The sleep of elite athletes at sea level and high altitude: a comparison of sea-level natives and high-altitude natives (ISA3600)

PubMed Central

Roach, Gregory D; Schmidt, Walter F; Aughey, Robert J; Bourdon, Pitre C; Soria, Rudy; Claros, Jesus C Jimenez; Garvican-Lewis, Laura A; Buchheit, Martin; Simpson, Ben M; Hammond, Kristal; Kley, Marlen; Wachsmuth, Nadine; Gore, Christopher J; Sargent, Charli

2013-01-01

Background Altitude exposure causes acute sleep disruption in non-athletes, but little is known about its effects in elite athletes. The aim of this study was to examine the effects of altitude on two groups of elite athletes, that is, sea-level natives and high-altitude natives. Methods Sea-level natives were members of the Australian under-17 soccer team (n=14). High-altitude natives were members of a Bolivian under-20 club team (n=12). Teams participated in an 18-day (19 nights) training camp in Bolivia, with 6 nights at near sea level in Santa Cruz (430 m) and 13 nights at high altitude in La Paz (3600 m). Sleep was assessed on every day/night using activity monitors. Results The Australians’ sleep was shorter, and of poorer quality, on the first night at altitude compared with sea level. Sleep quality returned to normal by the end of the first week at altitude, but sleep quantity had still not stabilised at its normal level after 2 weeks. The quantity and quality of sleep obtained by the Bolivians was similar, or greater, on all nights at altitude compared with sea level. The Australians tended to obtain more sleep than the Bolivians at sea level and altitude, but the quality of the Bolivians’ sleep tended to be better than that of the Australians at altitude. Conclusions Exposure to high altitude causes acute and chronic disruption to the sleep of elite athletes who are sea-level natives, but it does not affect the sleep of elite athletes who are high-altitude natives. PMID:24282197

The Impact of Altitude on Sleep-Disordered Breathing in Children Dwelling at High Altitude: A Crossover Study.

PubMed

Hughes, Benjamin H; Brinton, John T; Ingram, David G; Halbower, Ann C

2017-09-01

Sleep-disordered breathing (SDB) is prevalent among children and is associated with adverse health outcomes. Worldwide, approximately 250 million individuals reside at altitudes higher than 2000 meters above sea level (masl). The effect of chronic high-altitude exposure on children with SDB is unknown. This study aims to determine the impact of altitude on sleep study outcomes in children with SDB dwelling at high altitude. A single-center crossover study was performed to compare results of high-altitude home polysomnography (H-PSG) with lower altitude laboratory polysomnography (L-PSG) in school-age children dwelling at high altitude with symptoms consistent with SDB. The primary outcome was apnea-hypopnea index (AHI), with secondary outcomes including obstructive AHI; central AHI; and measures of oxygenation, sleep quality, and pulse rate. Twelve participants were enrolled, with 10 included in the final analysis. Median altitude was 1644 masl on L-PSG and 2531 masl on H-PSG. Median AHI was 2.40 on L-PSG and 10.95 on H-PSG. Both obstructive and central respiratory events accounted for the difference in AHI. Oxygenation and sleep fragmentation were worse and pulse rate higher on H-PSG compared to L-PSG. These findings reveal a clinically substantial impact of altitude on respiratory, sleep, and cardiovascular outcomes in children with SDB who dwell at high altitude. Within this population, L-PSG underestimates obstructive sleep apnea and central sleep apnea compared to H-PSG. Given the shortage of high-altitude pediatric sleep laboratories, these results suggest a role for home sleep apnea testing for children residing at high altitude. © Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

The sleep of elite athletes at sea level and high altitude: a comparison of sea-level natives and high-altitude natives (ISA3600).

PubMed

Roach, Gregory D; Schmidt, Walter F; Aughey, Robert J; Bourdon, Pitre C; Soria, Rudy; Claros, Jesus C Jimenez; Garvican-Lewis, Laura A; Buchheit, Martin; Simpson, Ben M; Hammond, Kristal; Kley, Marlen; Wachsmuth, Nadine; Gore, Christopher J; Sargent, Charli

2013-12-01

Altitude exposure causes acute sleep disruption in non-athletes, but little is known about its effects in elite athletes. The aim of this study was to examine the effects of altitude on two groups of elite athletes, that is, sea-level natives and high-altitude natives. Sea-level natives were members of the Australian under-17 soccer team (n=14). High-altitude natives were members of a Bolivian under-20 club team (n=12). Teams participated in an 18-day (19 nights) training camp in Bolivia, with 6 nights at near sea level in Santa Cruz (430 m) and 13 nights at high altitude in La Paz (3600 m). Sleep was assessed on every day/night using activity monitors. The Australians' sleep was shorter, and of poorer quality, on the first night at altitude compared with sea level. Sleep quality returned to normal by the end of the first week at altitude, but sleep quantity had still not stabilised at its normal level after 2 weeks. The quantity and quality of sleep obtained by the Bolivians was similar, or greater, on all nights at altitude compared with sea level. The Australians tended to obtain more sleep than the Bolivians at sea level and altitude, but the quality of the Bolivians' sleep tended to be better than that of the Australians at altitude. Exposure to high altitude causes acute and chronic disruption to the sleep of elite athletes who are sea-level natives, but it does not affect the sleep of elite athletes who are high-altitude natives.

Athletes at High Altitude

PubMed Central

Khodaee, Morteza; Grothe, Heather L.; Seyfert, Jonathan H.; VanBaak, Karin

2016-01-01

Context: Athletes at different skill levels perform strenuous physical activity at high altitude for a variety of reasons. Multiple team and endurance events are held at high altitude and may place athletes at increased risk for developing acute high altitude illness (AHAI). Training at high altitude has been a routine part of preparation for some of the high level athletes for a long time. There is a general belief that altitude training improves athletic performance for competitive and recreational athletes. Evidence Acquisition: A review of relevant publications between 1980 and 2015 was completed using PubMed and Google Scholar. Study Design: Clinical review. Level of Evidence: Level 3. Results: AHAI is a relatively uncommon and potentially serious condition among travelers to altitudes above 2500 m. The broad term AHAI includes several syndromes such as acute mountain sickness (AMS), high altitude pulmonary edema (HAPE), and high altitude cerebral edema (HACE). Athletes may be at higher risk for developing AHAI due to faster ascent and more vigorous exertion compared with nonathletes. Evidence regarding the effects of altitude training on athletic performance is weak. The natural live high, train low altitude training strategy may provide the best protocol for enhancing endurance performance in elite and subelite athletes. High altitude sports are generally safe for recreational athletes, but they should be aware of their individual risks. Conclusion: Individualized and appropriate acclimatization is an essential component of injury and illness prevention. PMID:26863894

14 CFR 23.1527 - Maximum operating altitude.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Maximum operating altitude. 23.1527 Section... Information § 23.1527 Maximum operating altitude. (a) The maximum altitude up to which operation is allowed... established. (b) A maximum operating altitude limitation of not more than 25,000 feet must be established for...

Genotype by environment interaction for growth due to altitude in United States Angus cattle.

PubMed

Williams, J L; Bertrand, J K; Misztal, I; Łukaszewicz, M

2012-07-01

The objectives of this study were to determine if sires perform consistently across altitude and to quantify the genetic relationship between growth and survival at differing altitudes. Data from the American Angus Association included weaning weight (WW) adjusted to 205 (n = 77,771) and yearling weight adjusted to 365 (n = 39,450) d of age from 77,771 purebred Angus cattle born in Colorado between 1972 and 2007. Postweaning gain (PWG) was calculated by subtracting adjusted WW from adjusted yearling weight. Altitude was assigned to each record based upon the zip code of each herd in the database. Records for WW and PWG were each split into 2 traits measured at low and high altitude, with the records from medium altitude removed from the data due to inconsistencies between growth performance and apparent culling rate. A binary trait, survival (SV), was defined to account for censored records at yearling for each altitude. It was assumed that, at high altitude, individuals missing a yearling weight either died or required relocation to a lower altitude predominantly due to brisket disease, a condition common at high altitude. Model 1 considered each WW and PWG measured at 2 altitudes as separate traits. Model 2 treated PWG and SV measured as separate traits due to altitude. Models included the effects of weaning contemporary group, age of dam, animal additive genetic effects, and residual. Maternal genetic and maternal permanent environmental effects were included for WW. Heritability estimates for WW in Model 1 were 0.28 and 0.26 and for PWG were 0.26 and 0.19 with greater values in low altitude. Genetic correlations between growth traits measured at different altitude were moderate in magnitude: 0.74 for WW and 0.76 for PWG and indicate possibility of reranking of sires across altitude. Maternal genetic correlation between WW at varying altitude of 0.75 also indicates these may be different traits. In Model 2, heritabilities were 0.14 and 0.27 for PWG and 0.36 and 0.47 for SV. Genetic correlation between PWG measured at low and high altitude was 0.68. Favorable genetic correlations were estimated between SV and PWG within and between altitudes, suggesting that calves with genetics for increased growth from weaning to yearling also have increased genetic potential for SV. Genetic evaluations of PWG in different altitudes should consider preselection of the data, by using a censoring trait, like survivability to yearling.

Altitude-Related Illness: Advice to Travellers

PubMed Central

Crutcher, Rodney A.

1990-01-01

Altitude-related medical problems have received much attention in the recent medical literature. Family physicians must be knowledgeable about these problems so that they can give appropriate advice to travellers. The author, a practising family physician, discusses issues arising from both the modest cabin altitudes experienced in modern-day air travel and the greater altitudes experienced by skiers and trekkers, pilots and mountaineers, and lowland adventurers of all sorts. He reviews the process of acclimatization to altitude and the four principal forms of altitude illness. PMID:21233912

Altitude Stress During Participation of Medical Congress

PubMed Central

Kim, Soon Bae; Kim, Jong Sung; Kim, Sang Jun; Cho, Su Hee

2016-01-01

Medical congresses often held in highlands. We reviewed several medical issues associated with altitude stress especially while physicians have participated medical congress held in high altitude. Altitude stress, also known as an acute mountain sickness (AMS), is caused by acute exposure to low oxygen level at high altitude which is defined as elevations at or above 1,200 m and AMS commonly occurs above 2,500 m. Altitude stress with various symptoms including insomnia can also be experienced in airplane. AMS and drunken state share many common features in symptoms, neurologic manifestations and even show multiple microbleeds in corpus callosum and white matter on MRI. Children are more susceptible to altitude stress than adults. Gradual ascent is the best method for the prevention of altitude stress. Adequate nutrition (mainly carbohydrates) and hydration are recommended. Consumption of alcohol can exacerbate the altitude-induced impairments in judgment and the visual senses and promote psychomotor dysfunction. For prevention or treatment of altitude stress, acetazolamide, phosphodiesterase inhibitors, dexamethasone and erythropoietin are helpful. Altitude stress can be experienced relatively often during participation of medical congress. It is necessary to remind the harmful effect of AMS because it can cause serious permanent organ damage even though the symptoms are negligible in most cases. PMID:27621942

Short-term responses of the kidney to high altitude in mountain climbers

PubMed Central

Goldfarb-Rumyantzev, Alexander S.; Alper, Seth L.

2014-01-01

In high-altitude climbers, the kidneys play a crucial role in acclimatization and in mountain sickness syndromes [acute mountain sickness (AMS), high-altitude cerebral edema, high-altitude pulmonary edema] through their roles in regulating body fluids, electrolyte and acid–base homeostasis. Here, we discuss renal responses to several high-altitude-related stresses, including changes in systemic volume status, renal plasma flow and clearance, and altered acid–base and electrolyte status. Volume regulation is considered central both to high-altitude adaptation and to maladaptive development of mountain sickness. The rapid and powerful diuretic response to the hypobaric hypoxic stimulus of altitude integrates decreased circulating concentrations of antidiuretic hormone, renin and aldosterone, increased levels of natriuretic hormones, plasma and urinary epinephrine, norepinephrine, endothelin and urinary adrenomedullin, with increased insensible fluid losses and reduced fluid intake. The ventilatory and hormonal responses to hypoxia may predict susceptibility to AMS, also likely influenced by multiple genetic factors. The timing of altitude increases and adaptation also modifies the body's physiologic responses to altitude. While hypovolemia develops as part of the diuretic response to altitude, coincident vascular leak and extravascular fluid accumulation lead to syndromes of high-altitude sickness. Pharmacological interventions, such as diuretics, calcium blockers, steroids, phosphodiesterase inhibitors and β-agonists, may potentially be helpful in preventing or attenuating these syndromes. PMID:23525530

40 CFR 600.310-86 - Labeling of high altitude vehicles.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 30 2011-07-01 2011-07-01 false Labeling of high altitude vehicles... Regulations for 1977 and Later Model Year Automobiles-Labeling § 600.310-86 Labeling of high altitude vehicles... altitude vehicles according to § 600.306. (b) A high altitude vehicle may be labeled with a general or...

40 CFR 600.310-86 - Labeling of high altitude vehicles.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Labeling of high altitude vehicles... Regulations for 1977 and Later Model Year Automobiles-Labeling § 600.310-86 Labeling of high altitude vehicles... altitude vehicles according to § 600.306. (b) A high altitude vehicle may be labeled with a general or...

Training at altitude in practice.

PubMed

Dick, F W

1992-10-01

There can be little doubt that training at altitude is fundamental to preparing an athlete for competition at altitude. However the value of training at altitude for competition at sea level appears on the one hand to lack total acceptance amongst sports scientists; and on the other to hold some cloak of mystery for coaches who have yet to enjoy first hand experience. The fact is that very few endurance athletes will ignore the critical edge which altitude training affords. Each fraction of a percentage of performance advantage gained through methods which are within the rules of fair play in sport, may shift the balance between failure and achievement. Moreover, there is growing support for application of training at altitude for speed-related disciplines. This paper aims to demystify the subject by dealing with practical aspects of training at altitude. Such aspects include a checklist of what should and should not be done at altitude, when to use altitude relative to target competitions, and specific training examples.

First-Order Altitude Effects on the Cruise Efficiency of Subsonic Transport Aircraft

NASA Technical Reports Server (NTRS)

Guynn, Mark D.

2011-01-01

Aircraft fuel efficiency is a function of many different parameters, including characteristics of the engines, characteristics of the airframe, and the conditions under which the aircraft is operated. For a given vehicle, the airframe and engine characteristics are for the most part fixed quantities and efficiency is primarily a function of operational conditions. One important influence on cruise efficiency is cruise altitude. Various future scenarios have been postulated for cruise altitude, from the freedom to fly at optimum altitudes to altitude restrictions imposed for environmental reasons. This report provides background on the fundamental relationships determining aircraft cruise efficiency and examines the sensitivity of efficiency to cruise altitude. Analytical models of two current aircraft designs are used to derive quantitative results. Efficiency penalties are found to be generally less than 1% when within roughly 2000 ft of the optimum cruise altitude. Even the restrictive scenario of constant altitude cruise is found to result in a modest fuel consumption penalty if the fixed altitude is in an appropriate range.

High-Altitude Illnesses: Physiology, Risk Factors, Prevention, and Treatment

PubMed Central

Taylor, Andrew T.

2011-01-01

High-altitude illnesses encompass the pulmonary and cerebral syndromes that occur in non-acclimatized individuals after rapid ascent to high altitude. The most common syndrome is acute mountain sickness (AMS) which usually begins within a few hours of ascent and typically consists of headache variably accompanied by loss of appetite, nausea, vomiting, disturbed sleep, fatigue, and dizziness. With millions of travelers journeying to high altitudes every year and sleeping above 2,500 m, acute mountain sickness is a wide-spread clinical condition. Risk factors include home elevation, maximum altitude, sleeping altitude, rate of ascent, latitude, age, gender, physical condition, intensity of exercise, pre-acclimatization, genetic make-up, and pre-existing diseases. At higher altitudes, sleep disturbances may become more profound, mental performance is impaired, and weight loss may occur. If ascent is rapid, acetazolamide can reduce the risk of developing AMS, although a number of high-altitude travelers taking acetazolamide will still develop symptoms. Ibuprofen can be effective for headache. Symptoms can be rapidly relieved by descent, and descent is mandatory, if at all possible, for the management of the potentially fatal syndromes of high-altitude pulmonary and cerebral edema. The purpose of this review is to combine a discussion of specific risk factors, prevention, and treatment options with a summary of the basic physiologic responses to the hypoxia of altitude to provide a context for managing high-altitude illnesses and advising the non-acclimatized high-altitude traveler. PMID:23908794

Maximization of orbiter altitude at ALT interface airspeed, mission planning, mission analysis and software

NASA Technical Reports Server (NTRS)

Glenn, G. M.

1976-01-01

The determination of the separation initial conditions (i.e. incidence angle) that maximize orbiter altitude at the ALT interface airspeed is considered. Optimum altitude airspeed profiles are generated for each orbiter incidence angle and tailcone configuration. Results show that the highest separation altitude does not result in the highest altitude at ALT interface airspeed. The altitude attainable at ALT interface airspeed should therefore be considered in the selection of the initial conditions (i.e. incidence angle). Without violating any known constraints, the incidence angles that maximize orbiter altitude at the ALT interface airspeeds are 7.0 deg for ALT free flight 1 and 5.5 deg for ALT free flight 6.

40 CFR Appendix C to Subpart S of... - Steady-State Short Test Standards

Code of Federal Regulations, 2011 CFR

2011-07-01

... later model year light-duty vehicles at low altitude and 1982 and later model year vehicles at high altitude to which high altitude certification standards of 1.5 gpm HC and 15 gpm CO or less apply), short... model year light-duty trucks at low altitude and 1982 and later model year trucks at high altitude to...

The Role of Visual Occlusion in Altitude Maintenance during Simulated Flight

ERIC Educational Resources Information Center

Gray, R.; Geri, G. A.; Akhtar, S. C.; Covas, C. M.

2008-01-01

The use of visual occlusion as a cue to altitude maintenance in low-altitude flight (LAF) was investigated. The extent to which the ground surface is occluded by 3-D objects varies with altitude and depends on the height, radius, and density of the objects. Participants attempted to maintain a constant altitude during simulated flight over an…

The pulmonary circulation of some domestic animals at high altitude

NASA Astrophysics Data System (ADS)

Anand, I.; Heath, D.; Williams, D.; Deen, M.; Ferrari, R.; Bergel, D.; Harris, P.

1988-03-01

Pulmonary haemodynamics and the histology of the pulmonary vasculature have been studied at high altitude in the yak, in interbreeds between yaks and cattle, and in domestic goats and sheep indigenous to high altitudes together with crosses between them and low-altitude strains. Cattle at high altitude had a higher pulmonary arterial pressure than cattle at low altitude. The yak and two interbreeds with cattle (dzos and stols) had a low pulmonary arterial pressure compared with cattle, while the medial thickness of the small pulmonary arteries was less than would be expected in cattle, suggesting that the yak has a low capacity for hypoxic pulmonary vasoconstriction and that this characteristic is transmitted genetically. Goats and sheep showed haemodynamic evidence of a limited response of the pulmonary circulation to high altitude, but no evidence that the high altitude breeds had lost this response. There were no measurable differences in the thickness of the media of the small pulmonary arteries between high- and low-altitude breeds of goats and sheep. All these species showed prominent intimal protrusions of muscle into the pulmonary veins but no specific effect of high altitude in this respect.

Altitude-Related Change in Endotracheal Tube Cuff Pressures in Helicopter EMS

PubMed Central

Weisberg, Stacy N.; McCall, Jonathan C.; Tennyson, Joseph

2017-01-01

Introduction Over-inflation of endotracheal tube (ETT) cuffs has the potential to lead to scarring and stenosis of the trachea.1, 2,3, 4 The air inside an ETT cuff is subject to expansion as atmospheric pressure decreases, as happens with an increase in altitude. Emergency medical services helicopters are not pressurized, thereby providing a good environment for studying the effects of altitude changes ETT cuff pressures. This study aims to explore the relationship between altitude and ETT cuff pressures in a helicopter air-medical transport program. Methods ETT cuffs were initially inflated in a nonstandardized manner and then adjusted to a pressure of 25 cmH2O. The pressure was again measured when the helicopter reached maximum altitude. A final pressure was recorded when the helicopter landed at the receiving facility. Results We enrolled 60 subjects in the study. The mean for initial tube cuff pressures was 70 cmH2O. Maximum altitude for the program ranged from 1,000–3,000 feet above sea level, with a change in altitude from 800–2,480 feet. Mean cuff pressure at altitude was 36.52 ± 8.56 cmH2O. Despite the significant change in cuff pressure at maximum altitude, there was no relationship found between the maximum altitude and the cuff pressures measured. Conclusion Our study failed to demonstrate the expected linear relationship between ETT cuff pressures and the maximum altitude achieved during typical air-medical transportation in our system. At altitudes less than 3,000 feet above sea level, the effect of altitude change on ETT pressure is minimal and does not require a change in practice to saline-filled cuffs. PMID:28611883

Altitude matters: differences in cardiovascular and respiratory responses to hypoxia in bar-headed geese reared at high and low altitudes.

PubMed

Lague, Sabine L; Chua, Beverly; Farrell, Anthony P; Wang, Yuxiang; Milsom, William K

2016-07-01

Bar-headed geese (Anser indicus) fly at high altitudes during their migration across the Himalayas and Tibetan plateau. However, we know relatively little about whether rearing at high altitude (i.e. phenotypic plasticity) facilitates this impressive feat because most of what is known about their physiology comes from studies performed at sea level. To provide this information, a comprehensive analysis of metabolic, cardiovascular and ventilatory responses to progressive decreases in the equivalent fractional composition of inspired oxygen (FiO2 : 0.21, 0.12, 0.09, 0.07 and 0.05) was made on bar-headed geese reared at either high altitude (3200 m) or low altitude (0 m) and on barnacle geese (Branta leucopsis), a low-altitude migrating species, reared at low altitude (0 m). Bar-headed geese reared at high altitude exhibited lower metabolic rates and a modestly increased hypoxic ventilatory response compared with low-altitude-reared bar-headed geese. Although the in vivo oxygen equilibrium curves and blood-oxygen carrying capacity did not differ between the two bar-headed goose study groups, the blood-oxygen carrying capacity was higher than that of barnacle geese. Resting cardiac output also did not differ between groups and increased at least twofold during progressive hypoxia, initially as a result of increases in stroke volume. However, cardiac output increased at a higher FiO2  threshold in bar-headed geese raised at high altitude. Thus, bar-headed geese reared at high altitude exhibited a reduced oxygen demand at rest and a modest but significant increase in oxygen uptake and delivery during progressive hypoxia compared with bar-headed geese reared at low altitude. © 2016. Published by The Company of Biologists Ltd.

Propofol-fentanyl anaesthesia at high altitude: anaesthetic requirements and haemodynamic variations when compared with anaesthesia at low altitude.

PubMed

Puri, G D; Jayant, A; Dorje, M; Tashi, M

2008-03-01

There are few published accounts of anaesthesia delivery at high altitude. Natives at high altitude are known to have altered cardiorespiratory reserve. This study seeks to demonstrate the safety of propofol-fentanyl anaesthesia at high altitude titrated to the bispectral index (BIS) (3505 metres above sea level) in native highlanders. It also shows the differential effects of anaesthesia and surgery on the haemodynamics of such individuals as compared with individuals living at low altitude. Fifteen consenting adults scheduled to undergo general surgical/orthopaedic procedures under general anaesthesia using fentanyl, and propofol infusions titrated to the BIS along with nitrous oxide in oxygen after intubation, were recruited in the high-altitude arm. Their anaesthesia record was compared with retrospective data from low altitude with respect to anaesthetic requirements, recovery after anaesthesia and the haemodynamic responses to surgical stress. The high-altitude dwellers required significantly larger doses of propofol at anaesthetic induction (2.31+/-0.64 vs. 1.41+/-0.24 mg/kg, P<0.0001) and thereafter to maintain designated BIS than their low-altitude counterparts (6.22+/-1.14 vs. 4.61+/-1.29 mg/kg/h, P<0.01). They, however, had uneventful and short recovery times. The high-altitude population also had significantly lower baseline heart rates (72+/-9.83 vs. 88+/-12.1, P<0.04) as also the heart rate responses to noxious stimulation such as direct laryngoscopy or skin incision (P<0.04, P<0.005, respectively). High-altitude dwellers require significantly larger amounts of intravenous anaesthetic propofol. Heart rate at rest as also the heart rate responses to surgical stress were significantly attenuated at high altitude.

Altitude-Related Change in Endotracheal Tube Cuff Pressures in Helicopter EMS.

PubMed

Weisberg, Stacy N; McCall, Jonathan C; Tennyson, Joseph

2017-06-01

Over-inflation of endotracheal tube (ETT) cuffs has the potential to lead to scarring and stenosis of the trachea.1, 2,3, 4 The air inside an ETT cuff is subject to expansion as atmospheric pressure decreases, as happens with an increase in altitude. Emergency medical services helicopters are not pressurized, thereby providing a good environment for studying the effects of altitude changes ETT cuff pressures. This study aims to explore the relationship between altitude and ETT cuff pressures in a helicopter air-medical transport program. ETT cuffs were initially inflated in a nonstandardized manner and then adjusted to a pressure of 25 cmH 2 O. The pressure was again measured when the helicopter reached maximum altitude. A final pressure was recorded when the helicopter landed at the receiving facility. We enrolled 60 subjects in the study. The mean for initial tube cuff pressures was 70 cmH 2 O. Maximum altitude for the program ranged from 1,000-3,000 feet above sea level, with a change in altitude from 800-2,480 feet. Mean cuff pressure at altitude was 36.52 ± 8.56 cmH 2 O. Despite the significant change in cuff pressure at maximum altitude, there was no relationship found between the maximum altitude and the cuff pressures measured. Our study failed to demonstrate the expected linear relationship between ETT cuff pressures and the maximum altitude achieved during typical air-medical transportation in our system. At altitudes less than 3,000 feet above sea level, the effect of altitude change on ETT pressure is minimal and does not require a change in practice to saline-filled cuffs.

Adaptation to Life in the High Andes: Nocturnal Oxyhemoglobin Saturation in Early Development.

PubMed

Hill, Catherine Mary; Baya, Ana; Gavlak, Johanna; Carroll, Annette; Heathcote, Kate; Dimitriou, Dagmara; L'Esperance, Veline; Webster, Rebecca; Holloway, John; Virues-Ortega, Javier; Kirkham, Fenella Jane; Bucks, Romola Starr; Hogan, Alexandra Marie

2016-05-01

Physiological adaptation to high altitude hypoxia may be impaired in Andeans with significant European ancestry. The respiratory 'burden' of sleep may challenge adaptation, leading to relative nocturnal hypoxia. Developmental aspects of sleep-related breathing in high-altitude native children have not previously been reported. We aimed to determine the influence of development on diurnal-nocturnal oxyhemoglobin differences in children living at high altitude. This was a cross-sectional, observational study. Seventy-five healthy Bolivian children aged 6 mo to 17 y, native to low altitude (500 m), moderate high altitude (2,500 m), and high altitude (3,700 m) were recruited. Daytime resting pulse oximetry was compared to overnight recordings using Masimo radical oximeters. Genetic ancestry was determined from DNA samples. Children had mixed European/Amerindian ancestry, with no significant differences between altitudes. Sixty-two participants had ≥ 5 h of nocturnal, artifact-free data. As predicted, diurnal mean oxyhemoglobin saturation decreased across altitudes (infants and children, both P < 0.001), with lowest diurnal values at high altitude in infants. At high altitude, there was a greater drop in nocturnal mean oxyhemoglobin saturation (infants, P < 0.001; children, P = 0.039) and an increase in variability (all P ≤ 0.001) compared to low altitude. Importantly, diurnal to nocturnal altitude differences diminished (P = 0.036), from infancy to childhood, with no further change during adolescence. Physiological adaptation to high-altitude living in native Andeans is unlikely to compensate for the significant differences we observed between diurnal and nocturnal oxyhemoglobin saturation, most marked in infancy. This vulnerability to sleep-related hypoxia in early childhood has potential lifespan implications. Future studies should characterize the sleep- related respiratory physiology underpinning our observations. © 2016 Associated Professional Sleep Societies, LLC.

NASA aviation safety reporting system

NASA Technical Reports Server (NTRS)

1978-01-01

An analytical study of reports relating to cockpit altitude alert systems was performed. A recent change in the Federal Air Regulation permits the system to be modified so that the alerting signal approaching altitude has only a visual component; the auditory signal would continue to be heard if a deviation from an assigned altitude occurred. Failure to observe altitude alert signals and failure to reset the system were the commonest cause of altitude deviations related to this system. Cockpit crew distraction was the most frequent reason for these failures. It was noted by numerous reporters that the presence of altitude alert system made them less aware of altitude; this lack of altitude awareness is discussed. Failures of crew coordination were also noted. It is suggested that although modification of the altitude alert system may be highly desirable in short-haul aircraft, it may not be desirable for long-haul aircraft in which cockpit workloads are much lower for long periods of time. In these cockpits, the aural alert approaching altitudes is perceived as useful and helpful. If the systems are to be modified, it appears that additional emphasis on altitude awareness during recurrent training will be necessary; it is also possible that flight crew operating procedures during climb and descent may need examination with respect to monitoring responsibilities. A selection of alert bulletins and responses to them is presented.

A Mountain or a Plateau? Hematological Traits Vary Nonlinearly with Altitude in a Highland Lizard.

PubMed

González-Morales, Juan Carlos; Beamonte-Barrientos, Rene; Bastiaans, Elizabeth; Guevara-Fiore, Palestina; Quintana, Erendira; Fajardo, Victor

High-altitude organisms exhibit hematological adaptations to augment blood transport of oxygen. One common mechanism is through increased values of blood traits such as erythrocyte count, hematocrit, and hemoglobin concentration. However, a positive relationship between altitude and blood traits is not observed in all high-altitude systems. To understand how organisms adapt to high altitudes, it is important to document physiological patterns related to hypoxia gradients from a greater variety of species. Here, we present an extensive hematological description for three populations of Sceloporus grammicus living at 2,500, 3,400, and 4,300 m. We did not find a linear increase with altitude for any of the blood traits we measured. Instead, we found nonlinear relationships between altitude and the blood traits erythrocyte number, erythrocyte size, hematocrit, and hemoglobin concentration. Erythrocyte number and hematocrit leveled off as altitude increased, whereas hemoglobin concentration and erythrocyte size were highest at intermediate altitude. Additionally, lizards from our three study populations are similar in blood pH, serum electrolytes, glucose, and lactate. Given that the highest-altitude population did not show the highest levels of the variables we measured, we suggest these lizards may be using different adaptations to cope with hypoxia than lizards at low or intermediate altitudes. We discuss future directions that research could take to investigate such potential adaptations.

Atmospheric Electricity and Tethered Aerostats, Volume 2

DTIC Science & Technology

1976-05-11

vs Altitude (Non- conducting or Conducting Tethers...Effect of Corona Charge Plume 15 3.1 Tether Current vs Balloon Altitude , BJ+3 - 25 Sep 73 20 3.2 Tether Current vs Balloon Altitude , Baldy - 17 Oct 73 21...3.3 Tether Current vs Balloon Altitude , Baldy - 31 Oct 73 22 3.4 Tether Current vs Balloon Altitude , Baldy - 2 Nov 73 23 3.5 Tether Current vs

Altitude and COPD prevalence: analysis of the PREPOCOL-PLATINO-BOLD-EPI-SCAN study.

PubMed

Horner, Andreas; Soriano, Joan B; Puhan, Milo A; Studnicka, Michael; Kaiser, Bernhard; Vanfleteren, Lowie E G W; Gnatiuc, Louisa; Burney, Peter; Miravitlles, Marc; García-Rio, Francisco; Ancochea, Julio; Menezes, Ana M; Perez-Padilla, Rogelio; Montes de Oca, Maria; Torres-Duque, Carlos A; Caballero, Andres; González-García, Mauricio; Buist, Sonia; Flamm, Maria; Lamprecht, Bernd

2017-08-23

COPD prevalence is highly variable and geographical altitude has been linked to it, yet with conflicting results. We aimed to investigate this association, considering well known risk factors. A pooled analysis of individual data from the PREPOCOL-PLATINO-BOLD-EPI-SCAN studies was used to disentangle the population effect of geographical altitude on COPD prevalence. Post-bronchodilator FEV1/FVC below the lower limit of normal defined airflow limitation consistent with COPD. High altitude was defined as >1500 m above sea level. Undiagnosed COPD was considered when participants had airflow limitation but did not report a prior diagnosis of COPD. Among 30,874 participants aged 56.1 ± 11.3 years from 44 sites worldwide, 55.8% were women, 49.6% never-smokers, and 12.9% (3978 subjects) were residing above 1500 m. COPD prevalence was significantly lower in participants living at high altitude with a prevalence of 8.5% compared to 9.9%, respectively (p < 0.005). However, known risk factors were significantly less frequent at high altitude. Hence, in the adjusted multivariate analysis, altitude itself had no significant influence on COPD prevalence. Living at high altitude, however, was associated with a significantly increased risk of undiagnosed COPD. Furthermore, subjects with airflow limitation living at high altitude reported significantly less respiratory symptoms compared to subjects residing at lower altitude. Living at high altitude is not associated with a difference in COPD prevalence after accounting for individual risk factors. However, high altitude itself was associated with an increased risk of undiagnosed COPD.

Study on Oxygen Supply Standard for Physical Health of Construction Personnel of High-Altitude Tunnels.

PubMed

Guo, Chun; Xu, Jianfeng; Wang, Mingnian; Yan, Tao; Yang, Lu; Sun, Zhitao

2015-12-22

The low atmospheric pressure and low oxygen content in high-altitude environment have great impacts on the functions of human body. Especially for the personnel engaged in complicated physical labor such as tunnel construction, high altitude can cause a series of adverse physiological reactions, which may result in multiple high-altitude diseases and even death in severe cases. Artificial oxygen supply is required to ensure health and safety of construction personnel in hypoxic environments. However, there are no provisions for oxygen supply standard for tunnel construction personnel in high-altitude areas in current tunnel construction specifications. As a result, this paper has theoretically studied the impacts of high-altitude environment on human bodies, analyzed the relationship between labor intensity and oxygen consumption in high-altitude areas and determined the critical oxygen-supply altitude values for tunnel construction based on two different standard evaluation systems, i.e., variation of air density and equivalent PIO₂. In addition, it has finally determined the oxygen supply standard for construction personnel in high-altitude areas based on the relationship between construction labor intensity and oxygen consumption.

An Investigation into the Nature of High Altitude Cosmic Radiation in the Stratosphere

ERIC Educational Resources Information Center

Bancroft, Samuel; Bancroft, Ben; Greenwood, Jake

2014-01-01

An experiment was carried out to investigate the changes in ionizing cosmic radiation as a function of altitude. This was carried out using a Geiger-Müller tube on-board a high altitude balloon, which rose to an altitude of 31 685 m. The gathered data show that the Geiger-Müller tube count readings increased to a maximum at an altitude of about 24…

Effects of Altitude on Turbojet Engine Performance

NASA Technical Reports Server (NTRS)

Fleming, William A

1951-01-01

Component and over-all performance characteristics of several turbojet engines investigated in the altitude facilities of the NACA Lewis Laboratory during the last several years are summarized to indicate the effects of altitude on turbojet engine performance. Data presented show that failure of turbojet engine performance to generalize for all altitudes can be traced to reductions in compressor efficiency, corrected air flow, and combustion efficiency at altitude. In addition, it is shown that although engines of different design may have equal thrusts at sea level, the thrusts at altitude may vary widely because of differences in compressor performance characteristics from one engine to another.

Space Operations Center orbit altitude selection strategy

NASA Technical Reports Server (NTRS)

Indrikis, J.; Myers, H. L.

1982-01-01

The strategy for the operational altitude selection has to respond to the Space Operation Center's (SOC) maintenance requirements and the logistics demands of the missions to be supported by the SOC. Three orbit strategies are developed: two are constant altitude, and one variable altitude. In order to minimize the effect of atmospheric uncertainty the dynamic altitude method is recommended. In this approach the SOC will operate at the optimum altitude for the prevailing atmospheric conditions and logistics model, provided that mission safety constraints are not violated. Over a typical solar activity cycle this method produces significant savings in the overall logistics cost.

Aerodynamics of heat exchangers for high-altitude aircraft

NASA Technical Reports Server (NTRS)

Drela, Mark

1996-01-01

Reduction of convective beat transfer with altitude dictates unusually large beat exchangers for piston- engined high-altitude aircraft The relatively large aircraft drag fraction associated with cooling at high altitudes makes the efficient design of the entire heat exchanger installation an essential part of the aircraft's aerodynamic design. The parameters that directly influence cooling drag are developed in the context of high-altitude flight Candidate wing airfoils that incorporate heat exchangers are examined. Such integrated wing-airfoil/heat-exchanger installations appear to be attractive alternatives to isolated heat.exchanger installations. Examples are drawn from integrated installations on existing or planned high-altitude aircraft.

[High altitude related health problems in travel medicine].

PubMed

Neumayr, Andreas

2013-06-01

Giving travel advice to travellers visiting high-altitude destinations around the globe is daily routine in travel clinics. However, with the classical focus on vaccinations, traveller's diarrhoea, mosquito protection and malaria prophylaxis, altitude-related health problems are often neglected at counselling. The importance to communicate these problems when giving travel advice is impressively reflected by the high prevalence of altitude-related health problems among tourists visiting high-lying tourist destinations. This article aims at providing an overview of core aspects of acclimatization to altitude and prevention of altitude-related health problems and to exemplarily address practice-oriented problem destinations.

High altitude pulmonary oedema (HAPE) in an Indian pilgrim.

PubMed

Panthi, Sagar; Basnyat, Buddha

2013-11-01

Increasing number of Hindu pilgrims visit the Himalayas where some of them suffer from high altitude illness including the life threatening forms, high altitude pulmonary oedema (HAPE) and high altitude cerebral oedema. Compared to tourists and trekkers, pilgrims are usually ignorant about altitude illness. This is a case of a pilgrim who suffered from HAPE on his trip to Kailash-Mansarovar and is brought to a tertiary level hospital in Kathmandu. This report emphasises on how to treat a patient with HAPE, a disease which is increasingly being seen in the high altitude pilgrim population.

High-Altitude-Induced alterations in Gut-Immune Axis: A review.

PubMed

Khanna, Kunjan; Mishra, K P; Ganju, Lilly; Kumar, Bhuvnesh; Singh, Shashi Bala

2018-03-04

High-altitude sojourn above 8000 ft is increasing day by day either for pilgrimage, mountaineering, holidaying or for strategic reasons. In India, soldiers are deployed to these high mountains for their duty or pilgrims visit to the holy places, which are located at very high altitude. A large population also resides permanently in high altitude regions. Every year thousands of pilgrims visit Holy cave of Shri Amarnath ji, which is above 15 000 ft. The poor acclimatization to high altitude may cause alteration in immunity. The low oxygen partial pressure may cause alterations in gut microbiota, which may cause changes in gut immunity. Effect of high altitude on gut-associated mucosal system is new area of research. Many studies have been carried out to understand the physiology and immunology behind the high-altitude-induced gut problems. Few interventions have also been discovered to circumvent the problems caused due to high-altitude conditions. In this review, we have discussed the effects of high-altitude-induced changes in gut immunity particularly peyer's patches, NK cells and inflammatory cytokines, secretary immunoglobulins and gut microbiota. The published articles from PubMed and Google scholar from year 1975 to 2017 on high-altitude hypoxia and gut immunity are cited in this review.

High altitude gust acceleration environment as experienced by a supersonic airplane

NASA Technical Reports Server (NTRS)

Ehernberger, L. J.; Love, B. J.

1975-01-01

High altitude turbulence experienced at supersonic speeds is described in terms of gust accelerations measured on the YF-12A airplane. The data were obtained during 90 flights at altitudes above 12.2 kilometers (40,000 feet). Subjective turbulence intensity ratings were obtained from air crew members. The air crew often rated given gust accelerations as being more intense during high altitude supersonic flight than during low altitude subsonic flight. The portion of flight distance in turbulence ranged from 6 percent to 8 percent at altitudes between 12.2 kilometers and 16.8 kilometers (40,000 feet and 55,000 feet) to less than 1 percent at altitudes above 18.3 kilometers (60,000 feet). The amount of turbulence varied with season, increasing by a factor of 3 or more from summer to winter. Given values of gust acceleration were less frequent, on the basis of distance traveled, for supersonic flight of the YF-12A airplane at altitudes above 12.2 kilometers (40,000 feet) than for subsonic flight of a jet passenger airplane at altitudes below 12.2 kilometers (40,000 feet). The median thickness of high altitude turbulence patches was less than 400 meters (1300 feet); the median length was less than 16 kilometers (10 miles). The distribution of the patch dimensions tended to be log normal.

Erythropoietin, 2,3 DPG, oxygen transport capacity, and altitude training in adolescent Alpine skiers.

PubMed

Son, Hee Jeong; Kim, Hyo Jeong; Kim, Jin Hae; Ohno, Hideki; Kim, Chang Keun

2012-01-01

Rapid growth during adolescence caused by metabolic changes and their metabolic response to anaerobic and aerobic exercise differs considerably from that in adults and this is especially true in the responses to stresses, such as altitude exposure. However, there is little information on the suitability of exercise training at altitude for young athletes. Six male Korean adolescent alpine skiers (13-17 yr), with a skiing career of 3-5 yr, participated in the study. All subjects were exposed to an altitude of 2700 m (8858 ft) for 5 wk and altitude exposure consisted of 6 d/wk of training (4-5 h/d), with living quarters at 2100 m (-6890 ft) (Tignes, France). The 5 wk of ski training at altitude were maintained at the same level (the same number of slalom and giant slalom skiing trials) as at sea level. There was a significant increase in oxygen transport capacity, despite decreased erythropoietin (EPO) production (-31%) after altitude training. Red blood cell (RBC), hemoglobin (Hb), hematocrit (Hct), and 2,3 DPG concentrations increased significantly during altitude exposure and after return to sea level. Results indicate that applying altitude training in adolescent skiers may improve their endurance performance. However, EPO production during altitude training needs to be evaluated in larger future studies.

Genetic structure and isolation by altitude in rice landraces of Yunnan, China revealed by nucleotide and microsatellite marker polymorphisms

PubMed Central

A, Xinxiang; Yu, Tengqiong; Ma, Xiaoding; Zhang, Enlai; Wang, Yanjie; Cao, Guilan; Xu, Furong; Dai, Luyuan; Han, Longzhi

2017-01-01

Rice landraces, a genetic reservoir for varietal improvement, are developed by farmers through artificial selection during the long-term domestication process. To efficiently conserve, manage, and use such germplasm resources, an understanding of the genetic structure and differentiation of local rice landraces is required. In this study, we analyzed 188 accessions of rice landraces collected from localities across an altitudinal gradient from 425 to 2, 274 m above sea level in Yunnan Province, China using ten target genes and 48 SSR markers. We detected clear differentiation of the rice landraces into indica and japonica groups and further separation of the accessions in each group into two subgroups according to altitude, including a lower altitude subgroup and higher altitude subgroup. The AMOVA results showed significant genetic differentiation among altitude zones at SSRs and most genes, except Os1977 and STS22. We further determined that differentiation among landrace populations followed a model of isolation by altitude, in which gene flow was higher among populations at similar altitude levels than across different altitude levels. Our findings demonstrated that both adaptation to altitude and altitude-dependent gene flow played key roles in the genetic differentiation of rice landraces in Yunnan, China. PMID:28423046

Genetic structure and isolation by altitude in rice landraces of Yunnan, China revealed by nucleotide and microsatellite marker polymorphisms.

PubMed

Cui, Di; Tang, Cuifeng; Li, Jinmei; A, Xinxiang; Yu, Tengqiong; Ma, Xiaoding; Zhang, Enlai; Wang, Yanjie; Cao, Guilan; Xu, Furong; Dai, Luyuan; Han, Longzhi; Koh, Hee-Jong

2017-01-01

Rice landraces, a genetic reservoir for varietal improvement, are developed by farmers through artificial selection during the long-term domestication process. To efficiently conserve, manage, and use such germplasm resources, an understanding of the genetic structure and differentiation of local rice landraces is required. In this study, we analyzed 188 accessions of rice landraces collected from localities across an altitudinal gradient from 425 to 2, 274 m above sea level in Yunnan Province, China using ten target genes and 48 SSR markers. We detected clear differentiation of the rice landraces into indica and japonica groups and further separation of the accessions in each group into two subgroups according to altitude, including a lower altitude subgroup and higher altitude subgroup. The AMOVA results showed significant genetic differentiation among altitude zones at SSRs and most genes, except Os1977 and STS22. We further determined that differentiation among landrace populations followed a model of isolation by altitude, in which gene flow was higher among populations at similar altitude levels than across different altitude levels. Our findings demonstrated that both adaptation to altitude and altitude-dependent gene flow played key roles in the genetic differentiation of rice landraces in Yunnan, China.

Altitude exposures during commercial flight: a reappraisal.

PubMed

Hampson, Neil B; Kregenow, David A; Mahoney, Anne M; Kirtland, Steven H; Horan, Kathleen L; Holm, James R; Gerbino, Anthony J

2013-01-01

Hypobaric hypoxia during commercial air travel has the potential to cause or worsen hypoxemia in individuals with pre-existing cardiopulmonary compromise. Knowledge of cabin altitude pressures aboard contemporary flights is essential to counseling patients accurately about flying safety. The objective of the study was to measure peak cabin altitudes during U.S. domestic commercial flights on a variety of aircraft. A handheld mountaineering altimeter was carried by the investigators in the plane cabin during commercial air travel and peak cabin altitude measured. The values were then compared between aircraft models, aircraft classes, and distances flown. The average peak cabin altitude on 207 flights aboard 17 different aircraft was 6341 +/- 1813 ft (1933 m +/- 553 m), significantly higher than when measured in a similar fashion in 1988. Peak cabin altitude was significantly higher for flights longer than 750 mi (7085 +/- 801 ft) compared to shorter flights (5160 +/- 2290 ft/1573 +/- 698 m). Cabin altitude increased linearly with flight distance for flights up to 750 mi in length, but was independent of flight distance for flights exceeding 750 mi. Peak cabin altitude was less than 5000 ft (1524 m) in 70% of flights shorter than 500 mi. Peak cabin altitudes greater than 8000 ft (2438 m) were measured on approximately 10% of the total flights. Peak cabin altitude on commercial aircraft flights has risen over time. Cabin altitude is lower with flights of shorter distance. Physicians should take these factors into account when determining an individual's need for supplemental oxygen during commercial air travel.

Relativistic electron flux comparisons at low and high altitudes with fast time resolution and broad spatial coverage

NASA Technical Reports Server (NTRS)

Imhof, W. L.; Gaines, E. E.; Mcglennon, J. P.; Baker, D. N.; Reeves, G. D.; Belian, R. D.

1994-01-01

Analyses are presented for the first high-time resolution multisatellite study of the spatial and temporal characteristics of a relativistic electron enhancement event with a rapid onset. Measurements of MeV electrons were made from two low-altitude polar orbiting satellites and three spacecraft at synchronous altitude. The electron fluxes observed by the low-altitude satellites include precipitating electrons in both the bounce and drift loss cones as well as electrons that are stably trapped, whereas the observations at geosynchronous altitude are dominated by the trapped population. The fluxes of greater than 1 MeV electrons at low-satellite altitude over a wide range of L shells tracked very well the fluxes greater than 0.93 MeV at synchronous altitude.

Patterns of Genetic Variation across Altitude in Three Plant Species of Semi-Dry Grasslands

PubMed Central

Hahn, Thomas; Kettle, Chris J.; Ghazoul, Jaboury; Frei, Esther R.; Matter, Philippe; Pluess, Andrea R.

2012-01-01

Background Environmental gradients caused by altitudinal gradients may affect genetic variation within and among plant populations and inbreeding within populations. Populations in the upper range periphery of a species may be important source populations for range shifts to higher altitude in response to climate change. In this study we investigate patterns of population genetic variation at upper peripheral and lower more central altitudes in three common plant species of semi-dry grasslands in montane landscapes. Methodology/Principal Findings In Briza media, Trifolium montanum and Ranunculus bulbosus genetic diversity, inbreeding and genetic relatedness of individuals within populations and genetic differentiation among populations was characterized using AFLP markers. Populations were sampled in the Swiss Alps at 1800 (upper periphery of the study organisms) and at 1200 m a.s.l. Genetic diversity was not affected by altitude and only in B. media inbreeding was greater at higher altitudes. Genetic differentiation was slightly greater among populations at higher altitudes in B. media and individuals within populations were more related to each other compared to individuals in lower altitude populations. A similar but less strong pattern of differentiation and relatedness was observed in T. montanum, while in R. bulbosus there was no effect of altitude. Estimations of population size and isolation of populations were similar, both at higher and lower altitudes. Conclusions/Significance Our results suggest that altitude does not affect genetic diversity in the grassland species under study. Genetic differentiation of populations increased only slightly at higher elevation, probably due to extensive (historic) gene flow among altitudes. Potentially pre-adapted genes might therefore spread easily across altitudes. Our study indicates that populations at the upper periphery are not genetically depauperate or isolated and thus may be important source populations for migration under climate change. PMID:22870236

Impact of extreme exercise at high altitude on oxidative stress in humans.

PubMed

Quindry, John; Dumke, Charles; Slivka, Dustin; Ruby, Brent

2016-09-15

Exercise and oxidative stress research continues to grow as a physiological subdiscipline. The influence of high altitude on exercise and oxidative stress is among the recent topics of intense study in this area. Early findings indicate that exercise at high altitude has an independent influence on free radical generation and the resultant oxidative stress. This review provides a detailed summary of oxidative stress biochemistry as gleaned mainly from studies of humans exercising at high altitude. Understanding of the human response to exercise at altitude is largely derived from field-based research at altitudes above 3000 m in addition to laboratory studies which employ normobaric hypoxia. The implications of oxidative stress incurred during high altitude exercise appear to be a transient increase in oxidative damage followed by redox-sensitive adaptations in multiple tissues. These outcomes are consistent for lowland natives, high altitude acclimated sojourners and highland natives, although the latter group exhibits a more robust adaptive response. To date there is no evidence that altitude-induced oxidative stress is deleterious to normal training or recovery scenarios. Limited evidence suggests that deleterious outcomes related to oxidative stress are limited to instances where individuals are exposed to extreme elevations for extended durations. However, confirmation of this tentative conclusion requires further investigation. More applicably, altitude-induced hypoxia may have an independent influence on redox-sensitive adaptive responses to exercise and exercise recovery. If correct, these findings may hold important implications for athletes, mountaineers, and soldiers working at high altitude. These points are raised within the confines of published research on the topic of oxidative stress during exercise at altitude. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

Ventilation during simulated altitude, normobaric hypoxia and normoxic hypobaria

NASA Technical Reports Server (NTRS)

Loeppky, J. A.; Icenogle, M.; Scotto, P.; Robergs, R.; Hinghofer-Szalkay, H.; Roach, R. C.; Leoppky, J. A. (Principal Investigator)

1997-01-01

To investigate the possible effect of hypobaria on ventilation (VE) at high altitude, we exposed nine men to three conditions for 10 h in a chamber on separate occasions at least 1 week apart. These three conditions were: altitude (PB = 432, FIO2 = 0.207), normobaric hypoxia (PB = 614, FIO2 = 0.142) and normoxic hypobaria (PB = 434, FIO2 = 0.296). In addition, post-test measurements were made 2 h after returning to ambient conditions at normobaric normoxia (PB = 636, FIO2 = 0.204). In the first hour of exposure VE was increased similarly by altitude and normobaric hypoxia. The was 38% above post-test values and end-tidal CO2 (PET(CO2) was lower by 4 mmHg. After 3, 6 and 9 h, the average VE in normobaric hypoxia was 26% higher than at altitude (p < 0.01), resulting primarily from a decline in VE at altitude. The difference between altitude and normobaric hypoxia was greatest at 3 h (+ 39%). In spite of the higher VE during normobaric hypoxia, the PET(CO2) was higher than at altitude. Changes in VE and PET(CO2) in normoxic hypobaria were minimal relative to normobaric normoxia post-test measurements. One possible explanation for the lower VE at altitude is that CO2 elimination is relatively less at altitude because of a reduction in inspired gas density compared to normobaric hypoxia; this may reduce the work of breathing or alveolar deadspace. The greater VE during the first hour at altitude, relative to subsequent measurements, may be related to the appearance of microbubbles in the pulmonary circulation acting to transiently worsen matching. Results indicate that hypobaria per se effects ventilation under altitude conditions.

High altitude is an independent risk factor for venous thromboembolism following arthroscopic rotator cuff repair: a matched case-control study in Medicare patients.

PubMed

Cancienne, Jourdan M; Burrus, M Tyrrell; Diduch, David R; Werner, Brian C

2017-01-01

Although the risk of venous thromboembolism (VTE) following elective shoulder arthroscopy is low, the large volume of procedures performed each year yields a significant annual burden of patients with thromboembolic complications. The purpose of this study was to evaluate the association of high procedural altitude with the incidence of postoperative VTE following arthroscopic rotator cuff repair. A Medicare database was queried for all patients undergoing arthroscopic rotator cuff repair from 2005 to 2012. All patients with procedures performed at an altitude of 4000 feet or higher were grouped into the "high-altitude" study cohort. Patients with procedures performed at an altitude of 100 feet or lower were then matched to patients in the high-altitude cohort on the basis of age, gender, and medical comorbidities. The rate of VTE was then assessed for both the high-altitude and matched low-altitude cohorts within 90 days postoperatively. The rates of combined VTE (odds ratio [OR], 2.6; P < .0001), pulmonary embolism (OR, 4.3; P < .0001), and lower extremity deep venous thrombosis within 90 days (OR, 2.2; P = .029) were all significantly higher in patients with procedures performed at high altitude compared with matched patients with the same procedures performed at low altitude. Procedural altitude >4000 feet is associated with significantly increased rates of postoperative VTE, including deep venous thrombosis and pulmonary embolism, compared with age-, gender-, and comorbidity-matched patients undergoing the same procedures at altitudes <100 feet. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Associations Between Arterial Oxygen Saturation, Body Size and Limb Measurements Among High-Altitude Andean Children

PubMed Central

Pomeroy, Emma; Stock, Jay T; Stanojevic, Sanja; Miranda, J Jaime; Cole, Tim J; Wells, Jonathan CK

2013-01-01

Objectives The relative influences of hypoxia and other environmental stressors on growth at altitude remain unclear. Previous work demonstrated an association between peripheral arterial oxygen saturation (SpO2) and anthropometry (especially tibia length) among Tibetan and Han children at altitude. We investigated whether similar associations exist among Andeans, and the patterning of associations between SpO2 and anthropometry. Methods Stature, head-trunk height, total upper and lower limb lengths, zeugopod (ulna and tibia) and autopod (hand and foot) lengths were measured in Peruvian children (0.5–14 years) living at >3000 m altitude. SpO2 was measured by pulse oximetry. Anthropometry was converted to internal z scores. Correlation and multiple regression were used to examine associations between anthropometry z scores and SpO2, altitude, or SpO2 adjusted for altitude since altitude is a major determinant of variation in SpO2. Results SpO2 and altitude show weak, significant correlations with zeugopod length z scores and still weaker significant correlations with total upper and lower limb length z scores. Correlations with z scores for stature, head-trunk height, or autopod lengths are not significant. Adjusted for altitude, there is no significant association between anthropometry and SpO2. Conclusions Associations between SpO2 or altitude and total limb and zeugopod length z scores exist among Andean children. However, the relationships are relatively weak, and while the relationship between anthropometry and altitude may be partly mediated by SpO2, other factors that covary with altitude (e.g., socioeconomic status, health) are likely to influence anthropometry. The results support suggestions that zeugopod lengths are particularly sensitive to environmental stressors. Am. J. Hum. Biol., 25:629–636, 2013. © 2013 Wiley Periodicals, Inc. PMID:23904412

Altitude characteristics of selected air quality analyzers

NASA Technical Reports Server (NTRS)

White, J. H.; Strong, R.; Tommerdahl, J. B.

1979-01-01

The effects of altitude (pressure) on the operation and sensitivity of various air quality analyzers frequently flown on aircraft were analyzed. Two ozone analyzers were studied at altitudes from 600 to 7500 m and a nitrogen oxides chemiluminescence detector and a sulfur dioxide flame photometric detector were studied at altitudes from 600 to 3000 m. Calibration curves for altitude corrections to the sensitivity of the instruments are presented along with discussion of observed instrument behavior.

Altitude training considerations for the winter sport athlete.

