Line

Review of Line: A group exhibition at the Lisson Gallery, London. 22 January - 12 March 2016. Curated by: Mary Doyle and Kate Macfarlane

Irreversibility Measures in a Quantum Setting

A satisfactory understanding of macroscopic irreversibility has remained elusive since the advent of thermodynamics. Progress has nevertheless been made in understanding irreversibility measures classically; this work explores irreversibility in a quantum setting. Entropy production quantifies the irreversibility associated with open stochastic dynamical systems, and our main aim has been to extend this concept. Understanding the thermodynamics of open quantum systems better will eventually improve the efficiency of increasingly feasible nanoscale operations. An exact method to model the thermodynamic properties of open quantum systems is the stochastic Liouville-von Neumann (SLN) equation, based on unravelling Feynman-Vernon influence functionals. We extend its use from the one heat bath case to a system in a non-equilibrium stationary state due to coupling to more than one heat bath. An asymmetry in the probabilistic specification of a closed deterministic system can lead to a disparity between the likelihoods of a particular forward and corresponding backward behaviour starting from a specified time. Such a comparison is a test of a property denoted obversibility, quantified in terms of dissipation production – rather than entropy production – as a measure of irreversibility. We evaluate dissipation production in a deterministic two-level quantum system described by a statistical ensemble of state vectors. We identify the conditions under which the dissipation production fulfills an Evans-Searles Fluctuation Theorem and for which the system will display time-asymmetric average behaviour as it evolves. Finally, we use a Kraus operator formalism to present a minimal model for the random evolution in the Bloch sphere of individual trajectory realisations of the coherence vector of a qubit and use it to evaluate the entropy production associated with weak quantum measurement, with both one and two measurement operators, before speculating on the consequences of our results to our understanding of quantum measurement and the associated indeterminism

Selenium supplementation for the primary prevention of cardiovascular disease

Background: Selenium is a key component of a number of selenoproteins which protect against oxidative stress and have the potential to prevent chronic diseases including cardiovascular disease (CVD). However, observational studies have shown inconsistent associations between selenium intake and CVD risk; in addition, there is concern around a possible increased risk of type 2 diabetes with high selenium exposure. Objectives: To determine the effectiveness of selenium only supplementation for the primary prevention of CVD and examine the potential adverse effect of type 2 diabetes. Search methods: The following electronic databases were searched: the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 10 of 12, October 2012) on The Cochrane Library; MEDLINE (Ovid) (1946 to week 2 October 2012); EMBASE Classic + EMBASE (Ovid) (1947 to 2012 Week 42); CINAHL (EBSCO) (to 24 October 2012); ISI Web of Science (1970 to 24 October 2012); PsycINFO (Ovid) (1806 to week 3 October 2012); Database of Abstracts of Reviews of Effects (DARE), Health Technology Assessment Database and Health Economics Evaluations Database (Issue 4 of 4, October 2012) on The Cochrane Library. Trial registers and reference lists of reviews and articles were searched and experts in the field were approached. No language restrictions were applied. Selection criteria: Randomised controlled trials on the effects of selenium only supplementation on major CVD end-points, mortality, changes in CVD risk factors, and type 2 diabetes were included both in adults of all ages from the general population and in those at high risk of CVD. Trials were only considered where the comparison group was placebo or no intervention. Only studies with at least three months follow-up were included in the meta-analyses, shorter term studies were dealt with descriptively. Data collection and analysis: Two review authors independently assessed trial quality and extracted data. Study authors were contacted for additional information. Main results: Twelve trials (seven with duration of at least three months) met the inclusion criteria, with 19,715 participants randomised. The two largest trials that were conducted in the USA (SELECT and NPC) reported clinical events. There were no statistically significant effects of selenium supplementation on all cause mortality (RR 0.97, 95% CI 0.88 to 1.08), CVD mortality (RR 0.97, 95% CI 0.79 to 1.2), non-fatal CVD events (RR 0.96, 95% CI 0.89 to 1.04) or all CVD events (fatal and non-fatal) (RR 1.03, 95% CI 0.95 to 1.11). There was a small increased risk of type 2 diabetes with selenium supplementation but this did not reach statistical significance (RR 1.06, 95% CI 0.97 to 1.15). Other adverse effects that increased with selenium supplementation, as reported in the SELECT trial, included alopecia (RR 1.28, 95% CI 1.01 to 1.62) and dermatitis grade 1 to 2 (RR 1.17, 95% CI 1.0 to 1.35). Selenium supplementation reduced total cholesterol but this did not reach statistical significance (WMD - 0.11 mmol/L, 95% CI - 0.3 to 0.07). Mean high density lipoprotein (HDL) levels were unchanged. There was a statistically significant reduction in non-HDL cholesterol (WMD - 0.2 mmol/ L, 95% CI - 0.41 to 0.00) in one trial of varying selenium dosage. None of the longer term trials examined effects on blood pressure. Overall, the included studies were regarded as at low risk of bias. Authors’ conclusions: The limited trial evidence that is available to date does not support the use of selenium supplements in the primary prevention of CVD

