2,601 research outputs found
Measurements with the Chandra X-Ray Observatory's flight contamination monitor
NASA's Chandra X-ray Observatory includes a Flight Contamination Monitor
(FCM), a system of 16 radioactive calibration sources mounted to the inside of
the Observatory's forward contamination cover. The purpose of the FCM is to
verify the ground-to-orbit transfer of the Chandra flux scale, through
comparison of data acquired during the ground calibration with those obtained
in orbit, immediately prior to opening the Observatory's sun-shade door. Here
we report results of these measurements, which place limits on the change in
mirror--detector system response and, hence, on any accumulation of molecular
contamination on the mirrors' iridium-coated surfaces.Comment: 7pages,8figures,for SPIE 4012, paper 7
MRI-based monitoring of prostate cancer after HIFU: Inter-reader agreement and diagnostic performance of the PI-FAB score
PURPOSE: To investigate inter-reader agreement, and diagnostic performance of the Prostate Imaging after Focal Ablation (PI-FAB) score applied to multiparametric MRI (mpMRI) in patients who underwent focal high-intensity focused ultrasound (HIFU) therapy for localized prostate cancer.
METHODS: In this retrospective, IRB-approved, single-center study, 73 men, who underwent focal HIFU treatment and received follow-up mpMRIs with subsequent prostate biopsies, were included. The PI-FAB score was applied to follow-up MRIs at 6, 12, and 36 months post-HIFU by two radiologists with different experience levels. Inter-reader agreement was assessed using Gwet's AC1, and the diagnostic performance of the PI-FAB score was assessed in relation to histopathologic results of subsequent prostate biopsies for each reader.
RESULTS: PI-FAB scores showed substantial to almost perfect inter-reader agreement (AC1: 0.80-0.95) and demonstrated high specificity (Reader 1: 90-98 %, Reader 2: 87-98 %) and NPVs (Reader 1: 91-100 %, Reader 2: 88-97 %) in ruling out residual or recurrent in-field prostate cancer post-HIFU. Sensitivity (Reader 1: ≥43 %, Reader 2: ≥14 %) and PPVs (Reader 1: ≥33 %, Reader 2: ≥14 %) were mostly relatively lower, with notable disparities between the two readers, indicating the potential influence of radiologist experience.
CONCLUSIONS: The PI-FAB score provides a consistent and reliable tool for post-HIFU monitoring of prostate cancer using mpMRI. It demonstrates substantial to almost perfect inter-reader agreement and is particularly effective in excluding in-field residual or recurrent prostate cancer post-HIFU treatment. Its application can potentially enhance post-treatment patient care, emphasizing its value as a non-invasive MRI-based monitoring approach after focal ablative therapy of the prostate
An analysis of social interaction between novice older adults when learning gesture-based skills through simple digital games
This paper reports three exploratory empirical studies with older adults that had little or no prior experience with interactive technologies. The participants were introduced to interactive technology by playing games on touchscreens, playing in pairs with the assistance of a mentor. We focus on two principle aspects, the peer-to-peer interaction during these sessions, and the role of the mentor in progressing the sessions. In the case of peer-to-peer interaction we looked for ways in which players supported each other during interaction to assess the role of peer interaction in this context. In the case of mentoring, we examined the efficacy of a minimalist approach where verbal encouragement, suggestions or (in the last resort) intervention are used to provide support to learners. The sessions showed that learners typically could play and learn basic manipulations independently after initial help and guidance from mentors. We also found that peer interaction, both in verbal and non-verbal communication and cooperative action was broadly a positive influence within sessions, suggesting that there is significant value in building confidence as well as in learning
Исследование зон усталостного разрушения шнеков
