Electrospinning process is a simple and widely used method for producing polymeric nanofibres. However, despite its popularity, significant challenges remain in controlling the fibre deposition due to the complex nature of electrospinning process. The process is renowned for its chaotic motion of fibre deposition, also known as the whipping instability. This instability is caused by electrostatic and fluid dynamics interactions of the charged jet and it is partly responsible for the thinning of the fibres into nanoscale diameters. Due to the instability, an electrospinning process typically deposits random orientated fibres in a circular deposition area. Furthermore, there is no control over the location where the fibres land on the collector electrode except that the fibres always travel through the shortest trajectory between the source and the collector electrodes. In this study, an alternative controlled deposition technique was proposed based on electric field manipulation (EFM). The main hypothesis of this study is that a consistent and repeatable method of controlled deposition can be achieved by using EFM. EFM was achieved by introducing a pair of charged auxiliary electrodes positioned adjacent and perpendicular to the fibre deposition direction. The applied voltage of either direct current (dc) or time-varying (ac) voltage at the auxiliary electrodes act as control to influence the spatial location and size of the deposition area. Samples were produced on black paper substrates and scanned into greyscale images. An image analysis technique was developed to measure the shift and size of the deposition area. A computer simulation was used to calculate the electric field strength and to simulate the behaviour of fibre response based on the trajectory of a charged particle. An image analysis based on greyscale intensity measurement was also developed to examine the uniformity of the deposition area. Finally, fibre characterisation was carried out to examine the fibre morphology, diameter, and orientation based on scanning electron micrographs. The results from this study showed that EFM can provide a consistent and repeatable control of the deposition area. When the auxiliary electrodes were independently charged with two dc voltages, it was observed that the deposition area moved away from the most positive electrode. The magnitude of shift of the deposition area was found to increase linearly with voltage difference between the auxiliary electrodes. Furthermore, the aspect ratio of the deposition area (ratio of width over height) decreased linearly with base voltage i.e. lower of the two auxiliary electrode voltages. These two controls were found to act independently from each other and can be described as two separate controls i.e. voltage difference for spatial location and base voltage for aspect ratio of the deposition area. A similar response was observed in simulation i.e. the particle moved away from the most positive electrode. Simulation results also showed that the x-axis component of the electric field (Ex) was responsible for the shift in location and the reduction of aspect ratio of the deposition area. When the auxiliary electrodes were charged with two antiphase time-varying voltages, continuous scanning of the electrospinning jet was observed producing a wide electrospun fibre mat. It was first thought the smooth oscillation of a sine wave would produce a more uniform deposition pattern compared to a triangle wave, but the results showed otherwise. The inferior uniformity of the sine wave sample was found due to the variability of the jet scanning speed when compared to the constant speed achieved when using a triangle wave. It was also observed that the deposition pattern can be further improved by using two clipped triangle wave voltages. The results open up the possibility for further exploiting the control voltage to achieve the desired deposition pattern. Two case studies were presented to demonstrate the applicability of the technique in real electrospinning applications. In the first case study, it was demonstrated that the continuous scanning of electrospinning jet was capable of eliminating the stripe deposition pattern which is commonly associated to a multi-spinneret electrospinning system. In the second case study, it was found that the alignment and distribution of aligned fibres in a gap electrospinning system can be improved by using the EFM technique. A new technique was also introduced to produce a multi-layer orientated fibre construct. These application examples showed that the EFM technique is ready for the production of engineered electrospun fibre constructs. This would extend the use of electrospun fibres to applications which is currently limited by geometrical constraints of the fibre constructs.

Two-dimensional numerical simulations of ablatively accelerated thin-shells subject to Rayleigh-Taylor instability are presented. Results for both single wavelength and multiwavelength perturbations show that the nonlinear effects of the instability are evident mainly in the "bubble" rather than the "spike." Approximate roles for predicting the dominant nonlinear mode-mode interactions, which limit shell performance, are also discussed. The work concludes with a discussion of recommendations for future work in this area.