PubMed

Chapman, Robert F; Stickford, Jonathon L; Levine, Benjamin D

2010-03-01

Winter sports events routinely take place at low to moderate altitudes, and nearly all Winter Olympic Games have had at least one venue at an altitude >1000 m. The acute and chronic effects of altitude can have a substantial effect on performance outcomes. Acutely, the decline in oxygen delivery to working muscle decreases maximal oxygen uptake, negatively affecting performance in endurance events, such as cross-country skiing and biathlon. The reduction in air resistance at altitude can dramatically affect sports involving high velocities and technical skill components, such as ski jumping, speed skating, figure skating and ice hockey. Dissociation between velocity and sensations usually associated with work intensity (ventilation, metabolic signals in skeletal muscle and heart rate) may impair pacing strategy and make it difficult to determine optimal race pace. For competitions taking place at altitude, a number of strategies may be useful, depending on the altitude of residence of the athlete and ultimate competition altitude, as follows. First, allow extra time and practice (how much is yet undetermined) for athletes to adjust to the changes in projectile motion; hockey, shooting, figure skating and ski jumping may be particularly affected. These considerations apply equally in the reverse direction; that is, for athletes practising at altitude but competing at sea level. Second, allow time for acclimatization for endurance sports: 3-5 days if possible, especially for low altitude (500-2000 m); 1-2 weeks for moderate altitude (2000-3000 m); and at least 2 weeks if possible for high altitude (>3000 m). Third, increase exercise-recovery ratios as much as possible, with 1:3 ratio probably optimal, and consider more frequent substitutions for sports where this is allowed, such as ice hockey. Fourth, consider the use of supplemental O(2) on the sideline (ice hockey) or in between heats (skating and Alpine skiing) to facilitate recovery. For competitions at sea level, the 'live high-train low' model of altitude training can help athletes in endurance events to maximize performance.

Determinants of erythropoietin release in response to short-term hypobaric hypoxia

NASA Technical Reports Server (NTRS)

Ge, Ri-Li; Witkowski, S.; Zhang, Y.; Alfrey, C.; Sivieri, M.; Karlsen, T.; Resaland, G. K.; Harber, M.; Stray-Gundersen, J.; Levine, B. D.

2002-01-01

We measured blood erythropoietin (EPO) concentration, arterial O(2) saturation (Sa(O(2))), and urine PO(2) in 48 subjects (32 men and 16 women) at sea level and after 6 and 24 h at simulated altitudes of 1,780, 2,085, 2,454, and 2,800 m. Renal blood flow (Doppler) and Hb were determined at sea level and after 6 h at each altitude (n = 24) to calculate renal O(2) delivery. EPO increased significantly after 6 h at all altitudes and continued to increase after 24 h at 2,454 and 2,800 m, although not at 1,780 or 2,085 m. The increase in EPO varied markedly among individuals, ranging from -41 to 400% after 24 h at 2,800 m. Similar to EPO, urine PO(2) decreased after 6 h at all altitudes and returned to baseline by 24 h at the two lowest altitudes but remained decreased at the two highest altitudes. Urine PO(2) was closely related to EPO via a curvilinear relationship (r(2) = 0.99), although also with prominent individual variability. Renal blood flow remained unchanged at all altitudes. Sa(O(2)) decreased slightly after 6 h at the lowest altitudes but decreased more prominently at the highest altitudes. There were only modest, albeit statistically significant, relationships between EPO and Sa(O(2)) (r = 0.41, P < 0.05) and no significant relationship with renal O(2) delivery. These data suggest that 1) the altitude-induced increase in EPO is "dose" dependent: altitudes > or =2,100-2,500 m appear to be a threshold for stimulating sustained EPO release in most subjects; 2) short-term acclimatization may restore renal tissue oxygenation and restrain the rise in EPO at the lowest altitudes; and 3) there is marked individual variability in the erythropoietic response to altitude that is only partially explained by "upstream" physiological factors such as those reflecting O(2) delivery to EPO-producing tissues.

High Altitude Launch for a Practical SSTO

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.; Denis, Vincent; Lyons, Valerie (Technical Monitor)

2003-01-01

Existing engineering materials allow the construction of towers to heights of many kilometers. Orbital launch from a high altitude has significant advantages over sea-level launch due to the reduced atmospheric pressure, resulting in lower atmospheric drag on the vehicle and allowing higher rocket engine performance. High-altitude launch sites are particularly advantageous for single-stage to orbit (SSTO) vehicles, where the payload is typically 2% of the initial launch mass. An earlier paper enumerated some of the advantages of high altitude launch of SSTO vehicles. In this paper, we calculate launch trajectories for a candidate SSTO vehicle, and calculate the advantage of launch at launch altitudes 5 to 25 kilometer altitudes above sea level. The performance increase can be directly translated into increased payload capability to orbit, ranging from 5 to 20% increase in the mass to orbit. For a candidate vehicle with an initial payload fraction of 2% of gross lift-off weight, this corresponds to 31% increase in payload (for 5-km launch altitude) to 122% additional payload (for 25-km launch altitude).

High Altitude Launch for a Practical SSTO

NASA Astrophysics Data System (ADS)

Landis, Geoffrey A.; Denis, Vincent

2003-01-01

Existing engineering materials allow the constuction of towers to heights of many kilometers. Orbital launch from a high altitude has significant advantages over sea-level launch due to the reduced atmospheric pressure, resulting in lower atmospheric drag on the vehicle and allowing higher rocket engine performance. High-altitude launch sites are particularly advantageous for single-stage to orbit (SSTO) vehicles, where the payload is typically 2% of the initial launch mass. An earlier paper enumerated some of the advantages of high altitude launch of SSTO vehicles. In this paper, we calculate launch trajectories for a candidate SSTO vehicle, and calculate the advantage of launch at launch altitudes 5 to 25 kilometer altitudes above sea level. The performance increase can be directly translated into increased payload capability to orbit, ranging from 5 to 20% increase in the mass to orbit. For a candidate vehicle with an initial payload fraction of 2% of gross lift-off weight, this corresponds to 31% increase in payload (for 5-km launch altitude) to 122% additional payload (for 25-km launch altitude).

The Effect of Residing Altitude on Levels of High-Density Lipoprotein Cholesterol: A Pilot Study From the Omani Arab Population.

PubMed

Al Riyami, Nafila B; Banerjee, Yajnavalka; Al-Waili, Khalid; Rizvi, Syed G; Al-Yahyaee, Said; Hassan, Mohammed O; Albarwani, Sulayma; Al-Rasadi, Khalid; Bayoumi, Riad A

2015-07-01

Lower mortality rates from coronary heart disease and higher levels of serum high-density lipoprotein cholesterol (HDL-C) have been observed in populations residing at high altitude. However, this effect has not been investigated in Arab populations, which exhibit considerable genetic homogeneity. We assessed the relationship between residing altitude and HDL-C in 2 genetically similar Omani Arab populations residing at different altitudes. The association between the levels of HDL-C and other metabolic parameters was also investigated. The levels of HDL-C were significantly higher in the high-altitude group compared with the low-altitude group. Stepwise regression analysis showed that altitude was the most significant factor affecting HDL-C, followed by gender, serum triglycerides, and finally the 2-hour postprandial plasma glucose. This finding is consistent with previously published studies from other populations and should be taken into consideration when comparing cardiovascular risk factors in populations residing at different altitudes. © The Author(s) 2014.

Human llamas: adaptation to altitude in subjects with high hemoglobin oxygen affinity.

PubMed Central

Hebbel, R P; Eaton, J W; Kronenberg, R S; Zanjani, E D; Moore, L G; Berger, E M

1978-01-01

To assess the adaptive value of the right-shift of the oxyhemoglobin dissociation curve (decreased affinity for oxygen) observed in humans upon altitude exposure, the short-term physiologic responses to altitude-induced hypoxia were evaluated in two subjects with a high oxygen affinity hemoglobin (Hb Andrew-Minneapolis) and in two of their normal siblings. In striking contrast to normal subjects, at moderately high altitude (3,100 m) the high affinity subjects manifested: (a) lesser increments in resting heart rate; (b) minimal increases in plasma and urinary erythropoietin; (c) no decrement in maximal oxygen consumption; and (d) no thrombocytopenia. There was no difference between subject pairs in 2,3-diphosphoglycerate response to altitude exposure. These results tend to contradict the belief that a decrease in hemoglobin oxygen affinity is of adaptive value to humans at moderate altitudes. Rather, they support the hypothesis that, despite disadvantages at low altitude, a left-shifted oxyhemoglobin dissociation curve may confer a degree of preadaptation to altitude. PMID:29054

Glucose Homeostasis During Short-term and Prolonged Exposure to High Altitudes

PubMed Central

Ader, Marilyn; Bergman, Richard N.

2015-01-01

Most of the literature related to high altitude medicine is devoted to the short-term effects of high-altitude exposure on human physiology. However, long-term effects of living at high altitudes may be more important in relation to human disease because more than 400 million people worldwide reside above 1500 m. Interestingly, individuals living at higher altitudes have a lower fasting glycemia and better glucose tolerance compared with those who live near sea level. There is also emerging evidence of the lower prevalence of both obesity and diabetes at higher altitudes. The mechanisms underlying improved glucose control at higher altitudes remain unclear. In this review, we present the most current evidence about glucose homeostasis in residents living above 1500 m and discuss possible mechanisms that could explain the lower fasting glycemia and lower prevalence of obesity and diabetes in this population. Understanding the mechanisms that regulate and maintain the lower fasting glycemia in individuals who live at higher altitudes could lead to new therapeutics for impaired glucose homeostasis. PMID:25675133

Acclimatization and tolerance to extreme altitude

NASA Technical Reports Server (NTRS)

West, J. B.

1993-01-01

During the last ten years, two major experiments have elucidated the factors determining acclimatization and tolerance to extreme altitude (over 7000 m). These were the American Medical Research Expedition to Everest, and the low pressure chamber simulation, Operation Everest II. Extreme hyperventilation is one of the most important responses to extreme altitude. Its chief value is that it allows the climber to maintain an alveolar PO2 which keeps the arterial PO2 above dangerously low levels. Even so, there is evidence of residual impairment of central nervous system function after ascents to extreme altitude, and maximal oxygen consumption falls precipitously above 7000 m. The term 'acclimatization' is probably not appropriate for altitudes above 8000 m, because the body steadily deteriorates at these altitudes. Tolerance to extreme altitude is critically dependent on barometric pressure, and even seasonal changes in pressure probably affect climbing performance near the summit of Mt Everest. Supplementary oxygen always improves exercise tolerance at extreme altitudes, and rescue oxygen should be available on climbing expeditions to 8000 m peaks.

Preacclimatization in hypoxic chambers for high altitude sojourns.

PubMed

Küpper, Thomas E A H; Schöffl, Volker

2010-09-01

Since hypoxic chambers are more and more available, they are used for preacclimatization to prepare for sojourns at high altitude. Since there are different protocols and the data differ, there is no general consensus about the standard how to perform preacclimatization by simulated altitude. The paper reviews the different types of exposure and focuses on the target groups which may benefit from preacclimatization. Since data about intermittent hypoxia for some hours per day to reduce the incidence of acute mountain sickness differ, it is suggested to perform preacclimatization by sleeping some nights at a simulated altitude which follows the altitude profile of the "gold standard" for high altitude acclimatization.

Altitude-related cough

PubMed Central

2013-01-01

Altitude-related cough is a troublesome condition of uncertain aetiology that affects many visitors to high altitude. The traditionally held belief that it was due solely to the inspiration of cold, dry air was refuted by observations and experiments in long duration hypobaric chamber studies. It is likely that altitude-related cough is a symptom of a number of possible perturbations in the cough reflex arc that may exist independently or together. These include loss of water from the respiratory tract; respiratory tract infections and sub-clinical high altitude pulmonary oedema. The published work on altitude-related cough is reviewed and possible aetiologies for the condition are discussed. PMID:24175933

Stratospheric turbulence measurements and models for aerospace plane design

NASA Technical Reports Server (NTRS)

Ehernberger, L. J.

1992-01-01

Progress in computational atmospheric dynamics is exhibiting the ability of numerical simulation to describe instability processes associated with turbulence observed at altitudes between 15 and 25 km in the lower stratosphere. As these numerical simulation tools mature, they can be used to extend estimates of atmospheric perturbations from the present gust database for airplane design at altitudes below 15 km to altitudes between 25 and 50 km where aerospace plane operation would be at hypersonic speeds. The amount of available gust data and number of temperature perturbation observations are limited at altitudes between 15 and 25 km. On the other hand, in-situ gust data at higher altitudes are virtually nonexistent. The uncertain potential for future airbreathing hypersonic flight research vehicles to encounter strong turbulence at higher altitudes could penalize the design of these vehicles by undue cost or limitations on performance. Because the atmospheric structure changes markedly with altitude, direct extrapolation of gust magnitudes and encounter probabilities to the higher flight altitudes is not advisable. This paper presents a brief review of turbulence characteristics observed in the lower stratosphere and highlights the progress of computational atmospheric dynamics that may be used to estimate the severity of atmospheric transients at higher altitudes.

Piloted simulation study of a balloon-assisted deployment of an aircraft at high altitude

NASA Technical Reports Server (NTRS)

Murray, James; Moes, Timothy; Norlin, Ken; Bauer, Jeffrey; Geenen, Robert; Moulton, Bryan; Hoang, Stephen

1992-01-01

A piloted simulation was used to study the feasibility of a balloon assisted deployment of a research aircraft at high altitude. In the simulation study, an unmanned, modified sailplane was carried to 110,000 ft with a high altitude balloon and released in a nose down attitude. A remote pilot controlled the aircraft through a pullout and then executed a zoom climb to a trimmed, 1 g flight condition. A small parachute was used to limit the Mach number during the pullout to avoid adverse transonic effects. The use of small rocket motor was studied for increasing the maximum attainable altitude. Aerodynamic modifications to the basic sailplane included applying supercritical airfoil gloves over the existing wing and tail surfaces. The aerodynamic model of the simulated aircraft was based on low Reynolds number wind tunnel tests and computational techniques, and included large Mach number and Reynolds number effects at high altitude. Parametric variations were performed to study the effects of launch altitude, gross weight, Mach number limit, and parachute size on the maximum attainable stabilized altitude. A test altitude of approx. 95,000 ft was attained, and altitudes in excess of 100,000 ft was attained.

Behavioural and physiological adaptations to low-temperature environments in the common frog, Rana temporaria.

PubMed

Muir, Anna P; Biek, Roman; Mable, Barbara K

2014-05-23

Extreme environments can impose strong ecological and evolutionary pressures at a local level. Ectotherms are particularly sensitive to low-temperature environments, which can result in a reduced activity period, slowed physiological processes and increased exposure to sub-zero temperatures. The aim of this study was to assess the behavioural and physiological responses that facilitate survival in low-temperature environments. In particular, we asked: 1) do high-altitude common frog (Rana temporaria) adults extend the time available for larval growth by breeding at lower temperatures than low-altitude individuals?; and 2) do tadpoles sampled from high-altitude sites differ physiologically from those from low-altitude sites, in terms of routine metabolic rate (RMR) and freeze tolerance? Breeding date was assessed as the first day of spawn observation and local temperature recorded for five, paired high- and low-altitude R. temporaria breeding sites in Scotland. Spawn was collected and tadpoles raised in a common laboratory environment, where RMR was measured as oxygen consumed using a closed respiratory tube system. Freeze tolerance was measured as survival following slow cooling to the point when all container water had frozen. We found that breeding did not occur below 5°C at any site and there was no significant relationship between breeding temperature and altitude, leading to a delay in spawning of five days for every 100 m increase in altitude. The relationship between altitude and RMR varied by mountain but was lower for individuals sampled from high- than low-altitude sites within the three mountains with the highest high-altitude sites (≥900 m). In contrast, individuals sampled from low-altitudes survived freezing significantly better than those from high-altitudes, across all mountains. Our results suggest that adults at high-altitude do not show behavioural adaptations in terms of breeding at lower temperatures. However, tadpoles appear to have the potential to adapt physiologically to surviving at high-altitude via reduced RMR but without an increase in freeze tolerance. Therefore, survival at high-altitude may be facilitated by physiological mechanisms that permit faster growth rates, allowing completion of larval development within a shorter time period, alleviating the need for adaptations that extend the time available for larval growth.

77 FR 38477 - IFR Altitudes; Miscellaneous Amendments

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-28

... CONSEQUENCES, NM VORTAC. Sec. 95.4000 High Altitude RNAV Routes Sec. 95.4130 RNAV Route Q130 is Amended to Read.... No. 501] IFR Altitudes; Miscellaneous Amendments AGENCY: Federal Aviation Administration (FAA), DOT... (instrument flight rules) altitudes and changeover points for certain Federal airways, jet routes, or direct...

14 CFR 27.1527 - Maximum operating altitude.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Maximum operating altitude. 27.1527 Section 27.1527 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... § 27.1527 Maximum operating altitude. The maximum altitude up to which operation is allowed, as limited...

14 CFR 29.1527 - Maximum operating altitude.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Maximum operating altitude. 29.1527 Section 29.1527 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Limitations § 29.1527 Maximum operating altitude. The maximum altitude up to which operation is allowed, as...

Preliminary Altitude Performance Data of J71-A2 Turbojet Engine Afterburner

NASA Technical Reports Server (NTRS)

Useller, James W.; Mallett, William E.

1954-01-01

The performance and operational characteristics of the J71-A2 turbojet-engine afterburner were investigated for a range of altitudes from 23,000 to 60,000 feet at a flight Mach number of 0,9 and at flight Mach numbers of 0.6, 0.9, and 1.0 at an altitude of 45,000 feet. The combustion performance and altitude operational limits, as well as the altitude starting characteristics have been determined.

Sleep architecture changes during a trek from 1400 to 5000 m in the Nepal Himalaya.

PubMed

Johnson, Pamela L; Edwards, Natalie; Burgess, Keith R; Sullivan, Colin E

2010-03-01

The aim of this study was to examine sleep architecture at high altitude and its relationship to periodic breathing during incremental increases in altitude. Nineteen normal, sea level-dwelling volunteers were studied at sea level and five altitudes in the Nepal Himalaya. Morning arterial blood gases and overnight polysomnography were performed in 14 subjects at altitudes: 0, 1400, 3500, 3900, 4200 and 5000 m above sea level. Subjects became progressively more hypoxic, hypocapnic and alkalinic with increasing altitude. As expected, sleep architecture was affected by increasing altitude. While time spent in Stage 1 non-rapid eye movement sleep increased at 3500 m and higher (P < 0.001), time spent in slow-wave sleep (SWS) decreased as altitude increased. Time spent in rapid eye movement (REM) sleep was well preserved. In subjects who developed periodic breathing during sleep at one or more altitudes (16 of 19), arousals because of periodic breathing predominated, contributing to an increase in the total arousal index. However, there were no differences in sleep architecture or sleeping oxyhaemoglobin saturation between subjects who developed periodic breathing and those who did not. As altitude increased, sleep architecture became progressively more disturbed, with Stage 1 and SWS being affected from 3500 m, while REM sleep was well preserved. Periodic breathing was commonplace at all altitudes, and while associated with increases in arousal indices, did not have any apparent effect on sleep architecture.

[Co-occurrence of soil fauna communities with changes in altitude on the northern slope of Changbai Mountain].

PubMed

Tong, Fuchun; Jin, Zhedong; Wang, Qingli; Xiao, Yihua

2003-10-01

The co-occurrence of soil fauna communities at different altitudes may reflect at some extent the relationships among communities, their coexistence, and the replacement of species along the altitude gradient. The continuous or disjunctive distribution of different species along altitude gradient not only reflected the environment variation at altitude gradient, but also the biological and ecological spatiality as well as the adaptability of species. The northern slope of Changbai Moutain has not only a high diversity in soil fauna types and species, but also a high variation of diversity pattern along the altitude gradient, which is a perfect transect for the research of biodiversity and gradient patterns. From 550 m to 2,560 m on the northern slope of Changbai Mountain, twenty-two plots were investigated with an interval of 100 m in altitude. By using Jaccard index, the co-occurrence of soil fauna communities at different altitudes was analyzed. For the species of different life forms or for all the species as a whole, the co-occurrence of soil faunae between neighboring communities was the highest, except for that between different soil fauna types. The peak and valley values of the co-occurrence of soil fauna communities along altitude gradient were matched with their gradient patterns, and the co-occurrence of soil faunae at different layers or all of the soil fauna communities were decreased with increasing altitude difference.

Helicopter pilot estimation of self-altitude in a degraded visual environment

NASA Astrophysics Data System (ADS)

Crowley, John S.; Haworth, Loran A.; Szoboszlay, Zoltan P.; Lee, Alan G.

2000-06-01

The effect of night vision devices and degraded visual imagery on self-attitude perception is unknown. Thirteen Army aviators with normal vision flew five flights under various visual conditions in a modified AH-1 (Cobra) helicopter. Subjects estimated their altitude or flew to specified altitudes while flying a series of maneuvers. The results showed that subjects were better at detecting and controlling changes in altitude than they were at flying to or naming a specific altitude. In cruise flight and descent, the subjects tended to fly above the desired altitude, an error in the safe direction. While hovering, the direction of error was less predictable. In the low-level cruise flight scenario tested in this study, altitude perception was affected more by changes in image resolution than by changes in FOV or ocularity.

Diving at altitude: from definition to practice.

PubMed

Egi, S Murat; Pieri, Massimo; Marroni, Alessandro

2014-01-01

Diving above sea level has different motivations for recreational, military, commercial and scientific activities. Despite the apparently wide practice of inland diving, there are three major discrepancies about diving at altitude: threshold elevation that requires changes in sea level procedures; upper altitude limit of the applicability of these modifications; and independent validation of altitude adaptation methods of decompression algorithms. The first problem is solved by converting the normal fluctuation in barometric pressure to an altitude equivalent. Based on the barometric variations recorded from a meteorological center, it is possible to suggest 600 meters as a threshold for classifying a dive as an "altitude" dive. The second problem is solved by proposing the threshold altitude of aviation (2,400 meters) to classify "high" altitude dives. The DAN (Divers Alert Network) Europe diving database (DB) is analyzed to solve the third problem. The database consists of 65,050 dives collected from different dive computers. A total of 1,467 dives were found to be classified as altitude dives. However, by checking the elevation according to the logged geographical coordinates, 1,284 dives were disqualified because the altitude setting had been used as a conservative setting by the dive computer despite the fact that the dive was made at sea level. Furthermore, according to the description put forward in this manuscript, 72 dives were disqualified because the surface level elevation is lower than 600 meters. The number of field data (111 dives) is still very low to use for the validation of any particular method of altitude adaptation concerning decompression algorithms.

Effect of chronic perinatal hypoxia on the role of rho-kinase in pulmonary artery contraction in newborn lambs

PubMed Central

Terry, Michael H.; Merritt, Travis A.; Papamatheakis, Demosthenes G.; Blood, Quintin; Ross, Jonathon M.; Power, Gordon G.; Longo, Lawrence D.; Wilson, Sean M.

2013-01-01

Exposure to chronic hypoxia during gestation predisposes infants to neonatal pulmonary hypertension, but the underlying mechanisms remain unclear. Here, we test the hypothesis that moderate continuous hypoxia during gestation causes changes in the rho-kinase pathway that persist in the newborn period, altering vessel tone and responsiveness. Lambs kept at 3,801 m above sea level during gestation and the first 2 wk of life were compared with those with gestation at low altitude. In vitro studies of isolated pulmonary arterial rings found a more forceful contraction in response to KCl and 5-HT in high-altitude compared with low-altitude lambs. There was no difference between the effects of blockers of various pathways of extracellular Ca2+ entry in low- and high-altitude arteries. In contrast, inhibition of rho-kinase resulted in significantly greater attenuation of 5-HT constriction in high-altitude compared with low-altitude arteries. High-altitude lambs had higher baseline pulmonary artery pressures and greater elevations in pulmonary artery pressure during 15 min of acute hypoxia compared with low-altitude lambs. Despite evidence for an increased role for rho-kinase in high-altitude arteries, in vivo studies found no significant difference between the effects of rho-kinase inhibition on hypoxic pulmonary vasoconstriction in intact high-altitude and low-altitude lambs. We conclude that chronic hypoxia in utero results in increased vasopressor response to both acute hypoxia and serotonin, but that rho-kinase is involved only in the increased response to serotonin. PMID:23152110

Accuracy of Handheld Blood Glucose Meters at High Altitude

PubMed Central

de Vries, Suzanna T.; Fokkert, Marion J.; Dikkeschei, Bert D.; Rienks, Rienk; Bilo, Karin M.; Bilo, Henk J. G.

2010-01-01

Background Due to increasing numbers of people with diabetes taking part in extreme sports (e.g., high-altitude trekking), reliable handheld blood glucose meters (BGMs) are necessary. Accurate blood glucose measurement under extreme conditions is paramount for safe recreation at altitude. Prior studies reported bias in blood glucose measurements using different BGMs at high altitude. We hypothesized that glucose-oxidase based BGMs are more influenced by the lower atmospheric oxygen pressure at altitude than glucose dehydrogenase based BGMs. Methodology/Principal Findings Glucose measurements at simulated altitude of nine BGMs (six glucose dehydrogenase and three glucose oxidase BGMs) were compared to glucose measurement on a similar BGM at sea level and to a laboratory glucose reference method. Venous blood samples of four different glucose levels were used. Moreover, two glucose oxidase and two glucose dehydrogenase based BGMs were evaluated at different altitudes on Mount Kilimanjaro. Accuracy criteria were set at a bias <15% from reference glucose (when >6.5 mmol/L) and <1 mmol/L from reference glucose (when <6.5 mmol/L). No significant difference was observed between measurements at simulated altitude and sea level for either glucose oxidase based BGMs or glucose dehydrogenase based BGMs as a group phenomenon. Two GDH based BGMs did not meet set performance criteria. Most BGMs are generally overestimating true glucose concentration at high altitude. Conclusion At simulated high altitude all tested BGMs, including glucose oxidase based BGMs, did not show influence of low atmospheric oxygen pressure. All BGMs, except for two GDH based BGMs, performed within predefined criteria. At true high altitude one GDH based BGM had best precision and accuracy. PMID:21103399

40 CFR 610.34 - Special test conditions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... the device was installed. (b) High altitude. Devices for which specific claims of improved fuel economy at high altitude are made may be tested using the procedures in subpart D, at altitudes above 4000 feet. For other devices, testing at high altitude may be necessary for determining whether a device...

Detection of ocean color changes from high altitudes

NASA Technical Reports Server (NTRS)

Hovis, W. A.; Forman, M. L.; Blaine, L. R.

1973-01-01

The detection of ocean color changes, thought to be due to chlorophyll concentrations and gelbstoffe variations, is attempted from high altitude (11.3km) and low altitude (0.3km). The atmospheric back scattering is shown to reduce contrast, but not sufficiently to obscure color change detection at high altitudes.

A study of altitude-constrained supersonic cruise transport concepts

NASA Technical Reports Server (NTRS)

Tice, David C.; Martin, Glenn L.

1992-01-01

The effect of restricting maximum cruise altitude on the mission performance of two supersonic transport concepts across a selection of cruise Mach numbers is studied. Results indicate that a trapezoidal wing concept can be competitive with an arrow wing depending on the altitude and Mach number constraints imposed. The higher wing loading of trapezoidal wing configurations gives them an appreciably lower average cruise altitude than the lower wing loading of the arrow wing configurations, and this advantage increases as the maximum allowable cruise altitude is reduced.

Adaptation of aeronautical engines to high altitude flying

NASA Technical Reports Server (NTRS)

Kutzbach, K

1923-01-01

Issues and techniques relative to the adaptation of aircraft engines to high altitude flight are discussed. Covered here are the limits of engine output, modifications and characteristics of high altitude engines, the influence of air density on the proportions of fuel mixtures, methods of varying the proportions of fuel mixtures, the automatic prevention of fuel waste, and the design and application of air pressure regulators to high altitude flying. Summary: 1. Limits of engine output. 2. High altitude engines. 3. Influence of air density on proportions of mixture. 4. Methods of varying proportions of mixture. 5. Automatic prevention of fuel waste. 6. Design and application of air pressure regulators to high altitude flying.

Performance and Operational Characteristics of a Python Turbine-propeller Engine at Simulated Altitude Conditions / Carl L. Meyer and Lavern A. Johnson

NASA Technical Reports Server (NTRS)

Meyer, Carl L; Johnson, Lavern A

1952-01-01

The performance and operational characteristics of a Python turbine-propeller engine were investigated at simulated altitude conditions in the NACA Lewis altitude wind tunnel. In the performance phase, data were obtained over a range of engine speeds and exhaust nozzle areas at altitudes from 10,000 to 40,000 feet at a single cowl-inlet ram pressure ratio; independent control of engine speed and fuel flow was used to obtain a range of powers at each engine speed. Engine performance data obtained at a given altitude could not be used to predict performance accurately at other altitudes by use of the standard air pressure and temperature generalizing factors. At a given engine speed and turbine-inlet total temperature, a greater portion of the total available energy was converted to propulsive power as the altitude increased.

Autophagy Is a Promoter for Aerobic Exercise Performance during High Altitude Training

PubMed Central

Zhang, Ying

2018-01-01

High altitude training is one of the effective strategies for improving aerobic exercise performance at sea level via altitude acclimatization, thereby improving oxygen transport and/or utilization. But its underlying molecular mechanisms on physiological functions and exercise performance of athletes are still vague. More recent evidence suggests that the recycling of cellular components by autophagy is an important process of the body involved in the adaptive responses to exercise. Whether high altitude training can activate autophagy or whether high altitude training can improve exercise performance through exercise-induced autophagy is still unclear. In this narrative review article, we will summarize current research advances in the improvement of exercise performance through high altitude training and its reasonable molecular mechanisms associated with autophagy, which will provide a new field to explore the molecular mechanisms of adaptive response to high altitude training. PMID:29849885

Canadian Academy of Sport and Exercise Medicine position statement: athletes at high altitude.

PubMed

Koehle, Michael S; Cheng, Ivy; Sporer, Benjamin

2014-03-01

Many sports incorporate training at altitude as a key component of their athlete training plan. Furthermore, many sports are required to compete at high altitude venues. Exercise at high altitude provides unique challenges to the athlete and to the sport medicine clinician working with these athletes. These challenges include altitude illness, alterations in training intensity and performance, nutritional and hydration difficulties, and challenges related to the austerity of the environment. Furthermore, many of the strategies that are typically utilized by visitors to altitude may have implications from an anti-doping point of view.This position statement was commissioned and approved by the Canadian Academy of Sport and Exercise Medicine. The purpose of this statement was to provide an evidence-based, best practices summary to assist clinicians with the preparation and management of athletes and individuals travelling to altitude for both competition and training.

High Altitude Remains Associated with Elevated Suicide Rates after Adjusting for Socioeconomic Status: A Study from South Korea

PubMed Central

Kim, Jaelim; Choi, Nari; Lee, Yu-Jin; An, Hyonggin; Kim, Namkug; Yoon, Ho-Kyoung

2014-01-01

There have been several studies supporting a possible relationship between high suicide rate and high altitude. However socioeconomic status may confound this association because low socioeconomic status, which is known to be related to a high suicide rate, is also associated with living at high altitude. This study aims to explore whether the relationship between high altitude and high suicide rate remains after adjusting for socioeconomic status in South Korea. We collected demographic data of completed suicides, the mean altitude of the district where each suicide took place, and the mean income of each district. We analyzed the data using regression analysis before and after adjustment for mean income. We found that there is a positive correlation between altitude and suicide rate, even after adjustment for mean income. Thus, altitude appears to be an independent risk factor for suicide. PMID:25395983

14 CFR 91.119 - Minimum safe altitudes: General.

Code of Federal Regulations, 2011 CFR

2011-01-01

... persons, an altitude of 1,000 feet above the highest obstacle within a horizontal radius of 2,000 feet of... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Minimum safe altitudes: General. 91.119... § 91.119 Minimum safe altitudes: General. Except when necessary for takeoff or landing, no person may...

Human Behaviour and Development under High-Altitude Conditions

ERIC Educational Resources Information Center

Virues-Ortega, Javier; Garrido, Eduardo; Javierre, Casimiro; Kloezeman, Karen C.

2006-01-01

Although we are far from a universally accepted pattern of impaired function at altitude, there is evidence indicating motor, perceptual, memory and behavioural deficits in adults. Even relatively low altitudes (2500 m) may delay reaction time, and impair motor function. Extreme altitude exposure (greater than 5000 m) may result in more pronounced…

76 FR 80732 - Revocation and Establishment of Compulsory Reporting Point; Alaska

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-27

... low altitude and a high altitude Alaskan compulsory reporting point in the vicinity of Kodiak, Alaska...-8783. SUPPLEMENTARY INFORMATION: History The FAA has determined that the low and high altitude Alaska..., the FAA is changing the name of the low and high altitude MARLO compulsory reporting point in the...

14 CFR 91.119 - Minimum safe altitudes: General.

Code of Federal Regulations, 2010 CFR

2010-01-01

... persons, an altitude of 1,000 feet above the highest obstacle within a horizontal radius of 2,000 feet of... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Minimum safe altitudes: General. 91.119... § 91.119 Minimum safe altitudes: General. Except when necessary for takeoff or landing, no person may...

Effects of High Terrestrial Altitude on Military Performance

DTIC Science & Technology

1989-04-18

ments were observed. In a second study at the same altitude neither age nor altitude changed urinary 17- ketogenic steroid excretion rates or Fatigue...due to decreased food intake) and up to 5 liters of water per day may be required. A balanced diet at high altitude is 52% car- bohydrates, 33% fats

14 CFR 23.841 - Pressurized cabins.

Code of Federal Regulations, 2012 CFR

2012-01-01

... descent is made by an approved emergency procedure. A 17-second flight crew recognition and reaction time... altitude-time history shown in Figure 1 of this section. (ii) Maximum cabin altitude is limited to 30,000 feet. If cabin altitude exceeds 25,000 feet, the maximum time the cabin altitude may exceed 25,000 feet...

40 CFR 1054.655 - What special provisions apply for installing and removing altitude kits?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 33 2014-07-01 2014-07-01 false What special provisions apply for installing and removing altitude kits? 1054.655 Section 1054.655 Protection of Environment ENVIRONMENTAL... installing and removing altitude kits? An action for the purpose of installing or modifying altitude kits and...

40 CFR 1054.655 - What special provisions apply for installing and removing altitude kits?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 34 2012-07-01 2012-07-01 false What special provisions apply for installing and removing altitude kits? 1054.655 Section 1054.655 Protection of Environment ENVIRONMENTAL... installing and removing altitude kits? An action for the purpose of installing or modifying altitude kits and...

40 CFR 1054.655 - What special provisions apply for installing and removing altitude kits?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 34 2013-07-01 2013-07-01 false What special provisions apply for installing and removing altitude kits? 1054.655 Section 1054.655 Protection of Environment ENVIRONMENTAL... installing and removing altitude kits? An action for the purpose of installing or modifying altitude kits and...

40 CFR 1054.655 - What special provisions apply for installing and removing altitude kits?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false What special provisions apply for installing and removing altitude kits? 1054.655 Section 1054.655 Protection of Environment ENVIRONMENTAL... installing and removing altitude kits? An action for the purpose of installing or modifying altitude kits and...

40 CFR 1054.655 - What special provisions apply for installing and removing altitude kits?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 33 2011-07-01 2011-07-01 false What special provisions apply for installing and removing altitude kits? 1054.655 Section 1054.655 Protection of Environment ENVIRONMENTAL... installing and removing altitude kits? An action for the purpose of installing or modifying altitude kits and...

VIEW OF THE TOPS OF ALTITUDE CHAMBER R (TO LEFT) ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF THE TOPS OF ALTITUDE CHAMBER R (TO LEFT) AND ALTITUDE CHAMBER L (TO RIGHT) FROM THE 42’-0” LEVEL OF ACCESS PLATFORMS, FACING NORTHWEST - Cape Canaveral Air Force Station, Launch Complex 39, Altitude Chambers, First Street, between Avenue D and Avenue E, Cape Canaveral, Brevard County, FL

High Altitude Launch for a Practical SSTO

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.; Denis, Vincent

2003-01-01

Existing engineering materials allow the construction of towers to heights of many kilometers. Orbital launch from a high altitude has significant advantages over sea-level launch due to the reduced atmospheric pressure, resulting in lower atmospheric drag on the vehicle and allowing higher rocket engine performance. High-altitude launch sites are particularly advantageous for single-stage to orbit (SSTO) vehicles, where the payload is typically 2 percent of the initial launch mass. An earlier paper enumerated some of the advantages of high altitude launch of SSTO vehicles. In this paper, we calculate launch trajectories for a candidate SSTO vehicle, and calculate the advantage of launch at launch altitudes 5 to 25 kilometer altitudes above sea level. The performance increase can be directly translated into increased payload capability to orbit, ranging from 5 to 20 percent increase in the mass to orbit. For a candidate vehicle with an initial payload fraction of 2 percent of gross lift-off weight, this corresponds to 31 percent increase in payload (for 5-kilometer launch altitude) to 122 percent additional payload (for 25-kilometer launch altitude).

High Altitude Launch for a Practical SSTO

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.; Denis, Vincent

2003-01-01

Existing engineering materials allow the construction of towers to heights of many kilometers. Orbital launch from a high altitude has significant advantages over sea-level launch due to the reduced atmospheric pressure, resulting in lower atmospheric drag on the vehicle and allowing higher rocket engine performance. high-altitude launch sites are particularly advantageous for single-stage to orbit (SSTO) vehicles, where the payload is typically 2% of the initial launch mass. An earlier paper enumerated some of the advantages of high altitude launch of SSTO vehicles. In this paper, we calculate launch trajectories for a candidate SSTO vehicle, and calculate the advantage of launch at launch altitudes 5 to 25 kilometer altitudes above sea level. The performance increase can be directly translated in to increased payload capability to orbit, ranging from 5 to 20% increase in the mass to orbit. For a candidate vehicle with an initial payload fraction of 2% of gross lift-off weight, this corresponds to 31 % increase in payload (for 5-km launch altitude) to 122% additional payload (for 25-km launch altitude).

Bronchopulmonary dysplasia: effect of altitude correction and role for the Neonatal Research Network Prediction Algorithm.

PubMed

Gulliver, Kristina; Yoder, Bradley A

2018-05-09

To determine the effect of altitude correction on bronchopulmonary dysplasia (BPD) rates and to assess validity of the NICHD "Neonatal BPD Outcome Estimator" for predicting BPD with and without altitude correction. Retrospective analysis included neonates born <30 weeks gestational age (GA) between 2010 and 2016. "Effective" FiO 2 requirements were determined at 36 weeks corrected GA. Altitude correction performed via ratio of barometric pressure (BP) in our unit to sea level BP. Probability of death and/or moderate-to-severe BPD was calculated using the NICHD BPD Outcome Estimator. Five hundred and sixty-one infants were included. Rate of moderate-to-severe BPD decreased from 71 to 40% following altitude correction. Receiver-operating characteristic curves indicated high predictability of BPD Outcome Estimator for altitude-corrected moderate-to-severe BPD diagnosis. Correction for altitude reduced moderate-to-severe BPD rate by almost 50%, to a rate consistent with recent published values. NICHD BPD Outcome Estimator is a valid tool for predicting the risk of moderate-to-severe BPD following altitude correction.

The influence of altitude of the place on the vegetative growth of several varieties of sugarcane (saccharum officinarum l.)

NASA Astrophysics Data System (ADS)

Panataria, Lince R.; Lubis, Ramli

2018-03-01

This study is aimed at finding out vegetative growth of some varieties of sugarcane on different altitudes. The study applied Factorial Randomized Block Design comprising two factors. The first factor was varieties of consisting of three levels: BM 13579, Ps. 92-1, and Ps. 89-1. The second factor was altitudes of the land with three different levels of altitudes: Kebun Saentis (15 MASL), district of Pancurbatu (±300 MASL), and district of Sibolangit (±700 MASL). The study resulted in that variety of sugarcane, altitudes, and the interaction of both variables affected these: the leaf area on observations of 21, 42, 63, and 84 daps, number of tillers, root volume, nutrient uptake on observation 84 daps. The best quality of the sugarcane varieties was variety Ps. 92-1 on altitude 15 MASL (Kebun Saentis), followed by an altitude ±300 MASL (district of Pancurbatu), and then on ±700 MASL (district of Sibolangit); while the worst quality of the variety was variety BM 13579 of altitude 15 MASL (Kebun Saentis).

Exploring the Limits of High Altitude GPS for Future Lunar Missions

NASA Technical Reports Server (NTRS)

Ashman, Benjamin W.; Parker, Joel J.; Bauer, Frank H.; Esswein, Michael

2018-01-01

An increasing number of spacecraft are relying on the Global Positioning System (GPS) for navigation at altitudes near or above the GPS constellation itself - the region known as the Space Service Volume (SSV). While the formal definition of the SSV ends at geostationary altitude, the practical limit of high-altitude space usage is not known, and recent missions have demonstrated that signal availability is sufficient for operational navigation at altitudes halfway to the moon. This paper presents simulation results based on a high-fidelity model of the GPS constellation, calibrated and validated through comparisons of simulated GPS signal availability and strength with flight data from recent high-altitude missions including the Geostationary Operational Environmental Satellite 16 (GOES-16) and the Magnetospheric Multiscale (MMS) mission. This improved model is applied to the transfer to a lunar near-rectilinear halo orbit (NRHO) of the class being con- sidered for the international Deep Space Gateway concept. The number of GPS signals visible and their received signal strengths are presented as a function of receiver altitude in order to explore the practical upper limit of high-altitude space usage of GPS.

Effects of high altitude and exercise on marksmanship.

PubMed

Tharion, W J; Hoyt, R W; Marlowe, B E; Cymerman, A

1992-02-01

The effects of exercise and high altitude (3,700 m to 4,300 m) on marksmanship accuracy and sighting time were quantified in 16 experienced marksmen. Subjects dry-fired a disabled rifle equipped with a laser-based system from a free-standing position. The 2.3-cm circular target was at a distance of 5 m. Marksmanship was assessed under the following conditions: 1) at rest at sea level; 2) immediately after a 21-km run/walk ascent from 1,800 m to 4,300 m elevation; 3) at rest during days 1 to 3 at altitude; 4) at rest during days 14 to 16 at altitude; and 5) immediately after a second ascent after 17 d at altitude. Exercise reduced marksmanship accuracy (p less than 0.05) but did not affect sighting time. Acute altitude exposure reduced marksmanship accuracy, and decreased sighting time (p less than 0.05). However, after residence at altitude, accuracy and sighting time at rest returned to sea level values. Exercise and acute altitude exposure had similar but independent detrimental effects on marksmanship.

Exploring the Limits of High Altitude GPS for Future Lunar Missions

NASA Technical Reports Server (NTRS)

Ashman, Benjamin W.; Parker, Joel J. K.; Bauer, Frank H.; Esswein, Michael

2018-01-01

An increasing number of spacecraft are relying on the Global Positioning System (GPS) for navigation at altitudes near or above the GPS constellation itself - the region known as the Space Service Volume (SSV). While the formal definition of the SSV ends at geostationary altitude, the practical limit of high-altitude space usage is not known, and recent missions have demonstrated that signal availability is sufficient for operational navigation at altitudes halfway to the moon. This paper presents simulation results based on a high-fidelity model of the GPS constellation, calibrated and validated through comparisons of simulated GPS signal availability and strength with flight data from recent high-altitude missions including the Geostationary Operational Environmental Satellite 16 (GOES-16) and the Magnetospheric Multiscale (MMS) mission. This improved model is applied to the transfer to a lunar near-rectilinear halo orbit (NRHO) of the class being considered for the international Deep Space Gateway concept. The number of GPS signals visible and their received signal strengths are presented as a function of receiver altitude in order to explore the practical upper limit of high-altitude space usage of GPS.

Physiological Changes to the Cardiovascular System at High Altitude and Its Effects on Cardiovascular Disease.

PubMed

Riley, Callum James; Gavin, Matthew

2017-06-01

Riley, Callum James, and Matthew Gavin. Physiological changes to the cardiovascular system at high altitude and its effects on cardiovascular disease. High Alt Med Biol. 18:102-113, 2017.-The physiological changes to the cardiovascular system in response to the high altitude environment are well understood. More recently, we have begun to understand how these changes may affect and cause detriment to cardiovascular disease. In addition to this, the increasing availability of altitude simulation has dramatically improved our understanding of the physiology of high altitude. This has allowed further study on the effect of altitude in those with cardiovascular disease in a safe and controlled environment as well as in healthy individuals. Using a thorough PubMed search, this review aims to integrate recent advances in cardiovascular physiology at altitude with previous understanding, as well as its potential implications on cardiovascular disease. Altogether, it was found that the changes at altitude to cardiovascular physiology are profound enough to have a noteworthy effect on many forms of cardiovascular disease. While often asymptomatic, there is some risk in high altitude exposure for individuals with certain cardiovascular diseases. Although controlled research in patients with cardiovascular disease was largely lacking, meaning firm conclusions cannot be drawn, these risks should be a consideration to both the individual and their physician.

Text mining and network analysis to find functional associations of genes in high altitude diseases.

PubMed

Bhasuran, Balu; Subramanian, Devika; Natarajan, Jeyakumar

2018-05-02

Travel to elevations above 2500 m is associated with the risk of developing one or more forms of acute altitude illness such as acute mountain sickness (AMS), high altitude cerebral edema (HACE) or high altitude pulmonary edema (HAPE). Our work aims to identify the functional association of genes involved in high altitude diseases. In this work we identified the gene networks responsible for high altitude diseases by using the principle of gene co-occurrence statistics from literature and network analysis. First, we mined the literature data from PubMed on high-altitude diseases, and extracted the co-occurring gene pairs. Next, based on their co-occurrence frequency, gene pairs were ranked. Finally, a gene association network was created using statistical measures to explore potential relationships. Network analysis results revealed that EPO, ACE, IL6 and TNF are the top five genes that were found to co-occur with 20 or more genes, while the association between EPAS1 and EGLN1 genes is strongly substantiated. The network constructed from this study proposes a large number of genes that work in-toto in high altitude conditions. Overall, the result provides a good reference for further study of the genetic relationships in high altitude diseases. Copyright © 2018 Elsevier Ltd. All rights reserved.

[Hemoglobin and testosterone: importance on high altitude acclimatization and adaptation].

PubMed

Gonzales, Gustavo F

2011-03-01

The different types of response mechanisms that the organism uses when exposed to hypoxia include accommodation, acclimatization and adaptation. Accommodation is the initial response to acute exposure to high altitude hypoxia and is characterized by an increase in ventilation and heart rate. Acclimatization is observed in individuals temporarily exposed to high altitude, and to some extent, it enables them to tolerate the high altitudes. In this phase, erythropoiesis is increased, resulting in higher hemoglobin and hematocrit levels to improve oxygen delivery capacity. Adaptation is the process of natural acclimatization where genetical variations and acclimatization play a role in allowing subjects to live without any difficulties at high altitudes. Testosterone is a hormone that regulates erythropoiesis and ventilation and could be associated to the processes of acclimatization and adaptation to high altitude. Excessive erythrocytosis, which leads to chronic mountain sickness, is caused by low arterial oxygen saturation, ventilatory inefficiency and reduced ventilatory response to hypoxia. Testosterone increases during acute exposure to high altitude and also in natives at high altitude with excessive erythrocytosis. Results of current research allow us to conclude that increase in serum testosterone and hemoglobin is adequate for acclimatization, as they improve oxygen transport, but not for high altitude adaptation, since high serum testosterone levels are associated to excessive erythrocytosis.

Hyperbaric oxygen therapy ameliorates acute brain injury after porcine intracerebral hemorrhage at high altitude.

PubMed

Zhu, Hai-tao; Bian, Chen; Yuan, Ji-chao; Liao, Xiao-jun; Liu, Wei; Zhu, Gang; Feng, Hua; Lin, Jiang-kai

2015-06-15

Intracerebral hemorrhage (ICH) at high altitude is not well understood to date. This study investigates the effects of high altitude on ICH, and examines the acute neuroprotection of hyperbaric oxygen (HBO) therapy against high-altitude ICH. Minipigs were placed in a hypobaric chamber for 72 h before the operation. ICH was induced by an infusion of autologous arterial blood (3 ml) into the right basal ganglia. Animals in the high-altitude ICH group received HBO therapy (2.5 ATA for 60 min) 30 min after ICH. Blood gas, blood glucose and brain tissue oxygen partial pressure (PbtO2) were monitored continuously for animals from all groups, as were microdialysis products including glucose, lactate, pyruvate and glutamate in perihematomal tissue from 3 to 12 h post-ICH. High-altitude ICH animals showed significantly lower PbtO2, higher lactate/pyruvate ratio (LPR) and glutamate levels than low-altitude ICH animals. More severe neurological deficits, brain edema and neuronal damage were also observed in high-altitude ICH. After HBO therapy, PbtO2 was significantly increased and LPR and glutamate levels were significantly decreased. Brain edema, neurological deficits and neuronal damage were also ameliorated. The data suggested a more serious disturbance of tissue oxygenation and cerebral metabolism in the acute stage after ICH at high altitude. Early HBO treatment reduced acute brain injury, perhaps through a mechanism involving the amelioration of the derangement of cerebral oxygenation and metabolism following high-altitude ICH.

Flying high: a theoretical analysis of the factors limiting exercise performance in birds at altitude.

PubMed

Scott, Graham R; Milsom, William K

2006-11-01

The ability of some bird species to fly at extreme altitude has fascinated comparative respiratory physiologists for decades, yet there is still no consensus about what adaptations enable high altitude flight. Using a theoretical model of O(2) transport, we performed a sensitivity analysis of the factors that might limit exercise performance in birds. We found that the influence of individual physiological traits on oxygen consumption (Vo2) during exercise differed between sea level, moderate altitude, and extreme altitude. At extreme altitude, haemoglobin (Hb) O(2) affinity, total ventilation, and tissue diffusion capacity for O(2) (D(To2)) had the greatest influences on Vo2; increasing these variables should therefore have the greatest adaptive benefit for high altitude flight. There was a beneficial interaction between D(To2) and the P(50) of Hb, such that increasing D(To2) had a greater influence on Vo2 when P(50) was low. Increases in the temperature effect on P(50) could also be beneficial for high flying birds, provided that cold inspired air at extreme altitude causes a substantial difference in temperature between blood in the lungs and in the tissues. Changes in lung diffusion capacity for O(2), cardiac output, blood Hb concentration, the Bohr coefficient, or the Hill coefficient likely have less adaptive significance at high altitude. Our sensitivity analysis provides theoretical suggestions of the adaptations most likely to promote high altitude flight in birds and provides direction for future in vivo studies.

Can patients with pulmonary hypertension travel to high altitude?

PubMed

Luks, Andrew M

2009-01-01

With the increasing popularity of adventure travel and mountain activities, it is likely that many high altitude travelers will have underlying medical problems and approach clinicians for advice about ensuring a safe sojourn. Patients with underlying pulmonary hypertension are one group who warrants significant concern during high altitude travel, because ambient hypoxia at high altitude will trigger hypoxic pulmonary vasoconstriction and cause further increases in pulmonary artery (PA) pressure, which may worsen hemodynamics and also predispose to acute altitude illness. After addressing basic information about pulmonary hypertension and pulmonary vascular responses to acute hypoxia, this review discusses the evidence supporting an increased risk for high altitude pulmonary edema in these patients, concerns regarding worsening oxygenation and right-heart function, the degree of underlying pulmonary hypertension necessary to increase risk, and the altitude at which such problems may occur. These patients may be able to travel to high altitude, but they require careful pre-trip assessment, including echocardiography and, when feasible, high altitude simulation testing with echocardiography to assess changes in PA pressure and oxygenation under hypoxic conditions. Those with mean PA pressure > or =35 mm Hg or systolic PA pressure > or =50 mm Hg at baseline should avoid travel to >2000 m; but if such travel is necessary or strongly desired, they should use supplemental oxygen during the sojourn. Patients with milder degrees of pulmonary hypertension may travel to altitudes <3000 m, but should consider prophylactic measures, including pulmonary vasodilators or supplemental oxygen.

Integrating the effects of latitude and altitude on the spatial differentiation of plant community diversity in a mountainous ecosystem in China

PubMed Central

Xu, Manhou; Ma, Li; Jia, Yanyan; Liu, Min

2017-01-01

Varying patterns of plant community diversity along geographical gradients are a significant topic in biodiversity research. Here, to explore the integrated effects of latitude and altitude on the plant community diversity in a mountainous ecosystem, we set Guancen Mountain in the northern section, Guandi Mountain in the middle section, and Wulu Mountain in the southern section of the Lvliang Mountains as study areas, and the plant community diversity (basal diameter and height of tree and species diversity indices of shrub and herb) was measured horizontally at different latitude gradients and vertically at different altitude gradients in late July 2015. The results showed that (1) the trees were taller and wider at the middle latitude and higher altitude with a stronger spatial heterogeneity in the structures along the latitudinal and altitudinal gradients. The evergreen tree growth preceded that of the deciduous trees in the higher latitude and lower altitude regions, whereas the deciduous tree growth preceded that of the evergreen trees in the middle latitude and higher altitude regions. (2) Shrubs and herbs tended to grow well in the lower latitude and middle-lower altitude regions. The shrubs had a larger species diversity at lower latitude and lower altitude, but the species diversity of the herbs was not sensitive to the influences of the latitudinal and altitudinal gradients. With the latitude and altitude increasing, perennial herbs tended to grow well at higher latitude and higher altitude, while annual herbs tended to thrive at the middle latitude and lower altitude. In conclusion, environmental deviations caused by latitudinal and altitudinal gradients had great influences on the spatial distributions of the plant community diversity in the Lvliang Mountains. PMID:28323909

Soccer activity profile of altitude versus sea-level natives during acclimatisation to 3600 m (ISA3600)

PubMed Central

Aughey, Robert J; Hammond, Kristal; Varley, Matthew C; Schmidt, Walter F; Bourdon, Pitre C; Buchheit, Martin; Simpson, Ben; Garvican-Lewis, Laura A; Kley, Marlen; Soria, Rudy; Sargent, Charli; Roach, Gregory D; Claros, Jesus C Jimenez; Wachsmuth, Nadine; Gore, Christopher J

2013-01-01

Objectives We investigated the effect of high altitude on the match activity profile of elite youth high altitude and sea level residents. Methods Twenty Sea Level (Australian) and 19 Altitude-resident (Bolivian) soccer players played five games, two near sea level (430 m) and three in La Paz (3600 m). Match activity profile was quantified via global positioning system with the peak 5 min period for distance ((D5peak)) and high velocity running (>4.17 m/s, HIVR5peak); as well as the 5 min period immediately subsequent to the peak for both distance (D5sub) and high-velocity running (HIVR5sub) identified using a rolling 5 min epoch. The games at 3600 m were compared with the average of the two near sea-level games. Results The total distance per minute was reduced by a small magnitude in the first match at altitude in both teams, without any change in low-velocity running. There were variable changes in HiVR, D5peak and HiVR5peak from match to match for each team. There were within-team reductions in D5peak in each game at altitude compared with those at near sea level, and this reduction was greater by a small magnitude in Australians than Bolivians in game 4. The effect of altitude on HiVR5peak was moderately lower in Australians compared with Bolivians in game 3. There was no clear difference in the effect of altitude on maximal accelerations between teams. Conclusions High altitude reduces the distance covered by elite youth soccer players during matches. Neither 13 days of acclimatisation nor lifelong residence at high altitude protects against detrimental effects of altitude on match activity profile. PMID:24282196

Comparative transcriptomics of 5 high-altitude vertebrates and their low-altitude relatives

PubMed Central

Tang, Qianzi; Zhou, Xuming; Jin, Long; Guan, Jiuqiang; Liu, Rui; Li, Jing; Long, Kereng; Tian, Shilin; Che, Tiandong; Hu, Silu; Liang, Yan; Yang, Xuemei; Tao, Xuan; Zhong, Zhijun; Wang, Guosong; Chen, Xiaohui; Li, Diyan; Ma, Jideng; Wang, Xun; Mai, Miaomiao; Jiang, An’an; Luo, Xiaolin; Lv, Xuebin; Gladyshev, Vadim N; Li, Xuewei

2017-01-01

Abstract Background Species living at high altitude are subject to strong selective pressures due to inhospitable environments (e.g., hypoxia, low temperature, high solar radiation, and lack of biological production), making these species valuable models for comparative analyses of local adaptation. Studies that have examined high-altitude adaptation have identified a vast array of rapidly evolving genes that characterize the dramatic phenotypic changes in high-altitude animals. However, how high-altitude environment shapes gene expression programs remains largely unknown. Findings We generated a total of 910 Gb of high-quality RNA-seq data for 180 samples derived from 6 tissues of 5 agriculturally important high-altitude vertebrates (Tibetan chicken, Tibetan pig, Tibetan sheep, Tibetan goat, and yak) and their cross-fertile relatives living in geographically neighboring low-altitude regions. Of these, ∼75% reads could be aligned to their respective reference genomes, and on average ∼60% of annotated protein coding genes in each organism showed FPKM expression values greater than 0.5. We observed a general concordance in topological relationships between the nucleotide alignments and gene expression–based trees. Tissue and species accounted for markedly more variance than altitude based on either the expression or the alternative splicing patterns. Cross-species clustering analyses showed a tissue-dominated pattern of gene expression and a species-dominated pattern for alternative splicing. We also identified numerous differentially expressed genes that could potentially be involved in phenotypic divergence shaped by high-altitude adaptation. Conclusions These data serve as a valuable resource for examining the convergence and divergence of gene expression changes between species as they adapt or acclimatize to high-altitude environments. PMID:29149296

Integrating the effects of latitude and altitude on the spatial differentiation of plant community diversity in a mountainous ecosystem in China.

