A quantum-dot heat engine operating close to the thermodynamic efficiency limits

Cyclical heat engines are a paradigm of classical thermodynamics, but are impractical for miniaturization because they rely on moving parts. A more recent concept is particle-exchange (PE) heat engines, which uses energy filtering to control a thermally driven particle flow between two heat reservoirs. As they do not require moving parts and can be realized in solid-state materials, they are suitable for low-power applications and miniaturization. It was predicted that PE engines could reach the same thermodynamically ideal efficiency limits as those accessible to cyclical engines, but this prediction has not been verified experimentally. Here, we demonstrate a PE heat engine based on a quantum dot (QD) embedded into a semiconductor nanowire. We directly measure the engine's steady-state electric power output and combine it with the calculated electronic heat flow to determine the electronic efficiency $\eta$. We find that at the maximum power conditions, $\eta$ is in agreement with the Curzon-Ahlborn efficiency and that the overall maximum $\eta$ is in excess of 70$\%$ of the Carnot efficiency while maintaining a finite power output. Our results demonstrate that thermoelectric power conversion can, in principle, be achieved close to the thermodynamic limits, with direct relevance for future hot-carrier photovoltaics, on-chip coolers or energy harvesters for quantum technologies

Informal Caregivers' Experiences and Needs When Caring for a Relative With Heart Failure: An Interview Study

Background: Informal caregivers play an important role for persons with heart failure in strengthening medication adherence, encouraging self-care, and identifying deterioration in health status. Caring for a relative with heart failure can affect informal caregivers' well-being and cause caregiver burden. Objective: The objective of this study was to explore informal caregivers' experiences and needs when caring for a relative with heart failure living in their own home. Methods: The study has a qualitative design with an inductive approach. Interviews were conducted with 14 informal caregivers. Data were analyzed using qualitative content analysis. Results: Two themes emerged: "living in a changed existence" and "struggling and sharing with healthcare." The first theme describes informal caregivers' experiences, needs, and ways of moving forward when living in a changed existence with their relative. Informal caregivers were responsible for the functioning of everyday life, which challenged earlier established roles and lifestyle. They experienced an ever-present uncertainty related to the relative's impending sudden deterioration and to lack of knowledge about the condition. Incongruence was expressed between their own and their relative's understanding and acceptance of the heart failure condition. They also expressed being at peace with their relative and managed to restore new strength and motivation to care. The second theme describes informal caregivers' experiences, needs, and ways in which they handled the healthcare. They felt counted upon but not accounted for, as their care was taken for granted while their need to be seen and acknowledged by healthcare professionals was not met. Informal caregivers experienced an ever-present uncertainty regarding their lack of involvement with healthcare. The lack of involvement with healthcare had a negative impact on the relationship between informal caregivers and their relative due to the mutual loss of important information about changes in medication regimens and the relative's symptoms and well-being. Another cause of negative impact was the lack of opportunity to talk with healthcare professionals about the emotional and relational consequences of heart failure. Healthcare professionals had provided them neither with knowledge on heart failure nor with information on support groups in the municipality. Informal caregivers captured their own mandate through acting as deputies for their relative and claiming their rights of involvement in their relative's healthcare. They also felt confident despite difficult circumstances. The direct access to the medical clinic was a source of relief and they appreciated the contacts with the registered nurses specialized in heart failure. Informal caregivers' own initiatives to participate in meetings were positively received by healthcare professionals. Conclusions: Informal caregivers' daily life involves decisive changes that are experienced as burdensome. They handled their new situations using different strategies to preserve a sense of "self" and of "us." Informal caregivers express a need for more involvement with healthcare professionals, which may facilitate informal caregivers' situation and improve the dyadic congruence in the relation with their relative

Coronary heart disease and risk factors as predictors of trajectories of psychological distress from midlife to old age.

OBJECTIVE: To examine coronary heart disease (CHD) and its risk factors as predictors of long-term trajectories of psychological distress from midlife to old age. METHODS: In the Whitehall II cohort study, 6890 participants (4814 men, 2076 women; mean age 49.5 years) had up to seven repeat assessments of psychological distress over 21 years (mean follow-up 19 years). CHD and its risk factors (lifestyle-related risk factors, diabetes, hypertension and cholesterol) were assessed at baseline. Group-based trajectory modelling was used to identify clusters of individuals with a similar pattern of psychological distress over time. RESULTS: We identified four trajectories of psychological distress over the follow-up: 'persistently low' (69% of the participants), 'persistently intermediate' (13%), 'intermediate to low' (12%) and 'persistently high' (7%). The corresponding proportions were 60%, 16%, 13% and 11% among participants with CHD; 63%, 15%, 12% and 10% among smokers and 63%, 16%, 12% and 10% among obese participants. In multivariable adjusted multinomial regression analyses comparing other trajectories to persistently low trajectory, prevalent CHD was associated with intermediate to low (OR 1.70, 95% CI 1.08 to 2.68) and persistently high (OR 1.92, 95% CI 1.16 to 3.19) trajectories. Smoking (OR 1.33, 95% CI 1.07 to 1.64; OR 1.55, 95% CI 1.19 to 2.04) and obesity (OR 1.33, 95% CI 1.04 to 1.70; OR 1.47, 95% CI 1.07 to 2.01) were associated with persistently intermediate and persistently high trajectories, respectively. CONCLUSION: CHD, smoking and obesity may have a role in the development of long-lasting psychological distress from midlife to old age