Plant responses to abiotic stress are neither singular nor linear. The research represented within this dissertation was intended to evaluate selected biochemical and physiological responses in two Arugulas (Images 1-5), to agronomic interventions designed to mitigate extreme environmental abiotic factors, characteristic of arid agricultural production regions. Plant stress responses were investigated under field conditions and within controlled environments (CE), during the course of a preliminary trial and three independent studies, all four directly related. The preliminary trial evaluated harvest and postharvest nutritional content (i.e., antioxidants) of two Arugulas, Eruca sativa (L.) Cav. ssp. sativa (P. Mill.) and Diplotaxis tenuifolia (L.) DC cv. Sylvetta; grown under field conditions in the semi-arid upper Sonoran Desert. In this trial, we defined baseline harvest and postharvest antioxidant values for the Arugulas, cultivated in a semi-arid environment. The initial study, conducted within a CE utilizing a water recycling system, evaluated changes in the nutritional value of three specialty leafy cruciferous vegetables: D. tenuifolia, E. sativa and Lepidium sativum; when subjected to increasing salinity levels in the nutrient solution. It was concluded that, when specific Crucifers are irrigated with moderately high levels of salinity, neither harvest nor postharvest nutritional values are compromised. The second study, investigated the response of a suite of plant physiological parameters (e.g., yield and photosynthetic rate) in the three Crucifers to salinity, within the CE. This research provided guideline salinity values where yields did not decline, and encourages growers to consider water resources compromised by salinity and nutrient solution recycling. During the third study, the influence of environmental conditions on the nutritional content in leafy vegetables, prevalent immediately before harvest, was investigated; by subjecting plants to reduced sunlight treatments and early irrigation termination. We observed that, modulating light intensity late in the season, and early irrigation termination strategies, modify the nutritional content of leafy vegetables; and potentially the subsequent postharvest shelf life. Collectively evaluated, this research suggests that simple agronomic interventions are valuable, yet practicable, tools that can enhance the nutritional content of specialty vegetables, in arid regions: be that intervention an imposed controlled-stress, utilizing nutrient recycling systems within a CE, or basic light-reduction and irrigation termination strategies within conventional fields systems.

No description available.

Breastfeeding is recommended as the optimal source of nutrition for newborns for the first 6 months of life and beyond with the addition of complementary foods. While breastfeeding initiation rates have been increasing, duration rates remain a concern as many women prematurely discontinue due to difficulties encountered rather than maternal choice. In addition, there is a sizable gap between rates of exclusive breastfeeding and current recommendations. Targeting modifiable variables that may be amenable to intervention is one strategy to improve breastfeeding outcomes. One such modifiable variable is breastfeeding self-efficacy. Although research has clearly shown that breastfeeding self-efficacy is predictive of breastfeeding duration and exclusivity, it is unknown whether it can be enhanced to improve breastfeeding outcomes. The purpose of this pilot randomized controlled trial was to examine the feasibility and compliance of a newly developed trial protocol and the acceptability of an intervention to increase breastfeeding self-efficacy in the immediate postpartum period. Secondary outcomes included determining whether there were any trends between groups related to breastfeeding self-efficacy, duration, and exclusivity. Participants included 150 primiparous mothers who were breastfeeding their healthy, full-term infants. Eligible and consenting mothers were randomized to either a control group (standard postpartum care) or an intervention group (standard postpartum care plus the self-efficacy intervention). Participants allocated to the intervention group received three individualized, self-efficacy enhancing sessions with the researcher; two sessions were conducted in hospital, and one was administered via telephone 1 week following hospital discharge. A research assistant blinded to group allocation collected outcome data at 4 and 8 weeks postpartum. The results suggested that the administration of the intervention was feasible and that there was a high degree of protocol compliance; the majority of participants reported that the intervention was beneficial. Secondary outcomes identified that there was a trend among participants in the intervention group to have improved breastfeeding outcomes, including higher rates of breastfeeding self-efficacy, duration, and exclusivity at 4 and 8 weeks postpartum. Preliminary evidence also suggested that the self-efficacy intervention may have assisted to decrease perceptions of insufficient milk supply among the intervention group participants. Overall, the findings from this pilot trial indicated that a larger trial is warranted.

