A wave equation technique for designing compact gradient coils

A primary purpose of this research is to design a gradient coil that is planar in construction and can be inserted within existing infrastructure. The proposed wave equation method for the design of gradient coils is novel within the field. it is comprehensively shown how this method can be used to design the planar x-, y-, and z-gradient wire windings to produce the required magnetic fields within a certain domain. The solution for the cylindrical gradient coil set is also elucidated. The wave equation technique is compared with the well-known target held method to gauge the quality of resultant design. In the case of the planar gradient coil design, it is shown that using the new method, a set of compact gradient coils with large field of view can be produced. The final design is considerably smaller in dimension when compared with the design obtained using the target field method, and therefore the manufacturing costs and materials required are somewhat reduced.

Daily sunscreen application and betacarotene supplementation in prevention of basal-cell and squamous-cell carcinomas of the skin: a randomised controlled trial

Background The use of sunscreens on the skin can prevent sunburn but whether long-term use can prevent skin cancer is not known. Also, there is evidence that oral betacarotene supplementation lowers skin-cancer rates in animals, but there is limited evidence of its effect in human beings. Methods In a community-based randomised trial with a 2 by 2 factorial design, individuals were assigned to four treatment groups: daily application of a sun protection factor 15-plus sunscreen to the head, neck, arms, and hands, and betacarotene supplementation (30 mg per day); sunscreen plus placebo tablets; betacarotene only; or placebo only. Participants were 1621 residents of Nambour in southeast Queensland, Australia. The endpoints after 4.5 years of follow-up were the incidence of basal-cell and squamous-cell carcinomas both in terms of people treated for newly diagnosed disease and in terms of the numbers of tumours that occurred. Analysis of the effect of sunscreen was based only on skin cancers that developed on sites of daily application. All analyses were by intention to treat. Findings 1383 participants underwent full shin examination by a dermatologist in the follow-up period. 250 of them developed 758 new skin cancers during the follow-up period. There were no significant differences in the incidence of first new shin cancers between groups randomly assigned daily sunscreen and no daily sunscreen (basal-cell carcinoma 2588 vs 2509 per 100 000; rate ratio 1.03 [95% CI 0.73-1.46]; squamous-cell carcinoma 876 vs 996 per 100 000; rate ratio 0.88 [0.50-1.56]). Similarly, there was no significant difference between the betacarotene and placebo groups in incidence of either cancer (basal-cell carcinoma 3954 vs 3806 per 100 000; 1.04 [0.73-1.27]; squamous-cell carcinoma 1508 vs 1146 per 100 000; 1.35 [0.84-2.19]). In terms of the number of tumours, there was no effect on incidence of basal-cell carcinoma by sunscreen use or by betacarotene but the incidence of squamous-cell carcinoma was significantly lower in the sunscreen group than in the no daily sunscreen group (1115 vs 1832 per 100 000; 0.61 [0.46-0.81]). Interpretation There was no harmful effect of daily use of sunscreen in this medium-term study. Cutaneous squamous-cell carcinoma, but not basal-cell carcinoma seems to be amenable to prevention through the routine use of sunscreen by adults for 4.5 years. There was no beneficial or harmful effect on the rates of either type of skin cancer, as a result of betacarotene supplementation.

Novel formulation strategies for the fabrication of lyophilised orally disintegrating tablets

