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| 6. |
- Ash, G. I., et al.
(författare)
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Establishing a Global Standard for Wearable Devices in Sport and Exercise Medicine: Perspectives from Academic and Industry Stakeholders
- 2021
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Ingår i: Sports Medicine. - : Springer Science and Business Media LLC. - 0112-1642 .- 1179-2035. ; 51, s. 2237-2250
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Tidskriftsartikel (refereegranskat)abstract
- Millions of consumer sport and fitness wearables (CSFWs) are used worldwide, and millions of datapoints are generated by each device. Moreover, these numbers are rapidly growing, and they contain a heterogeneity of devices, data types, and contexts for data collection. Companies and consumers would benefit from guiding standards on device quality and data formats. To address this growing need, we convened a virtual panel of industry and academic stakeholders, and this manuscript summarizes the outcomes of the discussion. Our objectives were to identify (1) key facilitators of and barriers to participation by CSFW manufacturers in guiding standards and (2) stakeholder priorities. The venues were the Yale Center for Biomedical Data Science Digital Health Monthly Seminar Series (62 participants) and the New England Chapter of the American College of Sports Medicine Annual Meeting (59 participants). In the discussion, stakeholders outlined both facilitators of (e.g., commercial return on investment in device quality, lucrative research partnerships, and transparent and multilevel evaluation of device quality) and barriers (e.g., competitive advantage conflict, lack of flexibility in previously developed devices) to participation in guiding standards. There was general agreement to adopt Keadle et al.'s standard pathway for testing devices (i.e., benchtop, laboratory, field-based, implementation) without consensus on the prioritization of these steps. Overall, there was enthusiasm not to add prescriptive or regulatory steps, but instead create a networking hub that connects companies to consumers and researchers for flexible guidance navigating the heterogeneity, multi-tiered development, dynamicity, and nebulousness of the CSFW field.
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| 7. |
- Smith, P B, et al.
(författare)
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Cultural values, sources of guidance, and their relevance to managerial behavior - A 47-nation study
- 2002
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Ingår i: Journal of Cross-Cultural Psychology. - : Sage Publications. - 0022-0221 .- 1552-5422. ; 33:2, s. 188-208
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Tidskriftsartikel (refereegranskat)abstract
- Data are presented showing how middle managers in 47 countries report handling eight specific work events. The data are used to test the ability of cultural value dimensions derived from the work of Hofstede. Trompenaars, and Schwartz to predict the specific sources of guidance on which managers rely. Focusing on sources of guidance is expected to provide a more precise basis than do generalized measures of values for understanding the behaviors that prevail within different cultures. Values are strongly predictive of reliance on those sources of guidance that are relevant to vertical relationships within organizations. Hock ever, values are less successful in predicting reliance on peers and on more tacit sources of guidance. Explaining national differences in these neglected aspects of organizational processes will require greater sensitivity to the culture-specific contexts within which they occur.
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| 8. |
- Mortazavi, S. M. J., et al.
(författare)
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Does Exposure of Astronauts' Brains to High-LET Radiation in Deep Space Threaten the Success of the Mission?
- 2020
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Ingår i: 2020 IEEE AEROSPACE CONFERENCE (AEROCONF 2020). - 1095-323X. - 9781728127347
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Konferensbidrag (refereegranskat)abstract
- Astronauts' exposure to radiation is different from exposure to radiation on Earth. Besides cancer, cardiovascular disease and acute radiation syndrome, there are concerns over the potential behavioral and cognitive impairments caused by exposure of the astronauts' central nervous system to high levels of space radiation. Therefore, potential behavioral and cognitive i mpairments caused by astronauts' brains exposure to high levels of space radiation and the possibility of developing dementia and other motor neuron diseases are getting more attention. As NASA is interested in studies on radium deposition in human brain, and exposure of the brain to high linear energy transfer (LET) alpha particles, we have assessed the cognitive effects of long-term exposure of human brain to alpha particles which partly mimics astronauts' exposure to high charge and energy (HZE) particles during upcoming mars missions. Dr. John Boice, President of NCRP, and his colleagues' have stated that human brain exposed for years to alpha particles on Earth may be more relevant to a Mars mission in contrast with the mouse brain exposed to heavy ions for a few minutes. Interestingly, both Boice and NASA did not pay enough attention to this fact that radium as well as many other alpha emitters tend to accumulate in the bone, and the alpha particles whose energies are typically -5 MeV have a very short range (maximum lOs of um), so the radiation dose due to the alpha emitters would be localized to volumes near the cranium rather than being uniformly distributed throughout the cerebral and cerebellar parenchyma. Extraordinary high levels of Ra-226 have previously been reported in high background radiation areas of Ramsar, where people are