14 results on '"Arz M"'
Search Results
2. Effects of daily artificial gravity training on orthostatic tolerance following 60-day strict head-down tilt bedrest
- Author
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Hoenemann, J.-N., Moestl, S., van Herwaarden, A. E., Diedrich, A., Mulder, E., Frett, T., Petrat, G., Pustowalow, W., Arz, M., Heusser, K., Lee, S., Jordan, J., Tank, J., and Hoffmann, F.
- Published
- 2023
- Full Text
- View/download PDF
3. Impact of daily artificial gravity on autonomic cardiovascular control following 60-day head-down tilt bed rest
- Author
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Hoenemann, J.-N., primary, Moestl, S., additional, Diedrich, A., additional, Mulder, E., additional, Frett, T., additional, Petrat, G., additional, Pustowalow, W., additional, Arz, M., additional, Schmitz, M.-T., additional, Heusser, K., additional, Lee, S. M. C., additional, Jordan, J., additional, Tank, J., additional, and Hoffmann, F., additional
- Published
- 2023
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4. Effects of daily artificial gravity training on orthostatic tolerance following 60-day strict head-down tilt bedrest.
- Author
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Hoenemann, J.N., Moestl, S., Herwaarden, A.E. van, Diedrich, A., Mulder, E., Frett, T., Petrat, G., Pustowalow, W., Arz, M., Heusser, K., Lee, S., Jordan, J., Tank, J., Hoffmann, F., Hoenemann, J.N., Moestl, S., Herwaarden, A.E. van, Diedrich, A., Mulder, E., Frett, T., Petrat, G., Pustowalow, W., Arz, M., Heusser, K., Lee, S., Jordan, J., Tank, J., and Hoffmann, F.
- Abstract
01 augustus 2023, Contains fulltext : 295998.pdf (Publisher’s version ) (Open Access), PURPOSE: Orthostatic intolerance commonly occurs following immobilization or space flight. We hypothesized that daily artificial gravity training through short-arm centrifugation could help to maintain orthostatic tolerance following head-down tilt bedrest, which is an established terrestrial model for weightlessness. METHODS: We studied 24 healthy persons (eight women; age 33.3 ± 9.0 years; BMI 24.3 ± 2.1 kg/m(2)) who participated in the 60-days head-down tilt bedrest (AGBRESA) study. They were assigned to 30 min/day continuous or 6 × 5 min intermittent short-arm centrifugation with 1Gz at the center of mass or a control group. We performed head-up tilt testing with incremental lower-body negative pressure until presyncope before and after bedrest. We recorded an electrocardiogram, beat-to-beat finger blood pressure, and brachial blood pressure and obtained blood samples from an antecubital venous catheter. Orthostatic tolerance was defined as time to presyncope. We related changes in orthostatic tolerance to changes in plasma volume determined by carbon dioxide rebreathing. RESULTS: Compared with baseline measurements, supine and upright heart rate increased in all three groups following head-down tilt bedrest. Compared with baseline measurements, time to presyncope decreased by 323 ± 235 s with continuous centrifugation, by 296 ± 508 s with intermittent centrifugation, and by 801 ± 354 s in the control group (p = 0.0249 between interventions). The change in orthostatic tolerance was not correlated with changes in plasma volume. CONCLUSIONS: Daily artificial gravity training on a short-arm centrifuge attenuated the reduction in orthostatic tolerance after 60 days of head-down tilt bedrest.
- Published
- 2023
5. Mode of Signal Transduction in the Wheat/Rust-System
- Author
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Arz, M. C., Gotthardt, U., Grambow, H. J., Fritig, Bernard, editor, and Legrand, Michel, editor
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- 1993
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6. Visual Dwell Time on instruments is associated with Manual Docking Performance
- Author
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Piechowski, S., Pustowalow, W., Arz, M., Rittweger, J., Mühl, C., Mulder, E., and Wolf, O.T.
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Bedrest ,Cognition ,Attention ,Space ,Eye-Tracking ,Docking - Published
- 2021
7. Individual Learning Curves in Manual Control of Six Degrees of Freedom
- Author
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Johannes, B.W., Bronnikov, S.V., Bubeev, Y., Arz, M., Piechowski, S., and Rittweger, J.
