المؤلفون: Jingkun Wang, Christopher Stevens, Winston Bennett, Denny Yu

المصدر: Frontiers in Neuroergonomics, Vol 5 (2024)

مصطلحات موضوعية: mental workload, mental workload modeling, physiological sensors, teleoperation task, multiple mental workload level, Neurology. Diseases of the nervous system, RC346-429

الوصف: Mental workload (MWL) is a crucial area of study due to its significant influence on task performance and potential for significant operator error. However, measuring MWL presents challenges, as it is a multi-dimensional construct. Previous research on MWL models has focused on differentiating between two to three levels. Nonetheless, tasks can vary widely in their complexity, and little is known about how subtle variations in task difficulty influence workload indicators. To address this, we conducted an experiment inducing MWL in up to 5 levels, hypothesizing that our multi-modal metrics would be able to distinguish between each MWL stage. We measured the induced workload using task performance, subjective assessment, and physiological metrics. Our simulated task was designed to induce diverse MWL degrees, including five different math and three different verbal tiers. Our findings indicate that all investigated metrics successfully differentiated between various MWL levels induced by different tiers of math problems. Notably, performance metrics emerged as the most effective assessment, being the only metric capable of distinguishing all the levels. Some limitations were observed in the granularity of subjective and physiological metrics. Specifically, the subjective overall mental workload couldn't distinguish lower levels of workload, while all physiological metrics could detect a shift from lower to higher levels, but did not distinguish between workload tiers at the higher or lower ends of the scale (e.g., between the easy and the easy-medium tiers). Despite these limitations, each pair of levels was effectively differentiated by one or more metrics. This suggests a promising avenue for future research, exploring the integration or combination of multiple metrics. The findings suggest that subtle differences in workload levels may be distinguishable using combinations of subjective and physiological metrics.

وصف الملف: electronic resource

العلاقة: https://www.frontiersin.org/articles/10.3389/fnrgo.2024.1292627/fullTest; https://doaj.org/toc/2673-6195Test

الوصول الحر: https://doaj.org/article/8afc10113b044996adb8e66074d74fc2Test

المؤلفون: Assala Aslan, Christopher Stevens, Amro Saad Aldine, Ahmed Mamilly, Luis De Alba, Octavio Arevalo, Chaitanya Ahuja, Hugo H. Cuellar

المصدر: Diagnostic and Interventional Radiology, Vol 29, Iss 3, Pp 529-534 (2023)

مصطلحات موضوعية: fragility index, interventional, radiology, rct, reproducibility you, Medical physics. Medical radiology. Nuclear medicine, R895-920

الوصف: PURPOSEThe fragility index (FI) measures the robustness of randomized controlled trials (RCTs). It complements the P value by taking into account the number of outcome events. In this study, the authors measured the FI for major interventional radiology RCTs.METHODSInterventional radiology RCTs published between January 2010 and December 2022 relating to trans-jugular intrahepatic portosystemic shunt, trans-arterial chemoembolization, needle biopsy, angiography, angioplasty, thrombolysis, and nephrostomy tube insertion were analyzed to measure the FI and robustness of the studies.RESULTSA total of 34 RCTs were included. The median FI of those studies was 4.5 (range 1–68). Seven trials (20.6%) had a number of patients lost to follow-up that was higher than their FI, and 15 (44.1%) had a FI of 1–3.CONCLUSIONThe median FI, and hence the reproducibility of interventional radiology RCTs, is low compared to other medical fields, with some having a FI of 1, which should be interrupted cautiously.

وصف الملف: electronic resource

العلاقة: http://www.dirjournal.org/archives/archive-detail/article-preview/the-reproducibility-of-interventional-radiology-ra/60194Test; https://doaj.org/toc/1305-3825Test; https://doaj.org/toc/1305-3612Test

الوصول الحر: https://doaj.org/article/32dac2ad1cac4735aa25d10d1a32c375Test

المؤلفون: Gurpreet Singh, Kyle Bennett, Lee Taylor, Christopher Stevens

المصدر: Biology of Sport, Vol 40, Iss 4, Pp 1003-1017 (2023)

مصطلحات موضوعية: hyperthermia, physiology, thermoregulation, exertional heat illness, core body temperature, Sports medicine, RC1200-1245, Biology (General), QH301-705.5

