34 research outputs found
In vivo reporter gene imaging of herpes simplex virus-1 thymidine kinase using SPECT/CT and radiolabeled FIAU
No full textSolution Space-based Approach to Assess Sector Complexity in Air Traffic Control
No full textVarious methods have been introduced in the past in efforts to optimize airspace sector design and the allocation of air traffic controllers. This is done with the aim to accommodate growth, increase productivity and most importantly to ensure safety of air traffic. To accomplish this, a more comprehensive understanding of human workload, especially that of the controllers involved, is required. In Air Traffic Control (ATC), there exists a maximum number of aircraft per sector that the Air Traffic Controller (ATCO) is assumed to be capable of controlling simultaneously. The maximum controllable traffic is gathered based on experimentation and subjective assessments of controller workload, which are sector specific. This threshold is not to be exceeded in order to maintain a reasonable and sustainable level of workload. However, a sector complexity metric based on the maximum number of aircraft does not consider the dynamic nature of air traffic, thus limiting the possibility of accommodating the growth of air traffic. Consequently, to better support strategic decisions that need information on ATC workload, we need better measures than just the number of aircraft. Metrics, for example the Dynamic Density (DD) that use a weighted combination of static and dynamic airspace properties, such as the number of aircraft flying through a sector, the ratio of climbing, cruising and descending aircraft, the horizontal proximity between aircraft et cetera, have been constructed and proposed as a sector complexity measure. The proposed weightings are determined through regression analysis on expert judgement for a particular sector design. As a result, these metrics become highly dependent on sector and operator-centered factors and therefore not uniformly applicable to a wider range of operators and sector designs. A careful calibration would then be needed to tailor the measure to each individual operator and also to the considered sector. In an effort to find a more objective measure of sector complexity and a predictor of workload, this thesis investigates a constraint-based measure based on the Solution Space Diagram (SSD). In essence, the SSD is a method to observe aircraft restrictions and opportunities to resolve air traffic conflicts in both the speed and heading dimensions. The SSD can be described as the available control area for the controlled aircraft in respect to other observed aircraft within the vicinity. The construction of the SSD is based on the projection of the ‘zone of conflict’ of the observed aircraft where the key constraint is the 5 NM separation minimum between aircraft. When considering the SSD for any individual aircraft, all neighboring aircraft introduce a ‘no-go area’ or ‘zone of conflict’ on the SSD. Intrusion of this zone is called a conflict, or, loss of separation. Looking at the results of the numerous off-line and real-time human-in-the-loop experiments, the proposed SSD metric shows a promising prospect of being an objective measure of sector complexity and a viable subjective workload predictor. However, these results are based on specific experiment settings, assumptions, and simplifications that were made throughout the research. Thus, to prove that the method was found to be the most suited metric in measuring sector complexity, a more extensive research regarding its performance and robustness should be done in the future. More comprehensive research on sector complexity has to be done in order to have a better understanding of sector complexity and controller workload. Also, to keep up with the relevance of the current situation, the extension of the SSD to the third dimension is crucial.Control and SimulationAerospace Engineerin
Correction for Rando et al., “Pathogenesis, Symptomatology, and Transmission of SARS-CoV-2 through Analysis of Viral Genomics and Structure”
No full textVolume 6, no. 5, e00095-21, 2021, https://doi.org/10.1128/mSystems.00095-21. The author byline and affiliations should appear as shown in this correction. Page 3: The following should be added to the Fig. 1 legend. ‘This figure was adapted from “Human Coronavirus Structure,” by BioRender.com (2020), retrieved from https://app .biorender.com/biorender-templates.’ Page 21: In the 2nd paragraph of Acknowledgements, “S.M.B. is currently an employee at AstraZeneca, Gaithersburg, MD, USA, and may own stock or stock options; work was initially conducted at Georgetown University Medical Center, with writing, reviewing, and editing continued while working at AstraZeneca. Y.P. is now employed by Pfizer (subsequent to contributions to this project).” should read “S.M.B. is currently an employee at AstraZeneca, Gaithersburg, MD, USA, and may own stock or stock options. Y.P. is affiliated with Pfizer Worldwide Research; the author has no financial interests to declare and contributed as an author prior to joining Pfizer, and the work was not part of a Pfizer collaboration nor was it funded by Pfizer.” Copyright © 2022 Rando et al
Lead Composite Vs. Nonlead Protective Garments: Which Are Better? A Multivendor Comparison
No full textContains fulltext :