Hyperacusis is a type of decreased sound tolerance where the individual has decreased loudness discomfort levels (LDL), normal hearing thresholds and is sensitive to ordinary environmental sounds. Persons with hyperacusis frequently seek help at audiological departments as they are often affected by other audiological problems. Regrettably, there is neither a consensus-based diagnostic procedure nor an evidence-based treatment for hyperacusis. The principal aim of this thesis was to gain knowledge about the clinical condition hyperacusis. The specific aim of Paper I was to compare hyperacusis measurement tools in order to determine the most valid measures for assessing hyperacusis. Items from a constructed clinical interview were compared with the LDL test, the Hyperacusis Questionnaire (HQ) and the Hospital Anxiety and Depression Scale (HADS). LDLs were significantly correlated with the anxiety subscale of the HADS. A third of the 62 investigated patients scored below the previously recommended cut-off for the HQ. The results suggest that HQ and HADS in combination with a clinical interview are useful as part of the assessment procedure in patients with hyperacusis. The aim of Paper II was to further investigate the patient group with respect to individual characteristics, psychiatric morbidity and personality traits. It was shown that anxiety disorders and anxiety-related personality traits were over-represented, which suggests common or cooperating mechanisms. Avoidance behaviour proved to be very common in the patient group, as was being unable to work due to hyperacusis. In Paper III it was investigated in a randomized controlled trial whether Cognitive Behaviour Therapy (CBT) could be helpful for patients with hyperacusis. The effect of CBT for hyperacusis was assessed with measures of LDLs, symptoms of hyperacusis and of anxiety and depression, fear of (re)injury due to exposure to sounds, and quality of life, compared to a waiting list control group. There were significant group effects for a majority of the measures with moderate and strong effect sizes within- and between groups. After assessment the waiting list group was also given CBT, and was then reassessed with similar effects. The results were maintained for 12 months, concluding CBT to be potentially helpful for these patients.

Controlled release formulations deliver an active ingredient over an extended period of time. It is an ideal dosage form for an active ingredient with a short elimination half-life. An active ingredient with a short elimination half-life would be released in small portions over an extended period of time and thus less frequent administration is necessary and this improve patient compliance. Other advantages of these formulations include: decreased side effects, constant drug levels in the blood, improvement in treatment efficiency and reduction in cost of administration. Controlled release beads are formulated in such a way that the active ingredient is embedded in a matrix of insoluble substance like chitosan; the dissolving drug then has to find its way through the pores of the matrix into the surrounding medium. The chitosan matrix swells to form a gel, the drug then has to first dissolve in the matrix and diffuse through the outer surface into the surrounding medium. Chitosan is a biocompatible, biodegradable polymer of natural origin. It has mucoadhesive properties as well as the ability to manipulate the tight junctions in the epithelium membrane and these properties have qualified chitosan as an effective drug carrier in controlled release dosage forms. The effect of a modern controlled release polymer namely Kollidon® SR in combination with chitosan on drug release was investigated. Ketoprofen was chosen as model drug. Ketoprofen is an anti-inflammatory drug that causes gastrointestinal side effects in conventional dosage forms. Ketoprofen has a short elimination half-life of 2.05 ± 0.58 h and this characteristic makes it an ideal candidate for use in a controlled release formulation. The aim of this study was to achieve controlled release and minimize gastrointestinal effects of ketoprofen with chitosan particles. Kollidon® SR was used as polymer because it exhibits pH independent release characteristics and previous studies have shown potential for this combination. Chitosan beads and chitosan-Kollidon® SR beads, as well as chitosan granules and chitosan-Kollidon® SR granules, were prepared and investigated as potential controlled release formulations. Chitosan beads were prepared through the inotropic gelation method using tripolyphosphate as a cross linking agent. Granules were prepared through wet granulation using 2% v/v acetic acid as the granulating fluid or by dissolving ketoprofen in ethanol and Kollidon® SR in 2-pyrrolidinone and using the solution as granulating fluid. Kollidon® SR was added in concentrations of 0.25, 0.5 and 1% (w/v) in the bead formulations and concentrations of 1, 5 and 10% (w/w) in the granule formulations. The beads and granules were characterised by evaluating the following properties: morphology, drug loading and drug release. Additionally swelling and friability tests were also conducted on the bead formulations. The cross linking times of the bead formulations were varied to investigate the effect of cross linking time on the characteristics of the beads. Chitosan-Kollidon® SR beads showed promising results for controlled release formulations and ketoprofen were released over an extended period of time. Drug loading of the plain chitosan beads was 74.65 ± 0.71% and it was noted that the inclusion of Kollidon® SR in the beads resulted in an increase in drug loading and the formulation containing 1% (w/v) Kollidon® SR, cross linked for 30 minutes had a drug loading of 77.38 ± 0.01%. Drug loading of the beads that were cross linked for a longer time were slightly lower which is an indication that some of the drug might have leached out during cross linking. The degree of swelling was promising with some beads swelling to a degree of 2.5 in phosphate buffer solution pH 5.6. Granules had a drug loading between 81.73 ± 1.53% and 93.30 ± 0.50%. Ketoprofen release from the beads and the granules in PBS pH 7.40 at 37 °C over a period of 6 hours were investigated. The bead formulations were more effective in achieving controlled release and it was noted that the bead formulations that was cross linked for a longer period was more efficient in achieving controlled release. The granules did not form a matrix and were not effective in achieving controlled release. Controlled release of ketoprofen were achieved and the results show potential for chitosan-Kollidon® SR formulations in the future. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2008.