الوصف: Due to the lack of research in real-world sports competitions, the International Olympic Committee, in 2012, called for data characterising athletes’ sport and event-specific thermal profiles. Studies clearly demonstrate that elite athletes often attain a core body temperature (Tc) ≥ 40°C without heat-related medical issues during competition. However, practitioners, researchers and ethical review boards continue to cite a Tc ≥ 40°C (and lower) as a threshold where athlete health is impacted (an assumption from laboratory studies). Therefore, this narrative review aims to: (i) summarise and review published data on Tc responses during competitive sport and identify key considerations for practitioners; (ii) establish the incidence of athletes experiencing a Tc ≥ 40°C in competitive sport alongside the incidence of heat illness/heat stroke (EHI/EHS) symptoms; and (iii) discuss the evolution of Tc measurement during competition. The Tc response is primarily based on the physical demands of the sport, environmental conditions, competitive level, and athlete disability. In the reviewed research, 11.9% of athletes presented a Tc ≥ 40°C, with only 2.8% of these experiencing EHI/EHS symptoms, whilst a high Tc ≥ 40°C (n = 172; Tc range 40–41.5°C) occurred across a range of sports and environmental conditions (including some temperate environments). Endurance athletes experienced a Tc ≥ 40°C more than intermittent athletes, but EHI/EHS was similar. This review demonstrates that a Tc ≥ 40°C is not a consistently meaningful risk factor of EHI/EHS symptomology in this sample; therefore, Tc monitoring alongside secondary measures (i.e. general cognitive disturbance and gait disruption) should be incorporated to reduce heat-related injuries during competition.

وصف الملف: electronic resource

العلاقة: https://www.termedia.pl/Core-body-temperature-responses-during-competitive-sporting-events-a-narrative-review,78,50091,1,1.htmlTest; https://doaj.org/toc/0860-021XTest; https://doaj.org/toc/2083-1862Test

الوصول الحر: https://doaj.org/article/9a43d27f02684a398641f3fb1489d976Test

المؤلفون: Christopher Stevens, Kevin Malone, Amro Saad Aldine, Octavio Arevalo

المصدر: Surgical Case Reports, Vol 8, Iss 1, Pp 1-2 (2022)

مصطلحات موضوعية: Ganglioneuroblastoma, Adrenal gland, Adult onset, Surgery, RD1-811

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2198-7793Test

الوصول الحر: https://doaj.org/article/e1abe616e1e54e3da51285dd79d69b32Test

المؤلفون: Jiaruo Yan, Anna Radkovskaya, Svetlana Kiriushechkina, Irina Khromova, Christopher Stevens, Laszlo Solymar, Ekaterina Shamonina

المصدر: IEEE Open Journal of Antennas and Propagation, Vol 1, Pp 300-308 (2020)

مصطلحات موضوعية: Superdirective antennas, electromagnetic coupling, electromagnetic metamaterials, electromagnetic radiation, Telecommunication, TK5101-6720

الوصف: We propose a simple and rapid way of optimising directivity in metamaterial-inspired endfire antenna arrays with strong inter-element coupling. We introduce, in addition to the traditional 3D directivity, also its planar equivalents defined as the ratio of the power density in the desired endfire direction to the average power density calculated either in the horizontal (azimuthal) or vertical (elevation) plane. Using dimers of magnetically coupled split-ring resonators with only one element driven by an external source, we derive conditions that must be satisfied in order to realise superdirective current distributions. The superdirective conditions link the quality factor of the resonators and their coupling constant to the array size and the operating frequency. We demonstrate that a rapid measurement in the azimuthal plane can be used as a reliable indicator for whether the superdirective conditions for the 3D directivity are satisfied. Analytical calculations are verified by CST simulations in the MHz frequency range for meta-atoms of circular and square shape. Our method can be extended to arrays comprising larger number of meta-atoms of various shape and would enable rapid prototyping of 3D-printed meta-atoms with desired radiation properties.

