1,531 research outputs found

    Investigation of the Mechanisms of 6-Li-Induced Reactions Far Above the Coulomb Barrier

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    This work was supported by National Science Foundation Grants PHY 76-84033A01, PHY 78-22774, and Indiana Universit

    Systematics of Charged-Particle Products from Reactions Induced by 95-MeV 6-Li

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    This work was supported by National Science Foundation Grant PHY 76-84033 and Indiana Universit

    Resolving the ā€˜Nitrogen Paradoxā€™ of arbuscular mycorrhizas : fertilization with organic matter brings considerable benefits for plant nutrition and growth

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    Arbuscular mycorrhizal fungi (AMF) can transfer nitrogen (N) to host plants but the ecological relevance is debated, as total plant N and biomass do not generally increase. The extent to which the symbiosis is mutually beneficial is thought to rely on the stoichiometry of N, phosphorus (P) and carbon (C) availability. While inorganic N fertilisation has been shown to elicit strong mutualism, characterised by improved plant and fungal growth and mineral nutrition, similar responses following organic N addition are lacking. Using a compartmented microcosm experiment, we determined the significance to a mycorrhizal plant of placing a 15Nā€labelled, nitrogenā€rich patch of organic matter in a compartment to which only AMF hyphae had access. Control microcosms denied AMF hyphal access to the patch compartment. When permitted access to the patch compartment, the fungus proliferated extensively in the patch and transferred substantial quantities of N to the plant. Moreover, our data demonstrate that allowing hyphal access to an organic matter patch enhanced total plant N and P contents, with a simultaneous and substantial increase in plant biomass. Moreover, we demonstrate that organic matter fertilization of arbuscular mycorrhizal plants can foster a mutually beneficial symbiosis based on nitrogen transfer, a phenomenon previously thought irrelevant

    Living HTA: automating health economic evaluation with R

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    Background: Requiring access to sensitive data can be a significant obstacle for the development of health models in the Health Economics & Outcomes Research (HEOR) setting. We demonstrate how health economic evaluation can be conducted with minimal transfer of data between parties, while automating reporting as new information becomes available. Methods: We developed an automated analysis and reporting pipeline for health economic modelling and made the source code openly available on a GitHub repository. The pipeline consists of three parts: An economic model is constructed by the consultant using pseudo data. On the data-owner side, an application programming interface (API) is hosted on a server. This API hosts all sensitive data, so that data does not have to be provided to the consultant. An automated workflow is created, which calls the API, retrieves results, and generates a report. Results: The application of modern data science tools and practices allows analyses of data without the need for direct access ā€“ negating the need to send sensitive data. In addition, the entire workflow can be largely automated: the analysis can be scheduled to run at defined time points (e.g. monthly), or when triggered by an event (e.g. an update to the underlying data or model code); results can be generated automatically and then be exported into a report. Documents no longer need to be revised manually. Conclusions: This example demonstrates that it is possible, within a HEOR setting, to separate the health economic model from the data, and automate the main steps of the analysis pipeline

    Gibbons-Hawking M-branes

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    We present new M2 and M5-brane solutions in M-theory based on transverse Gibbons-Hawking spaces. These solutions provide realizations of fully localized type IIA D2/D6 and NS5/D6 brane intersections. One novel feature of these solutions is that the metric functions depend on more than two transverse coordinates (unlike all the other previous known solutions). All the solutions have eight preserved supersymmetries and the world-volume theories of the NS5-branes are new non-local, non-gravitational, six dimensional, T-dual little string theories with eight supersymmetries. We discuss the limits in which the dynamics of the D2 and NS5-branes decouple from the bulk for these solutions.Comment: 32 pages, 7 figures, few sentences added, a couple of typos corrected, to appear in JHE

    Where should new parkrun events be located? Modelling the potential impact of 200 new events on socio-economic inequalities in access and participation

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    Background parkrun, an international movement which organises free weekly 5km running events, has been widely praised for encouraging inactive individuals to participate in physical activity. Recently, parkrun received funding to establish 200 new events across England, specifically targeted at deprived communities. This study aims to investigate the relationships between geographic access, deprivation, and participation in parkrun, and to inform the planned expansion by proposing future event locations. Methods We conducted an ecological spatial analysis, using data on 455 parkrun events, 2,842 public green spaces, and 32,844 English census areas. Poisson regression was applied to investigate the relationships between the distances to events, deprivation, and parkrun participation rates. Model estimates were incorporated into a location-allocation analysis, to identify locations for future events that maximise deprivation-weighted parkrun participation. Results The distance to the nearest event (in km) and the Index of Multiple Deprivation (score) were both independently negatively associated with local parkrun participation rates. Rate ratios were 0.921 (95%CI = 0.921-0.922) and 0.959 (0.959-0.959), respectively. The recommended 200 new event locations were estimated to increase weekly runs by 6.9% (from 82,824 to 88,506). Of the additional runs, 4.1% (n=231) were expected to come from the 10% most deprived communities. Conclusion Participation in parkrun is wide spread across England. We provide recommendations for new parkrun event location, in order to increase participation from deprived communities. However, the creation of new events alone is unlikely to be an effective strategy. Further research is needed to study how barriers to participation can be reduced

