The Experts below are selected from a list of 30588 Experts worldwide ranked by ideXlab platform
Herbert Biebach - One of the best experts on this subject based on the ideXlab platform.
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Flight Altitude of trans sahara migrants in autumn a comparison of radar observations with predictions from meteorological conditions and water and energy balance models
Journal of Avian Biology, 2000Co-Authors: Marcel Klaassen, Herbert BiebachAbstract:Radar observations on the Altitude of bird migration and altitudinal profiles of meteorological conditions over the Sahara desert are presented for the autumn migratory period. Migratory birds fly at an average Altitude of 1016 m (a.s.l.) during the day and 571 m during the night. Weather data served to calculate Flight range using two models: an energy model (EM) and an energy-and-water model (EWM). The EM assumes that fuel supply limits Flight range whereas the EWM assumes that both fuel and water may limit Flight range. Flight ranges estimated with the EM were generally longer than those with the EWM. This indicates that trans-Sahara migrants might have more problems balancing their water than their energy budget. However, if we assume fuel stores to consist of 70% instead of 100% fat (the remainder consisting of 9% protein and 21% water), predicted Flight ranges of the EM and EWM largely overlap. Increased oxygen extraction, reduced Flight costs, reduced exhaled air temperature, reduced cutaneous water loss and increased tolerance to water loss are potential physiological adaptations that would improve the water budget in migrants. Both the EM and EWM predict optimal Flight Altitudes in agreement with radar observations in autumn. Optimal Flight Altitudes are differently predicted by the EM and EWM for nocturnal spring migration. During spring, the EWM predicts moderately higher and the EM substantially higher Flight Altitudes than during autumn. EWM predictions are therefore in better agreement with radar observations on Flight Altitude of migrants over the Negev desert in spring than EM predictions.
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Flight Altitude of trans‐Sahara migrants in autumn: a comparison of radar observations with predictions from meteorological conditions and water and energy balance models
Journal of Avian Biology, 2000Co-Authors: Marcel Klaassen, Herbert BiebachAbstract:Radar observations on the Altitude of bird migration and altitudinal profiles of meteorological conditions over the Sahara desert are presented for the autumn migratory period. Migratory birds fly at an average Altitude of 1016 m (a.s.l.) during the day and 571 m during the night. Weather data served to calculate Flight range using two models: an energy model (EM) and an energy-and-water model (EWM). The EM assumes that fuel supply limits Flight range whereas the EWM assumes that both fuel and water may limit Flight range. Flight ranges estimated with the EM were generally longer than those with the EWM. This indicates that trans-Sahara migrants might have more problems balancing their water than their energy budget. However, if we assume fuel stores to consist of 70% instead of 100% fat (the remainder consisting of 9% protein and 21% water), predicted Flight ranges of the EM and EWM largely overlap. Increased oxygen extraction, reduced Flight costs, reduced exhaled air temperature, reduced cutaneous water loss and increased tolerance to water loss are potential physiological adaptations that would improve the water budget in migrants. Both the EM and EWM predict optimal Flight Altitudes in agreement with radar observations in autumn. Optimal Flight Altitudes are differently predicted by the EM and EWM for nocturnal spring migration. During spring, the EWM predicts moderately higher and the EM substantially higher Flight Altitudes than during autumn. EWM predictions are therefore in better agreement with radar observations on Flight Altitude of migrants over the Negev desert in spring than EM predictions.
Simona Clichici - One of the best experts on this subject based on the ideXlab platform.
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Antioxidant protection against cosmic radiation-induced oxidative stress at commercial Flight Altitude
Journal of Physiology and Pharmacology, 2018Co-Authors: D. R. Mitrea, H. Mortazavi Moshkenani, O. A. Hoteiuc, C. Bidian, Alina Mihaela Toader, Simona ClichiciAbstract:It is proposed that at the commercial Flight Altitude the cosmic radiation affects the human body and induces the oxidative stress. This review presents data to support this idea and also cumulates the information to provide the basis for antioxidant supplementation in persons that travel by plane at high Altitudes. The conclusion is that the heterogeneity of cosmic radiation can produce different effects on human body through different mechanisms and the prophylactic treatment with antioxidants can reduce the oxidative stress generated by the radiation exposure.
