Objective functions with redundant domains

Let (E,A) be a set system consisting of a finite collection A of subsets of a ground set E, and suppose that we have a function ϕ which maps A into some set S. Now removing a subset K from E gives a restriction A(K¯) to those sets of A disjoint from K, and we have a corresponding restriction ϕ|A(K¯) of our function ϕ. If the removal of K does not affect the image set of ϕ, that is Im(ϕ|A(X¯))=Im(ϕ), then we will say that K is a kernel set of A with respect to ϕ. Such sets are potentially useful in optimisation problems defined in terms of ϕ. We will call the set of all subsets of E that are kernel sets with respect to ϕ a kernel system and denote it by Kerϕ(A). Motivated by the optimisation theme, we ask which kernel systems are matroids. For instance, if A is the collection of forests in a graph G with coloured edges and ϕ counts how many edges of each colour occurs in a forest then Kerϕ(A) is isomorphic to the disjoint sum of the cocycle matroids of the differently coloured subgraphs; on the other hand, if A is the power set of a set of positive integers, and ϕ is the function which takes the values 1 and 0 on subsets according to whether they are sum-free or not, then we show that Kerϕ(A) is essentially never a matroid

Caesarean section in Malawi: preventable factors in maternal and perinatal mortality.

OBJECTIVES: To examine factors that may influence maternal and perinatal mortality associated with caesarean section in an African country. DESIGN: A prospective observational study, conducted between January 1998 and June 2000, of 8070 caesarean sections. SETTING: 25 district and 2 central hospitals in Malawi. Main outcome measures. Association between hospital type, ward or operative care, training of surgical and anaesthesia personnel, preoperative complications, method of anaesthesia, blood loss and anaesthetic technique on maternal and perinatal mortality. RESULTS: Questionnaires were returned for 5236 caesarean sections in district and 2834 in central hospitals. 95% were emergencies, 65% for obstructed labour. Pre-operative haemorrhagic shock was present in 7.6% of women, anaemia in 6.2% and ruptured uterus in 4.1%. Previous caesarean section did not appear to predispose to ruptured uterus. There were 85 maternal deaths (1.05% mortality), 65 of which occurred postoperatively on the wards. Maternal mortality was increased with ruptured uterus (adjusted odds ratio 3.9, 95% CI 2.3-6.5), little anaesthetic training (2.3, 1.3 to 4.1) and blood loss requiring transfusion (19.3, 9-41). In mothers without preoperative haemorrhage spinal anaesthesia was associated with lower maternal mortality than general anaesthesia (0.23, 0.1-0.7). Perinatal mortality was 11.2% overall, and was significantly associated with ruptured uterus, halothane and ketamine anaesthesia. CONCLUSION: Maternal and perinatal mortality rates among women undergoing caesarean section in Malawi are high. Improving resuscitation in postoperative wards might reduce maternal mortality. Blood loss and pre-operative complications are both strongly associated with mortality. Spinal anaesthesia was associated with good outcome

Social trajectories or disrupted identities? : Changing and competing models of teacher professionalism under New Labour

Since the 1988 Education Reform Act, the teacher’s role in England has changed in many ways, a process which intensified under New Labour after 1997. Conceptions of teacher professionalism have become more structured and formalized, often heavily influenced by government policy objectives. Career paths have become more diverse and specialised. In this article, three post-1997 professional roles are given consideration as examples of these new specialised career paths: Higher Level Teaching Assistants, Teach First trainees and Advanced Skills Teachers. The article goes on to examine such developments within teaching, using Bourdieu’s concept of habitus to inform the analysis, as well as Bernstein’s theories of knowledge and identity. The article concludes that there has been considerable specialization and subsequent fragmentation of roles within the teaching profession, as part of workforce remodelling initiatives. However, there is still further scope for developing a greater sense of professional cohesion through social activism initiatives, such as the children's agenda. This may produce more stable professional identities in the future as the role of teachers within the wider children’s workforce is clarified

Geographical and temporal trends in imported infections from the tropics requiring inpatient care at the Hospital for Tropical Diseases, London - a 15 year study.

BACKGROUND: Understanding geographic and temporal trends in imported infections is key to the management of unwell travellers. Many tropical infections can be managed as outpatients, with admission reserved for severe cases. METHODS: We prospectively recorded the diagnosis and travel history of patients admitted between 2000 and 2015. We describe the common tropical and non-tropical infectious diseases and how these varied based on region, reason for travel and over time. RESULTS: A total of 4362 admissions followed an episode of travel. Falciparum malaria was the most common diagnosis (n=1089). Among individuals who travelled to Africa 1206/1724 (70.0%) had a tropical diagnosis. The risk of a tropical infection was higher among travellers visiting friends and relatives than holidaymakers (OR 2.8, p<0.001). Among travellers to Asia non-tropical infections were more common than tropical infections (349/782, 44.6%), but enteric fever (117, 33.5%) of the tropical infections and dengue (70, 20.1%) remained important. The number of patients admitted with falciparum malaria declined over the study but those of enteric fever and dengue did not. CONCLUSIONS: Most of those arriving from sub-Saharan Africa with an illness requiring admission have a classical tropical infection, and malaria still predominates. In contrast, fewer patients who travelled to Asia have a tropical diagnosis but enteric fever and dengue remain relatively common. Those visiting friends and relatives are most likely to have a tropical infection

