SciCombinator

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Concept: Altitude

163

Track-while-scan bird radars are widely used in ornithological studies, but often the precise detection capabilities of these systems are unknown. Quantification of radar performance is essential to avoid observational biases, which requires practical methods for validating a radar’s detection capability in specific field settings. In this study a method to quantify the detection capability of a bird radar is presented, as well a demonstration of this method in a case study. By time-referencing line-transect surveys, visually identified birds were automatically linked to individual tracks using their transect crossing time. Detection probabilities were determined as the fraction of the total set of visual observations that could be linked to radar tracks. To avoid ambiguities in assigning radar tracks to visual observations, the observer’s accuracy in determining a bird’s transect crossing time was taken into account. The accuracy was determined by examining the effect of a time lag applied to the visual observations on the number of matches found with radar tracks. Effects of flight altitude, distance, surface substrate and species size on the detection probability by the radar were quantified in a marine intertidal study area. Detection probability varied strongly with all these factors, as well as species-specific flight behaviour. The effective detection range for single birds flying at low altitude for an X-band marine radar based system was estimated at ∼1.5 km. Within this range the fraction of individual flying birds that were detected by the radar was 0.50±0.06 with a detection bias towards higher flight altitudes, larger birds and high tide situations. Besides radar validation, which we consider essential when quantification of bird numbers is important, our method of linking radar tracks to ground-truthed field observations can facilitate species-specific studies using surveillance radars. The methodology may prove equally useful for optimising tracking algorithms.

Concepts: Radar tracker, Marine radar, Air traffic control, Bias, Altitude, Flight level, Radar, Scientific method

30

Acute mountain sickness (AMS) and large decrements in endurance exercise performance occur when unacclimatized individuals rapidly ascend to high altitudes. Six altitude and hypoxia preacclimatization strategies were evaluated to determine their effectiveness for minimizing AMS and improving performance during altitude exposures. Strategies using hypobaric chambers or true altitude were much more effective overall than those using normobaric hypoxia (breathing, <20.9% oxygen).

Concepts: Endurance, Effectiveness, Hypoxia, Altitude training, High altitude wind power, Oxygen, Altitude, Altitude sickness

23

The purpose of this study was to evaluate the effect of altitude on rates of ADHD. As decreased dopamine (DA) activity has been reported with ADHD and hypoxia has shown to be associated with increased DA, we hypothesized that states at higher altitudes would have lower rates of ADHD.

Concepts: Altitude sickness, Attention-deficit hyperactivity disorder, Altitude

13

Unmanned aerial vehicles (UAVs) combined with different spectral range sensors are an emerging technology for providing early weed maps for optimizing herbicide applications. Considering that weeds, at very early phenological stages, are similar spectrally and in appearance, three major components are relevant: spatial resolution, type of sensor and classification algorithm. Resampling is a technique to create a new version of an image with a different width and/or height in pixels, and it has been used in satellite imagery with different spatial and temporal resolutions. In this paper, the efficiency of resampled-images (RS-images) created from real UAV-images (UAV-images; the UAVs were equipped with two types of sensors, i.e., visible and visible plus near-infrared spectra) captured at different altitudes is examined to test the quality of the RS-image output. The performance of the object-based-image-analysis (OBIA) implemented for the early weed mapping using different weed thresholds was also evaluated. Our results showed that resampling accurately extracted the spectral values from high spatial resolution UAV-images at an altitude of 30 m and the RS-image data at altitudes of 60 and 100 m, was able to provide accurate weed cover and herbicide application maps compared with UAV-images from real flights.

Concepts: Google Maps, Evaluation, Helicopter, Altitude, Weed, Height, Unmanned aerial vehicle

8

Study Design Retrospective epidemiologic investigation. Objective To investigate the relationship between altitude and concussion rate in the National Football League (NFL). Because of the physiologic responses that occur during acclimatization to altitude, it was hypothesized that games played on fields at a higher altitude would have reduced concussion rates compared to games played on fields at a lower altitude. Background Recent research indicates that the elevation above sea level at which football games are played may be associated with the likelihood of a concussion in high school football athletes. Methods Data on incident concussions and athlete exposures for the first 16 weeks of the NFL 2012 and 2013 regular seasons were obtained from publicly available web-based sources and used to calculate competition concussion rates for each NFL stadium. Concussion rates were analyzed in relation to game elevation. Results During the first 16 weeks of the 2012 and 2013 NFL regular seasons, 300 concussions, involving 284 players, were reported (64.3 primary cases per 10 000 game exposures). The odds of a concussion were 30% lower when playing at a higher elevation (equal to or greater than 644 ft [196.3 m] above sea level) compared to a lower elevation (odds ratio = 0.70; 95% confidence interval: 0.53, 0.94). A multivariable generalized linear model controlling for season, week, and clustering of team at home and away confirmed these results, showing that the odds of at least 1 concussion were reduced by 32% in games played at higher elevation. Conclusion The results of this epidemiological investigation indicate that increased altitude was associated with a reduction in the odds of a sport-related concussion in NFL athletes. The reported relationship of concussion incidence and field elevation should be further investigated, and, if verified, further work will be needed to understand why that relationship exists. Level of Evidence Prognosis, level 2c. J Orthop Sports Phys Ther, Epub 28 January 2014. doi:10.2519/jospt.2014.5298.

