Creating a computational tool to simulate vibration control for piezoelectric devices

Piezoelectric materials have the unique ability to convert electrical energy to mechanical vibrations and vice versa. This project takes a stab to develop a reliable computational tool to simulate the vibration control of a novel “partial differential equation” model for a piezoelectric device, which is designed by integrating electric conducting piezoelectric layers constraining a viscoelastic layer to provide an active and lightweight intelligent structure. Controlling unwanted vibrations on piezoelectric devices (or harvesting energy from ambient vibrations) through piezoelectric layers has been the major focus in cutting-edge engineering applications such as ultrasonic welders and inchworms. The corresponding mathematical models for piezoelectric devices are either heuristic or mathematically oversimplified differential equations. Moreover, their “unjustified” approximated reductions consider only the first several vibrations on these devices. In this project, a novel partial differential equation model, accounting for all vibrational modes, is analyzed to provide new insights for a cost-efficient sensor feedback design. Therefore, the sensor feedback signals are not allowed to be contaminated by the residual modes. Our primary goal is to develop reproducible computational tools by an emerging stable approximation technique, so-called filtered Finite Difference Method, which is proved to provide faster and reliable computation. Filtering in the approximation is necessary since the spurious vibrations, due to the blind application of the Finite Difference Method, provide a false stability result. To see the efficiency of the algorithm, we compare the approximation to the one obtained by the Finite Element Method based on the Galerkin\u27s approximation, which is a common technique being used in the engineering literature. The mathematical techniques and computational tools developed in this project are essential to provide new insights into the active controlling of piezoelectric devices. Improving the efficiency of active controlling enables us to take better advantage of piezoelectric technology change since one-time design and fabrication may be unavoidable for many applications such as cardiac pacemakers or NASA/commercially-operated inflatable space antennas. Our state-of-the-art partial differential equation model and its stable approximations will be adaptable for a large class of piezoelectric devices

The clinical effectiveness and cost-effectiveness of ablative therapies in the management of liver metastases: systematic review and economic evaluation

Background: Many deaths from cancer are caused by metastatic burden. Prognosis and survival rates vary, but survival beyond 5 years of patients with untreated metastatic disease in the liver is rare. Treatment for liver metastases has largely been surgical resection, but this is feasible in only approximately 20–30% of people. Non-surgical alternatives to treat some liver metastases can include various forms of ablative therapies and other targeted treatments.Objectives: To evaluate the clinical effectiveness and cost-effectiveness of the different ablative and minimally invasive therapies for treating liver metastases.Data sources: Electronic databases including MEDLINE, EMBASE and The Cochrane Library were searched from 1990 to September 2011. Experts were consulted and bibliographies checked.Review methods: Systematic reviews of the literature were undertaken to appraise the clinical effectiveness and cost-effectiveness of ablative therapies and minimally invasive therapies used for people with liver metastases. Studies were any prospective study with sample size greater than 100 participants. A probabilistic model was developed for the economic evaluation of the technologies where data permitted.Results: The evidence assessing the clinical effectiveness and cost-effectiveness of ablative and other minimally invasive therapies was limited. Nine studies of ablative therapies were included in the review; each had methodological shortcomings and few had a comparator group. One randomised controlled trial (RCT) of microwave ablation versus surgical resection was identified and showed no improvement in outcomes compared with resection. In two prospective case series studies that investigated the use of laser ablation, mean survival ranged from 41 to 58 months. One cohort study compared radiofrequency ablation with surgical resection and five case series studies also investigated the use of radiofrequency ablation. Across these studies the median survival ranged from 44 to 52 months. Seven studies of minimally invasive therapies were included in the review. Two RCTs compared chemoembolisation with chemotherapy only. Overall survival was not compared between groups and methodological shortcomings mean that conclusions are difficult to make. Two case series studies of laser ablation following chemoembolisation were also included; however, these provide little evidence of the use of these technologies in combination. Three RCTs of radioembolisation were included. Significant improvements in tumour response and time to disease progression were demonstrated; however, benefits in terms of survival were equivocal. An exploratory survival model was developed using data from the review of clinical effectiveness. The model includes separate analyses of microwave ablation compared with surgery and radiofrequency ablation compared with surgery and one of radioembolisation in conjunction with hepatic artery chemotherapy compared with hepatic artery chemotherapy alone. Microwave ablation was associated with an incremental cost-effectiveness ratio (ICER) of £3664 per quality-adjusted life-year (QALY) gained, with microwave ablation being associated with reduced cost but also with poorer outcome than surgery. Radiofrequency ablation compared with surgical resection for solitary metastases < 3 cm was associated with an ICER of –£266,767 per QALY gained, indicating that radiofrequency ablation dominates surgical resection. Radiofrequency ablation compared with surgical resection for solitary metastases ? 3 cm resulted in poorer outcomes at lower costs and a resultant ICER of £2538 per QALY gained. Radioembolisation plus hepatic artery chemotherapy compared with hepatic artery chemotherapy was associated with an ICER of £37,303 per QALY gained.Conclusions: There is currently limited high-quality research evidence upon which to base any firm decisions regarding ablative therapies for liver metastases. Further trials should compare ablative therapies with surgery, in particular. A RCT would provide the most appropriate design for undertaking any further evaluation and should include a full economic evaluation, but the group to be randomised needs careful selection.Source of funding: Funding for this study was provided by the Health Technology Assessment programme of the National Institute for Health Research