Orally disintegrating Tablets (ODTs), also known as fast-disintegrating, fast-melt or fast-dissolving tablets, are a relatively novel dosage technology that involves the rapid disintegration or dissolution of the dosage form into a solution or suspension in the mouth without the need for water. The solution containing the active ingredients is swallowed, and the active ingredients are then absorbed through the gastrointestinal epithelium to reach the target and produce the desired effect. Formulation of ODTs was originally developed to address swallowing difficulties of conventional solid oral dosage forms (tablets and capsules) experienced by wide range of patient population, especially children and elderly. The current work investigates the formulation and development of ODTs prepared by freeze drying. Initial studies focused on formulation parameters that influence the manufacturing process and performance of lyophilised tablets based on excipients used in commercial products (gelatin and saccharides). The second phase of the work was followed up by comprehensive studies to address the essential need to create saccharide free ODTs using naturally accruing amino acids individually or in combinations. Furthermore, a factorial design study was carried out to investigate the feasibility of delivering multiparticulate systems of challenging drugs using a novel formulation that exploited the electrostatic associative interaction between gelatin and carrageenan. Finally, studies aimed to replace gelatin with ethically and morally accepted components to the end users were performed and the selected binder was used in factorial design studies to investigate and optimise ODT formulations that incorporated drugs with varies physicochemical properties. Our results show that formulation of elegant lyophilised ODTs with instant disintegration and adequate mechanical strength requires carful optimisation of gelatin concentration and bloom strength in addition to saccharide type and concentration. Successful formulation of saccharides free lyophilised ODTs requires amino acids that crystallise in the frozen state or display relatively high Tg', interact and integrate completely with the binder and, also, display short wetting time with the disintegrating medium. The use of an optimised mixture of gelatin, carrageenan and alanine was able to create viscous solutions to suspend multiparticulate systems and at the same time provide tablets with short disintegration times and adequate mechanical properties. On the other hand, gum arabic showed an outstanding potential for use as a binder in the formulation of lyophilised ODTs. Compared to gelatin formulations, the use of gum arabic simplified the formulation stages, shortened the freeze drying cycles and produced tablets with superior performance in terms of the disintegration time and mechanical strength. Furthermore, formulation of lyophilised ODTs based on gum arabic showed capability to deliver diverse range of drugs with advantages over commercial products.

The development and investigation of a novel pulsatile heart assist device

Cardiovascular diseases (CVD) contributed to almost 30% of worldwide mortality; with heart failure being one class of CVD. One popular and widely available treatment for heart failure is the intra-aortic balloon pump (IABP). This heart assist device is used in counterpulsation to improve myocardial function by increasing coronary perfusion, and decreasing aortic end-diastolic pressure (i.e. the resistance to blood ejection from the heart). However, this device can only be used acutely, and patients are bedridden. The subject of this research is a novel heart assist treatment called the Chronic Intermittent Mechanical Support (CIMS) which was conceived to offer advantages of the IABP device chronically, whilst overcoming its disadvantages. The CIMS device comprises an implantable balloon pump, a percutaneous drive line, and a wearable driver console. The research here aims to determine the haemodynamic effect of balloon pump activation under in vitro conditions. A human mock circulatory loop (MCL) with systemic and coronary perfusion was constructed, capable of simulating various degrees of heart failure. Two prototypes of the CIMS balloon pump were made with varying stiffness. Several experimental factors (balloon inflation/deflation timing, Helium gas volume, arterial compliance, balloon pump stiffness and heart valve type) form the factorial design experiments. A simple modification to the MCL allowed flow visualisation experiments using video recording. Suitable statistical tests were used to analyse the data obtained from all experiments. Balloon inflation and deflation in the ascending aorta of the MCL yielded favourable results. The sudden balloon deflation caused the heart valve to open earlier, thus causing longer valve opening duration in a cardiac cycle. It was also found that pressure augmentation in diastole was significantly correlated with increased cardiac output and coronary flowrate. With an optimum combination (low arterial compliance and low balloon pump stiffness), systemic and coronary perfusions were increased by 18% and 21% respectively, while the aortic end-diastolic pressure (forward flow resistance) decreased by 17%. Consequently, the ratio of oxygen supply and demand to myocardium (endocardial viability ratio, EVR) increased between 33% and 75%. The increase was mostly attributed to diastolic augmentation rather than systolic unloading.

Formulation and process engineering of freeze-dried orally disintegrating tablets

