Security-constrained unit commitment with natural gas pipeline transient constraints

The interdependencies of power systems and natural gas networks have increased due to the additional installations of more environmental-friendly and fast-ramping natural gas power plants. The natural gas transmission network constraints and the use of natural gas for other types of loads can affect the delivery of natural gas to generation units. These interdependencies will affect the power system security and economics in day-ahead and real-time operations. Hence, it is imperative to analyze the impact of natural gas network constraints on the security-constrained unit commitment (SCUC) problem. In particular, it is important to include natural gas and electricity network transients in the integrated system security because the impacts of any disturbances propagate at two distinctly different speeds in natural gas and electricity networks. Thus, analyzing the transient behavior of the natural gas network on the security of natural gas power plants would be essential as these plants are considered to be very flexible in electricity networks. This paper presents a method for solving the SCUC problem considering the transient behavior of the natural gas transmission network. The applicability of the presented method and the accuracy of the proposed solution are demonstrated for the IEEE 118-bus power system, which is linked with the natural gas transmission system and the results are discussed in this paper.fi=vertaisarvioitu|en=peerReviewed

Electrical stimulation devices for the prevention of venous thromboembolism: Preliminary studies of physiological efficacy and user satisfaction.

Introduction: Electrical stimulation could provide an alternative method for preventing venous thromboembolism in stroke patients. The purpose of this preliminary study was to explore the effects of electrical stimulation and intermittent pneumatic compression on enhancing lower limb venous return in healthy and chronic stroke patients and also to evaluate patient and nurse satisfaction. Methods: We investigated the effectiveness of two electrical stimulation devices: Geko (Firstkind Ltd, High Wycombe, UK) and Orthopaedic Microstim 2V2 (Odstock Medical Ltd, Salisbury, UK); and one intermittent pneumatic compression device: Huntleigh Flowstron Universal (Huntleigh Healthcare Ltd, Cardiff, UK). We recruited 12 healthy and 5 chronic stroke participants. The devices were fitted sequentially, and Doppler ultrasound measurements were taken. Eight patients and nurses were also recruited for a separate usability evaluation. Results: The electrical stimulation devices emulated the blood flow characteristics of intermittent pneumatic compression in both healthy and stroke participants provided that the intensity of electrical stimulation was sufficient. Patients and nurses also felt that the electrical stimulation devices were acceptable. Conclusions: Electrical stimulation may offer benefit as an alternative method for venous thromboembolism prevention in stroke patients. The apparent benefit is sufficient to warrant further investigation in a full powered randomised controlled trial

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified

Impact of arteriovenous fistulas versus arteriovenous grafts on vascular access performance in haemodialysis patients: A systematic review and meta-analysis

BACKGROUND: Controversy exists regarding the best-performing vascular access type for patients undergoing haemodialysis. We aimed to compare outcomes of starting dialysis on arteriovenous fistulas (AVFs) versus arteriovenous grafts (AVGs) in haemodialysis patients. METHODS: We conducted a systematic search of multiple electronic information sources and bibliographic reference lists. The following outcome parameters were evaluated at 1, 2 and 5 years: primary failure, defined as access never used for dialysis; primary patency, defined as intervention-free access survival; primary-assisted patency, defined as uninterrupted access survival with interventions; and secondary patency, defined as cumulative access survival. RESULTS: We identified 15 comparative studies reporting a total of 118,434 patients who initiated haemodialysis with AVF (n = 95,143) or AVG (n = 23,291). Our analysis demonstrated that AVF was associated with significantly higher primary failure rate (OR: 2.05, p = .0005) but significantly higher rate of primary patency at 1 year (OR: 1.91, p < .00001), at 2 years (OR: 2.52, p < .00001) and at 5 years (OR: 2.59, p < .00001); and primary-assisted patency at 1 year (OR: 1.71, p < .00001), at 2 years (OR: 2.13, p < .00001) and 5 years (OR: 2.79, p < .00001). There was no significant difference in secondary patency at 1 year (OR: 1.08, p < .00001) but AVF had better secondary patency at 2 years (OR: 1.26, p < .00001) and 5 years (OR: 1.60, p < .00001) than AVG. CONCLUSIONS: The meta-analysis of best available comparative evidence (Level 2) demonstrated that AVFs may be associated with significantly higher primary failure rate but higher primary patency, primary-assisted patency and secondary patency at 1, 2 and 5 years compared to AVGs. However, the available evidence is subject to significant selection bias and confounding by indication.Not heldPublished version, accepted version, submitted versio

Treatment strategies for in-stent restenosis in peripheral arterial disease: a systematic review.

Our purpose was to investigate the outcomes of different treatment strategies for in-stent restenosis (ISR) in patients with peripheral arterial disease of the lower limbs

Sustainable development

© 2016, Springer International Publishing Switzerland. The continuous increase in the number and size of urban regions across the world pose great challenges for sustainable development. Given the connection between energy use, greenhouse gas emissions and climate change and the reality that the built environment emits around half of total emissions, the construction industry has considerable potential to reduce emissions and a key role in mitigating global warming. Other local challenges include for example loss of species and habitats, social degradation of neighborhoods, and an overall erosion of sustainability. Urbanisation patterns and the lifestyles of urban dwellers also affect the planet on wider scales and contribute to shaping bio-physical processes on planetary scales and affect how humans mentally connect with the Biosphere. However there is evidence our current understanding of the concept of sustainability, and thus sustainable development, is fragmented and unclear. There are a plethora of terms used to cover sustainable buildings, such as ecological, green, Gaian, zero energy, eco-friendly and environmental; all of which come in, and out, of fashion over time; do they mean the same thing or are they different? Furthermore, do the stakeholders within the built environment demonstrate a clear understanding of the concept of sustainability or; are they muddled and confused? The consequence of unclear thinking and a lack of understanding is that ultimately the built environment stakeholders are unlikely to deliver ‘sustainability’ efficiently or even at all, with the broader and more onerous consequences for society as a whole. In addition what are the implications for education and should academics be broadening the debate? This lecture examines the environmental, economic, social, political and philosophical thinking underpinning the concept of sustainable development and shows how different perspectives reflect very different ways of thinking about sustainability and sustainable development. It aims to create a better understanding while offering creative solutions