PubMed

Xu, Manhou; Ma, Li; Jia, Yanyan; Liu, Min

2017-01-01

Varying patterns of plant community diversity along geographical gradients are a significant topic in biodiversity research. Here, to explore the integrated effects of latitude and altitude on the plant community diversity in a mountainous ecosystem, we set Guancen Mountain in the northern section, Guandi Mountain in the middle section, and Wulu Mountain in the southern section of the Lvliang Mountains as study areas, and the plant community diversity (basal diameter and height of tree and species diversity indices of shrub and herb) was measured horizontally at different latitude gradients and vertically at different altitude gradients in late July 2015. The results showed that (1) the trees were taller and wider at the middle latitude and higher altitude with a stronger spatial heterogeneity in the structures along the latitudinal and altitudinal gradients. The evergreen tree growth preceded that of the deciduous trees in the higher latitude and lower altitude regions, whereas the deciduous tree growth preceded that of the evergreen trees in the middle latitude and higher altitude regions. (2) Shrubs and herbs tended to grow well in the lower latitude and middle-lower altitude regions. The shrubs had a larger species diversity at lower latitude and lower altitude, but the species diversity of the herbs was not sensitive to the influences of the latitudinal and altitudinal gradients. With the latitude and altitude increasing, perennial herbs tended to grow well at higher latitude and higher altitude, while annual herbs tended to thrive at the middle latitude and lower altitude. In conclusion, environmental deviations caused by latitudinal and altitudinal gradients had great influences on the spatial distributions of the plant community diversity in the Lvliang Mountains.

Supplemental oxygen effect on hypoxemia at moderate altitude in patients with COPD.

PubMed

Kelly, Paul T; Swanney, Maureen P; Stanton, Josh D; Frampton, Chris; Peters, Matthew J; Beckert, Lutz E

2009-09-01

Altitude exposure will cause moderate to severe hypoxemia in patients with chronic obstructive pulmonary disease (COPD). Supplemental oxygen can be used to attenuate this hypoxemia; however, individual response is variable and difficult to predict. The aim of this study was to assess the efficacy of oxygen supplementation in patients with COPD at a barometric pressure similar to that of a commercial aircraft cabin. Following sea-level (40 m) arterial blood gases measurements, 18 patients with COPD were driven to altitude (2086 m), where blood gases were repeated at rest and while on 2 L x min(-1) of supplementary oxygen (altitude O2). Ascent from sea level to altitude caused significant hypoxemia (75 +/- 9 vs. 51 +/- 6 mmHg), which was partially reversed by supplemental oxygen (64 +/- 9 mmHg). Oxygen supplementation did not significantly alter PaCO2 levels (vs. altitude PaCO2). There was a significant relationship between the sea-level CaO2 versus the altitude O2 CaO2 (r = 0.89, P < 0.001). There was a significant relationship (r = 0.81, P < 0.001) between altitude-induced desaturation and resaturation with the administration of oxygen. There was a significant negative correlation (r = -0.74, P < 0.001) between baseline K(CO) and the improvement in CaO2 with the administration of oxygen. Low-flow supplemental oxygen during acute altitude exposure will partially reverse altitude-induced hypoxemia in patients with COPD. Patients with diffusion impairments are likely to experience the greatest altitude desaturation, but will gain the most benefit from supplemental oxygen. Supplemental oxygen, delivered at 2 L x min(-1), should maintain clinically acceptable oxygenation during commercial air travel in patients with COPD.

Outdoor Activity and High Altitude Exposure During Pregnancy: A Survey of 459 Pregnancies.

PubMed

Keyes, Linda E; Hackett, Peter H; Luks, Andrew M

2016-06-01

To evaluate whether women engage in outdoor activities and high altitude travel during pregnancy; the health care advice received regarding high altitude during pregnancy; and the association between high altitude exposure and self-reported pregnancy complications. An online survey of women with at least 1 pregnancy distributed on websites and e-mail lists targeting mothers and/or mountain activities. Outcome measures were outdoor activities during pregnancy, high altitude (>2440 m) exposure during pregnancy, and pregnancy and perinatal complications. Hiking, running, and swimming were the most common activities performed during pregnancy. Women traveled to high altitude in over half of the pregnancies (244/459), and most did not receive counseling regarding altitude (355, 77%), although a small proportion (14, 3%) were told not to go above 2440 m. Rates of miscarriage and most other complications were similar between pregnancies with and without travel above 2440 m. Pregnancies with high altitude exposure were more likely to have preterm labor (odds ratio [OR] 2.3; 95% CI 0.97-5.4; P = .05). Babies born to women who went to high altitude during pregnancy were more likely to need oxygen at birth (OR 2.34; 95% CI 1.04-5.26; P < .05) but had similar rates of neonatal intensive care unit admission (P = not significant). Our results suggest pregnant women who are active in outdoor sports and travel to high altitude have a low rate of complications. Given the limitations of our data, further research is necessary on the risks associated with high altitude travel and physical activity and how these apply to the general population. Copyright © 2016 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

Impact of a Newly Constructed Motor Vehicle Road on Altitude Illness in the Nepal Himalayas.

PubMed

Reisman, Jonathan; Deonarain, Dinesh; Basnyat, Buddha

2017-12-01

This study investigated the impact that motor vehicle travel along a newly constructed road has on altitude illness (including acute mountain sickness, high-altitude cerebral edema, and high-altitude pulmonary edema). The new road from Besisahar (760 m) to Manang (3540 m) in Nepal was completed in December 2014. We enrolled all patients diagnosed with altitude illness at the Himalayan Rescue Association Manang clinic in fall 2016. Phi coefficients were calculated to test for an association between Nepali ethnicity and rapid ascent by motor vehicle. A retrospective review looked at all patients with altitude illness from fall (September-November) 2010 to spring (February-May) 2016. In fall 2016, more than half (54%) of patients with altitude illness traveled to Manang by motor vehicle, and one-third (33%) reached Manang from low altitude (Besisahar) in less than 48 hours. Nepali nationality had a significant association with motor vehicle travel (phi +0.69, P < .0001) as well as with rapid ascent to Manang (phi +0.72, P < .0001). Compared to previous seasons, fall 2016 saw the most patients diagnosed with altitude illness. The proportion of people with altitude illness who traveled by vehicle and reached Manang in less than 48 hours was significantly greater than the proportion prior to completion of the road (P < .0001 for both). Rapid ascent by the newly constructed road from Besisahar to Manang appears to be related to a significant increase in the number of patients with all forms of altitude illness, especially among Nepalis. The authors believe that educational interventions emphasizing prevention are urgently needed. Copyright © 2017 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

Soccer activity profile of altitude versus sea-level natives during acclimatisation to 3600 m (ISA3600).

PubMed

Aughey, Robert J; Hammond, Kristal; Varley, Matthew C; Schmidt, Walter F; Bourdon, Pitre C; Buchheit, Martin; Simpson, Ben; Garvican-Lewis, Laura A; Kley, Marlen; Soria, Rudy; Sargent, Charli; Roach, Gregory D; Claros, Jesus C Jimenez; Wachsmuth, Nadine; Gore, Christopher J

2013-12-01

We investigated the effect of high altitude on the match activity profile of elite youth high altitude and sea level residents. Twenty Sea Level (Australian) and 19 Altitude-resident (Bolivian) soccer players played five games, two near sea level (430 m) and three in La Paz (3600 m). Match activity profile was quantified via global positioning system with the peak 5 min period for distance ((D₅(peak)) and high velocity running (>4.17 m/s, HIVR₅(peak)); as well as the 5 min period immediately subsequent to the peak for both distance (D₅(sub)) and high-velocity running (HIVR₅(sub)) identified using a rolling 5 min epoch. The games at 3600 m were compared with the average of the two near sea-level games. The total distance per minute was reduced by a small magnitude in the first match at altitude in both teams, without any change in low-velocity running. There were variable changes in HiVR, D₅(peak) and HiVR₅(peak) from match to match for each team. There were within-team reductions in D₅(peak) in each game at altitude compared with those at near sea level, and this reduction was greater by a small magnitude in Australians than Bolivians in game 4. The effect of altitude on HiVR₅(peak) was moderately lower in Australians compared with Bolivians in game 3. There was no clear difference in the effect of altitude on maximal accelerations between teams. High altitude reduces the distance covered by elite youth soccer players during matches. Neither 13 days of acclimatisation nor lifelong residence at high altitude protects against detrimental effects of altitude on match activity profile.

Comparative transcriptomics of 5 high-altitude vertebrates and their low-altitude relatives.

PubMed

Tang, Qianzi; Gu, Yiren; Zhou, Xuming; Jin, Long; Guan, Jiuqiang; Liu, Rui; Li, Jing; Long, Kereng; Tian, Shilin; Che, Tiandong; Hu, Silu; Liang, Yan; Yang, Xuemei; Tao, Xuan; Zhong, Zhijun; Wang, Guosong; Chen, Xiaohui; Li, Diyan; Ma, Jideng; Wang, Xun; Mai, Miaomiao; Jiang, An'an; Luo, Xiaolin; Lv, Xuebin; Gladyshev, Vadim N; Li, Xuewei; Li, Mingzhou

2017-12-01

Species living at high altitude are subject to strong selective pressures due to inhospitable environments (e.g., hypoxia, low temperature, high solar radiation, and lack of biological production), making these species valuable models for comparative analyses of local adaptation. Studies that have examined high-altitude adaptation have identified a vast array of rapidly evolving genes that characterize the dramatic phenotypic changes in high-altitude animals. However, how high-altitude environment shapes gene expression programs remains largely unknown. We generated a total of 910 Gb of high-quality RNA-seq data for 180 samples derived from 6 tissues of 5 agriculturally important high-altitude vertebrates (Tibetan chicken, Tibetan pig, Tibetan sheep, Tibetan goat, and yak) and their cross-fertile relatives living in geographically neighboring low-altitude regions. Of these, ∼75% reads could be aligned to their respective reference genomes, and on average ∼60% of annotated protein coding genes in each organism showed FPKM expression values greater than 0.5. We observed a general concordance in topological relationships between the nucleotide alignments and gene expression-based trees. Tissue and species accounted for markedly more variance than altitude based on either the expression or the alternative splicing patterns. Cross-species clustering analyses showed a tissue-dominated pattern of gene expression and a species-dominated pattern for alternative splicing. We also identified numerous differentially expressed genes that could potentially be involved in phenotypic divergence shaped by high-altitude adaptation. These data serve as a valuable resource for examining the convergence and divergence of gene expression changes between species as they adapt or acclimatize to high-altitude environments. © The Authors 2017. Published by Oxford University Press.

Genetic diversities of MT-ND1 and MT-ND2 genes are associated with high-altitude adaptation in yak.

PubMed

Shi, Yu; Hu, Yongsong; Wang, Jie; Elzo, Mauricio A; Yang, Xue; Lai, Songjia

2018-04-01

Tibetan yak (Bos grunniens) inhabiting the Qinghai-Tibet Plateau (QTP) where the average altitude is 4000 m, is specially adapted to live at these altitudes. Conversely, cattle (B. taurus) has been found to suffer from high-altitude hypertension or heart failure when exposed to these high altitudes. Two mitochondrial genes, MT-ND1 and MT-ND2, encode two subunits of NADH dehydrogenase play an essential role in the electron transport chain of oxidative phosphorylation (OXPHOS). We sequenced these two mitochondrial genes in two bovine groups (70 Tibetan yaks and 70 Xuanhan cattle) and downloaded 300 sequences of B. taurus (cattle), 93 sequences of B. grunniens (domestic yak), and 2 sequences of B. mutus (wild yak) from NCBI to increase our understanding of the mechanisms of adaptability to hypoxia at high altitudes in yaks compared to cattle. MT-ND1 SNP m.3907 C > T, present in all Tibetan yaks, was positively associated with high-altitude adaptation (p < .0006). Specially, mutation m.3638 A > G present in all cattle, resulting in the termination of transcription, was negatively associated with high-altitude adaptation (p < .0006). Additionally, MT-ND2 SNPs m.4351 G > A and m.5218 C > T also showed positive associations with high-altitude adaptation (p < .0004). MT-ND1 haplotypes H2, H3, H4, H6, and H7 showed positive associations but haplotype H20 had a negative association with high-altitude adaptation (p < .0008). Similarly, MT-ND2 haplotypes Ha1 Ha8, Ha10, and Ha11 were positively associated whereas haplotype Ha2 was negatively associated with adaptability to high-altitudes (p < .0008). Thus, MT-ND1 and MT-ND2 can be considered as candidate genes associated with adaptation to high-altitude environments.

Evaluation of hemoglobin concentration in pregnancy and correlation with different altitude: a study from balochistan plateau of pakistan.

PubMed

Umar, Zubaida; Rasool, Mahmood; Asif, Muhammad; Karim, Sajjad; Malik, Arif; Mushtaq, Gohar; Kamal, Mohammad A; Mansoor, Arsala

2015-01-01

Anemia refers to a condition having low hemoglobin concentration. Anemia is considered a major risk factor for unfavorable pregnancy outcomes. This is the first study describing the pattern of hemoglobin concentration during pregnancy and its relationship to areas of high and low altitudes in Balochistan (the largest of Pakistan's four provinces). The main objective of this study was to observe hemoglobin levels and prevalence of anemia among pregnant women living in the high or low altitude areas of Balochistan. A randomized survey was conducted and blood samples were collected from 132 healthy full term pregnant women subjects and 110 unmarried females. The subjects of the current study were selected from two different areas of Balochistan (Quetta and Uthal). Hemoglobin levels of the subjects were analyzed on Microlab 300 by Merck kit. Dietary status of the subjects was assessed based on simplified associated food frequency questionnaire. The factors effecting hemoglobin in full term pregnancy at different altitudes were multi gravidity/parity (increased number of pregnancies/children), age, socio-economic and educational status. Anemia was highly prevalent in low-altitude region (68.33%). We found statistically significant difference in mean hemoglobin level at high-altitude region (11.81 ± 1.02) and low-altitude region (10.20 ± 1.28) in pregnant females of Balochistan plateau (P < 0.001). Higher maternal age (> 35 years) has shown significantly higher anemic frequency at both high (57.89%; p < 0.002) and low (41.46%; p = 0.067) altitudes. A balanced-diet that is rich in meat products has also shown significant correlation with reduced incidences of anemia among pregnant women at both altitudes. Hemoglobin concentration increases in the body with elevated altitudes and, thus, anemia was less frequent at high-altitude region. Factors affecting hemoglobin concentration in full term pregnancy at different altitudes included old maternal age, low body-mass index, education and diet.

Evaluation of Hemoglobin Concentration in Pregnancy and Correlation with Different Altitude: A Study from Balochistan Plateau of Pakistan

PubMed Central

Umar, Zubaida; Rasool, Mahmood; Asif, Muhammad; Karim, Sajjad; Malik, Arif; Mushtaq, Gohar; Kamal, Mohammad A; Mansoor, Arsala

2015-01-01

Background: Anemia refers to a condition having low hemoglobin concentration. Anemia is considered a major risk factor for unfavorable pregnancy outcomes. This is the first study describing the pattern of hemoglobin concentration during pregnancy and its relationship to areas of high and low altitudes in Balochistan (the largest of Pakistan’s four provinces). The main objective of this study was to observe hemoglobin levels and prevalence of anemia among pregnant women living in the high or low altitude areas of Balochistan. Methods: A randomized survey was conducted and blood samples were collected from 132 healthy full term pregnant women subjects and 110 unmarried females. The subjects of the current study were selected from two different areas of Balochistan (Quetta and Uthal). Hemoglobin levels of the subjects were analyzed on Microlab 300 by Merck kit. Dietary status of the subjects was assessed based on simplified associated food frequency questionnaire. The factors effecting hemoglobin in full term pregnancy at different altitudes were multi gravidity/parity (increased number of pregnancies/children), age, socio-economic and educational status. Results: Anemia was highly prevalent in low-altitude region (68.33%). We found statistically significant difference in mean hemoglobin level at high-altitude region (11.81 ± 1.02) and low-altitude region (10.20 ± 1.28) in pregnant females of Balochistan plateau (P < 0.001). Higher maternal age (> 35 years) has shown significantly higher anemic frequency at both high (57.89%; p < 0.002) and low (41.46%; p = 0.067) altitudes. A balanced-diet that is rich in meat products has also shown significant correlation with reduced incidences of anemia among pregnant women at both altitudes. Conclusion: Hemoglobin concentration increases in the body with elevated altitudes and, thus, anemia was less frequent at high-altitude region. Factors affecting hemoglobin concentration in full term pregnancy at different altitudes included old maternal age, low body-mass index, education and diet. PMID:25741391

Adaptation to Life in the High Andes: Nocturnal Oxyhemoglobin Saturation in Early Development

PubMed Central

Hill, Catherine Mary; Baya, Ana; Gavlak, Johanna; Carroll, Annette; Heathcote, Kate; Dimitriou, Dagmara; L'Esperance, Veline; Webster, Rebecca; Holloway, John; Virues-Ortega, Javier; Kirkham, Fenella Jane; Bucks, Romola Starr; Hogan, Alexandra Marie

2016-01-01

Study Objectives: Physiological adaptation to high altitude hypoxia may be impaired in Andeans with significant European ancestry. The respiratory ‘burden’ of sleep may challenge adaptation, leading to relative nocturnal hypoxia. Developmental aspects of sleep-related breathing in high-altitude native children have not previously been reported. We aimed to determine the influence of development on diurnal-nocturnal oxyhemoglobin differences in children living at high altitude. Methods: This was a cross-sectional, observational study. Seventy-five healthy Bolivian children aged 6 mo to 17 y, native to low altitude (500 m), moderate high altitude (2,500 m), and high altitude (3,700 m) were recruited. Daytime resting pulse oximetry was compared to overnight recordings using Masimo radical oximeters. Genetic ancestry was determined from DNA samples. Results: Children had mixed European/Amerindian ancestry, with no significant differences between altitudes. Sixty-two participants had ≥ 5 h of nocturnal, artifact-free data. As predicted, diurnal mean oxyhemoglobin saturation decreased across altitudes (infants and children, both P < 0.001), with lowest diurnal values at high altitude in infants. At high altitude, there was a greater drop in nocturnal mean oxyhemoglobin saturation (infants, P < 0.001; children, P = 0.039) and an increase in variability (all P ≤ 0.001) compared to low altitude. Importantly, diurnal to nocturnal altitude differences diminished (P = 0.036), from infancy to childhood, with no further change during adolescence. Conclusions: Physiological adaptation to high-altitude living in native Andeans is unlikely to compensate for the significant differences we observed between diurnal and nocturnal oxyhemoglobin saturation, most marked in infancy. This vulnerability to sleep-related hypoxia in early childhood has potential lifespan implications. Future studies should characterize the sleep- related respiratory physiology underpinning our observations. Citation: Hill CM, Baya A, Gavlak J, Carroll A, Heathcote K, Dimitriou D, L'Esperance V, Webster R, Holloway J, Virues-Ortega J, Kirkham FJ, Bucks RS, Hogan AM. Adaptation to life in the high andes: nocturnal oxyhemoglobin saturation in early development. SLEEP 2016;39(5):1001–1008. PMID:26951394

[Quantitative apportionment of slope aspect and altitude to soil moisture and temperature and plant distribution on alpine meadow].

PubMed

Niu, Yu Jie; Zhou, Jian Wei; Yang, Si Wei; Wang, Gui Zhen; Liu, Li; Hua, Li Min

2017-05-18

For understanding the effect of aspect and altitude of hill on soil moisture and temperature as well as the vegetation community, we selected an alpine meadow located on a hill in north-eastern Tibet Plateau as our study area. Data on soil moisture and temperature, as well as plant distribution pattern in this mountain ecosystem were collected. We used regression analysis, CCA ordination and variance decomposition, to determine the impacts of the key factors (aspect, altitude, soil temperature and moisture) on plant diversity distribution in 189 sample sites of the hill. The results showed that the plant diversity of shady aspect and bottomland was highest and lowest, respectively. The plant diversity of the shady aspect and on the ridge of the hill increased initially and then decreased with the increasing altitude, but the plant diversity of the sunny aspect increased with the increasing altitude. At 0-30 cm soil layer, the soil temperature of the sunny aspect was higher than that of other aspects, but the soil temperature at 0-20 cm soil layer did not change with the increa-sing altitude. The soil moisture of shady aspect was higher than that of other aspects, and increased with the increasing altitude. The aspect and altitude explained 100% of soil temperature changes and 51.8% of soil moisture variation. Aspect alone explained 72.2% of soil temperature variation and altitude alone explained 51.8% of soil moisture variation, which had the highest contribution rate individually. Most plants were distributed on the shady aspect and on the ridge, and at medium altitude. Sedges mainly grew on the shady aspect, while Gramineae grew on the sunny aspect, the ridge was an ecotone. Cyperaceae, Gramineae and Leguminosae were mainly distributed in low altitude zone. Hill aspect and altitude totally explained 28.6% of plant abundance variation, hill aspect alone explained 19.9% of plant abundance variation. The management of grassland production and ecological restoration in alpine meadow ecosystem should consider the effect of landform on soil and vegetation, and the hill aspect should be priority factor instead of altitude when planning management interventions.

Variability of Martian Turbopause Altitudes

NASA Astrophysics Data System (ADS)

Slipski, Marek; Jakosky, Bruce; Benna, Mehdi; Mahaffy, Paul R.; Elrod, Meredith K.; Kass, David M.; Gonzalez-Galindo, Francisco

2017-10-01

The transition region between the well-mixed, turbulent lower atmosphere and the diffusive upper atmosphere - the turbopause - is an area of coupled physical processes that can have significant impacts on the structure and dynamics of the mesosphere and thermosphere. Above the turbopause, molecular diffusion dominates and species fractionate according to their masses. Below, turbulence is strong and waves dissipate and break. We have used density measurements from MAVEN's NGIMS instrument and temperatures from MRO's MCS to calculate turbopause altitudes over the course of a Martian year.The homopause, or "mixing-turbopause,” is defined with respect to the mixing ratio of a given atmospheric species. The mean molecular mass of the atmosphere remains essentially constant below, but each species has its own scale height above. We determined this altitude for each MAVEN orbit between Feb 2015 - Dec 2016 by extrapolating the ratio of N2 and 40Ar densities downward to where their ratio equals that measured by Curiosity. To determine the "wave-turbopause" (Offermann et al., 2007) we used variations in monthly-averaged temperature profiles of the upper and lower atmosphere. Because the dissipation of waves produces turbulence the turbopause altitude is set by the transition from strong to weak dissipation. If no energy were lost, the amplitude of a vertically propagating gravity wave would increase exponentially with altitude. Using the monthly standard deviation in temperatures as a proxy for wave amplitude, we show that waves are strongly dissipated at low altitudes but freely propagating in the lower thermosphere. The altitude at which the standard deviation begins to increase substantially from low values at mid-altitudes determines the altitude of the "wave-turbopause."The observed range of turbopause altitudes is 80-140 km. The turbopause is highest during the day and for Ls values near 270°. Homopause altitudes correlate well with changes in CO2 densities. The variation in turbopause altitudes means that energy, mass, and momentum transported vertically are deposited at different altitudes across the planet, which can have a substantial effect on the thermal and dynamical state of the middle-upper atmosphere.

Pituitary, gonadal and adrenal hormones after prolonged residence at extreme altitude in man.

PubMed

Basu, M; Pal, K; Prasad, R; Malhotra, A S; Rao, K S; Sawhney, R C

1997-06-01

High altitude-induced alterations in pituitary, gonadal and adrenal hormones were studied in (i) eugonadal men from the armed forces who were resident at sea level (SL), (ii) SL residents staying at an altitude of 3542 m for periods ranging from 3 to 12 months (acclimatized lowlanders, ALL), (iii) ALL who stayed at 6300 m for 6 months, (iv) ALL who trekked from 3542 to 5080 m and stayed at an altitude of more than 6300 m in the glacier region for 6 months, and (v) high-altitude natives (HAN) resident at an altitude of 3300-3700 m. Circulating levels of LH, FSH, prolactin, cortisol, testosterone, dihydrotestosterone (DHT) and progesterone in ALL at 3542 m and in HAN were not significantly different (p > 0.05) from the SL control values. When the ALL living at 3542 m trekked to an extreme altitude of 5080 m, their testosterone levels showed a significant decrease (p < 0.01) compared to the preceding altitude values but had returned to SL values when measured after 6 months' continuous stay at 6300 m. As with testosterone, the levels of DHT and oestradiol-17 beta (E2) after prolonged stay at extreme altitude were also not significantly different (p > 0.05) from the SL values. The LH levels after trekking to 5080 m were significantly higher (p < 0.01) than at an altitude of 3542 m, but decreased to levels found at 3542 m or SL after prolonged residence at extreme altitude. Plasma levels of ACTH, prolactin, FSH and cortisol on arrival at 5080 m, and after a 6-month stay at extreme altitude, were not significantly different (p > 0.05) from the SL values. Plasma progesterone levels tended to increase on arrival at 5080 m but a significant increase (p < 0.001) was evident only after a 6-month stay at extreme altitude. These observations suggest that prolonged residence at lower as well as at extreme altitude does not appreciably alter blood levels of pituitary, gonadal or adrenal hormones except for plasma levels of progesterone. The exact mechanism and significance of this increase remains unknown, but may be important in increasing the sensitivity of the hypoxic ventilatory response and activation of haemoglobin synthesis.

Cardiovascular autonomic modulation and activity of carotid baroreceptors at altitude.

PubMed

Bernardi, L; Passino, C; Spadacini, G; Calciati, A; Robergs, R; Greene, R; Martignoni, E; Anand, I; Appenzeller, O

1998-11-01

1. To assess the effects of acute exposure to high altitude on baroreceptor function in man we evaluated the effects of baroreceptor activation on R-R interval and blood pressure control at high altitude. We measured the low-frequency (LF) and high-frequency (HF) components in R-R, non-invasive blood pressure and skin blood flow, and the effect of baroreceptor modulation by 0. 1-Hz sinusoidal neck suction. Ten healthy sea-level natives and three high-altitude native, long-term sea-level residents were evaluated at sea level, upon arrival at 4970 m and 1 week later.2. Compared with sea level, acute high altitude decreased R-R and increased blood pressure in all subjects [sea-level natives: R-R from 1002+/-45 to 775+/-57 ms, systolic blood pressure from 130+/-3 to 150+/-8 mmHg; high-altitude natives: R-R from 809+/-116 to 749+/-47 ms, systolic blood pressure from 110+/-12 to 125+/-11 mmHg (P<0.05 for all)]. One week later systolic blood pressure was similar to values at sea level in all subjects, whereas R-R remained elevated in sea-level natives. The low-frequency power in R-R and systolic blood pressure increased in sea-level natives [R-R-LF from 47+/-8 to 65+/-10% (P<0.05), systolic blood pressure-LF from 1.7+/-0. 3 to 2.6+/-0.4 ln-mmHg2 (P<0.05)], but not in high-altitude natives (R-R-LF from 32+/-13 to 38+/-19%, systolic blood pressure-LF from 1. 9+/-0.5 to 1.7+/-0.8 ln-mmHg2). The R-R-HF decreased in sea-level natives but not in high-altitude natives, and no changes occurred in systolic blood pressure-HF. These changes remained evident 1 week later. Skin blood flow variability and its spectral components decreased markedly at high altitude in sea-level natives but showed no changes in high-altitude natives. Neck suction significantly increased the R-R- and systolic blood pressure-LF in all subjects at both sea level and high altitude.3. High altitude induces sympathetic activation in sea-level natives which is partially counteracted by active baroreflex. Despite long-term acclimatization at sea level, high-altitude natives also maintain active baroreflex at high altitude but with lower sympathetic activation, indicating a persisting high-altitude adaptation which may be genetic or due to baroreflex activity not completely lost by at least 1 year's sea-level residence.

Understanding controls on cirque floor altitudes: Insights from Kamchatka

NASA Astrophysics Data System (ADS)

Barr, Iestyn D.; Spagnolo, Matteo

2015-11-01

Glacial cirques reflect former regions of glacier initiation, and are therefore used as indicators of past climate. One specific way in which palaeoclimatic information is obtained from cirques is by analysing their elevations, on the assumption that cirque floor altitudes are a proxy for climatically controlled equilibrium-line altitudes (ELAs) during former periods of small scale (cirque-type) glaciation. However, specific controls on cirque altitudes are rarely assessed, and the validity of using cirque floor altitudes as a source of palaeoclimatic information remains open to question. In order to address this, here we analyse the distribution of 3520 ice-free cirques on the Kamchatka Peninsula (eastern Russia), and assess various controls on their floor altitudes. In addition, we analyse controls on the mid-altitudes of 503 modern glaciers, currently identifiable on the peninsula, and make comparisons with the cirque altitude data. The main study findings are that cirque floor altitudes increase steeply inland from the Pacific, suggesting that moisture availability (i.e., proximity to the coastline) played a key role in regulating the altitudes at which former (cirque-forming) glaciers were able to initiate. Other factors, such as latitude, aspect, topography, geology, and neo-tectonics seem to have played a limited (but not insignificant) role in regulating cirque floor altitudes, though south-facing cirques are typically higher than their north-facing equivalents, potentially reflecting the impact of prevailing wind directions (from the SSE) and/or variations in solar radiation on the altitudes at which former glaciers were able to initiate. Trends in glacier and cirque altitudes across the peninsula are typically comparable (i.e., values typically rise from both the north and south, inland from the Pacific coastline, and where glaciers/cirques are south-facing), yet the relationship with latitude is stronger for modern glaciers, and the relationship with distance to the coastline (and to a lesser degree with aspect) is notably weaker. These differences suggest that former glacier initiation (leading to cirque formation) was largely regulated by moisture availability (during winter months) and the control this exerted on accumulation; whilst the survival of modern glaciers is also strongly regulated by the variety of climatic and non-climatic factors that control ablation. As a result, relationships between modern glacier mid-altitudes and peninsula-wide climatic trends are more difficult to identify than when cirque floor altitudes are considered (i.e., cirque-forming glaciers were likely in climatic equilibrium, whereas modern glaciers may not be).

14 CFR 91.177 - Minimum altitudes for IFR operations.

Code of Federal Regulations, 2010 CFR

2010-01-01

..., an altitude of 2,000 feet above the highest obstacle within a horizontal distance of 4 nautical miles from the course to be flown; or (ii) In any other case, an altitude of 1,000 feet above the highest... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Minimum altitudes for IFR operations. 91...

14 CFR 91.177 - Minimum altitudes for IFR operations.

Code of Federal Regulations, 2011 CFR

2011-01-01

... mountainous area in part 95 of this chapter, an altitude of 2,000 feet above the highest obstacle within a... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Minimum altitudes for IFR operations. 91... Instrument Flight Rules § 91.177 Minimum altitudes for IFR operations. (a) Operation of aircraft at minimum...

How do you approach seizures in the high altitude traveler?

PubMed

Maa, Edward H

2011-01-01

Counseling patients who suffer first-time or break- through seizures can be difficult, particularly when controllable external factors may be contributing to the lowering of their seizure threshold. High altitude as a potential trigger for seizures is a common question in our epilepsy clinics in Colorado, and this article reviews the existing anecdotal literature, presents our local experience with high altitude seizures (HAS), offers possible mechanisms to explain how high altitude may trigger seizures, and suggests an initial work-up and prophylactic strategies for future high altitude exposures.

Accurate Modeling of Ionospheric Electromagnetic Fields Generated by a Low-Altitude VLF Transmitter

DTIC Science & Technology

2007-08-31

latitude) for 3 different grid spacings. 14 8. Low-altitude fields produced by a 10-kHz source computed using the FD and TD codes. The agreement is...excellent, validating the new FD code. 16 9. High-altitude fields produced by a 10-kHz source computed using the FD and TD codes. The agreement is...again excellent. 17 10. Low-altitude fields produced by a 20-k.Hz source computed using the FD and TD codes. 17 11. High-altitude fields produced

A quantitative analysis of TIMS data obtained on the Learjet 23 at various altitudes

NASA Technical Reports Server (NTRS)

Jaggi, S.

1992-01-01

A series of Thermal Infrared Multispectral Scanner (TIMS) data acquisition flights were conducted on the NASA Learjet 23 at different altitudes over a test site. The objective was to monitor the performance of the TIMS (its estimation of the brightness temperatures of the ground scene) with increasing altitude. The results do not show any significant correlation between the brightness temperatures and the altitude. The analysis indicates that the estimation of the temperatures is a function of the accuracy of the atmospheric correction used for each altitude.

Results from flight and simulator studies of a Mach 3 cruise longitudinal autopilot

NASA Technical Reports Server (NTRS)

Gilyard, G. B.; Smith, J. W.

1978-01-01

At Mach numbers of approximately 3.0 and altitudes greater than 21,300 meters, the original altitude and Mach hold modes of the YF-12 autopilot produced aircraft excursions that were erratic or divergent, or both. Flight data analysis and simulator studies showed that the sensitivity of the static pressure port to angle of attack had a detrimental effect on the performance of the altitude and Mach hold modes. Good altitude hold performance was obtained when a high passed pitch rate feedback was added to compensate for angle of attack sensitivity and the altitude error and integral altitude gains were reduced. Good Mach hold performance was obtained when the angle of attack sensitivity was removed; however, the ride qualities remained poor.

Mechanisms of Memory Dysfunction during High Altitude Hypoxia Training in Military Aircrew.

PubMed

Nation, Daniel A; Bondi, Mark W; Gayles, Ellis; Delis, Dean C

2017-01-01

Cognitive dysfunction from high altitude exposure is a major cause of civilian and military air disasters. Pilot training improves recognition of the early symptoms of altitude exposure so that countermeasures may be taken before loss of consciousness. Little is known regarding the nature of cognitive impairments manifesting within this critical window when life-saving measures may still be taken. Prior studies evaluating cognition during high altitude simulation have predominantly focused on measures of reaction time and other basic attention or motor processes. Memory encoding, retention, and retrieval represent critical cognitive functions that may be vulnerable to acute hypoxic/ischemic events and could play a major role in survival of air emergencies, yet these processes have not been studied in the context of high altitude simulation training. In a series of experiments, military aircrew underwent neuropsychological testing before, during, and after brief (15 min) exposure to high altitude simulation (20,000 ft) in a pressure-controlled chamber. Acute exposure to high altitude simulation caused rapid impairment in learning and memory with relative preservation of basic visual and auditory attention. Memory dysfunction was predominantly characterized by deficiencies in memory encoding, as memory for information learned during high altitude exposure did not improve after washout at sea level. Retrieval and retention of memories learned shortly before altitude exposure were also impaired, suggesting further impairment in memory retention. Deficits in memory encoding and retention are rapidly induced upon exposure to high altitude, an effect that could impact life-saving situational awareness and response. (JINS, 2017, 23, 1-10).

Update in the understanding of altitude-induced limitations to performance in team-sport athletes

PubMed Central

Billaut, François; Aughey, Robert J

2013-01-01

The internationalism of field-based team sports (TS) such as football and rugby requires teams to compete in tournaments held at low to moderate altitude (∼1200–2500 m). In TS, acceleration, speed and aerobic endurance are physical characteristics associated with ball possession and, ultimately, scoring. While these qualities are affected by the development of neuromuscular fatigue at sea level, arterial hypoxaemia induced by exposure to altitude may further hinder the capacity to perform consecutive accelerations (CAC) or sprint endurance and thereby change the outcome of a match. The higher the altitude, the more severe the hypoxaemia, and thus, the larger the expected decline in aerobic endurance, CAC and match running performance. Therefore, it is critical for athletes and coaches to understand how arterial hypoxaemia affects aerobic endurance and CAC and the magnitude of decline they may face at altitude for optimal preparation and increased chances of success. This mini review summarises the effects of acute altitude/hypoxia exposure on aerobic endurance, CAC and activity profiles of TS athletes performing in the laboratory and during matches at natural altitude, and analyses the latest findings about the consequences of arterial hypoxaemia on the relationship between peripheral perturbations, neural adjustments and performance during repeated sprints or CAC. Finally, we briefly discuss how altitude training can potentially help athletes prepare for competition at altitude. PMID:24282202

Update in the understanding of altitude-induced limitations to performance in team-sport athletes.

PubMed

Billaut, François; Aughey, Robert J

2013-12-01

The internationalism of field-based team sports (TS) such as football and rugby requires teams to compete in tournaments held at low to moderate altitude (∼1200-2500 m). In TS, acceleration, speed and aerobic endurance are physical characteristics associated with ball possession and, ultimately, scoring. While these qualities are affected by the development of neuromuscular fatigue at sea level, arterial hypoxaemia induced by exposure to altitude may further hinder the capacity to perform consecutive accelerations (CAC) or sprint endurance and thereby change the outcome of a match. The higher the altitude, the more severe the hypoxaemia, and thus, the larger the expected decline in aerobic endurance, CAC and match running performance. Therefore, it is critical for athletes and coaches to understand how arterial hypoxaemia affects aerobic endurance and CAC and the magnitude of decline they may face at altitude for optimal preparation and increased chances of success. This mini review summarises the effects of acute altitude/hypoxia exposure on aerobic endurance, CAC and activity profiles of TS athletes performing in the laboratory and during matches at natural altitude, and analyses the latest findings about the consequences of arterial hypoxaemia on the relationship between peripheral perturbations, neural adjustments and performance during repeated sprints or CAC. Finally, we briefly discuss how altitude training can potentially help athletes prepare for competition at altitude.

Improving estimation of flight altitude in wildlife telemetry studies

USGS Publications Warehouse

Poessel, Sharon; Duerr, Adam E.; Hall, Jonathan C.; Braham, Melissa A.; Katzner, Todd

2018-01-01

Altitude measurements from wildlife tracking devices, combined with elevation data, are commonly used to estimate the flight altitude of volant animals. However, these data often include measurement error. Understanding this error may improve estimation of flight altitude and benefit applied ecology.There are a number of different approaches that have been used to address this measurement error. These include filtering based on GPS data, filtering based on behaviour of the study species, and use of state-space models to correct measurement error. The effectiveness of these approaches is highly variable.Recent studies have based inference of flight altitude on misunderstandings about avian natural history and technical or analytical tools. In this Commentary, we discuss these misunderstandings and suggest alternative strategies both to resolve some of these issues and to improve estimation of flight altitude. These strategies also can be applied to other measures derived from telemetry data.Synthesis and applications. Our Commentary is intended to clarify and improve upon some of the assumptions made when estimating flight altitude and, more broadly, when using GPS telemetry data. We also suggest best practices for identifying flight behaviour, addressing GPS error, and using flight altitudes to estimate collision risk with anthropogenic structures. Addressing the issues we describe would help improve estimates of flight altitude and advance understanding of the treatment of error in wildlife telemetry studies.

Improvement in altitude performance test after further acclimatization in pre-acclimatized soldiers.

PubMed

Tannheimer, Markus; Buzzelli, Mark D; Albertini, Nadine; Lechner, Raimund; Ulmer, Hans-V; Engelhardt, Michael

2013-05-01

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 were all pre-acclimatized before arrival. The sleeping altitude remained constant at 11,060 ft, and the daytime altitudes increased up to a maximum of 15,775 ft. Test results improved significantly after a further 9 days of acclimatization (time, -11 s; SpO2, +5%-points; p ≤ 0.001). This is remarkable because all soldiers were pre-acclimatized and showed only minor acute mountain sickness symptoms during the entire stay. This indicates that the acclimatization process is not finished after amelioration of altitude symptoms. The demonstrated improvement in physical performance could prove very important, particularly during military missions performed at high altitude. Reprint & Copyright © 2013 Association of Military Surgeons of the U.S.

Elevated Suicide Rates at High Altitude: Sociodemographic and Health Issues May Be to Blame

ERIC Educational Resources Information Center

Betz, Marian E.; Valley, Morgan A.; Lowenstein, Steven R.; Hedegaard, Holly; Thomas, Deborah; Stallones, Lorann; Honigman, Benjamin

2011-01-01

Suicide rates are higher at high altitudes; some hypothesize that hypoxia is the cause. We examined 8,871 suicides recorded in 2006 in 15 states by the National Violent Death Reporting System, with the victim's home county altitude determined from the National Elevation Dataset through FIPS code matching. We grouped cases by altitude (low less…

Changes in intestinal microbiota across an altitudinal gradient in the lizard Phrynocephalus vlangalii.

PubMed

Zhang, Wenya; Li, Na; Tang, Xiaolong; Liu, Naifa; Zhao, Wei

2018-05-01

High altitude is an important driving force in animal evolution. However, the effect of altitude on gut microbial communities in reptiles has not been examined in detail. Here, we investigated the intestinal microbiota of three populations of the lizard Phrynocephalus vlangalii living at different altitudes using 16S rRNA gene sequencing. Bacteroidetes, Firmicutes, and Proteobacteria were the most abundant phyla. Bacteroides , Odoribacter , and Parabacteroides were the most abundant genera. Significant differences in the intestinal microbiota composition were found among the three populations from different altitudes. The proportions of Verrucomicrobia and Akkermansia decreased, whereas Bacteroides increased significantly with altitude. Greater abundance of Bacteroides at higher altitude led to the fractional increase in the phylum Bacteroides relative to other phyla. Hypoxia may be the main factor that caused intestinal microbiota variation in P. vlangalii along the altitude gradient. Overall, our study suggested that the community composition and structure of intestinal microbiota of the lizard P. vlangalii varied along altitudes, and such differences likely play a certain role in highland adaptation. Our findings warrant a further study that would determine whether ambient and body temperatures play a key role in the modulation of intestinal microbiota in reptiles.

Variability of Diurnal Temperature Range During Winter Over Western Himalaya: Range- and Altitude-Wise Study

NASA Astrophysics Data System (ADS)

Shekhar, M. S.; Devi, Usha; Dash, S. K.; Singh, G. P.; Singh, Amreek

2018-04-01

The current trends in diurnal temperature range, maximum temperature, minimum temperature, mean temperature, and sun shine hours over different ranges and altitudes of Western Himalaya during winter have been studied. Analysis of 25 years of data shows an increasing trend in diurnal temperature range over all the ranges and altitudes of Western Himalaya during winter, thereby confirming regional warming of the region due to present climate change and global warming. Statistical studies show significant increasing trend in maximum temperature over all the ranges and altitudes of Western Himalaya. Minimum temperature shows significant decreasing trend over Pir Panjal and Shamshawari range and significant increasing trend over higher altitude of Western Himalaya. Similarly, sunshine hours show significant decreasing trend over Karakoram range. There exists strong positive correlation between diurnal temperature range and maximum temperature for all the ranges and altitudes of Western Himalaya. Strong negative correlation exists between diurnal temperature range and minimum temperature over Shamshawari and Great Himalaya range and lower altitude of Western Himalaya. Sunshine hours show strong positive correlation with diurnal temperature range over Pir Panjal and Great Himalaya range and lower and higher altitudes.

Transcriptomic analysis provides insight into high-altitude acclimation in domestic goats.

PubMed

Tang, Qianzi; Huang, Wenyao; Guan, Jiuqiang; Jin, Long; Che, Tiandong; Fu, Yuhua; Hu, Yaodong; Tian, Shilin; Wang, Dawei; Jiang, Zhi; Li, Xuewei; Li, Mingzhou

2015-08-10

Domestic goats are distributed in a wide range of habitats and have acclimated to their local environmental conditions. To investigate the gene expression changes of goats that are induced by high altitude stress, we performed RNA-seq on 27 samples from the three hypoxia-sensitive tissues (heart, lung, and skeletal muscle) in three indigenous populations from distinct altitudes (600 m, 2000 m, and 3000 m). We generated 129Gb of high-quality sequencing data (~4Gb per sample) and catalogued the expression profiles of 12,421 annotated hircine genes in each sample. The analysis showed global similarities and differences of high-altitude transcriptomes among populations and tissues as well as revealed that the heart underwent the most high-altitude induced expression changes. We identified numerous differentially expressed genes that exhibited distinct expression patterns, and nonsynonymous single nucleotide variant-containing genes that were highly differentiated between the high- and low-altitude populations. These genes have known or potential roles in hypoxia response and were enriched in functional gene categories potentially responsible for high-altitude stress. Therefore, they are appealing candidates for further investigation of the gene expression and associated regulatory mechanisms related to high-altitude acclimation. Copyright © 2015 Elsevier B.V. All rights reserved.

Tracking performance with two breathing oxygen concentrations after high altitude rapid decompression

NASA Technical Reports Server (NTRS)

Nesthus, Thomas E.; Schiflett, Samuel G.; Oakley, Carolyn J.

1992-01-01

Current military aircraft Liquid Oxygen (LOX) systems supply 99.5 pct. gaseous Aviator's Breathing Oxygen (ABO) to aircrew. Newer Molecular Sieve Oxygen Generation Systems (MSOGS) supply breathing gas concentration of 93 to 95 pct. O2. The margin is compared of hypoxia protection afforded by ABO and MSOGS breathing gas after a 5 psi differential rapid decompression (RD) in a hypobaric research chamber. The barometric pressures equivalent to the altitudes of 46000, 52000, 56000, and 60000 ft were achieved from respective base altitudes in 1 to 1.5 s decompressions. During each exposure, subjects remained at the simulated peak altitude breathing either 100 or 94 pct. O2 with positive pressure for 60 s, followed by a rapid descent to 40000 ft. Subjects used the Tactical Life Support System (TLSS) for high altitude protection. Subcritical tracking task performance on the Performance Evaluation Device (PED) provided psychomotor test measures. Overall tracking task performance results showed no differences between the MSOGS breathing O2 concentration of 94 pct. and ABO. Significance RMS error differences were found between the ground level and base altitude trials compared to peak altitude trials. The high positive breathing pressures occurring at the peak altitudes explained the differences.

DLR HABLEG- High Altitude Balloon Launched Experimental Glider

NASA Astrophysics Data System (ADS)

Wlach, S.; Schwarzbauch, M.; Laiacker, M.

2015-09-01

The group Flying Robots at the DLR Institute of Robotics and Mechatronics in Oberpfaffenhofen conducts research on solar powered high altitude aircrafts. Due to the high altitude and the almost infinite mission duration, these platforms are also denoted as High Altitude Pseudo-Satellites (HAPS). This paper highlights some aspects of the design, building, integration and testing of a flying experimental platform for high altitudes. This unmanned aircraft, with a wingspan of 3 m and a mass of less than 10 kg, is meant to be launched as a glider from a high altitude balloon in 20 km altitude and shall investigate technologies for future large HAPS platforms. The aerodynamic requirements for high altitude flight included the development of a launch method allowing for a safe transition to horizontal flight from free-fall with low control authority. Due to the harsh environmental conditions in the stratosphere, the integration of electronic components in the airframe is a major effort. For regulatory reasons a reliable and situation dependent flight termination system had to be implemented. In May 2015 a flight campaign was conducted. The mission was a full success demonstrating that stratospheric research flights are feasible with rather small aircrafts.

The British Services Dhaulagiri Medical Research Expedition 2016: a unique military and civilian research collaboration.

PubMed

Mellor, Adrian; Bakker-Dyos, J; Howard, M; Boos, C; Cooke, M; Vincent, E; Scott, P; O'Hara, J; Clarke, S B; Barlow, M; Matu, J; Deighton, K; Hill, N; Newman, C; Cruttenden, R; Holdsworth, D; Woods, D

2017-12-01

High-altitude environments lead to a significant physiological challenge and disease processes which can be life threatening; operational effectiveness at high altitude can be severely compromised. The UK military research is investigating ways of mitigating the physiological effects of high altitude. The British Service Dhaulagiri Research Expedition took place from March to May 2016, and the military personnel were invited to consent to a variety of study protocols investigating adaptation to high altitudes and diagnosis of high-altitude illness. The studies took place in remote and austere environments at altitudes of up to 7500 m. This paper gives an overview of the individual research protocols investigated, the execution of the expedition and the challenges involved. 129 servicemen and women were involved at altitudes of up to 7500 m; 8 research protocols were investigated. The outputs from these studies will help to individualise the acclimatisation process and inform strategies for pre-acclimatisation should troops ever need to deploy at high altitude at short notice. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

High-altitude medical and operations problems and solutions for the Millimeter Array

NASA Astrophysics Data System (ADS)

Napier, Peter J.; West, John B.

1998-07-01

The 5000m altitude of the potential site for the Millimeter Array (MMA) in Northern Chile is so high that high-altitude problems for both the staff and equipment must be considered and included in planing for the facility. The very good accessibility of the site, only one hour's drive from the nearest town at altitude 2440m, makes it possible for MMA workers to sleep and perform much of their work at low altitude. Workers on the site will have 11 percent less oxygen available than workers at Mauna Kea Observatory. It is expected that the mental abilities and ability to do hard physical labor of workers on the high site will be reduced by 10 percent to 30 percent compared to sea-level. In-doors working areas on the MMA site will have their atmospheres oxygen enriched to provide an effective working altitude of 3500m where loss of mental ability should be small. Tests of oxygen enrichment at high-altitude Chilean mines and at the University of California White Mountain Research Station show that it is feasible and economic. Problems of equipment operation at 5000m altitude are expected to be manageable.

High altitude-related hypertensive crisis and acute kidney injury in an asymptomatic healthy individual.

PubMed

Gilbert-Kawai, Edward; Martin, Daniel; Grocott, Michael; Levett, Denny

2016-01-01

High-altitude exposure causes a mild to moderate rise in systolic and diastolic blood pressure. This case report describes the first documented case of a hypertensive crisis at altitude, as well as the first report of the occurrence of acute kidney injury in the context of altitude-related hypertension. A healthy, previously normotensive 30-year old, embarked on a trek to Everest Base Camp (5300 m). During his 11-day ascent the subject developed increasingly worsening hypertension. In the absence of symptoms, the individual initially elected to remain at altitude as had previously been the plan. However, an increase in the severity of his hypertension to a peak of 223/119 mmHg resulted in a decision to descend. On descent he was found to have an acute kidney injury that subsequently resolved spontaneously. His blood pressure reverted to normal at sea level and subsequent investigations including a transthoracic echocardiogram, cardiac magnetic resonance imaging, renal ultrasound, and urinary catecholamines were normal. This report challenges the view that transient rises in blood pressure at altitude are without immediate risk. We review the evidence that altitude induces hypertension and discuss the implications for the management of hypertension at altitude.

Airplane Measurements of Atmospheric Turbulence at Altitudes Between 20,000 and 55,000 Feet for Four Geographic Areas

NASA Technical Reports Server (NTRS)

Coleman, Thomas L.; Meadows, May T.

1959-01-01

Measurements of clear-air turbulence by use of airplane-borne instruments have been obtained from NACA VGH recorders during research flights of Lockheed U-2 airplanes at altitudes between 20,000 and 55,000 feet over Western United States, England and Western Europe, Turkey, and Japan. An analysis of these data has indicated that at the higher altitudes (40,000 to 55,000 feet) turbulence is both less frequent and less severe than at the lower altitudes (20,000 to 40,000 feet). Turbulence appears to be encountered at the high altitudes for only about 2 percent of the flight distance as compared with 5 percent or more at the lower altitudes. Moderately heavy turbulence exists on occasion at altitudes of about 50,000 feet over Japan and appears to be associated with the strong character of the jet stream in this area and also with a mountain-wave phenomenon.

Extreme Pregnancy: Maternal Physical Activity at Everest Base Camp.

PubMed

Davenport, Margie H; Steinback, Craig D; Borle, Kennedy J; Matenchuk, Brittany A; Vanden Berg, Emily R; de Freitas, Emily M; Linares, Andrea M; O'Halloran, Ken D; Sherpa, Mingma T; Day, Trevor A

2018-05-10

High altitude natives employ numerous physiological strategies to survive and reproduce. However, the concomitant influence of altitude and physical activity during pregnancy has not been studied above 3,700m. We report a case of physical activity, sleep behavior and physiological measurements on a 28-year-old third-trimester pregnant native highlander (Sherpa) during ascent from 3440m to Everest base camp (~5,300m) over eight days in the Nepal Himalaya, and again ~10-months postpartum during a similar ascent profile. The participant engaged in 250-300 minutes of moderate-to-vigorous physical activity (MVPA) per day during ascent to altitude while pregnant, with similar volumes of MVPA while postpartum. There were no apparent maternal, fetal or neonatal complications related to the superimposition of the large volumes of physical activity at altitude. This report demonstrates a rare description of physical activity and ascent to high altitude during pregnancy and points to novel questions regarding the superimposition of pregnancy, altitude and physical activity in high altitude natives.

Hemopoiesis in the pig-tailed monkey Macaca nemestrina during chronic altitude exposure.

NASA Technical Reports Server (NTRS)

Buderer, M. C.; Pace, N.

1972-01-01

Study of monkeys for 180 days at 3800 m altitude to examine their hemopoietic response. Plasma volume was found to be reduced while red cell volume increased steadily for four to five months. Reduction in mean corpuscular hemoglobin content was observed from day 30 to day 120 at altitude. Total plasma protein concentration was unchanged at altitude, but marked reduction in the albumin/globulin ratio occurred. Total circulating plasma protein and albumin were reduced in amount, whereas nonalbumin protein was unchanged. These results imply loss of albumin coupled with a corresponding loss of water from the blood and maintenance of normal plasma osmotic pressure. The body/venous hematocrit ratio was found to be reduced at altitude, possibly as a consequence of the expanded capillary volume of the body. The hemopoietic responses of the pig-tailed monkey at altitude require at least several months for completion, and closely resemble those seen in man; thus, the monkey can serve well for long-term studies of high-altitude acclimatization.

CAT altitude avoidance system

NASA Technical Reports Server (NTRS)

Gary, B. L. (Inventor)

1982-01-01

A method and apparatus are provided for indicating the altitude of the tropopause or of an inversion layer wherein clear air turbulence (CAT) may occur, and the likely severity of any such CAT, includes directing a passive microwave radiometer on the aircraft at different angles with respect to the horizon. The microwave radiation measured at a frequency of about 55 GHz represents the temperature of the air at an ""average'' range of about 3 kilometers, so that the sine of the angle of the radiometer times 3 kilometers equals the approximate altitude of the air whose temperature is measured. A plot of altitude (with respect to the aircraft) versus temperature of the air at that altitude, can indicate when an inversion layer is present and can indicate the altitude of the tropopause or of such an inversion layer. The plot can also indicate the severity of any CAT in an inversion layer. If CAT has been detected in the general area, then the aircraft can be flown at an altitude to avoid the tropopause or inversion layer.

The risk of cardiovascular events during leisure time activities at altitude.

PubMed

Burtscher, Martin; Ponchia, Andrea

2010-01-01

Annually, more than 100 million tourists are attracted by the mountainous areas around the world. On the one hand, leisure time activities at altitude may well contribute to the well-established beneficial effects of exercise; on the other hand, these activities are also associated with a relatively high risk of death. Sudden cardiac death (SCD) is the most frequent cause of nontraumatic death in males older than 34 years at altitude during leisure time activities such as downhill skiing and hiking. Whereas prior myocardial infarction is the most important risk factor for SCD, particularly relevant in downhill skiers, the unusual physical activity during the first days at altitude and the prolonged abstinence from food and fluid intake during exercise at altitude are the most important triggers. Unaccustomed physical activity seems more likely to trigger SCD than altitude per se. The detection of subjects at risk, evidence-based therapy, and advice on adequate behavior during the altitude sojourn will help to prevent SCD and to increase the health benefits generated by mountaineering activities.

Fluid-electrolyte shifts and maximal oxygen uptake in man at simulated altitude /2,287 m/

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Bernauer, E. M.; Adams, W. C.; Juhos, L.

