5,773 research outputs found

    Novel methods for spatial prediction of soil functions within landscapes (SP0531)

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    Previous studies showed that soil patterns could be predicted in agriculturally managed landscapes by modelling and extrapolating from extensive existing but related integrated datasets. Based on these results we proposed to develop and apply predictive models of the relationships between environmental data and known soil patterns to predict capacity for key soil functions within diverse landscapes for which there is little detailed underpinning soil information available. Objectives were: To develop a high-level framework in which the non-specialist user-community could explore questions. To generate digital soil maps for three selected catchments at a target resolution of 1:50000 to provide the base information for soil function prediction. To use a modelling approach to predict the performance of key soil functions in catchments undergoing change but where only sparse or low resolution soil survey data are available. To use a modelling approach to assess the impact of different management scenarios and/or environmental conditions on the delivery of multiple soil functions within a catchment. To create a detailed outline of the requirements for ground-truthing to test the predicted model outputs at a catchment scale. To contribute to the development of a high-level framework for decision makers

    Upon the existence of short-time approximations of any polynomial order for the computation of density matrices by path integral methods

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    In this article, I provide significant mathematical evidence in support of the existence of short-time approximations of any polynomial order for the computation of density matrices of physical systems described by arbitrarily smooth and bounded from below potentials. While for Theorem 2, which is ``experimental'', I only provide a ``physicist's'' proof, I believe the present development is mathematically sound. As a verification, I explicitly construct two short-time approximations to the density matrix having convergence orders 3 and 4, respectively. Furthermore, in the Appendix, I derive the convergence constant for the trapezoidal Trotter path integral technique. The convergence orders and constants are then verified by numerical simulations. While the two short-time approximations constructed are of sure interest to physicists and chemists involved in Monte Carlo path integral simulations, the present article is also aimed at the mathematical community, who might find the results interesting and worth exploring. I conclude the paper by discussing the implications of the present findings with respect to the solvability of the dynamical sign problem appearing in real-time Feynman path integral simulations.Comment: 19 pages, 4 figures; the discrete short-time approximations are now treated as independent from their continuous version; new examples of discrete short-time approximations of order three and four are given; a new appendix containing a short review on Brownian motion has been added; also, some additional explanations are provided here and there; this is the last version; to appear in Phys. Rev.

    Revisiting Neurofibromatosis type 2 diagnostic criteria to exclude LZTR1 related schwannomatosis

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    OBJECTIVE: To determine the specificity of the current clinical diagnostic criteria for neurofibromatosis type 2 (NF2) relative to the requirement for unilateral vestibular schwannoma (VS) and at least 2 other NF2-related tumors. METHODS: We interrogated our Manchester NF2 database, which contained 205 individuals meeting NF2 criteria who initially presented with a unilateral VS. Of these, 83 (40.7%) went on to develop a contralateral VS. We concentrated our genetic analysis on a group of 70 who initially fulfilled NF2 criteria with a unilateral vestibular schwannoma and at least 2 additional nonintradermal schwannomas. RESULTS: Overall, 5/70 (7%) individuals with unilateral VS and at least 2 other schwannomas had a pathogenic or likely pathogenic LZTR1 mutation. Twenty of the 70 subsequently developed bilateral disease. Of the remaining 50, 5 (10%) had a germline LZTR1 mutation, equivalent to the number (n = 5) with a germline NF2 mutation. CONCLUSIONS: The most common etiology for unilateral VS and 2 additional NF2-associated tumors in this cohort was mosaic NF2. Germline LZTR1 and germline NF2 mutations were equally common in our cohort. This indicates that LZTR1 must be considered when making a diagnosis of NF2 in the presence of unilateral VS in individuals without a germline NF2 mutation

    Fatty acid nitroalkenes ameliorate glucose intolerance and pulmonary hypertension in high-fat diet-induced obesity