consuming locally grown foods. In this paper, we will present data which provide a human brain radiation exposure analogue for upcoming Mars missions. Normally the dose to the functional parts of the brain are not likely to be significant, even with higher uptakes of the radium or other alpha-emitting isotopes in the cranium. Therefore, only residents with calcium-rich diet were selected for the study. Measurements of background gamma radiation was performed in their bedrooms, dining rooms, vegetable yards and gardens with citrus fruit trees of the dwellings in areas with high levels of Ra-226 in the soil and at a nearby control area with the same socio-economic factors. Moreover, the food frequency, reaction time, working memory and computational abilities as well as the Radium Ingestion Index (RII) of 47 participants (22 males and 24 females) from the hot areas, where the annual radiation absorbed dose from background radiation is up to 260 mSv/y, were studied, and the same things were studied for 17 participants (4 males and 13 females) from a nearby normal background radiation area with the same socioeconomic factors as at the hot areas. Our study showed that exposure of human brain to high LET particles did not affect the working memory. However, individuals with higher levels of radium ingestion had significantly increased reaction times. The increased reaction time in individuals with higher exposure levels to alpha particles emitted from ingested Ra-226 is an important finding, since similar conditions might occur in deep space, when astronauts' brain cells are exposed to HZE particles. As the astronauts face numerous challenges in isolated and confined space environment, they should be able to respond quickly to different hazards. However, further studies are needed to verify if the fmdings in high radiation dose areas in Ramsar are relevant for deep space mission.
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| 11. |
- Mortazavi, S. A.R., et al.
(författare)
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Can Reactivation of SARS-CoV-2 Decrease the Chance of Success of Future Deep Space Missions?
- 2021
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Ingår i: IEEE Aerospace Conference Proceedings. - 1095-323X. ; 2021-March
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Konferensbidrag (refereegranskat)abstract
- Korean CDC experts first reported the likelihood of reactivation in COVIOD-19 patients. They hypothesized that like childhood chicken pox infections which lie dormant for tens of years only to cause shingles in seniors, SARS-CoV-2 can reactivate. However, as testing for the virus had been flawed at that time, U.S. infectious disease experts were skeptical about the reports of second COVID-19 infections. New reports have addressed the urgent need to conduct large-scale studies to better understand the potential recurrence of SARS-CoV-2 in COVID-19 patients. Moreover, some case studies show possible reactivation of SARS-CoV-2 in a family cluster. Given this consideration, major space stressors such as microgravity and space radiation and their interactions which are not fully known, so far can increase the risk of reactivation of SARS-CoV-2 in future space missions, an event that can easily impact the success of any space mission. Since about 80% of infected people are either asymptomatic or show only mild symptoms, in a near future, it would be likely that astronauts who start their mission even after complex medical examinations, experience reactivation of the virus during their mission. Moreover, we have previously addressed the potential higher fatality of COVID-19 infections in space due to 1) uselessness of social distancing due to microgravity 2) immune system dysregulation 3) possibly higher mutation rates of the novel coronavirus (SARS-CoV-2) as a RNA virus 4) higher risk of reactivation of the virus 5) existence of strong selective pressure and 6) decreased maximum oxygen uptake.
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| 12. |
- Mortazavi, S. M. J., et al.
(författare)
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Radioadaptation of Astronauts' Microbiome and Bodies in a Deep Space Mission to Mars and Beyond
- 2020
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Ingår i: 2020 IEEE AEROSPACE CONFERENCE (AEROCONF 2020). - 1095-323X. - 9781728127347
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Konferensbidrag (refereegranskat)abstract
- During manned space missions, humans will be accompanied by microorganisms. This prompts us to study the characteristics of bacteria grown in space [1]. It has been shown that a pre-exposure to low levels of either ionizing or non-ionizing radiation can make microorganisms more resistant not only to high doses of ionizing radiation but to any factor that threatens their survival (e.g. antibiotics) [2,3]. This phenomenon that is called "adaptive response" (i.e. increased resistance in living organisms pre-exposed to a low level stressor such as a low dose of ionizing radiation) [4] significantly increases the risk of serious infections in deep space missions. It's worth noting that both animal and human data confirm the disruption of the immune system during spaceflight [5]. In addition, the virulence of bacteria can also be increased significantly in space [4], hence this kind of adaptive response which increases the resistance of bacteria can endanger the astronauts' lives in space. On the other hand, A NASA report notes that as astronauts' cells will be exposed to multiple protons before being traversed by HZE particles, they can show adaptive responses. Given this consideration, it would be realistic to expect co-radioadaptation of astronauts' microbiome and their body in a deep space journey to Mars and beyond. The complexity of these phenomena and current uncertainties, which highlight the need for further studies before any long-term manned mission, will be discussed in this paper.