Managing the screen-viewing behaviours of 5-6 year old children:a qualitative analysis of parental strategies

OBJECTIVES: The present study used qualitative methods to: (1) examine the strategies that were used by parents of children aged 5–6 years to manage screen viewing; (2) identify key factors that affect the implementation of the strategies and (3) develop suggestions for future intervention content. DESIGN: Telephone interviews were conducted with parents of children aged 5–6 years participating in a larger study. Interviews were transcribed verbatim and analysed using an inductive and deductive content analysis. Coding and theme generation was iterative and refined throughout. SETTING: Parents were recruited through 57 primary schools located in the greater Bristol area (UK). PARTICIPANTS: 53 parents of children aged 5–6 years. RESULTS: Parents reported that for many children, screen viewing was a highly desirable behaviour that was difficult to manage, and that parents used the provision of screen viewing as a tool for reward and/or punishment. Parents managed screen viewing by setting limits in relation to daily events such as meals, before and after school, and bedtime. Screen-viewing rules were often altered depending on parental preferences and tasks. Inconsistent messaging within and between parents represented a source of conflict at times. Potential strategies to facilitate reducing screen viewing were identified, including setting screen-viewing limits in relation to specific events, collaborative rule setting, monitoring that involves mothers, fathers and the child, developing a family-specific set of alternative activities to screen viewing and developing a child's ability to self-monitor their own screen viewing. CONCLUSIONS: Managing screen viewing is a challenge for many parents and can often cause tension in the home. The data presented in this paper provide key suggestions of new approaches that could be incorporated into behaviour change programmes to reduce child screen viewing

Pharmacological therapies for fibromyalgia (fibromyalgia syndrome) in adults – an overview of Cochrane Reviews (Protocol).

This is a protocol for a Cochrane Review (overview). The objectives are as follows:To provide an overview of the therapeutic efficacy of pharmacological therapies for fibromyalgia (fibromyalgia syndrome) in adults, and to report on adverse events associated with their use. The major comparison of interest will be with placebo

How parents perceive screen viewing in their 5-6 year old child within the context of their own screen viewing time:a mixed-methods study

Abstract Background Few studies have examined parental perceptions of their child’s screen-viewing (SV) within the context of parental SV time. This study qualitatively examined parents’ perceptions of their 5–6-year-old child’s SV within the context of their own quantitatively measured SV. Methods A mixed-methods design employed semi-structured telephone interviews, demographic and SV questionnaires, objectively-measured physical activity and sedentary time. Deductive content analysis was used to explore parents’ perceptions of, and concerns about, their child’s SV, and management of their child’s SV. Comparisons were made between parent-child dyads reporting low (<2-h per day) versus high SV time. Results Fifty-three parents were interviewed (94.3% mothers), with 52 interviews analysed. Fifteen parent-child dyads (28.8%) exceeded the 2-h SV threshold on both weekdays and weekend days; 5 parent-child dyads (9.6%) did not exceed this threshold. The remaining 32 dyads reported a combination of parent or child exceeding/not exceeding the SV threshold on either weekdays or weekend days. Three main themes distinguished the 15 parent-child dyads exceeding the SV threshold from the 5 dyads that did not: 1) parents’ personal SV-related views and behaviours; 2) the family SV environment; and 3) setting SV rules and limits. Parents in the dyads not exceeding the SV threshold prioritized and engaged with their children in non-SV behaviours for relaxation, set limits around their own and their child’s SV-related behaviours, and described an environment supportive of physical activity. Parents in the dyads exceeding the SV threshold were more likely to prioritise SV as a shared family activity, and described a less structured SV environment with minimal rule setting, influenced their child’s need for relaxation time. Conclusions The majority of parents in this study who exceeded the SV threshold expressed minimal concern and a relaxed approach to managing SV for themselves and their child(ren), suggesting a need to raise awareness amongst these parents about the time they spend engaging in SV. Parents may understand their SV-related parenting practices more clearly if they are encouraged to examine their own SV behaviours. Designing interventions aimed to create environments that are less supportive of SV, with more structured approaches to SV parenting strategies are warranted