Design And Development of A Powered Pediatric Lower-limb Orthosis

Gait impairments from disorders such as cerebral palsy are important to address early in life. A powered lower-limb orthosis can offer therapists a rehabilitation option using robot-assisted gait training. Although there are many devices already available for the adult population, there are few powered orthoses for the pediatric population. The aim of this dissertation is to embark on the first stages of development of a powered lower-limb orthosis for gait rehabilitation and assistance of children ages 6 to 11 years with walking impairments from cerebral palsy. This dissertation presents the design requirements of the orthosis, the design and fabrication of the joint actuators, and the design and manufacturing of a provisional version of the pediatric orthosis. Preliminary results demonstrate the capabilities of the joint actuators, confirm gait tracking capabilities of the actuators in the provisional orthosis, and evaluate a standing balance control strategy on the under-actuated provisional orthosis in simulation and experiment. In addition, this dissertation presents the design methodology for an anthropometrically parametrized orthosis, the fabrication of the prototype powered orthosis using this design methodology, and experimental application of orthosis hardware in providing walking assistance with a healthy adult. The presented results suggest the developed orthosis hardware is satisfactorily capable of operation and functional with a human subject. The first stages of development in this dissertation show encouraging results and will act as a foundation for further iv development of the device for rehabilitation and assistance of children with walking impairments

Gravity model improvement using GEOS-3 (GEM 9 and 10)

The use of collocation permitted GEM 9 to be a larger field than previous derived satellite models, GEM 9 having harmonics complete to 20 x 20 with selected higher degree terms. The satellite data set has approximately 840,000 observations, of which 200,000 are laser ranges taken on 9 satellites equipped with retroreflectors. GEM 10 is complete to 22 x 22 with selected higher degree terms out to degree and order 30 amounting to a total of 592 coefficients. Comparisons with surface gravity and altimeter data indicate a substantial improvement in GEM 9 over previous satellite solutions; GEM 9 is in even closer agreement with surface data than the previously published GEM 6 solution which contained surface gravity. In particular the free air gravity anomalies calculated from GEM 9 and a surface gravity solution are in excellent agreement for the high degree terms

Effects of different combinations of Hoagland’s solution and Azolla filiculoides on photosynthesis and chlorophyll content in Beta vulgaris subsp. Cycla ‘fordhook giant’ grown in hydroponic cultures

The assessments of photosynthetic rate, stomatal conductance,  evapotranspiration, intercellular CO2 concentration and chlorophyll content in Beta vulgaris subsp. cycla ‘Fordhook Giant’ grown in hydroponic cultures containing different compositions of hydroponic solutions were evaluated in this study. The aim of the study was to quantify the effects of different combinations of Hoagland’s solution and Azolla filiculoides on photosynthesis processes and chlorophyll content in B. vulgaris grown in hydroponic cultures. The following treatments were evaluated in four replications: (1) Control (Hoagland’s solution minus N solution excluding Azolla; (2) Hoagland’s minus N solution including Azolla; (3) full Hoagland’s solution plus Azolla; and (4) full Hoagland’s solution excluding Azolla. Results show that photosynthetic rate, evapotranspiration, intercellular CO2 concentration and chlorophyll were generally higher in full Hoagland’s solution. This was closely followed by full Hoagland’s solution plus Azolla, and Hoagland’s minus N solution plus Azolla treatments. The lowest photosynthetic rates and chlorophyll contents were found in the control (Hoagland’s minus N solution) treatment.Keywords: Photosynthetic rate, stomatal conductance, evapotranspiration, intercellular CO2 concentration, chlorophyll a, chlorophyll bAfrican Journal of Biotechnology Vol. 12(16), pp. 2006-201

Effect of constitutive modeling during finite element analysis of machining-induced residual stresses in Ti6Al4V

