3,931 research outputs found

    Emergence of long-range order in BaTiO3 from local symmetry-breaking distortions

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    By using a symmetry motivated basis to evaluate local distortions against pair distribution function data (PDF), we show without prior bias, that the off-centre Ti displacements in the archetypal ferroelectric BaTiO3 are zone centred and rhombohedral-like in nature across its known ferroelectric and paraelectric phases. With our newly-gained insight we construct a simple Monte Carlo (MC) model which captures our main experimental findings and demonstrate how the rich crystallographic phase diagram of BaTiO3 emerges from correlations of local symmetry-breaking distortions alone. Our results strongly support the order-disorder picture for these phase transitions, but can also be reconciled with the soft-mode theory of BaTiO3 that is supported by some spectroscopic techniques.Comment: 5 pages, 3 figure

    Fast, Automated Implementation of Temporally Precise Blind Deconvolution of Multiphasic Excitatory Postsynaptic Currents

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    Records of excitatory postsynaptic currents (EPSCs) are often complex, with overlapping signals that display a large range of amplitudes. Statistical analysis of the kinetics and amplitudes of such complex EPSCs is nonetheless essential to the understanding of transmitter release. We therefore developed a maximum-likelihood blind deconvolution algorithm to detect exocytotic events in complex EPSC records. The algorithm is capable of characterizing the kinetics of the prototypical EPSC as well as delineating individual release events at higher temporal resolution than other extant methods. The approach also accommodates data with low signal-to-noise ratios and those with substantial overlaps between events. We demonstrated the algorithm’s efficacy on paired whole-cell electrode recordings and synthetic data of high complexity. Using the algorithm to align EPSCs, we characterized their kinetics in a parameter-free way. Combining this approach with maximum-entropy deconvolution, we were able to identify independent release events in complex records at a temporal resolution of less than 250 µs. We determined that the increase in total postsynaptic current associated with depolarization of the presynaptic cell stems primarily from an increase in the rate of EPSCs rather than an increase in their amplitude. Finally, we found that fluctuations owing to postsynaptic receptor kinetics and experimental noise, as well as the model dependence of the deconvolution process, explain our inability to observe quantized peaks in histograms of EPSC amplitudes from physiological recordings

    Primase-polymerases are a functionally diverse superfamily of replication and repair enzymes

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    Until relatively recently, DNA primases were viewed simply as a class of proteins that synthesize short RNA primers requisite for the initiation of DNA replication. However, recent studies have shown that this perception of the limited activities associated with these diverse enzymes can no longer be justified. Numerous examples can now be cited demonstrating how the term 'DNA primase' only describes a very narrow subset of these nucleotidyltransferases, with the vast majority fulfilling multifunctional roles from DNA replication to damage tolerance and repair. This article focuses on the archaeo-eukaryotic primase (AEP) superfamily, drawing on recently characterized examples from all domains of life to highlight the functionally diverse pathways in which these enzymes are employed. The broad origins, functionalities and enzymatic capabilities of AEPs emphasizes their previous functional misannotation and supports the necessity for a reclassification of these enzymes under a category called primase-polymerases within the wider functional grouping of polymerases. Importantly, the repositioning of AEPs in this way better recognizes their broader roles in DNA metabolism and encourages the discovery of additional functions for these enzymes, aside from those highlighted here

    Glucose Inhibition of Cellulose Synthesis by Pyrenochaeta terrestris

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    The rate of synthesis of Pyrenochacta terrestris cellulase was determined on the substrates of glucose, cellulose, and cellulose + glucose. Enzyme production was rapid on cellulose, almost negligible on glucose, and intermediate on cellulose + glucose. On the latter substrate, cellulase appeared after the near exhaustion of glucose. The authors suggest that extremely low concentrations of soluble carbohydrate regulate cellulase synthesis

    Participatory research approaches to integrating scientific and farmer knowledge of soil to meet multiple objectives in the English East Midlands

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    Soil management influences food production, economic performance of farm businesses, and a range of public benefits such as water quality, flood control and aquatic and terrestrial biodiversity. The aim of this paper is to explore the role of participatory research in combining scientific and farmer knowledge of soils to meet these multiple objectives. We use five separate research studies involving communication, consultation and co‐production, carried out in the English East Midlands between 2014 and 2018.We compare the participatory processes for knowledge exchange and their material outcomes and assess them retrospectively against specified criteria for successful application of participatory research. We conclude that, depending on context and scalar fit, multiple approaches to participatory research can be complementary, strengthen engagement and build trust within a farming community, resulting in a greater shared understanding of how to address the soil management objectives of farmers and wider society

    The Italian Angevins: Naples and Beyond, 1266–1343

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    Is it feasible to conduct a randomised controlled trial of pretransplant exercise (prehabilitation) for patients with multiple myeloma awaiting autologous haematopoietic stem cell transplantation? Protocol for the PREeMPT study

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    Introduction While myeloma is an incurable malignancy, developments in disease management have led to increased life expectancy in recent years. Treatment typically involves stem-cell transplantation. Increased survival rates equate to more patients living with the burden of both the disease and its treatment for increasing number of years, rendering myeloma a long-term condition. Evidence exists to demonstrate the benefits of exercise for patients recovering from stem-cell transplantation, and prehabilitation—exercise before treatment—has been shown to be effective in other disease areas. To date there has been no research into prehabilitation in patients with myeloma awaiting transplantation treatment. Our objective is to determine whether it is feasible to conduct a randomised controlled trial into pretransplant exercise for patients with multiple myeloma who are awaiting autologous stem-cell transplantation. Methods and analysis This mixed methods study identifies patients with diagnosis of multiple myeloma who have been assigned to the autologous transplantation list and invites them to participate in six weekly sessions of individualised, supervised exercise while awaiting transplantation. Quantitative data to determine feasibility targets include rates of recruitment, adherence and adverse events, and outcome measures including 6 min walking distance test and quality of life. Qualitative interviews are undertaken with a purposive sample of patients to capture their experiences of the study and the intervention
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