Sound Diaries

Sound Diaries impacts through expanding awareness of the roles of sound and listening in daily life. The Sound Diaries website acts as a repository, sketchpad and sandpit for research promoting a principally auditory investigation of the world we live in. Exploring the cultural and communal significance of sounds, Sound Diaries forms a research basis for projects executed both locally and Internationally, in Beijing, Brussels, Tallinn, rural Estonia and Cumbria; within local institutions in Oxford including Schools; and within cultural organisations such as Sound and Music, BBC Radio, Boring 2011 and MoDA (Museum of Domestic Design and Architecture)

A Systematic Review Comparing the Acceptability, Validity and Concordance of Discrete Choice Experiments and Best–Worst Scaling for Eliciting Preferences in Healthcare

Objective: The aim of this study was to compare the acceptability, validity and concordance of discrete choice experiment (DCE) and best–worst scaling (BWS) stated preference approaches in health. Methods: A systematic search of EMBASE, Medline, AMED, PubMed, CINAHL, Cochrane Library and EconLit databases was undertaken in October to December 2016 without date restriction. Studies were included if they were published in English, presented empirical data related to the administration or findings of traditional format DCE and object-, profile- or multiprofile-case BWS, and were related to health. Study quality was assessed using the PREFS checklist. Results: Fourteen articles describing 12 studies were included, comparing DCE with profile-case BWS (9 studies), DCE and multiprofile-case BWS (1 study), and profile- and multiprofile-case BWS (2 studies). Although limited and inconsistent, the balance of evidence suggests that preferences derived from DCE and profile-case BWS may not be concordant, regardless of the decision context. Preferences estimated from DCE and multiprofile-case BWS may be concordant (single study). Profile- and multiprofile-case BWS appear more statistically efficient than DCE, but no evidence is available to suggest they have a greater response efficiency. Little evidence suggests superior validity for one format over another. Participant acceptability may favour DCE, which had a lower self-reported task difficulty and was preferred over profile-case BWS in a priority setting but not necessarily in other decision contexts. Conclusion: DCE and profile-case BWS may be of equal validity but give different preference estimates regardless of the health context; thus, they may be measuring different constructs. Therefore, choice between methods is likely to be based on normative considerations related to coherence with theoretical frameworks and on pragmatic considerations related to ease of data collection

Social prescribing programmes to prevent or delay frailty in community-dwelling older adults

The increasing incidence of frailty is a health and social care challenge. Social prescription is advocated as an important approach to allow health professionals to link patients with sources of support in the community. This study aimed to determine the current evidence on the effectiveness of social prescribing programmes to delay or reduce frailty in frail older adults living in the community. A systematic literature review of published (DARE, Cochrane Database of Systematic Reviews, MEDLINE, EMBASE, CINAHL, NICE and SCIE, NHS Economic Evaluation Database) and unpublished databases (OpenGrey; WHO Clinical Trial Registry; ClinicalTrials.gov) were searched to July 2019. Studies were eligible if they reported health, social or economic outcomes on social prescribing, community referral, referral schemes, wellbeing programmes or interventions when a non-health link worker was the intervention provider to people who are frail living in the community. 1079 unique studies were screened for eligibility. No papers were eligible. There is therefore a paucity of evidence reporting the effectiveness of social prescribing programmes for frail older adults living in the community. Given that frailty is a clinical priority and social prescribing is considered a key future direction in the provision of community care, this is a major limitation

Internet self-efficacy does not predict student use of Internet-mediated educational technology

Two studies tested the hypothesis that use of learning technologies among undergraduate psychology students was associated with higher Internet self-efficacy (ISE). In Study 1, the ISE scores of 86 students were found not to be associated with either attitudes towards, or measured use of, blogs and wikis as part of an IT skills course. ISE was associated with time spent online, and positive attitudes to wikis were associated with higher use. Study 2 measured 163 students’ ISE scores at the beginning and end of the same course. ISE was again not correlated with attitudes towards, or actual measured use of, learning technologies used in the course. However, ISE was shown to increase during the course. Positive attitudes towards wikis and discussion boards were associated with higher use of each. Overall, ISE scores did not influence measured use of a Virtual Learning Environment (VLE, including blogs, wikis and a discussion board), or attitudes towards those technologies. This implies that while ISE is linked to aspects of online behaviour (time spent online) and can be modified by online activity or training, it does not predict student use of educational Internet technologies

Recommendations from Two Citizens’ Juries on the Surgical Management of Obesity

Background: It is important that guidelines and criteria used to prioritise access to bariatric surgery are informed by the values of the tax-paying public in combination with the expertise of healthcare professionals. Citizens’ juries are increasingly used around the world to engage the public in healthcare decision-making. This study investigated citizens’ juries about prioritising patient access to bariatric surgery in two Australian cities. Objectives: The objective of this study is to examine public priorities for government expenditure on the surgical management of obesity developed through either a one or three-day citizen jury. Subjects/Methods: A three-day jury was held in Brisbane and a one-day jury in Adelaide. Jurors were selected in Brisbane (n = 18) and in Adelaide (n = 12) according to pre-specified criteria. Expert witnesses from various medical disciplines and consumers were cross-examined by jurors. Results: The verdicts of the juries were similar in that both juries agreed bariatric surgery was an important option in the management of obesity and related comorbidities. Recommendations about who should receive treatment differed slightly across the juries. Both juries rejected the use of age as a rationing tool, but managed their objections in different ways. Participants’ experiences of the jury process were positive, but our observations suggested that many variables may influence the nature of the final verdict. Conclusions: Citizen’s juries, even when shorter in duration, can be an effective tool to guide the development of health policy and priorities. However, our study has identified a range of variables that should be considered when designing and running a jury and when interpreting the verdict