1,299 research outputs found

    Evolutionary connectionism: algorithmic principles underlying the evolution of biological organisation in evo-devo, evo-eco and evolutionary transitions

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    The mechanisms of variation, selection and inheritance, on which evolution by natural selection depends, are not fixed over evolutionary time. Current evolutionary biology is increasingly focussed on understanding how the evolution of developmental organisations modifies the distribution of phenotypic variation, the evolution of ecological relationships modifies the selective environment, and the evolution of reproductive relationships modifies the heritability of the evolutionary unit. The major transitions in evolution, in particular, involve radical changes in developmental, ecological and reproductive organisations that instantiate variation, selection and inheritance at a higher level of biological organisation. However, current evolutionary theory is poorly equipped to describe how these organisations change over evolutionary time and especially how that results in adaptive complexes at successive scales of organisation (the key problem is that evolution is self-referential, i.e. the products of evolution change the parameters of the evolutionary process). Here we first reinterpret the central open questions in these domains from a perspective that emphasises the common underlying themes. We then synthesise the findings from a developing body of work that is building a new theoretical approach to these questions by converting well-understood theory and results from models of cognitive learning. Specifically, connectionist models of memory and learning demonstrate how simple incremental mechanisms, adjusting the relationships between individually-simple components, can produce organisations that exhibit complex system-level behaviours and improve the adaptive capabilities of the system. We use the term “evolutionary connectionism” to recognise that, by functionally equivalent processes, natural selection acting on the relationships within and between evolutionary entities can result in organisations that produce complex system-level behaviours in evolutionary systems and modify the adaptive capabilities of natural selection over time. We review the evidence supporting the functional equivalences between the domains of learning and of evolution, and discuss the potential for this to resolve conceptual problems in our understanding of the evolution of developmental, ecological and reproductive organisations and, in particular, the major evolutionary transitions

    An apparently normal gamma-ray burst with an unusually low luminosity

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    Much of progress in gamma-ray bursts has come from the studies of distant events (redshift z~1). The brightest GRBs are the most collimated events and seen across the Universe due to their brilliance. It has long been suspected that nearest (and most common) events have been missed because they are not so collimated or under-energetic or both. Here we report soft gamma-ray observations of GRB 031203, the nearest event to date (z=0.106). This event with a duration of 40 s and peak energy of >190 keV appears to be a typical long duration GRB. However, the isotropic gamma-ray energy <~10^50 erg, about three orders of magnitude smaller than the cosmological population. This event as well as the other nearby but somewhat controversial event GRB 980425 are clear outliers for the much discussed isotropic-energy peak-energy relation and luminosity spectral-lag relations. Radio calorimetry shows that both these events are under-energetic explosions. We conclude that there does indeed exist a large population of under-energetic events.Comment: 11 pages, 3 figure

    Hybrid managers, career narratives and identity work: a contextual analysis of UK healthcare organizations

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    While hybrid managers are increasingly important in contemporary organizations (especially in the public sector), we know little about why or how they become hybrid managers, or how this is shaped by the interplay of professional experience and organizational circumstances. In pursuit of a more variegated, contextualised and dynamic understanding of hybrid management, this paper focuses on how individuals transition into managerial hybrids, emphasizing the dynamic and emergent nature of hybrid management identity. Studying managers in English healthcare, we employ the concept of identity work as expressed through career narratives to examine the influence of career trajectories and organizational experiences on emerging hybrid manager identity. The study identifies three broad managerial career narratives – aspirational, ambivalent and agnostic – and relates them to experiences of doctor and nurse hybrid managers in three healthcare settings. An interpretive analysis of these narratives reveals a more variegated, situated and dynamic interpretation of hybrid managerial identities than previously considered and underscores the importance of personal and organizational experiences in shaping emergent hybrid professional/managerial identity

    Zircon ages in granulite facies rocks: decoupling from geochemistry above 850 °C?

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    Granulite facies rocks frequently show a large spread in their zircon ages, the interpretation of which raises questions: Has the isotopic system been disturbed? By what process(es) and conditions did the alteration occur? Can the dates be regarded as real ages, reflecting several growth episodes? Furthermore, under some circumstances of (ultra-)high-temperature metamorphism, decoupling of zircon U–Pb dates from their trace element geochemistry has been reported. Understanding these processes is crucial to help interpret such dates in the context of the P–T history. Our study presents evidence for decoupling in zircon from the highest grade metapelites (> 850 °C) taken along a continuous high-temperature metamorphic field gradient in the Ivrea Zone (NW Italy). These rocks represent a well-characterised segment of Permian lower continental crust with a protracted high-temperature history. Cathodoluminescence images reveal that zircons in the mid-amphibolite facies preserve mainly detrital cores with narrow overgrowths. In the upper amphibolite and granulite facies, preserved detrital cores decrease and metamorphic zircon increases in quantity. Across all samples we document a sequence of four rim generations based on textures. U–Pb dates, Th/U ratios and Ti-in-zircon concentrations show an essentially continuous evolution with increasing metamorphic grade, except in the samples from the granulite facies, which display significant scatter in age and chemistry. We associate the observed decoupling of zircon systematics in high-grade non-metamict zircon with disturbance processes related to differences in behaviour of non-formula elements (i.e. Pb, Th, U, Ti) at high-temperature conditions, notably differences in compatibility within the crystal structure