- Subjects
Perceptual-motor Performance ,Intelligent self-sufficient Tutor ,Simulation-based skill acquisition ,Muskel- und Knochenstoffwechsel - Abstract
A newly developed tool to facilitate learning processes in complex perceptual-motor tasks was tested for its efficiency characteristics. The tool is based on a demanding manual control task, in which a target object has to be manipulated with six degrees of freedom. During the self-sufficient learning process the task difficulty is increased from very easy to the complex level of a manual spacecraft docking on a space station. The type and the difficulty of the next task were defined by a regulation system based on individual performance. The tool was successfully applied to 22 participants in a laboratory setting. No performance differences were found between genders. Age was correlated with training duration but slower learners also succeeded eventually. The tool provides improvements in the learning process for operational tasks like controlling a robot arm or to perform a docking maneuver. Beside the foreseen practical application in space this is a time effective and economic way to educate participants in ground based research requiring such complex skills.
- Published
- 2019
8. Artificial nesting success and nest building behavior of common myna, Acridotheres tristis using paper/plastic
- Author
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Arz Muhammad Umrani, Ahmad Zamir, Talha Anwar, Umair Safdar, Aimal Khan Barki, Mamoona Wali Muhammad, Sajjad Saeed, Sohaib Ahmed, Muhammad Sajawal, Jawaid Ahmed, Samina Malik, Aijazan Parveen, Muhammad Adnan, Muhammad Omer Dalair, and Danyal Khan
- Subjects
artificial nests ,common myna ,reproductive success ,breeding season ,Environmental sciences ,GE1-350 ,Science - Abstract
The objective of this paper is to analyze the nesting success and nest building behavior of myna, Acridotheres tristis, using paper/plastic Myna in artificial nest. The boxes were placed at different sites, including University Town, Rahat Abad and Qadir Abad in Peshawar City, Pakistan. The artificial nests were designed 56 × 22 cm and 21 × 16 cm in dimension with respective opening of 8 cm and 7 cm. Total number of artificial nests were 55, therein, number of successful next recorded 42 and unsuccessful 13. Artificial nests were installed in breeding season of common myna. Total nesting success was 85.71 in March-April; 68.18 in May-June and 78.94 in July-August 2022. Nest losses were recorded during six months (March to August). Total success rate (%) was 76.36% and the mean (± SD) number of plastic collected as nesting material per day was 18.8 ± 3.12.
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- 2022
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9. Anaplastic T cell lymphoma in a patient with autoimmune hepatitis and hepatitis C infection
- Author
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Hina Ismail, Nishat Akbar, Ghazi Abrar, Arz Mohammad, Syed Zahid Shah, Zain Majid, and Nasir Hassan Luck
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anaplastic t cell lymphoma ,hcv infection ,non-hodgkin lymphoma ,Specialties of internal medicine ,RC581-951 ,Infectious and parasitic diseases ,RC109-216 - Abstract
Lymphomas are rarely associated with liver disease. We hereby present a case of anaplastic T cell lymphoma in a 45-year-old female, who had received four cycles CHOP chemotherapy regimen and was evaluated for abdominal pain, fever along with weight loss. She was later found to have features of chronic liver disease on ultrasound along with varices on screening endoscopy. Serological workup was positive for hepatitis C infection while her liver biopsy showed features of autoimmune hepatitis. She was managed with steroids and azathioprine along with direct acting antiviral agents.
- Published
- 2021
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10. Acute cardiovascular and muscular response to rowing ergometer exercise in artificial gravity - a pilot trial.
- Author
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Frett T, Lecheler L, Arz M, Pustowalow W, Petrat G, Mommsen F, Breuer J, Schmitz MT, Green DA, and Jordan J
- Abstract
Prolonged immobilization and spaceflight cause cardiovascular and musculoskeletal deconditioning. Combining artificial gravity through short-arm centrifugation with rowing exercise may serve as a countermeasure. We aimed to compare the tolerability, muscle force production, cardiovascular response, and power output of rowing on a short-arm centrifuge and under terrestrial gravity. Twelve rowing athletes (4 women, aged 27.2 ± 7.4 years, height 179 ± 0.1 cm, mass 73.7 ± 9.4 kg) participated in two rowing sessions, spaced at least six weeks apart. One session used a short-arm centrifuge with +0.5 Gz, while the other inclined the rowing ergometer by 26.6° to mimic centrifugal loading. Participants started self-paced rowing at 30 W, increasing by 15 W every three minutes until exhaustion. We measured rowing performance, heart rate, blood pressure, ground reaction forces, leg muscle activation, and blood lactate concentration. Rowing on the centrifuge was well-tolerated without adverse events. No significant differences in heart rate, blood pressure, or blood lactate concentration were observed between conditions. Inclined rowing under artificial gravity resulted in lower power output (-33%, p < 0.001) compared to natural gravity, but produced higher mean and peak ground reaction forces (p < 0.0001) and increased leg muscle activation. Muscle activation and ground reaction forces varied with rotational direction. Rowing in artificial gravity shows promise as a strategy against cardiovascular and muscular deconditioning during long-term spaceflight, but further investigation is required to understand its long-term effects., (© 2024. The Author(s).)