1978-01-01

Experiments were conducted on six trained distance runners (21-23 yr) subjected to an eight-day dietary control at sea level, followed by an eight-day stay in an altitude chamber (2287-m altitude) and a four-day recovery at sea level. Fluid and electrolyte shifts during exercise at altitude were evaluated to gain insight into the mechanism of reduction in working capacity. The results are discussed in terms of resting fluid volumes and blood constituents, maximal exercise variables, and maximal exercise fluid-electrolyte shifts. Since there are no significant changes in fluid balance or resting plasma volume (PV) at altitude, it is concluded that neither these nor the excessive PV shifts with exercise contribute to the reduction in maximal oxygen uptake at altitude. During altitude exposure the percent loss in PV is found to follow the percent reduction in maximal oxygen uptake; however, on the first day of recovery the percent change in PV remains depressed while maximal oxygen uptake returns to control levels.

Evidence for helical kink instability in the Venus magnetic flux ropes

NASA Technical Reports Server (NTRS)

Elphic, R. C.; Russell, C. T.

1983-01-01

Empirical models of the magnetic field structure of flux ropes found in the Venus ionosphere are seen as suggesting that the ropes are unstable to long-wavelength (more than 100 km) helical-kink perturbations. The onset of such an instability can explain the apparent volume distribution of flux ropes with altitude, as well as their orientation as a function of altitude. In the subsolar region, the fraction of volume occupied by flux ropes increases from approximately 20 percent at high altitudes to more than 50 percent at low altitudes; this is a greater increase than would be expected if ropes convect downward as simple straight horizontal cylinders. The helical kink instability raises the fractional volume occupied by ropes by turning the originally straight, horizontal flux tubes into corkscrew-shaped structures as they convect to lower altitudes. It is noted that this instability also explains why high altitude ropes tend to be horizontal and low altitude ropes appear to have almost any orientation.

Comparison of Rocket Performance using Exhaust Diffuser and Conventional Techniques for Altitude Simulation

NASA Technical Reports Server (NTRS)

Sivo, Joseph N.; Peters, Daniel J.

1959-01-01

A rocket engine with an exhaust-nozzle area ratio of 25 was operated at a constant chamber pressure of 600 pounds per square inch absolute over a range of oxidant-fuel ratios at an altitude pressure corresponding to approximately 47,000 feet. At this condition, the nozzle flow is slightly underexpanded as it leaves the nozzle. The altitude simulation was obtained first through the use of an exhaust diffuser coupled with the rocket engine and secondly, in an altitude test chamber where separate exhauster equipment provided the altitude pressure. A comparison of performance data from these two tests has established that a diffuser used with a rocket engine operating at near-design nozzle pressure ratio can be a valid means of obtaining altitude performance data for rocket engines.

Physiological implications of altitude training for endurance performance at sea level: a review.

PubMed Central

Bailey, D M; Davies, B

1997-01-01

Acclimatisation to environmental hypoxia initiates a series of metabolic and musculocardio-respiratory adaptations that influence oxygen transport and utilisation, or better still, being born and raised at altitude, is necessary to achieve optimal physical performance at altitude, scientific evidence to support the potentiating effects after return to sea level is at present equivocal. Despite this, elite athletes continue to spend considerable time and resources training at altitude, misled by subjective coaching opinion and the inconclusive findings of a large number of uncontrolled studies. Scientific investigation has focused on the optimisation of the theoretically beneficial aspects of altitude acclimatisation, which include increases in blood haemoglobin concentration, elevated buffering capacity, and improvements in the structural and biochemical properties of skeletal muscle. However, not all aspects of altitude acclimatisation are beneficial; cardiac output and blood flow to skeletal muscles decrease, and preliminary evidence has shown that hypoxia in itself is responsible for a depression of immune function and increased tissue damage mediated by oxidative stress. Future research needs to focus on these less beneficial aspects of altitude training, the implications of which pose a threat to both the fitness and the health of the elite competitor. Paul Bert was the first investigator to show that acclimatisation to a chronically reduced inspiratory partial pressure of oxygen (P1O2) invoked a series of central and peripheral adaptations that served to maintain adequate tissue oxygenation in healthy skeletal muscle, physiological adaptations that have been subsequently implicated in the improvement in exercise performance during altitude acclimatisation. However, it was not until half a century later that scientists suggested that the additive stimulus of environmental hypoxia could potentially compound the normal physiological adaptations to endurance training and accelerate performance improvements after return to sea level. This has stimulated an exponential increase in scientific research, and, since 1984, 22 major reviews have summarised the physiological implications of altitude training for both aerobic and anaerobic performance at altitude and after return to sea level. Of these reviews, only eight have specifically focused on physical performance changes after return to sea level, the most comprehensive of which was recently written by Wolski et al. Few reviews have considered the potentially less favourable physiological responses to moderate altitude exposure, which include decreases in absolute training intensity, decreased plasma volume, depression of haemopoiesis and increased haemolysis, increases in sympathetically mediated glycogen depletion at altitude, and increased respiratory muscle work after return to sea level. In addition, there is a risk of developing more serious medical complications at altitude, which include acute mountain sickness, pulmonary oedema, cardiac arrhythmias, and cerebral hypoxia. The possible implications of changes in immune function at altitude have also been largely ignored, despite accumulating evidence of hypoxia mediated immunosuppression. In general, altitude training has been shown to improve performance at altitude, whereas no unequivocal evidence exists to support the claim that performance at sea level is improved. Table 1 summarises the theoretical advantages and disadvantages of altitude training for sea level performance. This review summarises the physiological rationale for altitude training as a means of enhancing endurance performance after return to sea level. Factors that have been shown to affect the acclimatisation process and the subsequent implications for exercise performance at sea level will also be discussed. Studies were located using five major database searches, which included Medline, Embase, Science Citation Index, Sports Discus, and Sport, in Images Figure 1 Figure 2 PMID:9298550

The effect of intermediate altitude on the Army Physical Fitness Test.

PubMed

Perry, M E; Browning, R J; Jackson, R; Meyer, J

1992-10-01

Official physical training records of personnel stationed at intermediate altitude (elevation 5,280 feet) for at least 1 year were reviewed to gauge the effect of altitude on 2-mile running performance. An average of 48 additional seconds (a 5% increase in time) was required to complete the run compared to sea-level values in the same subjects. Run times gradually diminished during the first 9 months of assignment to altitude before stability was established. These data indicate that acclimatization occurs over several months. Even with acclimatization, substantial loss of performance is associated with habitation at intermediate altitude.

Altitude Performance Characteristics of Tail-pipe Burner with Variable-area Exhaust Nozzle

NASA Technical Reports Server (NTRS)

Jansen, Emmert T; Thorman, H Carl

1950-01-01

An investigation was conducted in the NACA Lewis altitude wind tunnel to determine effect of altitude and flight Mach number on performance of tail-pipe burner equipped with variable-area exhaust nozzle and installed on full-scale turbojet engine. At a given flight Mach number, with constant exhaust-gas and turbine-outlet temperatures, increasing altitude lowered the tail-pipe combustion efficiency and raised the specific fuel consumption while the augmented thrust ratio remained approximately constant. At a given altitude, increasing flight Mach number raised the combustion efficiency and augmented thrust ratio and lowered the specific fuel consumption.

APOLLO 16 COMMANDER JOHN YOUNG ENTERS ALTITUDE CHAMBER FOR TESTS

NASA Technical Reports Server (NTRS)

1971-01-01

Apollo 16 commander John W. Young prepares to enter the lunar module in an altitude chamber in the Manned Spacecraft Operations Building at the spaceport prior to an altitude run. During the altitude run, in which Apollo 16 lunar module pilot Charles M. Duke also participated, the chamber was pumped down to simulate pressure at an altitude in excess of 200,000 feet. Young, Duke and command module pilot Thomas K. Mattingly II, are training at the Kennedy Space Center for the Apollo 16 mission. Launch is scheduled from Pad 39A, March 17, 1972.

CO2 non-LTE limb emissions in Mars' atmosphere as observed by OMEGA/Mars Express

NASA Astrophysics Data System (ADS)

Piccialli, A.; López-Valverde, M. A.; Määttänen, A.; González-Galindo, F.; Audouard, J.; Altieri, F.; Forget, F.; Drossart, P.; Gondet, B.; Bibring, J. P.

2016-06-01

We report on daytime limb observations of Mars upper atmosphere acquired by the OMEGA instrument on board the European spacecraft Mars Express. The strong emission observed at 4.3 μm is interpreted as due to CO2 fluorescence of solar radiation and is detected at a tangent altitude in between 60 and 110 km. The main value of OMEGA observations is that they provide simultaneously spectral information and good spatial sampling of the CO2 emission. In this study we analyzed 98 dayside limb observations spanning over more than 3 Martian years, with a very good latitudinal and longitudinal coverage. Thanks to the precise altitude sounding capabilities of OMEGA, we extracted vertical profiles of the non-local thermodynamic equilibrium (non-LTE) emission at each wavelength and we studied their dependence on several geophysical parameters, such as the solar illumination and the tangent altitude. The dependence of the non-LTE emission on solar zenith angle and altitude follows a similar behavior to that predicted by the non-LTE model. According to our non-LTE model, the tangent altitude of the peak of the CO2 emission varies with the thermal structure, but the pressure level where the peak of the emission is found remains constant at ˜0.03 ± 0.01 Pa, . This non-LTE model prediction has been corroborated by comparing SPICAM and OMEGA observations. We have shown that the seasonal variations of the altitude of constant pressure levels in SPICAM stellar occultation retrievals correlate well with the variations of the OMEGA peak emission altitudes, although the exact pressure level cannot be defined with the spectroscopy for the investigation of the characteristics of the atmosphere of Venus (SPICAM) nighttime data. Thus, observed changes in the altitude of the peak emission provide us information on the altitude of the 0.03 Pa pressure level. Since the pressure at a given altitude is dictated by the thermal structure below, the tangent altitude of the peak emission represents then an important piece of information of the atmosphere, of great value for validating general circulation models. We thus compared the altitude of OMEGA peak emission with the altitude of the 0.03 Pa level predicted by the Laboratoire de météorologie dynamique (LMD)-Mars global circulation model and found that the peak emission altitudes from OMEGA present a much larger variability than the tangent altitude of the 0.03 Pa level predicted by the general circulation model. This variability could be possibly due to unresolved atmospheric waves. Further studies using this strong CO2 limb emission data are proposed.

High-Altitude Illness

MedlinePlus

... after you travel. Make sure you pack enough water while you are active. Avoid or limit the amount of alcohol you consume. High-altitude illness treatment It is important to treat high-altitude illness ...

Ear - blocked at high altitudes

MedlinePlus

... ears; Flying and blocked ears; Eustachian tube dysfunction - high altitude ... to the eardrum) and the back of the nose and upper throat. ... down from high altitudes. Chewing gum the entire time you are ...

Operation Everest II. Altitude Decompression Sickness during Repeated Altitude Exposure,

DTIC Science & Technology

1986-05-01

Bends, Altitude, Hypobaric Chamber ILrJ " . .. . . " --" . .. " * .- . - - ’,, 3 INTRODUCTION Altitude Decompression Sickness (ADS) is a well...recognized and serious consequence of exposure to hypobaric conditions. It has been described during and after aircraft as well as hypobaric chamber flights...was noted in investigators during a recent study of chronic progressive hypoxia in a hypobaric chamber entitled Operation Everest II. The observations

Altitude Scaling of Thermal Ice Protection Systems in Running Wet Operation

NASA Technical Reports Server (NTRS)

Orchard, D. M.; Addy, H. E.; Wright, W. B.; Tsao, J.

2017-01-01

A study into the effects of altitude on an aircraft thermal Ice Protection System (IPS) performance has been conducted by the National Research Council Canada (NRC) in collaboration with the NASA Glenn Icing Branch. The study included tests of an airfoil model, with a heated-air IPS, installed in the NRCs Altitude Icing Wind Tunnel (AIWT) at altitude and ground level conditions.

Stunting and the Prediction of Lung Volumes Among Tibetan Children and Adolescents at High Altitude

PubMed Central

Garruto, Ralph M.

2015-01-01

Abstract Weitz, Charles A., and Ralph M. Garruto. Stunting and the prediction of lung volumes among Tibetan children and adolescents at high altitude. High Alt Biol Med 16:306–317, 2015.—This study examines the extent to which stunting (height-for-age Z-scores ≤ −2) compromises the use of low altitude prediction equations to gauge the general increase in lung volumes during growth among high altitude populations. The forced vital capacity (FVC) and forced expiratory volume (FEV1) of 208 stunted and 365 non-stunted high-altitude Tibetan children and adolescents between the ages of 6 and 20 years are predicted using the Third National Health and Nutrition Examination Survey (NHANESIII) and the Global Lung Function Initiative (GLF) equations, and compared to observed lung volumes. Stunted Tibetan children show smaller positive deviations from both NHANESIII and GLF prediction equations at most ages than non-stunted children. Deviations from predictions do not correspond to differences in body proportions (sitting heights and chest circumferences relative to stature) between stunted and non-stunted children; but appear compatible with the effects of retarded growth and lung maturation that are likely to exist among stunted children. These results indicate that, before low altitude standards can be used to evaluate the effects of hypoxia, or before high altitude populations can be compared to any other group, it is necessary to assess the relative proportion of stunted children in the samples. If the proportion of stunted children in a high altitude population differs significantly from the proportion in the comparison group, lung function comparisons are unlikely to yield an accurate assessment of the hypoxia effect. The best solution to this problem is to (1) use stature and lung function standards based on the same low altitude population; and (2) assess the hypoxic effect by comparing observed and predicted values among high altitude children whose statures are most like those of children on whom the low altitude spirometric standard is based—preferably high altitude children with HAZ-scores ≥ −1. PMID:26397381

High Altitude Is an Independent Risk Factor for Postoperative Symptomatic Venous Thromboembolism After Knee Arthroscopy: A Matched Case-Control Study of Medicare Patients.

PubMed

Cancienne, Jourdan M; Diduch, David R; Werner, Brian C

2017-02-01

To use a national database of Medicare patients to evaluate the association of uncomplicated knee arthroscopy performed at high altitude with the incidence of postoperative venous thromboembolism (VTE). The 100% Medicare Standard Analytical File database was queried for all patients undergoing isolated arthroscopic partial meniscectomy and/or chondroplasty from 2005-2012. Patients with more complex open or additional arthroscopic knee procedures, a personal history of VTE, or any hypercoagulable state were excluded. The result of this query was then stratified by the altitude of the hospital ZIP code in which the procedure was performed. The appropriate patients were placed into a high-altitude group (≥4,000 ft) and matched to patients who underwent the same procedures at an altitude less than or equal to 100 ft on the basis of age, sex, and medical comorbidities. The rate of VTE was then assessed for both the high-altitude and matched low-altitude patients within 30 days and 90 days postoperatively. The rate of combined VTE (deep venous thrombosis [DVT] and/or pulmonary embolism [PE]) (odds ratio [OR], 2.0; P = .0003), the rate of PE (OR, 2.5; P = .0099), and the rate of DVT (OR, 1.7; P = .0066) within 30 days were all significantly higher in patients with procedures performed at high altitude compared with matched patients with the same procedures performed at low altitude. At 90 days postoperatively, similarly elevated risks of VTE, PE, and DVT were found in patients with procedures performed at high altitude. In this study of knee arthroscopy in Medicare patients, a procedure performed at an altitude ≥4,000 ft was a significant risk factor for the development of postoperative VTE compared with matched patients undergoing the same procedure at an altitude less than or equal to 100 ft. Level III, retrospective case-control study. Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Effect of egg composition and oxidoreductase on adaptation of Tibetan chicken to high altitude.

PubMed

Jia, C L; He, L J; Li, P C; Liu, H Y; Wei, Z H

2016-07-01

Tibetan chickens have good adaptation to hypoxic conditions, which can be reflected by higher hatchability than lowland breeds when incubated at high altitude. The objective of this trial was to study changes in egg composition and metabolism with regards the adaptation of Tibetan chickens to high altitude. We measured the dry weight of chicken embryos, egg yolk, and egg albumen, and the activity of lactate dehydrogenase (LDH) and succinic dehydrogenase (SDH) in breast muscle, heart, and liver from embryos of Tibetan chicken and Dwarf chicken (lowland breed) incubated at high (2,900 m) and low (100 m) altitude. We found that growth of chicken embryos was restricted at high altitude, especially for Dwarf chicken embryos. In Tibetan chicken, the egg weight was lighter, but the dry weight of egg yolk was heavier than that of Dwarf chicken. The LDH activities of the three tissues from the high altitude groups were respectively higher than those of the lowland groups from d 15 to hatching, except for breast muscle of Tibetan chicken embryos on d 15. In addition, under the high altitude environment, the heart tissue from Tibetan chicken had lower LDH activity than that from Dwarf chicken at d 15 and 18. The lactic acid content of blood from Tibetan chicken embryos was lower than that of Dwarf chicken at d 12 and 15 of incubation at high altitude. There was no difference in SDH activity in the three tissues between the high altitude groups and the lowland groups except in three tissues of hatchlings and at d 15 of incubation in breast muscle, nor between the two breeds at high altitude except in the heart of hatchlings. Consequently, the adaptation of Tibetan chicken to high altitude may be associated with higher quantities of yolk in the egg and a low metabolic oxygen demand in tissue, which illuminate the reasons that the Tibetan chicken have higher hatchability with lower oxygen transport ability. © 2016 Poultry Science Association Inc.

Bicarbonate Values for Healthy Residents Living in Cities Above 1500 Meters of Altitude: A Theoretical Model and Systematic Review.

PubMed

Ramirez-Sandoval, Juan C; Castilla-Peón, Maria F; Gotés-Palazuelos, José; Vázquez-García, Juan C; Wagner, Michael P; Merelo-Arias, Carlos A; Vega-Vega, Olynka; Rincón-Pedrero, Rodolfo; Correa-Rotter, Ricardo

2016-06-01

Ramirez-Sandoval, Juan C., Maria F. Castilla-Peón, José Gotés-Palazuelos, Juan C. Vázquez-García, Michael P. Wagner, Carlos A. Merelo-Arias, Olynka Vega-Vega, Rodolfo Rincón-Pedrero, and Ricardo Correa-Rotter. Bicarbonate values for healthy residents living in cities above 1500 m of altitude: a theoretical model and systematic review. High Alt Med Biol. 17:85-92, 2016.-Plasma bicarbonate (HCO3(-)) concentration is the main value used to assess the metabolic component of the acid-base status. There is limited information regarding plasma HCO3(-) values adjusted for altitude for people living in cities at high altitude defined as 1500 m (4921 ft) or more above sea level. Our aim was to estimate the plasma HCO3(-) concentration in residents of cities at these altitudes using a theoretical model and compare these values with HCO3(-) values found on a systematic review, and with those venous CO2 values obtained in a sample of 633 healthy individuals living at an altitude of 2240 m (7350 ft). We calculated the PCO2 using linear regression models and calculated plasma HCO3(-) according to the Henderson-Hasselbalch equation. Results show that HCO3(-) concentration falls as the altitude of the cities increase. For each 1000 m of altitude above sea level, HCO3(-) decreases to 0.55 and 1.5 mEq/L in subjects living at sea level with acute exposure to altitude and in subjects acclimatized to altitude, respectively. Estimated HCO3(-) values from the theoretical model were not different to HCO3(-) values found in publications of a systematic review or with venous total CO2 measurements in our sample. Altitude has to be taken into consideration in the calculation of HCO3(-) concentrations in cities above 1500 m to avoid an overdiagnosis of acid-base disorders in a given individual.

Stunting and the Prediction of Lung Volumes Among Tibetan Children and Adolescents at High Altitude.

PubMed

Weitz, Charles A; Garruto, Ralph M

2015-12-01

This study examines the extent to which stunting (height-for-age Z-scores ≤ -2) compromises the use of low altitude prediction equations to gauge the general increase in lung volumes during growth among high altitude populations. The forced vital capacity (FVC) and forced expiratory volume (FEV1) of 208 stunted and 365 non-stunted high-altitude Tibetan children and adolescents between the ages of 6 and 20 years are predicted using the Third National Health and Nutrition Examination Survey (NHANESIII) and the Global Lung Function Initiative (GLF) equations, and compared to observed lung volumes. Stunted Tibetan children show smaller positive deviations from both NHANESIII and GLF prediction equations at most ages than non-stunted children. Deviations from predictions do not correspond to differences in body proportions (sitting heights and chest circumferences relative to stature) between stunted and non-stunted children; but appear compatible with the effects of retarded growth and lung maturation that are likely to exist among stunted children. These results indicate that, before low altitude standards can be used to evaluate the effects of hypoxia, or before high altitude populations can be compared to any other group, it is necessary to assess the relative proportion of stunted children in the samples. If the proportion of stunted children in a high altitude population differs significantly from the proportion in the comparison group, lung function comparisons are unlikely to yield an accurate assessment of the hypoxia effect. The best solution to this problem is to (1) use stature and lung function standards based on the same low altitude population; and (2) assess the hypoxic effect by comparing observed and predicted values among high altitude children whose statures are most like those of children on whom the low altitude spirometric standard is based-preferably high altitude children with HAZ-scores ≥ -1.

Experimental exposure of rats to methylene chloride at varying controlled barometric altitudes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lillquist, D.R.

1990-01-01

This study investigated combined effects of three methylene chloride (MC) volume/volume concentrations (0,50, and 500 ppm) at three controlled barometric altitudes (760, 640, and 560 torr). This provided a three by three study design. For each scenario, three altitude acclimated (6 days) adult male rats were studied for eight hours in a nose-only inhalation chamber. Blood (0.35 mL) was drawn from the cannulated left carotid artery of each rat at 0, 0.5, 1, 2, 4, and 8 hours and hematocrit, pO[sub 2], pCO[sub 2], pH , total hemoglobin (Hb) and carboxyhemoglobin (CHb) were measured. Time, MC concentration and altitude hadmore » significant effects on CHb production. CHb increased with increasing MC concentration over time. Increased barometric altitude (reduced partial pressure of MC vapor at altitude for equal ppm concentrations) resulted in lower blood CHb levels. A statistical model was derived to explain variation in CHb levels for these three independent variables (r = 0.983). The data were applied to an equation assessing the impact of altitude, MC concentration and time on the potential oxygen carrying capacity (POCC) of blood. The POCC of HB in the blood was calculated using blood Hb, CHb levels, Hb oxygen saturation (based on the blood pO[sub 2] and the oxygen dissociation curve for rats), and oxygen binding potential of Hb. It was determined for the altitudes and MC concentrations used, polycythemia associated with increased altitude had a greater impact on POCC than decreased pO[sub 2]. A regression equation was derived modeling variation in POCC of blood for the three independent variables (r = 0.995). This study demonstrated that altitude affects airborne ppm MC concentrations. This ultimately impacts CHb levels and oxygen carrying capacity of the blood. These finding indicate that occupationally acceptable ppm MC exposure levels at altitude do need barometric pressure correction.« less

The Effects of Altitude Training on Erythropoietic Response and Hematological Variables in Adult Athletes: A Narrative Review

PubMed Central

Płoszczyca, Kamila; Langfort, Józef; Czuba, Miłosz

2018-01-01

Background: One of the goals of altitude training is to increase blood oxygen-carrying capacity in order to improve sea-level endurance performance in athletes. The elevated erythropoietin (EPO) production in hypoxia is a key factor in the achievement of enhanced hematological variables. The level of the EPO increase and acceleration of erythropoiesis depend on the duration of exposure and degree of hypoxia. Furthermore, many other factors may affect the hematological response to altitude training. Aim: The purpose of this narrative review was to: (1) analyze the kinetics of EPO and hematological variables during and after altitude training; (2) summarize the current state of knowledge about the possible causes of individual or cohort differences in EPO and hematological response to altitude training; (3) formulate practical guidelines for athletes to improve the efficiency of altitude training. Methods: A narrative review was performed following an electronic search of the databases PubMed/MEDLINE and SPORTDiscus via EBSCO for all English-language articles published between 1997 and 2017. Results: Complete unification of results from studies on EPO kinetics was difficult due to different time and frequency of blood sampling by different researchers during and after altitude training, but the data presented in the reviewed literature allowed us to detect certain trends. The results of the reviewed studies were divergent and indicated either increase or no change of hematological variables following altitude training. Factors that may affect the hematological response to altitude training include hypoxic dose, training content, training background of athletes, and/or individual variability of EPO production. Conclusions: Despite the potential benefits arising from altitude training, its effectiveness in improving hematological variables is still debatable. Further research and better understanding of factors influencing the response to altitude, as well as factors affecting the suitable measurement and interpretation of study results, are needed. PMID:29695978

Free and total thyroid hormones in humans at extreme altitude

NASA Astrophysics Data System (ADS)

Basu, Minakshi; Pal, K.; Malhotra, A. S.; Prasad, R.; Sawhney, R. C.

1995-03-01

Alterations in circulatory levels of total T4 (TT4), total T3 (TT3), free T4 (FT4), free T3 (FT3), thyrotropin (TSH) and T3 uptake (T3U) were studied in male and female sea-level residents (SLR) at sea level, in Armed forces personnel staying at high altitude (3750 m) for prolonged duration (acclimatized lowlanders, ALL) and in high-altitude natives (HAN). Identical studies were also performed on male ALL who trekked to an extreme altitude of 5080 m and stayed at an altitude of more than 6300 m for about 6 months. The total as well as free thyroid hormones were found to be significantly higher in ALL and HAN as compared to SLR values. Both male as well as female HAN had higher levels of thyroid hormones. The rise in hormone levels in different ALL ethnic groups drawn from amongst the southern and northern parts of the country was more or less identical. In both HAN and ALL a decline in FT3 and FT4 occurred when these subjects trekked at subzero temperatures to extreme altitude of 5080 m but the levels were found to be higher in ALL who stayed at 6300 m for a prolonged duration. Plasma TSH did not show any appreciable change at lower altitudes but was found to be decreased at extreme altitude. The increase in thyroid hormones at high altitude was not due to an increase in hormone binding proteins, since T3U was found to be higher at high altitudes. A decline in TSH and hormone binding proteins and an increase in the free moiety of the hormones is indicative of a subtle degree of tissue hyperthyroidism which may be playing an important role in combating the extreme cold and hypoxic environment of high altitudes.

Evaluating the Risks of High Altitude Travel in Chronic Liver Disease Patients.

PubMed

Luks, Andrew M; Swenson, Erik R

2015-06-01

Luks, Andrew M., and Erik R. Swenson. Clinician's Corner: Evaluating the risks of high altitude travel in chronic liver disease patients. High Alt Med Biol 16:80-88, 2015.--With improvements in the quality of health care, people with chronic medical conditions are experiencing better quality of life and increasingly participating in a wider array of activities, including travel to high altitude. Whenever people with chronic diseases travel to this environment, it is important to consider whether the physiologic responses to hypobaric hypoxia will interact with the underlying medical condition such that the risk of acute altitude illness is increased or the medical condition itself may worsen. This review considers these questions as they pertain to patients with chronic liver disease. While the limited available evidence suggests there is no evidence of liver injury or dysfunction in normal individuals traveling as high as 5000 m, there is reason to suspect that two groups of cirrhosis patients are at increased risk for problems, hepatopulmonary syndrome patients, who are at risk for severe hypoxemia following ascent, and portopulmonary hypertension patients who may be at risk for high altitude pulmonary edema and acute right ventricular dysfunction. While liver transplant patients may tolerate high altitude exposure without difficulty, no information is available regarding the risks of long-term residence at altitude with chronic liver disease. All travelers with cirrhosis require careful pre-travel evaluation to identify conditions that might predispose to problems at altitude and develop risk mitigation strategies for these issues. Patients also require detailed counseling about recognition, prevention, and treatment of acute altitude illness and may require different medication regimens to prevent or treat altitude illness than used in healthy individuals.

Serious altitude illness in travelers who visited a pre-travel clinic.

PubMed

Croughs, Mieke; Van Gompel, Alfons; Rameckers, Sarah; Van den Ende, Jef

2014-01-01

Few data are available on the incidence and predictors of serious altitude illness in travelers who visit pre-travel clinics. Travel health consultants advise on measures to be taken in case of serious altitude illness but it is not clear if travelers adhere to these recommendations. Visitors to six travel clinics who planned to travel to an altitude of ≥3,000 m were asked to complete a diary from the first day at 2,000 m until 3 days after reaching the maximum sleeping altitude. Serious altitude illness was defined as having symptoms of serious acute mountain sickness (AMS score ≥ 6) and/or cerebral edema and/or pulmonary edema. The incidence of serious altitude illness in the 401 included participants of whom 90% reached ≥4,000 m, was 35%; 23% had symptoms of serious AMS, 25% symptoms of cerebral edema, and 13% symptoms of pulmonary edema. Independent predictors were young age, the occurrence of dark urine, travel in South America or Africa, and lack of acclimatization between 1,000 and 2,500 m. Acetazolamide was brought along by 77% of the responders of whom 41% took at least one dose. Of those with serious altitude illness, 57% had taken at least one dose of acetazolamide, 20% descended below 2,500 m on the same day or the next, and 11% consulted a physician. Serious altitude illness was a very frequent problem in travelers who visited pre-travel clinics. Young age, dark urine, travel in South America or Africa, and lack of acclimatization nights at moderate altitude were independent predictors. Furthermore, we found that seriously ill travelers seldom followed the advice to descend and to visit a physician. © 2014 International Society of Travel Medicine.

High altitude medicine education in China: exploring a new medical education reform.

PubMed

Luo, Yongjun; Luo, Rong; Li, Weiming; Huang, Jianjun; Zhou, Qiquan; Gao, Yuqi

2012-03-01

China has the largest plateau in the world, which includes the whole of Tibet, part of Qinghai, Xinjiang, Yunnan, and Sichuan. The plateau area is about 257.2×10(4) km(2), which accounts for about 26.8% of the total area of China. According to data collected in 2006, approximately twelve million people were living at high altitudes, between 2200 to 5200 m high, on the Qinghai-Tibetan Plateau. Therefore, there is a need for medical workers who are trained to treat individuals living at high altitudes. To train undergraduates in high altitude medicine, the College of High Altitude Military Medicine was set up at the Third Military Medical University (TMMU) in Chongqing in 1999. This is the only school to teach high altitude medicine in China. Students at TMMU study natural and social sciences, basic medical sciences, clinical medical sciences, and high altitude medicine. In their 5(th) year, students work as interns at the General Hospital of Tibet Military Command in Lhasa for 3 months, where they receive on-site teaching. The method of on-site teaching is an innovative approach for training in high altitude medicine for undergraduates. Three improvements were implemented during the on-site teaching component of the training program: (1) standardization of the learning progress; (2) integration of formal knowledge with clinical experience; and (3) coaching students to develop habits of inquiry and to engage in ongoing self-improvement to set the stage for lifelong learning. Since the establishment of the innovative training methods in 2001, six classes of high altitude medicine undergraduates, who received on-site teaching, have graduated and achieved encouraging results. This evidence shows that on-site teaching needs to be used more widely in high altitude medicine education.

Impact of extreme exercise at high altitude on oxidative stress in humans

PubMed Central

Dumke, Charles; Slivka, Dustin; Ruby, Brent

2015-01-01

Abstract Exercise and oxidative stress research continues to grow as a physiological subdiscipline. The influence of high altitude on exercise and oxidative stress is among the recent topics of intense study in this area. Early findings indicate that exercise at high altitude has an independent influence on free radical generation and the resultant oxidative stress. This review provides a detailed summary of oxidative stress biochemistry as gleaned mainly from studies of humans exercising at high altitude. Understanding of the human response to exercise at altitude is largely derived from field‐based research at altitudes above 3000 m in addition to laboratory studies which employ normobaric hypoxia. The implications of oxidative stress incurred during high altitude exercise appear to be a transient increase in oxidative damage followed by redox‐sensitive adaptations in multiple tissues. These outcomes are consistent for lowland natives, high altitude acclimated sojourners and highland natives, although the latter group exhibits a more robust adaptive response. To date there is no evidence that altitude‐induced oxidative stress is deleterious to normal training or recovery scenarios. Limited evidence suggests that deleterious outcomes related to oxidative stress are limited to instances where individuals are exposed to extreme elevations for extended durations. However, confirmation of this tentative conclusion requires further investigation. More applicably, altitude‐induced hypoxia may have an independent influence on redox‐sensitive adaptive responses to exercise and exercise recovery. If correct, these findings may hold important implications for athletes, mountaineers, and soldiers working at high altitude. These points are raised within the confines of published research on the topic of oxidative stress during exercise at altitude. PMID:26453842

Effects of hiking at moderate and low altitude on cardiovascular parameters in male patients with metabolic syndrome: Austrian Moderate Altitude Study.

PubMed

Neumayr, Günther; Fries, Dietmar; Mittermayer, Markus; Humpeler, Egon; Klingler, Anton; Schobersberger, Wolfgang; Spiesberger, Reinhard; Pokan, Rochus; Schmid, Peter; Berent, Robert

2014-09-01

Physical activity is a cornerstone in therapy for patients with metabolic syndrome. Walking and hiking in a mountain scenery represents an ideal approach to make them move. The Austrian Moderate Altitude Study (AMAS) 2000 main study is a randomized controlled trial to investigate the cardiovascular effects of hiking at moderate altitude on patients with metabolic syndrome compared with a control group at low altitude, to assess a potential altitude-specific effect. Seventy-one male patients with metabolic syndrome were randomly assigned to a moderate altitude group (at 1700 m), with 36 participants, or to a low altitude group (at 200 m), with 35 participants. The 3-week vacation program included 12 hiking tours (4 per week, average duration 2.5 hours, intensity 55% to 65% of heart rate maximum). Physical parameters, performance capacity, 24-hour blood pressure, and heart rate profiles were obtained before, during, and after the stay. In both groups, we found a significant mean weight loss of -3.13 kg; changes in performance capacity were minor. Systolic, diastolic, and mean arterial pressures and circadian heart rate profiles were significantly reduced in both groups, with no differences between them. Consequently, the pressure-rate product was reduced as well. All study participants tolerated the vacation well without any adverse events. A 3-week hiking vacation at moderate or low altitude is safe for patients with metabolic syndrome and provides several improvements in their cardiovascular parameters. The cardiovascular benefits achieved are more likely to be the result of regular physical activity than the altitude-specific effect of a mountain environment. Copyright © 2014 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

Can patients with coronary heart disease go to high altitude?

PubMed

Dehnert, Christoph; Bärtsch, Peter

2010-01-01

Tourism to high altitude is very popular and includes elderly people with both manifest and subclinical coronary heart disease (CHD). Thus, risk assessment regarding high altitude exposure of patients with CHD is of increasing interest, and individual recommendations are expected despite the lack of sufficient scientific evidence. The major factor increasing cardiac stress is hypoxia. At rest and for a given external workload, myocardial oxygen demand is increased at altitude, particularly in nonacclimatized individuals, and there is some evidence that blood-flow reserve is reduced in atherosclerotic coronary arteries even in the absence of severe stenosis. Despite a possible imbalance between oxygen demand and oxygen delivery, studies on selected patients have shown that exposure and exercise at altitudes of 3000 to 3500 m is generally safe for patients with stable CHD and sufficient work capacity. During the first days at altitude, patients with stable angina may develop symptoms of myocardial ischemia at slightly lower heart rate x  blood-pressure products. Adverse cardiac events, however, such as unstable angina coronary syndromes, do not occur more frequently compared with sea level except for those who are unaccustomed to exercise. Therefore, training should start before going to altitude, and the altitude-related decrease in exercise capacity should be considered. Travel to 3500 m should be avoided unless patients have stable disease, preserved left ventricular function without residual capacity, and above-normal exercise capacity. CHD patients should avoid travel to elevations above 4500 m owing to severe hypoxia at these altitudes. The risk assessment of CHD patients at altitude should always consider a possible absence of medical support and that cardiovascular events may turn into disaster.

A new parameterization of the UV irradiance altitude dependence for clear-sky conditions and its application in the on-line UV tool over Northern Eurasia

NASA Astrophysics Data System (ADS)

Chubarova, Nataly; Zhdanova, Yekaterina; Nezval, Yelena

2016-09-01

A new method for calculating the altitude UV dependence is proposed for different types of biologically active UV radiation (erythemally weighted, vitamin-D-weighted and cataract-weighted types). We show that for the specified groups of parameters the altitude UV amplification (AUV) can be presented as a composite of independent contributions of UV amplification from different factors within a wide range of their changes with mean uncertainty of 1 % and standard deviation of 3 % compared with the exact model simulations with the same input parameters. The parameterization takes into account for the altitude dependence of molecular number density, ozone content, aerosol and spatial surface albedo. We also provide generalized altitude dependencies of the parameters for evaluating the AUV. The resulting comparison of the altitude UV effects using the proposed method shows a good agreement with the accurate 8-stream DISORT model simulations with correlation coefficient r > 0.996. A satisfactory agreement was also obtained with the experimental UV data in mountain regions. Using this parameterization we analyzed the role of different geophysical parameters in UV variations with altitude. The decrease in molecular number density, especially at high altitudes, and the increase in surface albedo play the most significant role in the UV growth. Typical aerosol and ozone altitude UV effects do not exceed 10-20 %. Using the proposed parameterization implemented in the on-line UV tool (http://momsu.ru/uv/) for Northern Eurasia over the PEEX domain we analyzed the altitude UV increase and its possible effects on human health considering different skin types and various open body fraction for January and April conditions in the Alpine region.

Heart rate variabilty changes during first week of acclimatization to 3500 m altitude in Indian military personnel.

PubMed

Bhaumik, G; Dass, D; Bhattacharyya, D; Sharma, Y K; Singh, S B

2013-01-01

Acute exposure to hypobaric hypoxia induces the changes in autonomic control of heart rate. Due to emergencies or war like conditions, rapid deployment of Indian military personnel into high altitude frequently occurs. Rapid deployment to high altitude soldiers are at risk of developing high altitude sickness. The present study was conducted to evaluate the acute exposure to high altitude hypobaric hypoxia (3500 m altitude) on the autonomic nervous control of heart rate in Indian military personnel during first week of acclimatization Indices of heart rate variability (viz; R-R interval, total power, low frequency, high frequency, ratio of low to high frequency) and pulse arterial oxygen saturation were measured at sea level and 3500m altitude. Power spectrum of heart rate variability was quantified by low frequency (LF: 0.04-0.15 Hz) and high frequency (HF: 0.15-0.5 Hz) widths. The ratio of LF to HF was also assessed as an index of the sympathovagal balance. Mean R-R interval decreased significantly on day 2 on induction to altitude which tended to increase on day 5. Total power (TP) decreased high altitude and tended to recover within a week. Both HF and LF power showed decrement at 3500m in comparison to sea level. The ratio of LF to HF (LF/HF) at 3500m was significantly higher at 3500m. SpO2 values decreased significantly (P < 0.05) at high altitude on day-2 which increased on day-5. We conclude that autonomic control of the heart rate measured by heart rate variability was altered on acute induction to 3500m which showed a significant decrease in parasympathetic tone and increase in sympathetic tone, then acclimatization seems to be characterized by progressive shift toward a higher parasympathetic tone.

Analysis of High-Altitude De-Acclimatization Syndrome after Exposure to High Altitudes: A Cluster-Randomized Controlled Trial

PubMed Central

Hu, Mingdong; Qu, Xinming; Wei, Zhenghua; Li, Jin; Chen, Yan; Chen, Huaping; Zhou, Qiquan; Wang, Guansong

2013-01-01

The syndrome of high-altitude de-acclimatization commonly takes place after long-term exposure to high altitudes upon return to low altitudes. The syndrome severely affects the returnee's quality of life. However, little attention has been paid to careful characterization of the syndrome and their underlying mechanisms. Male subjects from Chongqing (n = 67, 180 m) and Kunming (n = 70, 1800 m) visited a high-altitude area (3650 m) about 6 months and then returned to low-altitude. After they came back, all subjects were evaluated for high-altitude de-acclimatization syndrome on the 3rd, 50th, and 100th. Symptom scores, routine blood and blood gas tests, and myocardial zymograms assay were used for observation their syndrome. The results showed that the incidence and severity of symptoms had decreased markedly on the 50th and 100th days, compared with the 3rd day. The symptom scores and incidence of different symptoms were lower among subjects returning to Kunming than among those returning to Chongqing. On the 3rd day, RBC, Hb, Hct, CK, CK-MB, and LDH values were significantly lower than values recorded at high altitudes, but they were higher than baseline values. On the 50th day, these values were not different from baseline values, but LDH levels did not return to baseline until the 100th day. These data show that, subjects who suffered high-altitude de-acclimatization syndrome, the recovery fully processes takes a long time (≥100th days). The appearance of the syndrome is found to be related to the changes in RBC, Hb, Hct, CK, CK-MB, and LDH levels, which should be caused by reoxygenation after hypoxia. PMID:23650508

[Possibilities of the pharmacological correction of adaptive reactions of human organism in short-term moving from middle to high altitude].

PubMed

Kundashev, U K; Zurdinov, A Z; Barchukov, V G

2014-01-01

It was assessed the efficacy of drugs belonging to the class of actoprotectors and antihypoxants, which are prescribed for short-term adaptation of the human organism moving from middle altitude (1670 m) to high altitude (3750 m). Volunteers stayed at the middle altitude for 15 days before moving to the high altitude. Prior to climbing, upon arrival at high altitude, and on the 3rd day, the state of the CNS, cardiovascular system, red and white blood growth, and some indices of the energy exchange metabolism were assessed. Drugs or placebo were administered in tablets after the first testing (one hour before moving to high altitude), upon arrival at altitude (next day, after breakfast), and on the third day (one hour before last testing). It is established that a combination of metaprote and ladasten (in doses of 0.125 and 0.1 g, respectively) favors acceleration of the short-term adaptation, which is manifested by the improved tolerance of physical activity at high altitude and the acceleration of white and red blood growth. In case of the combined administration of both actoprotectors, the adaptive reactions of tolerance and blood system were more pronounced in comparison to the administration of hypoxen (0.5 g) alone. A distinguishing feature of the reaction of the human organism upon taking the combination of actoprotectors was that adaptation of the energy supply system (judging from metabolites studied) already took place in the first hours of staying at high altitudes, while the adaptation upon taking 0.5 g hypoxen was observed on the 3rd day and the adaptive reactions in placebo group were still developing on the 3rd day.

Analysis of high-altitude de-acclimatization syndrome after exposure to high altitudes: a cluster-randomized controlled trial.

PubMed

He, Binfeng; Wang, Jianchun; Qian, Guisheng; Hu, Mingdong; Qu, Xinming; Wei, Zhenghua; Li, Jin; Chen, Yan; Chen, Huaping; Zhou, Qiquan; Wang, Guansong

2013-01-01

The syndrome of high-altitude de-acclimatization commonly takes place after long-term exposure to high altitudes upon return to low altitudes. The syndrome severely affects the returnee's quality of life. However, little attention has been paid to careful characterization of the syndrome and their underlying mechanisms. Male subjects from Chongqing (n = 67, 180 m) and Kunming (n = 70, 1800 m) visited a high-altitude area (3650 m) about 6 months and then returned to low-altitude. After they came back, all subjects were evaluated for high-altitude de-acclimatization syndrome on the 3(rd), 50(th), and 100(th). Symptom scores, routine blood and blood gas tests, and myocardial zymograms assay were used for observation their syndrome. The results showed that the incidence and severity of symptoms had decreased markedly on the 50(th) and 100(th) days, compared with the 3(rd) day. The symptom scores and incidence of different symptoms were lower among subjects returning to Kunming than among those returning to Chongqing. On the 3(rd) day, RBC, Hb, Hct, CK, CK-MB, and LDH values were significantly lower than values recorded at high altitudes, but they were higher than baseline values. On the 50(th) day, these values were not different from baseline values, but LDH levels did not return to baseline until the 100(th) day. These data show that, subjects who suffered high-altitude de-acclimatization syndrome, the recovery fully processes takes a long time (≥ 100(th) days). The appearance of the syndrome is found to be related to the changes in RBC, Hb, Hct, CK, CK-MB, and LDH levels, which should be caused by reoxygenation after hypoxia.

Sleeping altitude and sudden cardiac death.

PubMed

Lo, Monica Y; Daniels, James D; Levine, Benjamin D; Burtscher, Martin

2013-07-01

Mountain activities characterized by strenuous exercise in a hypoxic setting place unique demands on the body. The mortality rate associated with mountain activities is high, with sudden cardiac death (SCD) representing the most frequent of all nontraumatic deaths. We evaluated the possible effect of acclimatization in reduction of SCD during high-altitude sojourns. This was a retrospective cohort study involving all deaths (N = 559) that occurred during mountain activities in Austria from 1985 through 1993. Baseline patient demographics, cardiovascular comorbidities, smoking history, family history of SCD, sleeping altitude, annual mountaineering frequency, and physical activity on the day of SCD were included in a questionnaire previously used in a pilot study. Data from 301 of 599 individuals without prespecified exclusions were available for analysis (79% of eligible cohort). Sudden cardiac deaths happened mostly around noon (29%), and mean altitude at which SCDs occurred was 1,710 ± 501 m. When sleeping altitude was divided into quartiles (<700 m, 700-999 m, 1,000-1,299 m, and >1,299 m), the odds ratio for SCD on the first day at altitude when sleeping below 700 m was 5.7 (95% CI 2.8-11.6) as compared with sleeping above 1,299 m. For males >34 years, those with history of coronary artery disease and/or prior infarction, and those unaccustomed to physical activity at altitude, sleeping at moderate altitude before exercising at altitude may reduce the risk of SCD. Copyright © 2013 Mosby, Inc. All rights reserved.

Soil Organic Carbon Pool and Its Chemical Composition in Phyllostachy pubescens Forests at Two Altitudes in Jian-ou City, China.

PubMed

Ji, Haibao; Zhuang, Shunyao; Zhu, Zhaoliang; Zhong, Zheke

2015-01-01

Phyllostachys pubescens forests play an important role in soil organic carbon (SOC) sequestration in terrestrial ecosystems. However, the estimation and mechanism of SOC sequestration by P. pubescens forests remain unclear. In this study, the effect of P. pubescens forest distribution with elevation was investigated at two altitude sites in Jian-ou City, Southeast China. SOC storage was estimated and its chemical composition was obtained via 13C-nuclear magnetic resonance (NMR), chemical classification, and spectral analysis. Results showed that the SOC contents and stocks were significantly higher at the high-altitude site than at the low-altitude site in the entire soil profile (0-60 cm). The C contents of the three combined humus forms exhibited similar responses to the elevation change, and all of these forms were higher at the high-altitude site than at the low-altitude site regardless of soil layer. However, the proportions of the three combined humus C showed no significant differences between the two altitudes. The results of 13C-NMR showed that the SOC chemical composition did not significantly vary with elevation as well. This finding was consistent with the E465/E665 of the loosely combined humus. Overall, the results suggested that altitude should be considered during regional SOC estimation and that altitude affected the quantity rather than the quality of the SOC under the same P. pubescens vegetation.

Soil Organic Carbon Pool and Its Chemical Composition in Phyllostachy pubescens Forests at Two Altitudes in Jian-ou City, China

PubMed Central

Ji, Haibao; Zhuang, Shunyao; Zhu, Zhaoliang; Zhong, Zheke

2015-01-01

Phyllostachys pubescens forests play an important role in soil organic carbon (SOC) sequestration in terrestrial ecosystems. However, the estimation and mechanism of SOC sequestration by P. pubescens forests remain unclear. In this study, the effect of P. pubescens forest distribution with elevation was investigated at two altitude sites in Jian-ou City, Southeast China. SOC storage was estimated and its chemical composition was obtained via 13C-nuclear magnetic resonance (NMR), chemical classification, and spectral analysis. Results showed that the SOC contents and stocks were significantly higher at the high-altitude site than at the low-altitude site in the entire soil profile (0–60 cm). The C contents of the three combined humus forms exhibited similar responses to the elevation change, and all of these forms were higher at the high-altitude site than at the low-altitude site regardless of soil layer. However, the proportions of the three combined humus C showed no significant differences between the two altitudes. The results of 13C-NMR showed that the SOC chemical composition did not significantly vary with elevation as well. This finding was consistent with the E465/E665 of the loosely combined humus. Overall, the results suggested that altitude should be considered during regional SOC estimation and that altitude affected the quantity rather than the quality of the SOC under the same P. pubescens vegetation. PMID:26716688

Metabolic characteristics and response to high altitude in Phrynocephalus erythrurus (Lacertilia: Agamidae), a lizard dwell at altitudes higher than any other living lizards in the world.

PubMed

Tang, Xiaolong; Xin, Ying; Wang, Huihui; Li, Weixin; Zhang, Yang; Liang, Shiwei; He, Jianzheng; Wang, Ningbo; Ma, Ming; Chen, Qiang

2013-01-01

Metabolic response to high altitude remains poorly explored in reptiles. In the present study, the metabolic characteristics of Phrynocephaluserythrurus (Lacertilia: Agamidae), which inhabits high altitudes (4500 m) and Phrynocephalusprzewalskii (Lacertilia: Agamidae), which inhabits low altitudes, were analysed to explore the metabolic regulatory strategies for lizards living at high-altitude environments. The results indicated that the mitochondrial respiratory rates of P. erythrurus were significantly lower than those of P. przewalskii, and that proton leak accounts for 74~79% of state 4 and 7~8% of state3 in P. erythrurus vs. 43~48% of state 4 and 24~26% of state3 in P. przewalskii. Lactate dehydrogenase (LDH) activity in P. erythrurus was lower than in P. przewalskii, indicating that at high altitude the former does not, relatively, have a greater reliance on anaerobic metabolism. A higher activity related to β-hydroxyacyl coenzyme A dehydrogenase (HOAD) and the HOAD/citrate synthase (CS) ratio suggested there was a possible higher utilization of fat in P. erythrurus. The lower expression of PGC-1α and PPAR-γ in P. erythrurus suggested their expression was not influenced by cold and low PO2 at high altitude. These distinct characteristics of P. erythrurus are considered to be necessary strategies in metabolic regulation for living at high altitude and may effectively compensate for the negative influence of cold and low PO2.

Metabolic Characteristics and Response to High Altitude in Phrynocephalus erythrurus (Lacertilia: Agamidae), a Lizard Dwell at Altitudes Higher Than Any Other Living Lizards in the World

PubMed Central

Tang, Xiaolong; Xin, Ying; Wang, Huihui; Li, Weixin; Zhang, Yang; Liang, Shiwei; He, Jianzheng; Wang, Ningbo; Ma, Ming; Chen, Qiang

2013-01-01

Metabolic response to high altitude remains poorly explored in reptiles. In the present study, the metabolic characteristics of Phrynocephalus erythrurus (Lacertilia: Agamidae), which inhabits high altitudes (4500 m) and Phrynocephalus przewalskii (Lacertilia: Agamidae), which inhabits low altitudes, were analysed to explore the metabolic regulatory strategies for lizards living at high-altitude environments. The results indicated that the mitochondrial respiratory rates of P . erythrurus were significantly lower than those of P . przewalskii , and that proton leak accounts for 74~79% of state 4 and 7~8% of state3 in P . erythrurus vs. 43~48% of state 4 and 24~26% of state3 in P . przewalskii . Lactate dehydrogenase (LDH) activity in P . erythrurus was lower than in P . przewalskii , indicating that at high altitude the former does not, relatively, have a greater reliance on anaerobic metabolism. A higher activity related to β-hydroxyacyl coenzyme A dehydrogenase (HOAD) and the HOAD/citrate synthase (CS) ratio suggested there was a possible higher utilization of fat in P . erythrurus . The lower expression of PGC-1α and PPAR-γ in P . erythrurus suggested their expression was not influenced by cold and low PO2 at high altitude. These distinct characteristics of P . erythrurus are considered to be necessary strategies in metabolic regulation for living at high altitude and may effectively compensate for the negative influence of cold and low PO2. PMID:23951275

Effect of altitude on biochemical composition and quality of green arabica coffee beans can be affected by shade and postharvest processing method.

PubMed

Worku, Mohammed; de Meulenaer, Bruno; Duchateau, Luc; Boeckx, Pascal

2018-03-01

Although various studies have assessed altitude, shade and postharvest processing effects on biochemical content and quality of coffee beans, data on their interactions are scarce. The individual and interactive effects of these factors on the caffeine, chlorogenic acids (CGA) and sucrose contents as well as physical and sensory qualities of green coffee beans from large plantations in southwestern Ethiopia were evaluated. Caffeine and CGA contents decreased with increasing altitude; they respectively declined 0.12 and 1.23gkg -1 100m -1 . Sucrose content increased with altitude; however, the altitude effect was significant for wet-processed beans (3.02gkg -1 100m -1 ), but not for dry-processed beans (0.36g kg -1 100m -1 ). Similarly, sucrose content increased with altitude with much stronger effect for coffee grown without shade (2.11gkg -1 100m -1 ) compared to coffee grown under shade (0.93gkg -1 100m -1 ). Acidity increased with altitude when coffee was grown under shade (0.22 points 100m -1 ), but no significant altitude effect was observed on coffee grown without shade. Beans grown without shade showed a higher physical quality score for dry (37.2) than for wet processing (29.1). These results generally underline the complex interaction effects between altitude and shade or postharvest processing on biochemical composition and quality of green arabica coffee beans. Copyright © 2017. Published by Elsevier Ltd.

Comparative Physiological and Proteomic Analysis Reveal Distinct Regulation of Peach Skin Quality Traits by Altitude

PubMed Central

Karagiannis, Evangelos; Tanou, Georgia; Samiotaki, Martina; Michailidis, Michail; Diamantidis, Grigorios; Minas, Ioannis S.; Molassiotis, Athanassios

2016-01-01

The role of environment in fruit physiology has been established; however, knowledge regarding the effect of altitude in fruit quality traits is still lacking. Here, skin tissue quality characters were analyzed in peach fruit (cv. June Gold), harvested in 16 orchards located in low (71.5 m mean), or high (495 m mean) altitutes sites. Data indicated that soluble solids concentration and fruit firmness at commercial harvest stage were unaffected by alitute. Peach grown at high-altitude environment displayed higher levels of pigmentation and specific antioxidant-related activity in their skin at the commercial harvest stage. Skin extracts from distinct developmental stages and growing altitudes exhibited different antioxidant ability against DNA strand-scission. The effects of altitude on skin tissue were further studied using a proteomic approach. Protein expression analysis of the mature fruits depicted altered expression of 42 proteins that are mainly involved in the metabolic pathways of defense, primary metabolism, destination/storage and energy. The majority of these proteins were up-regulated at the low-altitude region. High-altitude environment increased the accumulation of several proteins, including chaperone ClpC, chaperone ClpB, pyruvate dehydrogenase E1, TCP domain class transcription factor, and lipoxygenase. We also discuss the altitude-affected protein variations, taking into account their potential role in peach ripening process. This study provides the first characterization of the peach skin proteome and helps to improve our understanding of peach's response to altitude. PMID:27891143

The different mechanisms of hypoxic acclimatization and adaptation in Lizard Phrynocephalus vlangalii living on Qinghai-Tibet Plateau.

PubMed

He, Jianzheng; Xiu, Minghui; Tang, Xiaolong; Yue, Feng; Wang, Ningbo; Yang, Shaobin; Chen, Qiang

2013-03-01

Phrynocephalus vlangalii is a species of lizard endemic in China, which lives on Qinghai-Tibet Plateau ranging from 2000 to 4600 m above sea level. In this study, P. vlangalii were collected from low altitude (2750 m) and high altitude (4564 m). The lizards from low altitude were acclimatized in simulated hypoxic chamber (equivalent to 4600 m) for 7, 15, and 30 days. The hematological parameters, heart weight, myocardial capillary density, and myocardial enzyme activities were examined. The results showed that acclimatization to hypoxia significantly increased hemoglobin concentration ([Hb]), hematocrit (Hct), heart weight (HW), heart weight to body mass (HW/BM), lactate dehydrogenase (LDH) activity, but markedly decreased mean corpuscular hemoglobin concentration (MCHC) and succinate dehydrogenase (SDH) activity. Red blood cell (RBC) count, body mass (BM), myocardial capillary density did not change markedly during hypoxic acclimatization. On the other hand, [Hb], Hct, MCHC, HW/BM, myocardium capillary density, and SDH activity of P. vlangalii from high altitude were remarkably higher than those from low-altitude; however, LDH activity of high-altitude P. vlangalii was lower than that of low-altitude lizards. There was no significant difference in HW or BM between populations of high-altitude and low-altitude. Based on the present data, we suggest that P. vlangalii has special anatomical, physiological, and biochemical accommodate mechanisms to live in hypoxic environment, and the regulative mechanisms are different between hypoxic acclimatization and adaptation. Copyright © 2013 Wiley Periodicals, Inc.

