Performance of three-photon PET imaging: Monte Carlo simulations

We have recently introduced the idea of making use of three-photon positron annihilations in positron emission tomography. In this paper the basic characteristics of the three-gamma imaging in PET are studied by means of Monte Carlo simulations and analytical computations. Two typical configurations of human and small animal scanners are considered. Three-photon imaging requires high energy resolution detectors. Parameters currently attainable by CdZnTe semiconductor detectors, the technology of choice for the future development of radiation imaging, are assumed. Spatial resolution is calculated as a function of detector energy resolution and size, position in the field of view, scanner size, and the energies of the three gamma annihilation photons. Possible ways to improve the spatial resolution obtained for nominal parameters: 1.5 cm and 3.2 mm FWHM for human and small animal scanners, respectively, are indicated. Counting rates of true and random three-photon events for typical human and small animal scanning configurations are assessed. A simple formula for minimum size of lesions detectable in the three-gamma based images is derived. Depending on the contrast and total number of registered counts, lesions of a few mm size for human and sub mm for small animal scanners can be detected

Building Cognition-Aware Systems: A Mobile Toolkit for Extracting Time-of-Day Fluctuations of Cognitive Performance

People’s alertness fluctuates across the day: at some times we are highly focused while at others we feel unable to concentrate. So far, extracting fluctuation patterns has been time and cost-intensive. Using an in-the-wild approach with 12 participants, we evaluated three cognitive tasks regarding their adequacy as a mobile and economical assessment tool of diurnal changes in mental performance. Participants completed the five-minute test battery on their smartphones multiple times a day for a period of 1-2 weeks. Our results show that people’s circadian rhythm can be obtained under unregulated non-laboratory conditions. Along with this validation study, we release our test battery as an open source library for future work towards cognition-aware systems as well as a tool for psychological and medical research. We discuss ways of integrating the toolkit and possibilities for implicitly measuring performance variations in common applications. The ability to detect systematic patterns in alertness levels will allow cognition-aware systems to provide in-situ assistance in accordance with users’ current cognitive capabilities and limitations

Stoffaustrag und Bodenbearbeitung

Der vorliegende Bericht stellt Ergebnisse des zweijährigen Projektes 'Veränderte Pflanzenschutzmittel- und Nährstoffausträge bei bodenschonender Bewirtschaftung - Risikoanalyse und -vorsorge' vor. Auf landwirtschaftlichen Flächen in der Lommatzscher Pflege wurden mit einer Beregnungsanlage Starkniederschläge (worst-case-Szenario) simuliert. Die Untersuchungen zu Wasser- und Agrochemikalientransport fanden auf Flächen statt, die konventionell mit Pflug, konservierend flach bearbeitet bzw. in Direktsaat bestellt wurden. Die Auswirkungen auf vertikale und horizontale Stofftransporte, insbesondere von Nitrat-Stickstoff und dem Totalherbizid Durano mit dem Wirkstoff Glyphosat wurden untersucht

The Consistency of Crossmodal Synchrony Perception across the Visual, Auditory, and Tactile Senses

Machulla T-K, Di Luca M, Ernst MO. The Consistency of Crossmodal Synchrony Perception across the Visual, Auditory, and Tactile Senses. Journal of Experimental Psychology: Human Perception and Performance. 2016;42(7):1026-1038

Convergence of technologies as a basis for technological transitionon

It is shown that convergence of technologies plays a key role in the development of a new technological transition. The essence of technological convergence and processing of functions of the modern stage of its development is considered. The content of NBIC-convergence and NBICS-convergence is disclosed. It is revealed that information technologies are dominant in the structure of technological convergence. The identified positive and negative effects of the spread of convergent technologies. Special attention is paid to the problem of technology transfer

Pretreatment 18F-FAZA PET Predicts Success of Hypoxia-Directed Radiochemotherapy Using Tirapazamine

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Significant impact of different oxygen breathing conditions on noninvasive in vivo tumor-hypoxia imaging using [18F]-fluoro-azomycinarabino-furanoside ([18F]FAZA)

<p>Abstract</p> <p>Background</p> <p>[¹⁸F]FAZA is a PET biomarker with great potential for imaging tumor hypoxia. Aim of our study was to compare [¹⁸F]FAZA uptake in mice with subcutaneous exogenous CT26 colon carcinomas and endogenous polyoma middle-T (PyV-mT) mammary carcinomas and to analyze the influence of different breathing protocols in CT26 colon carcinomas as well as the reversibility or irreversibility of [¹⁸F]FAZA uptake.</p> <p>Methods</p> <p>We injected subcutaneous CT26 colon carcinoma or polyomavirus middle-T (PyV-mT) mammary carcinoma-bearing mice intravenously with¹⁸F-FAZA and performed PET scans 1-3 h post injection (<it>p.i.</it>). To analyze the impact of oxygen supply in CT26 carcinomas we used three different breathing protocols: (P0) air; (P1) 100% oxygen 1 h prior injection until 3 h <it>p.i.</it>; (P2) 100% oxygen breathing starting 2 min prior tracer injection until 1 h <it>p.i. </it>and during the PET scans; mice were breathing air between the 2 h and 3 h 10 min static scans. Normalized PET images were analyzed by using defined regions of interest. Finally, some mice were dissected for pimonidazole immunohistochemistry.</p> <p>Results</p> <p>There was no difference in¹⁸F-FAZA uptake 1-3 h <it>p.i. </it>between the two carcinoma types (CT26: 1.58 ± 0.45%ID/cc; PyV-mT: 1.47 ± 0.89%ID/cc, 1 h <it>p.i.</it>, tumor size < 0.5 cm³). We measured a significant tracer clearance, which was more pronounced in muscle tissue (P0). The [¹⁸F]FAZA tumor-to-muscle-ratios in CT26 colon carcinoma-bearing mice 2 h and 3 h, but not 1 h <it>p.i. </it>were significantly higher when the mice breathed air (P0: 3.56 ± 0.55, 3 h) compared to the oxygen breathing protocols (P1: 2.45 ± 0.58; P2: 2.77 ± 0.42, 3 h). Surprisingly, the breathing protocols P1 and P2 showed no significant differences in T/M ratios, thus indicating that the crucial [¹⁸F]FAZA uptake phase is during the first hour after [¹⁸F]FAZA injection. Importantly, the muscle clearance was not affected by the different oxygen breathing conditions while the tumor clearance was lower when mice were breathing air.</p> <p>Conclusion</p> <p>Exogenous CT26 colon carcinomas and endogenous polyoma middle-T (PyV-mT) mammary carcinomas showed no differences in [¹⁸F]FAZA uptake 1-3 h <it>p.i. </it>Our analysis using various breathing protocols with air (P0) and with pure oxygen (P1, P2) clearly indicate that [¹⁸F]FAZA is an appropriate PET biomarker for <it>in vivo </it>analysis of hypoxia revealing an enhanced tracer uptake in tumors with reduced oxygen supply. [¹⁸F]FAZA uptake was independent of tumor-type.</p

Таможенные услуги: сущность, порядок предоставления и проблемы качества

В работе исследуется содержание системы предоставления таможенных услуг в России. Также в работе представлены результаты изучения качества предоставления таможенных услуг таможенными органами и коммерческим сектором и предлагаются пути решения данных проблем.The diploma work is aimed at studying the content of the system of providing customs services in Russia. The diploma work also studies the problem of the quality of services provided by the customs authorities and the commercial sector and suggests the ways of its solving