41,719 research outputs found

    Nuclear emulsion recordings of heavy primaries on Apollo 7 and 8

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    Nuclear emulsion recordings of heavy primaries on Apollo 7 and

    Nuclear emulsion measurements of the astronauts' radiation exposures on Skylab missions 2, 3, and 4

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    On the Skylab missions, Ilford G.5 and K.2 emulsions were flown as part of passive dosimeter packs carried by the astronauts on their wrists. Due to the long mission times, latent image fading and track crowing imposed limitations on a quantitative track and grain count analysis. For Skylab 2, the complete proton energy spectrum was determined within reasonable error limits. A combined mission dose equivalent of 2,490 millirems from protons, tissue stars and neutrons was measured on Skylab 2. A stationary emulsion stack, kept in a film vault drawer on the same mission, displayed a highly structured directional distribution of the fluence of low-energy protons (enders) reflecting the local shield distribution. On the 59 and 84-day mission 3 and 4, G.5 emulsions had to be cut on the microtom to 5-7 microns for microscopic examination. Even so, the short track segments in such thin layers precluded a statistically reliable grain count analysis. However, the K.2 emulsions still allowed accurate proton ender counts without special provisions

    Nuclear emulsion measurements of the astronauts' radiation exposure on the Apollo-Soyuz mission

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    On the Apollo-Soyuz mission each astronaut carried one passive dosimeter containing nuclear photographic emulsions, plastic foils, TLD chips, and neutron-activation foils for recording radiation exposure. This report is limited to the presentation of data retrieved from nuclear emulsions. Protons, most of them trapped particles encountered in numerous passes through the South Atlantic Anomaly, contributed by far the largest share to the mission dose. Their linear energy transfer (LET) spectrum was established from track and grain counts in a G.5 emulsion which is used for medium and high energies, and from ender counts in a K.2 emulsion which is used for low energies. The total mission fluence of protons was found to be equivalent to a unidirectional beam of 448,500 square centimeters. The broad spectrum was broken down into small LET intervals, which allowed for the computation of absorbed doses and dose equivalents. The totals are 51 millirad and 74 millirem. Counts of disintegration stars in K.2 emulsion are incomplete at present. While a total of 467 stars were identified, counting their prong numbers is still in progress. It was concluded that the Apollo-Soyuz astronauts' radiation exposure as such did not contain anything out of the ordinary that would seem to require special attention

    Radiation monitoring with nuclear emulsions on Project Gemini. II. Results on the 14-day mission Gemini VII

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    Radiation monitoring results of small nuclear emulsion packs worn by astronauts on Gemini VI

    Nuclear emulsion measurements of the astronauts radiation exposure on Apollo 7

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    Nuclear emulsion measurements of astronaut radiation exposure on Apollo 7 fligh

    Strong convergence rates of probabilistic integrators for ordinary differential equations

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    Probabilistic integration of a continuous dynamical system is a way of systematically introducing model error, at scales no larger than errors introduced by standard numerical discretisation, in order to enable thorough exploration of possible responses of the system to inputs. It is thus a potentially useful approach in a number of applications such as forward uncertainty quantification, inverse problems, and data assimilation. We extend the convergence analysis of probabilistic integrators for deterministic ordinary differential equations, as proposed by Conrad et al.\ (\textit{Stat.\ Comput.}, 2017), to establish mean-square convergence in the uniform norm on discrete- or continuous-time solutions under relaxed regularity assumptions on the driving vector fields and their induced flows. Specifically, we show that randomised high-order integrators for globally Lipschitz flows and randomised Euler integrators for dissipative vector fields with polynomially-bounded local Lipschitz constants all have the same mean-square convergence rate as their deterministic counterparts, provided that the variance of the integration noise is not of higher order than the corresponding deterministic integrator. These and similar results are proven for probabilistic integrators where the random perturbations may be state-dependent, non-Gaussian, or non-centred random variables.Comment: 25 page

    Experiences of mindfulness training in living with rheumatic disease: an interpretative phenomenological analysis

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    This study examined experiences of Mindfulness training for 5 adults living with Rheumatic Disease. Focus group data was used to explore the experience and impact of Mindfulness training in participants aged between 46 and 69 diagnosed with Psoriatic Arthritis, Fibromyalgia or Rheumatoid Arthritis. All participants had completed an 8-week Mindfulness-Based Stress Reduction Programme (MBSR) 6 months prior to the study. Interpretative Phenomenological Analysis produced two themes: ‘responding to pain’ and ‘psychological well-being’. All participants spoke similarly and with enthusiasm, reflecting the strength of the impact of Mindfulness upon the daily lives of these individuals. Methodological limitations are considered along with clinical applications and suggestions for future research. The findings from this study reinforce the outcomes of previous research and indicate that Mindfulness has potential to improve the health and well-being of individuals living with Rheumatic Disease

    Bufo microscaphus

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    Number of Pages: 3Integrative BiologyGeological Science

    Proctolin and an Endogenous Proctolin-Like Peptide Enhance the Contractility of the Limulus Heart

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    Synthetic proctolin increases the force but not the rate of heart contractions of Limulus in a time- and dose-dependent manner. The threshold of this effect is 3 × 10−10M and the ED50 is approximately 10−8M. At concentrations up to 10−7 M, proctolin has no effect on the rhythmic electrical activity of the isolated cardiac ganglion, and it does not change the simple and compound postsynaptic potentials recorded at the cardiac neuromuscular junction. Proctolin acts directly on the cardiac muscle fibres. Electrically stimulated myocardia show a proctolin-induced increase in contraction amplitude with the same concentration dependence as the intact heart. A compound with an apparent molecular weight of 700–800 occurs in the Limulus nervous system, particularly in the cardiac ganglion. This compound resembles proctolin in being heat-stable, resistant to trypsin and chymotrypsin cleavage, and losing activity in a time-dependent manner in response to treatment with leucine aminopeptidase or pronase. This peptide induces spontaneous contractions and a contracture of the cockroach hindgut in a manner similar to proctolin. Moreover, the Limulus inotropic peptide, like proctolin, increases the force of contraction of the Limulus heart without affecting beat frequency. It is concluded that an endogenous, proctolin-like peptide is an inotropic modulator of the Limulus heart, acting directly on the muscle fibres and not affecting cardiac ganglion activity
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