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- 2024
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11. Visual Attention Relates to Operator Performance in Spacecraft Docking Training.
- Author
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Piechowski S, Johannes B, Pustowalow W, Arz M, Mulder E, Jordan J, Wolf OT, and Rittweger J
- Subjects
- Cognition, Computer Simulation, Female, Humans, Male, Eye Movements, Spacecraft
- Abstract
BACKGROUND: Manually controlled docking of a spacecraft to a space station is an operational task that poses high demands on cognitive and perceptual functioning. Effective processing of visual information is crucial for success. Eye tracking can reveal the operator's attentional focus unobtrusively and objectively. Therefore, our aim was to test the feasibility of eye tracking during a simulation of manual docking and to identify links between visual information processing and performance. METHODS: We hypothesized that duration and number of gazes to specific regions of interest of the simulation (total dwell time and number of dwells) would be associated with docking accuracy. Eye movements were recorded in 10 subjects (30% women, M = 33.4 yr old) during the 6° head-down tilt bed rest study AGBRESA during 20 training sessions with the 6df learning program for spacecraft docking. RESULTS: Subjects' gaze was directed most frequently and longest to the vizor (185 dwells and 22,355 ms per task) followed by the two instrument displays (together 75 dwells and 4048 ms per task). We observed a significant positive relationship between number and duration of visual checks of speed and distance to the docking point and the accuracy of the docking maneuver. DISCUSSION: In conclusion, eye tracking provides valuable information related to docking accuracy that might prospectively offer the opportunity to improve docking training effectiveness. Piechowski S, Johannes B, Pustowalow W, Arz M, Mulder E, Jordan J, Wolf OT, Rittweger J. Visual attention relates to operator performance in spacecraft docking training . Aerosp Med Hum Perform. 2022; 93(6):480-486.
- Published
- 2022
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12. Quantitative Evaluation of a Telerobotic System for Vascular Ultrasound Measurement on a Short Arm Human Centrifuge.
- Author
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Frett T, Petrat G, Arz M, and Leguy C
- Abstract
Artificial Gravity generated by Short Arm Human Centrifuges is a promising multi-system countermeasure for physiological deconditioning during long duration space flights. To allow a continuous assessment of cardiovascular hemodynamics during centrifugation, a telerobotic robotic system holding an ultrasound probe has been installed on a Short Arm Human Centrifuge. A feasibility study was conducted to define the use capabilities and limitations of such a novel method. The objective of this study is to estimate the reproducibility and precision of remotely controlled vascular ultrasound assessment under centrifugation by assessing peripheral vascular diameter and wall distension. Four repeated centrifugation runs of 5 min, with 2.4 g at feet level, were performed including a 15 min rest between each run for a group of eight healthy male volunteers. Vascular diameter and distention were assessed for the common carotid artery (CCA) and the femoral artery (FA) by ultrasound imaging using a 10 MHz linear array probe (Mylab1, Esaote). Ultrasound measurements were consecutively performed: a) by an expert user in hand-held mode in standing as well as supine position, b) using the telerobotic arm without centrifugation as baseline and c) using the telerobotic arm during centrifugation. Vascular responses were compared between baseline and under centrifugation. Inter-, intra-registration and group variability have been assessed for hand-held and remotely controlled examination. The results show that intra-registration variability, σ
h , was always smaller than inter-registration variability, σm , that is in turned smaller than the inter-subject variability σg ( σh < σm < σg ). Centrifugation caused no significant changes in CCA diameter but a lower carotid distension compared to manual and robotic ultrasound in supine position ( p < 0.05). Femoral diameter was significantly decreased in hypergravity compared to robotic sonography without centrifugation. A good reproducibility and precision of the remotely controlled vascular ultrasound assessment under centrifugation could be demonstrated. In conclusion, arterial wall dynamics can be precisely assessed for the CCA and femoral artery during centrifugation using a telerobotic ultrasound measurement system. Potential improvements to further enhance reproducibility and safety of the system are discussed., Competing Interests: Conflict of InterestAuthors report no conflict of interest., (© The Author(s) 2021.)- Published
- 2021
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13. Tolerability of daily intermittent or continuous short-arm centrifugation during 60-day 6o head down bed rest (AGBRESA study).