Residual stress is an important surface integrity descriptor that may have a marked effect on the functional performance of machined alloy parts. This paper describes a finite element evaluation of the effect of different constitutive models on machining induced residual stresses for Ti6Al4V titanium alloy. A two dimensional orthogonal turning process is modelled and the results compared to experimental data. Residual stress is evaluated with respect to different elastic-viscoplastic constitutive models at certain cutting speeds and feeds. The general-purpose finite element code MSC Marc@ was used with comparisons with experimental data made relative to residual stress, cutting force and temperature. The magnitude and extent (depth) of the residual stress field is evaluated with regards to the different material models and compared with experimental data

Substance misuse in youth admitted to a psychiatric emergency unit

Objectives. To investigate the pattern of substance misuse in youth admitted to a psychiatric emergency unit of a 'major hospital, and to compare regular users of cannabis,methaqualone and alcohol with the rest of the sample in terms of selected psychosocial variables.Study population. Consecutive patients aged 25 years or younger admitted to a psychiatric emergency unit over a 3month period.Method. Patients completed a standardised questionnaire .containing questions about their family, social, economic and educational backgrounds. Their current psychiatric folder was examined to ascertain mental state and behaviour on admission as well as previous psychiatric contacts and hospitalisation. Particular attention was paid to the use of cannabis, methaqualone and alcohol For each substance patients were divided into two groups, namely those who did not use the substance or who used it infrequently, and regular users. Unadjusted odds ratios were used to document the relationship between substance use and the selected psychosocial variablesResults. One hundred and fourteen patients were assessed, of which number 61 (53.5%) were male and 98 (86%) were single. The group consisted of 37 blacks (32.5%), 56 coloureds (49.1%) and 21 whites (18.4%)_ Alcohol was . regularly used by 30 patients (263%), cannabis by 29 (25.4%), methaqualone by 11 (9.6%), and any-of these substances by 46 patients (40.4%). Unadjusted odds ratios showed that there was a significant association between regular use of alcohol and cannabis and male gender, dropping out of school, previous psychiatric treatment, and an absence of both depression and suicidal ideation; and between regular cannabis use and bizarre behaviour, auditory hallucinations and disorganised or incoherent speech. Methaqualone use was associated with hostile threats.Conclusions. In the study population substance use was associated with various adverse psychosocial circumstances; these may alert the practitioner to the possibility of substance use. Cannabis misuse was suggested by behavioural, perceptual and speech abnormalities on mental state examination

Effects of acute pre-treatment with ethanolamine on isoprenalineinduced myocardial infarction in adult Wistar rats

Ethanolamine (Etn), a biogenic amine, protects isolated hearts against MI, but its effects in vivo are unknown. In this study, we investigated the effects of Etn pretreatment on isoprenaline (ISO)-induced MI in vivo. Wistar rats were treated with either Etn (10mg.kg-1, i.p.) or saline, prior to either ISO (67mg.kg-1, s.c.) or saline. Haemodynamic- and electrocardiographic parameters were recorded under anaesthesia, 24 hours post-treatment with ISO. Infarct sizes were determined by triphenyltetrazolium chloride staining. Oxidative stress plasma parameters, conjugated dienes (CD) and thio-barbituric acid reactive substances (TBARS), were measured by spectrophotometric analysis. Etn decreased ISO-induced pathological Q-waves, but had no effect on ISO-induced low-voltage electrocardiogram. In addition, Etn decreased overall mortality induced by ISO treatment. However, Etn did not prevent ISO-induced infarction or the systolic- and diastolic hypotensive effects. Etn also enhanced the ISO-induced increase in heart-to-body weight ratio, and reversed the decrease in lungs-to-body weight ratio. Neither ISO nor Etn altered CD or TBARS. These results suggest that, despite a tendency to modulate cardiac electrical activity, Etn did not prevent ISO-induced MI or myocardial dysfunction in vivo

Distortional Buckling of Cold-formed Stainless Steel Compression Members

In this paper the critical local buckling strength of cold-formed stainless steel compression members, with special emphasis on the method developed by Lau and Hancock for distortional buckling is discussed. Cold-formed stainless steel channel and I-section members under axial compression in distortional buckling are analysed. A control experiment is carried out for comparing analytical methods with a finite element method and experimental values