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| 13. |
- Esmaily, M., et al.
(författare)
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A detailed microstructural and corrosion analysis of magnesium alloy WE43 manufactured by selective laser melting
- 2020
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Ingår i: Additive Manufacturing. - : Elsevier BV. - 2214-8604. ; 35
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Tidskriftsartikel (refereegranskat)abstract
- The production of magnesium alloy WE43 was achieved by selective laser melting (SLM). The alloy was investigated after SLM, hot isostatic pressing (HIP), and solutionising heat treatment. The microstructure and corrosion behaviour of the specimens were carefully characterised, whilst assessed and contrast relative to the conventionally cast alloy counterpart. The SLM prepared specimens possess a unique microstructure comprising fine grains growing with a strong [0001] texture along the building direction with a low fraction of process-induced and metallurgical defects, reaching < 0.1 %, after optimising the SLM parameters and the HIP treatment. Electrochemical measurements demonstrated that the SLM prepared WE43 is cathodically more active as compared with its cast counterpart. It is proposed that this behaviour is due to a high density of zirconium-rich oxide particles uniformly distributed throughout the alloy microstructure as well as the alterations in the chemical composition of the solid-solution matrix originating from the high cooling rates of SLM. It was also noted that the oxide particles are mainly sourced by powder. The present results suggest that the corrosion of SLM prepared Mg alloys could be greatly improved once the influence of powder characteristics is further understood and controlled.
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| 14. |
- Kazemi, E., et al.
(författare)
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The effect of superposition of 900 MHz and incoherent noise electromagnetic fields on the induction of reactive oxygen species in SP2/0 cell line
- 2015
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Ingår i: International journal of radiation research. - 2322-3243. ; 13:3, s. 275-280
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Tidskriftsartikel (refereegranskat)abstract
- Background: Induction of cellular response after exposure to electromagnetic fields is limited to coherent fields. An incoherent noise field is supposed to suppress the bioeffects of regular RF electromagnetic fields. The purpose of this study was to investigate the effect of GSM mobile phone-induced radiofrequency (RF) on the induction of oxidative stress in SP2/0 cell line. Materials and Methods: This study was also an attempt to assess whether these RF-induced effects can be blocked by superposing the RF radiation and an incoherent magnetic noise. Three groups of cultured cells were used in this study. The cells in the first group were only exposed to RF radiation emitted from a mobile phone simulator. The second group was only exposed to an incoherent noise field and the third group was simultaneously exposed to RF radiation and incoherent noise field. The exposure duration in all groups was 2 hours. The level of ROS production in the cells was quantified by the CM-H2DCFDA fluorescence probe, using flow cytometry technique. Results: Although our results showed increased ROS production after exposure to 900 MHz RF radiation, superposition of 900 MHz RF and the incoherent noise fields did not lead to increased levels of ROS in any experiment. However, the differences between RF exposure group and superposition of RF and noise exposure group were not statistically significant. Conclusion: Altogether our results cannot support the neutralizing effect of noise theory but may confirm the concept that just the coherent fields can be bioeffective while the incoherent noise fields cannot cause any biological effects.
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| 15. |
- Mortazavi, S. M. J., et al.
(författare)
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Can Adaptive Response and Evolution Make Survival of Extremophile Bacteria Possible on Mars?
