Electron transport in the dye sensitized nanocrystalline cell

Dye sensitised nanocrystalline solar cells (Gr\"{a}tzel cells) have achieved solar-to-electrical energy conversion efficiencies of 12% in diffuse daylight. The cell is based on a thin film of dye-sensitised nanocrystalline TiO$_2$ interpenetrated by a redox electrolyte. The high surface area of the TiO$_2$ and the spectral characteristics of the dye allow the device to harvest 46% of the solar energy flux. One of the puzzling features of dye-sensitised nano-crystalline solar cells is the slow electron transport in the titanium dioxide phase. The available experimental evidence as well as theoretical considerations suggest that the driving force for electron collection at the substrate contact arises primarily from the concentration gradient, ie the contribution of drift is negligible. The transport of electrons has been characterised by small amplitude pulse or intensity modulated illumination. Here, we show how the transport of electrons in the Gr\"{a}tzel cell can be described quantitatively using trap distributions obtained from a novel charge extraction method with a one-dimensional model based on solving the continuity equation for the electron density. For the first time in such a model, a back reaction with the I$_3^-$ ions in the electrolyte that is second order in the electron density has been included.Comment: 6 pages, 5 figures, invited talk at the workshop 'Nanostructures in Photovoltaics' to appear in Physica

A framework to explore the functioning and sustainability of business models

This paper presents a framework to enable case study analysis of sustainable development from business models innovation. Increasing economic development can give rise to trade-offs between economic growth and environmental degradation. Business model innovation can help address such trade-offs by refocusing value creation and capture towards less environmentally damaging activities. Business models therefore provide a critical tool in the move towards sustainable development. In this paper a literature review of existing business model frameworks is conducted and gaps found in the definition and conceptualisation of value, alignment with sustainable development, and assessment of social and environmental impacts and goals. More generally, there is a lack of in depth case studies in the sustainable business model literature. A framework is developed to address these gaps and to allow in depth analysis and understanding of the functioning of business models for sustainable development. Development and piloting of the framework made use of literature and co-operative enquiry. The framework of the paper is applied in depth with a unique energy company case study. Application shows economies of scope to be critical to the delivery of sustainable development. The business model framework addresses equity and distributional issues that are key to sustainable development, but missed by current frameworks

Assessing citizen science participation skill for altruism or university course credit: a case study analysis

peer-reviewedA common challenge in citizen science projects is gaining and retaining participants. At the same time, the tertiary education sector is constantly being challenged to provide more meaningful and practical work for students. Can participation in citizen science projects be used as coursework with real practical experiential-learning benefits, without affecting the citizen science project outcomes? We seek to begin to answer this question via a case study analysis with Cyclone Center (CC), which asks participants to classify tropical cyclone characteristics through analysis of infrared satellite imagery. Skill of individual users has previously been shown to be obtainable once classifiers have looked at approximately 200 images using an expectation-maximisation likelihood approach. We use skill scores to determine if participation for course credit or altruism influenced skill for volunteers and students from two universities under three increasingly complex categories of classifications (eye or no eye; stronger, weaker, or the same; and which of six fundamental storm types). A bootstrap resampling approach was used to account for discrepancies between sample sizes. Overall, there is limited evidence for substantive differences in classification performance between credit awarded and altruistic participants, with only one finding of significance at <p = 0.05 (Maynooth University showing lower mean agreement with the volunteer consensus on eye vs. no-eye). There is evidence that integrating participation into a larger assessment that requires the students to show understanding of the project may reduce a low-skill student tail. Furthermore, students’ perceptions of the coursework compared to more traditional assignments were overall favourable. These findings, if replicated for other citizen science projects, open up possible avenues to more generally increasing participation in, and exploitation of, citizen science projects in the academic secto

A European training system in cardiothoracic surgery: is it time?

OBJECTIVE Training in cardiothoracic surgery across Europe remains diverse and variable despite the ever closer integration of European countries at all levels and in all areas of life. Coupled with the increasing ease of movement across Europe, the need for uniform training programmes has arisen to allow for equivalent accreditation and certification. METHODS We review the current training paradigms within the specialty across the world and in Europe and also explore the concept of competence. RESULTS There are diverse training systems across the world and in Europe in particular. Competence-based training is the new model of training; however, competence remains difficult to define and measure. We propose a European Training Programme in Cardiothoracic Surgery that aims to standardize training across the European countries. CONCLUSIONS The difficulties in unifying training across Europe are numerous, but it is time to implement a European Training System in Cardiothoracic Surgery that will deliver a competence-based curriculu

Up-Regulation and Profibrotic Role of Osteopontin in Human Idiopathic Pulmonary Fibrosis

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a progressive and lethal disorder characterized by fibroproliferation and excessive accumulation of extracellular matrix in the lung. METHODS AND FINDINGS: Using oligonucleotide arrays, we identified osteopontin as one of the genes that significantly distinguishes IPF from normal lungs. Osteopontin was localized to alveolar epithelial cells in IPF lungs and was also significantly elevated in bronchoalveolar lavage from IPF patients. To study the fibrosis-relevant effects of osteopontin we stimulated primary human lung fibroblasts and alveolar epithelial cells (A549) with recombinant osteopontin. Osteopontin induced a significant increase of migration and proliferation in both fibroblasts and epithelial cells. Epithelial growth was inhibited by the pentapeptide Gly-Arg-Gly-Asp-Ser (GRGDS) and antibody to CD44, while fibroproliferation was inhibited by GRGDS and antibody to α(v)β(3) integrin. Fibroblast and epithelial cell migration were inhibited by GRGDS, anti-CD44, and anti-α(v)β(3). In fibroblasts, osteopontin up-regulated tissue inhibitor of metalloprotease-1 and type I collagen, and down-regulated matrix metalloprotease-1 (MMP-1) expression, while in A549 cells it caused up-regulation of MMP-7. In human IPF lungs, osteopontin colocalized with MMP-7 in alveolar epithelial cells, and application of weakest link statistical models to microarray data suggested a significant interaction between osteopontin and MMP-7. CONCLUSIONS: Our results provide a potential mechanism by which osteopontin secreted from the alveolar epithelium may exert a profibrotic effect in IPF lungs and highlight osteopontin as a potential target for therapeutic intervention in this incurable disease