Effects of pH and Phosphorus Concentrations on the Chlorophyll Responses of Salvia chamelaeagnea (Lamiaceae) Grown in Hydroponics

Salvia chamelaeagnea (Lamiaceae) is a slow growing water‐wise evergreen shrub originating from the western province of South Africa. It is an attractive landscape, and S. chamelaeagnea is a medicinal plant. It is important to develop enhanced cultivation protocols that could result in high yield and high‐quality medicinal materials. Chlorophyll is a fundamental part of the light‐dependent reactions of the photosynthesis process. This chapter investigates the effects of four phosphorus concentrations and three pH levels of supplied irrigated water on the production of chlorophyll A, chlorophyll B, total chlorophyll, leaf colour and the nutrient uptake of S. chamelaeagnea grown in hydroponics over an 8‐week period at the Cape Peninsula University of Technology. The treatments of pH 4, pH 6 and pH 8 at 31, 90, 150 and 210 ppm of phosphorus were received by 12 groups of plants and were replicated 10 times. The results indicated that at pH 4, P fertilization significantly (P < 0.05) induced a higher chlorophyll production of S. chamelaeagnea grown in hydroponics compared to other pH treatments (pH 8 and pH 6)

Changes in Vitamin A and C Levels In Black Mine-Workers

An investigation of the vitamin A and C status of Black mine-workers was carried out at the request of the Anglo American Corporation of South Africa Ltd. It was found that, although there was no evidence of widespread vitamin A deficiency, there was sufficient evidence of subclinical deficiency to warrant further investigation. In spite of apparently adequate vitamin C intakes, a relatively high incidence of subclinical vitamin C deficiency was found. It is strongly recommended that further studies be undertaken to establish what are the minimum levels of vitamin A and C required daily to reduce effectively the incidence of subclinical deficiency

Tracking mortality in near to real time provides essential information about the impact of the COVID-19 pandemic in South Africa in 2020

Background. Producing timely and accurate estimates of the impact of COVID-19 on mortality is challenging for most countries, but impossible for South Africa (SA) from cause-of-death statistics. Objectives. To quantify the excess deaths and likely magnitude of COVID-19 in SA in 2020 and draw conclusions on monitoring the epidemic in 2021. Methods. Basic details of deaths registered on the National Population Register by the Department of Home Affairs (DoHA) are provided to the South African Medical Research Council weekly. Adjustments are made to the numbers of weekly deaths to account for non-registration on the population register, as well as late registration of death with the DoHA. The weekly number of deaths is compared with the number predicted based on the Holt-Winters time-series analysis of past deaths for provinces and metropolitan areas. Excess deaths were calculated for all-causes deaths and natural deaths, using the predicted deaths as a baseline. In addition, an adjustment was made to the baseline for natural deaths to account for the drop in natural deaths due to lockdown. Results. We estimated that just over 550 000 deaths occurred among persons aged ≥1 year during 2020, 13% higher than the 485 000 predicted before the pandemic. A pronounced increase in weekly deaths from natural causes peaked in the middle of July across all ages except &lt;20 years, and across all provinces with slightly different timing. During December, it became clear that SA was experiencing a second wave of COVID-19 that would exceed the death toll of the first wave. In 2020, there were 70 000 - 76 000 excess deaths from natural causes, depending on the base. Using the adjusted base, the excess death rate from natural causes was 122 per 100 000 population, with a male-to-female ratio of 0.78. Deaths from unnatural causes halved for both males and females during the stringent lockdown level 5. The numbers reverted towards the predicted number with some fluctuations as lockdown restrictions varied. Just under 5 000 unnatural deaths were averted. Conclusions. Tracking the weekly numbers of deaths in near to real time has provided important information about the spatiotemporal impact of the pandemic and highlights that the ~28 000 reported COVID-19 deaths during 2020 substantially understate the death toll from COVID-19. There is an urgent need to re-engineer the system of collecting and processing cause-of-death information so that it can be accessed in a timely way to inform public health actions