Orally disintegrating tablets (ODTs) which are also referred to as orodispersible and fast disintegrating tablets, are solid oral dosage forms which upon placing on the tongue, disperse/disintegrate rapidly before being swallowed as a suspension or solution. ODTs are therefore easier and more convenient to administer than conventional tablets and are particularly beneficial for paediatric and geriatric patients, who generally have difficulty swallowing their medication. The work presented in this thesis involved the formulation and process development of ODTs, prepared using freeze-drying. Gelatin is one of the principal excipients used in the formulation of freeze-dried ODTs. One of the studies presented in this thesis investigated the potential modification of the properties of this excipient, in order to improve the performance of the tablets. As gelatin is derived from animal sources, a number of ethical issues surround its use as an excipient in pharmaceutical preparations. This was one of the motivations, Methocel™ and Kollicoat® IR were evaluated as binders as alternative materials to gelatin. Polyox™ was also evaluated as a binder together with its potential uses as a viscosity increasing and mucoadhesive agent to increase the retention of tablets in the mouth to encourage pre-gastric absorption of active pharmaceutical ingredients (APIs). The in vitro oral retention of freeze-dried ODT formulations was one property which was assessed in a design of experiments – factorial design study, which was carried out to further understand the role that formulation excipients have on the properties of the tablets. Finally, the novel approach of incorporating polymeric nanoparticles in freeze-dried ODTs was investigated, to study if the release profile of APIs could be modified, which could improve their therapeutic effect. The results from these studies demonstrated that the properties of gelatin-based formulations can be modified by adjusting pH and ionic strength. Adjustment of formulation pH has shown to significantly reduce tablet disintegration time. Evaluating Methocel™, in particular low viscosity grades, and Kollicoat® IR as binders has shown that these polymers can form tablets of satisfactory hardness and disintegration time. Investigating Polyox™ as an excipient in freeze-dried ODT formulations revealed that low viscosity grades appear suitable as binders whilst higher viscosity grades could potentially be utilised as viscosity increasing and mucoadhesive agents. The design of experiments – factorial design study revealed the influence of individual excipients in a formulation mix on resultant tablet properties and in vitro oral retention of APIs. Novel methods have been developed, which allows the incorporation of polymeric nanoparticles in situ in freeze-dried ODT formulations, which allows the modification of the release profile of APIs.

Structural optimization

The non-linear programming algorithms for the minimum weight design of structural frames are presented in this thesis. The first, which is applied to rigidly jointed and pin jointed plane frames subject to deflexion constraints, consists of a search in a feasible design space. Successive trial designs are developed so that the feasibility and the optimality of the designs are improved simultaneously. It is found that this method is restricted lo the design of structures with few unknown variables. The second non-linear programming algorithm is presented .in a general form. This consists of two types of search, one improving feasibility and the other optimality. The method speeds up the 'feasible direction' approach by obtaining a constant weight direction vector that is influenced by dominating constraints. For pin jointed plane and space frames this method is used to obtain a 'minimum weight' design which satisfies restrictions on stresses and deflexions. The matrix force method enables the design requirements to be expressed in a general form and the design problem is automatically formulated within the computer. Examples are given to explain the method and the design criteria are extended to include member buckling. Fundamental theorems are proposed and proved to confirm that structures are inter-related. These theorems are applicable to linear elastic structures and facilitate the prediction of the behaviour of one structure from the results of analysing another, more general, or related structure. It becomes possible to evaluate the significance of each member in the behaviour of a structure and the problem of minimum weight design is extended to include shape. A method is proposed to design structures of optimum shape with stress and deflexion limitations. Finally a detailed investigation is carried out into the design of structures to study the factors that influence their shape.

Factors influencing consumer evaluations of gift promotions

Purpose: The aim of this paper is to shed light on the determinants of consumers' evaluations and purchase intentions of gift promotions. Factors analysed relate to the promoted product, the gift, the relationship between the product and the gift, and consumer traits and perceptions. Design/methodology/approach: A 2 (product type: utilitarian vs hedonic) × 2 (gift type: utilitarian vs hedonic) × 2 (brand type: high equity vs medium equity) between-subjects factorial design was undertaken. Structural equation modelling was used to test the hypotheses on a sample of 247 respondents in the UK. Findings: Gift attractiveness is the most important driver of consumers' overall evaluation of gift promotions, followed by the attitude toward the promoted brand, the perceived fit between the promoted product and the gift, the hedonic nature of the gift, plus value expression and entertainment benefits perceived by consumers. Results also reveal that deal proneness is positively associated with the hedonic benefits of value expression benefit and entertainment benefit. Finally, the overall evaluation of gift promotions with both brand attitudes and deal proneness positively influences consumers' purchase intentions. Research limitations/implications: To generalise these findings, future research should use a wider sample. Practical implications: The findings of this study provide guidelines for marketers designing their gift promotional strategies. Originality/value: The increased popularity of gift promotions necessitates a better understanding of the factors influencing consumers' evaluations. This study addresses the lack of research in this area by simultaneously investigating the effect of different key factors. © Emerald Group Publishing Limited.

Open Source Information Technologies Approach for Moddeling of Ankle-Foot Orthosis

Computer modeling is a perspective method for optimal design of prosthesis and orthoses. The study is oriented to develop modular ankle foot orthosis (MAFO) to assist the very frequently observed gait abnormalities relating the human ankle-foot complex using CAD modeling. The main goal is to assist the ankle- foot flexors and extensors during the gait cycle (stance and swing) using torsion spring. Utilizing 3D modeling and animating open source software (Blender 3D), it is possible to generate artificially different kind of normal and abnormal gaits and investigate and adjust the assistive modular spring driven ankle foot orthosis.