'Mediterranean' dietary pattern for the primary prevention of cardiovascular disease

It is well established that diet plays a major role in cardiovascular disease risk. The traditional Mediterranean dietary pattern is of particular interest because of observations from the 1960s that populations in countries of the Mediterranean region, such as Greece and Italy, had lower mortality from cardiovascular disease compared with northern European populations or the US, probably as a result of different eating habits. This review assessed the effects of providing dietary advice to follow a Mediterranean-style dietary pattern to healthy adults or people at increased risk of cardiovascular disease in order to prevent the occurrence of cardiovascular disease and reduce the risk factors associated with it. Definitions of a Mediterranean dietary pattern vary and we included only randomised controlled trials (RCTs) of interventions that reported at least two of the following components: (1) high monounsaturated/saturated fat ratio, (2) low to moderate red wine consumption, (3) high consumption of legumes, (4) high consumption of grains and cereals, (5) high consumption of fruits and vegetables, (6) low consumption of meat and meat products and increased consumption of fish, and (7) moderate consumption of milk and dairy products. The control group was no intervention or minimal intervention. We found 11 RCTs (15 papers) that met these criteria. The trials varied enormously in the participants recruited and the different dietary interventions. Four trials were conducted in women only, two trials were in men only and the remaining five were in both men and women. Five trials were conducted in healthy individuals and six trials were in people at increased risk of cardiovascular disease or cancer. The number of components relevant to a Mediterranean dietary pattern ranged from two to five and only seven trials described the intervention as a Mediterranean diet. The largest trial, which recruited only postmenopausal women and was not described as a Mediterranean diet meeting only two of the criteria described above, reported no difference in the occurrence of cardiovascular disease between the dietary advice group and the control group. The other trials measured risk factors for cardiovascular disease. As the studies were so different, it was not possible to combine studies for most of the outcomes. Where it was possible to combine studies, we found small reductions in total cholesterol levels as well as in the harmful low-density lipoprotein (LDL) cholesterol concentrations. The reductions in total cholesterol were greater in the studies that described themselves as providing a Mediterranean diet. None of the trials reported side effects. The review concludes that, from the limited evidence to date, a Mediterranean dietary pattern reduces some cardiovascular risk factors. However, more trials are needed to look at the effects of the different participants recruited and the different dietary interventions to see which interventions might work best in different populations

Resilience in older people living with dementia – A narrative analysis

Dominant discourses surrounding dementia tend to focus on narratives of loss and decline. Simultaneously, individuals living with dementia are vulnerable to being dispossessed of personal narratives supportive of identity and well-being. How older people with dementia story their experiences of resilience in this context has not previously been investigated. In response, this qualitative study utilised a narrative approach to understand lived experiences of resilience shared by eight older people living with dementia. Structural analyses indicated that participants’ personal narratives regarding resilience in living with dementia contained distinct and common phases (The Diagnosis, Initial Tasks, 'The High Point', Reflecting on Limitations and Focusing on Today) as well as a variety of dynamic characters. Overarching themes within participants’ narratives included sense of self/identity, being connected to others, sense of agency and having positive attitudes. Participants narrated richer, more active personal stories than those typically represented in dominant social discourses surrounding dementia. As such, their narratives depict lived experiences of resilience that unfolded over time in response to adversity and uncertainty and involved a dialectical process in relation to adjustment and well-being. The findings have important implications for the way resilience in living with dementia is framed and supported

Changing Work Systems, Changing Social Relations? A Canadian General Motors Plant