Concepts: Concussion, Altitude, Topography, Elevation, High school football, American football, Epidemiology, National Football League

7

Performance in athletic activities that include a significant aerobic component at mild or moderate altitudes shows a large individual variation. Physiologically, a large portion of the negative effect of altitude on exercise performance can be traced to limitations of oxygen diffusion, either at the level of the alveoli or the muscle microvasculature. In the lung, the ability to maintain arterial oxyhaemoglobin saturation (SaO2) appears to be a primary factor, ultimately influencing oxygen delivery to the periphery. SaO2 in hypoxia can be defended by increasing ventilatory drive; however, during heavy exercise, many athletes demonstrate limitations to expiratory flow and are unable to increase ventilation in hypoxia. Additionally, increasing ventilatory work in hypoxia may actually be negative for performance, if dyspnoea increases or muscle blood flow is reduced secondary to an increased sympathetic outflow (eg, the muscle metaboreflex response). Taken together, some athletes are clearly more negatively affected during exercise in hypoxia than other athletes. With careful screening, it may be possible to develop a protocol for determining which athletes may be the most negatively affected during competition and/or training at altitude.

Concepts: Altitude, Blood, Respiratory physiology, Heart, Oxygen, Altitude sickness, Emphysema, Hemoglobin

6

The data reported in this paper are among the first relating to the microbiology of hyper-arid, very high altitude deserts and they provide base line information on the structure of actinobacterial communities. The high mountain Cerro Chajnantor landscape of the Central Andes in northern Chile is exposed to the world’s most intense levels of solar radiation and its impoverished soils are severely desiccated. The purpose of this research was to define the actinobacterial community structures in soils at altitudes ranging from 3000 to 5000 m above sea level. Pyrosequencing surveys have revealed an extraordinary degree of microbial dark matter at these elevations that includes novel candidate actinobacterial classes, orders and families. Ultraviolet-B irradiance and a range of edaphic factors were found to be highly significant in determining community compositions at family and genus levels of diversity.

Concepts: Water, Altitude, Elevation, Topography

4

Study Design Retrospective cohort. Background Participating in sports at high altitude may have a protective effect on the brain according to research studies. Research using validated data collection methods in a previously unexplored cohort may better estimate the association between concussion injury risk and altitude. Objectives To determine the association between concussion rates and altitude during college football games. Methods Athletic trainers from 21 Division I football programs provided exposure and injury data to the NCAA Injury Surveillance Program from the 2009/10 to 2013/14 academic years. Elevations for each stadium were determined. Concussion rates per 1000 athlete-exposures (AEs) were compared in two ways based on our sample of stadium elevations: 1) median split (elevation >178 m vs. <178 m); and 2) quartile split. Rate ratios (RR), rate differences, and 95% confidence intervals (CI) were computed. Results 169 concussions were reported over 49040 AE (3.45/1000 AEs). Using the median split, the concussion rate above 178 m (4.18/1000 AEs) was 1.47 times the concussion rate below 178 m (2.84/1000 AEs; RR 95% CI: 1.09, 2.00; P=0.01). The concussion rate at the highest altitude quartile (>284 m; 5.01/1000 AEs) was 1.67 times greater than the concussion rate at the lowest altitude quartile (<43 m; 3.00/1000 AEs; RR 95% CI: 1.13, 2.48; P=0.01). Conclusion College football game concussion rates appear to increase at higher altitudes. The clinical significance of this relatively small increase is unknown. Future research should explore potential physiologic underpinnings associated with concussion risk at relatively higher and lower altitudes. Level of Evidence Prognosis, level 2b. J Orthop Sports Phys Ther, Epub 11 Jan 2016. doi:10.2519/jospt.2016.6315.

Concepts: High altitude wind power, American football, Football, Topography, Altitude, Concussion, College football, Elevation

3

Reno, Elaine, Talia L. Brown, Marian E. Betz, Michael H. Allen, Lilian Hoffecker, Jeremy Reitinger, Robert Roach, and Benjamin Honigman. Suicide and high altitude: an integrative review. High Alt Med Biol 00:000-000, 2017.

Concepts: Altitude sickness, Altitude, American film actors, High altitude wind power

3

Experimental mesocosm studies of rocky shore and estuarine intertidal systems may benefit from the application of natural tide cycles to better replicate variation in immersion time, water depth, and attendant fluctuations in abiotic and edaphic conditions. Here we describe a stand-alone microcontroller tide prediction open-source software program, coupled with a mechanical tidal elevation control system, which allows continuous adjustment of aquarium water depths in synchrony with local tide cycles. We used this system to monitor the growth of Spartina foliosa marsh cordgrass and scale insect herbivores at three simulated shore elevations in laboratory mesocosms. Plant growth decreased with increasing shore elevation, while scale insect population growth on the plants was not strongly affected by immersion time. This system shows promise for a range of laboratory mesocosm studies where natural tide cycling could impact organism performance or behavior, while the tide prediction system could additionally be utilized in field experiments where treatments need to be applied at certain stages of the tide cycle.

Concepts: Altitude, Tide, Intertidal ecology, Water, Intertidal zone, Plant, Experiment, Geodesy