Eneterotoxigenic Bacillus cereus and Bacillus thuringiensis Spores in U.S. retail Spices

Bacillus cereus is a ubiquitous organism and a potential foodborne pathogen that can cause two types of gastrointestinal diseases: emesis and diarrhea. The emetic syndrome is caused by a heat and acid stable peptide toxin that is pre-formed in food, while the diarrheal syndrome is associated to two 3-protein, heat labile enterotoxin complexes that are formed in the intestine after ingestion of the organism. There are many reports on the isolation and characterization of Bacillus cereus from various foods, however there are no studies on the levels, toxigenicity and physical characteristics of B. cereus isolated from U.S. retail spices. A huge part of spices sold in the U.S. are imported from developing nations. Developing nations lack hygienic practices during processing and packaging of spices, due to which there is a high chance of imported spices being contaminated with B. cereus. Therefore, the main objective of this thesis work was to characterize B. cereus spores from U.S. retail spices. Levels of aerobic spores and B. cereus spores were determined. B. cereus spores were further analyzed for their enterotoxigenic ability, growth characteristics and physical spore characteristics. In the 247 spice samples analyzed 77 were found to contain B. cereus, while 11 were positive for B. thuringiensis. Eighty four of the 88 spices tested possessed either one of the enterotoxin genes. None of the isolates tested positive for the emetic toxin (ces) gene. Seventy five of the B. cereus isolates grew at 12 °C, although only two isolates grew well at 9 °C. Seven selected diarrheal B. cereus spore strains had D95-values ranging from 0.64-3.53 min while the two emetic strains had D95-values of 7.04 min and 6.64 min. B. cereus grew well in pre-cooked rice. After 48 h, counts of 1.26 X 107 and 3.8 X 107 B. cereus/ 10 g were obtained in pre-cooked rice maintained at 17 °C and 20 °C respectively. At 12 °C, counts did not reach 104 CFU/ 10g even after 48 h of incubation. The aerobic mesophilic bacterial population and B. cereus population of 0.1% crushed pepper in pre-cooked rice over a period of 48h at temperature 20 °C and 17 °C were also analyzed. Counts of B. cereus in pepper rice samples reached a maximum of 1600 MPN/ 10 g and 1100 MPN/ 10 g at 20 °C and 17 °C respectively while the aerobic mesophilic counts per 10 g were 2.4 X 108 and 4.4 X 106 at these temperatures. The low B. cereus counts and high aerobic mesophilic population indicates competition of nutrients in cooked rice by background flora other than B. cereus. The physical spore characteristics of five B. cereus and 3 B. thuringiensis strains were studied using transmission electron microscopy (TEM). Tubular, whip-like appendages were present in four B. cereus and two B. thuringiensis, while all seven isolates possessed exosporia

EFFICIENT E-MRZT ALGORITHM BASED TREE CONSTRUCTION TECHNIQUE FOR ZIGBEE MOBILE WIRELESS NETWORKS

In Wireless Personal Area Networks (WPANs), the Zigbee protocol/IEEE 802.15.4 standard is a protocol specification for low range, less cost and low power systems. The Zigbee network is usually constructed using cluster trees for the purpose of performing data delivery among nodes and for power saving. Here the data delivery failures occur due to node mobility. In order to handle node movements so as to increase data delivery we use mobility-robust tree construction technique with clustering mechanism. In this paper we propose an E-MRZT (Extended MRZT) algorithm. We collect information about regularity of mobility patterns and by using this history, perform data delivery. We employ a clustering mechanism in our network to obtain a set of cluster trees; each with a specific mobility pattern. The entire setup is developed and simulated by using NS2 network simulator. The result is that we obtain mobility-robust tree with a considerable increase in data delivery

Utilisation of line surge arrestors to improve overhead HVAC and EHVDC line performance under lightning conditions.