    Two-electron spin correlations in precision placed donors in silicon

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    Substitutional donor atoms in silicon are promising qubits for quantum computation with extremely long relaxation and dephasing times demonstrated. One of the critical challenges of scaling these systems is determining inter-donor distances to achieve controllable wavefunction overlap while at the same time performing high fidelity spin readout on each qubit. Here we achieve such a device by means of scanning tunnelling microscopy lithography. We measure anti-correlated spin states between two donor-based spin qubits in silicon separated by 16 ± 1 nm. By utilising an asymmetric system with two phosphorus donors at one qubit site and one on the other (2P−1P), we demonstrate that the exchange interaction can be turned on and off via electrical control of two in-plane phosphorus doped detuning gates. We determine the tunnel coupling between the 2P−1P system to be 200 MHz and provide a roadmap for the observation of two-electron coherent exchange oscillations

    The incredible complexity of RNA splicing

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    Alternative splice isoforms are common and important and have been shown to impact many human diseases. A new study by Nellore et al. offers a comprehensive study of splice junctions in humans by re-analyzing over 21,500 public human RNA sequencing datasets

    Evaluation of a commercial web-based weight loss and weight loss maintenance program in overweight and obese adults: a randomized controlled trial

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    <p>Abstract</p> <p>Background</p> <p>Obesity rates in adults continue to rise and effective treatment programs with a broad reach are urgently required. This paper describes the study protocol for a web-based randomized controlled trial (RCT) of a commercially available program for overweight and obese adult males and females. The aim of this RCT was to determine and compare the efficacy of two web-based interventions for weight loss and maintenance of lost weight.</p> <p>Methods/Design</p> <p>Overweight and obese adult males and females were stratified by gender and BMI and randomly assigned to one of three groups for 12-weeks: waitlist control, or basic or enhanced online weight-loss. Control participants were re-randomized to the two weight loss groups at the end of the 12-week period. The basic and enhanced group participants had an option to continue or repeat the 12-week program. If the weight loss goal was achieved at the end of 12, otherwise on completion of 24 weeks of weight loss, participants were re-randomized to one of two online maintenance programs (maintenance basic or maintenance enhanced), until 18 months from commencing the weight loss program. Assessments took place at baseline, three, six, and 18 months after commencing the initial weight loss intervention with control participants repeating the initial assessment after three month of waiting. The primary outcome is body mass index (BMI). Other outcomes include weight, waist circumference, blood pressure, plasma markers of cardiovascular disease risk, dietary intake, eating behaviours, physical activity and quality of life.</p> <p>Both the weight loss and maintenance of lost weight programs were based on social cognitive theory with participants advised to set goals, self-monitor weight, dietary intake and physical activity levels. The enhanced weight loss and maintenance programs provided additional personalized, system-generated feedback on progress and use of the program. Details of the methodological aspects of recruitment, inclusion criteria, randomization, intervention programs, assessments and statistical analyses are described.</p> <p>Discussion</p> <p>Importantly, this paper describes how an RCT of a currently available commercial online program in Australia addresses some of the short falls in the current literature pertaining to the efficacy of web-based weight loss programs.</p> <p>Australian New Zealand Clinical Trials Registry (ANZCTR) number: ACTRN12610000197033</p

    Co-designing inflammatory bowel disease (Ibd) services in Scotland : findings from a nationwide survey

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    Background: The Scottish Government’s ambition is to ensure that health services are co-designed with the communities they serve. Crohn’s and Colitis UK and the Scottish Government acknowledged the need to review and update the current IBD care model. An online survey was conducted asking IBD patients about their experiences of the NHS care they receive. This survey was the first step of co-designing and developing a national strategy for IBD service improvement in Scotland. Aim: To explore IBD patients’ experiences of current services and make recommendations for future service development. Methods: This study was part of a wider cross-sectional on-line survey. Participants were patients with IBD across Scotland. 777 people with IBD took part in the survey. Thematic analysis of all data was conducted independently by two researchers. Results: Three key themes emerged: Quality of life: Participants highlighted the impact the disease has on quality of life and the desperate need for IBD services to address this more holistically. IBD clinicians and access: Participants recognised the need for more IBD nurses and gastroenterologists along with better access to them. Those with a named IBD nurse reported to be more satisfied with their care. An explicit IBD care pathway: Patients with IBD identified the need of making the IBD care pathway more explicit to service users. Conclusions: Participants expressed the need for a more holistic approach to their IBD care. This includes integrating psychological, counselling and dietetic services into IBD care with better access to IBD clinicians and a more explicit IBD care pathway. Keywords: Inflammatory bowel disease, Co-designing, Qualitative study, Patient survey, Crohn’s disease, Ulcerative coliti

    Not lost in translation: Managerial career narratives and the construction of protean identities

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    How can managers remain in charge of their own careers based on personal values and motivations, rather than surrendering to the vulnerabilities of modern day corporate bureaucracies? This question represents a core issue for managers whose careers have been significantly affected by changing business environments, new organizational forms and the related changes of work organization in modern day corporations. Managers can no longer rely on the traditional linear models of organizational careers. It is increasingly demanded that they be more flexible and direct their own careers, which is captured in new career concepts, such as the ‘protean career’. Drawing on narrative identity theory, this study sets out to investigate how managers construct a protean identity and how specific narrative practices support individuals in shaping, implementing and defending this identity. The life stories of 29 individuals, all of whom have experienced significant career changes, are analysed. Based on these stories, four core narrative building blocks at the heart of protean identity construction and related narrative practices are identified, including (i) the discovery of conflicting expectations, (ii) the exploration of one’s own values and capabilities, (iii) the commitment to one’s own path and (iv) defending that path
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