- 2020
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Ingår i: 2020 IEEE AEROSPACE CONFERENCE (AEROCONF 2020). - 1095-323X. - 9781728127347
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Konferensbidrag (refereegranskat)abstract
- The humidity on the surface of the red planet, Mars, drops steeply during the daytime as the temperature rises. In this situation, Martian microorganisms should have the capability to cope with desiccation. Extremophiles are microorganisms that are capable of surviving in extreme environmental conditions. It has previously been shown that a pre-exposure to low levels of either ionizing or non-ionizing radiation can induce resistance against subsequent exposure to high levels of different stressors (e.g. high doses of ionizing radiation) in a wide variety of living systems. Moreover, it has been shown that E. coli bacteria repeatedly exposed to a dose needed for 1% survival, and increasing the dose each time due to increased radioresistance for the same survival (1%), generates extremely radioresistant bacteria through directed evolution. Mortazavi et al. have warned that in a similar manner with extremophiles such as Deinococcus radiodurans, it would be very likely that this type of human-directed radioresistance makes E. coli bacteria resistant to all physical and chemical agents (generation of serious life-threatening micro-organisms). There are reports about the possibility of the existence of microbes in the salty puddles of Mars. On Mars, with its thin atmosphere and lack of the protective magnetic field, higher levels of space radiation cause more genetic mutations. Interestingly, these mutations in bacteria, which can make them resistant against radiation, can also make them resistant against desiccation. Moreover, the adaptive response to radiation in bacteria might play an important role in this process. As stated in a NASA report, the cells in the astronauts will be traversed by multiple protons before exposure to HZE particles. This sequential exposure might significantly increase the resistance against radiation. The same exposure in bacteria might not only induce resistance against the high levels of damage caused by HZEs, but also to other life-threatening factors for bacteria such as desiccation. In this paper, the current understanding of extremophiles and their capability of surviving in extreme environmental conditions as well as current findings about radioadaptive responses in bacteria will be discussed.
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| 21. |
- Gomez-Cabrero, D, et al.
(författare)
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STATegra, a comprehensive multi-omics dataset of B-cell differentiation in mouse
- 2019
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Ingår i: Scientific data. - : Springer Science and Business Media LLC. - 2052-4463. ; 6:1, s. 256-
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Tidskriftsartikel (refereegranskat)abstract
- Multi-omics approaches use a diversity of high-throughput technologies to profile the different molecular layers of living cells. Ideally, the integration of this information should result in comprehensive systems models of cellular physiology and regulation. However, most multi-omics projects still include a limited number of molecular assays and there have been very few multi-omic studies that evaluate dynamic processes such as cellular growth, development and adaptation. Hence, we lack formal analysis methods and comprehensive multi-omics datasets that can be leveraged to develop true multi-layered models for dynamic cellular systems. Here we present the STATegra multi-omics dataset that combines measurements from up to 10 different omics technologies applied to the same biological system, namely the well-studied mouse pre-B-cell differentiation. STATegra includes high-throughput measurements of chromatin structure, gene expression, proteomics and metabolomics, and it is complemented with single-cell data. To our knowledge, the STATegra collection is the most diverse multi-omics dataset describing a dynamic biological system.
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| 23. |
- Khodabakhshi, A., et al.
(författare)
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Effects of cold working and heat treatment on microstructure and wear behaviour of Cu–Be alloy C17200
- 2015
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Ingår i: Tribology - Materials, Surfaces and Interfaces. - : Informa UK Limited. - 1751-584X .- 1751-5831. ; 9:3, s. 118-127
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Tidskriftsartikel (refereegranskat)abstract
- © 2015 Institute of Materials, Minerals and Mining and W. S. Maney & Son Ltd. The effects of cold work process between aging and solution heat treatment on the microstructure, hardness and the tribologic behaviour of a copper–beryllium (Cu–Be) alloy C17200 were investigated. The wear behaviour of the alloys was studied using ‘pin on disc’ method under dry conditions. The results show that the formation of fine grained structure and γ phase particles enhances the mechanical properties of the alloy; nonetheless, they do not reduce the wear rate. This is attributed to the capability of the softer specimens to maintain oxygen rich compounds during the dry sliding test.
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| 25. |
- Najafi, F., et al.
(författare)
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Overcoming fear of movement resulting from knee replacement; strategies used by patients: An interview study
- 2022
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Ingår i: International Journal of Orthopaedic and Trauma Nursing. - : Elsevier BV. - 1878-1241 .- 1878-1292. ; 45
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Tidskriftsartikel (refereegranskat)abstract
- Background and aims: Fear of movement is among the main concerns of patients following knee replacement surgery and a determining factor in the success of surgery. The strategies adopted by patients to overcome this fear have not yet been identified, but once pin pointed, these strategies can be strengthened and modified through intervention. The aim of the present study was to explore the personal strategies adopted by patients following knee replacement to overcome fear of movement. Materials and methods: Interviews were conducted with 15 patients who had undergone knee replacement, selected by purposive sampling. Data were collected through in-depth semi-structured interviews and analyzed using inductive content analysis. Results: The patients’ strategies as depicted in their narratives were classified into three categories: 1) Movement based on awareness; 2) Movement based on support; and 3) Movement based on hope. These three categories are described in eight subcategories and show what strategies the patients used to overcome their fear of movement. Conclusion: These findings can help to increase awareness about strategies to overcome fear of movement in patients following knee replacement and to develop and support tailored treatment strategies with the aim of reducing such fear of movement and increasing physical activity among the patients. © 2021 Elsevier Ltd
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| 28. |
- Sangha, Veer, et al.