Doctoral Degree. University of KwaZulu-Natal, Durban.In high lightning areas, lightning strokes play an important role in the performance of overhead EHV AC and DC lines. A single lightning stroke, that terminate on the earth wire and/or tower can lead to back flashovers. This flashover depends on factors such as conductor type, tower, soil resistivity and magnitude of the stroke. The flashover across the insulator and the resultant fault current surge will propagate along the line, until it is extinguished or the breaker operates. This movement of the surge currents tend to damage and reduce the life span of associated equipment such and circuits breakers, insulators, transformers and impact network performance adversely. Furthermore, this operation of the protective devices leads to power interruption to consumers on that network, and loss of production, thus negatively impacting the economy. This thesis investigates the incidences of network failure due to lightining strokes occuring on Eskom HVAC network as well as HVDC networks, considering soil resistivity, tower footing resistance and factors that influence the earthing resistances. Tower footing resistance needs to be kept uniform and as low as possible to extinguish the surge across the tower and hence reducing the back flashovers across the insulator under lightning conditions. Theoretical simulations were conducted on the different methods that are available to improve the tower footing resistance values. A case study was undertaken to ascertain the tower footing resistance of an 88kV Eskom line. The crows earthing configuration was then utilized to reduce the footing resistance to a value less than 30 ohms, using line surge arrestors (LSA) which are devices that can drain power surges to ground, if placed adequately and in sufficient numbers. Furthermore the thesis determines the relationship between the magnitude of the lightning stroke, the tower top voltage, tower footing resistance and hence the back flashover voltage that would appear on the line, which would lead to power interruptions. Surge arrestors were modelled using MATLAB software. The required number of surge arrestors per phase is thus determined that is required to drain the surge current down to earth., thus preventing power interruptions. EHV AC and DC cases studies are simulated and results are presented snd discussed.Publications listed on page iii

An immunohistochemical evaluation of the effect of salt (NaCI) on adrenal adrenomedullin content in Dahl rats.

Thesis (M.Sc.)-University of Durban-Westville, 2003.Adrenomedullin (ADM) is a 52 amino acid vasodilator peptide isolated, in 1993, from human pheochromocytoma. It has been demonstrated in the adrenal medulla of several mammalian species, including humans and rats. There have been conflicting results of the tissue distribution in the adrenal cortex. Hypertension is a complex trait with multiple genetic and environmental influences. Furthermore, salt-sensitive hypertension is characterized by a cluster of renal, hormonal, and metabolic derangements that might favour the development of cardiovascular and renal complications. Therefore the objective of this study was to investigate the adrenal distribution of ADM as well as to semi-quantitatively assess the adrenomedullin secretory capacity of the adrenal gland in the rat model of salt sensitive hypertension. Fourty-four male weanling rats were divided into 4 experimental groups and placed on a dietary regimen for 6 weeks viz. Dahl salt sensitive (DSS) rats on a high sodium diet (8% NaCl), DSS on a normal sodium diet (1% NaCl) matched with normotensive Dahl salt resistant (DSR) rats on the same dietary treatments. Blood pressure was monitored by tail-cuff readings and by the end of the six weeks, the DSS rats developed hypertension with tachycardia irrespective of the diet they were fed. The normal sodium diet was found to delay the development of hypertension, whilst the high sodium diet exacerbated the development of hypertension. Kidney weights and heart weights were greater in DSS rats than DSR rats probably due to their renal pathology or cardiac hypertrophy. Adrenomedullin immunopositivity was found predominantly in the adrenal medulla, and to varying degrees in the zona glomerulosa and zona reticularis of the adrenal cortex. The semi-quantitative analysis indicate that there was a 6.3 fold increase in ADM content of DSS rats compared to the DSR rats, where both consumed the 1% NaCI supplemented diet (DSR : 5.98 ± 0.3 vs. DSS : 37.85 ± 0.5,

Active LC Clamp dv/dt Filter for Voltage Reflection due to Long Cable in Induction Motor Drives