وصف الملف: electronic resource

العلاقة: https://ieeexplore.ieee.org/document/9115046Test/; https://doaj.org/toc/2637-6431Test

الوصول الحر: https://doaj.org/article/59be8fb090f146ccba133f22dd48606fTest

المؤلفون: Christopher Stevens, Judith Horrigan, Irene Koren, Roberta Heale

المصدر: Diversity of Research in Health Journal, Vol 4, Iss 1 (2021)

مصطلحات موضوعية: Nurse, Continuing Education, E-learning, Medicine

الوصف: E-learning is a common method of continuing education for hospital staff registered nurses and there have been many studies related to the value of e-learning. However, no systematic review of studies on nurses’ e-learning could be found. An integrative review was conducted on the published literature between 2010 and 2018 on e-learning for registered nurses. The review’s goal was to systematically analyze and summarize what is known about nurses’ e-learning and elucidate where future research could explore. The final review included 21 out of 497 potential articles. Analysis revealed key themes of: Benefits of e-learning to the nurse, the patient, and the hospital, Barriers to e-learning, and Improvements for e-learning. E-learning has many suggested benefits for continuing education for registered nurses, but there are also barriers and areas for improvement. Additional research with a focus on specific jurisdictions is needed to explore how nurses perceive e-learning in specific contexts.

وصف الملف: electronic resource

العلاقة: https://pubs.biblio.laurentian.ca/index.php/drhj-rdrs/article/view/313Test; https://doaj.org/toc/2561-1666Test

الوصول الحر: https://doaj.org/article/e797bb3e7cff47cb9cab21e9e4cb6ddcTest

المؤلفون: Christopher Stevens, Hélène Dufau

المساهمون: Editions Karthala

المصدر: Politique africaine 49(1):63-81

الوصف: Les relations de la Communauté européenne avec les PVD sont fondées sur des pyramides de privilèges qui tendent à s’éroder avec l’élargissement du marché unique vers l’Est, la coordination des politiques communautaires de migrations et les difficultés des produits africains pour pénétrer l’espace européen. La communautarisation de ces relations n’est pas totalement achevée, certaines anciennes puissances colonisatrices essayant de maintenir la bilatéralité des rapports avec leurs anciennes colonies tout en faisant payer le prix à la communauté.
Economic comunity development trends : a wind of change for Africa. Relations between the EC and the PVD are founded on a pyramid of privileges which tends to erode because of the expansion of the single market towards the East; the co-ordination of common politics of migration as well as difficulties of african products to penetrate the euro-pean market. Furthermore, the relations within the community itself are not completed because ancient metropolises try to maintain narrow links with their old colonies at the expense of the EC.

الوصول الحر: https://www.persee.fr/doc/polaf_0244-7827_1993_num_49_1_5639Test

المؤلفون: Varun Mapara (12054370), Arup Barua (12054373), Volodymyr Turkowski (2071282), M. Tuan Trinh (1395133), Christopher Stevens (1737907), Hengzhou Liu (11027477), Florence A. Nugera (12054376), Nalaka Kapuruge (9155522), Humberto Rodriguez Gutierrez (12054379), Fang Liu (13271), Xiaoyang Zhu (138556), Dmitry Semenov (9419228), Stephen A. McGill (1586509), Nihar Pradhan (12054382), David J. Hilton (1835917), Denis Karaiskaj (5211512)

مصطلحات موضوعية: Biophysics, Medicine, Physiology, Biotechnology, Evolutionary Biology, Ecology, Space Science, Chemical Sciences not elsewhere classified, Physical Sciences not elsewhere classified, atomically thin semiconductors, plane energetically shift, coherent quantum beating, magnetic fields perpendicular, k ′ valleys, dark excitons relative, 2 , magnetic fields, dark excitons, plane lead, coherent dephasing, well captured, partial brightening, optical excitations, observations show, experimental results, excited simultaneously, dependent measurements

الوصف: Magnetic field- and polarization-dependent measurements on bright and dark excitons in monolayer WSe 2 combined with time-dependent density functional theory calculations reveal intriguing phenomena. Magnetic fields up to 25 T parallel to the WSe 2 plane lead to a partial brightening of the energetically lower lying exciton, leading to an increase of the dephasing time. Using a broadband femtosecond pulse excitation, the bright and partially allowed excitonic state can be excited simultaneously, resulting in coherent quantum beating between these states. The magnetic fields perpendicular to the WSe 2 plane energetically shift the bright and dark excitons relative to each other, resulting in the hybridization of the states at the K and K′ valleys. Our experimental results are well captured by time-dependent density functional theory calculations. These observations show that magnetic fields can be used to control the coherent dephasing and coupling of the optical excitations in atomically thin semiconductors.

