5,928 research outputs found

    Direct stimulation of the retina by the method of virtual-quanta for heavy cosmic-ray nuclei

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    The contribution to the frequency of visual sensations induced in the dark-adapted eye by the virtual photon field was calculated, this field is associated with the heavy nuclei that exist in space beyond the geomagnetic field. In order to determine the probability that the virtual photon field induces a light flash, only the portion of the virtual photon spectrum that corresponds to the known frequency dependence of the sensitivity of human rods to visible light was utilized. The results can be expressed as a curve of the mean frequency of light flashes induced by the absorption of at least R virtual photons versus the threshold number R. The contribution to the light flash frequency from the virtual photon field of heavy cosmic ray nuclei is smaller than that from Cerenkov photons. The flux and energy spectra of galactic cosmic ray nuclei helium to iron were used

    Light flash phenomena induced by HzE particles

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    Astronauts and Apollo and Skylab missions have reported observing a variety of visual phenomena when their eyes are closed and adapted to darkness. These phenomena have been collectively labelled as light flashes. Visual phenomena which are similar in appearance to those observed in space have been demonstrated at the number of accelerator facilities by expressing the eyes of human subjects to beams of various types of radiation. In some laboratory experiments Cerenkov radiation was found to be the basis for the flashes observed while in other experiments Cerenkov radiation could apparently be ruled out. Experiments that differentiate between Cerenkov radiation and other possible mechanisms for inducing visual phenomena was then compared. The phenomena obtained in the presence and absence of Cerenkov radiation were designed and conducted. A new mechanism proposed to explain the visual phenomena observed by Skylab astronauts as they passed through the South Atlantic Anomaly, namely nuclear interactions in and near the sensitive layer of the retina, is covered. Also some studies to search for similar transient effects of space radiation on sensors and microcomputer memories are described

    On the Impossibility to Extend Triples of Mutually Unbiased Product Bases in Dimension Six

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    An analytic proof is given which shows that it is impossible to extend any triple of mutually unbiased (MU) product bases in dimension six by a single MU vector. Furthermore, the 16 states obtained by removing two orthogonal states from any MU product triple cannot figure in a (hypothetical) complete set of seven MU bases. These results follow from exploiting the structure of MU product bases in a novel fashion, and they are among the strongest ones obtained for MU bases in dimension six without recourse to computer algebra.Comment: 12 pages, identical to published versio

    Evaluation of techniques for removal of spacecraft contaminants from activated carbon

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    Alternative techniques for the regeneration of carbon contaminated with various spacecraft contaminants were evaluated. Four different modes of regeneration were evaluated: (1) thermal desorption via vacuum, (2) thermal desorption via nitrogen purge, (3) in-situ catalytic oxidation of adsorbed contaminants, and (4) in-situ non-catalytic oxidation of adsorbed contaminants

    Regeneration in gap models: priority issues for studying forest responses to climate change

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    Recruitment algorithms in forest gap models are examined with particular regard to their suitability for simulating forest ecosystem responses to a changing climate. The traditional formulation of recruitment is found limiting in three areas. First, the aggregation of different regeneration stages (seed production, dispersal, storage, germination and seedling establishment) is likely to result in less accurate predictions of responses as compared to treating each stage separately. Second, the relatedassumptions that seeds of all species are uniformly available and that environmental conditions are homogeneous, are likely to cause overestimates of future species diversity and forest migration rates. Third, interactions between herbivores (ungulates and insect pests) and forest vegetation are a big unknown with potentially serious impacts in many regions. Possible strategies for developing better gap model representations for the climate-sensitive aspects of each of these key areas are discussed. A working example of a relatively new model that addresses some of these limitations is also presented for each case. We conclude that better models of regeneration processes are desirable for predicting effects of climate change, but that it is presently impossible to determine what improvements can be expected without carrying out rigorous tests for each new formulation

