Search results for "High altitude"
showing 10 items of 26 documents
UVER and UV index at high altitude in Northwestern Argentina
2016
Measurements of ultraviolet erythemal radiation (UVER) made during two years at three sites located at altitudes over 1000 m a.s.l. in Northwestern Argentina (Salta, San Carlos, and El Rosal) have been used to estimate and analyze the UV Index (UVI) and the cumulative doses at these locations. For the UVER irradiance, data of January (maximum values) and June (minimum values) have been analyzed as representative of the year for all locations. The UVI reaches extreme (> 11) values in > 20% of the analyzed days in Salta (1190 m a.s.l.), while these are reached in San Carlos (1611 m a.s.l.) and El Rosal (3355 m a.s.l.) in > 40% of the analyzed days. Finally, the cumulative doses over an averag…
The genomic sequence of Exiguobacterium chiriqhucha str. N139 reveals a species that thrives in cold waters and extreme environmental conditions
2017
We report the genome sequence of Exiguobacterium chiriqhucha str. N139, isolated from a high-altitude Andean lake. Comparative genomic analyses of the Exiguobacterium genomes available suggest that our strain belongs to the same species as the previously reported E. pavilionensis str. RW-2 and Exiguobacterium str. GIC 31. We describe this species and propose the chiriqhucha name to group them. ‘Chiri qhucha’ in Quechua means ‘cold lake’, which is a common origin of these three cosmopolitan Exiguobacteria. The 2,952,588-bp E. chiriqhucha str. N139 genome contains one chromosome and three megaplasmids. The genome analysis of the Andean strain suggests the presence of enzymes that confer E. ch…
Changes of coagulation parameters during high altitude expedition
2010
Data on changes of haemostatic parameters at altitudes above 5000 m are very limited. So far it is unknown, whether altered coagulation could contribute to the development of acute mountain sickness.Thirty four healthy mountaineers were randomised to two acclimatisation protocols and undertook an expedition on Muztagh Ata (7549 m) in China. Tests were performed at five altitudes up to 6865 m. Haemostatic parameters, such as PT, aPTT, D-Dimer, APC-Resistance (APCR), von Willebrand Factor activity (RCo), ADAMTS-13C-Natriuretic Peptide (CNP) were assessed together with Lake Louise AMS score.D-Dimer significantly increased with increasing altitude (median 0.62 to 0.81 mcg/L, p0.0001). During as…
Plasma leptin and vascular endothelial growth factor (VEGF) in normal subjects at high altitude (5050 m)
2013
Context: High altitude (HA) is a model of severe hypoxia exposure in humans. We hypothesized that nocturnal hypoxemia or acute maximal exercise at HA might affect plasma leptin and VEGF levels. Objectives: Plasma leptin, VEGF and other metabolic variables were studied after nocturnal pulse oximetry and after maximal exercise in healthy lowlanders on the 3rd-4th day of stay in Lobuche (5050 m, HA) and after return to sea level (SL). Results: Leptin was similar at SL or HA in both pre- and post-exercise conditions. Pre-exercise VEGF at HA was lower, and cortisol was higher, than at SL, suggesting that nocturnal intermittent hypoxia associated with periodic breathing at HA might affect these v…
Testing Individual Risk of Acute Mountain Sickness at Greater Altitudes
2009
The assessment of an individual's degree of acclimatization to altitude is difficult. This is particularly applicable to military operations that have to be performed at altitude. This study describes a new and simple test that allows for the determination of an individual's risk for high-altitude illness at higher altitudes. The prediction is based on the lowest oxygen saturation (SaO2) found during an uphill run at high altitude (11,060 ft [3,371 m]), combined with the time needed to complete the run. The test results were compared against the severity of high-altitude symptomatology on the summit of Mont Blanc (15,762 ft [4,808 m]). The main outcome was the significant correlation betwee…
Impact of Energy Availability, Health, and Sex on Hemoglobin-Mass Responses Following Live-High-Train-High Altitude Training in Elite Female and Male…
2018
Purpose: The authors investigated the effects of sex, energy availability (EA), and health status on the change in hemoglobin mass (ΔHbmass) in elite endurance athletes over ∼3–4 wk of live-high–train-high altitude training in Flagstaff, AZ (2135 m; n = 27 women; n = 21 men; 27% 2016 Olympians). Methods: Precamp and postcamp Hbmass (optimized carbon monoxide rebreathing method) and iron status were measured, EA was estimated via food and training logs, and a Low Energy Availability in Females Questionnaire (LEAFQ) and a general injury/illness questionnaire were completed. Hypoxic exposure (h) was calculated with low (<500 h), moderate (500–600 h), and high (>600 h) groupings. Results:…
Exercise intolerance at high altitude (5050 m): critical power and W'.
2011
Abstract The relationship between work rate (WR) and its tolerable duration (tLIM) has not been investigated at high altitude (HA). At HA (5050 m) and at sea level (SL), six subjects therefore performed symptom-limited cycle-ergometry: an incremental test (IET) and three constant-WR tests (% of IET WRmax, HA and SL respectively: WR1 70 ± 8%, 74 ± 7%; WR2 86 ± 14%, 88 ± 10%; WR3 105 ± 13%, 104 ± 9%). The power asymptote (CP) and curvature constant (W′) of the hyperbolic WR–tLIM relationship were reduced at HA compared to SL (CP: 81 ± 21 vs. 123 ± 38 W; W′: 7.2 ± 2.9 vs. 13.1 ± 4.3 kJ). HA breathing reserve (estimated maximum voluntary ventilation minus end-exercise ventilation) was also comp…
Improvement in altitude performance test after further acclimatization in pre-acclimatized soldiers.
2013
The Altitude Performance Test is a measure designed to assess an individual's degree of acclimatization to reduce the risk of acute mountain sickness during high-altitude activities. The aim of this study was to investigate the hypothesis that test results will improve in pre-acclimatized soldiers after several days of further acclimatization. The Altitude Performance Test consists of an uphill run at high altitude. The event is timed and performed with continuous oxygen saturation (SpO2) monitoring. The individual's time and lowest SpO2 measurement are recorded. This test was performed on the first day of arriving at 11,060 ft, and after 9 days at the same location. The 37 male soldiers we…
Characteristics of the early flight phase in the Olympic ski jumping competition.
2004
Early flight phase (approximately 40 m) of the athletes participating in the final round of the individual large hill ski jumping competition in Salt Lake City Olympics was filmed with two high-speed pan & tilt video cameras. The results showed that jumpers' steady flight position was almost completed within 0.5s. The most significant correlation with the length of the jump was found in the angle between the skis and body (r=.714, p.001 at 1.1s after the take-off). This particular phase seemed to be important because the ski angle of attack was also related to the jumping distance at the same phase. Although the more upright ski position relative to flight path resulted in longer jumping di…
SOUTHTRAC-GW: An airborne field campaign to explore gravity wave dynamics at the world’s strongest hotspot
2021
The southern part of South America and the Antarctic peninsula are known as the world’s strongest hotspot region of stratospheric gravity wave (GW) activity. Large tropospheric winds are deflected by the Andes and the Antarctic Peninsula and excite GWs that might propagate into the upper mesosphere. Satellite observations show large stratospheric GW activity above the mountains, the Drake Passage, and in a belt centered along 60°S. This scientifically highly interesting region for studying GW dynamics was the focus of the Southern Hemisphere Transport, Dynamics, and Chemistry–Gravity Waves (SOUTHTRAC-GW) mission. The German High Altitude and Long Range Research Aircraft (HALO) was deployed …