Francisca Lopezgranados - One of the best experts on this subject based on the ideXlab platform.
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quantifying efficacy and limits of unmanned aerial vehicle uav technology for weed seedling detection as affected by sensor resolution
Sensors, 2015Co-Authors: Jose M Pena, Jorge Torressanchez, Angelica Serranoperez, Ana Isabel De Castro, Francisca LopezgranadosAbstract:In order to optimize the application of herbicides in weed-crop systems, accurate and timely weed maps of the crop-field are required. In this context, this investigation quantified the efficacy and limitations of remote images collected with an unmanned aerial vehicle (UAV) for early detection of weed seedlings. The ability to discriminate weeds was significantly affected by the imagery spectral (type of camera), spatial (Flight Altitude) and temporal (the date of the study) resolutions. The colour-infrared images captured at 40 m and 50 days after sowing (date 2), when plants had 5–6 true leaves, had the highest weed detection accuracy (up to 91%). At this Flight Altitude, the images captured before date 2 had slightly better results than the images captured later. However, this trend changed in the visible-light images captured at 60 m and higher, which had notably better results on date 3 (57 days after sowing) because of the larger size of the weed plants. Our results showed the requirements on spectral and spatial resolutions needed to generate a suitable weed map early in the growing season, as well as the best moment for the UAV image acquisition, with the ultimate objective of applying site-specific weed management operations.
Marcel Klaassen - One of the best experts on this subject based on the ideXlab platform.
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Flight Altitude of trans sahara migrants in autumn a comparison of radar observations with predictions from meteorological conditions and water and energy balance models
Journal of Avian Biology, 2000Co-Authors: Marcel Klaassen, Herbert BiebachAbstract:Radar observations on the Altitude of bird migration and altitudinal profiles of meteorological conditions over the Sahara desert are presented for the autumn migratory period. Migratory birds fly at an average Altitude of 1016 m (a.s.l.) during the day and 571 m during the night. Weather data served to calculate Flight range using two models: an energy model (EM) and an energy-and-water model (EWM). The EM assumes that fuel supply limits Flight range whereas the EWM assumes that both fuel and water may limit Flight range. Flight ranges estimated with the EM were generally longer than those with the EWM. This indicates that trans-Sahara migrants might have more problems balancing their water than their energy budget. However, if we assume fuel stores to consist of 70% instead of 100% fat (the remainder consisting of 9% protein and 21% water), predicted Flight ranges of the EM and EWM largely overlap. Increased oxygen extraction, reduced Flight costs, reduced exhaled air temperature, reduced cutaneous water loss and increased tolerance to water loss are potential physiological adaptations that would improve the water budget in migrants. Both the EM and EWM predict optimal Flight Altitudes in agreement with radar observations in autumn. Optimal Flight Altitudes are differently predicted by the EM and EWM for nocturnal spring migration. During spring, the EWM predicts moderately higher and the EM substantially higher Flight Altitudes than during autumn. EWM predictions are therefore in better agreement with radar observations on Flight Altitude of migrants over the Negev desert in spring than EM predictions.
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Flight Altitude of trans‐Sahara migrants in autumn: a comparison of radar observations with predictions from meteorological conditions and water and energy balance models
Journal of Avian Biology, 2000Co-Authors: Marcel Klaassen, Herbert BiebachAbstract:Radar observations on the Altitude of bird migration and altitudinal profiles of meteorological conditions over the Sahara desert are presented for the autumn migratory period. Migratory birds fly at an average Altitude of 1016 m (a.s.l.) during the day and 571 m during the night. Weather data served to calculate Flight range using two models: an energy model (EM) and an energy-and-water model (EWM). The EM assumes that fuel supply limits Flight range whereas the EWM assumes that both fuel and water may limit Flight range. Flight ranges estimated with the EM were generally longer than those with the EWM. This indicates that trans-Sahara migrants might have more problems balancing their water than their energy budget. However, if we assume fuel stores to consist of 70% instead of 100% fat (the remainder consisting of 9% protein and 21% water), predicted Flight ranges of the EM and EWM largely overlap. Increased oxygen extraction, reduced Flight costs, reduced exhaled air temperature, reduced cutaneous water loss and increased tolerance to water loss are potential physiological adaptations that would improve the water budget in migrants. Both the EM and EWM predict optimal Flight Altitudes in agreement with radar observations in autumn. Optimal Flight Altitudes are differently predicted by the EM and EWM for nocturnal spring migration. During spring, the EWM predicts moderately higher and the EM substantially higher Flight Altitudes than during autumn. EWM predictions are therefore in better agreement with radar observations on Flight Altitude of migrants over the Negev desert in spring than EM predictions.