    Patient safety in undergraduate radiography curricula : a European perspective

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    Purpose: To establish an understanding of patient safety within radiography education across Europe by surveying higher education institutions registered as affiliate members of the European Federation of Radiographer Societies (EFRS). Method: An online survey was developed to ascertain data on: programme type, patient safety definitions, relevant safety topics, specific areas taught, teaching and assessment methods, levels of teaching and curriculum drivers. Responses were identifiable in terms of educational institution and country. All 54 affiliated educational institutions were invited to participate. Descriptive and thematic analyses are reported. Results: A response rate of 61.1% (n = 33) was achieved from educational institutions representing 19 countries. Patient safety topics appear to be extremely well covered across curricula, however, topics including radiation protection and optimisation were not reported as being taught at an ‘advanced level’ by five and twelve respondents, respectively. Respondents identified the clinical department as the location of most patient safety-related teaching. Conclusions: Patient safety topics are deeply embedded within radiography curricula across Europe. Variations exist in terms of individual safety topics included, teaching and assessment methods, and the depth in which subjects are taught. Results from this study provide a baseline for assessing developments in curricula and can also serve as a benchmark for comparisons

    Evaluation of the quality and impact of online learning through the SAFE EUROPE webinars

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    IntroductionThe SAFE EUROPE project, a European-funded project, addressed educational gaps of Therapeutic Radiographers/Radiation Therapists (TR/RTTs) by offering a series of free webinars. This study aimed to assess the quality of these webinars and their impact on professional practice.MethodsData collection involved two methods: an automated feedback form administered after each webinar, supplemented by a survey disseminated through social media. The collected data encompassed attendance statistics, participants’ professions and geographic locations, webinar quality assessment, the acquisition of new knowledge and skills, the application of this newfound knowledge in practice, and the likelihood of recommending these webinars. Descriptive statistics and thematic analysis were used to analyse the quantitative and qualitative data, respectively. Ethical approval for the study was obtained.Results11,286 individuals from 107 countries participated in 18 webinars. Despite 72.7% being radiographers, a diverse array of professionals attended the webinars, including medical physicists, oncologists, radiologists, and academics. Remarkably, 98.7% of respondents rated the webinar quality as either good or excellent. The average rating for the likelihood of recommending these webinars to colleagues was 8.96/10. A substantial proportion of respondents expressed agreement or strong agreement that the webinars enhanced their knowledge (85%) and skills (73%). Furthermore, 79% of participants indicated that the webinars motivated them to change practice, with 65% having already implemented these changes. The insights from open-ended questions corroborated these findings.ConclusionThe webinars effectively achieved the aim of the SAFE EUROPE project to enhance practice by increasing knowledge and skills. Participants overwhelmingly endorsed the quality of these webinars.Implications for practiceWebinars represent a cost-efficient training tool that reaches a global audience and various radiography/radiotherapy professions. The development of additional webinars is strongly recommended.<br/

    Diet, lifestyle and body weight in Irish children: findings from Irish Universities Nutrition Alliance national surveys

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    Childhood obesity is an issue of public health concern globally. This review reports on levels of overweight and obesity in Irish children and examines some aspects of their diet and lifestyle proposed to promote or protect against increasing body fatness in children. While there is still some debate with regard to the most appropriate cut-off points to use when assessing body fatness in children, approximately one in five Irish children (aged 2–17 years) have been classified as overweight (including obese) according to two generally accepted approaches. Furthermore, comparison with previous data has shown an increase in mean body weight and BMI over time. On examining dietary patterns for Irish children, there was a noticeable transition from a less energy dense diet in pre-school children to a more energy dense diet in older children and teenagers, associated with a change to less favourable dietary intakes for fibre, fat, fruit and vegetables, confectionery and snacks and sugar-sweetened beverages as children got older. A significant proportion of school-aged children and teenagers reported watching more than 2 h television per day (35 % on school-days and 65 % on week-ends) compared with 13 % of pre-school children. For children aged 5–12 years, eating out of the home contributed just 9 % of energy intake but food eaten from outside the home was shown to contribute a higher proportion of energy from fat and to be less fibre-dense than food prepared at home. Improvements in dietary lifestyle are needed to control increasing levels of overweight and obesity in children in Ireland

    Strain dependence of bonding and hybridization across the metal-insulator transition of VO2

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    Soft x-ray spectroscopy is used to investigate the strain dependence of the metal-insulator transition of VO2. Changes in the strength of the V 3d - O 2p hybridization are observed across the transition, and are linked to the structural distortion. Furthermore, although the V-V dimerization is well-described by dynamical mean-field theory, the V-O hybridization is found to have an unexpectedly strong dependence on strain that is not predicted by band theory, emphasizing the relevance of the O ion to the physics of VO2
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