(författare)
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Detection of Left Ventricular Systolic Dysfunction From Electrocardiographic Images
- 2023
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Ingår i: Circulation. - : Wolters Kluwer. - 0009-7322 .- 1524-4539. ; 148:9, s. 765-777
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Left ventricular (LV) systolic dysfunction is associated with a >8-fold increased risk of heart failure and a 2-fold risk of premature death. The use of ECG signals in screening for LV systolic dysfunction is limited by their availability to clinicians. We developed a novel deep learning-based approach that can use ECG images for the screening of LV systolic dysfunction.METHODS: Using 12-lead ECGs plotted in multiple different formats, and corresponding echocardiographic data recorded within 15 days from the Yale New Haven Hospital between 2015 and 2021, we developed a convolutional neural network algorithm to detect an LV ejection fraction <40%. The model was validated within clinical settings at Yale New Haven Hospital and externally on ECG images from Cedars Sinai Medical Center in Los Angeles, CA; Lake Regional Hospital in Osage Beach, MO; Memorial Hermann Southeast Hospital in Houston, TX; and Methodist Cardiology Clinic of San Antonio, TX. In addition, it was validated in the prospective Brazilian Longitudinal Study of Adult Health. Gradient-weighted class activation mapping was used to localize class-discriminating signals on ECG images.RESULTS: Overall, 385 601 ECGs with paired echocardiograms were used for model development. The model demonstrated high discrimination across various ECG image formats and calibrations in internal validation (area under receiving operation characteristics [AUROCs], 0.91; area under precision-recall curve [AUPRC], 0.55); and external sets of ECG images from Cedars Sinai (AUROC, 0.90 and AUPRC, 0.53), outpatient Yale New Haven Hospital clinics (AUROC, 0.94 and AUPRC, 0.77), Lake Regional Hospital (AUROC, 0.90 and AUPRC, 0.88), Memorial Hermann Southeast Hospital (AUROC, 0.91 and AUPRC 0.88), Methodist Cardiology Clinic (AUROC, 0.90 and AUPRC, 0.74), and Brazilian Longitudinal Study of Adult Health cohort (AUROC, 0.95 and AUPRC, 0.45). An ECG suggestive of LV systolic dysfunction portended >27-fold higher odds of LV systolic dysfunction on transthoracic echocardiogram (odds ratio, 27.5 [95% CI, 22.3-33.9] in the held-out set). Class-discriminative patterns localized to the anterior and anteroseptal leads (V2 and V3), corresponding to the left ventricle regardless of the ECG layout. A positive ECG screen in individuals with an LV ejection fraction & GE;40% at the time of initial assessment was associated with a 3.9-fold increased risk of developing incident LV systolic dysfunction in the future (hazard ratio, 3.9 [95% CI, 3.3-4.7]; median follow-up, 3.2 years).CONCLUSIONS: We developed and externally validated a deep learning model that identifies LV systolic dysfunction from ECG images. This approach represents an automated and accessible screening strategy for LV systolic dysfunction, particularly in low-resource settings.
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| 29. |
- Shoja, Siamak, 1980, et al.
(författare)
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Microstructure investigation of textured CVD alumina coatings
- 2020
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Ingår i: International Journal of Refractory Metals and Hard Materials. - : Elsevier BV. - 0263-4368 .- 2213-3917. ; 87
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Tidskriftsartikel (refereegranskat)abstract
- This study concerns the interfacial microstructure and texture development in three textured CVD alpha-Al2O3 coatings using X-ray diffraction, transmission Kikuchi diffraction, scanning transmission electron microscopy and energy dispersive X-ray analysis. It is well known that the performance of these types of coatings relies on the degree and type of texture. The aim of this work is to study the microstructure of three different CVD alpha-Al2O3 layers when deposited onto a Ti(C,N,O) bonding layer. The coatings were deposited onto cemented carbide/cobalt substrates (WC/Co). It was observed that grain boundary diffusion of W and Co occurred through the TiN and Ti(C,N) layers to the bonding layer/alpha-Al2O3 interface. This may disturb the alumina layer nucleation and early growth. Interfacial porosity was observed at the bonding layer/alpha-Al2O3 interface. The number of voids that were detected in the (0001) and (01 (1) over bar0)-textured coatings was similar when H2S was not used during the initial deposition step. When H2S was present during the nucleation step deposition of the alpha-Al2O3 more voids were introduced at the interface for the (0001)-textured samples. The alumina grain morphology developed from small (similar to 100 nm) equiaxed grains at the start of the alumina coating to larger (several microns) columnar grains at the top of the coating. The inner part of the alumina coatings had a more random orientation. The texture changed either: (i) gradually over several grains, or (ii) more abruptly from one grain to another; from more random orientations to the desired texture. The desired texture develops earlier when using H2S at the start for the (0001)-textured coatings, while the (01 (1) over bar0)-texture development benefits from the absence of H2S. Thus, in this study, H2S promotes (0001) texture and interfacial void formation.