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Predicting migratory Flight Altitudes by physiological migration models
The Auk, 2000Co-Authors: Felix Liechti, Marcel Klaassen, Bruno BrudererAbstract:Using the altitudinal profiles of wind, temperature, pressure, and humidity in three Flight models, we tried to explain the altitudinal distributions of nocturnal migrants recorded by radar above a desert in southern Israel. In the simplest model, only the tailwind component was used as a predictor of the most preferred Flight Altitude (T model). The energy model (E model) predicted Flight ranges according to mechanical power consumption in flapping Flight depending on air density and wind conditions, assuming optimal adjustment of airspeed and compensation of crosswinds, and including the influence of mass loss during Flight. The energy-water model (EW model) used the same assumptions and parameters as the E model but also included restrictions caused by dehydration. Because wind was by far the most important factor governing altitudinal distribution of nocturnal migrants, differences in predictions of the three models were small. In a first approach, the EW model performed slightly better than the E model, and both performed slightly better than the T model. Differences were most pronounced in spring, when migrants should fly high according to wind conditions, but when climbing and descending they must cross lower Altitudes where conditions are better with respect to dehydration. A simplified energy model (Es model) that omits the effect of air density on Flight costs explained the same amount of variance in Flight Altitude as the more complicated E and EW models. By omitting the effect of air density, the Es model predicted lower Flight Altitudes and thus compensated for factors that generally bias height distributions downward but are not considered in the models (i.e. climb and descent through lower air layers, cost of ascent, and decrease of oxygen partial pressure with Altitude). Our results confirm that wind profiles, and thus energy rather than water limitations, govern the altitudinal distribution of nocturnal migrants, even under the extreme humidity and temperature conditions in the trade wind zone.
Gilles Montagne - One of the best experts on this subject based on the ideXlab platform.
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Eye position affects Flight Altitude in visual approach to landing independent of level of expertise of pilot.
PLOS ONE, 2018Co-Authors: David M. Jacobs, Antoine H. P. Morice, Cyril Camachon, Gilles MontagneAbstract:The present study addresses the effect of the eye position in the cockpit on the Flight Altitude during the final approach to landing. Three groups of participants with different levels of expertise (novices, trainees, and certified pilots) were given a laptop with a Flight simulator and they were asked to maintain a 3.71° glide slope while landing. Each participant performed 40 approaches to the runway. During 8 of the approaches, the point of view that the Flight simulator used to compute the visual scene was slowly raised or lowered with 4 cm with respect to the cockpit, hence moving the projection of the visible part of the cockpit down or up in the visible scene in a hardly noticeable manner. The increases and decreases in the simulated eye height led to increases and decreases in the Altitude of the approach trajectories, for all three groups of participants. On the basis of these results, it is argued that the eye position of pilots during visual approaches is a factor that contributes to the risk of black hole accidents.
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Eye position affects Flight Altitude in visual approach to landing independent of level of expertise of pilot
PLoS ONE, 2018Co-Authors: David Jacobs, Antoine H. P. Morice, Cyril Camachon, Gilles MontagneAbstract:The present study addresses the effect of the eye position in the cockpit on the Flight Altitude during the final approach to landing. Three groups of participants with different levels of expertise (novices, trainees, and certified pilots) were given a laptop with a Flight simulator and they were asked to maintain a 3.71˚glide71˚glide slope while landing. Each participant performed 40 approaches to the runway. During 8 of the approaches, the point of view that the Flight simulator used to compute the visual scene was slowly raised or lowered with 4 cm with respect to the cockpit, hence moving the projection of the visible part of the cockpit down or up in the visible scene in a hardly noticeable manner. The increases and decreases in the simulated eye height led to increases and decreases in the Altitude of the approach trajectories, for all three groups of participants. On the basis of these results, it is argued that the eye position of pilots during visual approaches is a factor that contributes to the risk of black hole accidents.