Diagnostic Accuracy of Prion Disease Biomarkers in Iatrogenic Creutzfeldt-Jakob Disease

Human prion diseases are classified into sporadic, genetic, and acquired forms. Within this last group, iatrogenic Creutzfeldt-Jakob disease (iCJD) is caused by human-to-human transmission through surgical and medical procedures. After reaching an incidence peak in the 1990s, it is believed that the iCJD historical period is probably coming to an end, thanks to lessons learnt from past infection sources that promoted new prion prevention and decontamination protocols. At this point, we sought to characterise the biomarker profile of iCJD and compare it to that of sporadic CJD (sCJD) for determining the value of available diagnostic tools in promptly recognising iCJD cases. To that end, we collected 23 iCJD samples from seven national CJD surveillance centres and analysed the electroencephalogram and neuroimaging data together with a panel of seven CSF biomarkers: 14-3-3, total tau, phosphorylated/total tau ratio, alpha-synuclein, neurofilament light, YKL-40, and real-time quaking induced conversion of prion protein. Using the cut-off values established for sCJD, we found the sensitivities of these biomarkers for iCJD to be similar to those described for sCJD. Given the limited relevant information on this issue to date, the present study validates the use of current sCJD biomarkers for the diagnosis of future iCJD cases.This research was funded by the Instituto Carlos III (grants CP/00041 and PI19/00144) and by the Fundació La Marató de TV3 (201821‐30‐31‐32) to FL and by the Robert Koch Institute through funds from the Federal Ministry of Health (grant No, 1369‐341) to IZ. This project was also funded at 65% by the Fondo Europeo de Desarrollo Regional (FEDER) through the Interreg V‐A España‐Francia‐Andorra (POCTEFA 2014‐2020) programme. SJC is funded in part by a NHMRC Practitioner Fellowship (identification #APP1105784).S

Beryllium isotopes in central Arctic Ocean sediments over the past 12.3 million years: Stratigraphic and paleoclimatic implications

The upper 200 m of the sediments recovered during IODP Leg 302, the Arctic Coring Expedition (ACEX), to the Lomonosov Ridge in the central Arctic Ocean consist almost exclusively of detrital material. The scarcity of biostratigraphic markers severely complicates the establishment of a reliable chronostratigraphic framework for these sediments, which contain the first continuous record of the Neogene environmental and climatic evolution of the Arctic region. Here we present profiles of cosmogenic 10Be together with the seawater-derived fraction of stable 9Be obtained from the ACEX cores. The down-core decrease of 10Be/9Be provides an average sedimentation rate of 14.5 ± 1 m/Ma for the uppermost 151 m of the ACEX record and allows the establishment of a chronostratigraphy for the past 12.3 Ma. The age-corrected 10Be concentrations and 10Be/9Be ratios suggest the existence of an essentially continuous sea ice cover over the past 12.3 Ma

Hegel, Adorno and the origins of immanent criticism

‘Immanent criticism' has been discussed by philosophers of quite different persuasions, working in separate areas and in different traditions of philosophy. Almost all of them agree on roughly the same story about its origins: It is that Hegel invented immanent criticism, that Marx later developed it, and that the various members of the Frankfurt School, particularly Adorno, refined it in various ways, and that they are all paradigmatic practitioners of immanent criticism. I call this the Continuity Thesis. There are four different claims that interest me. (i) Hegel is the originator of immanent criticism. (ii) Hegel's dialectical method is that of immanent criticism. (iii) Adorno practises immanent criticism and endorses the term as a description of his practice. (iv) Adorno's dialectical method is fundamentally Hegelian. In this article, I offer an account of immanent criticism, on the basis of which, I evaluate these four claims and argue that the Continuity Thesis should be rejected

Connecting hydrological modelling and forecasting from global to local scales: perspectives from an international joint virtual workshop

The unprecedented progress in ensemble hydro-meteorological modelling and forecasting on a range of temporal and spatial scales, raises a variety of new challenges which formed the theme of the Joint Virtual Workshop, "Connecting global to local hydrological modelling and forecasting: challenges and scientific advances”. Held from 29 June to 1 July 2021, this workshop was co-organized by the European Centre for Medium-Range Weather Forecasts (ECMWF), the Copernicus Emergency Management (CEMS) and Climate Change (C3S) Services, the Hydrological Ensemble Prediction EXperiment (HEPEX), and the Global Flood Partnership (GFP). This paper aims to summarize the state-of-the-art presented at the workshop and provide an early career perspective. Recent advances in hydrological modelling and forecasting, reflections on the use of forecasts for decision-making across scales, and means to minimise new barriers to communication in the virtual format are also discussed. Thematic foci of the workshop included hydrological model development and skill assessment, uncertainty communication, forecasts for early action, co-production of services and incorporation of local knowledge, Earth Observation, and data assimilation. Connecting hydrological services to societal needs and local decision-making through effective communication, capacity-building and co-production was identified as critical. Multidisciplinary collaborations emerged as crucial to effectively bring newly developed tools to practice