Cet article présente quelques conclusions tirées d'une étude ethnographique portant sur les relations sociales dans une entreprise d'assemblage de véhicules où la chaîne traditionnelle fut remplacée par une technologie suédoise automatisée et où quelques aspects de l'organisation japonaise du travail furent implantés. Cette usine de General Motors à Oshawa (Ontario) est intéressante en ce que non seulement y trouve-t-on une approche hybride de deux modèles de travail mais en plus y retrouve-t-on une main-d’œuvre qui était en grande partie la même avant et après ces changements.Le syndicat des Travailleurs canadiens de l'automobile (TCA) regroupent ces employés et le comité d'atelier a traditionnellement eu une réputation de militantisme relatif. Nos conclusions remettent en question l'idée que le fordisme est en train d'être supplanté par un nouveau modèle de production résultant dans un travail plus satisfaisant et dans des relations sociales plus coopératives.Résumons de la façon suivante les relations en milieu de travail durant les premiers dix-huit mois d'opération. Les travailleurs ont apprécié de façon presque unanime d'une part le nouvel environnement de travail amélioré par la technologie et, d'autre part l'engagement de la direction envers la qualité. Une promesse de départ s'est cependant vite dissipée vu l'intensification du travail sous le nouveau système et suite au recours par la direction à des tactiques traditionnelles pour assurer la production. En est résulté une période de relations hautement contradictoires entre négociations, discipline et efforts pour atteindre et même dépasser les objectifs de production. Cette tourmente fut suivie par un accommodement stabilisant les relations, maintenant caractérisées par une acceptation pragmatique du fordisme plutôt que par l'engagement prévu par les tenants des modèles post-fordistes.L'analyse de ces dynamiques d'atelier démontre que même si plusieurs perspectives théoriques apportent certains éléments pertinents, aucune n'explique la complexité des rapports sociaux de travail. La nouvelle technologie a eu des effets indépendants sur l'expérience de travail, positifs et négatifs, mais n'a pas déterminé pas les relations de travail. Tant le modèle de choix stratégique que la théorie sur le procès de travail n'ont pu expliquer pourquoi la direction a eu recours à des tactiques coercitives inspirées d'éléments motivationnels du nouveau système de travail. Les problèmes d'implantation sont certes inévitables, mais ils ne constituent aucunement une explication suffisante.Notre propre explication emprunte de l'approche axée sur la production du consentement (Edwards 1986 ; Bélanger, Edwards and Haiven 1994). Plus spécifiquement, il y a contradiction entre contrôle et consentement : la présence accrue de contrôle, surtout de type coercitif va entraîner la résistance des travailleurs. Cependant, un contrôle moindre ou insuffisant peut résulter en une productivité et une qualité en deçà des normes acceptables. Le résultat en est que la négociation, le conflit et la coopération sont au cœur même du travail et n'apparaissent aucunement comme un accident de parcours. Il faut donc que cette contradiction soit amenuisée ou éliminée pour que l'engagement et des relations consensuelles prédominent. Nos résultats, suite à l'études de cette usine et de d'autres lieux de travail, suggèrent plutôt que la contradiction entre contrôle et consentement a été exagérée au sujet des systèmes fordistes. Un thème commun est cependant celui de la désillusion des travailleurs face à ces nouveaux systèmes de travail suite aux différences entre les promesses et les résultats vécus. Nous explorons les aspects matérialistes et subjectifs des tensions ainsi créées. Plus la gérance stimule les intérêts de production des travailleurs afin d'atteindre le consentement, plus il y a de risques qu'il y ait efforts subséquents de la gérance de contrôler la production seulement selon sa propre logique. Il faut donc conclure que la situation actuelle, tant au niveau macro que micro, ne présage aucunement un abandon significatif des relations fordistes de production.This article presents some findings of an ethnographic case study on social relations in an existing vehicle assembly plant where the traditional drag chain has been replaced by Swedish automated guided vehicle technology and some aspects of Japanese work organization have been implemented. The findings challenge claims that Fordism is being replaced by a fundamentally new production model, and that this is resulting in more fulfilling work and cooperative social relations. There are many continuities with Fordism and highly contradictory social relations. This and other studies of new work Systems suggest, in fact, that contradictions between control and commitment, rather than being minimized or dissolved, can actually be heightened.Este articulo présenta algunos resultados de un estudio etnogràfico sobre las relaciones sociales en una planta de asamblaje automotriz que cambio de un estilo de producciòn clàsico con una cadena continua de producciòn a una tecnologìa sueca de direcciòn automàtica del vehiculo combinada con la implementaciòn de algunos aspectos de la organizaciòn del trabajo japonés. Los resultados contradicen la creencia que el Fordismo esta siendo desplazado por un fundamentalmente nuevo modelo de producciòn, y que este cambio a resultado en un clima de trabajo mas reconfortante y un cambio en las relaciones sociales cooperativas. Este y otros estudios de los nuevos sistemas de producciòn sugieren, de hecho, que las contradicciones entre el control y el compromiso, en lugar de ser minimizadas o completamente eliminadas, estàn siendo subrayadas

Proof of principle : the adaptive geometry of social foragers

Acknowledgments We thank Cape Nature for permission to undertake the study. We thank Dr Matt Grove and two anonymous referees for comments and suggestions that improved the manuscript substantially. This research was funded by grants from the Leakey Foundation, National Science and Engineering Research Council, Canada to S.P.H. and L.B., and by the National Research Foundation, South Africa to S.P.H. His co-authors dedicate this paper to the memory of P.M.R.C. The authors declare no competing interests.Peer reviewedPostprin