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| 30. |
- Sihver, Lembit, 1962, et al.
(författare)
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Biological protection in deep space missions
- 2021
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Ingår i: Journal of Biomedical Physics and Engineering. - : Salvia Medical Sciences Ltd. - 2251-7200. ; 11:6, s. 663-674
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Forskningsöversikt (refereegranskat)abstract
- During deep space missions, astronauts are exposed to highly ionizing radiation, incl. neutrons, protons and heavy ions from galactic cosmic rays (GCR), solar wind (SW) and solar energetic particles (SEP). This increase the risks for cancerogenisis, damages in central nervous system (CNS), cardiovascular diseases, etc. Large SEP events can even cause acute radiation syndrome (ARS). Long term manned deep space missions will therefor require unique radiation protection strategies. Since it has been shown that physical shielding alone is not sufficient, this paper propose pre-flight screening of the aspirants for evaluation of their level of adaptive responses. Methods for boosting their immune system, should also be further investigated, and the possibility of using radiation effect modulators are discussed. In this paper, especially, the use of vitamin C as a promising non-toxic, cost-effective, easily available radiation mitigator (which can be used hours after irradiation), is described. Although it has previously been shown that vitamin C can decrease radiation-induced chromosomal damage in rodents, it must be further investigated before any conclusions about its radiation mitigating properties in humans can be concluded.
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| 31. |
- Sihver, Lembit, 1962, et al.
(författare)
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Space Dosimetry and Space Phantom Experiments
- 2021
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Ingår i: IEEE Aerospace Conference Proceedings. - 1095-323X. ; 2021-March
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Konferensbidrag (refereegranskat)abstract
- To estimate the space radiation risks for the future planned Mars missions, the radiation fields in the spacecraft and in the habitats on Mars must be fully known. For radiation risk estimations, benchmarking and improving particle and ion transport codes which are currently used for space radiation and shielding calculations, radiation detection and monitoring of the space radiation field as a function of the solar activity, the orbital parameters and the different shielding configurations of the International Space Station (ISS) have been performed and are still ongoing. There are also many ongoing measurements of the spatial and temporal distribution of the radiation field at the ISS. In addition to the measurements at the ISS, important information about radiation environment in deep space was achieved with the Mars Science Laboratory (MSL) spacecraft, containing the Curiosity rover, which was launched to Mars on 26 November 2011, and traveled for 253 days, 560 million kilometers to Mars. The Radiation Assessment Detector (RAD) on the spacecraft showed that the dose equivalent for even the shortest round-trip Earth-Mars journeys, with current propulsion systems and current available shielding, is 0.7 +/- 0.1 Sv, depending on the solar cycle and duration of the mission. Although the dose rate on the surface of Mars is lower than in deep space, measurements with RAD showed that an astronaut would still get around 40% of the dose rate in deep space. If the astronauts are exposed to large Solar Particle Events (SPEs), the dose can reach lethal doses. Effective countermeasures should therefore be developed before performing a manned mission to Mars. The use of human phantoms in space that simulate an astronaut's body, has provided detailed information of the depth-dose distributions, and radiation quality, inside the human body in space. This information is essential for developing more accurate space radiation transport and risk models to be used for evaluating short and long-term radiation risks in deep space and on Mars. Although reports state that background radiation in some high background radiation areas approaches that of the Martian surface, new estimates show that the maximum annual radiation dose in these areas can be much higher than that of the Martian surface. Given this consideration, study of the health effects of exposure to high levels of natural radiation can help scientist better evaluate the risk of radiation in deep space manned missions. This paper presents a short review of some important published space dosimetry and phantom experiments, and discusses some recently proposed counter measures to reduce the health risks of the astronauts on deep space missions.
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