This paper presents an active LC clamped dv/dt filter to mitigate the over voltages appearing across the motor terminals. The over voltages at motor terminal is due to voltage reflection effect of long motor cable connected between high frequency PWM inverter having high dv/dt switching waveforms and ac motor drives. The voltage reflection due to fast switching transients can be reduced by increasing the rise time and fall time of inverter output voltage pulses. The most commonly available mitigating technique is a passive dv/dt filter between inverter and cable.  Since, size, cost and losses of passive LC dv/dt filter is more, an active dv/dt filtering technique is used to reduce over voltage at motor terminals. Active LC clamp filtering technique used here consists of a small LC filter designed for a single motor cable length which can be used for any lengths of cable up to 1000m only by changing the active control of the PWM pulses to achieve the desired voltage slope during voltage transition period. The basic principle of active dv/dt filer used here is to charge and discharge the capacitor in the filter with modified PWM pulses to increase the rise time and fall time of output voltage pulses without any extra devices to handle the transient response of the LC filter. Detailed investigation is carried out by simulation using MATLAB-Simulink software with active control of common LC clamp dv/dt filter suitable for various cable lengths ranging from 100 m to 1000 m. Comparative analysis is done with active dv/dt filter designed with a common LC clamp filter and active LC clamp dv/dt filter designed for various cable lengths and also with diode clamped passive dv/dt filter. The results proves the effectiveness of the active common LC dv/dt filter to mitigate the over voltages at motor terminal for cable lengths up to 1000m

Implementing peace education as a part of the South African school curriculum for learners in the intermediate phase (grades 4-6)

Thesis (M.A.)-University of Natal, Durban, 2003.This research article deals with the implementation of peace education in the intermediate phase of South African schools. The specific questions that this research article attempts to address are: (i) What is peace education, with particular reference to its aims and objectives? (ii) Why is it important to include peace education in any school curriculum? (iii) What is the present status of peace education in the National curriculum? (iv) What has been the experience of educators with this curriculum? (v) How may the curriculum be modified to take account of peace education principles? Chapter one provides an overview, outlining the research objectives and the structure of the research article. Chapter two attempts to review the body of literature that has been written on the subject of peace education. In an effort to accomplish this, the article firstly attempts to provide a widely accepted definition of the concept of peace education. In this regard several definitions of different researchers have been presented and discussed and finally a single definition has been formulated for the purposes of this article. Chapter two attempts to provide an analysis of the aims and objectives of peace education. The varying views by different researchers have been presented. After careful consideration of these views a set of aims and objectives have been presented for the purpose of this research article. Chapter three provides strong evidence that children who are exposed to peace education develop more positively. They perceive their social world and react to social factors in a less hostile way. Furthermore, these individuals see violence as an unacceptable option, and choose nonviolent ways to resolve conflict. Chapter four reviews the research design that has been used in data collection. This chapter also focuses on the methodology and techniques employed in the analysis of the data. Chapter five provides an analysis of the research findings. This analysis is presented in two parts. Chapter six focuses on those objectives of peace education that are of critical importance but have not been included in the National Curriculum Statement grades R-9 (schools) 1997 (NCS) or the Revised National Curriculum Statement grades R-9 (schools) 2002 (RNCS). It will be illustrated that when these objectives are incorporated in the curriculum, it will strengthen the curriculum in terms of its provision for the effective teaching of peace education. Chapter seven contains a summary of the salient discussion points of the research and concluding remarks by the researcher

Distal femoral rotational axes of knees in an elderly Indian population.

To define the angular relationships of the distal femoral rotational axes in an Indian population aged between 50 and 75 years using Magnetic Resonance Imaging (MRI) scans of the knee joint. MATERIALS AND METHODS: Institutional Review Board approved retrospective study of 300 MRI knees of patients aged between 50 and 75 years to define the Posterior Condylar Angle (PCA) and Whiteside’s Epicondylar Angle (W-EP). The results were compared with pre-existing literature to assess whether knowing these values in this age group may help in bringing about changes in the design of TKA implants for the elderly Indian population. RESULTS: Total number of knees studied was 300 (147 left and 153 right, in 144 men and 156 women). Mean age of patients was 56.7 years (SD 6.3 years), range – 50 to 75 years. The mean PCA and W-EP were 5.5º (SD, 1.2º; range, 2.2º–8.8º), 92.5º (SD, 2º; range, 90º - 99.4º), respectively. CONCLUSIONS: Differences have been noted in the distal femoral rotational axes between various races. Mean PCA and W-EP angles in the Indian population are similar to other Asian races such as the Chinese and Japanese in that they are more externally rotated but dissimilar when compared the Western population. Hence using fixed values to describe the angles between the axes can lead to femoral component malrotation. Therefore knowledge of the racial differences is important when implants for the Indian population are designed

Determination of the cause of mucoid enteritis disease in domestic rabbits

Call number: LD2668 .T4 1957 S55Master of Scienc