Correcting haemoglobin cut-offs to define anaemia in high-altitude pregnant women in Peru reduces adverse perinatal outcomes.

PubMed

Gonzales, Gustavo F; Tapia, Vilma; Gasco, Manuel

2014-07-01

To determine if correction of cut-offs of haemoglobin levels to define anaemia at high altitudes affects rates of adverse perinatal outcomes. Data were obtained from 161,909 mothers and newborns whose births occurred between 1,000 and 4,500 m above sea level (masl). Anaemia was defined with or without correction of haemoglobin (Hb) for altitude as Hb <11 g/dL. Correction of haemoglobin per altitude was performed according to guidelines from the World Health Organization. Rates of stillbirths and preterm births were also calculated. Stillbirth and preterm rates were significantly reduced in cases of anaemia calculated after correction of haemoglobin for altitude compared to values obtained without Hb correction. At high altitudes (3,000-4,500 masl), after Hb correction, the rate of stillbirths was reduced from 37.7 to 18.3 per 1,000 live births (p < 0.01); similarly, preterm birth rates were reduced from 13.1 to 8.76 % (p < 0.01). The odds ratios for stillbirths and for preterm births were also reduced after haemoglobin correction. At high altitude, correction of maternal haemoglobin should not be performed to assess the risks for preterm birth and stillbirth. In fact, using low altitude Hb cut-off is associated with predicting those at risk.

Identification of novel serum peptide biomarkers for high-altitude adaptation: a comparative approach

NASA Astrophysics Data System (ADS)

Yang, Juan; Li, Wenhua; Liu, Siyuan; Yuan, Dongya; Guo, Yijiao; Jia, Cheng; Song, Tusheng; Huang, Chen

2016-05-01

We aimed to identify serum biomarkers for screening individuals who could adapt to high-altitude hypoxia at sea level. HHA (high-altitude hypoxia acclimated; n = 48) and HHI (high-altitude hypoxia illness; n = 48) groups were distinguished at high altitude, routine blood tests were performed for both groups at high altitude and at sea level. Serum biomarkers were identified by comparing serum peptidome profiling between HHI and HHA groups collected at sea level. Routine blood tests revealed the concentration of hemoglobin and red blood cells were significantly higher in HHI than in HHA at high altitude. Serum peptidome profiling showed that ten significantly differentially expressed peaks between HHA and HHI at sea level. Three potential serum peptide peaks (m/z values: 1061.91, 1088.33, 4057.63) were further sequence identified as regions of the inter-α trypsin inhibitor heavy chain H4 fragment (ITIH4 347-356), regions of the inter-α trypsin inhibitor heavy chain H1 fragment (ITIH1 205-214), and isoform 1 of fibrinogen α chain precursor (FGA 588-624). Expression of their full proteins was also tested by ELISA in HHA and HHI samples collected at sea level. Our study provided a novel approach for identifying potential biomarkers for screening people at sea level who can adapt to high altitudes.

Genomic analysis identified a potential novel molecular mechanism for high-altitude adaptation in sheep at the Himalayas.

PubMed

Gorkhali, Neena Amatya; Dong, Kunzhe; Yang, Min; Song, Shen; Kader, Adiljian; Shrestha, Bhola Shankar; He, Xiaohong; Zhao, Qianjun; Pu, Yabin; Li, Xiangchen; Kijas, James; Guan, Weijun; Han, Jianlin; Jiang, Lin; Ma, Yuehui

2016-07-22

Sheep has successfully adapted to the extreme high-altitude Himalayan region. To identify genes underlying such adaptation, we genotyped genome-wide single nucleotide polymorphisms (SNPs) of four major sheep breeds living at different altitudes in Nepal and downloaded SNP array data from additional Asian and Middle East breeds. Using a di value-based genomic comparison between four high-altitude and eight lowland Asian breeds, we discovered the most differentiated variants at the locus of FGF-7 (Keratinocyte growth factor-7), which was previously reported as a good protective candidate for pulmonary injuries. We further found a SNP upstream of FGF-7 that appears to contribute to the divergence signature. First, the SNP occurred at an extremely conserved site. Second, the SNP showed an increasing allele frequency with the elevated altitude in Nepalese sheep. Third, the electrophoretic mobility shift assays (EMSA) analysis using human lung cancer cells revealed the allele-specific DNA-protein interactions. We thus hypothesized that FGF-7 gene potentially enhances lung function by regulating its expression level in high-altitude sheep through altering its binding of specific transcription factors. Especially, FGF-7 gene was not implicated in previous studies of other high-altitude species, suggesting a potential novel adaptive mechanism to high altitude in sheep at the Himalayas.

Altitude-Test-Chamber Investigation of a Solar Afterburner on the 24C Engine I - Operational Characteristics and Altitude Limits

NASA Technical Reports Server (NTRS)

1948-01-01

An altitude-test-chamber investigation was conducted to determine the operational characteristics and altitude blow-out limits of a Solar afterburner in a 24C engine. At rated engine speed and maximum permissible turbine-discharge temperature, the altitude limit as determined by combustion blow-out occurred as a band of unstable operation of about 8000 feet altitude in width with maximum altitude limits from 32,000 feet at a Mach number of 0.3 to about 42,000 feet at a Mach number of 1.0. The maximum fuel-air ratio of the afterburner, as limited by maximum permissible turbine-discharge gas temperatures at rated engine speed, varied between 0.0295 and 0.0380 over a range of flight Mach numbers from 0.25 to 1.0 and at altitudes of 20,000 and 30,000 feet. Over this range of operating conditions, the fuel-air ratio at which lean blow-out occurred was from 10 to 19 percent below these maximum fuel-air ratios. Combustion was very smooth and uniform during operation; however, ignition of the burner was very difficult throughout the investigation. A failure of the flame holder after 12 hours and 15 minutes of afterburner operation resulted in termination of the investigation.

Excitation of Earth-ionosphere waveguide in the ELF and lower VLF bands by modulated ionospheric current

NASA Astrophysics Data System (ADS)

Field, E. C.; Bloom, R. M.

1993-05-01

In this report, the principal of reciprocity is used in conjunction with a full-wave propagation code to calculate ground-level fields excited by ionospheric currents modulated at frequencies between 50 and 100 Hz with HF heaters. Results show the dependence on source orientation, altitude, and dimension and therefore pertain to experiments using the HIPAS or HAARP ionospheric heaters. In the end-fire mode, the waveguide excitation efficiency of an ELF HED in the ionosphere is up to 20 dB greater than for a ground-based antenna, provided its altitude does not exceed 80 to 90 km. The highest efficiency occurs for a source altitude of around 70 km; if that altitude is raised to 100 km, the efficiency drops by about 20 dB in the day and 10 dB at night. That efficiency does not account for the greater conductivity modulation that might be achieved at altitudes greater than 70 km, however. The trade-off between the altitude dependencies of the excitation efficiency and maximum achievable modulation depends on the ERP of the HF heater, the optimum altitude increasing with increasing ERP. For HIPAS the best modulation altitude is around 70 km, whereas for HAARP there might be marginal value in modulating at attitudes as high as 100 km.

System for indicating fuel-efficient aircraft altitude

NASA Technical Reports Server (NTRS)

Gary, B. L. (Inventor)

1984-01-01

A method and apparatus are provided for indicating the altitude at which an aircraft should fly so the W/d ratio (weight of the aircraft divided by the density of air) more closely approaches the optimum W/d for the aircraft. A passive microwave radiometer on the aircraft is directed at different angles with respect to the horizon to determine the air temperature, and therefore the density of the air, at different altitudes. The weight of the aircraft is known. The altitude of the aircraft is changed to fly the aircraft at an altitude at which is W/d ratio more closely approaches the optimum W/d ratio for that aircraft.

Characterization of Atmospheric Turbulence as a Function of Altitude

NASA Technical Reports Server (NTRS)

Prasad, Suparnamaaya; Ivanco, Marie L.; Ivanco, Thomas G.; Ancel, Ersin

2017-01-01

A novel radical shape change approach (Aerodynamically Actuated Radical Shape Change concept) was developed at NASA Langley Research Center. The radical shape change enables cruise at a lowered altitude of 15-25,000 feet and yields substantial performance and environmental benefits. This lowered altitude has however raised concerns in the community due to past experience with decreased ride quality in this altitude range. This paper describes the analysis performed by the team to address this concern. First, the team assessed and quantified turbulence occurrence as a function of altitude. Secondly, the team analyzed the effects of turbulence gust loads on the proposed concept when compared to conventional aircraft.

Preliminary Results of British Nene II Engine Altitude-Chamber Performance Investigation. I - Altitude Performance Using Standard 18.75-Inch-Diameter Jet Nozzle. 1; Altitude Performance Using Standard 18.75-Inch-Diameter Jet Nozzle

NASA Technical Reports Server (NTRS)

Barson, Zelmar; Wilsted, H. D.

1948-01-01

An investigation is being conducted to determine the altitude performance characteristics of the British Nene II engine and its components. The present paper presents the preliminary results obtained using a standard jet nozzle. The test results presented are for conditions simulating altitudes from sea level to 60,000 feet and ram pressure ratios from 1.0 to 2.3. These ram pressure ratios correspond to flight Mach numbers between zero and 1.16 assuming a 100 percent ram recovery.

Health, Safety and Performance in High Altitude Observatories: A Sustainable Approach

NASA Astrophysics Data System (ADS)

Böcker, Michael; Vogt, Joachim; Christ, Oliver; Müller-Leonhardt, Alice

2009-09-01

The research project “Optimising Performance, Health and Safety in High Altitude Observatories” was initiated by ESO to establish an approach to promote the well-being of staff working at its high altitude observatories, and in particular at the Antiplano de Chajnantor. A survey by a questionnaire given to both workers and visitors was employed to assess the effects of working conditions at high altitude. Earlier articles have outlined the project and reported early results. The final results and conclusions are presented, together with a concept for sustainable development to improve the performance, health and safety at high altitude employing Critical Incident Stress Management.

Characteristics and performance of thin LaBr3(Ce) crystal for hard X-ray astronomy

NASA Astrophysics Data System (ADS)

Manchanda, R. K.

2011-01-01

We have developed a new detector using thin lanthanum bromide crystal (32 × 3 mm) for use in X-ray astronomy. The instrument was launched in high altitude balloon flight on two different occasions, December 21, 2007, which reached a ceiling altitude of 4.3 mbs and April 25, 2008 reaching a ceiling altitude 2.8 mbs. The observed background counting rate at the ceiling altitude of 4 mbs was ˜4 × 10-3 ct cm-2 s-1 keV-1 sr-1. This paper describes the details of the experiment, the detector characteristics, and the background behaviour at the ceiling altitude.

Design and Development of a High Altitude Protective Assembly.

DTIC Science & Technology

CWU-3/P ANTIGRAVITY SUITS, CWU-12/P ANTIEXPOSURE SUITS, HAPA(HIGH ALTITUDE PROTECTIVE ASSEMBLIES), *HIGH ALTITUDE PROTECTIVE ASSEMBLIES, LPU-3/P LIFE PRESERVERS, MA-3 VENTILATION GARMENTS, PARACHUTE HARNESSES, PARTIAL PRESSURE SUITS.

The variation in engine power with altitude determined from measurements in flight with a hub dynamometer

NASA Technical Reports Server (NTRS)

Gove, W D

1929-01-01

The rate of change in power of aircraft engines with altitude has been the subject of considerable discussion. Only a small amount of data from direct measurements of the power delivered by airplane engines during flight, however, has been published. This report presents the results of direct measurements of the power delivered by a Liberty 12 airplane engine taken with a hub dynamometer at standard altitudes from zero to 13,000 feet. Six flights were made with the engine installed in a modified DH-4 airplane. The experimental relation of brake horsepower to altitude is compared with two theoretical relations and with the experimental results, for a second Liberty 12 engine, given in NACA Technical Report no. 252. The rate of change in power with altitude of a third Liberty engine, measured with a calibrated propeller, is also given for comparison. The data presented substantiate the theoretical relation of brake horsepower to altitude based on the correction of ground level indicated horsepower for change in atmospheric temperature and pressure with the subsequent deduction of friction horsepower corrected for altitude. (author)

Integration of radar altimeter, precision navigation, and digital terrain data for low-altitude flight

NASA Technical Reports Server (NTRS)

Zelenka, Richard E.

1992-01-01

Avionic systems that depend on digitized terrain elevation data for guidance generation or navigational reference require accurate absolute and relative distance measurements to the terrain, especially as they approach lower altitudes. This is particularly exacting in low-altitude helicopter missions, where aggressive terrain hugging maneuvers create minimal horizontal and vertical clearances and demand precise terrain positioning. Sole reliance on airborne precision navigation and stored terrain elevation data for above-ground-level (AGL) positioning severely limits the operational altitude of such systems. A Kalman filter is presented which blends radar altimeter returns, precision navigation, and stored terrain elevation data for AGL positioning. The filter is evaluated using low-altitude helicopter flight test data acquired over moderately rugged terrain. The proposed Kalman filter is found to remove large disparities in predicted AGL altitude (i.e., from airborne navigation and terrain elevation data) in the presence of measurement anomalies and dropouts. Previous work suggested a minimum clearance altitude of 220 ft AGL for a near-terrain guidance system; integration of a radar altimeter allows for operation of that system below 50 ft, subject to obstacle-avoidance limitations.

A preliminary design and analysis of an advanced heat-rejection system for an extreme altitude advanced variable cycle diesel engine installed in a high-altitude advanced research platform

NASA Technical Reports Server (NTRS)

Johnston, Richard P.

1992-01-01

Satellite surveillance in such areas as the Antarctic indicates that from time to time concentration of ozone grows and shrinks. An effort to obtain useful atmospheric data for determining the causes of ozone depletion would require a flight capable of reaching altitudes of at least 100,000 ft and flying subsonically during the sampling portion of the mission. A study of a heat rejection system for an advanced variable cycle diesel (AVCD) engine was conducted. The engine was installed in an extreme altitude, high altitude advanced research platform. Results indicate that the waste heat from an AVCD engine propulsion system can be rejected at the maximum cruise altitude of 120,000 ft. Fifteen performance points, reflecting the behavior of the engine as the vehicle proceeded through the mission, were used to characterize the heat exchanger operation. That portion of the study is described in a appendix titled, 'A Detailed Study of the Heat Rejection System for an Extreme Altitude Atmospheric Sampling Aircraft,' by a consultant, Mr. James Bourne, Lytron, Incorporated.

[Relationship of high altitude de-adaptation with acute high altitude response and cardiac function].

PubMed

Yang, Sheng-Yue; Zhou, Qi-Quan; Feng, En-Zhi; Yan, Zi-Qiang; Tian, Zhong-Xin; Yin, He; Shi, Zi-Fu

2013-09-01

To assess the relationship of high altitude de-adaptation response (HADAR) with acute high altitude response (AHAR) and cardiac function. Ninety-six military personnel of rapid entering into high altitude (3 700 to 4 800 m) with strong physical work were analyzed, all subjects were male, aged 18 - 35 years. According to the symptomatic scores of AHAR were divided into 3 groups: sever AHAR (group A, 24), mild to moderate AHAR (group B, 47) and non-AHAR (group C, 25) at high altitude. According to the symptomatic scores of HADAR were divided into 3 groups: severe HADAR (group E, 19), mild to moderate HADAR (group F, 40) and non-HADAR (group G, 37) after return to lower altitude (1 500 m). Mean pulmonary arterial pressure (mPAP), right ventricular internal dimension (RVID), outflow tract of right ventricle (RVOT), left ventricular internal dimension (LVID), left ventricular ejection fraction (LVEF), cardiac muscle work index (Tei index), creatine kinase isoenzymes-MB (CK-MB), lactic dehydrogenase isoenzyme-1 (LDH-1) were measured at high altitude stayed 50 days and after return to lower altitude 12 h, 15 d, and 30 d. Fifty healthy volunteers (group D) at 1 500 m altitude served as control. Level of mPAP, RVID, RVOT, RVID/LVID ratio, Tei index, CK-MB,and LDH-1 were higher, and LVEF was lower in group A than those in group B, C and D, there were significant differences between group B and C, C and D (all P < 0.01). AHAR scores were positively correlated with HADAR scores (r = 0.863, P < 0.01). Twelve hours after return to lower altitude, level of mPAP, RVID, RVOT, RVI/LVID ratio, Tei index, CK-MB, and LDH-1 were higher, and LVEF was lower in group E than those in group F, G and D, there were significant differences between group F and G, G and D (all P < 0.01). Fifteen days after return to lower altitude, level of mPAP, RVID, RVOT, RVID/LVID ratio were higher in group E than those in group F, G, and D, there were significant differences between group F and G, and D (P < 0.01 or P < 0.05), there were no significant differences between group G and D (all P > 0.05), LVEF, Tei index, CK-MB, LDH-1 showed no significant differences among groups (all P > 0.05). Thirty days after return to lower altitude, these parameters in group E, F, and G showed no significantly differences compared with those of group D (all P > 0.05). The severity of HADAR is associated with severity of AHAR and cardiac injury, the more serious of AHAR and cardiac injury at high altitude, the more serious of HADAR and cardiac injury after return to lower altitude, the more long of restore of right cardiac morphologic injury.

Alternative surveillance technology for the Gulf of Mexico

DOT National Transportation Integrated Search

2004-04-26

In the Gulf of Mexico, there are two major operating aviation users: low altitude offshore and high altitude. The low altitude offshore operators are primarily helicopter fleets supporting the oil and gas exploration efforts; their traffic typically ...

Preliminary Evaluation of Altitude Scaling for Turbofan Engine Ice Crystal Icing

NASA Technical Reports Server (NTRS)

Tsao, Jen-Ching

2017-01-01

Preliminary evaluation of altitude scaling for turbofan engine ice crystal icing simulation was conducted during the 2015 LF11 engine icing test campaign in PSL.The results showed that a simplified approach for altitude scaling to simulate the key reference engine ice growth feature and associated icing effects to the engine is possible. But special considerations are needed to address the facility operation limitation for lower altitude engine icing simulation.

Critical Care Performance in a Simulated Military Aircraft Cabin Environment

DTIC Science & Technology

2007-01-01

resources are depleted due to other factors such as fatigue or anxiety . The decline in 21 accuracy of serial reaction as time progresses is perhaps the most...exposure to moderate simulated altitude levels could modify heart rate variability ( HRV ) during exercise. HRV is indicative of the autonomic nervous...various altitudes in a hypobaric chamber, and the ascent to the different altitudes was separated by 2 hours. Acute effects of altitude exposure on HRV

Effect of Propranolol on Metabolic Responses to Exercise at High Altitude

DTIC Science & Technology

1988-02-01

the low carbohydrate/ hypocaloric diet often assumed by altitude sojourners due to anorexia or ration restrictions. The results of the present...end of the altitude sojourn than at sea level. Although the subjects in this study consumed an ad libitum diet , they 15 were strongly encouraged to...consume a high carbohydrate diet particularly during the last five days at high altitude preceding the biopsy experiment. Dietary records were not kept

Loran C Coverage in Alaska after Dual Rating Port Clarence

DTIC Science & Technology

1988-06-01

Desired flight altitudes were 1000 feet above ground level . Due to the limited number of airports which could support the aircraft and logistics, a higher...designed to evaluate the feasibility of adding LORSTA Port Clarence as a secondary on the Gulf of Alaska chain. Signal strength and noise levels were...altitude was necessary for fuel efficiency. The higher altitudes allowed longer flight segments. The target altitude was 17,000 feet mean sea level

Circulatory adaptation to long-term high altitude exposure in Aymaras and Caucasians.

PubMed

Stuber, Thomas; Scherrer, Urs

2010-01-01

About 30 million people live above 2500 m in the Andean Mountains of South America. Among them are 5.5 million Aymaras, an ethnic group with its own language, living on the altiplano of Bolivia, Peru, and northern Chile at altitudes of up to 4400 m. In this high altitude region traces of human population go back for more than 2000 years with constant evolutionary pressure on its residents for genetic adaptation to high altitude. Aymaras as the assumed direct descendents of the ancient cultures living in this region were the focus of much research interest during the last decades and several distinctive adaptation patterns to life at high altitude have been described in this ethnic group. The aim of this article was to review the physiology and pathophysiology of circulatory adaptation and maladaptation to longtime altitude exposure in Aymaras and Caucasians.

[Effects of simulated hypoxia on dielectric properties of mouse erythrocytes].

PubMed

Ma, Qing; Tang, Zhi-Yuan; Wang, Qin-Wen; Zhao, Xin

2008-02-01

To explore the influence of simulated altitude hypoxia on dielectric properties of mouse erythrocytes. Experimental animals were divided into the plain control group(control) and simulated altitude hypoxia group (altitude). The AC impedance of mouse erythrocytes was measured with the Agilent 4294A impedance analyzer, the influence of simulated altitude hypoxia on dielectric properties of mouse erythrocytes was observed by cell dielectric spectroscopy, Cole-Cole plots, loss factor spectrum, loss tangent spectrum, and curve fitting analysis of Cole-Cole equation. After mice were exposed to hypoxia at simulated 5000 m altitude for 4 weeks, permittivity at low frequency (epsilonl) and dielectric increment (deltaepsilon) increased 57% and 59% than that of control group respectively, conductivity at low frequency (kappal) and conductivity at high frequency (kappah) reduced 49% and 11% than that of control group respectively. The simulated altitude hypoxia could arise to increase dielectric capability and depress conductive performance on mouse erythrocytes.

Highest permanent human habitation.

PubMed

West, John B

2002-01-01

The aim of this analysis was to determine the altitude of the highest permanent human habitation in the hope that this will throw some light on what determines the highest altitude that a community can tolerate indefinitely. A number of places where people have lived at very high altitudes for long periods of time are reviewed. Individuals have lived for as long as 2 yr at an altitude of 5950 m, and there was a miner's camp at 5300 m for several years. The highest permanently inhabited town in the world at the present time appears to be La Rinconada, a mining village of over 7000 people in southern Peru at an altitude of up to 5100 m, which has been in existence for over 40 yr. The altitude of the highest permanent human habitation is determined partly by economic factors, rather than solely by human tolerance to hypoxia.

Altitude acts as an environmental filter on phylogenetic composition, traits and diversity in bee communities.

PubMed

Hoiss, Bernhard; Krauss, Jochen; Potts, Simon G; Roberts, Stuart; Steffan-Dewenter, Ingolf

2012-11-07

Knowledge about the phylogeny and ecology of communities along environmental gradients helps to disentangle the role of competition-driven processes and environmental filtering for community assembly. In this study, we evaluated patterns in species richness, phylogenetic structure and life-history traits of bee communities along altitudinal gradients in the Alps, Germany. We found a linear decline in species richness and abundance but increasing phylogenetic clustering in communities with increasing altitude. The proportion of social- and ground-nesting species, as well as mean body size and altitudinal range of bee communities, increased with increasing altitude, whereas the mean geographical distribution decreased. Our results suggest that community assembly at high altitudes is dominated by environmental filtering effects, whereas the relative importance of competition increases at low altitudes. We conclude that inherent phylogenetic and ecological species attributes at high altitudes pose a threat for less competitive alpine specialists with ongoing climate change.

Altitude acts as an environmental filter on phylogenetic composition, traits and diversity in bee communities

PubMed Central

Hoiss, Bernhard; Krauss, Jochen; Potts, Simon G.; Roberts, Stuart; Steffan-Dewenter, Ingolf

2012-01-01

Knowledge about the phylogeny and ecology of communities along environmental gradients helps to disentangle the role of competition-driven processes and environmental filtering for community assembly. In this study, we evaluated patterns in species richness, phylogenetic structure and life-history traits of bee communities along altitudinal gradients in the Alps, Germany. We found a linear decline in species richness and abundance but increasing phylogenetic clustering in communities with increasing altitude. The proportion of social- and ground-nesting species, as well as mean body size and altitudinal range of bee communities, increased with increasing altitude, whereas the mean geographical distribution decreased. Our results suggest that community assembly at high altitudes is dominated by environmental filtering effects, whereas the relative importance of competition increases at low altitudes. We conclude that inherent phylogenetic and ecological species attributes at high altitudes pose a threat for less competitive alpine specialists with ongoing climate change. PMID:22933374

Ice-based altitude distribution of natural radiation annual exposure rate in the Antarctica zone over the latitude range 69 degrees S-77 degrees S using a pair-filter thermoluminescence method.

PubMed

Nakajima, T; Kamiyama, T; Fujii, Y; Motoyama, H; Esumi, S

1995-12-01

Both ice-based altitude distributions of natural ionizing radiation exposure and the quasi-effective energy of natural radiation over Antartica over the latitude range 69 degrees S - 77 degrees S during approx. 500 days were measured using thermoluminescent dosimeters. The results shows that dependence on altitude above sea level of the exposure rate increases by almost three-fold with each increase of 2000 m of altitude, thus deviating from the general rule stating that the exposure rate should double with each 2000 m. Although the exposure rate shows a dependence on altitude, altitude dependence of the quasi-effective energy of natural radiation over Antartica is not observed. In the present study it is observed that natural radiation occurring over the ice base of Antartica consists mainly of cosmic rays.

Exhaust emission calibration of two J-58 afterburning turbojet engines at simulated high-altitude, supersonic flight conditions

NASA Technical Reports Server (NTRS)

Holdeman, J. D.

1976-01-01

Emissions of total oxides of nitrogen, nitric oxide, unburned hydrocarbons, carbon monoxide, and carbon dioxide from two J-58 afterburning turbojet engines at simulated high-altitude flight conditions are reported. Test conditions included flight speeds from Mach 2 to 3 at altitudes from 16.0 to 23.5 km. For each flight condition exhaust measurements were made for four or five power levels, from maximum power without afterburning through maximum afterburning. The data show that exhaust emissions vary with flight speed, altitude, power level, and radial position across the exhaust. Oxides of nitrogen emissions decreased with increasing altitude and increased with increasing flight speed. Oxides of nitrogen emission indices with afterburning were less than half the value without afterburning. Carbon monoxide and hydrocarbon emissions increased with increasing altitude and decreased with increasing flight speed. Emissions of these species were substantially higher with afterburning than without.

Southern hemisphere observations of a long-term decrease in F region altitude and thermospheric wind providing possible evidence for global thermospheric cooling

NASA Astrophysics Data System (ADS)

Jarvis, M. J.; Jenkins, B.; Rodgers, G. A.

1998-09-01

F region peak heights, derived from ionospheric scaled parameters through 38-year data series from both Argentine Islands (65°S, 64°W) and Port Stanley (52°S, 58°W) have been analyzed for signatures of secular change. Long-term changes in altitude, which vary with month and time of day, were found at both sites. The results can be interpreted either as a constant decrease in altitude combined with a decreasing thermospheric wind effect or as a constant decrease in altitude which is altitude-dependent. Both interpretations leave inconsistencies when the results from the two sites are compared. The estimated long-term decrease in altitude is of a similar order of magnitude to that which has been predicted to result in the thermosphere from anthropogenic change related to greenhouse gases. Other possibilities should not, however, be ruled out.

Certification and safety aspects relating to the transport of passengers on high altitude balloons in Europe

NASA Astrophysics Data System (ADS)

Schoenmaker, Annelie

2014-07-01

High-altitude balloons typically fly between 25 and 50 km in altitude, which, while below the Karman line of 100 km, is yet far above the altitudes typically flown by aircraft. For example, the highest-flying commercial aircraft - the Concorde - had a maximum cruising altitude of only 18 km. zero2infinity, a Spanish company, is currently developing a pressurized pod named “bloon” which will be capable of lifting six people, including two pilot crew members and four paying passengers, to an altitude of 36 km through the use of high-altitude balloons. The boundary between Airspace and Outer Space has never been legally defined, mostly because of the lack of activities taking place between the altitude where airplanes fly and the lowest orbiting spacecraft. High-altitude balloons do fly at these in-between altitudes and the prospect of commercializing access to these parts of the stratosphere poses some questions in a new light. Given the relatively low altitude at which they fly, it may well be that these types of balloons would be considered to operate exclusively within air space. However, given the technology involved in crewed high altitude balloon flights, which is more similar to spacecraft engineering than to traditional hot-air or gas ballooning, it is necessary to evaluate the various legal regimes, codes, and regulations that would apply to such flights, especially regarding licenses and liabilities. For high altitude balloon flights commencing in Europe, the European Aviation Safety Agency (EASA) would very likely be the competent certification or licensing agency for these flights, although there would likely be input from various national aviation authorities as well. However, because the European Commission (EC) has not yet issued regulations regarding commercial spaceflight, particularly the use of high altitude balloons, new rules and regulations governing such flights may still need to be drafted and promulgated. With the development of suborbital passenger vehicles such as bloon, Spaceplane as well as SpaceShipTwo (which is British-owned) this is clearly the appropriate time for the EC or other competent institutions to issue regulations regarding suborbital passenger flight. Rules and regulations regarding suborbital passenger transport such as liability and waivers to protect third parties, governments, and operators, need to be addressed by the European Union (EU) as a whole or at least by national or regional governments wishing to attract suborbital passenger flights to their territory. After all, it would be in Europe's financial and other interests to create and foster a favorable legal and commercial environment for the aerospace business within the borders of the EU.

Application of a sensory-instrumental tool to study apple texture characteristics shaped by altitude and time of harvest.

PubMed

Charles, Mathilde; Corollaro, Maria Laura; Manfrini, Luigi; Endrizzi, Isabella; Aprea, Eugenio; Zanella, Angelo; Corelli Grappadelli, Luca; Gasperi, Flavia

2018-02-01

Texture is important in the preferences of apple consumers. Of the pre-harvest factors affecting fruit quality and especially texture, altitude and subsequent climatic conditions are crucial, determining differences in the physiological mechanisms of fruit growth, ripening stage and chemical composition, as demonstrated by several studies. This work applies a detailed sensory-instrumental protocol developed in a previous paper to investigate the impact of altitude, time of harvest and their cross-effect on sensory characteristics of apple, with a focus on texture. Sensory differences were found in relation to altitude, although the profile results were mainly affected by the time of harvest. Fruit from lower altitude was described as juicier, crunchier and sweeter than samples from higher altitude, which were floury, sourer and more astringent. Texture performance, soluble solids content and titratable acidity corroborated this sensory description. Moreover, anatomical data showed that fruit from lower altitude had a larger volume, a higher number of cells and a higher percentage of intercellular spaces. We demonstrated that differences between fruit from various altitudes can be perceived through human senses, and that the proposed sensory-instrumental tool can be used to describe such differences. This study brings more understanding about the impact of altitude and time of harvest on apple sensory properties. This work could support apple producers, from semi-mountainous regions (Alps, Tyrol, etc.), in advertising and valorising their products with their specific characteristics in a more efficient manner. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Altitude-related hypoxia: risk assessment and management for passengers on commerical aircraft.

PubMed

Mortazavi, Amir; Eisenberg, Mark J; Langleben, David; Ernst, Pierre; Schiff, Renee L

2003-09-01

Individuals with pulmonary and cardiac disorders are particularly at risk of developing hypoxemia at altitude. Our objective is to describe the normal and maladaptive physiological responses to altitude-related hypoxia, to review existing methods and guidelines for preflight assessment of air travelers, and to provide recommendations for treatment of hypoxia at altitude. Falling partial pressure of oxygen with altitude results in a number of physiologic adaptations including hyperventilation, pulmonary vasoconstriction, altered ventilation/perfusion matching, and increased sympathetic tone. According to three guideline statements, the arterial pressure of oxygen (PaO2) should be maintained above 50 to 55 mm Hg at all altitudes. General indicators such as oxygen saturation and sea level blood gases may be useful in predicting altitude hypoxia. More specialized techniques for estimation of altitude PaO2, such as regression equations, hypoxia challenge testing, and hypobaric chamber exposure have also been examined. A regression equation using sea level PaO2 and spirometric parameters can be used to estimate PaO2 at altitude. Hypoxia challenge testing, performed by exposing subjects to lower inspired FIO2 at sea level may be more precise. Hypobaric chamber exposure, the gold standard, mimics lower barometric pressure, but is mainly used in research. Oxygen supplementation during air travel is needed for individuals with an estimated PaO2 (8000 ft) below 50 mmHg. There are a number of guidelines for the pre-flight assessment of patients with pulmonary and/or cardiac diseases. However, these data are based on small studies in patients with a limited group of diseases.

Enhancing team-sport athlete performance: is altitude training relevant?

PubMed

Billaut, François; Gore, Christopher J; Aughey, Robert J

2012-09-01

Field-based team sport matches are composed of short, high-intensity efforts, interspersed with intervals of rest or submaximal exercise, repeated over a period of 60-120 minutes. Matches may also be played at moderate altitude where the lower oxygen partial pressure exerts a detrimental effect on performance. To enhance run-based performance, team-sport athletes use varied training strategies focusing on different aspects of team-sport physiology, including aerobic, sprint, repeated-sprint and resistance training. Interestingly, 'altitude' training (i.e. living and/or training in O(2)-reduced environments) has only been empirically employed by athletes and coaches to improve the basic characteristics of speed and endurance necessary to excel in team sports. Hypoxia, as an additional stimulus to training, is typically used by endurance athletes to enhance performance at sea level and to prepare for competition at altitude. Several approaches have evolved in the last few decades, which are known to enhance aerobic power and, thus, endurance performance. Altitude training can also promote an increased anaerobic fitness, and may enhance sprint capacity. Therefore, altitude training may confer potentially-beneficial adaptations to team-sport athletes, which have been overlooked in contemporary sport physiology research. Here, we review the current knowledge on the established benefits of altitude training on physiological systems relevant to team-sport performance, and conclude that current evidence supports implementation of altitude training modalities to enhance match physical performances at both sea level and altitude. We hope that this will guide the practice of many athletes and stimulate future research to better refine training programmes.

Phenotypic plasticity and genetic adaptation to high-altitude hypoxia in vertebrates.

PubMed

Storz, Jay F; Scott, Graham R; Cheviron, Zachary A

2010-12-15

High-altitude environments provide ideal testing grounds for investigations of mechanism and process in physiological adaptation. In vertebrates, much of our understanding of the acclimatization response to high-altitude hypoxia derives from studies of animal species that are native to lowland environments. Such studies can indicate whether phenotypic plasticity will generally facilitate or impede adaptation to high altitude. Here, we review general mechanisms of physiological acclimatization and genetic adaptation to high-altitude hypoxia in birds and mammals. We evaluate whether the acclimatization response to environmental hypoxia can be regarded generally as a mechanism of adaptive phenotypic plasticity, or whether it might sometimes represent a misdirected response that acts as a hindrance to genetic adaptation. In cases in which the acclimatization response to hypoxia is maladaptive, selection will favor an attenuation of the induced phenotypic change. This can result in a form of cryptic adaptive evolution in which phenotypic similarity between high- and low-altitude populations is attributable to directional selection on genetically based trait variation that offsets environmentally induced changes. The blunted erythropoietic and pulmonary vasoconstriction responses to hypoxia in Tibetan humans and numerous high-altitude birds and mammals provide possible examples of this phenomenon. When lowland animals colonize high-altitude environments, adaptive phenotypic plasticity can mitigate the costs of selection, thereby enhancing prospects for population establishment and persistence. By contrast, maladaptive plasticity has the opposite effect. Thus, insights into the acclimatization response of lowland animals to high-altitude hypoxia can provide a basis for predicting how altitudinal range limits might shift in response to climate change.

[Altitude-belt zonality of wood vegetation within mountainous regions of the Sayan Mountains: a model of ecological second-order phase transitions ].

PubMed

Sukhovol'skiĭ, V G; Ovchinnikova, T M; Baboĭ, S D

2014-01-01

As a description of altitude-belt zonality of wood vegetation, a model of ecological second-order transitions is proposed. Objects of the study have been chosen to be forest cenoses of the northern slope of Kulumyss Ridge (the Sayan Mauntains), while the results are comprised by the altitude profiles of wood vegetation. An ecological phase transition can be considered as the transition of cenoses at different altitudes from the state of presence of certain tree species within the studied territory to the state of their absence. By analogy with the physical model of second-order, phase transitions the order parameter is introduced (i.e., the area portion occupied by a single tree species at the certain altitude) as well as the control variable (i.e., the altitude of the wood vegetation belt). As the formal relation between them, an analog of the Landau's equation for phase transitions in physical systems is obtained. It is shown that the model is in a good accordance with the empirical data. Thus, the model can be used for estimation of upper and lower boundaries of altitude belts for individual tree species (like birch, aspen, Siberian fir, Siberian pine) as well as the breadth of their ecological niches with regard to altitude. The model includes also the parameters that describe numerically the interactions between different species of wood vegetation. The approach versatility allows to simplify description and modeling of wood vegetation altitude zonality, and enables assessment of vegetation cenoses response to climatic changes.

Phenotypic plasticity and genetic adaptation to high-altitude hypoxia in vertebrates

PubMed Central

Storz, Jay F.; Scott, Graham R.; Cheviron, Zachary A.

2010-01-01

High-altitude environments provide ideal testing grounds for investigations of mechanism and process in physiological adaptation. In vertebrates, much of our understanding of the acclimatization response to high-altitude hypoxia derives from studies of animal species that are native to lowland environments. Such studies can indicate whether phenotypic plasticity will generally facilitate or impede adaptation to high altitude. Here, we review general mechanisms of physiological acclimatization and genetic adaptation to high-altitude hypoxia in birds and mammals. We evaluate whether the acclimatization response to environmental hypoxia can be regarded generally as a mechanism of adaptive phenotypic plasticity, or whether it might sometimes represent a misdirected response that acts as a hindrance to genetic adaptation. In cases in which the acclimatization response to hypoxia is maladaptive, selection will favor an attenuation of the induced phenotypic change. This can result in a form of cryptic adaptive evolution in which phenotypic similarity between high- and low-altitude populations is attributable to directional selection on genetically based trait variation that offsets environmentally induced changes. The blunted erythropoietic and pulmonary vasoconstriction responses to hypoxia in Tibetan humans and numerous high-altitude birds and mammals provide possible examples of this phenomenon. When lowland animals colonize high-altitude environments, adaptive phenotypic plasticity can mitigate the costs of selection, thereby enhancing prospects for population establishment and persistence. By contrast, maladaptive plasticity has the opposite effect. Thus, insights into the acclimatization response of lowland animals to high-altitude hypoxia can provide a basis for predicting how altitudinal range limits might shift in response to climate change. PMID:21112992

Effects of altitude and exercise on pulmonary capillary integrity: evidence for subclinical high-altitude pulmonary edema.

PubMed

Eldridge, Marlowe W; Braun, Ruedi K; Yoneda, Ken Y; Walby, William F

2006-03-01

Strenuous exercise may be a significant contributing factor for development of high-altitude pulmonary edema, particularly at low or moderate altitudes. Thus we investigated the effects of heavy cycle ergometer exercise (90% maximal effort) under hypoxic conditions in which the combined effects of a marked increase in pulmonary blood flow and nonuniform hypoxic pulmonary vasoconstriction could add significantly to augment the mechanical stress on the pulmonary microcirculation. We postulated that intense exercise at altitude would result in an augmented permeability edema. We recruited eight endurance athletes and examined their bronchoalveolar lavage fluid (BALF) for red blood cells (RBCs), protein, inflammatory cells, and soluble mediators at 2 and 26 h after intense exercise under normoxic and hypoxic conditions. After heavy exercise, under all conditions, the athletes developed a permeability edema with high BALF RBC and protein concentrations in the absence of inflammation. We found that exercise at altitude (3,810 m) caused significantly greater leakage of RBCs [9.2 (SD 3.1)x10(4) cells/ml] into the alveolar space than that seen with normoxic exercise [5.4 (SD 1.2)x10(4) cells/ml]. At altitude, the 26-h postexercise BALF revealed significantly higher RBC and protein concentrations, suggesting an ongoing capillary leak. Interestingly, the BALF profiles following exercise at altitude are similar to that of early high-altitude pulmonary edema. These findings suggest that pulmonary capillary disruption occurs with intense exercise in healthy humans and that hypoxia augments the mechanical stresses on the pulmonary microcirculation.

Vascular Endothelial Function Assessed by Postischemic Diastolic Blood Pressure Is Associated with Acclimatization and Acute Mountain Sickness.

PubMed

He, Lipeng; Jiang, Yu; Su, Hai; Li, Juxiang; Cheng, Xiaoshu

2016-03-01

This study assessed whether the brachial diastolic blood pressure (DBP) decline induced by 5-minute arm ischemia is associated with acclimatization and acute mountain sickness (AMS). Forty-two age- and body mass index-matched young male residents at sea level (<400 m) or moderate altitude (1000-2000 m above sea level) were enrolled. All subjects had never been to 3200 m before. Brachial BP was measured at a station at 1380 m altitude before and 1, 5, and 10 minutes after right arm ischemia. AMS score was evaluated after 3-day training at a high altitude of 3200 m. In moderate altitude versus sea-level residents: (1) systolic BP curves for both arms overlapped well; (2) mean right arm DBP decline post right arm ischemia was larger, while left arm, which was not subjected to ischemia, did not show DBP decline in either group; and (3) AMS scores were significantly lower (3.19 ± 2.16 vs. 5.52 ± 4.58, p = 0.043) in those residing at moderate altitude compared to those from low altitude. There was a low negative correlation between AMS score and right arm area between curves-DBP (r = -0.320, p = 0.039). Moderate altitude relative to sea-level residents had a larger mean postischemic DBP decline in weak but significant association with lower mean AMS score at 3200 m. These data suggest that differences in vascular endothelial function related to altitude of residence persist during travel to high altitude and might contribute to AMS risk.

Science 101: Why Does It Take Longer to Boil Potatoes at High Altitudes?

ERIC Educational Resources Information Center

Robertson, Bill

2017-01-01

Why Does It Take Longer to Boil Potatoes at High Altitudes? This column provides background science information for elementary teachers. This month's issue looks at why water boils at different temperatures at different altitudes.

Effects of Scene-Linked Symbology on Flight Performance

DOT National Transportation Integrated Search

1997-01-01

Previous research has shown that the presence of aircraft head-up display (HUD) : symbology indicating altitude improves maintenance of altitude, but at a cost : to (ground) path-following ability. We term this the altitude/path performance : trade-o...

EXTERIOR OF ALTITUDE CHAMBERS R (TO LEFT) AND L (TO ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

EXTERIOR OF ALTITUDE CHAMBERS R (TO LEFT) AND L (TO RIGHT), FACING NORTHEAST - Cape Canaveral Air Force Station, Launch Complex 39, Altitude Chambers, First Street, between Avenue D and Avenue E, Cape Canaveral, Brevard County, FL

EXTERIOR OF ALTITUDE CHAMBERS R (TO LEFT) AND L (TO ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

EXTERIOR OF ALTITUDE CHAMBERS R (TO LEFT) AND L (TO RIGHT), FACING NORTHWEST - Cape Canaveral Air Force Station, Launch Complex 39, Altitude Chambers, First Street, between Avenue D and Avenue E, Cape Canaveral, Brevard County, FL

UHF Radar observations at HAARP with HF pump frequencies near electron gyro-harmonics and associated ionospheric effects

NASA Astrophysics Data System (ADS)

Watkins, Brenton; Fallen, Christopher; Secan, James

Results for HF modification experiments at the HAARP facility in Alaska are presented for experiments with the HF pump frequency near third and fourth electron gyro-harmonics. A UHF diagnostic radar with range resolution of 600 m was used to determine time-dependent altitudes of scattering from plasma turbulence during heating experiments. Experiments were conducted with multiple HF frequencies stepped by 20 kHz above and below the gyro-harmonic values. During times of HF heating the HAARP facility has sufficient power to enhance large-scale ionospheric densities in the lower ionosphere (about 150-200 km altitude) and also in the topside ionosphere (above about 350 km). In the lower ionosphere, time-dependent decreases of the altitude of radar scatter result from electron density enhancements. The effects are substantially different even for relatively small frequency steps of 20 kHz. In all cases the time-varying altitude decrease of radar scatter stops about 5-10 km below the gyro-harmonic altitude that is frequency dependent; we infer that electron density enhancements stop at this altitude where the radar signals stop decreasing with altitude. Experiments with corresponding total electron content (TEC) data show that for HF interaction altitudes above about 170 km there is substantial topside electron density increases due to upward electron thermal conduction. For lower altitudes of HF interaction the majority of the thermal energy is transferred to the neutral gas and no significant topside density increases are observed. By selecting an appropriate HF frequency a little greater than the gyro-harmonic value we have demonstrated that the ionospheric response to HF heating is a self-oscillating mode where the HF interaction altitude moves up and down with a period of several minutes. If the interaction region is above about 170 km this also produces a continuously enhanced topside electron density and upward plasma flux. Experiments using an FM scan with the HF frequency increasing near the gyro-harmonic value were conducted. The FM scan rate was sufficiently slow that the electron density was approximately in an equilibrium state. For these experiments the altitude of the HF interaction follows a near straight line downward parallel to the altitude-dependent gyro-harmonic level.

Cerebral blood flow and oxygenation in ovine fetus: responses to superimposed hypoxia at both low and high altitude

PubMed Central

Peňa, Jorge Pereyra; Tomimatsu, Takuji; Hatran, Douglas P; McGill, Lisa L; Longo, Lawrence D

2007-01-01

For the fetus, although the roles of arterial blood gases are recognized to be critical in the regulation of cerebral blood flow (CBF) and cerebral oxygenation, the relation of CBF, cortical tissue PO2 (t PO2), sagittal sinus PO2, and related indices of cerebral oxygenation to arterial blood gases are not well defined. This is particularly true for that fetus subjected to long-term hypoxia (LTH). In an effort to elucidate these interrelations, we tested the hypothesis that in the fetus acclimatized to high altitude, cerebral oxygenation is not compromised relative to that at low altitude. By use of a laser Doppler flowmeter with a fluorescent O2 probe, in near-term fetal sheep at low altitude (n = 8) and those acclimatized to high altitude hypoxia (3801 m for 90 ± 5 days; n = 6), we measured laser Doppler CBF (LD-CBF), t PO2, and related variables in response to 40 min superimposed hypoxia. At both altitudes, fetal LD-CBF, cerebral O2 delivery, t PO2, and several other variables including sagittal sinus PO2, correlated highly with arterial PO2 (Pa,O2). In response to superimposed hypoxia (Pa,O2 = 11 ± 1 Torr), LD-CBF was significantly blunted at high altitude, as compared with that at low altitude. In the two altitude groups fetal cerebral oxygenation was similar under both control conditions and with superimposed hypoxia, cortical t PO2 decreasing from 8 ± 1 and 6 ± 1 Torr, respectively, to 2 ± 1 Torr. Also, for these conditions sagittal sinus PO2 and [HbO2] values were similar. In response to superimposed hypoxia, cerebral metabolic rate for O2 decreased ∼50% in each group (P < 0.05). For both the fetus at low altitude and that acclimatized to high altitude LTH, we present the first dose–response data on the relation of LD-CBF, cortical t PO2, and sagittal sinus blood gas values to Pa,O2. In addition, despite differences in several variables, the fetus at high altitude showed evidence of successful acclimatization, supporting the hypothesis that such fetuses demonstrate no compromise in cerebral oxygenation. PMID:17068100

Assessment of SAGE Version 6.1 Ozone Data Quality

NASA Technical Reports Server (NTRS)

Wang, Hsiang J.; Cunnold, Derek M.; Thomason, Larry W.; Zawodny, Joseph M.; Bodeker, Greg E.

2002-01-01

The SAGE-II V6.1 ozone retrievals are shown to be of better precision at all levels and to be much more accurate than previous retrievals in the lower stratosphere below 20 km altitude. A filtering procedure for removing anomalous ozone profiles associated with volcanic aerosol/cloud effects and other identified artifacts in V6.1 ozone is described. The agreement between SAGE and ozonesondes in the mean is shown to be approximately 10% down to the tropopause. Relative to the sondes SAGE tends to slightly overestimate ozone (less than 5%) between 15 and 20 km altitude, and systematically underestimates ozone in the troposphere by approximately 30% in the regions between 8 km altitude and 2 km below the tropopause. The precisions (random errors) of SAGE ozone retrievals above 25 km altitude are estimated to be 4% or better; they are a factor of ten worse below 16 km altitude. Linear trends in the differences between coincident SAGE and ozonesondes measurement are generally less than 0.3 %/year and not significantly different from zero in 95% confidence intervals. Compared to V5.96 retrievals, ozone trend differences between 20 and 50 km altitude are approximately 0. 1 %/year, below 20 km altitude the SAGE II trends are more positive by approximately 0.2 %/year. For the 1984-1999 period the SAGE-II shows a localized ozone loss of -0.4(+/- 0.25) %/year (2gigma) in the tropics at 20 km altitude. In the lower stratosphere between 16 and 22 km altitudes, the SAGE shows significant ozone losses in the mid-latitudes in both Hemispheres during the 1979-1999 periods. The ozone trends range from -0.24(+/- 0.18) to -0.77(+/- 0.46) (2sigma)%/year. However in the 1984-1999 period, the downward trends are smaller (-0.07 to - 0.25 %/year) in this altitude range, and the trends in the integrated column from 12 to 17 km altitude in mid-latitudes (35 deg - 60 deg) are not significantly different from zero (0.1 +?- 0.6 (2sigma)%/year). Averaged over the tropics (20 deg S to 20 deg N) the ozone column above 15 km altitude exhibit a trend of -0.12 +/- 0.08 (2sigma)%/year.

Physiological Adjustments and Circulating MicroRNA Reprogramming Are Involved in Early Acclimatization to High Altitude in Chinese Han Males

PubMed Central

Liu, Bao; Huang, He; Wang, Shou-Xian; Wu, Gang; Xu, Gang; Sun, Bing-Da; Zhang, Er-Long; Gao, Yu-Qi

2016-01-01

Background: Altitude acclimatization is a physiological process that restores oxygen delivery to the tissues and promotes oxygen use under high altitude hypoxia. High altitude sickness occurs in individuals without acclimatization. Unraveling the molecular underpinnings of altitude acclimatization could help understand the beneficial body responses to high altitude hypoxia as well as the altered biological events in un-acclimatized individuals. This study assessed physiological adjustments and circulating microRNA (cmiRNA) profiles in individuals exposed to high altitude, aiming to explore altitude acclimatization in humans. Methods: Ninety volunteers were enrolled in this study. Among them, 22 individuals provided samples for microRNA arrays; 68 additional individuals constituted the validation set. Un-acclimatized individuals were identified by the Lake Louise Scoring System. Thirty-three phenotypes were recorded pre- and post-exposure to high altitude, including stress hormones, lipid profiles, hematological indices, myocardial enzyme spectrum, and liver and kidney function related enzymes. CmiRNA expression profiles were assessed using miRCURYTM LNA Array (v.18.0) screening, with data validated by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Then, associations of plasma microRNA expression with physiological adjustments were evaluated. The biological relevance of the main differentially expressed cmiRNAs was explored by bioinformatics prediction. Results: Nineteen of the 33 phenotypes were significantly altered during early altitude acclimatization, including hematological indices, lipid profiles, and stress hormones; meanwhile, 86 cmiRNAs (79 up-regulated and 7 down-regulated) showed differential expression with statistical significance. Among them, 32 and 25 microRNAs were strongly correlated with low-density lipoprotein-cholesterol and total cholesterol elevations, respectively. In addition, 22 microRNAs were closely correlated with cortisol increase. In un-acclimatized individuals, 55 cmiRNAs were up-regulated and 36 down-regulated, compared with acclimatized individuals. The HIF signaling pathway was suppressed in un-acclimatized individuals. Conclusion: Physiological adjustments, including the hematological system, stress hormones, and lipid molecules contributed to early altitude acclimatization, and showed strong correlations with cmiRNA reprogramming. Moreover, acclimatized and un-acclimatized individuals showed different cmiRNA profile. Suppression of the HIF-1 signaling pathway by microRNA regulation may play a key role in the pathogenesis of un-acclimatization with high altitude hypoxia. PMID:27994555

The effect on engine performance of change in jacket-water outlet temperature

NASA Technical Reports Server (NTRS)

Garlock, E A; Ellis, Greer

1933-01-01

Tests made on a Curtiss D-12 engine in the Altitude Laboratory at the Bureau of Standards show the following effects on engine performance of change in jacket-water outlet temperature: 1) Friction at all altitudes is a linear function of the jacket-water temperature, decreasing with increasing temperature. 2) The brake horsepower below an altitude of about 9,000 feet decreases, and at higher altitudes increases, with jacket-water temperature. 3) The brake specific fuel consumption tends to decrease, at all altitudes, with increasing jacket-water temperature. 4) The percentage change in brake power output is roughly equal to the algebraic sum of the percentage change in volumetric efficiency and mechanical efficiency.

High altitude illness

PubMed

Hartman-Ksycińska, Anna; Kluz-Zawadzka, Jolanta; Lewandowski, Bogumił

High-altitude illness is a result of prolonged high-altitude exposure of unacclimatized individuals. The illness is seen in the form of acute mountain sickness (AMS) which if not treated leads to potentially life-threatening high altitude pulmonary oedema and high-altitude cerebral oedema. Medical problems are caused by hypobaric hypoxia stimulating hypoxia-inducible factor (HIF) release. As a result, the central nervous system, circulation and respiratory system function impairment occurs. The most important factor in AMS treatment is acclimatization, withdrawing further ascent and rest or beginning to descent; oxygen supplementation, and pharmacological intervention, and, if available, a portable hyperbaric chamber. Because of the popularity of high-mountain sports and tourism better education of the population at risk is essential.

Aeronautic Instruments. Section II : Altitude Instruments

NASA Technical Reports Server (NTRS)

Mears, A H; Henrickson, H B; Brombacher, W G

1923-01-01

This report is Section two of a series of reports on aeronautic instruments (Technical Report nos. 125 to 132, inclusive). This section discusses briefly barometric altitude determinations, and describes in detail the principal types of altimeters and barographs used in aeronautics during the recent war. This is followed by a discussion of performance requirements for such instruments and an account of the methods of testing developed by the Bureau of Standards. The report concludes with a brief account of the results of recent investigations. For accurate measurements of altitude, reference must also be made to thermometer readings of atmospheric temperature, since the altitude is not fixed by atmospheric pressure alone. This matter is discussed in connection with barometric altitude determination.

Altitude and configuration of the potentiometric surface in the Triassic sandstones and shales, northeastern Chester County, Pennsylvania, September 1987 through January 1988

USGS Publications Warehouse

Senior, Lisa A.; Garges, John A.

1989-01-01

The altitude of the water levels in the Triassic sandstones and shales in northeastern Chester County is shown on a map at a scale of 1:24,000. The map is based on water levels in 173 non-pumping drilled and dug wells measured in 1956 and 1965, and on the altitude of two springs that were flowing in November and December 1987. Water level altitudes are contoured at an interval of 20 ft. The surface defined by the contoured water levels may approximately represent the water table. Water table altitudes range from 379 ft to less than 80 ft above sea level. (USGS)

Analysis of Experimental Sea-level Transient Data and Analog Method of Obtaining Altitude Response for Turbine-propeller Engine with Relay-type Speed Control

NASA Technical Reports Server (NTRS)

Vasu, George; Pack, George J

1951-01-01

Correlation has been established between transient engine and control data obtained experimentally and data obtained by simulating the engine and control with an analog computer. This correlation was established at sea-level conditions for a turbine-propeller engine with a relay-type speed control. The behavior of the controlled engine at altitudes of 20,000 and 35,000 feet was determined with an analog computer using the altitude pressure and temperature generalization factors to calculate the new engine constants for these altitudes. Because the engine response varies considerably at altitude some type of compensation appears desirable and four methods of compensation are discussed.

Application of trajectory optimization techniques to upper atmosphere sampling flights using the F4-C Phantom aircraft

NASA Technical Reports Server (NTRS)

Hague, D. S.; Merz, A. W.

1975-01-01

Altitude potential of an off-the-shelf F4-C aircraft is examined. It is shown that the standard F4-C has a maximum altitude capability in the region from 85000 to 95000 ft, depending on the minimum dynamic pressures deemed acceptable for adequate flight control. By using engine overspeed capability and by making use of prevailing winds in the stratosphere, it is suggested that the maximum altitude achievable by an F4-C should be in the vicinity of 95000 ft for routine flight operation. This altitude is well in excess of the minimum altitudes which must be achieved for monitoring the possible growth of suspected aerosol contaminants.