Шнек - основной рабочий орган машин для переработки отходов - экструдеров. От качества его изготовления зависит производительность цеха и целостность корпуса машины. При переработке многокомпонентного сырья, которым является Refuse Derived Fuel - это общее название альтернативных видов топлива, получаемых при переработке отходов. В качестве сырья используется практически любой органический материал: целлюлоза, резина, пластик, кожа, дерево, пищевые заменители. В исследовании использован пример на базе работы с RDF-сырьем Мусороперерабатывающего комбината "Янино", Ленинградская область. Именно при работе с такими высокоабразивными отходами возникает необходимость многократно повышать ресурс шнеков за счет использования новых технологий обработки металлов, так как в составе данного сырья могут встречаться металлические компоненты и трудно размалываемые силикаты.Screw - the main working organ of machines for processing waste - extruders. From the quality of its production depends the productivity of the shop and the integrity of the machine body. When refining a multicomponent raw material, which is Refuse Derived Fuel - this is the general name for alternative fuels obtained from recycling. As raw material, almost any organic material is used: cellulose, rubber, plastic, leather, its substitutes. The study used an example based on work with RDF-raw materials of the Janino Refuse Processing Plant. Leningrad region. It is when working with such highly abrasive waste that it becomes necessary to increase the service life of screw augmentedly by using new processing technologies, since metal components and hard-to-break silicates can occur in the composition of this raw material
High-resolution x-ray telescopes
High-energy astrophysics is a relatively young scientific field, made
possible by space-borne telescopes. During the half-century history of x-ray
astronomy, the sensitivity of focusing x-ray telescopes-through finer angular
resolution and increased effective area-has improved by a factor of a 100
million. This technological advance has enabled numerous exciting discoveries
and increasingly detailed study of the high-energy universe-including accreting
(stellar-mass and super-massive) black holes, accreting and isolated neutron
stars, pulsar-wind nebulae, shocked plasma in supernova remnants, and hot
thermal plasma in clusters of galaxies. As the largest structures in the
universe, galaxy clusters constitute a unique laboratory for measuring the
gravitational effects of dark matter and of dark energy. Here, we review the
history of high-resolution x-ray telescopes and highlight some of the
scientific results enabled by these telescopes. Next, we describe the planned
next-generation x-ray-astronomy facility-the International X-ray Observatory
(IXO). We conclude with an overview of a concept for the next next-generation
facility-Generation X. The scientific objectives of such a mission will require
very large areas (about 10000 m2) of highly-nested lightweight
grazing-incidence mirrors with exceptional (about 0.1-arcsecond) angular
resolution. Achieving this angular resolution with lightweight mirrors will
likely require on-orbit adjustment of alignment and figure.Comment: 19 pages, 11 figures, SPIE Conference 7803 "Adaptive X-ray Optics",
part of SPIE Optics+Photonics 2010, San Diego CA, 2010 August 2-
Reviews and syntheses: Heterotrophic fixation of inorganic carbon – significant but invisible flux in environmental carbon cycling
Heterotrophic CO2 fixation is a significant yet underappreciated
CO2 flux in environmental carbon cycling. In contrast to photosynthesis
and chemolithoautotrophy – the main recognized autotrophic CO2
fixation pathways – the importance of heterotrophic CO2 fixation
remains enigmatic. All heterotrophs – from microorganisms to humans – take
up CO2 and incorporate it into their biomass. Depending on the
availability and quality of growth substrates, and drivers such as the
CO2 partial pressure, heterotrophic CO2 fixation contributes at
least 1 %–5 % and in the case of methanotrophs up to 50 % of the carbon
biomass. Assuming a standing stock of global heterotrophic biomass of 47–85 Pg C, we roughly estimate that up to 5 Pg C might be derived from
heterotrophic CO2 fixation, and up to 12 Pg C yr−1 originating from
heterotrophic CO2 fixation is funneled into the global annual
heterotrophic production of 34–245 Pg C yr−1. These first estimates on
the importance of heterotrophic fixation of inorganic carbon indicate that
this pathway should be incorporated in present and future carbon cycling
budgets.</p
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