Branch-and-lift algorithm for deterministic global optimization in nonlinear optimal control

This paper presents a branch-and-lift algorithm for solving optimal control problems with smooth nonlinear dynamics and potentially nonconvex objective and constraint functionals to guaranteed global optimality. This algorithm features a direct sequential method and builds upon a generic, spatial branch-and-bound algorithm. A new operation, called lifting, is introduced, which refines the control parameterization via a Gram-Schmidt orthogonalization process, while simultaneously eliminating control subregions that are either infeasible or that provably cannot contain any global optima. Conditions are given under which the image of the control parameterization error in the state space contracts exponentially as the parameterization order is increased, thereby making the lifting operation efficient. A computational technique based on ellipsoidal calculus is also developed that satisfies these conditions. The practical applicability of branch-and-lift is illustrated in a numerical example. © 2013 Springer Science+Business Media New York

Blogging Climate Change: A Case Study

Public perception of the magnitude of challenges associated with climate change is still lower than that of the majority of scientists. The societal relevance of climate change has raised the need for a more direct communication between scientists and the public. However, peer-reviewed scientific articles are not well-suited to engaging a wider audience. This begets a need to explore other avenues for communicating climate change. Social media is a vibrant source for information exchange among the masses. Blogs in particular are a promising tool for disseminating complex findings on topics such as climate change, as they are easier to comprehend and are targeted at a broader audience compared to scientific publications. This chapter discusses the usefulness of blogs in communicating climate change, using our blog Climate Footnotes (climatefootnotes.com) as a case study. Drawing from communication theory and our experiences with Climate Footnotes, we identify and describe elements such as message framing, translation of scientific data, role of language, and interactivity in aiding climate change communication. The insights outlined herein help understand the nature and impact of online climate change communication. The chapter may also serve as a useful blueprint for scientists interested in utilizing blogs to communicate climate change

Blogging Climate Change: A Case Study

Public perception of the magnitude of challenges associated with climate change is still lower than that of the majority of scientists. The societal relevance of climate change has raised the need for a more direct communication between scientists and the public. However, peer-reviewed scientific articles are not well-suited to engaging a wider audience. This begets a need to explore other avenues for communicating climate change. Social media is a vibrant source for information exchange among the masses. Blogs in particular are a promising tool for disseminating complex findings on topics such as climate change, as they are easier to comprehend and are targeted at a broader audience compared to scientific publications. This chapter discusses the usefulness of blogs in communicating climate change, using our blog Climate Footnotes (climatefootnotes.com) as a case study. Drawing from communication theory and our experiences with Climate Footnotes, we identify and describe elements such as message framing, translation of scientific data, role of language, and interactivity in aiding climate change communication. The insights outlined herein help understand the nature and impact of online climate change communication. The chapter may also serve as a useful blueprint for scientists interested in utilizing blogs to communicate climate change

Inter-individual variations of human mercury exposure biomarkers: a cross-sectional assessment

BACKGROUND: Biomarkers for mercury (Hg) exposure have frequently been used to assess exposure and risk in various groups of the general population. We have evaluated the most frequently used biomarkers and the physiology on which they are based, to explore the inter-individual variations and their suitability for exposure assessment. METHODS: Concentrations of total Hg (THg), inorganic Hg (IHg) and organic Hg (OHg, assumed to be methylmercury; MeHg) were determined in whole blood, red blood cells, plasma, hair and urine from Swedish men and women. An automated multiple injection cold vapour atomic fluorescence spectrophotometry analytical system for Hg analysis was developed, which provided high sensitivity, accuracy, and precision. The distribution of the various mercury forms in the different biological media was explored. RESULTS: About 90% of the mercury found in the red blood cells was in the form of MeHg with small inter-individual variations, and part of the IHg found in the red blood cells could be attributed to demethylated MeHg. THg in plasma was associated with both IHg and MeHg, with large inter-individual variations in the distribution between red blood cells and plasma. THg in hair reflects MeHg exposure at all exposure levels, and not IHg exposure. The small fraction of IHg in hair is most probably emanating from demethylated MeHg. The inter-individual variation in the blood to hair ratio was very large. The variability seemed to decrease with increasing OHg in blood, most probably due to more frequent fish consumption and thereby blood concentrations approaching steady state. THg in urine reflected IHg exposure, also at very low IHg exposure levels. CONCLUSION: The use of THg concentration in whole blood as a proxy for MeHg exposure will give rise to an overestimation of the MeHg exposure depending on the degree of IHg exposure, why speciation of mercury forms is needed. THg in RBC and hair are suitable proxies for MeHg exposure. Using THg concentration in plasma as a measure of IHg exposure can lead to significant exposure misclassification. THg in urine is a suitable proxy for IHg exposure

General practitioners' attitudes and preparedness towards Clinical Decision Support in e-Prescribing (CDS-eP) adoption in the West of Ireland: a cross sectional study

Background: Electronic clinical decision support (CDS) is increasingly establishing its role in evidence-based clinical practice. Considerable evidence supports its enhancement of efficiency in e-Prescribing, but some controversy remains. This study evaluated the practicality and identified the perceived benefits of, and barriers to, its future adoption in the West of Ireland. Methods: This cross sectional study was carried out by means of a 27-part questionnaire sent to 262 registered general practitioners in Counties Galway, Mayo and Roscommon. The survey domains encompassed general information of individual's practice, current use of CDS and the practitioner's attitudes towards adoption of CDS-eP. Descriptive and inferential analyses were performed to analyse the data collected. Results: The overall response rate was 37%. Nearly 92% of respondents employed electronic medical records in their practice. The majority acknowledged the value of electronic CDS in improving prescribing quality (71%) and reducing prescribing errors (84%). Despite a high degree of unfamiliarity (73%), the practitioners were open to the use of CDS-eP (94%) and willing to invest greater resources for its implementation (62%). Lack of a strategic implementation plan (78%) is the main perceived barrier to the incorporation of CDS-eP into clinical practice, followed by i) lack of financial incentives (70%), ii) lack of standardized product software (61%), iii) high sensitivity of drug-drug interaction or medication allergy markers (46%), iv) concern about overriding physicians' prescribing decisions(44%) and v) lack of convincing evidence on the systems' effectiveness (22%). Conclusions: Despite favourable attitudes towards the adoption of CDS-eP, multiple perceived barriers impede its incorporation into clinical practice. These merit further exploration, taking into consideration the structure of the Irish primary health care system, before CDS-eP can be recommended for routine clinical use in the West of Ireland.Healthcare Informatics Society of Ireland (HISI) research bursary 2007-2009Deposited by bulk impor

How managed a market? Modes of commissioning in England and Germany

Background: In quasi-markets governance over healthcare providers is mediated by commissioners. Different commissioners apply different combinations of six methods of control (’media of power’) for exercising governance: managerial performance, negotiation, discursive control, incentives, competition and juridical control. This paper compares how English and German healthcare commissioners do so. Methods: Systematic comparison of observational national-level case studies in terms of six media of power, using data from multiple sources. Results: The comparison exposes and contrasts two basic generic modes of commissioning: 1. Surrogate planning (English NHS), in which a negotiated order involving micro-commissioning, provider competition, financial incentives and penalties are the dominant media of commissioner power over providers. 2. Case-mix commissioning (Germany), in which managerial performance, an ‘episode based’ negotiated order and juridical controls appear the dominant media of commissioner power. Conclusions: Governments do not necessarily maximise commissioners’ power over providers by implementing as many media of power as possible because these media interact, some complementing and others inhibiting each other. In particular, patient choice of provider inhibits commissioners’ use of provider competition as a means of control