Autonomous Spacecraft Navigation Using Above-the-Constellation GPS Signals

NASA Technical Reports Server (NTRS)

Winternitz, Luke

2017-01-01

GPS-based spacecraft navigation offers many performance and cost benefits, and GPS receivers are now standard GNC components for LEO missions. Recently, more and more high-altitude missions are taking advantage of the benefits of GPS navigation as well. High-altitude applications pose challenges, however, because receivers operating above the GPS constellations are subject to reduced signal strength and availability, and uncertain signal quality. This presentation will present the history and state-of-the-art in high-altitude GPS spacecraft navigation, including early experiments, current missions and receivers, and efforts to characterize and protect signals available to high-altitude users. Recent results from the very-high altitude MMS mission are also provided.

Turbojet Performance and Operation at High Altitudes with Hydrogen and Jp-4 Fuels

NASA Technical Reports Server (NTRS)

Fleming, W A; Kaufman, H R; Harp, J L , Jr; Chelko, L J

1956-01-01

Two current turbojet engines were operated with gaseous-hydrogen and JP-4 fuels at very high altitudes and a simulated Mach number of 0.8. With gaseous hydrogen as the fuel stable operation was obtained at altitudes up to the facility limit of about 90,000 feet and the specific fuel consumption was only 40 percent of that with JP-4 fuel. With JP-4 as the fuel combustion was unstable at altitudes above 60,000 to 65,000 feet and blowout limits were reached at 75,000 to 80,000 feet. Over-all performance, component efficiencies, and operating range were reduced considerable at very high altitudes with both fuels.

Dosimetry of secondary cosmic radiation up to an altitude of 30 km.

PubMed

Wissmann, F; Burda, O; Khurana, S; Klages, T; Langner, F

2014-10-01

Dosimetric measurements in the field of secondary cosmic radiation were extensively made during the last years. Since the majority of these measurements were performed on-board passenger aircraft at altitudes between 10 and 12 km, measurements at higher altitudes are desirable for the verification of the legal dose assessment procedures for aircrew. A simple solution is to use a high-altitude balloon that reaches altitudes as high as 30 km. In this work, it is shown that the dose rate profile up to 30 km can be measured with acceptable uncertainties using a Si-detector. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Cloud-to-ground lightning activity in Colombia and the influence of topography

NASA Astrophysics Data System (ADS)

Aranguren, D.; López, J.; Inampués, J.; Torres, H.; Betz, H.

2017-02-01

Lightning activity on the Colombian mountains, where the altitude varies from 0 to more than 5000 MSL, is studied based on VLF/LF lightning detection data and using a 2012-2013 dataset. The influence of altitude is observed by evaluating cloud-to-ground lightning incidence at different altitude intervals. The relationship between ground flash density and altitude gradient vectors is studied. Results show a clear dependence of the flash density on elevation.

Altitude-dependent changes of directional hearing in mountaineers.

PubMed Central

Rosenberg, M E; Pollard, A J

1992-01-01

This study demonstrates apparent deterioration in the ability to localize sound associated with acute exposure to high altitude in ten subjects on three mountaineering expeditions. Furthermore, the auditory localization errors improved to sea level values after a period of acclimatization. Occurring at altitudes where overt neurological symptoms are not usually seen, impairment of sensory perception may explain the increase in accidental deaths associated with altitude exposure due to disorientation and misjudgment but before hypoxia is evident. PMID:1422652

Excitation of earth-ionosphere waveguide in the ELF and lower VLF bands by modulated ionospheric current. Technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Field, E.C.; Bloom, R.M.

1993-05-21

In this report the authors use the principal of reciprocity in conjunction with a full-wave propagation code to calculate ground-level fields excited by ionospheric currents modulated at frequencies between 50 and 100 Hz with HF heaters. Their results show the dependence on source orientation, altitude, and dimension and therefore pertain to experiments using the HIPAS or HAARP ionospheric heaters. In the end-fire mode, the waveguide excitation efficiency of an ELF HED in the ionosphere is up to 20 dB greater than for a ground-based antenna, provided its altitude does not exceed 80-to-90 km. The highest efficiency occurs for a sourcemore » altitude of around 70 km; if that altitude is raised to 100 km, the efficiency drops by about 20 dB in the day and 10 dB at night. That efficiency does not account for the greater conductivity modulation that might be achieved at altitudes greater than 70 km, however. The trade-off between the altitude dependencies of the excitation efficiency and maximum achievable modulation depends on the ERP of the HF heater, the optimum altitude increasing with increasing ERP. For HIPAS the best modulation altitude is around 70 km, whereas for HAARP there might be marginal value in modulating at attitudes as high as 100 Km. Ionospheric modification, Ionospheric currents, Ionospheric heating.« less

Men Traveling Away from Home Are More Likely to Bring Malaria into High Altitude Villages, Northwest Ethiopia

PubMed Central

Alemu, Kassahun; Worku, Alemayehu; Berhane, Yemane; Kumie, Abera

2014-01-01

Background Information about malaria risk factors at high altitudes is scanty. Understanding the risk factors that determine the risk of malaria transmission at high altitude villages is important to facilitate implementing sustainable malaria control and prevention programs. Methods An unmatched case control study was conducted among patients seeking treatment at health centers in high altitude areas. Either microscopy or rapid diagnostic tests were used to confirm the presence of plasmodium species. A generalized linear model was used to identify the predictors of malaria transmission in high altitude villages. Results Males (AOR = 3.11, 95%CI: 2.28, 4.23), and those who traveled away from the home in the previous month (AOR = 2.01, 95% CI: 1.56, 2.58) were strongly associated with presence of malaria in high altitude villages. Other significant factors, including agriculture in occupation (AOR = 1.41, 95% CI: 1.05, 1.93), plants used for fencing (AOR = 1.70, 95% CI: 1.18, 2.52) and forests near the house (AOR = 1.60, 95% CI: 1.15, 2.47), were found predictors for malaria in high altitude villages. Conclusion Travel outside of their home was an important risk of malaria infections acquisition. Targeting males who frequently travel to malarious areas can reduce malaria transmission risks in high altitude areas. PMID:24748159

Identification of novel serum peptide biomarkers for high-altitude adaptation: a comparative approach

PubMed Central

Yang, Juan; Li, Wenhua; Liu, Siyuan; Yuan, Dongya; Guo, Yijiao; Jia, Cheng; Song, Tusheng; Huang, Chen

2016-01-01

We aimed to identify serum biomarkers for screening individuals who could adapt to high-altitude hypoxia at sea level. HHA (high-altitude hypoxia acclimated; n = 48) and HHI (high-altitude hypoxia illness; n = 48) groups were distinguished at high altitude, routine blood tests were performed for both groups at high altitude and at sea level. Serum biomarkers were identified by comparing serum peptidome profiling between HHI and HHA groups collected at sea level. Routine blood tests revealed the concentration of hemoglobin and red blood cells were significantly higher in HHI than in HHA at high altitude. Serum peptidome profiling showed that ten significantly differentially expressed peaks between HHA and HHI at sea level. Three potential serum peptide peaks (m/z values: 1061.91, 1088.33, 4057.63) were further sequence identified as regions of the inter-α trypsin inhibitor heavy chain H4 fragment (ITIH4 347–356), regions of the inter-α trypsin inhibitor heavy chain H1 fragment (ITIH1 205–214), and isoform 1 of fibrinogen α chain precursor (FGA 588–624). Expression of their full proteins was also tested by ELISA in HHA and HHI samples collected at sea level. Our study provided a novel approach for identifying potential biomarkers for screening people at sea level who can adapt to high altitudes. PMID:27150491

Lung function among 9- to 10-year-old Tibetan and Han Chinese schoolchildren living at different altitudes in Tibet.

PubMed

Yangzong; Berntsen, Sveinung; Bjertness, Espen; Stigum, Hein; Gonggalanzi; Bianba; Nafstad, Per

2013-03-01

Tibetans have lived at high altitude longer than any other high-altitude population. Still little is known about their lung function and especially among children. This study compared lung function values of forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and forced expiratory flow at 50% of FVC (FEF50) in children living at various altitudes in Tibet and with different ancestries. A cross-sectional study of lung function was performed among 9-10-year-old native Tibetan and Han Chinese children living at 3700 meters above sea level, and among native Tibetan children living at 4300 meters above sea level. The adjusted FVC and FEV1 were significantly higher in Tibetan children living at 4300 m above sea level as compared to Tibetans living at 3700 m. Tibetans living at 3700 m had higher FVC and FEV1 than Han Chinese living at the same altitude. All Tibetan children had on average higher FEF50 than Han Chinese. Tibetan children living at an altitude of 4300 m had relatively higher lung function than those living at 3700 m, and there were differences in lung function between Tibetans and Han Chinese who live at the same altitude. It seems likely that genetic factors involved in long-term adaptation to high altitude and cultural attributes could have contributed to the study findings.

Exercise Capacity and Selected Physiological Factors by Ancestry and Residential Altitude: Cross-Sectional Studies of 9–10-Year-Old Children in Tibet

PubMed Central

Berntsen, Sveinung; Andersen, Lars Bo; Stigum, Hein; Ouzhuluobu; Nafstad, Per; Wu, Tianyi; Bjertness, Espen

2014-01-01

Abstract Bianba, Sveinung Bernsten, Lars Bo Andersen, Hein Stegum, Ouzhuluobu, Per Nafstad, Tianyi Wu, and Espen Bjertness. Exercise capacity and selected physiological factors by ancestry and residential altitude—Cross-sectional studies of 9–10-year-old children in Tibet. High Alt Med Biol. 15:162–169, 2014.—Aim: Several physiological compensatory mechanisms have enabled Tibetans to live and work at high altitude, including increased ventilation and pulmonary diffusion capacity, both of which serve to increase oxygen transport in the blood. The aim of the present study was to compare exercise capacity (maximal power output) and selected physiological factors (arterial oxygen saturation and heart rate at rest and during maximal exercise, resting hemoglobin concentration, and forced vital capacity) in groups of native Tibetan children living at different residential altitudes (3700 vs. 4300 m above sea level) and across ancestry (native Tibetan vs. Han Chinese children living at the same altitude of 3700 m). Methods: A total of 430 9–10-year-old native Tibetan children from Tingri (4300 m) and 406 native Tibetan- and 406 Han Chinese immigrants (77% lowland-born and 33% highland-born) from Lhasa (3700 m) participated in two cross-sectional studies. The maximal power output (Wmax) was assessed using an ergometer cycle. Results: Lhasa Tibetan children had a 20% higher maximal power output (watts/kg) than Tingri Tibetan and 4% higher than Lhasa Han Chinese. Maximal heart rate, arterial oxygen saturation at rest, lung volume, and arterial oxygen saturation were significantly associated with exercise capacity at a given altitude, but could not fully account for the differences in exercise capacity observed between ancestry groups or altitudes. Conclusions: The superior exercise capacity in native Tibetans vs. Han Chinese may reflect a better adaptation to life at high altitude. Tibetans at the lower residential altitude of 3700 m demonstrated a better exercise capacity than residents at a higher altitude of 4300 m when measured at their respective residential altitudes. Such altitude- or ancestry-related difference could not be fully attributed to the physiological factors measured. PMID:24836751

Evaluation of Floodplain Modifications to Reduce the Effect of Floods Using a Two-Dimensional Hydrodynamic Model of the Flint River at Albany, Georgia

USGS Publications Warehouse

Musser, Jonathan W.

2008-01-01

Potential flow characteristics of future flooding along a 4.8-mile reach of the Flint River in Albany, Georgia, were simulated using recent digital-elevation-model data and the U.S. Geological Survey finite-element surface-water modeling system for two-dimensional flow in the horizontal plane (FESWMS-2DH). The model was run at four water-surface altitudes at the Flint River at Albany streamgage (02352500): 181.5-foot (ft) altitude with a flow of 61,100 cubic feet per second (ft3/s), 184.5-ft altitude with a flow of 75,400 ft3/s, 187.5-ft altitude with a flow of 91,700 ft3/s, and 192.5-ft altitude with a flow of 123,000 ft3/s. The model was run to measure changes in inundated areas and water-surface altitudes for eight scenarios of possible modifications to the 4.8-mile reach on the Flint River. The eight scenarios include removing a human-made peninsula located downstream from Oglethorpe Boulevard, increasing the opening under the Oakridge Drive bridge, adding culverts to the east Oakridge Drive bridge approach, adding culverts to the east and west Oakridge Drive bridge approaches, adding an overflow across the oxbow north of Oakridge Drive, making the overflow into a channel, removing the Oakridge Drive bridge, and adding a combination of an oxbow overflow and culverts on both Oakridge Drive bridge approaches. The modeled inundation and water-surface altitude changes were mapped for use in evaluating the river modifications. The most effective scenario at reducing inundated area was the combination scenario. At the 187.5-ft altitude, the inundated area decreased from 4.24 square miles to 4.00 square miles. The remove-peninsula scenario was the least effective with a reduction in inundated area of less than 0.01 square miles. In all scenarios, the inundated area reduction increased with water-surface altitude, peaking at the 187.5-ft altitude. The inundated area reduction then decreased at the gage altitude of 192.5 ft.

The link between outgoing longwave radiation and the altitude at which a spaceborne lidar beam is fully attenuated

NASA Astrophysics Data System (ADS)

Vaillant de Guélis, Thibault; Chepfer, Hélène; Noel, Vincent; Guzman, Rodrigo; Dubuisson, Philippe; Winker, David M.; Kato, Seiji

2017-12-01

According to climate model simulations, the changing altitude of middle and high clouds is the dominant contributor to the positive global mean longwave cloud feedback. Nevertheless, the mechanisms of this longwave cloud altitude feedback and its magnitude have not yet been verified by observations. Accurate, stable, and long-term observations of a metric-characterizing cloud vertical distribution that are related to the longwave cloud radiative effect are needed to achieve a better understanding of the mechanism of longwave cloud altitude feedback. This study shows that the direct measurement of the altitude of atmospheric lidar opacity is a good candidate for the necessary observational metric. The opacity altitude is the level at which a spaceborne lidar beam is fully attenuated when probing an opaque cloud. By combining this altitude with the direct lidar measurement of the cloud-top altitude, we derive the effective radiative temperature of opaque clouds which linearly drives (as we will show) the outgoing longwave radiation. We find that, for an opaque cloud, a cloud temperature change of 1 K modifies its cloud radiative effect by 2 W m-2. Similarly, the longwave cloud radiative effect of optically thin clouds can be derived from their top and base altitudes and an estimate of their emissivity. We show with radiative transfer simulations that these relationships hold true at single atmospheric column scale, on the scale of the Clouds and the Earth's Radiant Energy System (CERES) instantaneous footprint, and at monthly mean 2° × 2° scale. Opaque clouds cover 35 % of the ice-free ocean and contribute to 73 % of the global mean cloud radiative effect. Thin-cloud coverage is 36 % and contributes 27 % of the global mean cloud radiative effect. The link between outgoing longwave radiation and the altitude at which a spaceborne lidar beam is fully attenuated provides a simple formulation of the cloud radiative effect in the longwave domain and so helps us to understand the longwave cloud altitude feedback mechanism.

Fertility in a high-altitude environment is compromised by luteal dysfunction: the relative roles of hypoxia and oxidative stress

PubMed Central

2013-01-01

Background At high altitudes, hypoxia, oxidative stress or both compromise sheep fertility. In the present work, we tested the relative effect of short- or long-term exposure to high altitude hypobaric hypoxia and oxidative stress on corpora luteal structure and function. Methods The growth dynamics of the corpora lutea during the estrous cycle were studied daily by ultrasonography in cycling sheep that were either native or naïve to high-altitude conditions and that were supplemented or not supplemented with antioxidant vitamins. Arterial and venous blood samples were simultaneously drawn for determination of gases and oxidative stress biomarkers and progesterone measurement. On day five after ovulation in the next cycle, the ovaries were removed for immunodetection of luteal HIF-1alpha and VEGF and IGF-I and to detect IGF-II gene expression. Results The results showed that both short- and long-term exposure to high-altitude conditions decreased luteal growth and IGF-I and IGF-II gene expression but increased HIF-1 alpha and VEGF immunoexpression. The level of plasma progesterone was also increased at a high altitude, although an association with increased corpus luteum vascularization was only found in sheep native to a high-altitude location. Administration of antioxidant vitamins resulted in a limited effect, which was restricted to decreased expression of oxidative stress biomarkers and luteal HIF-1alpha and VEGF immunoexpression. Conclusions Exposure of the sheep to high-altitude hypobaric hypoxia for short or long time periods affects the development and function of the corpus luteum. Moreover, the observed association of oxidative stress with hypoxia and the absence of any significant effect of antioxidant vitamins on most anatomical and functional corpus luteum traits suggests that the effects of high altitude on this ovarian structure are mainly mediated by hypoxia. Thus, these findings may help explain the decrease in sheep fertility at a high altitude. PMID:23521851

Effects of Positive Airway Pressure on Patients with Obstructive Sleep Apnea during Acute Ascent to Altitude

PubMed Central

Nishida, Katsufumi; Cloward, Tom V.; Weaver, Lindell K.; Brown, Samuel M.; Bell, James E.; Grissom, Colin K.

2015-01-01

Rationale: In acute ascent to altitude, untreated obstructive sleep apnea (OSA) is often replaced with central sleep apnea (CSA). In patients with obstructive sleep apnea who travel to altitude, it is unknown whether their home positive airway pressure (PAP) settings are sufficient to treat their obstructive sleep apnea, or altitude-associated central sleep apnea. Methods: Ten participants with positive airway pressure–treated obstructive sleep apnea, who reside at 1,320 m altitude, underwent polysomnography on their home positive airway pressure settings at 1,320 m and at a simulated altitude of 2,750 m in a hypobaric chamber. Six of the participants were subsequently studied without positive airway pressure at 2,750 m. Measurements and Main Results: At 1,320 m, all participants’ sleep apnea was controlled with positive airway pressure on home settings; at 2,750, no participants’ sleep apnea was controlled. At higher altitude, the apnea–hypopnea index was higher (11 vs. 2 events/h; P < 0.01), mostly due to hypopneas (10.5 vs. 2 events/h; P < 0.01). Mean oxygen saturations were lower (88 vs. 93%; P < 0.01) and total sleep time was diminished (349 vs. 393 min; P = 0.03). Four of six participants without positive airway pressure at 2,750 m required supplemental oxygen to prevent sustained oxygen saturation (as determined by pulse oximetry) less than 80%. Positive airway pressure also was associated with reduced central sleep apnea (0 vs. 1; P = 0.03), improved sleep time (358 vs. 292 min; P = 0.06), and improved sleep efficiency (78 vs. 63%; P = 0.04). Conclusions: Acute altitude exposure in patients with obstructive sleep apnea treated with positive airway pressure is associated with hypoxemia, decreased sleep time, and increased frequency of hypopneas compared with baseline altitude. Application of positive airway pressure at altitude is associated with decreased central sleep apnea and increased sleep efficiency. PMID:25884271

Domain Specific Changes in Cognition at High Altitude and Its Correlation with Hyperhomocysteinemia

PubMed Central

Sharma, Vijay K.; Das, Saroj K.; Dhar, Priyanka; Hota, Kalpana B.; Mahapatra, Bidhu B.; Vashishtha, Vivek; Kumar, Ashish; Hota, Sunil K.; Norboo, Tsering; Srivastava, Ravi B.

2014-01-01

Though acute exposure to hypobaric hypoxia is reported to impair cognitive performance, the effects of prolonged exposure on different cognitive domains have been less studied. The present study aimed at investigating the time dependent changes in cognitive performance on prolonged stay at high altitude and its correlation with electroencephalogram (EEG) and plasma homocysteine. The study was conducted on 761 male volunteers of 25–35 years age who had never been to high altitude and baseline data pertaining to domain specific cognitive performance, EEG and homocysteine was acquired at altitude ≤240 m mean sea level (MSL). The volunteers were inducted to an altitude of 4200–4600 m MSL and longitudinal follow-ups were conducted at durations of 03, 12 and 18 months. Neuropsychological assessment was performed for mild cognitive impairment (MCI), attention, information processing rate, visuo-spatial cognition and executive functioning. Total homocysteine (tHcy), vitamin B12 and folic acid were estimated. Mini Mental State Examination (MMSE) showed temporal increase in the percentage prevalence of MCI from 8.17% on 03 months of stay at high altitude to 18.54% on 18 months of stay. Impairment in visuo-spatial executive, attention, delayed recall and procedural memory related cognitive domains were detected following prolonged stay in high altitude. Increase in alpha wave amplitude in the T3, T4 and C3 regions was observed during the follow-ups which was inversely correlated (r = −0.68) to MMSE scores. The tHcy increased proportionately with duration of stay at high altitude and was correlated with MCI. No change in vitamin B12 and folic acid was observed. Our findings suggest that cognitive impairment is progressively associated with duration of stay at high altitude and is correlated with elevated tHcy in the plasma. Moreover, progressive MCI at high altitude occurs despite acclimatization and is independent of vitamin B12 and folic acid. PMID:24988417

Fertility in a high-altitude environment is compromised by luteal dysfunction: the relative roles of hypoxia and oxidative stress.

PubMed

Parraguez, Víctor H; Urquieta, Bessie; Pérez, Laura; Castellaro, Giorgio; De los Reyes, Mónica; Torres-Rovira, Laura; Aguado-Martínez, Adriana; Astiz, Susana; González-Bulnes, Antonio

2013-03-23

At high altitudes, hypoxia, oxidative stress or both compromise sheep fertility. In the present work, we tested the relative effect of short- or long-term exposure to high altitude hypobaric hypoxia and oxidative stress on corpora luteal structure and function. The growth dynamics of the corpora lutea during the estrous cycle were studied daily by ultrasonography in cycling sheep that were either native or naïve to high-altitude conditions and that were supplemented or not supplemented with antioxidant vitamins. Arterial and venous blood samples were simultaneously drawn for determination of gases and oxidative stress biomarkers and progesterone measurement. On day five after ovulation in the next cycle, the ovaries were removed for immunodetection of luteal HIF-1alpha and VEGF and IGF-I and to detect IGF-II gene expression. The results showed that both short- and long-term exposure to high-altitude conditions decreased luteal growth and IGF-I and IGF-II gene expression but increased HIF-1 alpha and VEGF immunoexpression. The level of plasma progesterone was also increased at a high altitude, although an association with increased corpus luteum vascularization was only found in sheep native to a high-altitude location. Administration of antioxidant vitamins resulted in a limited effect, which was restricted to decreased expression of oxidative stress biomarkers and luteal HIF-1alpha and VEGF immunoexpression. Exposure of the sheep to high-altitude hypobaric hypoxia for short or long time periods affects the development and function of the corpus luteum. Moreover, the observed association of oxidative stress with hypoxia and the absence of any significant effect of antioxidant vitamins on most anatomical and functional corpus luteum traits suggests that the effects of high altitude on this ovarian structure are mainly mediated by hypoxia. Thus, these findings may help explain the decrease in sheep fertility at a high altitude.

Iron supplementation at high altitudes induces inflammation and oxidative injury to lung tissues in rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salama, Samir A., E-mail: salama.3@buckeyemail.osu.edu; Department of Biochemistry, Faculty of Pharmacy, Al-Azhar University, Cairo 11751; Department of Pharmacology and GTMR Unit, College of Clinical Pharmacy, Taif University, Al-Haweiah, Taif 21974

2014-01-01

Exposure to high altitudes is associated with hypoxia and increased vulnerability to oxidative stress. Polycythemia (increased number of circulating erythrocytes) develops to compensate the high altitude associated hypoxia. Iron supplementation is, thus, recommended to meet the demand for the physiological polycythemia. Iron is a major player in redox reactions and may exacerbate the high altitudes-associated oxidative stress. The aim of this study was to explore the potential iron-induced oxidative lung tissue injury in rats at high altitudes (6000 ft above the sea level). Iron supplementation (2 mg elemental iron/kg, once daily for 15 days) induced histopathological changes to lung tissuesmore » that include severe congestion, dilatation of the blood vessels, emphysema in the air alveoli, and peribronchial inflammatory cell infiltration. The levels of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α), lipid peroxidation product and protein carbonyl content in lung tissues were significantly elevated. Moreover, the levels of reduced glutathione and total antioxidant capacity were significantly reduced. Co-administration of trolox, a water soluble vitamin E analog (25 mg/kg, once daily for the last 7 days of iron supplementation), alleviated the lung histological impairments, significantly decreased the pro-inflammatory cytokines, and restored the oxidative stress markers. Together, our findings indicate that iron supplementation at high altitudes induces lung tissue injury in rats. This injury could be mediated through excessive production of reactive oxygen species and induction of inflammatory responses. The study highlights the tissue injury induced by iron supplementation at high altitudes and suggests the co-administration of antioxidants such as trolox as protective measures. - Highlights: • Iron supplementation at high altitudes induced lung histological changes in rats. • Iron induced oxidative stress in lung tissues of rats at high altitudes. • Iron increased the levels of IL-1β, IL-6 and TNF-α in lung tissues at high altitudes. • Trolox alleviated the iron-induced histological and biochemical changes to the lungs.« less

Rhodiola crenulata- and Cordyceps sinensis-Based Supplement Boosts Aerobic Exercise Performance after Short-Term High Altitude Training

PubMed Central

Chen, Chung-Yu; Hou, Chien-Wen; Bernard, Jeffrey R.; Chen, Chiu-Chou; Hung, Ta-Cheng; Cheng, Lu-Ling; Liao, Yi-Hung

2014-01-01

Abstract Chen, Chung-Yu, Chien-Wen Hou, Jeffrey R. Bernard, Chiu-Chou Chen, Ta-Cheng Hung, Lu-Ling Cheng, Yi-Hung Liao, and Chia-Hua Kuo. Rhodiola crenulata- and Cordyceps sinensis-based supplement boosts aerobic exercise performance after short-term high altitude training. High Alt Med Biol 15:371–379, 2014.—High altitude training is a widely used strategy for improving aerobic exercise performance. Both Rhodiola crenulata (R) and Cordyceps sinensis (C) supplements have been reported to improve exercise performance. However, it is not clear whether the provision of R and C during high altitude training could further enhance aerobic endurance capacity. In this study, we examined the effect of R and C based supplementation on aerobic exercise capacity following 2-week high altitude training. Alterations to autonomic nervous system activity, circulatory hormonal, and hematological profiles were investigated. Eighteen male subjects were divided into two groups: Placebo (n=9) and R/C supplementation (RC, n=9). Both groups received either RC (R: 1400 mg+C: 600 mg per day) or the placebo during a 2-week training period at an altitude of 2200 m. After 2 weeks of altitude training, compared with Placebo group, the exhaustive run time was markedly longer (Placebo: +2.2% vs. RC: +5.7%; p<0.05) and the decline of parasympathetic (PNS) activity was significantly prevented in RC group (Placebo: −51% vs. RC: −41%; p<0.05). Red blood cell, hematocrit, and hemoglobin levels were elevated in both groups to a comparable extent after high altitude training (p<0.05), whereas the erythropoietin (EPO) level remained higher in the Placebo group (∼48% above RC values; p<0.05). The provision of an RC supplement during altitude training provides greater training benefits in improving aerobic performance. This beneficial effect of RC treatment may result from better maintenance of PNS activity and accelerated physiological adaptations during high altitude training. PMID:25251930

Right ventricular morphology and function in chronic obstructive pulmonary disease patients living at high altitude.

PubMed

Güvenç, Tolga Sinan; Erer, Hatice Betül; Kul, Seref; Perinçek, Gökhan; Ilhan, Sami; Sayar, Nurten; Yıldırım, Binnaz Zeynep; Doğan, Coşkun; Karabağ, Yavuz; Balcı, Bahattin; Eren, Mehmet

2013-01-01

Pulmonary vasculature is affected in patients with chronic pulmonary obstructive disease (COPD). As a result of increased pulmonary resistance, right ventricular morphology and function are altered in COPD patients. High altitude and related hypoxia causes pulmonary vasoconstriction, thereby affecting the right ventricle. We aimed to investigate the combined effects of COPD and altitude-related chronic hypoxia on right ventricular morphology and function. Forty COPD patients living at high altitude (1768 m) and 41 COPD patients living at sea level were enrolled in the study. All participants were diagnosed as COPD by a pulmonary diseases specialist depending on symptoms, radiologic findings and pulmonary function test results. Detailed two-dimensional echocardiography was performed by a cardiologist at both study locations. Oxygen saturation and mean pulmonary artery pressure were higher in the high altitude group. Right ventricular end diastolic diameter, end systolic diameter, height and end systolic area were significantly higher in the high altitude group compared to the sea level group. Parameters of systolic function, including tricuspid annular systolic excursion, systolic velocity of tricuspid annulus and right ventricular isovolumic acceleration were similar between groups, while fractional area change was significantly higher in the sea level groups compared to the high altitude group. Indices of diastolic function and myocardial performance index were similar between groups. An increase in mean pulmonary artery pressure and right ventricular dimensions are observed in COPD patients living at high altitude. Despite this increase, systolic and diastolic functions of the right ventricle, as well as global right ventricular performance are similar in COPD patients living at high altitude and sea level. Altitude-related adaptation to chronic hypoxia could explain these findings. Copyright © 2012 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

Changes in balance and joint position sense during a 12-day high altitude trek: The British Services Dhaulagiri medical research expedition.

PubMed

Clarke, Sarah B; Deighton, Kevin; Newman, Caroline; Nicholson, Gareth; Gallagher, Liam; Boos, Christopher J; Mellor, Adrian; Woods, David R; O'Hara, John P

2018-01-01

Postural control and joint position sense are essential for safely undertaking leisure and professional activities, particularly at high altitude. We tested whether exposure to a 12-day trek with a gradual ascent to high altitude impairs postural control and joint position sense. This was a repeated measures observational study of 12 military service personnel (28±4 years). Postural control (sway velocity measured by a portable force platform) during standing balance, a Sharpened Romberg Test and knee joint position sense were measured, in England (113m elevation) and at 3 research camps (3619m, 4600m and 5140m) on a 12-day high altitude trek in the Dhaulagiri region of Nepal. Pulse oximetry, and Lake Louise scores were also recorded on the morning and evening of each trek day. Data were compared between altitudes and relationships between pulse oximetry, Lake Louise score, and sway velocity were explored. Total sway velocity during standing balance with eyes open (p = 0.003, d = 1.9) and during Sharpened Romberg test with eyes open (p = 0.007, d = 1.6) was significantly greater at altitudes of 3619m and 5140m when compared with sea level. Anterior-posterior sway velocity during standing balance with eyes open was also significantly greater at altitudes of 3619m and 5140m when compared with sea level (p = 0.001, d = 1.9). Knee joint position sense was not altered at higher altitudes. There were no significant correlations between Lake Louise scores, pulse oximetry and postural sway. Despite a gradual ascent profile, exposure to 3619 m was associated with impairments in postural control without impairment in knee joint position sense. Importantly, these impairments did not worsen at higher altitudes of 4600 m or 5140 m. The present findings should be considered during future trekking expeditions when developing training strategies targeted to manage impairments in postural control that occur with increasing altitude.

Austrian Moderate Altitude Study (AMAS 2000) - fluid shifts, erythropoiesis, and angiogenesis in patients with metabolic syndrome at moderate altitude (congruent with 1700 m).

PubMed

Gunga, Hanns-Christian; Fries, Dietmar; Humpeler, Egon; Kirsch, Karl; Boldt, Leif-Erik; Koralewski, Eberhard; Johannes, Bernd; Klingler, Anton; Mittermayr, Markus; Röcker, Lothar; Yaban, Berrin; Behn, Claus; Jelkmann, Wolfgang; Schobersberger, Wolfgang

2003-02-01

It was hypothesized that subjects with metabolic syndrome (hypertension, obesity, hyperlipidemia, diabetes mellitus): (1) develop measurable peripheral edema at moderate altitude and (2) might show differences on erythropoiesis, iron status and vascular endothelial growth factor (VEGF) in comparison to healthy subjects during and after a long-term stay (3-week exposure) at moderate altitude (congruent with 1700 m). Twenty-two male subjects with metabolic syndrome were selected. Baseline investigations (t1) were performed in Innsbruck (500 m). All participants were transferred by bus to 1700 m (Alps) and remained there for 3 weeks with examinations on day 1 (after the first night at altitude, t2), day 4 (t3), day 9 (t4) and day 19 (t5). After returning to Innsbruck, post-altitude examinations were conducted after 7-10 days (t6) and 6-7 weeks (t7), respectively. Body mass was decreased from t1 to t7 (P<0.01). Total body water was decreased at t2 (P<0.01), returned to control level (t3, t4), and was found elevated at t7 (P<0.01). Lean body mass did not change, but body fat decreased during the study (P<0.01). Tissue thickness at the forehead decreased during and after altitude exposure (P<0.01), whereas tissue thickness at the tibia did not alter. Erythropoietin (EPO) was elevated as early as t2 and remained increased until t5. Reticulocyte count was increased at t3 and remained above pre-altitude values. VEGF levels were unchanged. After a 3-week exposure to moderate altitude, patients with metabolic syndrome had reduced their body mass, mainly because of a reduction in body fat. The moderate altitude was found to stimulate erythropoiesis in these patients but this was not sufficient to increase serum VEGF concentration.

Mole-rats from higher altitudes have greater thermoregulatory capabilities.

PubMed

Broekman, Marna; Bennett, Nigel C; Jackson, Craig R; Scantlebury, Michael

2006-12-30

Subterranean mammals (those that live and forage underground) inhabit a challenging microenvironment, with high levels of carbon dioxide and low levels of oxygen. Consequently, they have evolved specialised morphological and physiological adaptations. For small mammals that inhabit high altitudes, the effects of cold are compounded by low oxygen partial pressures. Hence, subterranean mammals living at high altitudes are faced with a uniquely demanding physiological environment, which presumably necessitates additional physiological adjustments. We examined the thermoregulatory capabilities of two populations of Lesotho mole-rat Cryptomys hottentotus mahali that inhabit a 'low' (1600 m) and a 'high' (3200 m) altitude. Mole-rats from the high altitude had a lower temperature of the lower critical point, a broader thermoneutral zone, a lower thermal conductance and greater regulatory non-shivering thermogenesis than animals from the lower altitude. However, minimum resting metabolic rate values were not significantly different between the populations and were low compared with allometric predictions. We suggest that thermoregulatory costs may in part be met by animals maintaining a low resting metabolic rate. High-altitude animals may adjust to their cooler, more oxygen-deficient environment by having an increased non-shivering thermogenesis whilst maintaining low thermal conductance.

Personal Cabin Pressure Monitor and Warning System

NASA Technical Reports Server (NTRS)

Zysko, Jan A. (Inventor)

2002-01-01

A cabin pressure altitude monitor and warning system provides a warning when a detected cabin pressure altitude has reached a predetermined level. The system is preferably embodied in a portable, pager-sized device that can be carried or worn by an individual. A microprocessor calculates the pressure altitude from signals generated by a calibrated pressure transducer and a temperature sensor that compensates for temperature variations in the signals generated by the pressure transducer. The microprocessor is programmed to generate a warning or alarm if a cabin pressure altitude exceeding a predetermined threshold is detected. Preferably, the microprocessor generates two different types of warning or alarm outputs, a first early warning or alert when a first pressure altitude is exceeded. and a second more serious alarm condition when either a second. higher pressure altitude is exceeded, or when the first pressure altitude has been exceeded for a predetermined period of time. Multiple types of alarm condition indicators are preferably provided, including visual, audible and tactile. The system is also preferably designed to detect gas concentrations and other ambient conditions, and thus incorporates other sensors, such as oxygen, relative humidity, carbon dioxide, carbon monoxide and ammonia sensors, to provide a more complete characterization and monitoring of the local environment.

Shape memory alloy resistance behaviour at high altitude for feedback control

NASA Astrophysics Data System (ADS)

Ng, W. T.; Sedan, M. F.; Abdullah, E. J.; Azrad, S.; Harithuddin, A. S. M.

2017-12-01

Many recent aerospace technologies are using smart actuators to reduce the system's complexity and increase its reliability. One such actuator is shape memory alloy (SMA) actuator, which is lightweight, produces high force and large deflection. However, some disadvantages in using SMA actuators have been identified and they include nonlinear response of the strain to input current, hysteresis characteristic that results in inaccurate control and less than optimum system performance, high operating temperatures, slow response and also high requirement of electrical power to obtain the desired actuation forces. It is still unknown if the SMA actuators can perform effectively at high altitude with low surrounding temperature. The work presented here covers the preliminary process of verifying the feasibility of using resistance as feedback control at high altitude for aerospace applications. Temperature and resistance of SMA actuator at high altitude is investigated by conducting an experiment onboard a high altitude balloon. The results from the high altitude experiment indicate that the resistance or voltage drop of the SMA wire is not significantly affected by the low surrounding temperature at high altitude as compared to the temperature of SMA. Resistance feedback control for SMA actuators may be suitable for aerospace applications.

Shilajit: A panacea for high-altitude problems

PubMed Central

Meena, Harsahay; Pandey, H. K.; Arya, M. C.; Ahmed, Zakwan

2010-01-01

High altitude problems like hypoxia, acute mountain sickness, high altitude cerebral edema, pulmonary edema, insomnia, tiredness, lethargy, lack of appetite, body pain, dementia, and depression may occur when a person or a soldier residing in a lower altitude ascends to high-altitude areas. These problems arise due to low atmospheric pressure, severe cold, high intensity of solar radiation, high wind velocity, and very high fluctuation of day and night temperatures in these regions. These problems may escalate rapidly and may sometimes become life-threatening. Shilajit is a herbomineral drug which is pale-brown to blackish-brown, is composed of a gummy exudate that oozes from the rocks of the Himalayas in the summer months. It contains humus, organic plant materials, and fulvic acid as the main carrier molecules. It actively takes part in the transportation of nutrients into deep tissues and helps to overcome tiredness, lethargy, and chronic fatigue. Shilajit improves the ability to handle high altitudinal stresses and stimulates the immune system. Thus, Shilajit can be given as a supplement to people ascending to high-altitude areas so that it can act as a “health rejuvenator” and help to overcome high-altitude related problems. PMID:20532096

Shilajit: A panacea for high-altitude problems.

PubMed

Meena, Harsahay; Pandey, H K; Arya, M C; Ahmed, Zakwan

2010-01-01

High altitude problems like hypoxia, acute mountain sickness, high altitude cerebral edema, pulmonary edema, insomnia, tiredness, lethargy, lack of appetite, body pain, dementia, and depression may occur when a person or a soldier residing in a lower altitude ascends to high-altitude areas. These problems arise due to low atmospheric pressure, severe cold, high intensity of solar radiation, high wind velocity, and very high fluctuation of day and night temperatures in these regions. These problems may escalate rapidly and may sometimes become life-threatening. Shilajit is a herbomineral drug which is pale-brown to blackish-brown, is composed of a gummy exudate that oozes from the rocks of the Himalayas in the summer months. It contains humus, organic plant materials, and fulvic acid as the main carrier molecules. It actively takes part in the transportation of nutrients into deep tissues and helps to overcome tiredness, lethargy, and chronic fatigue. Shilajit improves the ability to handle high altitudinal stresses and stimulates the immune system. Thus, Shilajit can be given as a supplement to people ascending to high-altitude areas so that it can act as a "health rejuvenator" and help to overcome high-altitude related problems.

Personal Cabin Pressure Monitor and Warning System

NASA Astrophysics Data System (ADS)

Zysko, Jan A.

2002-09-01

A cabin pressure altitude monitor and warning system provides a warning when a detected cabin pressure altitude has reached a predetermined level. The system is preferably embodied in a portable, pager-sized device that can be carried or worn by an individual. A microprocessor calculates the pressure altitude from signals generated by a calibrated pressure transducer and a temperature sensor that compensates for temperature variations in the signals generated by the pressure transducer. The microprocessor is programmed to generate a warning or alarm if a cabin pressure altitude exceeding a predetermined threshold is detected. Preferably, the microprocessor generates two different types of warning or alarm outputs, a first early warning or alert when a first pressure altitude is exceeded. and a second more serious alarm condition when either a second. higher pressure altitude is exceeded, or when the first pressure altitude has been exceeded for a predetermined period of time. Multiple types of alarm condition indicators are preferably provided, including visual, audible and tactile. The system is also preferably designed to detect gas concentrations and other ambient conditions, and thus incorporates other sensors, such as oxygen, relative humidity, carbon dioxide, carbon monoxide and ammonia sensors, to provide a more complete characterization and monitoring of the local environment.

Changes in transthoracic electrical impedance at high altitude.

PubMed

Hoon, R S; Balasubramanian, V; Tiwari, S C; Mathew, O P; Behl, A; Sharma, S C; Chadha, K S

1977-01-01

Mean transthoracic electrical impedance (impedance) which is inversely related to intrathoracic extravascular fluid volume was measured in 121 normal healthy volunteers at sea-level and at 3658 metres altitude. Fifty (group A) reached the high altitude location after an hour's journey in a pressurised aircraft. Twenty-five (group D) underwent slow road ascent including acclimatisation en route. Thirty permanent residents (group B) and 16 temporary residents at high altitude (group C) were also studied. Serial studies in the 30 subjects of group A who developed symptoms of high altidue sickness showed a significant decrease of impedance up to the fourth day of exposure to high altitude which later returned to normal. The 4 volunteers who developed severe symptoms showed the largest drop in impedance. A case of acute pulmonary oedema developing at 4300 metres showed an impedance value of 24-1 ohms on admission. After effective treatment the impedance increased by 11-9 to 36-0 ohms. Twenty asymptomatic subjects of group A and 25 of group D showed a small average increase in impedance values at high altitude. These obstructions suggest that measurement of transthoracic electrical impedance may be a valuable means of detecting incipient high altitude pulmonary oedema.

The Gravity Field of Mercury After the Messenger Low-Altitude Campaign

NASA Technical Reports Server (NTRS)

Mazarico, Erwan; Genova, Antonio; Goossens, Sander; Lemoine, Frank G.; Smith, David E.; Zuber, Maria T.; Neumann, Gary A.; Solomon, Sean C.

2015-01-01

The final year of the MESSENGER mission was designed to take advantage of the remaining propellant onboard to provide a series of lowaltitude observation campaigns and acquire novel scientific data about the innermost planet. The lower periapsis altitude greatly enhances the sensitivity to the short-wavelength gravity field, but only when the spacecraft is in view of Earth. After more than 3 years in orbit around Mercury, the MESSENGER spacecraft was tracked for the first time below 200-km altitude on 5 May 2014 by the NASA Deep Space Network (DSN). Between August and October, periapsis passages down to 25-km altitude were routinely tracked. These periods considerably improved the quality of the data coverage. Before the end of its mission, MESSENGER will fly at very low altitudes for extended periods of time. Given the orbital geometry, however the periapses will not be visible from Earth and so no new tracking data will be available for altitudes lower than 75 km. Nevertheless, the continuous tracking of MESSENGER in the northern hemisphere will help improve the uniformity of the spatial coverage at altitudes lower than 150 km, which will further improve the overall quality of the Mercury gravity field.

Spectral reflectance characteristics and automated data reduction techniques which identify wetland and water quality conditions in the Chesapeake Bay

NASA Technical Reports Server (NTRS)

Anderson, R. R.

1970-01-01

Progress on research designed to test the usability of multispectral, high altitude, remotely sensed data to analyze ecological and hydrological conditions in estuarine environments is presented. Emphasis was placed on data acquired by NASA aircraft over the Patuxent River Chesapeake Bay Test Site, No. 168. Missions were conducted over the Chesapeake Bay at a high altitude flight of 18,460 m and a low altitude flight of 3070. The principle objectives of the missions were: (1) to determine feasibility of identifying source and extent of water pollution problems in Baltimore Harbor, Chesapeake Bay and major tributaries utilizing high altitude, ERTS analogous remote sensing data; (2) to determine the feasibility of mapping species composition and general ecological condition of Chesapeake Bay wetlands, utilizing high altitude, ERTS analogous data; (3) to correlate ground spectral reflectance characteristics of wetland plant species with tonal characteristics on multispectral photography; (4) to determine usefulness of high altitude thermal imagery in delinating isotherms and current patterns in the Chesapeake Bay; and (5) to investigate automated data interpretive techniques which may be usable on high altitude, ERTS analogous data.

Measurement of Altitude in Blind Flying

NASA Technical Reports Server (NTRS)

Brombacher, W G

1934-01-01

In this note, instruments for measuring altitude and rate of change of altitude in blind flying and landing of aircraft and their performance are discussed. Of those indicating the altitude above ground level, the sonic altimeter is the most promising. Its present bulk, intermittent operation, and more or less unsatisfactory means of indication are serious drawbacks to its use. The sensitive type aneroid altimeter is also discussed and errors in flying at a pressure level and in landing are discussed in detail.

Observation of radio-wave-induced red hydroxyl emission at low altitude in the ionosphere.

PubMed

Kagan, L M; Nicolls, M J; Kelley, M C; Carlson, H C; Belikovich, V V; Bakhmet'eva, N V; Komrakov, G P; Trondsen, T S; Donovan, E

2005-03-11

We report the discovery of radio-wave-induced red emission of OH Meinel rotation-vibrational bands at 629.79 nm. These are the first measurements of artificial aurora below 100 km. We believe that the 629.79-nm OH emission was due to radio-wave focusing by sporadic ionization clouds near 80-85 km altitude, thus giving a technique to visualize the low-altitude sporadic ionization and providing insight into ionospheric interactions at these low altitudes.

Application of trajectory optimization techniques to upper atmosphere sampling flights using the F-15 Eagle aircraft

NASA Technical Reports Server (NTRS)

Hague, D. S.; Merz, A. W.

1976-01-01

Atmospheric sampling has been carried out by flights using an available high-performance supersonic aircraft. Altitude potential of an off-the-shelf F-15 aircraft is examined. It is shown that the standard F-15 has a maximum altitude capability in excess of 100,000 feet for routine flight operation by NASA personnel. This altitude is well in excess of the minimum altitudes which must be achieved for monitoring the possible growth of suspected aerosol contaminants.

The Effects of a 10-day Altitude Training Camp at 1828 Meters on Varsity Cross-Country Runners

PubMed Central

DIEBEL, SEBASTIAN R.; NEWHOUSE, IAN; THOMPSON, DAVID S.; JOHNSON, VINEET B.K.

2017-01-01

Altitude training has been shown to alter blood lactate (BL) levels due to alterations resulting from acclimatization. This study aims to estimate the impact of altitude training on BL changes immediately following an incremental treadmill test and during recovery before and after 10-day altitude training at approximately 1828 meters. Eight varsity cross-country runners performed an incremental treadmill test (ITT), pre and post-altitude training. Resting and post-warm-up BL values were recorded. During ITT, heart rate (HR), oxygen saturation (SpO2), and time to exhaustion were monitored. BL was also measured post-ITT at 0, 2, 4, 6, and 8 minutes. The average of all BL values was higher following altitude intervention (8.8 ± 4.6 mmol/L) compared to pre-intervention (7.4 ± 3.3 mmol/L). These differences were statistically significant (t(6) = −2.40, p = .026). BL immediately (0 minutes) after the ITT was higher following the altitude intervention (13.6 ± 3.6 mmol/L) compared to pre-intervention (9.7 ± 3.8 mmol/L) and was statistically significant (t(7) = −3.30, p = .006). Average HR during the ITT was lower following the altitude intervention (176.9 ± 11.1 bpm) compared to pre (187 ± 9.5 bpm), these differences were statistically significant (t(28)= 18.07, p= <.001. Time to exhaustion was longer after the intervention, however was not statistically significant p = 0.13. These findings indicate that a 10 - day altitude intervention at 1828 meters may benefit varsity cross-country runners. The higher post-exercise BL may be attributed to more anaerobic contributions. Lower HR may suggest a larger stroke volume and/or more efficient O2 carrying capacity. PMID:28479950

Managing endotracheal tube cuff pressure at altitude: a comparison of four methods.

PubMed

Britton, Tyler; Blakeman, Thomas C; Eggert, John; Rodriquez, Dario; Ortiz, Heather; Branson, Richard D

2014-09-01

Ascent to altitude results in the expansion of gases in closed spaces. The management of overinflation of the endotracheal tube (ETT) cuff at altitude is critical to prevent mucosal injury. We continuously measured ETT cuff pressures during a Critical Care Air Transport Team training flight to 8,000-ft cabin pressure using four methods of cuff pressure management. ETTs were placed in a tracheal model, and mechanical ventilation was performed. In the control ETT, the cuff was inflated to 20 mm Hg to 22 mm Hg and not manipulated. The manual method used a pressure manometer to adjust pressure at cruising altitude and after landing. A PressureEasy device was connected to the pilot balloon of the third tube and set to a pressure of 20 mm Hg to 22 mm Hg. The final method filled the balloon with 10 mL of saline. Both size 8.0-mm and 7.5-mm ETT were studied during three flights. In the control tube, pressure exceeded 70 mm Hg at cruising altitude. Manual management corrected for pressure at altitude but resulted in low cuff pressures upon landing (<10 mm Hg). The PressureEasy reduced the pressure change to a maximum of 36 mm Hg, but on landing, cuff pressures were less than 15 mm Hg. Saline inflation ameliorated cuff pressure changes at altitude, but initial pressures were 40 mm Hg. None of the three methods using air inflation managed to maintain cuff pressures below those associated with tracheal damage at altitude or above pressures associated with secretion aspiration during descent. Saline inflation minimizes altitude-related alteration in cuff pressure but creates excessive pressures at sea level. New techniques need to be developed.

High‐altitude ancestry protects against hypoxia‐associated reductions in fetal growth

PubMed Central

Julian, Colleen Glyde; Vargas, Enrique; Armaza, J Fernando; Wilson, Megan J; Niermeyer, Susan; Moore, Lorna G

2007-01-01

Objective The chronic hypoxia of high‐altitude (⩾2500 m) residence has been shown to decrease birth weight in all populations studied to date. However, multigenerational high‐altitude populations appear protected relative to newcomer groups. This study aimed to determine whether such protection exists independently of other factors known to influence fetal growth and whether admixed populations (ie, people having both high‐ and low‐altitude ancestry) show an intermediate level of protection. Design 3551 medical records from consecutive deliveries to Andean, European or Mestizo (ie, admixed) women at low, intermediate or high altitudes in Bolivia were evaluated for maternal characteristics influencing fetal growth as measured by birth weight and the frequency of small for gestational age births (SGA or ⩽10th percentile birth weight for gestational age and sex). Two‐way analysis of variance and χ2 tests were used to compare maternal and infant characteristics. The effects of ancestry or altitude on SGA and birth weight were assessed using logistic or linear regression models, respectively. Results Altitude decreased birth weight and increased SGA in all ancestry groups. Andean infants weighed more and were less often SGA than Mestizo or European infants at high altitude (13%, 16% and 33% respectively, p<0.01). After accounting for the influences of maternal hypertensive complications of pregnancy, parity, body weight, and number of prenatal visits, European relative to Andean ancestry increased the frequency of SGA at high altitude nearly fivefold. Conclusions Andean relative to European ancestry protects against altitude‐associated reductions in fetal growth. The intermediate protection seen in the admixed (Mestizo) group is consistent with the influence of genetic or other Andean‐specific protective characteristics. PMID:17329275

Adaptation of the Long-Lived Monocarpic Perennial Saxifraga longifolia to High Altitude1[OPEN

PubMed Central

Morales, Melanie; Fleta-Soriano, Eva; Garcia, Maria B.

2016-01-01

Global change is exerting a major effect on plant communities, altering their potential capacity for adaptation. Here, we aimed at unveiling mechanisms of adaptation to high altitude in an endemic long-lived monocarpic, Saxifraga longifolia, by combining demographic and physiological approaches. Plants from three altitudes (570, 1100, and 2100 m above sea level [a.s.l.]) were investigated in terms of leaf water and pigment contents, and activation of stress defense mechanisms. The influence of plant size on physiological performance and mortality was also investigated. Levels of photoprotective molecules (α-tocopherol, carotenoids, and anthocyanins) increased in response to high altitude (1100 relative to 570 m a.s.l.), which was paralleled by reduced soil and leaf water contents and increased ABA levels. The more demanding effect of high altitude on photoprotection was, however, partly abolished at very high altitudes (2100 m a.s.l.) due to improved soil water contents, with the exception of α-tocopherol accumulation. α-Tocopherol levels increased progressively at increasing altitudes, which paralleled with reductions in lipid peroxidation, thus suggesting plants from the highest altitude effectively withstood high light stress. Furthermore, mortality of juveniles was highest at the intermediate population, suggesting that drought stress was the main environmental driver of mortality of juveniles in this rocky plant species. Population structure and vital rates in the high population evidenced lower recruitment and mortality in juveniles, activation of clonal growth, and absence of plant size-dependent mortality. We conclude that, despite S. longifolia has evolved complex mechanisms of adaptation to altitude at the cellular, whole-plant and population levels, drought events may drive increased mortality in the framework of global change. PMID:27440756

Influence of high altitude on the burning behaviour of typical combustibles and the related responses of smoke detectors in compartments

PubMed Central

Zeng, Yi; Fang, Jun; Zhang, Yong-Ming

2018-01-01

The effect of altitude on typical combustible burning and related smoke detector response signals was investigated by comparison experiments at altitudes of 40 m and 3650 m based on EN54 standard tests. Point-type light scattering photoelectric smoke detectors and ionization smoke detectors were used for four kinds of EN54 fire tests, including two kinds of smouldering fires with wood (test fire no. 2 in EN54 standard or TF2) and cotton (TF3), and two kinds of flaming fires with polyurethane (TF4) and n-heptane (TF5). First, the influence of altitude or ambient pressure on mass loss for smouldering combustion (TF2 or TF3) was insignificant, while a significant decrease in the mass burning rate was found for flaming tests (TF4 and TF5) as reported in our previous studies. Second, for photoelectric smoke detectors in flaming fire tests, the effect of altitude was similar to that of the burning rate, whereas for the ionization smoke detectors, the response signal at high altitudes was shown to be ‘enhanced’ by the detection principle of the ionization chamber, leading to an even larger value than at normal altitude for smouldering conditions. Third, to provide a reference for smoke detector design in high-altitude areas, the differences between signal speed in rising and peak values at two locations are discussed. Also, relationship between ion chamber signals and smoke optical densities are presented by utilization of an ionization smoke detector and smoke concentration meter. Moreover, a hierarchical diagram is illustrated to provide a better understanding of the effects of altitude on combustible burning behaviour and the mechanisms of detector response. PMID:29765695

Influence of high altitude on the burning behaviour of typical combustibles and the related responses of smoke detectors in compartments.

PubMed

Tu, Ran; Zeng, Yi; Fang, Jun; Zhang, Yong-Ming

2018-04-01

The effect of altitude on typical combustible burning and related smoke detector response signals was investigated by comparison experiments at altitudes of 40 m and 3650 m based on EN54 standard tests. Point-type light scattering photoelectric smoke detectors and ionization smoke detectors were used for four kinds of EN54 fire tests, including two kinds of smouldering fires with wood (test fire no. 2 in EN54 standard or TF2) and cotton (TF3), and two kinds of flaming fires with polyurethane (TF4) and n -heptane (TF5). First, the influence of altitude or ambient pressure on mass loss for smouldering combustion (TF2 or TF3) was insignificant, while a significant decrease in the mass burning rate was found for flaming tests (TF4 and TF5) as reported in our previous studies. Second, for photoelectric smoke detectors in flaming fire tests, the effect of altitude was similar to that of the burning rate, whereas for the ionization smoke detectors, the response signal at high altitudes was shown to be 'enhanced' by the detection principle of the ionization chamber, leading to an even larger value than at normal altitude for smouldering conditions. Third, to provide a reference for smoke detector design in high-altitude areas, the differences between signal speed in rising and peak values at two locations are discussed. Also, relationship between ion chamber signals and smoke optical densities are presented by utilization of an ionization smoke detector and smoke concentration meter. Moreover, a hierarchical diagram is illustrated to provide a better understanding of the effects of altitude on combustible burning behaviour and the mechanisms of detector response.

Nasal variation in relation to high-altitude adaptations among Tibetans and Andeans.