This thesis concerns the relationship between bounded and controlled topology and in particular how these can be used to recognise which homotopy equivalences of reasonable topological spaces are homotopic to homeomorphisms. Let f : X → Y be a simplicial map of finite-dimensional locally finite simplicial complexes. Our first result is that f has contractible point inverses if and only if it is an ε- controlled homotopy equivalences for all ε > 0, if and only if f × id : X × R → Y × R is a homotopy equivalence bounded over the open cone O(Y +) of Pedersen and Weibel. The most difficult part, the passage from contractible point inverses to bounded over O(Y +) is proven using a new construction for a finite dimensional locally finite simplicial complex X, which we call the fundamental ε-subdivision cellulation X'ε. This whole approach can be generalised to algebra using geometric categories. In the second part of the thesis we again work over a finite-dimensional locally finite simplicial complex X, and use the X-controlled categories A*(X), A*(X) of Ranicki and Weiss (1990) together with the bounded categories CM(A) of Pedersen and Weibel (1989). Analogous to the barycentric subdivision of a simplicial complex, we define the algebraic barycentric subdivision of a chain complex over that simplicial complex. The main theorem of the thesis is then that a chain complex C is chain contractible in ( A*(X) A*(X) if and only if “C ¤ Z” 2 (A*(X × R) A*(X × R) is boundedly chain contractible when measured in O(X+) for a functor “ − Z” defined appropriately using algebraic subdivision. In the process we prove a squeezing result: a chain complex with a sufficiently small chain contraction has arbitrarily small chain contractions. The last part of the thesis draws some consequences for recognising homology manifolds in the homotopy types of Poincare Duality spaces. Squeezing tells us that a PL Poincare duality space with sufficiently controlled Poincare duality is necessarily a homology manifold and the main theorem tells us that a PL Poincare duality space X is a homology manifold if and only if X × R has bounded Poincare duality when measured in the open cone O(X+).

International Telemetering Conference Proceedings / October 26-29, 1992 / Town and Country Hotel and Convention Center, San Diego, California / The MicroDAS-1000 is an airborne Data Acquisition System (DAS) designed to meet the growing needs of airframe manufacturers for extensive test data accumulation, processing and evaluation. As such, the system has been designed with emphasis on modularity, miniaturization and ease of operator usage and expansion. The MicroDAS product line includes a series of components used as building blocks to configure systems of virtually any size. The modular design of these components allows considerable latitude to the instrumentation engineer in configuring systems for simple or complex applications. The modular concept has been extended to the design of plug-in modules for different functional requirements and system applications. All units are under software control to allow rapid reconfiguration and setup as requirements for instrumentation and data gathering change.

Background: The Selenium and Vitamin E Cancer Prevention Trial (SELECT) was a randomized, double-blind, placebo-controlled, prostate cancer prevention study funded by the National Cancer Institute and conducted by SWOG (Southwest Oncology Group). A total of 35,533 men were assigned randomly to one of four treatment groups (vitamin E + placebo, selenium + placebo, vitamin E + selenium, placebo + placebo). At the time of the trial's development, NIH had invested substantial resources in evaluating the potential benefits of these antioxidants. To capitalize on the knowledge gained from following a large cohort of healthy, aging males on the effects of selenium and/or vitamin E, ancillary studies with other disease endpoints were solicited. Methods: Four ancillary studies were added. Each drew from the same population but had independent objectives and an endpoint other than prostate cancer. These studies fell into two categories: those prospectively enrolling and following participants (studies of Alzheimer's disease and respiratory function) and those requiring a retrospective medical record review after a reported event (cataracts/age-related macular degeneration and colorectal screening). An examination of the challenges and opportunities of adding ancillary studies is provided. The impact of the ancillary studies on adherence to SELECT was evaluated using a Cox proportional hazards model. Results: While the addition of ancillary studies appears to have improved participant adherence to the primary trial, this did not come without added complexity. Activation of the ancillary studies happened after the SELECT randomizations had begun resulting in accrual problems to some of the studies. Study site participation in the ancillary trials varied greatly and depended on the interest of the study site principal investigator. Procedures for each were integrated into the primary trial and all monitoring was done by the SELECT Data and Safety Monitoring Committee. The impact of the early closure of the primary trial was different for each of the ancillary trials. Conclusions: The ancillary studies allowed study sites to broaden the research opportunities for their participants. Their implementation was efficient because of the established infrastructure of the primary trial. Implementation of these ancillary trials took substantial planning and coordination but enriched the overall primary trial.