العلاقة: https://figshare.com/articles/journal_contribution/Bright_and_Dark_Exciton_Coherent_Coupling_and_Hybridization_Enabled_by_External_Magnetic_Fields/19131340Test

الإتاحة: https://doi.org/10.1021/acs.nanolett.1c04667.s001Test

المؤلفون: Jingkun Wang, Christopher Stevens, Winston Bennett, Denny Yu

مصطلحات موضوعية: Behavioral Neuroscience, Neuroscience, Sensory Processes, Perception and Performance, Computer Perception, Memory and Attention, Neurocognitive Patterns and Neural Networks, mental workload, mental workload modeling, physiological sensors, teleoperation task, multiple mental workload level

الوصف: Mental workload (MWL) is a crucial area of study due to its significant influence on task performance and potential for significant operator error. However, measuring MWL presents challenges, as it is a multi-dimensional construct. Previous research on MWL models has focused on differentiating between two to three levels. Nonetheless, tasks can vary widely in their complexity, and little is known about how subtle variations in task difficulty influence workload indicators. To address this, we conducted an experiment inducing MWL in up to 5 levels, hypothesizing that our multi-modal metrics would be able to distinguish between each MWL stage. We measured the induced workload using task performance, subjective assessment, and physiological metrics. Our simulated task was designed to induce diverse MWL degrees, including five different math and three different verbal tiers. Our findings indicate that all investigated metrics successfully differentiated between various MWL levels induced by different tiers of math problems. Notably, performance metrics emerged as the most effective assessment, being the only metric capable of distinguishing all the levels. Some limitations were observed in the granularity of subjective and physiological metrics. Specifically, the subjective overall mental workload couldn't distinguish lower levels of workload, while all physiological metrics could detect a shift from lower to higher levels, but did not distinguish between workload tiers at the higher or lower ends of the scale (e.g., between the easy and the easy-medium tiers). Despite these limitations, each pair of levels was effectively differentiated by one or more metrics. This suggests a promising avenue for future research, exploring the integration or combination of multiple metrics. The findings suggest that subtle differences in workload levels may be distinguishable using combinations of subjective and physiological metrics.

العلاقة: https://figshare.com/articles/dataset/Data_Sheet_1_Granular_estimation_of_user_cognitive_workload_using_multi-modal_physiological_sensors_docx/25294531Test

الإتاحة: https://doi.org/10.3389/fnrgo.2024.1292627.s001Test
https://figshare.com/articles/dataset/Data_Sheet_1_Granular_estimation_of_user_cognitive_workload_using_multi-modal_physiological_sensors_docx/25294531Test

المؤلفون: Elizabeth Fox, Arielle Stephenson, Christopher Stevens, Gregory Bowers

المصدر: International Conference on Cyber Warfare and Security. 18:93-102

الوصف: Aegis operators simultaneously locate and monitor the activity of several hostile targets, intervening and alerting their team when appropriate. Utilizing the Aegis Combat System, operators find, track, and respond to dynamic targets on a radar screen. The demand that operators undergo is often high, inevitably causing strain on cognitive functions and detriments to performance. We applied model-based measures, Cost and Multitasking Throughput, to quantify the influence of external factors on processing efficiency in radar task(s). We captured the influence of three experimental manipulations, each of three levels, on human efficiency to track the location of hostiles and/or detect brief radar interference. We collected participants’ performance to complete a multiple object tracking (MOT) task and an electronic attack detection task (EA) using a radar display. A factorial manipulation of conditions comprised changes to task(s) (EA, MOT, or both), the number of targets to track (2, 4, or 6) and the presence or absence of distractors, deemed 'friendlies' (between 500-1000 total tracks). Our novel individual- and model-based approach provided quantitative estimates of human efficiency. We compared the observed variation in efficiency among predictors including target quantity, visual load, and the presence of one or two interrelated tasks. Through quantifying the relationship of these variables to radar detection tasks, we discuss implications of our findings and provide a framework to examine how system designers may develop tools to alleviate observed cognitive demands and/or counter potential threats of electronic attacks in radar detection and tracking tasks.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::967cf2a2f499da5a5574ca7563d41a66Test
https://doi.org/10.34190/iccws.18.1.976Test