177795.pdf (Publisher’s version ) (Closed access)This study aims to provide more insight in attenuation characteristics and corresponding lead (Pb) equivalences of a broad range of commercially available lead composite and nonlead protective garments. Thirty garments of five manufacturers (listed as 0.25-0.35-0.50 mm Pb equivalent) were tested. Transmission values were determined at 70, 90 and 110 kVp using an inverse broad beam geometry. Pb equivalence was determined using lead sheets as reference material. A substantial variability in photon transmission across garments was found. Differences between lead composite and nonlead garments were not statistically significant. Depending on tube voltage, between 9 and 12 out of 30 garments had a lower Pb equivalence than the indicated value. This work shows that lead equivalence as indicated on a garment's label may overestimate its protective performance. Depending on the application a more thorough verification of the effectiveness of protective garments at the desired kVp is warranted
Cross-sector transferability of metrics for air traffic controller workload
No full textAir traffc controller workload is an important impediment to air transport growth. Several approaches exist that aim to better understand the causes for workload, and models have been derived to predict workload in new operational settings. These methods often relate workload to the diffculty, or complexity, that an average controller would have to safely manage all traffc in a sector with a particular traffc demand. In this paper, several of these complexity-based metrics for workload will be compared. Of special interest is whether the complexity measures transfer from one sector design to another. That is, does a metric that is well-tuned to predict workload for controllers working in one sector, also predict the workload for another group of controllers active in a different sector? Results from a human-in-the-loop experiment show that a solution space-based metric, which requires no tuning or weighing at all, has the highest correlations with subjectively reported workload, and also yields the best workload predictions across different controller groups and sectors
Measuring Sector Complexity: Solution Space-Based Method
No full textControl and OperationsAerospace Engineerin
Using the Solution Space Diagram in Measuring the Effect of Sector Complexity During Merging Scenarios
No full textWhen designing Air Traffic Control (ATC) sectors and procedures, traffic complexity and workload are important issues. For predicting ATC workload, metrics based on the Solution Space Diagram (SSD) have been proposed. This paper studies the effect of sector design on workload and SSD metrics. When considering the SSD in evaluation of a sector, each aircraft within the sector introduces a zone of conflict, the Forbidden Beam Zone (FBZ), on the SSD. The properties of these FBZ are systematically studied to increase understanding of the SSD usability in assessing workload and sector complexity. The effects of sector design variables on Air Traffic Controller (ATCo) workload and also SSD properties were evaluated. Example of sector properties are, number of streams to be merged, the merge angle, the proximity of incoming aircraft and the variability of traffic mix of small and large aircraft. Based on the findings, each sector design variable leads to different effect on both workload and SSD properties. Apart from that, correlation between the workload and the SSD properties were found to be in a higher level than of the number of aircraft within the sector, proving that the SSD-based analysis to be a good workload indicator. These correlations were studied based on two different groups of subjects with ranging experience in order to demonstrate the robustness of the method.Control & OperationsAerospace Engineerin
ORGAN EQUIVALENT DOSE AND LIFETIME ATTRIBUTABLE RISK OF CANCER INCIDENCE AND MORTALITY ASSOCIATED WITH CARDIAC CT ANGIOGRAPHY
No full textThe aim of this study is the calculation of equivalent organ dose and estimation of lifetime attributable risk (LAR) of cancer incidence and mortality related to cardiac computed tomography angiography (CCTA) because the use of CT angiography as a noninvasive diagnostic method has increased. The organ dose has been calculated by ImPACT software based on the volumetric CT dose index (CTDIvol), and LAR of cancer risk incidence and mortality from CCTA has estimated according to the BEIR VII report. The median value of the effective dose was 13.78 ± 6.88 mSv for both genders. In all scanners, the highest median value for LAR of cancer incidence in males and females for lung cancer was 44.20 and 109.17 per 100 000, respectively. And in infants was 5.89 and 12 for lung cancer in males and breast cancer in females, respectively. Also, the median value of LAR of all cancer incidence from single CCTA in adult patients for males and females was 122 and 238 cases, respectively. Maximum LAR of cancer mortality in adults for lung cancer was 40.28 and 91.84 and in pediatrics was 5.69 and 8.50 in males and females, respectively. Despite many benefits of CTA in the heart disease evaluation, according to a high radiation dose in CCTA, to reduce the cancer risk: CCTA should be used cautiously, especially for pediatric and females. © The Author(s) 2020. Published by Oxford University Press. All rights reserved. For Permissions, please email: [email protected]