Developing an intervention to equip nurses for acute life threatening events (ALTEs) in hospital:a phenomenological approach to healthcare research

Objectives: To understand staff's experiences of acute life threatening events (ALTEs) in a pediatric hospital setting. These data will inform an intervention to equip nurses with clinical and emotional skills for dealing with ALTEs. Method: A mixed design was used in the broader research program; this paper focuses on phenomenon-focused interviews analyzed using interpretative phenomenological analysis (IPA). Results: Emerging themes included staff's relationships with patients and the impact of personhood on their ability to perform competently in an emergency. More experienced nurses described "automatic" competence generated through increased exposure to ALTEs and were able to recognize "fumbling and shaking" as a normal stress response. Designating a role was significant to staff experience of effectiveness. Key to nurses' learning experience was reflection and identifying experiences as "teachable moments." Findings were considered alongside existing theories of self-efficacy, reflective thought, and advocacy inquiry to create an experiential learning intervention involving a series of clinical and role-related scenarios. Conclusion: The phenomenological work facilitated an in-depth reading of experience. It accentuated the importance of exposure to ALTEs giving nurses experiential knowledge to prepare them for the impact of these events. Challenges included bracketing the personhood of child patients, shifting focus to clinical tasks during the pressured demands of managing an ALTE, normalizing the physiological stress response, and the need for a forum and structure for reflection and learning. An intervention will be designed to provide experiential learning and encourage nurses to realize and benefit from their embodied knowledge.

Cross-national differences in e-WOM influence

Purpose: This paper aims to present a cross-national study that investigates changes in purchase intentions of UK versus Chinese consumers following exposure to successive e-WOM comments in the form of positive and negative user reviews for experience versus search products. Design/methodology/approach: A 2(e-WOM valence and order: negative versus positive most recent)×2(product type: experience versus search)×3(purchase intentions at t 1, t 2, t 3) repeated-measures factorial design is used to test a set of hypotheses developed from the literature. Findings: Chinese consumers are susceptible to recent e-WOM comments regardless of their valence, while UK consumers anchor on negative information regardless of the order in which it is acquired. This holds particularly for experience products. Originality/value: This cross-national study contributes to the scarce literature on the impact of e-WOM on consumer purchase decisions by comparing UK and Chinese consumers. The authors suggest that culture moderates the development of product evaluations following exposure to e-WOM. © Emerald Group Publishing Limited.

A geometrical model for surface roughness prediction when face milling Al 7075-T7351 with square insert tools

Surface quality is important in engineering and a vital aspect of it is surface roughness, since it plays an important role in wear resistance, ductility, tensile, and fatigue strength for machined parts. This paper reports on a research study on the development of a geometrical model for surface roughness prediction when face milling with square inserts. The model is based on a geometrical analysis of the recreation of the tool trail left on the machined surface. The model has been validated with experimental data obtained for high speed milling of aluminum alloy (Al 7075-T7351) when using a wide range of cutting speed, feed per tooth, axial depth of cut and different values of tool nose radius (0.8. mm and 2.5. mm), using the Taguchi method as the design of experiments. The experimental roughness was obtained by measuring the surface roughness of the milled surfaces with a non-contact profilometer. The developed model can be used for any combination of material workpiece and tool, when tool flank wear is not considered and is suitable for using any tool diameter with any number of teeth and tool nose radius. The results show that the developed model achieved an excellent performance with almost 98% accuracy in terms of predicting the surface roughness when compared to the experimental data. © 2014 The Society of Manufacturing Engineers.

How doctors' communication style and race concordance influence African-Caribbean patients when disclosing depression

Objective: To determine the impact of doctors' communication style and doctor-patient race concordance on UK African-Caribbeans' comfort in disclosing depression. Methods: 160 African-Caribbean and 160 white British subjects, stratified by gender and history of depression, participated in simulated depression consultations with video-recorded doctors. Doctors were stratified by black or white race, gender and a high (HPC) or low patient-centred (LPC) communication style, giving a full 2. ×. 2. ×. 2 factorial design. Afterwards, participants rated aspects of doctors' communication style, their comfort in disclosing depression and treatment preferences. Results: Race concordance had no impact on African-Caribbeans' comfort in disclosing depression. However a HPC versus LPC communication style made them significantly more positive about their interactions with doctors (p = 0.000), their overall comfort (p = 0.003), their comfort in disclosing their emotional state (p = 0.001), and about considering talking therapy (p = 0.01); but less positive about considering antidepressant medication (p =0.01). Conclusion: Doctors' communication style was shown to be more important than patient race or race concordance in influencing African Caribbeans' depression consultation experiences. Changing doctors' communication style may help reduce disparities in depression care. Practice Implications: Practitioners should cultivate a HPC style to make African-Caribbeans more comfortable when disclosing depression, so that it is less likely to be missed.

