradients during hot dipping. Material susceptibility is related primarily to surface hardness, and correlates well with micro-hardness measured at 100 micrometres depth. Remedial measures to eliminate cracking require either reduction of the hardness below a critical level (270 Vickers), or reduction of residual and thermal stresses

Cosmology with Weak Lensing Surveys

Weak gravitational lensing surveys measure the distortion of the image of distant sources due to the deflections of light rays by the fluctuations of the gravitational potential along the line of sight. Since they probe the non-linear matter power spectrum itself at medium redshift such surveys are complimentary to both galaxy surveys (which follow stellar light) and cosmic microwave background observations (which probe the linear regime at high redshift). Ongoing CMB experiments such as WMAP and the future Planck satellite mission will measure the standard cosmological parameters with unprecedented accuracy. The focus of attention will then shift to understanding the nature of dark matter and vacuum energy: several recent studies suggest that lensing is the best method for constraining the dark energy equation of state. During the next 5 year period ongoing and future weak lensing surveys such as the Joint Dark Energy Mission (JDEM, e.g. SNAP) or the Large-aperture Synoptic Survey Telescope (LSST) will play a major role in advancing our understanding of the universe in this direction. In this review article we describe various aspects of weak lensing surveys and how they can help us in understanding our universe.Comment: 15 pages, review article to appear in 2005 Triennial Issue of Phil. Trans.

Fluorescent aromatic sensors and their methods of use

Aromatic molecules that can be used as sensors are described. The aromatic sensors include a polycyclic aromatic hydrocarbon core with a five-membered imide rings fused to the core and at least two pendant aryl groups. The aromatic sensor molecules can detect target analytes or molecular strain as a result of changes in their fluorescence, in many cases with on-off behavior. Aromatic molecules that fluoresce at various frequencies can be prepared by altering the structure of the aromatic core or the substituents attached to it. The aromatic molecules can be used as sensors for various applications such as, for example, the detection of dangerous chemicals, biomedical diagnosis, and the detection of damage or strain in composite materials. Methods of preparing aromatic sensor molecules are also described