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    Aims Obesity is a risk factor for diabetes and cardiovascular diseases, with the incidence of these disorders becoming epidemic. Pathogenic responses to obesity have been ascribed to adipose tissue (AT) dysfunction that promotes bioactive mediator secretion from visceral AT and the initiation of pro-inflammatory events that induce oxidative stress and tissue dysfunction. Current understanding supports that suppressing pro-inflammatory and oxidative events promotes improved metabolic and cardiovascular function. In this regard, electrophilic nitro-fatty acids display pleiotropic anti-inflammatory signalling actions. Methods and results It was hypothesized that high-fat diet (HFD)-induced inflammatory and metabolic responses, manifested by loss of glucose tolerance and vascular dysfunction, would be attenuated by systemic administration of nitrooctadecenoic acid (OA-NO2). Male C57BL/6j mice subjected to a HFD for 20 weeks displayed increased adiposity, fasting glucose, and insulin levels, which led to glucose intolerance and pulmonary hypertension, characterized by increased right ventricular (RV) end-systolic pressure (RVESP) and pulmonary vascular resistance (PVR). This was associated with increased lung xanthine oxidoreductase (XO) activity, macrophage infiltration, and enhanced expression of pro-inflammatory cytokines. Left ventricular (LV) end-diastolic pressure remained unaltered, indicating that the HFD produces pulmonary vascular remodelling, rather than LV dysfunction and pulmonary venous hypertension. Administration of OA-NO2 for the final 6.5 weeks of HFD improved glucose tolerance and significantly attenuated HFD-induced RVESP, PVR, RV hypertrophy, lung XO activity, oxidative stress, and pro-inflammatory pulmonary cytokine levels. Conclusions These observations support that the pleiotropic signalling actions of electrophilic fatty acids represent a therapeutic strategy for limiting the complex pathogenic responses instigated by obesity.Fil: Kelley, Eric E.. University of Pittsburgh; Estados UnidosFil: Baust, Jeff. University of Pittsburgh; Estados UnidosFil: Bonacci, Gustavo Roberto. University of Pittsburgh; Estados Unidos. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico CĂłrdoba. Centro de Investigaciones en BioquĂ­mica ClĂ­nica e InmunologĂ­a; ArgentinaFil: Golin Bisello, Franca. University of Pittsburgh; Estados UnidosFil: Devlin, Jason E.. University of Pittsburgh; Estados UnidosFil: Croix, Claudette M. St.. University of Pittsburgh; Estados UnidosFil: Watkins, Simon C.. University of Pittsburgh; Estados UnidosFil: Gor, Sonia. University of Pittsburgh; Estados UnidosFil: Cantu Medellin, Nadiezhda. University of Pittsburgh; Estados UnidosFil: Weidert, Eric R.. University of Pittsburgh; Estados UnidosFil: Frisbee,Jefferson C.. University of Virginia; Estados UnidosFil: Gladwin, Mark T.. University of Pittsburgh; Estados UnidosFil: Champion, Hunter C.. University of Pittsburgh; Estados UnidosFil: Freeman, Bruce A.. University of Pittsburgh; Estados UnidosFil: Khoo, Nicholas K.H.. University of Pittsburgh; Estados Unido

    Willingness of children and adolescents to have a COVID-19 vaccination: Results of a large whole schools survey in England.

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    BackgroundVaccine hesitancy has affected COVID-19 adult vaccination programs in many countries. Data on hesitancy amongst child and adolescent populations is largely confined to parent opinion. We investigated the characteristics of vaccine hesitant children and adolescents using results from a large, school-based self-report survey of the willingness to have a COVID-19 vaccination in students aged 9 -18 years in England.MethodsData from the OxWell Student Survey on mental health, life experiences and behaviours were used, collected from four counties across England. Local authority partners recruited schools. The vaccine hesitancy question gave six response options and were clustered to inform delivery: eager and willing were categorised as vaccination 'opt-in', don't know and not bothered categorised as 'undecided', and unwilling and anti-vaccination categorised as 'opt-out'. We conducted a multinomial regression to determine associations between vaccine hesitancy and sociodemographic, health behaviour and social connection variables.Findings27,910 students from 180 schools answered the vaccine hesitancy question between 14th May and 21st July 2021, of whom 13984 (50.1%) would opt-in to take a vaccination, 10322 (37.0%) were undecided, and 3604 (12.9%) would opt-out. A lower percentage of younger students reported that they would opt-in to vaccination, for example, 35.7% of 9-year-olds and 51.3% of 13-year-olds compared to 77.8% of 17-year-olds would opt-in to take a vaccination. Students who were 'opt-out' or 'undecided' (a combined 'vaccine hesitant' group) were more likely to come from deprived socioeconomic contexts with higher rates of home rental versus home ownership and their school locations were more likely to be in areas of greater deprivation. They were more likely to smoke or vape, spend longer on social media, feel that they did not belong in their school community but had lower levels of anxiety and depression. The vaccine hesitant students- the undecided and opt-out groups- were similar in profile, although the opt-out students had higher reported confirmed or probable previous COVID-19 infection than the opt-in group, whereas those undecided, did not.InterpretationIf government vaccination strategies move towards vaccinating younger school-aged students, efforts to increase vaccination uptake may be necessary. Compared with students who would opt-in, those who were vaccine hesitant had greater indicators of social deprivation and felt a lack of community cohesion by not feeling a sense of belonging at their school. There were indications that those students who would opt-out had higher levels of marginalisation and mistrust. If programmes are rolled out, focus on hesitant younger students will be important, targeting more marginalised and deprived young people with information from trusted sources utilising social media; improving access to vaccination centres with provision both in and outside school; and addressing fears and worries about the effects of the vaccine. The main limitation of this study is that the participant group may not be wholly representative of England or the UK, which may bias population-level estimates of willingness to be vaccinated.FundingThe Westminster Foundation, the National Institute for Health Research (NIHR) Applied Research Collaboration Oxford and Thames Valley at Oxford Health NHS Foundation Trust and the NIHR Oxford Health Biomedical Research Centre

    The ANU WiFeS SuperNovA Program (AWSNAP)