- Author
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Frett T, Green DA, Mulder E, Noppe A, Arz M, Pustowalow W, Petrat G, Tegtbur U, and Jordan J
- Subjects
- Bed Rest, Blood Pressure, Cohort Studies, Female, Head-Down Tilt, Healthy Volunteers, Heart Rate, Humans, Male, Centrifugation, Gravity, Altered adverse effects, Motion Sickness
- Abstract
Artificial gravity through short-arm centrifugation has potential as a multi-system countermeasure for deconditioning and cranial fluid shifts that may underlie ocular issues in microgravity. However, the optimal short-arm centrifugation protocol that is effective whilst remaining tolerable has yet to be determined. Given that exposure to centrifugation is associated with presyncope and syncope and in addition motion sickness an intermittent protocol has been suggested to be more tolerable. Therefore, we assessed cardiovascular loading and subjective tolerability of daily short arm centrifugation with either an intermittent or a continuous protocol during long-term head-down bed rest as model for microgravity exposure in a mixed sex cohort. During the Artificial Gravity Bed Rest with European Space Agency (AGBRESA) 60 day 6° head down tilt bed rest study we compared the tolerability of daily +1 Gz exposure at the center of mass centrifugation, either performed continuously for 30 minutes, or intermittedly (6 x 5 minutes). Heart rate and blood pressure were assessed daily during centrifugation along with post motion sickness scoring and rate of perceived exertion. During bed rest, 16 subjects (6 women, 10 men), underwent 960 centrifuge runs in total. Ten centrifuge runs had to be terminated prematurely, 8 continuous runs and 2 intermittent runs, mostly due to pre-syncopal symptoms and not motion sickness. All subjects were, however, able to resume centrifuge training on subsequent days. We conclude that both continuous and intermittent short-arm centrifugation protocols providing artificial gravity equivalent to +1 Gz at the center of mass is tolerable in terms of cardiovascular loading and motion sickness during long-term head down tilt bed rest. However, intermittent centrifugation appears marginally better tolerated, albeit differences appear minor., Competing Interests: The authors declare no competing interests as KBRwyle GmbH had no role in the study design and thus this does not alter our adherence to PLOS ONE policies on sharing data and materials.
- Published
- 2020
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14. Motion sickness symptoms during jumping exercise on a short-arm centrifuge.
- Author
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Frett T, Green DA, Arz M, Noppe A, Petrat G, Kramer A, Kuemmel J, Tegtbur U, and Jordan J
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- Adaptation, Physiological, Adult, Aerospace Medicine, Centrifugation instrumentation, Exercise physiology, Gravitation, Head Movements physiology, Healthy Volunteers, Humans, Male, Motion Sickness physiopathology, Motion Sickness prevention & control, Weightlessness Countermeasures, Young Adult, Centrifugation adverse effects, Gravity, Altered adverse effects, Motion Sickness etiology, Space Flight
- Abstract
Artificial gravity elicited through short-arm human centrifugation combined with physical exercise, such as jumping, is promising in maintaining health and performance during space travel. However, motion sickness symptoms could limit the tolerability of the approach. Therefore, we determined the feasibility and tolerability, particularly occurrence of motion sickness symptoms, during reactive jumping exercises on a short-arm centrifuge. In 15 healthy men, we assessed motion sickness induced by jumping exercises during short-arm centrifugation at constant +1Gz or randomized variable +0.5, +0.75, +1, +1.25 and +1.5 Gz along the body axis referenced to center of mass. Jumping in the upright position served as control intervention. Test sessions were conducted on separate days in a randomized and cross-over fashion. All participants tolerated jumping exercises against terrestrial gravity and on the short-arm centrifuge during 1 Gz or variable Gz at the center of mass without disabling motion sickness symptoms. While head movements markedly differed, motion sickness scores were only modestly increased with jumping on the short-arm centrifuge compared with vertical jumps. Our study demonstrates that repetitive jumping exercises are feasible and tolerable during short-arm centrifugation. Since jumping exercises maintain muscle and bone mass, our study enables further development of exercise countermeasures in artificial gravity., Competing Interests: KBRwyle GmbH provided the salary for D.G but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The authors declare no competing interests as KBRwyle GmbH had no role in the study design and thus this does not alter our adherence to PLOS ONE policies on sharing data and materials.
- Published
- 2020
- Full Text
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