    Constraining the variation of the coupling constants with big bang nucleosynthesis

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    We consider the possibility of the coupling constants of the SU(3)ƗSU(2)ƗU(1)SU(3)\times SU(2)\times U(1) gauge interactions at the time of big bang nucleosynthesis having taken different values from what we measure at present, and investigate the allowed difference requiring the shift in the coupling constants not violate the successful calculation of the primordial abundances of the light elements. We vary gauge couplings and Yukawa couplings (fermion masses) using a model in which their relative variations are governed by a single scalar field, dilaton, as found in string theory. The results include a limit on the fine structure constant āˆ’6.0Ɨ10āˆ’4<Ī”Ī±EM/Ī±EM<1.5Ɨ10āˆ’4-6.0\times10^{-4}<\Delta\alpha_{EM}/\alpha_{EM}<1.5\times10^{-4}, which is two orders stricter than the limit obtained by considering the variation of Ī±EM\alpha_{EM} alone.Comment: 7 page

    Herschel spectroscopic observations of the compact obscured nucleus in Zw 049.057

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    Context. The luminous infrared galaxy Zw 049.057 contains a compact obscured nucleus where a considerable amount of the galaxy's luminosity is generated. This nucleus contains a dusty environment that is rich in molecular gas. One approach to probing this kind of environment and to revealing what is hidden behind the dust is to study the rotational lines of molecules that couple well with the infrared radiation emitted by the dust. Aims. We probe the physical conditions in the core of Zw 049.057 and establish the nature of its nuclear power source (starburst or active galactic nucleus). Methods. We observed Zw 049.057 with the Photodetector Array Camera and Spectrometer (PACS) and the Spectral and Photometric Imaging Receiver (SPIRE) onboard the Herschel Space Observatory in rotational lines of H<inf>2</inf>O, H<inf>2</inf><sup>18</sup>O, OH, <sup>18</sup>OH, and [O I]. We modeled the unresolved core of the galaxy using a spherically symmetric radiative transfer code. To account for the different excitation requirements of the various molecular transitions, we use multiple components and different physical conditions. Results. We present the full high-resolution SPIRE FTS spectrum of Zw 049.057, along with relevant spectral scans in the PACS range. We find that a minimum of two different components (nuclear and extended) are required in order to account for the rich molecular line spectrum of Zw 049.057. The nuclear component has a radius of 10-30 pc, a very high infrared surface brightness (āˆ¼10<sup>14</sup>L<inf>āŠ™</inf>kpc<sup>-2</sup>), warm dust (T<inf>d</inf> > 100 K), and a very large H<inf>2</inf> column density (N<inf>H</inf><inf>2</inf> = 10<sup>24</sup>-10<sup>25</sup> cm<sup>-2</sup>). The modeling also indicates high nuclear H<inf>2</inf>O (āˆ¼5 Ɨ 10<sup>-6</sup>) and OH (āˆ¼4 Ɨ 10<sup>-6</sup>) abundances relative to H<inf>2</inf> as well as a low <sup>16</sup>O/<sup>18</sup>O-ratio of 50-100. We also find a prominent infall signature in the [O I] line. We tentatively detect a 500 km s<sup>-1</sup> outflow in the H<inf>2</inf>O 3<inf>13</inf> ā†’ 2<inf>02</inf> line. Conclusions. The high surface brightness of the core indicates the presence of either a buried active galactic nucleus or a very dense nuclear starburst. The estimated column density towards the core of Zw 049.057 indicates that it is Compton-thick, making a buried X-ray source difficult to detect even in hard X-rays. We discuss the elevated H<inf>2</inf>O abundance in the nucleus in the context of warm grain and gas-phase chemistry. The H<inf>2</inf>O abundance is comparable to that of other compact (ultra-)luminous infrared galaxies such as NGC 4418 and Arp 220 - and also to hot cores in the Milky Way. The enhancement of <sup>18</sup>O is a possible indicator that the nucleus of Zw 049.057 is in a similar evolutionary stage as the nuclei of Arp 220 - and more advanced than NGC 4418. We discuss the origin of the extreme nuclear gas concentration and note that the infalling gas detected in [O I] implies that the gas reservoir in the central region of Zw 049.057 is being replenished. If confirmed, the H<inf>2</inf>O outflow suggests that the nucleus is in a stage of rapid evolution

    ISML: an interface specification meta-language

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    In this paper we present an abstract metaphor model situated within a model-based user interface framework. The inclusion of metaphors in graphical user interfaces is a well established, but mostly craft-based strategy to design. A substantial body of notations and tools can be found within the model-based user interface design literature, however an explicit treatment of metaphor and its mappings to other design views has yet to be addressed. We introduce the Interface Specification Meta-Language (ISML) framework and demonstrate its use in comparing the semantic and syntactic features of an interactive system. Challenges facing this research are outlined and further work proposed
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