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    This paper presents the first major data release and survey description for the ANU WiFeS SuperNovA Program (AWSNAP). AWSNAP is an ongoing supernova spectroscopy campaign utilising the Wide Field Spectrograph (WiFeS) on the Australian National University (ANU) 2.3m telescope. The first and primary data release of this program (AWSNAP-DR1) releases 357 spectra of 175 unique objects collected over 82 equivalent full nights of observing from July 2012 to August 2015. These spectra have been made publicly available via the WISeREP supernova spectroscopy repository. We analyse the AWSNAP sample of Type Ia supernova spectra, including measurements of narrow sodium absorption features afforded by the high spectral resolution of the WiFeS instrument. In some cases we were able to use the integral-field nature of the WiFeS instrument to measure the rotation velocity of the SN host galaxy near the SN location in order to obtain precision sodium absorption velocities. We also present an extensive time series of SN 2012dn, including a near-nebular spectrum which both confirms its "super-Chandrasekhar" status and enables measurement of the sub-solar host metallicity at the SN site.Comment: Submitted to Publications of the Astronomical Society of Australia (PASA). Spectra publicly released via WISeREP at http://wiserep.weizmann.ac.il

    Application of <sup>14</sup>C analyses to source apportionment of carbonaceous PM<sub>2.5</sub> in the UK

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    Determination of the radiocarbon (&lt;sup&gt;14&lt;/sup&gt;C) content of airborne particulate matter yields insight into the proportion of the carbonaceous material derived from fossil and contemporary carbon sources. Daily samples of PM&lt;sub&gt;2.5&lt;/sub&gt; were collected by high-volume sampler at an urban background site in Birmingham, UK, and the fraction of &lt;sup&gt;14&lt;/sup&gt;C in both the total carbon, and in the organic and elemental carbon fractions, determined by two-stage combustion to CO&lt;sub&gt;2&lt;/sub&gt;, graphitisation and quantification by accelerator mass spectrometry. OC and EC content was also determined by Sunset Analyzer. The mean fraction contemporary TC in the PM&lt;sub&gt;2.5&lt;/sub&gt; samples was 0.50 (range 0.27–0.66, n = 26). There was no seasonality to the data, but there was a positive trend between fraction contemporary TC and magnitude of SOC/TC ratio and for the high values of these two parameters to be associated with air-mass back trajectories arriving in Birmingham from over land. Using a five-compartment mass balance model on fraction contemporary carbon in OC and EC, the following average source apportionment for the TC in these PM&lt;sub&gt;2.5&lt;/sub&gt; samples was derived: 27% fossil EC; 20% fossil OC; 2% biomass EC; 10% biomass OC; and 41% biogenic OC. The latter category will comprise, in addition to BVOC-derived SOC, other non-combustion contemporary carbon sources such as biological particles, vegetative detritus, humic material and tyre wear. The proportion of total PM&lt;sub&gt;2.5&lt;/sub&gt; at this location estimated to derive from BVOC-derived secondary organic aerosol was 9–29%. The findings from this work are consistent with those from elsewhere in Europe and support the conclusion of a significant and ubiquitous contribution from non-fossil biogenic sources to the carbon in terrestrial aerosol

    A Catalog of Chandra X-ray Sources in the Carina Nebula

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    We present a catalog of ~14,000 X-ray sources observed by the ACIS instrument on the Chandra X-ray Observatory within a 1.42 square degree survey of the Great Nebula in Carina, known as the Chandra Carina Complex Project (CCCP). This study appears in a Special Issue of the ApJS devoted to the CCCP. Here, we describe the data reduction and analysis procedures performed on the X-ray observations, including calibration and cleaning of the X-ray event data, point source detection, and source extraction. The catalog appears to be complete across most of the field to an absorption-corrected total-band luminosity of ~10^{30.7} erg/s for a typical low-mass pre-main sequence star. Counterparts to the X-ray sources are identified in a variety of visual, near-infrared, and mid-infrared surveys. The X-ray and infrared source properties presented here form the basis of many CCCP studies of the young stellar populations in Carina.Comment: Accepted for the ApJS Special Issue on the Chandra Carina Complex Project (CCCP), scheduled for publication in May 2011. All 16 CCCP Special Issue papers are available at http://cochise.astro.psu.edu/Carina_public/special_issue.html through 2011 at least. 29 pages, 11 figure

    Bang-bang control of fullerene qubits using ultra-fast phase gates

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    Quantum mechanics permits an entity, such as an atom, to exist in a superposition of multiple states simultaneously. Quantum information processing (QIP) harnesses this profound phenomenon to manipulate information in radically new ways. A fundamental challenge in all QIP technologies is the corruption of superposition in a quantum bit (qubit) through interaction with its environment. Quantum bang-bang control provides a solution by repeatedly applying `kicks' to a qubit, thus disrupting an environmental interaction. However, the speed and precision required for the kick operations has presented an obstacle to experimental realization. Here we demonstrate a phase gate of unprecedented speed on a nuclear spin qubit in a fullerene molecule (N@C60), and use it to bang-bang decouple the qubit from a strong environmental interaction. We can thus trap the qubit in closed cycles on the Bloch sphere, or lock it in a given state for an arbitrary period. Our procedure uses operations on a second qubit, an electron spin, in order to generate an arbitrary phase on the nuclear qubit. We anticipate the approach will be vital for QIP technologies, especially at the molecular scale where other strategies, such as electrode switching, are unfeasible
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