PubMed

Butaric, Lauren N; Klocke, Ross P

2018-05-01

High-altitude (>2500 m) populations face several pressures, including hypoxia and cold-dry air, resulting in greater respiratory demand to obtain more oxygen and condition inspired air. While cardiovascular and pulmonary adaptations to high-altitude hypoxia have been extensively studied, adaptations of upper-respiratory structures, e.g., nasal cavity, remain untested. This study investigates whether nasal morphology presents adaptations to hypoxic (larger noses) and/or cold-dry (tall/narrow noses) conditions among high-altitude samples. CT scans of two high- and four low-altitude samples from diverse climates were collected (n = 130): high-altitude Tibetans and Peruvians; low-altitude Peruvians, Southern Chinese (temperate), Mongolian-Buriats (cold-dry), and Southeast Asians (hot-wet). Facial and nasal distances were calculated from 3D landmarks placed on digitally-modeled crania. Temperature, precipitation, and barometric pressure data were also obtained. Principal components analysis and analyses of variance primarily indicate size-related differences among the cold-dry (Mongolian-Buriats) and hot-wet (Southeast Asians) adapted groups. Two-block partial least squares (PLS) analysis show weak relationships between size-standardized nasal dimensions and environmental variables. However, among PLS1 (85.90% of covariance), Tibetans display relatively larger nasal cavities related to lower temperatures and barometric pressure; regression analyses also indicate high-altitude Tibetans possess relatively larger internal nasal breadths and heights for their facial size. Overall, nasal differences relate to climate among the cold-dry and hot-wet groups. Specific nasal adaptations were not identified among either Peruvian group, perhaps due to their relatively recent migration history and population structure. However, high-altitude Tibetans seem to exhibit a compromise in nasal morphology, serving in increased oxygen uptake, and air-conditioning processes. © 2018 Wiley Periodicals, Inc.

Adaptation of the Long-Lived Monocarpic Perennial Saxifraga longifolia to High Altitude.

PubMed

Munné-Bosch, Sergi; Cotado, Alba; Morales, Melanie; Fleta-Soriano, Eva; Villellas, Jesús; Garcia, Maria B

2016-10-01

Global change is exerting a major effect on plant communities, altering their potential capacity for adaptation. Here, we aimed at unveiling mechanisms of adaptation to high altitude in an endemic long-lived monocarpic, Saxifraga longifolia, by combining demographic and physiological approaches. Plants from three altitudes (570, 1100, and 2100 m above sea level [a.s.l.]) were investigated in terms of leaf water and pigment contents, and activation of stress defense mechanisms. The influence of plant size on physiological performance and mortality was also investigated. Levels of photoprotective molecules (α-tocopherol, carotenoids, and anthocyanins) increased in response to high altitude (1100 relative to 570 m a.s.l.), which was paralleled by reduced soil and leaf water contents and increased ABA levels. The more demanding effect of high altitude on photoprotection was, however, partly abolished at very high altitudes (2100 m a.s.l.) due to improved soil water contents, with the exception of α-tocopherol accumulation. α-Tocopherol levels increased progressively at increasing altitudes, which paralleled with reductions in lipid peroxidation, thus suggesting plants from the highest altitude effectively withstood high light stress. Furthermore, mortality of juveniles was highest at the intermediate population, suggesting that drought stress was the main environmental driver of mortality of juveniles in this rocky plant species. Population structure and vital rates in the high population evidenced lower recruitment and mortality in juveniles, activation of clonal growth, and absence of plant size-dependent mortality. We conclude that, despite S. longifolia has evolved complex mechanisms of adaptation to altitude at the cellular, whole-plant and population levels, drought events may drive increased mortality in the framework of global change. © 2016 American Society of Plant Biologists. All Rights Reserved.

Lower Obesity Rate during Residence at High Altitude among a Military Population with Frequent Migration: A Quasi Experimental Model for Investigating Spatial Causation

PubMed Central

Voss, Jameson D.; Allison, David B.; Webber, Bryant J.; Otto, Jean L.; Clark, Leslie L.

2014-01-01

We sought to evaluate whether residence at high altitude is associated with the development of obesity among those at increased risk of becoming obese. Obesity, a leading global health priority, is often refractory to care. A potentially novel intervention is hypoxia, which has demonstrated positive long-term metabolic effects in rats. Whether or not high altitude residence confers benefit in humans, however, remains unknown. Using a quasi-experimental, retrospective study design, we observed all outpatient medical encounters for overweight active component enlisted service members in the U.S. Army or Air Force from January 2006 to December 2012 who were stationed in the United States. We compared high altitude (>1.96 kilometers above sea level) duty assignment with low altitude (<0.98 kilometers). The outcome of interest was obesity related ICD-9 codes (278.00-01, V85.3x-V85.54) by Cox regression. We found service members had a lower hazard ratio (HR) of incident obesity diagnosis if stationed at high altitude as compared to low altitude (HR 0.59, 95% confidence interval [CI] 0.54–0.65; p<0.001). Using geographic distribution of obesity prevalence among civilians throughout the U.S. as a covariate (as measured by the Centers for Disease Control and Prevention and the REGARDS study) also predicted obesity onset among service members. In conclusion, high altitude residence predicts lower rates of new obesity diagnoses among overweight service members in the U.S. Army and Air Force. Future studies should assign exposure using randomization, clarify the mechanism(s) of this relationship, and assess the net balance of harms and benefits of high altitude on obesity prevention. PMID:24740173

Relationship between changes in haemoglobin mass and maximal oxygen uptake after hypoxic exposure.

PubMed

Saunders, Philo U; Garvican-Lewis, Laura A; Schmidt, Walter F; Gore, Christopher J

2013-12-01

Endurance athletes have been using altitude training for decades to improve near sea-level performance. The predominant mechanism is thought to be accelerated erythropoiesis increasing haemoglobin mass (Hb(mass)) resulting in a greater maximal oxygen uptake (VO₂(max)). Not all studies have shown a proportionate increase in VO₂(max) as a result of increased Hb(mass). The aim of this study was to determine the relationship between the two parameters in a large group of endurance athletes after altitude training. 145 elite endurance athletes (94 male and 51 female) who participated in various altitude studies as altitude or control participants were used for the analysis. Participants performed Hb(mass) and VO₂(max) testing before and after intervention. For the pooled data, the correlation between per cent change in Hb(mass) and per cent change in VO₂(max) was significant (p<0.0001, r(2)=0.15), with a slope (95% CI) of 0.48 (0.30 to 0.67) intercept free to vary and 0.62 (0.46 to 0.77) when constrained through the origin. When separated, the correlations were significant for the altitude and control groups, with the correlation being stronger for the altitude group (slope of 0.57 to 0.72). With high statistical power, we conclude that altitude training of endurance athletes will result in an increase in VO₂(max) of more than half the magnitude of the increase in Hb(mass), which supports the use of altitude training by athletes. But race performance is not perfectly related to relative VO₂(max), and other non-haematological factors altered from altitude training, such as running economy and lactate threshold, may also be beneficial to performance.

[Difference in responses of major tree species growth to climate in the Miyaluo Mountains, western Sichuan, China].

PubMed

Guo, Ming-ming; Zhang, Yuan-dong; Wang, Xiao-chun; Liu, Shi-rong

2015-08-01

To explore the responses of different tree species growth to climate change in the semi-humid region of the eastern Tibetan Plateau, we investigated climate-growth relationships of Tsuga chinensis, Abies faxoniana, Picea purpurea at an altitude of 3000 m (low altitude) and A. faxoniana and Larix mastersiana at an altitude of 4000 m (high altitude) using tree ring-width chronologies (total of 182 cores) developed from Miyaluo, western Sichuan, China. Five residual chronologies were developed from the cross-dated ring width series using the program ARSTAN, and the relationships between monthly climate variables and tree-ring index were analyzed. Results showed that the chronologies of trees at low altitudes were negatively correlated with air temperature but positively with precipitation in April and May. This indicated that drought stress limited tree growth at low altitude, but different tree species showed significant variations. T. chinensis was most severely affected by drought stress, followed by A. faxoniana and P. purpurea. Trees at high altitude were mainly affected by growing season temperature. Tree-ring index of A. faxoniana was positively correlated with monthly minimum temperature in February and July of the current year and monthly maximum temperature in October of the previous year. Radial growth of L. mastersiana was positively correlated with monthly maximum temperature in May, and negatively with monthly mean temperature in February and monthly minimum temperature in March. In recent decadal years, the climate in northeast Tibetan Plateau had a warming and drying trend. If this trend continues, we could deduce that P. purpurea should grow faster than T. chinensis and A. faxoniana at low altitudes, while A. faxoniana would benefit more from global warming at high altitudes.

Rhodiola crenulata- and Cordyceps sinensis-based supplement boosts aerobic exercise performance after short-term high altitude training.

PubMed

Chen, Chung-Yu; Hou, Chien-Wen; Bernard, Jeffrey R; Chen, Chiu-Chou; Hung, Ta-Cheng; Cheng, Lu-Ling; Liao, Yi-Hung; Kuo, Chia-Hua

2014-09-01

High altitude training is a widely used strategy for improving aerobic exercise performance. Both Rhodiola crenulata (R) and Cordyceps sinensis (C) supplements have been reported to improve exercise performance. However, it is not clear whether the provision of R and C during high altitude training could further enhance aerobic endurance capacity. In this study, we examined the effect of R and C based supplementation on aerobic exercise capacity following 2-week high altitude training. Alterations to autonomic nervous system activity, circulatory hormonal, and hematological profiles were investigated. Eighteen male subjects were divided into two groups: Placebo (n=9) and R/C supplementation (RC, n=9). Both groups received either RC (R: 1400 mg+C: 600 mg per day) or the placebo during a 2-week training period at an altitude of 2200 m. After 2 weeks of altitude training, compared with Placebo group, the exhaustive run time was markedly longer (Placebo: +2.2% vs. RC: +5.7%; p<0.05) and the decline of parasympathetic (PNS) activity was significantly prevented in RC group (Placebo: -51% vs. RC: -41%; p<0.05). Red blood cell, hematocrit, and hemoglobin levels were elevated in both groups to a comparable extent after high altitude training (p<0.05), whereas the erythropoietin (EPO) level remained higher in the Placebo group (∼48% above RC values; p<0.05). The provision of an RC supplement during altitude training provides greater training benefits in improving aerobic performance. This beneficial effect of RC treatment may result from better maintenance of PNS activity and accelerated physiological adaptations during high altitude training.

The airglow layer emission altitude cannot be determined unambiguously from temperature comparison with lidars

NASA Astrophysics Data System (ADS)

Dunker, Tim

2018-05-01

I investigate the nightly mean emission height and width of the OH* (3-1) layer by comparing nightly mean temperatures measured by the ground-based spectrometer GRIPS 9 and the Na lidar at ALOMAR. The data set contains 42 coincident measurements taken between November 2010 and February 2014, when GRIPS 9 was in operation at the ALOMAR observatory (69.3° N, 16.0° E) in northern Norway. To closely resemble the mean temperature measured by GRIPS 9, I weight each nightly mean temperature profile measured by the lidar using Gaussian distributions with 40 different centre altitudes and 40 different full widths at half maximum. In principle, one can thus determine the altitude and width of an airglow layer by finding the minimum temperature difference between the two instruments. On most nights, several combinations of centre altitude and width yield a temperature difference of ±2 K. The generally assumed altitude of 87 km and width of 8 km is never an unambiguous, good solution for any of the measurements. Even for a fixed width of ˜ 8.4 km, one can sometimes find several centre altitudes that yield equally good temperature agreement. Weighted temperatures measured by lidar are not suitable to unambiguously determine the emission height and width of an airglow layer. However, when actual altitude and width data are lacking, a comparison with lidars can provide an estimate of how representative a measured rotational temperature is of an assumed altitude and width. I found the rotational temperature to represent the temperature at the commonly assumed altitude of 87.4 km and width of 8.4 km to within ±16 K, on average. This is not a measurement uncertainty.

Lower obesity rate during residence at high altitude among a military population with frequent migration: a quasi experimental model for investigating spatial causation.

PubMed

Voss, Jameson D; Allison, David B; Webber, Bryant J; Otto, Jean L; Clark, Leslie L

2014-01-01

We sought to evaluate whether residence at high altitude is associated with the development of obesity among those at increased risk of becoming obese. Obesity, a leading global health priority, is often refractory to care. A potentially novel intervention is hypoxia, which has demonstrated positive long-term metabolic effects in rats. Whether or not high altitude residence confers benefit in humans, however, remains unknown. Using a quasi-experimental, retrospective study design, we observed all outpatient medical encounters for overweight active component enlisted service members in the U.S. Army or Air Force from January 2006 to December 2012 who were stationed in the United States. We compared high altitude (>1.96 kilometers above sea level) duty assignment with low altitude (<0.98 kilometers). The outcome of interest was obesity related ICD-9 codes (278.00-01, V85.3x-V85.54) by Cox regression. We found service members had a lower hazard ratio (HR) of incident obesity diagnosis if stationed at high altitude as compared to low altitude (HR 0.59, 95% confidence interval [CI] 0.54-0.65; p<0.001). Using geographic distribution of obesity prevalence among civilians throughout the U.S. as a covariate (as measured by the Centers for Disease Control and Prevention and the REGARDS study) also predicted obesity onset among service members. In conclusion, high altitude residence predicts lower rates of new obesity diagnoses among overweight service members in the U.S. Army and Air Force. Future studies should assign exposure using randomization, clarify the mechanism(s) of this relationship, and assess the net balance of harms and benefits of high altitude on obesity prevention.

The effect of drought on photosynthetic plasticity in Marrubium vulgare plants growing at low and high altitudes.

PubMed

Habibi, Ghader; Ajory, Neda

2015-11-01

Photosynthesis is a biological process most affected by water deficit. Plants have various photosynthetic mechanisms that are matched to specific climatic zones. We studied the photosynthetic plasticity of C3 plants at water deficit using ecotypes of Marrubium vulgare L. from high (2,200 m) and low (1,100 m) elevation sites in the Mishou-Dagh Mountains of Iran. Under experimental drought, high-altitude plants showed more tolerance to water stress based on most of the parameters studied as compared to the low-altitude plants. Increased tolerance in high-altitude plants was achieved by lower levels of daytime stomatal conductance (g s) and reduced damaging effect on maximal quantum yield of photosystem II (PSII) (F v /F m ) coupled with higher levels of carotenoids and non-photochemical quenching (NPQ). High-altitude plants exhibited higher water use efficiency (WUE) than that in low-altitude plants depending on the presence of thick leaves and the reduced daytime stomatal conductance. Additionally, we have studied the oscillation in H(+) content and diel gas exchange patterns to determine the occurrence of C3 or weak CAM (Crassulacean acid metabolism) in M. vulgare through 15 days drought stress. Under water-stressed conditions, low-altitude plants exhibited stomatal conductance and acid fluctuations characteristic of C3 photosynthesis, though high-altitude plants exhibited more pronounced increases in nocturnal acidity and phosphoenolpyruvate carboxylase (PEPC) activity, suggesting photosynthetic flexibility. These results indicated that the regulation of carotenoids, NPQ, stomatal conductance and diel patterns of CO2 exchange presented the larger differences among studied plants at different altitudes and seem to be the protecting mechanisms controlling the photosynthetic performance of M. vulgare plants under drought conditions.

Natural and Diverted Low-Flow Duration Discharges for Streams Affected by the Waiahole Ditch System, Windward O`ahu, Hawai`i

USGS Publications Warehouse

Yeung, Chiu W.; Fontaine, Richard A.

2007-01-01

For nearly a century, the Waiahole Ditch System has diverted an average of approximately 27 million gallons per day of water from the wet, northeastern part of windward O`ahu, Hawai`i, to the dry, central part of the island to meet irrigation needs. The system intercepts large amounts of dike-impounded ground water at high altitudes (above approximately 700 to 800 ft) that previously discharged to Waiahole (and its tributaries Waianu and Uwao), Waikane, and Kahana Streams through seeps and springs. Diversion of this ground water has significantly diminished low flows in these streams. Estimates of natural and diverted flows are needed by water managers for (1) setting permanent instream flow standards to protect, enhance, and reestablish beneficial instream uses of water in the diverted streams and (2) allocating the diverted water for instream and offstream uses. Data collected before construction of the Waiahole Ditch System reflect natural (undiverted) flow conditions. Natural low-flow duration discharges for percentiles ranging from 50 to 99 percent were estimated for four sites at altitudes of 75 to 320 feet in Waiahole Stream (and its tributaries Waianu and Uwao Streams), for six sites at altitudes of 10 to 220 feet in Waikane Stream, and for three sites at altitudes of 30 to 80 feet in Kahana Stream. Among the available low-flow estimates along each affected stream, the highest natural Q50 (median) flows on Waiahole (altitude 250 ft), Waianu (altitude 75 ft), Waikane (altitude 75 ft), and Kahana Streams (altitude 30 ft) are 13, 7.0, 5.5, and 22 million gallons per day, respectively. Q50 (median) is just one of five duration percentiles presented in this report to quantify low-flow discharges. All flow-duration estimates were adjusted to a common period of 1960-2004 (called the base period). Natural flow-duration estimates compared favorably with limited pre-ditch streamflow data available for Waiahole and Kahana Streams. Data collected since construction of the ditch system reflect diverted flow conditions, which can be further divided into pre-release and post-release periods - several flow releases to Waiahole, Waianu, and Waikane Streams were initiated between December 1994 and October 2002. Comparison of pre-release to natural flows indicate that the effects of the Waiahole Ditch System diversion are consistently greater at lower low-flow conditions (Q99 to Q90) than at higher low-flow conditions (Q75 to Q50). Results also indicate that the effects of the diversion become less significant as the streams gain additional ground water at lower altitudes. For Waiahole Stream, pre-release flows range from 25 to 28 percent of natural flows at an altitude of 250 feet and from 19 to 20 percent at an altitude of 320 feet. For Waikane Stream, pre-release flows range from 30 to 46 percent of natural flows at an altitude of 10 feet and from 7 to 19 percent at an altitude of 220 feet. For Kahana Stream, pre-release flows range from 65 to 72 percent of natural flows at an altitude of 30 feet and from 58 to 71 percent at an altitude of 80 feet. Estimates of post-release flows were compared with estimates of natural flows to assess how closely current streamflows are to natural conditions. For Waianu Stream, post-release flows at an altitude of 75 feet are 41 to 46 percent lower than corresponding natural flows. For Waikane Stream, post-release flows at an altitude of 75 feet are within 12 percent of the corresponding natural flows. Comparisons of pre-release and post-release flows for Waikane Stream at altitudes of 10 to 220 feet were used to assess downstream changes in flow along the stream reach where flow releases were made. For a particular stream altitude, proportions of pre-release to post-release flows associated with median flows are consistently greater than proportions associated with lower low flows because the relative effect of the flow release is smaller at higher low flows. Similarly, for a particular f

Effect of acetazolamide on blood gases and 2,3 DPG during ascent and acclimatization to high altitude.

PubMed Central

Milles, J. J.; Chesner, I. M.; Oldfield, S.; Bradwell, A. R.

1987-01-01

Blood gases and red cell 2,3 DPG concentrations were measured during ascent and a stay for 6 days at 4846 m in 20 subjects. Acetazolamide improved Pa,O2 and reduced pH and Pa,CO2. 2,3 DPG concentrations were lower in the acetazolamide group during ascent and at high altitude. However, 2,3 DPG concentrations were significantly greater at high altitude in both the acetazolamide and placebo groups compared with low altitude. The acetazolamide group remained different from the placebo group during the stay at high altitude with higher Pa,O2, lower PaCO2, lower pH and lower 2,3 DPG concentrations. PMID:3118349

Altitude-related deaths in seven trekkers in the Himalayas.

PubMed Central

Dickinson, J; Heath, D; Gosney, J; Williams, D

1983-01-01

The clinical features and necropsy findings are described for seven trekkers in the Himalayas whose deaths were related to high altitude. The fatal outcome was due to serious pulmonary and cerebral disease. Oedema of the lungs and brain was prominent but so was thrombosis and haemorrhage, features of acute mountain sickness that have received insufficient recognition in the past. Most of the men were middle aged. Some began their trekking soon after flying to high altitude before becoming acclimatised and some remained at high altitude or climbed even higher despite the development of vomiting, breathlessness, and exhaustion. In one case death occurred despite prompt recognition and treatment of symptoms by administration of oxygen and swift evacuation to low altitude. Images PMID:6623417

Free-Flight Test of a Technique for Inflating an NASA 12-Foot-Diameter Sphere at High Altitudes

NASA Technical Reports Server (NTRS)

Kehlet, Alan B.; Patterson, Herbert G.

1959-01-01

A free-flight test has been conducted to check a technique for inflating an NASA 12-foot-diameter inflatable sphere at high altitudes. Flight records indicated that the nose section was successfully separated from the booster rocket, that the sphere was ejected, and that the nose section was jettisoned from the fully inflated sphere. On the basis of preflight and flight records, it is believed that the sphere was fully inflated by the time of peak altitude (239,000 feet). Calculations showed that during descent, jettison of the nose section occurred above an altitude of 150,000 feet. The inflatable sphere was estimated to start to deform during descent at an altitude of about 120,000 feet.

Overview of Radiation Environments and Human Exposures

NASA Technical Reports Server (NTRS)

Wilson, John W.

2004-01-01

Human exposures to ionizing radiation have been vastly altered by developing technology in the last century. This has been most obvious in the development of radiation generating devices and the utilization of nuclear energy. But even air travel has had its impact on human exposure. Human exposure increases with advancing aircraft technology as a result of the higher operating altitudes reducing the protective cover provided by the Earth s atmosphere from extraterrestrial radiations. This increase in operating altitudes is taken to a limit by human operations in space. Less obvious is the changing character of the radiations at higher altitudes. The associated health risks are less understood with increasing altitude due to the increasing complexity and new field components found in high altitude and space operations.

Pulmonary vascular disease in a rabbit a high altitude

NASA Astrophysics Data System (ADS)

Heath, Donald; Williams, David; Rios-Datenz, Jaime; Gosney, John

1990-03-01

A male weanling rabbit of the New Zealand White strain, born and living at an altitude of 3800 m in La Paz, Bolivia, developed right ventricular hypertrophy. This was found to be associated with growth of vascular smooth muscle cells in the intima of pulmonary arterioles, and contrasted with muscularization of the walls of pulmonary arterioles, without extension into the intima, found in a healthy, high-altitude control rabbit of the same strain. A low-altitude control showed no such muscularization. It is concluded that alveolar hypoxia, acting directly or through an intermediate agent, is a growth factor for vascular smooth muscle cells in pulmonary arterioles. This is the first report of pulmonary vascular disease due to high altitude in rabbits.

Further considerations of engine emissions from subsonic aircraft at cruise altitude

NASA Astrophysics Data System (ADS)

Lee, S. H.; Le Dilosquer, M.; Singh, R.; Rycroft, M. J.

The most significant man-made sources of pollution of the higher troposphere and lower stratosphere are exhaust emissions from civil subsonic aircraft at cruise altitude (8-12 km). This paper examines such issues by computational modelling of Boeing 747-400 flights during their cruise phase between selected city pairs, for example London to Tokyo. The engine performance, exhaust pollutant prediction, and detailed flight history analysis effects of different Mach numbers and of increasing the cruise altitude from 9.8 to 12.1 km during the flight rather than staying at a constant cruise altitude of 10.5 km are studied in detail. To minimise the overall effects of atmospheric pollution, a Mach number of 0.85 and increasing altitude is the favoured cruise technique.

14 CFR 135.293 - Initial and recurrent pilot testing requirements.

Code of Federal Regulations, 2011 CFR

2011-01-01

..., high altitude weather; (7) Procedures for— (i) Recognizing and avoiding severe weather situations; (ii) Escaping from severe weather situations, in case of inadvertent encounters, including low-altitude windshear (except that rotorcraft pilots are not required to be tested on escaping from low-altitude...

14 CFR 135.293 - Initial and recurrent pilot testing requirements.

Code of Federal Regulations, 2010 CFR

2010-01-01

..., high altitude weather; (7) Procedures for— (i) Recognizing and avoiding severe weather situations; (ii) Escaping from severe weather situations, in case of inadvertent encounters, including low-altitude windshear (except that rotorcraft pilots are not required to be tested on escaping from low-altitude...

Acute Exposure of College Basketball Players to Moderate Altitude: Selected Physiological Responses.

ERIC Educational Resources Information Center

Noble, Bruce J.; Maresh, Carl M.

1979-01-01

In general, basketball players with moderately high aerobic power who reside at an altitude of 1,000 m do not display the hypoxic response to an altitude of 2,200 m expected of sea level residents and aerobically trained athletes. (JD)

Data catalog series for space science and applications flight missions. Volume 2A: Descriptions of geostationary and high-altitude scientific spacecraft and investigations

NASA Technical Reports Server (NTRS)

Hills, H. K. (Editor); Littlefield, R. G. (Editor); Schofield, N. J. (Editor); Vetts, J. I. (Editor)

1982-01-01

Data from Earth-orbiting spacecraft at geostationary and higher altitudes was cataloged. Three lunar-orbiting spacecraft and some others whose apogees did not attain the geostationary altitude are included.

14 CFR 121.358 - Low-altitude windshear system equipment requirements.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Low-altitude windshear system equipment... OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Instrument and Equipment Requirements § 121.358 Low-altitude windshear system equipment requirements. (a) Airplanes manufactured after January...

14 CFR 121.358 - Low-altitude windshear system equipment requirements.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Low-altitude windshear system equipment... OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Instrument and Equipment Requirements § 121.358 Low-altitude windshear system equipment requirements. (a) Airplanes manufactured after January...

14 CFR 121.358 - Low-altitude windshear system equipment requirements.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Low-altitude windshear system equipment... OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Instrument and Equipment Requirements § 121.358 Low-altitude windshear system equipment requirements. (a) Airplanes manufactured after January...

14 CFR 121.358 - Low-altitude windshear system equipment requirements.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Low-altitude windshear system equipment... OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Instrument and Equipment Requirements § 121.358 Low-altitude windshear system equipment requirements. (a) Airplanes manufactured after January...

14 CFR 121.358 - Low-altitude windshear system equipment requirements.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Low-altitude windshear system equipment... OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Instrument and Equipment Requirements § 121.358 Low-altitude windshear system equipment requirements. (a) Airplanes manufactured after January...

14 CFR 135.203 - VFR: Minimum altitudes.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false VFR: Minimum altitudes. 135.203 Section 135.203 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED... Operating Limitations and Weather Requirements § 135.203 VFR: Minimum altitudes. Except when necessary for...

14 CFR 135.203 - VFR: Minimum altitudes.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false VFR: Minimum altitudes. 135.203 Section 135.203 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED... Operating Limitations and Weather Requirements § 135.203 VFR: Minimum altitudes. Except when necessary for...

14 CFR 135.203 - VFR: Minimum altitudes.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false VFR: Minimum altitudes. 135.203 Section 135.203 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED... Operating Limitations and Weather Requirements § 135.203 VFR: Minimum altitudes. Except when necessary for...

Atmospheric Turbulence Measurements Obtained from Airplane Operations at Altitudes Between 20,000 and 75,000 Feet for Several Areas in the Northern Hemisphere

NASA Technical Reports Server (NTRS)

Coleman, Thomas L.; Steiner, Roy

1960-01-01

Measurements of clear-air turbulence by use of airplane-borne instrumentation have been obtained from NASA VGH recorders during research flights of Lockheed U-2 airplanes to altitudes of 75,000 feet over several areas of the Northern Hemisphere. An analysis of these data has indicated that for the higher altitudes (50,000 to 75,000 feet), turbulence is both less frequent and less severe than for the lower altitudes (20,000 to 50,000 feet). Turbulence appears to be present at the high altitudes (60,000 to 75,000 feet) less than 1 percent of the time. Moderately heavy turbulence appears to exist on occasion at altitudes of about 50,000 feet over Japan. As a consequence, the gust experience appears to be more severe for operations over Japan than for the other areas. Less than 50 percent of the turbulent areas exceeded 10 miles in length.

Can High Altitude Influence Cytokines and Sleep?

PubMed Central

de Aquino Lemos, Valdir; dos Santos, Ronaldo Vagner Thomatieli; Lira, Fabio Santos; Rodrigues, Bruno; Tufik, Sergio; de Mello, Marco Tulio

2013-01-01

The number of persons who relocate to regions of high altitude for work, pleasure, sport, or residence increases every year. It is known that the reduced supply of oxygen (O2) induced by acute or chronic increases in altitude stimulates the body to adapt to new metabolic challenges imposed by hypoxia. Sleep can suffer partial fragmentation because of the exposure to high altitudes, and these changes have been described as one of the responsible factors for the many consequences at high altitudes. We conducted a review of the literature during the period from 1987 to 2012. This work explored the relationships among inflammation, hypoxia and sleep in the period of adaptation and examined a novel mechanism that might explain the harmful effects of altitude on sleep, involving increased Interleukin-1 beta (IL-1β), Interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) production from several tissues and cells, such as leukocytes and cells from skeletal muscle and brain. PMID:23690660

Variability of reflectance measurements with sensor altitude and canopy type

NASA Technical Reports Server (NTRS)

Daughtry, C. S. T.; Vanderbilt, V. C.; Pollara, V. J.

1981-01-01

Data were acquired on canopies of mature corn planted in 76 cm rows, mature soybeans planted in 96 cm rows with 71 percent soil cover, and mature soybeans planed in 76 cm rows with 100 percent soil cover. A LANDSAT band radiometer with a 15 degree field of view was used at ten altitudes ranging from 0.2 m to 10 m above the canopy. At each altitude, measurements were taken at 15 cm intervals also a 2.0 m transect perpendicular to the crop row direction. Reflectance data were plotted as a function of altitude and horizontal position to verify that the variance of measurements at low altitudes was attributable to row effects which disappear at higher altitudes where the sensor integrate across several rows. The coefficient of variation of reflectance decreased exponentially as the sensor was elevated. Systematic sampling (at odd multiples of 0.5 times the row spacing interval) required fewer measurements than simple random sampling over row crop canopies.

Pathfinder aircraft liftoff on altitude record setting flight of 71,500 feet

NASA Image and Video Library

1997-07-07

The Pathfinder aircraft has set a new unofficial world record for high-altitude flight of over 71,500 feet for solar-powered aircraft at the U.S. Navy's Pacific Missile Range Facility, Kauai, Hawaii. Pathfinder was designed and manufactured by AeroVironment, Inc, of Simi Valley, California, and was operated by the firm under a jointly sponsored research agreement with NASA's Dryden Flight Research Center, Edwards, California. Pathfinder's record-breaking flight occurred July 7, 1997. The aircraft took off at 11:34 a.m. PDT, passed its previous record altitude of 67,350 feet at about 5:45 p.m. and then reached its new record altitude at 7 p.m. The mission ended with a perfect nighttime landing at 2:05 a.m. PDT July 8. The new record is the highest altitude ever attained by a propellor-driven aircraft. Before Pathfinder, the altitude record for propellor-driven aircraft was 67,028 feet, set by the experimental Boeing Condor remotely piloted aircraft.

Geopotential Field Anomaly Continuation with Multi-Altitude Observations

NASA Technical Reports Server (NTRS)

Kim, Jeong Woo; Kim, Hyung Rae; von Frese, Ralph; Taylor, Patrick; Rangelova, Elena

2012-01-01

Conventional gravity and magnetic anomaly continuation invokes the standard Poisson boundary condition of a zero anomaly at an infinite vertical distance from the observation surface. This simple continuation is limited, however, where multiple altitude slices of the anomaly field have been observed. Increasingly, areas are becoming available constrained by multiple boundary conditions from surface, airborne, and satellite surveys. This paper describes the implementation of continuation with multi-altitude boundary conditions in Cartesian and spherical coordinates and investigates the advantages and limitations of these applications. Continuations by EPS (Equivalent Point Source) inversion and the FT (Fourier Transform), as well as by SCHA (Spherical Cap Harmonic Analysis) are considered. These methods were selected because they are especially well suited for analyzing multi-altitude data over finite patches of the earth such as covered by the ADMAP database. In general, continuations constrained by multi-altitude data surfaces are invariably superior to those constrained by a single altitude data surface due to anomaly measurement errors and the non-uniqueness of continuation.

Geopotential Field Anomaly Continuation with Multi-Altitude Observations

NASA Technical Reports Server (NTRS)

Kim, Jeong Woo; Kim, Hyung Rae; vonFrese, Ralph; Taylor, Patrick; Rangelova, Elena

2011-01-01

Conventional gravity and magnetic anomaly continuation invokes the standard Poisson boundary condition of a zero anomaly at an infinite vertical distance from the observation surface. This simple continuation is limited, however, where multiple altitude slices of the anomaly field have been observed. Increasingly, areas are becoming available constrained by multiple boundary conditions from surface, airborne, and satellite surveys. This paper describes the implementation of continuation with multi-altitude boundary conditions in Cartesian and spherical coordinates and investigates the advantages and limitations of these applications. Continuations by EPS (Equivalent Point Source) inversion and the FT (Fourier Transform), as well as by SCHA (Spherical Cap Harmonic Analysis) are considered. These methods were selected because they are especially well suited for analyzing multi-altitude data over finite patches of the earth such as covered by the ADMAP database. In general, continuations constrained by multi-altitude data surfaces are invariably superior to those constrained by a single altitude data surface due to anomaly measurement errors and the non-uniqueness of continuation.

Wind study for high altitude platform design

NASA Technical Reports Server (NTRS)

Strganac, T. W.

1979-01-01

An analysis of upper air winds was performed to define the wind environment at potential operating altitudes for high-altitude powered platform concepts. Expected wind conditions of the contiguous United States, Pacific area (Alaska to Sea of Japan), and European area (Norwegian and Mediterranean Seas) were obtained using a representative network of sites selected based upon adequate high-altitude sampling, geographic dispersion, and observed upper wind patterns. A data base of twenty plus years of rawinsonde gathered wind information was used in the analysis. Annual variations from surface to 10 mb (approximately 31 km) pressure altitude were investigated to encompass the practical operating range for the platform concepts. Parametric analysis for the United States and foreign areas was performed to provide a basis for vehicle system design tradeoffs. This analysis of wind magnitudes indicates the feasibility of annual operation at a majority of sites and more selective seasonal operation for the extreme conditions between the pressure altitudes of 100 to 25 mb based upon the assumed design speeds.

Ice Crystal Icing Engine Testing in the NASA Glenn Research Center's Propulsion Systems Laboratory: Altitude Investigation

NASA Technical Reports Server (NTRS)

Oliver, Michael J.

2014-01-01

The National Aeronautics and Space Administration (NASA) conducted a full scale ice crystal icing turbofan engine test using an obsolete Allied Signal ALF502-R5 engine in the Propulsion Systems Laboratory (PSL) at NASA Glenn Research Center. The test article used was the exact engine that experienced a loss of power event after the ingestion of ice crystals while operating at high altitude during a 1997 Honeywell flight test campaign investigating the turbofan engine ice crystal icing phenomena. The test plan included test points conducted at the known flight test campaign field event pressure altitude and at various pressure altitudes ranging from low to high throughout the engine operating envelope. The test article experienced a loss of power event at each of the altitudes tested. For each pressure altitude test point conducted the ambient static temperature was predicted using a NASA engine icing risk computer model for the given ambient static pressure while maintaining the engine speed.

Investigation of thermospheric winds relative to space station orbital altitudes

NASA Technical Reports Server (NTRS)

Susko, M.

1984-01-01

An investigation of thermospheric winds, relative to the space station orbital altitudes, was made in order to provide information that is useful in an environmental disturbance assessment. Current plans are for this low Earth orbiting facility to orbit at an inclination of 28.5 deg. The orbital altitudes were not yet defined due to the evolutionary configuration of the Space Station. The upper and lower bounds of the orbital altitudes will be based on constraints set by the drag and expected orbital decay and delivery altitude capability of the Shuttle. The orbital altitude will be estimated on the order of 500 km. Neutral winds in the region from about 80 to 600 km which were derived from satellite drag data, Fabry-Perot interferometers, sounding rockets, ground-based optical Doppler techniques, incoherent scatter radar measurements from Millstone Hill combined with the mass spectrometer and lithium trail neutral wind measurements are examined. The equations of motion of the low Earth orbiting facility are also discussed.

Wind study for high altitude platform design

NASA Technical Reports Server (NTRS)

Strganac, T. W.

1979-01-01

An analysis of upper air winds was performed to define the wind environment at potential operating altitudes for high altitude powered platform concepts. Wind conditions of the continental United States, Pacific area (Alaska to Sea of Japan), and European area (Norwegian and Mediterranean Sea) were obtained using a representative network of sites selected based upon adequate high altitude sampling, geographic dispersion, and observed upper wind patterns. A data base of twenty plus years of rawinsonde gathered wind information was used in the analysis. Annual variations from surface to 10 mb pressure altitude were investigated to encompass the practical operating range for the platform concepts. Parametric analysis for the United States and foreign areas was performed to provide a basis for vehicle system design tradeoffs. This analysis of wind magnitudes indicates the feasibility of annual operation at a majority of sites and more selective seasonal operation for the extreme conditions between the pressure altitudes of 100 to 25 mb based upon the assumed design speeds.

Pre-existing cardiovascular conditions and high altitude travel. Consensus statement of the Medical Commission of the Union Internationale des Associations d'Alpinisme (UIAA MedCom) Travel Medicine and Infectious Disease.

PubMed

Donegani, Enrico; Hillebrandt, David; Windsor, Jeremy; Gieseler, Ulf; Rodway, George; Schöffl, Volker; Küpper, Thomas

2014-01-01

The number of persons visiting high altitude regions for various purposes (recreation, business etc.), and the age of people who do so, increases. Therefore there are more and more patients who need specific and individual advice to prevent emergency situations at altitude and to deal with emergencies if the safety strategy should fail. Since literature concerning cardiocirculatory diseases at altitude is scarce and studies with a controlled setting and high evidence level are missing, UIAA MedCom has checked all available literature for specific information to enable physicians who are active in travel or high altitude medicine to advise the patients at the highest possible level of evidence. It must be pointed out that there are several other medical fields where such information is mandatory, e.g. in occupational medicine, when employees depart to high altitude destinations for business purposes. The recommendations are based on a detailed literature research (databases, handbooks and the respective references). For easier use the paper has been structured as follows: general information, cardiocirculatory system and ECG at altitude, several cardiocirculatory diseases and their specific recommendations. The commission concludes, that a general "don't go!" is no state-of-the-art advice for the patients. With the information presented here a safe trip to altitude should be possible for many patients. Copyright © 2014 Elsevier Ltd. All rights reserved.

Soil carbon and nitrogen stocks in forests along an altitudinal gradient in the eastern Himalayas and a meta-analysis of global data.

PubMed

Tashi, Sonam; Singh, Balwant; Keitel, Claudia; Adams, Mark

2016-06-01

High-altitude soils potentially store a large pool of carbon (C) and nitrogen (N). The assessment of total C and N stocks in soils is vital to understanding the C and N dynamics in terrestrial ecosystems. In this study, we examined effects of altitude and forest composition on soil C and N along a transect from 317 to 3300 m a.s.l. in the eastern Himalayas. We used meta-analysis to establish the context for our results on the effects of altitude on soil C, including variation with depth. Total C and N contents of soils significantly increased with altitude, but decreased with soil depth. Carbon and N were similarly correlated with altitude and temperature, and temperature was seemingly the main driver of soil C along the altitudinal gradient. Altitude accounted for 73% of the variation in C and 47% of the variation in N stocks. Soil pH and cation exchange capacity were correlated with both soil C and N stocks. Increases in soil C and N stocks were related to forest composition, forest basal area as well as quantity of leaf litter that were in turn influenced by altitude and temperature. Concentrations of C in foliage increased by 2.1% for every 1000 m rise in altitude, while that in leaf litter increased by 2.3%. © 2016 John Wiley & Sons Ltd.

Effect of different simulated altitudes on repeat-sprint performance in team-sport athletes.

PubMed

Goods P, S R; Dawson, Brian T; Landers, Grant J; Gore, Christopher J; Peeling, Peter

2014-09-01

This study aimed to assess the impact of 3 heights of simulated altitude exposure on repeat-sprint performance in team-sport athletes. Ten trained male team-sport athletes completed 3 sets of repeated sprints (9 × 4 s) on a nonmotorized treadmill at sea level and at simulated altitudes of 2000, 3000, and 4000 m. Participants completed 4 trials in a random order over 4 wk, with mean power output (MPO), peak power output (PPO), blood lactate concentration (Bla), and oxygen saturation (SaO2) recorded after each set. Each increase in simulated altitude corresponded with a significant decrease in SaO2. Total work across all sets was highest at sea level and correspondingly lower at each successive altitude (P < .05; sea level < 2000 m < 3000 m < 4000 m). In the first set, MPO was reduced only at 4000 m, but for subsequent sets, decreases in MPO were observed at all altitudes (P < .05; 2000 m < 3000 m < 4000 m). PPO was maintained in all sets except for set 3 at 4000 m (P < .05; vs sea level and 2000 m). BLa levels were highest at 4000 m and significantly greater (P < .05) than at sea level after all sets. These results suggest that "higher may not be better," as a simulated altitude of 4000 m may potentially blunt absolute training quality. Therefore, it is recommended that a moderate simulated altitude (2000-3000 m) be employed when implementing intermittent hypoxic repeat-sprint training for team-sport athletes.

The influence of microclimates and fog on stable isotope signatures used in interpretation of regional hydrology: East Maui, Hawaii

USGS Publications Warehouse

Scholl, M.A.; Gingerich, S.B.; Tribble, G.W.

2002-01-01

Stable isotopes of precipitation, ground water and surface water measured on the windward side of East Maui from 0 to 3055 m altitude were used to determine recharge sources for stream flow and ground water. Correct interpretation of the hydrology using rainfall ??18O gradients with altitude required consideration of the influence of fog, as fog samples had isotopic signatures enriched by as much as 3??? in ??18O and 21??? in ??D compared to volume-weighted average precipitation at the same altitude. The isotopic analyses suggested that fog drip was a major component of stream flow and shallow ground water at higher altitudes in the watershed. 18O/altitude gradients in rainfall were comparable for similar microclimates on Maui (this study) and Hawaii Island (1990-1995 study), however, East Maui ??18O values for rain in trade-wind and high-altitude microclimates were enriched compared to those from Hawaii Island. Isotopes were used to interpret regional hydrology in this volcanic island aquifer system. In part of the study area, stable isotopes indicate discharge of ground water recharged at least 1000 m above the sample site. This deep-flowpath ground water was found in springs from sea level up to 240 m altitude, indicating saturation to altitudes much higher than a typical freshwater lens. These findings help in predicting the effects of ground water development on stream flow in the area. Published by Elsevier Science B.V.

Python Turboprop Prepared for a Test in the Altitude Wind Tunnel

NASA Image and Video Library

1949-08-21

A 3670-horsepower Armstrong-Siddeley Python turboprop being prepared for tests in the Altitude Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. In 1947 Lewis researcher Walter Olsen led a group of representatives from the military, industry, and the NACA on a fact finding mission to investigate the technological progress of British turbojet manufacturers. Afterwards several British engines, including the Python, were brought to Cleveland for testing in Lewis’s altitude facilities. The Python was a 14-stage axial-flow compressor turboprop with a fixed-area nozzle and contra-rotating propellers. Early turboprops combined the turbojet and piston engine technologies. They could move large quantities of air so required less engine speed and thus less fuel. This was very appealing to the military for some applications. The military asked the NACA to compare the Python’s performance at sea to that at high altitudes. The NACA researchers studied the Python in the Altitude Wind Tunnel from July 1949 through January 1950. It was the first time the tunnel was used to study an engine with the sole purpose of learning about, not improving it. They analyzed the engine’s dynamic response using a frequency response method at altitudes between 10,000 to 30,000 feet. Lewis researchers found that they could predict the dynamic response characteristics at any altitude from the data obtained from any other specific altitude. This portion of the testing was completed during a single test run.

40 CFR 86.1604 - Conditions for disapproval.

Code of Federal Regulations, 2011 CFR

2011-07-01

... adjustment control in use and provides appropriate instruction as part of the high-altitude performance... Altitude Performance Adjustments for New and In-Use Motor Vehicles and Engines § 86.1604 Conditions for disapproval. (a) The Administrator shall not approve altitude performance adjustments that will: (1) Cause any...

40 CFR 86.095-30 - Certification.

Code of Federal Regulations, 2010 CFR

2010-07-01

... a designated low-altitude location if the manufacturer has informed its dealers and field representatives about the terms of the high-altitude regulations, has not caused the improper sale itself, and has... light-duty truck which has been exempted from compliance with emission standards at low altitude, as...

40 CFR 86.095-30 - Certification.

Code of Federal Regulations, 2011 CFR

2011-07-01

... a designated low-altitude location if the manufacturer has informed its dealers and field representatives about the terms of the high-altitude regulations, has not caused the improper sale itself, and has... light-duty truck which has been exempted from compliance with emission standards at low altitude, as...

14 CFR 91.515 - Flight altitude rules.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false Flight altitude rules. 91.515 Section 91...) AIR TRAFFIC AND GENERAL OPERATING RULES GENERAL OPERATING AND FLIGHT RULES Large and Turbine-Powered Multiengine Airplanes and Fractional Ownership Program Aircraft § 91.515 Flight altitude rules. (a...

14 CFR 27.87 - Height-speed envelope.

Code of Federal Regulations, 2012 CFR

2012-01-01

... selected by the applicant for each altitude covered by paragraph (a)(1) of this section. For helicopters...— (1) For single-engine helicopters, full autorotation; (2) For multiengine helicopters, OEI (where... altitude or the maximum altitude capability of the helicopter, whichever is less, and (3) For other...

14 CFR 27.87 - Height-speed envelope.

Code of Federal Regulations, 2014 CFR

2014-01-01

... selected by the applicant for each altitude covered by paragraph (a)(1) of this section. For helicopters...— (1) For single-engine helicopters, full autorotation; (2) For multiengine helicopters, OEI (where... altitude or the maximum altitude capability of the helicopter, whichever is less, and (3) For other...

14 CFR 27.87 - Height-speed envelope.

Code of Federal Regulations, 2013 CFR

2013-01-01

... selected by the applicant for each altitude covered by paragraph (a)(1) of this section. For helicopters...— (1) For single-engine helicopters, full autorotation; (2) For multiengine helicopters, OEI (where... altitude or the maximum altitude capability of the helicopter, whichever is less, and (3) For other...

Human Cerebral Function at High Altitude.

DTIC Science & Technology

1985-03-01

increasing altitude. At the highest altitudes the % mountaineers’ behavior may be similar to an individual with a known acute organic brain syndrome (10...expedition. Only the male climbers ascended over 5,500 m. Of these, half experienced symptoms similar to an acute organic brain syndrome ; "for

The FAA altitude chamber training flight profile : a survey of altitude reactions, 1965-1989.

DOT National Transportation Integrated Search

1990-09-01

Reactions from 1,161 trainees out of 12,759 trainees subjected to the FAA altitude chamber training flights from 1965-1989 are annotated in this survey. Although there were some mild and expected reactions, these training profiles appear to provide a...

77 FR 7005 - Airworthiness Directives; Eurocopter Deutschland GMBH Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-10

... delivered fuel flow than the engine fuel flow demand needed to achieve the OEI rating at high altitude. They...-engine-inoperative (OEI) rating at altitudes above 10,000 feet. This condition could result in high... AD would require installing a placard that corresponds to the maximum permissible flight altitude...

76 FR 2801 - Revocation and Establishment of Compulsory Reporting Points; Alaska

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-18

... removes and establishes high altitude Alaskan compulsory reporting points in the vicinity of the United... establishing the TOVAD Compulsory Reporting Point on the U.S./Canadian border. Alaskan High Altitude Reporting... airspace. This regulation is within the scope of that authority as it amends High Altitude Compulsory...

14 CFR 29.1045 - Climb cooling test procedures.

Code of Federal Regulations, 2010 CFR

2010-01-01

... continuous power (or at full throttle when above the critical altitude); (2) For helicopters for which the... the critical altitude); and (3) For other rotorcraft, be at maximum continuous power (or at full throttle when above the critical altitude). (d) After temperatures have stabilized in flight, the climb...

14 CFR 29.1045 - Climb cooling test procedures.

Code of Federal Regulations, 2011 CFR

2011-01-01

... continuous power (or at full throttle when above the critical altitude); (2) For helicopters for which the... the critical altitude); and (3) For other rotorcraft, be at maximum continuous power (or at full throttle when above the critical altitude). (d) After temperatures have stabilized in flight, the climb...

77 FR 32884 - Airworthiness Directives; Eurocopter Deutschland GMBH Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-04

... than the engine fuel flow demand needed to achieve the OEI rating at high altitude. They state that... above 10,000 feet. This condition could result in high altitude operations when full OEI engine power is... installing a placard that corresponds to the maximum permissible flight altitude, amending the Rotorcraft...

Users guide to high altitude imagery of Michigan

NASA Technical Reports Server (NTRS)

1973-01-01

A guide to the high altitude imagery of Michigan outlines the areas of the state covered by selected recent high altitude aircraft and Earth Resources Technology Satellite flights. The types of remote sensing used are described. Maps of the flight coverage areas are included along with price lists of available imagery.

14 CFR 23.841 - Pressurized cabins.

Code of Federal Regulations, 2013 CFR

2013-01-01

... emergency procedure. A 17-second flight crew recognition and reaction time must be applied between cabin... pressurization system must prevent the cabin altitude from exceeding the cabin altitude-time history shown in... exceeds 25,000 feet, the maximum time the cabin altitude may exceed 25,000 feet is 2 minutes; time...

14 CFR 23.841 - Pressurized cabins.

Code of Federal Regulations, 2014 CFR

2014-01-01

... emergency procedure. A 17-second flight crew recognition and reaction time must be applied between cabin... pressurization system must prevent the cabin altitude from exceeding the cabin altitude-time history shown in... exceeds 25,000 feet, the maximum time the cabin altitude may exceed 25,000 feet is 2 minutes; time...

Safely Enabling Civilian Unmanned Aerial System (UAS) Operations in Low-Altitude Airspace by Unmanned Aerial System Traffic Management (UTM)

NASA Technical Reports Server (NTRS)

Kopardekar, Parimal Hemchandra

2015-01-01

Many UAS will operate at lower altitude (Class G, below 2000 feet). There is an urgent need for a system for civilian low-altitude airspace and UAS operations. Stakeholders want to work with NASA to enable safe operations.

Safely Enabling Civilian Unmanned Aerial System (UAS) Operations In Low-Altitude Airspace By Unmanned Aerial System Traffic Management (UTM)

NASA Technical Reports Server (NTRS)

Kopardekar, Parimal H.

2015-01-01

Many UAS will operate at lower altitude (Class G, below 2000 feet)There is urgent need for a system for civilian low-altitude airspace and UAS operations. Stakeholders want to work with NASA to enable safe operations.

10 CFR 862.6 - Voluntary minimum altitude.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Voluntary minimum altitude. 862.6 Section 862.6 Energy DEPARTMENT OF ENERGY RESTRICTIONS ON AIRCRAFT LANDING AND AIR DELIVERY AT DEPARTMENT OF ENERGY NUCLEAR SITES § 862.6 Voluntary minimum altitude. In addition to complying with all applicable FAA prohibitions or...

Altitude Preexposure Recommendations for Inducing Acclimatization

DTIC Science & Technology

2010-01-01

1997). Exercise responses after altitude acclimatization are retained during reintroduction to altitude. Med. Sci. Sports Exerc. 29:1588–1595. Bisgard...Fregly and C.M. Blatteis, eds. Oxford University Press, New York; pp. 1207– 1239. Brooks G.A., Butterfield G.E., Wolfe R.R., Groves B.M., Mazzeo R.S

14 CFR 25.1527 - Ambient air temperature and operating altitude.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Ambient air temperature and operating... Information Operating Limitations § 25.1527 Ambient air temperature and operating altitude. The extremes of the ambient air temperature and operating altitude for which operation is allowed, as limited by...

14 CFR 25.1527 - Ambient air temperature and operating altitude.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Ambient air temperature and operating... Information Operating Limitations § 25.1527 Ambient air temperature and operating altitude. The extremes of the ambient air temperature and operating altitude for which operation is allowed, as limited by...

14 CFR 25.1527 - Ambient air temperature and operating altitude.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Ambient air temperature and operating... Information Operating Limitations § 25.1527 Ambient air temperature and operating altitude. The extremes of the ambient air temperature and operating altitude for which operation is allowed, as limited by...

14 CFR 25.1527 - Ambient air temperature and operating altitude.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Ambient air temperature and operating... Information Operating Limitations § 25.1527 Ambient air temperature and operating altitude. The extremes of the ambient air temperature and operating altitude for which operation is allowed, as limited by...

Development of Air Force aerial spray night operations: High altitude swath characterization

USDA-ARS?s Scientific Manuscript database

Multiple trials were conducted from 2006 to 2014 in an attempt to validate aerial spray efficacy at altitudes conducive to night spray operations using night vision goggles (NVG). Higher altitude application of pesticide (>400 feet above ground level [AGL]) suggested that effective vector control mi...

Application of frequency domain handling qualities criteria to the longitudinal landing task

NASA Technical Reports Server (NTRS)

Sarrafian, S. K.; Powers, B. G.

1985-01-01

Three frequency-domain handling qualities criteria have been applied to the observed data to correlate the actual pilot ratings assigned to generic transport configurations with stability augmentation during the longitudinal landing task. The criteria are based on closed-loop techniques using pitch attitude, altitude rate at the pilot station, and altitude at the pilot station as dominating control parameters during this task. It is found that most promising results are obtained with altitude control performed by closing an inner loop on pitch attitude and closing an outer loop on altitude.

The impact of altitude on hospitalization and hospital mortality from pandemic 2009 influenza A (H1N1) virus pneumonia in Mexico.

PubMed

Pérez-Padilla, Rogelio; García-Sancho, Cecilia; Fernández, Rosario; Franco-Marina, Francisco; López-Gatell, Hugo; Bojórquez, Ietza

2013-01-01

To determine the effect of altitude of residence on influenza A (H1N1). We analyzed 207 135 officially notified of influenza-like illness (ILI) cases, 23 048 hospitalizations and 573 deaths during the first months of the novel pandemic influenza A H1N1 virus, to examine if residents of high altitude had more frequently these adverse outcomes. Adjusted rates for hospitalization and hospital mortality rates increased with altitude, probably due to hypoxemia.

Altitude profiles of temperature from 4 to 80 km over the tropics from MST radar and lidar

NASA Astrophysics Data System (ADS)

Parameswaran, K.; Sasi, M. N.; Ramkumar, G.; Nair, P. R.; Deepa, V.; Murthy, B. V. K.; Nayar, S. R. P.; Revathy, K.; Mrudula, G.; Satheesan, K.; Bhavanikumar, Y.; Sivakumar, V.; Raghunath, K.; Rajendraprasad, T.; Krishnaiah, M.

2000-10-01

Using ground-based techniques of MST radar and Lidar, temperature profiles in the entire height range of 4 to 75km are obtained for the first time at a tropical location. The temporal resolution of the profiles is ~1h in the lower altitudes and 12.5min in the higher altitudes and altitude resolution is ~300m. The errors involved in the derived values are presented. Preliminary analysis of temperature variations in a night revealed fluctuations with characteristics resembling those of large-scale gravity waves.

Altitude Investigation of Performance of Turbine-propeller Engine and Its Components

NASA Technical Reports Server (NTRS)

Wallner, Lewis E; Saari, Martin J

1950-01-01

An investigation was conducted on a turbine-propeller engine in the NACA Lewis altitude wind tunnel at altitudes from 5000 to 35,000 feet. The applicability of generalized parameters to turbine-propeller engine data, analyses of the compressor, the combustion chambers, and the turbine, and a study of the over-all engine performance are reported. Engine performance data obtained at sea-level static conditions could be used to predict static performance at altitudes up to 35,000 feet by use of the standard generalized parameters.

Approximate altitude of water levels in wells completed in the Chicot and Evangeline aquifers in the Houston area, Texas, January-February 1991

USGS Publications Warehouse

Barbie, Dana L.; Kasmarek, Mark C.; Campodonico, Al

1993-01-01

This report is one in a series of reports that annually depict altitudes of water levels since 1977, the most recent of which (Barbie and others, 1991) presented maps of the altitudes of water levels for 1990.  This report was prepared in cooperation with the City of Houston and the Harris-Galveston Coastal Subsidence District, and preents approximate altitudes of water levels in wells in the Chicot and Evangeline aquifers, in the Houston area, January-February 1991.

Scientific Approach for Optimising Performance, Health and Safety in High-Altitude Observatories

NASA Astrophysics Data System (ADS)

Böcker, Michael; Vogy, Joachim; Nolle-Gösser, Tanja

2008-09-01

The ESO coordinated study “Optimising Performance, Health and Safety in High-Altitude Observatories” is based on a psychological approach using a questionnaire for data collection and assessment of high-altitude effects. During 2007 and 2008, data from 28 staff and visitors involved in APEX and ALMA were collected and analysed and the first results of the study are summarised. While there is a lot of information about biomedical changes at high altitude, relatively few studies have focussed on psychological changes, for example with respect to performance of mental tasks, safety consciousness and emotions. Both, biomedical and psychological changes are relevant factors in occupational safety and health. The results of the questionnaire on safety, health and performance issues demonstrate that the working conditions at high altitude are less detrimental than expected.