Consumer response to gift promotions

Purpose: The objective of this paper is to better understand the factors that influence consumers' responses toward gift promotions. Specifically, the aim is to analyse four variables: the nature of the promoted product, the fit between the product and the gift, the type of brand used in the promotion and the deal-proneness. Design/methodology/approach: In an experimental context, 247 subjects were randomly assigned to a 2 (product type: utilitarian vs hedonic)×2 (gift type: utilitarian vs hedonic)×2 (brand type: high equity vs medium equity) between-subjects factorial design. Findings: Results indicate that the nature of the promoted product does not influence consumer response. Overall evaluation of gift promotions is more favourable when simultaneously the brand promoted has high equity and the fit between the promoted product and the gift is high. Offering a gift that fits with the product and using high equity brands is a wise strategy to positively influence purchase intentions. Findings also show that deal proneness has a positive impact on purchase intentions. Research limitations/implications: A limited set of product categories, gifts and brands were used. Future research should also examine other variables and use a representative sample. Practical implications: Findings provide useful guidelines for the design of gift promotions. Originality/value: Most previous research has focused on monetary promotions with little about non-monetary promotions. This paper addresses this gap by analysing consumers' responses to gift promotions incorporating key determinants in the analysis. © Emerald Group Publishing Limited.

Changes in intraocular pressure in study and fellow eyes in the IVAN trial

PURPOSE: To describe changes in intraocular pressure (IOP) in the 'alternative treatments to Inhibit VEGF in Age-related choroidal Neovascularisation (IVAN)' trial (registered as ISRCTN92166560). DESIGN: Randomised controlled clinical trial with factorial design. PARTICIPANTS: Patients (n=610) with treatment naïve neovascular age-related macular degeneration were enrolled and randomly assigned to receive either ranibizumab or bevacizumab and to two regimens, namely monthly (continuous) or as needed (discontinuous) treatment. METHODS: At monthly visits, IOP was measured preinjection in both eyes, and postinjection in the study eye. OUTCOME MEASURES: The effects of 10 prespecified covariates on preinjection IOP, change in IOP (postinjection minus preinjection) and the difference in preinjection IOP between the two eyes were examined. RESULTS: For every month in trial, there was a statistically significant rise in both the preinjection IOP and the change in IOP postinjection during the time in the trial (estimate 0.02 mm Hg, 95% CI 0.01 to 0.03, p<0.001 and 0.03 mm Hg, 95% CI 0.01 to 0.04, p=0.002, respectively). There was also a small but significant increase during the time in trial in the difference in IOP between the two eyes (estimate 0.01 mm Hg, 95% CI 0.005 to 0.02, p<0.001). There were no differences between bevacizumab and ranibizumab for any of the three outcomes (p=0.93, p=0.22 and p=0.87, respectively). CONCLUSIONS: Anti-vascular endothelial growth factor agents induce increases in IOP of small and uncertain clinical significance.

The special case of self-perspective inhibition in mental, but not non-mental, representation

The ventrolateral prefrontal cortex (vlPFC) has been implicated in studies of both executive and social functions. Recent meta-analyses suggest that vlPFC plays an important but little understood role in Theory of Mind (ToM). Converging neuropsychological and functional Magnetic Resonance Imaging (fMRI) evidence suggests that this may reflect inhibition of self-perspective. The present study adapted an extensively published ToM localizer to evaluate the role of vlPFC in inhibition of self-perspective. The classic false belief, false photograph vignettes that comprise the localizer were modified to generate high and low salience of self-perspective. Using a factorial design, the present study identified a behavioural and neural cost associated with having a highly salient self-perspective that was incongruent with the representational content. Importantly, vlPFC only differentiated between high versus low salience of self-perspective when representing mental state content. No difference was identified for non-mental representation. This result suggests that different control processes are required to represent competing mental and non-mental content.