Operationalisation of ecological compensation - Obstacles and ways forward

Ecological compensation (EC) has been proposed as an important tool for stopping the loss of biodiversity and natural values. However, there are few studies on its actual operationalisation and there is high uncertainty about how it should be designed and implemented to be an effective way of performing nature conservation. In this study we focus on ecological compensation in Sweden, a country where it is in the process of being implemented more broadly. Using interviews and a workshop we investigate how the work with the implementation is carried out and what challenges exist. The results show that implementation of EC is at an early stage of development and there are many practical obstacles, linked to both legislation and routines in the planning processes. There is a lack of holistic perspective and large-scale thinking, a quite strong focus on a small number of individual species, and an overall attitude that anything is better than nothing, all of which can have negative consequences for biodiversity conservation overall. Based on the results we discuss the need for better integration of EC into the entire decision-making process and for a holistic approach to preservation of biodiversity and ecosystem services, by increasing the focus on landscape perspective and considering delays in compensation outcomes. There is also a need for a national level standard for EC, making good and worse examples of compensation measures available and systematic monitoring of EC projects. Finally, a spatially explicit database to document all EC areas should be introduced both to ensure consistency in protection from future development plans and to enable long-term monitoring of EC outcomes

Guidelines (1988) for training in clinical laboratory management

Trainees in laboratory medicine must develop skills in laboratory management. Guidelines are detailed for laboratory staff in training, directors responsible for staff development and professional bodies wishing to generate material appropriate to their needs. The syllabus delineates the knowledge base required and includes laboratory planning and organization, control of operations, methodology and instrumentation, data management and statistics, financial management, clinical use of tests, communication, personnel management and training and research and development. Methods for achievement of the skills required are suggested. A bibliography of IFCC publications and other material is provided to assist in training in laboratory management

On the Price of Anarchy of Highly Congested Nonatomic Network Games

We consider nonatomic network games with one source and one destination. We examine the asymptotic behavior of the price of anarchy as the inflow increases. In accordance with some empirical observations, we show that, under suitable conditions, the price of anarchy is asymptotic to one. We show with some counterexamples that this is not always the case. The counterexamples occur in very simple parallel graphs.Comment: 26 pages, 6 figure

Network analysis through the use of Joint-Distribution Entropy on EEG recordings of MCI Patients during a visual short-term memory binding task

The early diagnosis of Alzheimer's disease (AD) is particularly challenging. Mild cognitive impairment (MCI) has been linked to AD and electroencephalogram (EEG) recordings are able to measure brain activity directly with high temporal resolution. In this context, with appropriate processing, the EEG recordings can be used to construct a graph representative of brain functional connectivity. This work studies a functional network created from a non-linear measure of coupling of beta-filtered EEG recordings during a short-term memory binding task. It shows that the values of the small-world characteristic and eccentricity are, respectively, lower and higher in MCI patients than in controls. The results show how MCI leads to EEG functional connectivity changes. They expect that the network differences between MCIs and control subjects could be used to gain insight into the early stages of AD

Oesophageal symptoms are common and associated with other functional gastrointestinal disorders (FGIDs) in an English-speaking Western population

mean age 46.7 years) were available for analysis. Symptom prevalence was 8.1% for globus, 6.5% for heartburn, 4.5% for dysphagia and 5.2% for chest pain, and 17.0% reported at least one oesophageal symptom. Oesophageal symptoms were independently associated with younger age, female gender, previous abdominal surgery and the presence of other functional GI disorders. Reporting oesophageal symptoms was associated with reduced quality of life. Conclusion: Oesophageal symptoms are common in the general population and important predictors include other functional GI disorders, age and gender. Oesophageal symptoms are associated with poorer quality of life.Background: The prevalence and frequency of oesophageal symptoms suggestive of a functional oesophageal disorder according to the Rome IV criteria are unknown. Objective: We aimed to describe the prevalence and risk factors for oesophageal symptoms compatible with functional oesophageal disorders in the general population. Methods: Data were analysed from a population-based online survey of 6300 individuals aged ≥ 18 years in the USA, UK and Canada with equal demographic proportions across countries. Questions included the Rome IV diagnostic questionnaire, demographics, medication, somatization, quality of life, and organic gastrointestinal (GI) disease. Multivariate analysis was used to identify factors independently related to oesophageal symptoms. Results: Data from 5177 participants (47.8% femal

Starting the conversation: land issues and critical conservation studies in post-colonial Africa

This thematic issue brings together the scholarly fields of critical conservation studies and African land issues, a relationship largely unexplored to date. The alienation of land for conservation purposes, introduced to Africa under colonial rule and still taking place today, has fundamental impacts on the politics of land and land use, and is contested in contemporary nation-states - including those that are attempting to implement land restitution and reform. The contributors explore these issues in a range of African contexts. Three key themes are identified: the problematic constructions of ‘community’ by outside agencies; spatial exclusion and the silencing of local voices; and the neoliberalisation of conservation spaces. In contributing to new perspectives on these themes, this thematic issue shows how discourses and practices of conservation, increasingly shaped by neoliberalism, currently impact on land ownership, access and use. It further highlights some important historical continuities. These trends can be observed in transfrontier conservation areas, on state-owned land used for conservation and ‘green’ initiatives, but also on private land where conservation is increasingly turned to commercial purposes.International Bibliography of Social Science