Altitude transitions in energy climbs

NASA Technical Reports Server (NTRS)

Weston, A. R.; Cliff, E. M.; Kelley, H. J.

1982-01-01

The aircraft energy-climb trajectory for configurations with a sharp transonic drag rise is well known to possess two branches in the altitude/Mach-number plane. Transition in altitude between the two branches occurs instantaneously, a 'corner' in the minimum-time solution obtained with the energy-state model. If the initial and final values of altitude do not lie on the energy-climb trajectory, then additional jumps (crude approximations to dives and zooms) are required at the initial and terminal points. With a singular-perturbation approach, a 'boundary-layer' correction is obtained for each altitude jump, the transonic jump being a so-called 'internal' boundary layer, different in character from the initial and terminal layers. The determination of this internal boundary layer is examined and some computational results for an example presented.

Simulation and analysis of atmospheric transmission performance in airborne Terahertz communication

NASA Astrophysics Data System (ADS)

Pan, Chengsheng; Shi, Xin; Liu, Chengyang; Wang, Xue; Ding, Yuanming

2018-02-01

For the special meteorological condition of high altitude transmission; first the influence of atmospheric turbulence on the Terahertz wireless communication is analyzed, and the atmospheric constants model with increase in height is given. On this basis, the relationship between the flicker index and the high altitude horizon transmission distance of the Terahertz wave is analyzed by simulation. Then, through the analysis of high altitude path loss and noise, the high altitude wireless link model is built. Finally, the link loss budget is given according to the current Terahertz device parameters, and bit error rate (BER) performance of on-off keyed modulation (OOK) and pulse position modulation (PPM) in four Terahertz frequency bands is compared and analyzed. All these above provided theoretical reference for high-altitude Terahertz wireless communication transmission.

[Quality of sleep and periodic breathing in healthy individuals working at an altitude of 3700 meters].

PubMed

Pływaczewski, R; Pałasiewicz, G; Sarybaev, A S; Le Roux, J; Usupbaeva, D A; Nowiński, A; Mirrakhimov, M M; Zieliński, J

1999-02-01

We performed full polysomnography (PSG) in 7 healthy miners of Kyrghyz origin (mean age 25 +/- 6 years) working in 2 weeks shifts at Kumtor gold mines at the elevation of 4200 m. They slept in comfortable dormitories situated at 3700 m. To avoid acute mountain sickness all subjects received acetazolamide 3 x 0.25 daily during 2 days preceding ascent and during 2 days at altitude: PSG was performed three times: at 760 m (1) and on the 1st (2) and 7th night (3) after rapid ascent (aircraft) to high altitude using SomnoTrac 4250 sleep laboratory. We found that sleep efficiency was good at lowland and in the mountains averaging 81.79% and 84% respectively. Although there were no significant differences in percentage of sleep stages and of total sleep time between lowland and both nights at high altitude, arousals and awakenings were more frequent in the mountains. Episodes of periodic breathing (PB) appeared at high altitude. There was a large individual variability in PB on both nights at altitude. The time spent in PB ranged from 4 to 30 minutes during the first night at altitude and from 3 to 17 minutes during the second one. PB appeared mainly during non-REM sleep and aggravated arterial blood desaturation.

A Computational Study to Investigate the Effect of Altitude on Deteriorated Engine Performance

NASA Astrophysics Data System (ADS)

Koh, W. C.; Mazlan, N. M.; Rajendran, P.; Ismail, M. A.

2018-05-01

This study presents an investigation on the effect of operational altitudes on the performance of the deteriorated engine. A two-spool high bypass ratio turbofan engine is used as the test subject for this study. The engine is modelled in Gas Turbine Simulation Program (GSP) based on an existing engine model from literature. Real flight data were used for the validation. Deterioration rate of 0.1% per day is applied for all turbofan components engine. The simulation is performed by varying the altitude from sea level until 9000m. Results obtained show reduction in air mass flow rate and engine thrust as altitude increases. The reduction in air mass flow rate is due to the lower air density at higher altitude hence reduces amount of engine thrust. At 1000m to 4000m, thrust specific fuel consumption (TSFC) of the engine is improved compared to sea level. However depleted in TSFC is shown when the aircraft flies at altitude higher than 4000m. At this altitude, the effect of air density is dominant. As a result, the engine is required to burn more fuel to provide a higher thrust to sustain the aircraft speed. More fuel is consumed hence depletion in TSFC is obtained.

Effect of yield curves and porous crush on hydrocode simulations of asteroid airburst

NASA Astrophysics Data System (ADS)

Robertson, D. K.; Mathias, D. L.

2017-03-01

Simulations of asteroid airburst are being conducted to obtain best estimates of damage areas and assess sensitivity to variables for asteroid characterization and mitigation efforts. The simulations presented here employed the ALE3D hydrocode to examine the breakup and energy deposition of asteroids entering the Earth's atmosphere, using the Chelyabinsk meteor as a test case. This paper examines the effect of increasingly complex material models on the energy deposition profile. Modeling the meteor as a rock having a single strength can reproduce airburst altitude and energy deposition reasonably well but is not representative of real rock masses (large bodies of material). Accounting for a yield curve that includes different tensile, shear, and compressive strengths shows that shear strength determines the burst altitude. Including yield curves and compaction of porous spaces in the material changes the detailed mechanics of the breakup but only has a limited effect on the burst altitude and energy deposition. Strong asteroids fail and create peak energy deposition close to the altitude at which ram dynamic pressure equals the material strength. Weak asteroids, even though they structurally fail at high altitude, require the increased pressure at lower altitude to disrupt and disperse the rubble. As a result, a wide range of weaker asteroid strengths produce peak energy deposition at a similar altitude.

Early history of high-altitude physiology.

PubMed

West, John B

2016-02-01

High-altitude physiology can be said to have begun in 1644 when Torricelli described the first mercury barometer and wrote the immortal words "We live submerged at the bottom of an ocean of the element air." Interestingly, the notion of atmospheric pressure had eluded his teacher, the great Galileo. Blaise Pascal was responsible for describing the fall in pressure with increasing altitude, and Otto von Guericke gave a dramatic demonstration of the enormous force that could be developed by atmospheric pressure. Robert Boyle learned of Guericke's experiment and, with Robert Hooke, constructed the first air pump that allowed small animals to be exposed to a low pressure. Hooke also constructed a small low-pressure chamber and exposed himself to a simulated altitude of about 2400 meters. With the advent of ballooning, humans were rapidly exposed to very low pressures, sometimes with tragic results. For example, the French balloon, Zénith, rose to over 8000 m, and two of the three aeronauts succumbed to the hypoxia. Paul Bert was the first person to clearly state that the deleterious effects of high altitude were caused by the low partial pressure of oxygen (PO2), and later research was accelerated by high-altitude stations and expeditions to high altitude. © 2015 New York Academy of Sciences.

A High-Altitude Site Survey for SOFIA

NASA Astrophysics Data System (ADS)

Haas, Michael R.; Pfister, Leonhard

1998-03-01

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a modified Boeing 747-SP equipped with a 2.5 m telescope dedicated to astronomical research. Currently under joint development by the US (NASA) and Germany (DLR), it is scheduled to begin operations in late 2001. The ability of SOFIA to carry out its mission will depend strongly on the meteorological conditions at and above flight altitudes in the vicinity of its home base. The most important meteorological factors are the frequency of high-altitude clouds and the magnitude of the water vapor overburdens. This paper performs a high-altitude site survey by gathering together the best available meteorological data, defining metrics, and evaluating them for a variety of sites. These metrics are found to corroborate past airborne experience and to be consistent with well-known global circulation patterns, convection, and upper tropospheric dynamics. They indicate that there are significant variations in the weather at SOFIA flight altitudes. Particularly in summer, some continental US sites are shown to be worse than Hawaii, where high-altitude cirrus clouds and the associated moisture have historically caused significant losses in the amount and quality of the astronomical data collected by NASA's Kuiper Airborne Observatory. SOFIA's planned home base, Moffett Field, CA, is found to have excellent high-altitude weather and to be one of the best continental US sites.

Correlation Of Giant Nuclei With Cloud Droplet Concentration

NASA Astrophysics Data System (ADS)

Jha, V.; Hudson, J. G.; Noble, S.

2011-12-01

The effect of giant nuclei (GN; larger than 1 micrometer particles produced by wind on the ocean surface) on warm rain has been debated for decades. During RICO (Rain in Cumulus over the Ocean) Hudson et al. (2011) found a negative correlation (R) between CCN concentrations at 1% supersaturation (S) and large cloud droplet concentrations (Fig. 1A). This reversal from positive R for CCN with total (or small) cloud droplet concentrations (left side of Fig. 1A) was explained by the greater competition for condensate, which thus limits droplet sizes when CCN concentrations are higher. The negative R increased in magnitude with altitude, and the droplet size where the maximum negative R occurred increased with altitude (Fig. 1A). However, at all altitudes this negative R decreased in magnitude for even larger cloud and drizzle drops (right side of Fig. 1A except highest altitude). The decrease in magnitude of the negative R was greater for increasing drop sizes at higher altitudes. Thus, at the higher altitudes, R for CCN with large drizzle drops was of low negative magnitude and even positive at the highest RICO altitudes. The disparity between CCN and drizzle drop concentrations precluded a causal relationship. But the high R between GN and drizzle drop concentrations at the highest altitudes (Fig. 1B) and the comparable concentrations indicated that GN were engendering drizzle. This is supported by the increasing R with altitude of the GN-drizzle drop R (right side of Fig. 1B). The conclusion of a GN-drizzle connection is also supported by the fact that CCN concentrations should inhibit drizzle. This analysis of Hudson et al. (2011) is here expanded to include correlations of CCN concentrations at lower S with cloud and drizzle drop concentrations to investigate intermediate relationships; i.e., between large nuclei (i.e., 0.1-1 micrometer; critical S 0.1-0.01%) and drizzle drop concentrations. A shortcoming of Hudson et al. (2011) was the small number of high altitude flights, which limited the significance of the R values. The very recent (July 2011) ICE-T project was a similar study in the same region (Caribbean). The greater number of high altitude cloud measurements during the summer season should provide better statistics to test the GN warm rain hypothesis.

Aqueous Chemistry in the Clouds of Venus: A Possible Source for the UV Absorber

NASA Astrophysics Data System (ADS)

Baines, Kevin H.; Delitsky, M. L.

2013-10-01

The identity and cause of the UV absorber near the Venusian cloudtops 62-70 km altitude) has been an enduring mystery. Given the role of sulfur in Venus’s atmosphere, where, somewhat analogous to water on Earth, it cycles through gas, liquid, and (possibly) solid phases in the atmosphere, it has been a prime suspect as at least a key component, perhaps as long-lived solid poly-sulfur aerosols, Sn, where n > 4. However, the narrow range of altitudes inhabited by the UV absorber (thought to form and reside primarily above 62 km altitude) seems incompatible with Sn, which should vertically disperse after formation. Here, we point to another process that could lead to somewhat more exotic chemistries that favor formation and sequestration at high altitudes: Aqueous chemistry within H2SO4-nH2O cloud particles. Due to (1) the decrease of temperature and (2) the increase in the fraction of water (“n” in the previous formula) of each cloud droplet with altitude, high-altitude particles near the cloudtops are - via the “heterogeneous uptake” process - significantly more capable of capturing and concentrating trace gases, in particular HCl. For example, the heterogeneous uptake of HCl in H2SO4 droplets near the 65-km cloudtops is at least three times greater than that found in the middle of the clouds near 55 km altitude. Other factors such as local mixing ratios and the concentration of other solvents in the droplet also modify the uptake. Within the cloud droplets, solution chemistry between HCl and H2SO4 may lead to the formation of chlorosulfonic acid, ClSO3H, which is a weak acid that readily breaks down into other species, such as SO2Cl2 (sulfuryl chloride) and SOCl2 (thionyl chloride). Together, these three materials have UV-blue absorptions at 0.21, 0.29, 0.39 and 0.47 micron. Thus, H2SO4 aerosols at high altitudes may take on lasting UV absorption characteristics, dependent on temperature (altitude) and other conditions, Balloons floating at benign Earth-surface-like temperature/pressure conditions near 56-km altitude may be able to sample such aerosols and their complex contents as measured in periodic downdrafts of materials from higher altitudes.

Bovine fasciolosis at increasing altitudes: Parasitological and malacological sampling on the slopes of Mount Elgon, Uganda

PubMed Central

2012-01-01

Background To clarify the extent and putative transmission zone of bovine fasciolosis on the slopes of Mount Elgon, Uganda, conjoint parasitological and malacological surveys, inclusive of inspection of animals at slaughter, were undertaken at increasing altitudes. Results A total of 239 cattle were sampled across eight locations ranging in elevation from 1112-2072 m. Faecal material was examined for presence of Fasciola eggs and sera were tested by ELISA for antibodies against Fasciola antigens. Bolstering this, 38 cattle at slaughter from 2 abattoir sites at 1150 m and 1947 m were inspected; in addition, wild buffalo stool (n = 10) opportunistically picked within Mount Elgon National Park (MENP) at 3640 m was examined. By faecal egg detection, prevalence of Fasciola gigantica at low (<1500 m) and high (>1500 m) altitude sites was 43.7% (95% CI 35.4-52.2) and 1.1% (95% CI 0.0-6.0), respectively, while by ELISA was much higher, low altitude - 77.9% (95% CI 69.7-85.4) and high altitude - 64.5% (95% CI 51.3-76.3). The decline in prevalence with increasing altitude was corroborated by abattoir sampling. Thirty seven aquatic habitats, ranging from 1139-3937 m in altitude were inspected for freshwater snails, 12 of which were within MENP. At lower altitudes, Lymnaea (Radix) natalensis was common, and often abundant, but at higher altitudes became much rarer ceasing to be found above 1800 m. On the other hand, Lymnaea (Galba) truncatula was found only at altitudes above 3000 m and within MENP alone. The snail identifications were confirmed by DNA analysis of the ribosomal 18S gene. Conclusions Active infections of F. gigantica in cattle are common in lower altitude settings but appear to diminish with increasing elevation. This is likely due to a growing paucity of intermediate hosts, specifically populations of L. natalensis for which a natural boundary of 1800 m appeared. Although F. hepatica was not encountered, the presence of several populations of L. truncatula at elevations over 3000 m point towards a potential transmission zone within MENP should this parasite be introduced. PMID:22958402

Investigation of the I-40 Jet-Propulsion Engine in the Cleveland Altitude Wind Tunnel. V - Operational Characteristics. 5; Operational Characteristics

NASA Technical Reports Server (NTRS)

Golladay, Richard L.; Gendler, Stanley L.

1947-01-01

An investigation has been conducted in the Cleveland altitude wind tunnel to determine the operational characteristics of the I-40 jet-propulsion engine over a range of pressure altitudes from 10,000 to 50,000 feet and ram-pressure ratios from 1.00 to 1.76. Engine operational data were obtained with the engine in the standard configuration and with various modifications of the fuel system, the electrical system, and the combustion chambers. The effects of altitude and airspeed on operating speed range, starting, windmilli.ng, acceleration, speed regulation, cooling, and vibration of the standard and modified engines were determined, and damage to parts was noted. Maximum engine speed was obtainable at all altitudes and airspeeds wi th each fuel-control system investigated. The minimum idling speed was raised by increases in altitude and airspeed. The lowest minimum stable speeds were obtained with the standard configuration using 40-gallon nozzles with individual metering plugs. The engine was started normally at altitudes as high as 20,000 feet with all of the fuel systems and ignition combinations except one. Ignition at 70,000 feet was difficult and, although successful ignition occurred, acceleration was slow and usually characterized by excessive tail-pipe temperature. During windmilling investigations of the engine equipped with the standard fuel system, the engine could not be started at ram-pressure ratios of 1.1 to 1.7 at altitudes of 10,000, 20,000 and 30,000 feet. When equipped with the production barometric and Monarch 40-gallon nozzles, the engine accelerated in 12 seconds from an engine speed of 6000 rpm to 11,000 rpm at 20,000 feet and an average tail-pipe temperature of 11000 F. At the same altitude and temperature, all the engine configurations had approximately the same rate of acceleration. The Woodward governor produced the safest accelerations, inasmuch as it could be adjusted to automatically prevent acceleration blow out. The engine speed was held constant by the Woodward governor and the Edwards regulator during simulated dives and climbs at constant throttle position. The bearing cooling system was satisfactory at all altitudes and airspeeds. The engines operated without serious failure, although the exhaust cone, the tail pipe, and the airplane fuselage were damaged during altitude starts.

Long-Duration Altitude-Controlled Balloons for Venus: A Feasibility Study Informed by Balloon Flights in Remote Environments on Earth

NASA Astrophysics Data System (ADS)

Voss, P. B.; Nott, J.; Cutts, J. A.; Hall, J. L.; Beauchamp, P. M.; Limaye, S. S.; Baines, K. H.; Hole, L. R.

2013-12-01

In situ exploration of the upper atmosphere of Venus, approximately 65-77 km altitude, could answer many important questions (Limaye 2013, Crisp 2013). This region contains a time-variable UV absorber of unknown composition that controls many aspects of the heat balance on Venus. Understanding the composition and dynamics of this unknown absorber is an important science goal; in situ optical and chemical measurements are needed. However, conventional approaches do not provide access to this altitude range, repeated traverses, and a mission lifetime of several months needed to effectively carry out the science. This paper examines concepts for altitude-controlled balloons not previously flown on planetary missions that could potentially provide the desired measurements. The concepts take advantage of the fact that at 60 km altitude, for example, the atmospheric density on Venus is about 40% of the sea-level density on earth and the temperature is a moderate 230 K. The solar flux is approximately double that on earth, creating some thermal challenges, but making photovoltaic power highly effective. Using a steady-state thermodynamic model and flight data from Earth, we evaluate the suitability of two types of altitude-controlled balloons for a potential mission on Venus. Such balloons could repeatedly measure profiles, avoid diurnal temperature extremes, and navigate using wind shear. The first balloon design uses air ballast (AB) whereby ambient air can be compressed into or released from a constant-volume balloon, causing it to descend or ascend accordingly. The second design uses lift-gas compression (LGC) to change the volume of a zero-pressure balloon, thereby changing its effective density and altitude. For an altitude range of 60-75 km on Venus, we find that the superpressure volume for a LGC balloon is about 5% of that needed for an AB balloon while the maximum pressurization is the same for both systems. The compressor work per km descent of the LGC balloon is about 10% of the AB balloon, largely due to the much lower flow rate. The LGC balloon must compress some lift gas at sunrise, but this can be managed by one of several strategies. We conclude that while the weight constraints are likely to be significant, LGC altitude-controlled balloons may be feasible for accessing the 60 to 75 km altitude range on Venus. The underlying concept of balloons on Venus was proven by the Soviet Union's successful deployment of their two superpressure VEGA balloons in 1981 operating at a fixed altitude near 55 km. Superpressure balloon concepts for similar altitudes and larger payloads have since been proposed for NASA's Discovery program and ESA's Cosmic Visions program. The LGC balloon would add a zero-pressure envelope and a compressor to the established superpressure design, allowing it to ascend above the deployment altitude and realize lossless altitude control over a range of several scale heights. The thermodynamic equations, flight data, and conceptual analysis presented are intended to foster further discussion about the feasibility and potential benefits of a balloon mission to Venus.

The influence of altitude and landforms on some biochemical and hematological parameters in Ouled Djellal ewes from arid area of South East Algeria.

PubMed

Titaouine, Mohammed; Meziane, Toufik

2015-01-01

This study was conducted on Ouled Djellal ewes in arid area of south-east Algeria in order to reveal the influence of altitude and landforms on some hematological and biochemical parameters. A total of 160 ewes having 3-5 years of age, multiparous, non-pregnant, non-lactating and reared in arid areas of South East Algeria were included. Blood samples were divided according to factors of altitude and landform (plain region at 150 m above sea level, tableland region at 600 m above sea level and mountain region at 1000 m above sea level). The whole blood was analyzed for hematology, and plasma samples for biochemical analysis. The study found lowest glucose concentrations were detected in tableland region at 600 m. In plain region at 150 m, ewes had a higher (p<0.01) concentration of cholesterol and triglyceride. Furthermore, a higher concentration of total proteins (p<0.01) and urea (p<0.05) were detected in plain region at 150 m. The average blood creatinine concentration in mountain ewes at 1000 m and tableland ewes at 600 m were higher (p<0.05) that in plain ewes at 150 m. The highest calcium concentration was found at the altitude of 150 m and the lowest at the altitude of 1000 m (1.12±0.35 mmol/L vs. 0.52±0.03 mmol/L). Phosphorus levels were higher at altitudes of 150 m than at the altitude of 600 m and 1000 m (0.93±0.42 mmol/L vs. 0.68±0.54 mmol/L, 0.23±0.01 mmol/L). The highest hemoglobin concentration and value of hematocrit were detected in mountain ewes at the altitude of 1000 m (120.61 g/L, 40%) and the lowest at the altitude of 150 m (73.2 g/L, 31%) (p<0.001). We concluded that hematological and biochemical parameters in Ouled Djellel ewes reared in arid area may be affected by altitude and landforms.

Role of Arcuate Nucleus in the Regulation of Feeding Behavior in the Process of Altitude Acclimatization in Rats.

PubMed

Liu, Xiang-Wen; Yin, Jie; Ma, Qi-Sheng; Qi, Chu-Chu; Mu, Ji-Ying; Zhang, Lang; Gao, Li-Ping; Jing, Yu-Hong

2017-09-01

Liu, Xiang-Wen, Jie Yin, Qi-Sheng Ma, Chu-Chu Qi, Ji-Ying Mu, Lang Zhang, Li-Ping Gao, and Yu-Hong Jing. Role of arcuate nucleus in the regulation of feeding behavior in the process of altitude acclimatization in rats. High Alt Med Biol. 18:234-241, 2017.-Highly efficient energy utilization and metabolic homeostasis maintenance rely on neuromodulation. Altitude exposure is known to stimulate neuroendocrine systems to respond to acute hypoxia and adaptive acclimatization. However, limited data on how the adaptive regulation of the arcuate nucleus performs in the process of altitude acclimatization are available. In the present study, male Sprague Dawley rats were transported to Huashixia, Qinghai (with an altitude of 4400 m) from Xian (with an altitude of 300 m) by air; rats were consistently raised in Xian as control. Food uptake and body weight were measured consecutively after being subjected to high-altitude condition. Contents of plasma leptin and ghrelin were analyzed by the Enzyme Linked Immunosorbent Assay (ELISA) Kits. Brain coronal sections were obtained, and neuropeptide Y (NPY), proopiomelanocotin (POMC), and c-fos immunoreactivity in arcuate nucleus were observed. Arcuate nucleus was isolated from the hypothalamus, and the mRNA of NPY and POMC were measured by quantitative real-time polymerase chain reaction. Our results showed both food consumption and body weight decreased in the high plateau compared with rats raised in the low-altitude condition. Plasma leptin increased at the early stage, and ghrelin decreased at a later stage after reaching the high plateau. The peak of c-fos immunoreactivity in the arcuate nucleus was at day 3 after reaching the high plateau. The expression level of NPY increased, and POMC decreased in the arcuate nucleus at day 7 after reaching the high plateau compared with the plain control group. These results indicate that the arcuate nucleus of hypothalamus performs an important function in regulating feeding behavior during altitude acclimatization. Our study suggested that altitude acclimation is regulated by the hypothalamus that received leptin and ghrelin signals to response by its microcircuit, including NPY- and POMC-neurons in the arcuate nucleus.

Simulated Altitude Investigation of Stewart-Warner Model 906-B Combustion Heater

NASA Technical Reports Server (NTRS)

Ebersbach, Frederick R.; Cervenka, Adolph J.

1947-01-01

An investigation has been conducted to determine thermal and pressure-drop performance and the operational characteristics of a Stewart-Warner model 906-B combustion heater. The performance tests covered a range of ventilating-air flows from 500 to 3185 pounds per hour, combustion-air pressure drops from 5 to 35 inches of water, and pressure altitudes from sea level to 41,000 feet. The operational characteristics investigated were the combustion-air flows for sustained combustion and for consistent ignition covering fuel-air ratios ranging from 0.033 to 0.10 and pressure altitudes from sea level to 45,000 feet. Rated heat output of 50,000 Btu per hour was obtained at pressure altitudes up to 27,000 feet for ventilating-air flows greater than 800 pounds per hour; rated output was not obtained at ventilating-air flow below 800 pounds per hour at any altitude. The maximum heater efficiency was found to be 60.7 percent at a fuel-air ratio of 0.050, a sea-level pressure altitude, a ventilating-air temperature of 0 F, combustion-air temperature of 14 F, a ventilating-air flow of 690 pounds per hour, and a combustion-air flow of 72.7 pounds per hour. The minimum combustion-air flow for sustained combustion at a pressure altitude of 25,000 feet was about 9 pounds per hour for fuel-air ratios between 0.037 and 0.099 and at a pressure altitude of 45,000 feet increased to 18 pounds per hour at a fuel-air ratio of 0.099 and 55 pounds per hour at a fuel-air ratio of 0.036. Combustion could be sustained at combustion-air flows above values of practical interest. The maximum flow was limited, however, by excessively high exhaust-gas temperature or high pressure drop. Both maximum and minimum combustion-air flows for consistent ignition decrease with increasing pressure altitude and the two curves intersect at a pressure altitude of approximately 25,000 feet and a combustion-air flow of approximately 28 pounds per hour.

Respiratory parameters at varied altitudes in intermittent mining work.

PubMed

Bacaloni, Alessandro; Zamora Saà, Margarita Cecilia; Sinibaldi, Federica; Steffanina, Alessia; Insogna, Susanna

2018-01-07

Workers in the mining industry in altitude are subjected to several risk factors, e.g., airborne silica and low barometric pressure. The aim of this study has been to assess the risks for this work category, evaluating single risk factors as airborne silica, altitude and work shift, and relating them with cardiovascular and ventilatory parameters. Healthy miners employed in a mining company, Chile, working at varied altitudes, and subjected to unusual work shifts, were evaluated. Cardiovascular and respiratory parameters were investigated. Exposure to airborne silica was evaluated and compared to currently binding exposure limits. At varied altitudes and work shifts, alterations emerged in haemoglobin, ventilation and respiratory parameters, related to employment duration, due to compensatory mechanisms for hypoxia. Haemoglobin increased with altitude, saturation fell down under 90% in the highest mines. The multiple linear regression analysis showed a direct relationship, in the higher mine, between years of exposure to altitude and increased forced vital capacity percent (FVC%), and forced expiratory volume in 1 s (FEV1). An inverse relationship emerged between forced vital capacity (FVC) and years of exposure to airborne silica. In the workplace Mina Subterrànea (MT-3600), statistically significant inverse relationship emerged between the Tiffeneau index and body weight. The working conditions in the mining industry in altitude appeared to be potentially pathogenic; further investigations should be realized integrating risk assessment protocols even in consideration of their undeniable unconventionality. Int J Occup Med Environ Health 2018;31(2):129-138. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Position statement--altitude training for improving team-sport players' performance: current knowledge and unresolved issues.

PubMed

Girard, Olivier; Amann, Markus; Aughey, Robert; Billaut, François; Bishop, David J; Bourdon, Pitre; Buchheit, Martin; Chapman, Robert; D'Hooghe, Michel; Garvican-Lewis, Laura A; Gore, Christopher J; Millet, Grégoire P; Roach, Gregory D; Sargent, Charli; Saunders, Philo U; Schmidt, Walter; Schumacher, Yorck O

2013-12-01

Despite the limited research on the effects of altitude (or hypoxic) training interventions on team-sport performance, players from all around the world engaged in these sports are now using altitude training more than ever before. In March 2013, an Altitude Training and Team Sports conference was held in Doha, Qatar, to establish a forum of research and practical insights into this rapidly growing field. A round-table meeting in which the panellists engaged in focused discussions concluded this conference. This has resulted in the present position statement, designed to highlight some key issues raised during the debates and to integrate the ideas into a shared conceptual framework. The present signposting document has been developed for use by support teams (coaches, performance scientists, physicians, strength and conditioning staff) and other professionals who have an interest in the practical application of altitude training for team sports. After more than four decades of research, there is still no consensus on the optimal strategies to elicit the best results from altitude training in a team-sport population. However, there are some recommended strategies discussed in this position statement to adopt for improving the acclimatisation process when training/competing at altitude and for potentially enhancing sea-level performance. It is our hope that this information will be intriguing, balanced and, more importantly, stimulating to the point that it promotes constructive discussion and serves as a guide for future research aimed at advancing the bourgeoning body of knowledge in the area of altitude training for team sports.

Position statement—altitude training for improving team-sport players’ performance: current knowledge and unresolved issues

PubMed Central

Girard, Olivier; Amann, Markus; Aughey, Robert; Billaut, François; Bishop, David J; Bourdon, Pitre; Buchheit, Martin; Chapman, Robert; D'Hooghe, Michel; Garvican-Lewis, Laura A; Gore, Christopher J; Millet, Grégoire P; Roach, Gregory D; Sargent, Charli; Saunders, Philo U; Schmidt, Walter; Schumacher, Yorck O

2013-01-01

Despite the limited research on the effects of altitude (or hypoxic) training interventions on team-sport performance, players from all around the world engaged in these sports are now using altitude training more than ever before. In March 2013, an Altitude Training and Team Sports conference was held in Doha, Qatar, to establish a forum of research and practical insights into this rapidly growing field. A round-table meeting in which the panellists engaged in focused discussions concluded this conference. This has resulted in the present position statement, designed to highlight some key issues raised during the debates and to integrate the ideas into a shared conceptual framework. The present signposting document has been developed for use by support teams (coaches, performance scientists, physicians, strength and conditioning staff) and other professionals who have an interest in the practical application of altitude training for team sports. After more than four decades of research, there is still no consensus on the optimal strategies to elicit the best results from altitude training in a team-sport population. However, there are some recommended strategies discussed in this position statement to adopt for improving the acclimatisation process when training/competing at altitude and for potentially enhancing sea-level performance. It is our hope that this information will be intriguing, balanced and, more importantly, stimulating to the point that it promotes constructive discussion and serves as a guide for future research aimed at advancing the bourgeoning body of knowledge in the area of altitude training for team sports. PMID:24282213

[Geographic Altitude of Residence and Alcohol Dependence in a Peruvian Population].

PubMed

Quiñones-Laveriano, Dante Manuel; Espinoza-Chiong, César; Scarsi-Mejia, Ottavia; Rojas-Camayo, José; Mejia, Christian Richard

2016-01-01

The aim of this study was to determine the association between alcohol dependence and altitude of residence in 11 villages in two high altitude areas of Peru. An analytical cross-sectional study was performed using a survey conducted by physicians in primary health care in 11 villages until 2013, that were divided into low altitude (≤2500m asl (above sea level)), and high altitude (>2500m asl) areas. The CAGE test for alcoholism (cut point, ≥2) was applied to those who responded positively when asked if they consumed alcohol. Statistical associations were obtained with generalised linear models Of the 737 participants, 51% were women and the median age was 36 years [interquartile range, 25-50], 334 (45%) lived at low altitude, and 113 (15%) had alcohol dependence. The highest frequency of alcoholism was positively associated with being a village considered extremely poor (Likelihood Ratio (LP)=2.42; 95%CI, 1.40-4.19), while being female (LP=0.44; 95%CI, 0.23-0.89) and residing at high altitude (LP=0.15; 95%CI, 0.07-0.31) were negatively associated. These were adjusted for nine socio-occupational and pathological variables. According to these data, there is a higher frequency of alcohol dependence in being, male, extremely poor, and residing at low altitude. These results should be taken into account by professionals who work in primary care and those involved in mental health care, because of their implications in society. Copyright © 2015 Asociación Colombiana de Psiquiatría. Publicado por Elsevier España. All rights reserved.

Heart rate and respiratory rhythm dynamics on ascent to high altitude.

PubMed Central

Lipsitz, L. A.; Hashimoto, F.; Lubowsky, L. P.; Mietus, J.; Moody, G. B.; Appenzeller, O.; Goldberger, A. L.

1995-01-01

OBJECTIVE--To investigate the alterations in autonomic control of heart rate at high altitude and to test the hypothesis that hypoxaemic stress during exposure to high altitude induces non-linear, periodic heart rate oscillations, similar to those seen in heart failure and the sleep apnoea syndrome. SUBJECTS--11 healthy subjects aged 24-64. MAIN OUTCOME MEASURES--24 hour ambulatory electrocardiogram records obtained at baseline (1524 m) and at 4700 m. Simultaneous heart rate and respiratory dynamics during 2.5 hours of sleep by fast Fourier transform analysis of beat to beat heart rate and of an electrocardiographically derived respiration signal. RESULTS--All subjects had resting hypoxaemia at high altitude, with an average oxyhaemoglobin saturation of 81% (5%). There was no significant change in mean heart rate, but low frequency (0.01-0.05 Hz) spectral power was increased (P < 0.01) at high altitude. Time series analysis showed a complex range of non-linear sinus rhythm dynamics. Striking low frequency (0.04-0.06 Hz) heart rate oscillations were observed during sleep in eight subjects at high altitude. Analysis of the electrocardiographically derived respiration signal indicated that these heart rate oscillations correlated with low frequency respiratory oscillations. CONCLUSIONS--These data suggest (a) that increased low frequency power during high altitude exposure is not simply attributable to increased sympathetic modulation of heart rate, but relates to distinctive cardiopulmonary oscillations at approximately 0.05 Hz and (b) that the emergence of periodic heart rate oscillations at high altitude is consistent with an unstable cardiopulmonary control system that may develop on acute exposure to hypoxaemic stress. PMID:7488453

Climatic Control on Plant and Soil δ13C along an Altitudinal Transect of Lushan Mountain in Subtropical China: Characteristics and Interpretation of Soil Carbon Dynamics

PubMed Central

Du, Baoming; Liu, Chunjiang; Kang, Hongzhang; Zhu, Penghua; Yin, Shan; Shen, Guangrong; Hou, Jingli; Ilvesniemi, Hannu

2014-01-01

Decreasing temperature and increasing precipitation along altitude gradients are typical mountain climate in subtropical China. In such a climate regime, identifying the patterns of the C stable isotope composition (δ13C) in plants and soils and their relations to the context of climate change is essential. In this study, the patterns of δ13C variation were investigated for tree leaves, litters, and soils in the natural secondary forests at four altitudes (219, 405, 780, and 1268 m a.s.l.) in Lushan Mountain, central subtropical China. For the dominant trees, both leaf and leaf-litter δ13C decreased as altitude increased from low to high altitude, whereas surface soil δ13C increased. The lower leaf δ13C at high altitudes was associated with the high moisture-related discrimination, while the high soil δ13C is attributed to the low temperature-induced decay. At each altitude, soil δ13C became enriched with soil depth. Soil δ13C increased with soil C concentrations and altitude, but decreased with soil depth. A negative relationship was also found between O-alkyl C and δ13C in litter and soil, whereas a positive relationship was observed between aromatic C and δ13C. Lower temperature and higher moisture at high altitudes are the predominant control factors of δ13C variation in plants and soils. These results help understand C dynamics in the context of global warming. PMID:24466099

Heart rate and respiratory rhythm dynamics on ascent to high altitude

NASA Technical Reports Server (NTRS)

Lipsitz, L. A.; Hashimoto, F.; Lubowsky, L. P.; Mietus, J.; Moody, G. B.; Appenzeller, O.; Goldberger, A. L.

1995-01-01

OBJECTIVE--To investigate the alterations in autonomic control of heart rate at high altitude and to test the hypothesis that hypoxaemic stress during exposure to high altitude induces non-linear, periodic heart rate oscillations, similar to those seen in heart failure and the sleep apnoea syndrome. SUBJECTS--11 healthy subjects aged 24-64. MAIN OUTCOME MEASURES--24 hour ambulatory electrocardiogram records obtained at baseline (1524 m) and at 4700 m. Simultaneous heart rate and respiratory dynamics during 2.5 hours of sleep by fast Fourier transform analysis of beat to beat heart rate and of an electrocardiographically derived respiration signal. RESULTS--All subjects had resting hypoxaemia at high altitude, with an average oxyhaemoglobin saturation of 81% (5%). There was no significant change in mean heart rate, but low frequency (0.01-0.05 Hz) spectral power was increased (P < 0.01) at high altitude. Time series analysis showed a complex range of non-linear sinus rhythm dynamics. Striking low frequency (0.04-0.06 Hz) heart rate oscillations were observed during sleep in eight subjects at high altitude. Analysis of the electrocardiographically derived respiration signal indicated that these heart rate oscillations correlated with low frequency respiratory oscillations. CONCLUSIONS--These data suggest (a) that increased low frequency power during high altitude exposure is not simply attributable to increased sympathetic modulation of heart rate, but relates to distinctive cardiopulmonary oscillations at approximately 0.05 Hz and (b) that the emergence of periodic heart rate oscillations at high altitude is consistent with an unstable cardiopulmonary control system that may develop on acute exposure to hypoxaemic stress.

The effect of partial acclimatization to high altitude on loop gain and central sleep apnoea severity.

PubMed

Andrews, Gareth; Ainslie, Philip N; Shepherd, Kelly; Dawson, Andrew; Swart, Marianne; Lucas, Samuel; Burgess, Keith R

2012-07-01

Loop gain is an engineering term that predicts the stability of a feedback control system, such as the control of breathing. Based on earlier studies at lower altitudes, it was hypothesized that acclimatization to high altitude would lead to a reduction in loop gain and thus central sleep apnoea (CSA) severity. This study used exposure to very high altitude to induce CSA in healthy subjects to investigate the effect of partial acclimatization on loop gain and CSA severity. Measurements were made on 12 subjects (age 30 ± 10 years, body mass index 22.8 ± 1.9, eight males, four females) at an altitude of 5050 m over a 2-week period upon initial arrival (days 2-4) and following partial acclimatization (days 12-14). Sleep was studied by full polysomnography, and resting arterial blood gases were measured. Loop gain was measured by the 'duty cycle' method (duration of hyperpnoea/cycle length). Partial acclimatization to high-altitude exposure was associated with both an increase in loop gain (duty cycle fell from 0.60 ± 0.05 to 0.55 ± 0.06 (P = 0.03)) and severity of CSA (apnoea-hypopnoea index increased from 76.8 ± 48.8 to 115.9 ± 20.2 (P = 0.01)), while partial arterial carbon dioxide concentration fell from 29 ± 3 to 26 ± 2 (P = 0.01). Contrary to the results at lower altitudes, at high-altitude loop gain and severity of CSA increased. © 2012 The Authors. Respirology © 2012 Asian Pacific Society of Respirology.

75 FR 16336 - Establishment of Low Altitude Area Navigation Route (T-284); Houston, TX

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-01

... (T-284); Houston, TX AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: This action establishes a low altitude area navigation (RNAV) route, designated T-284, in the Houston... Register a notice of proposed rulemaking (NPRM) to establish low altitude area navigation route T-284 (74...

76 FR 17364 - Airworthiness Directives; Dassault-Aviation Model FALCON 7X Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-29

... a negative distance to the ground despite the aircraft was flying at medium or high altitude. A... despite the aircraft was flying at medium or high altitude. A locked radio-altimeter 1 leads to untimely... certain abnormal conditions while the avionic system switches into landing mode during altitude cruise...

14 CFR 93.307 - Minimum flight altitudes.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Minimum flight altitudes. 93.307 Section 93...) AIR TRAFFIC AND GENERAL OPERATING RULES SPECIAL AIR TRAFFIC RULES Special Flight Rules in the Vicinity of Grand Canyon National Park, AZ § 93.307 Minimum flight altitudes. Except in an emergency, or if...

14 CFR 93.307 - Minimum flight altitudes.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false Minimum flight altitudes. 93.307 Section 93...) AIR TRAFFIC AND GENERAL OPERATING RULES SPECIAL AIR TRAFFIC RULES Special Flight Rules in the Vicinity of Grand Canyon National Park, AZ § 93.307 Minimum flight altitudes. Except in an emergency, or if...

Protective Clothing

DTIC Science & Technology

1975-01-01

WASHINGTON 0 C AEROSPACE TECHNOLOGY DIV HIGH -ALTITUDE PRESSURESUITS AND HERMETICALLY SEALED CABINS FOR STRATOSPHERIC FLIGHTS* (U) DESCRIPTIVE NOTE...TRANS. FROM VESTNIK VOZDUSNNOGO FLOTA, NO. So PP. 48൹, |938. DESCRIPTORS: (*PRESSURE SUITS. USSR)o PRESSURIZED CABINS. HERMETIC SEALS, HIGH ALTITUDE...STRATOSPHERE, BREATHING APPARATUS, OXYGEN EQUIPMENT, REVIEWS, DESIG(U) HIGH -ALTITUDE PRESSURE SUITS AND HERMETICALLY SEALED CABINS FOR STRATOSPHERIC

Reliability of CHAMP Anomaly Continuations

NASA Technical Reports Server (NTRS)

vonFrese, Ralph R. B.; Kim, Hyung Rae; Taylor, Patrick T.; Asgharzadeh, Mohammad F.

2003-01-01

CHAMP is recording state-of-the-art magnetic and gravity field observations at altitudes ranging over roughly 300 - 550 km. However, anomaly continuation is severely limited by the non-uniqueness of the process and satellite anomaly errors. Indeed, our numerical anomaly simulations from satellite to airborne altitudes show that effective downward continuations of the CHAMP data are restricted to within approximately 50 km of the observation altitudes while upward continuations can be effective over a somewhat larger altitude range. The great unreliability of downward continuation requires that the satellite geopotential observations must be analyzed at satellite altitudes if the anomaly details are to be exploited most fully. Given current anomaly error levels, joint inversion of satellite and near- surface anomalies is the best approach for implementing satellite geopotential observations for subsurface studies. We demonstrate the power of this approach using a crustal model constrained by joint inversions of near-surface and satellite magnetic and gravity observations for Maude Rise, Antarctica, in the southwestern Indian Ocean. Our modeling suggests that the dominant satellite altitude magnetic anomalies are produced by crustal thickness variations and remanent magnetization of the normal polarity Cretaceous Quiet Zone.

High Altitude Medical Problems

PubMed Central

Hultgren, Herbert N.

1979-01-01

Increased travel to high altitude areas by mountaineers and nonclimbing tourists has emphasized the clinical problems associated with rapid ascent. Acute mountain sickness affects most sojourners at elevations above 10,000 feet. Symptoms are usually worse on the second or third day after arrival. Gradual ascent, spending one to three days at an intermediate altitude, and the use of acetazolamide (Diamox) will prevent or ameliorate symptoms in most instances. Serious and potentially fatal problems, such as high altitude pulmonary edema or cerebral edema, occur in approximately 0.5 percent to 1.0 percent of visitors to elevations above 10,000 feet—especially with heavy physical exertion on arrival, such as climbing or skiing. Early recognition, high flow oxygen therapy and prompt descent are crucially important in management. Our knowledge of the causes of these and other high altitude problems, such as retinal hemorrhage, systemic edema and pulmonary hypertension, is still incomplete. Even less is known of the effect of high altitudes on medical conditions common at sea level or on the action of commonly used drugs. ImagesFigure 2. PMID:483805

Mobile platform of altitude measurement based on a smartphone

NASA Astrophysics Data System (ADS)

Roszkowski, Paweł; Kowalczyk, Marcin

2016-09-01

The article presents a low cost, fully - functional meter of altitude and pressure changes in a form of mobile application controlled by Android OS (operating system). The measurements are possible due to pressure sensor inserted in majority of latest modern mobile phones, which are known as smartphones. Using their computing capabilities and other equipment components like GPS receiver in connection with data from the sensor enabled authors to create a sophisticated handheld measuring platform with many unique features. One of them is a drawing altitude maps mode in which user can create maps of altitude changes just by moving around examined area. Another one is a convenient mode for altitude measurement. It is also extended with analysis tools which provide a possibility to compare measured values by displaying the data in a form of plots. The platform consists of external backup server, where the user can secure all gathered data. Moreover, the results of measurement's accuracy examination process which was executed after building the solution were shown. At the end, the realized meter of altitude was compared to other popular altimeters, which are available on the market currently.

Geomorphology Classification of Shandong Province Based on Digital Elevation Model in the 1 Arc-second Format of Shuttle Radar Topography Mission Data

NASA Astrophysics Data System (ADS)

Fu, Jundong; Zhang, Guangcheng; Wang, Lei; Xia, Nuan

2018-01-01

Based on gigital elevation model in the 1 arc-second format of shuttle radar topography mission data, using the window analysis and mean change point analysis of geographic information system (GIS) technology, programmed with python modules this, automatically extracted and calculated geomorphic elements of Shandong province. The best access to quantitatively study area relief amplitude of statistical area. According to Chinese landscape classification standard, the landscape type in Shandong province was divided into 8 types: low altitude plain, medium altitude plain, low altitude platform, medium altitude platform, low altitude hills, medium altitude hills, low relief mountain, medium relief mountain and the percentages of Shandong province’s total area are as follows: 12.72%, 0.01%, 36.38%, 0.24%, 17.26%, 15.64%, 11.1%, 6.65%. The results of landforms are basically the same as the overall terrain of Shandong Province, Shandong province’s total area, and the study can quantitatively and scientifically provide reference for the classification of landforms in Shandong province.

A New Analysis of the Spectra Obtained by the Venera Missions in the Venusian Atmosphere. I. The Analysis of the Data Received from the Venera-11 Probe at Altitudes Below 37 km in the 0.44 0.66 µm Wavelength Range

NASA Astrophysics Data System (ADS)

Maiorov, B. S.; Ignat'ev, N. I.; Moroz, V. I.; Zasova, L. V.; Moshkin, B. E.; Khatuntsev, I. V.; Ekonomov, A. P.

2005-07-01

The processes of the solar radiation extinction in deep layers of the Venus atmosphere in a wavelength range from 0.44 to 0.66 µm have been considered. The spectra of the solar radiation scattered in the atmosphere of Venus at various altitudes above the planetary surface measured by the Venera-11 entry probe in December 1978 are used as observational data. The problem of the data analysis is solved by selecting an atmospheric model; the discrete-ordinate method is applied in calculations. For the altitude interval from 2 10 km to 36 km, the altitude and spectral dependencies of the volume coefficient of true absorption have been obtained. At altitudes of 3 19 km, the spectral dependence is close to the wavelength dependence of the absorption cross section of S3 molecules, whence it follows that the mixing ratio of this sulfur allotrope increases with altitude from 0.03 to 0.1 ppbv.

Analytical Investigation of a Flicker-Type Roll Control for a Mach Number 6 Missile with Aerodynamic Controls Over An Altitude Range of 82,000 to 282,000 feet

NASA Technical Reports Server (NTRS)

Lundstrom, Reginald R.; Whitman, Ruth I.

1959-01-01

An analytical investigation has been carried out to determine the responses of a flicker-type roll control incorporated in a missile which traverses a range of Mach number of 6.3 at an altitude of 82,000 feet to 5.26 at an altitude of 282,000 feet. The missile has 80 deg delta wings in a cruciform arrangement with aerodynamic controls attached to the fuselage near the wing trailing edge and indexed 450 to the wings. Most of the investigation was carried out on an analog computer. Results showed that roll stabilization that may be adequate for many cases can be obtained over the altitude range considered, providing that the rate factor can be changed with altitude. The response would be improved if the control deflection were made larger at the higher altitudes. lag times less than 0.04 second improve the response appreciably. Asymmetries that produce steady rolling moments can be very detrimental to the response in some cases. The wing damping made a negligible contribution to the response.

Using a Convection Model to Predict Altitudes of White Stork Migration Over Central Israel

NASA Astrophysics Data System (ADS)

Shamoun-Baranes, Judy; Liechti, Olivier; Yom-Tov, Yoram; Leshem, Yossi

Soaring migrants such as storks, pelicans and large birds of prey rely on thermal convection during migration. The convection model ALPTHERM was designed to predict the onset, strength, duration and depth of thermal convection for varying topographies for glider pilots, based on atmospheric conditions at midnight. We tested ALPTHERM predictions as configured for two topographies of central Israel, the Coastal Plains and the Judean and Samarian Mountains in order to predict altitudes of migrating white storks (Ciconia ciconia). Migrating flocks of white storks were tracked with a motorized glider, to measure maximum altitudes of migration during spring 2000. A significant positive correlation was found between the maximum daily altitudes of migration measured and the predicted upper boundary of thermal convection for the Coastal Plains and Samarian Mountains. Thirty-minute predictions for the Coastal Plains and Samarian Mountains correlated positively with measured maximum migration altitudes per thermal. ALPTHERM forecasts can be used to alter flight altitudes in both civil and especially military aviation and reduce the hazard of serious aircraft collisions with soaring migrants.

Carcass yields of two different strains of ducks raised in different altitude

NASA Astrophysics Data System (ADS)

Dillak, St. Y. F. G.; Mulyantini, N. G. A.; Sipahelut, G. M.; Lole, U. R.

2018-02-01

The objective of this research was to determine if there is a difference in performance and carcass yield between ducks of two different strains raised in different altitude. Ducks different strains (Muscovy vs Pekin ducks) and they raised either in high or low altitude (high altitude which was between 500 and 1000m vs low altitude which was below 500m). All ducks were given one of two different diet s and provided water ad libitum. The diets were: 1) commercial diet, and 2) local diet. There were three replicate per treatment and there were 5 ducks per replication. Ducks from each strain were standardized to a similar weight. The results show that Pekin ducks carcass performance was significantly better than Muscovy ducks. Ducks given diet 2 had significantly (P<0.001) lower carcass percentage than those given diet 1. Pekin ducks had greater genetic potential for carcass performance in high altitude environment. However, abdominal fat percentage in Pekin ducks is significantly (P<0.01) higher than abdominal fat percentage in Muscovy ducks.

Range of Density Variability from Surface To 120 km Altitude

NASA Technical Reports Server (NTRS)

Smith, Orvel E.; Chenoweth, Halsey B.

1961-01-01

A re-entry space vehicle development program, such as Project Apollo, requires a knowledge of the variability of atmospheric density from the surface of the earth to re-entry altitude (120 km). This report summarizes the data on density given in the most recent literature on the subject. The range of atmospheric density with respect to the ARDC 1959 Model Atmosphere is determined and shown graphically. From the surface to 30 km altitude abundant information on density is available. From 30 to 90 km altitude the summarized reports of observations made at a limited number of stations have been used. Between 90 and 120 km altitude the density is somewhat speculative, there being but few measurements available. Therefore, the qualitative values for the variability of density above 30 km must be considered tentative. Variations of atmospheric density by latitude and seasons made it necessary to develop a family of curves rather than a single profile. Three curves are presented to show the range of density deviation versus altitudes with respect to the ARDC 1959 Model Atmosphere. Each curve is used for a specific latitude range and season.

Airborne Measurements of CO2 Column Absorption and Range Using a Pulsed Direct-Detection Integrated Path Differential Absorption Lidar

NASA Technical Reports Server (NTRS)

Abshire, James B.; Riris, Haris; Weaver, Clark J.; Mao, Jianping; Allan, Graham R.; Hasselbrack, William E.; Browell, Edward V.

2013-01-01

We report on airborne CO2 column absorption measurements made in 2009 with a pulsed direct-detection lidar operating at 1572.33 nm and utilizing the integrated path differential absorption technique. We demonstrated these at different altitudes from an aircraft in July and August in flights over four locations in the central and eastern United States. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. The lidar measurement statistics were also calculated for each flight as a function of altitude. The optical depth varied nearly linearly with altitude, consistent with calculations based on atmospheric models. The scatter in the optical depth measurements varied with aircraft altitude as expected, and the median measurement precisions for the column varied from 0.9 to 1.2 ppm. The altitude range with the lowest scatter was 810 km, and the majority of measurements for the column within it had precisions between 0.2 and 0.9 ppm.

Bathymetry of Walker Lake, West-Central Nevada

USGS Publications Warehouse

Lopes, Thomas J.; Smith, J. LaRue

2007-01-01

Walker Lake lies within a topographically closed basin in west-central Nevada and is the terminus of the Walker River. Much of the streamflow in the Walker River is diverted for irrigation, which has contributed to a decline in lake-surface altitude of about 150 feet and an increase in dissolved solids from 2,500 to 16,000 milligrams per liter in Walker Lake since 1882. The increase in salinity threatens the fresh-water ecosystem and survival of the Lahontan cutthroat trout, a species listed as threatened under the Endangered Species Act. Accurately determining the bathymetry and relations between lake-surface altitude, surface area, and storage volume are part of a study to improve the water budget for Walker Lake. This report describes the updated bathymetry of Walker Lake, a comparison of results from this study and a study by Rush in 1970, and an estimate of the 1882 lake-surface altitude. Bathymetry was measured using a single-beam echosounder coupled to a differentially-corrected global positioning system. Lake depth was subtracted from the lake-surface altitude to calculate the altitude of the lake bottom. A Lidar (light detection and ranging) survey and high resolution aerial imagery were used to create digital elevation models around Walker Lake. The altitude of the lake bottom and digital elevation models were merged together to create a single map showing land-surface altitude contours delineating areas that are currently or that were submerged by Walker Lake. Surface area and storage volume for lake-surface altitudes of 3,851.5-4,120 feet were calculated with 3-D surface-analysis software. Walker Lake is oval shaped with a north-south trending long axis. On June 28, 2005, the lake-surface altitude was 3,935.6 feet, maximum depth was 86.3 feet, and the surface area was 32,190 acres. The minimum altitude of the lake bottom from discrete point depths is 3,849.3 feet near the center of Walker Lake. The lake bottom is remarkably smooth except for mounds near the shore and river mouth that could be boulders, tree stumps, logs, or other submerged objects. The echosounder detected what appeared to be mounds in the deepest parts of Walker Lake, miles from the shore and river mouth. However, side-scan sonar and divers did not confirm the presence of mounds. Anomalies occur in two northwest trending groups in northern and southern Walker Lake. It is hypothesized that some anomalies indicate spring discharge along faults based on tufa-like rocks that were observed and the northwest trend parallel to and in proximity of mapped faults. Also, evaporation measured from Walker Lake is about 50 percent more than the previous estimate, indicating more water is flowing into the lake from sources other than the Walker River. Additional studies need to be done to determine what the anomalies are and whether they are related to the hydrology of Walker Lake. Most differences in surface area and storage volume between this study and a study by Rush in 1970 were less than 1 percent. The largest differences occur at lake-surface altitudes less than 3,916 feet. In general, relations between lake-surface altitude, surface area, and storage volume from Rush's study and this study are nearly identical throughout most of the range in lake-surface altitude. The lake-surface altitude in 1882 was estimated to be between 4,080 feet and 4,086 feet with a probable altitude of 4,082 feet. This estimate compares well with two previous estimates of 4,083 feet and 4,086 feet. Researchers believe the historic highstand of Walker Lake occurred in 1868 and estimated the highstand was between 4,089 feet and 4,108 feet. By 1882, Mason Valley was predominantly agricultural. The 7-26 feet decline in lake-surface altitude between 1868 and 1882 could partially be due to irrigation diversions during this time.

High altitude cognitive performance and COPD interaction

PubMed Central

Kourtidou-Papadeli, C; Papadelis, C; Koutsonikolas, D; Boutzioukas, S; Styliadis, C; Guiba-Tziampiri, O

2008-01-01

Introduction: Thousands of people work and perform everyday in high altitude environment, either as pilots, or shift workers, or mountaineers. The problem is that most of the accidents in this environment have been attributed to human error. The objective of this study was to assess complex cognitive performance as it interacts with respiratory insufficiency at altitudes of 8000 feet and identify the potential effect of hypoxia on safe performance. Methods: Twenty subjects participated in the study, divided in two groups: Group I with mild asymptomatic chronic obstructive pulmonary disease (COPD), and Group II with normal respiratory function. Altitude was simulated at 8000 ft. using gas mixtures. Results: Individuals with mild COPD experienced notable hypoxemia with significant performance decrements and increased number of errors at cabin altitude, compared to normal subjects, whereas their blood pressure significantly increased. PMID:19048098

The electric field structure of auroral arcs as determined from barium plasma injection experiments

NASA Technical Reports Server (NTRS)

Wescott, E. M.

1981-01-01

Barium plasma injection experiments have revealed a number of features of electric fields in and near auroral forms extending from a few hundred to many thousands of km in altitude. There is evidence for V-type potential structures over some auroras, but not in others. For some auroral arcs, large E fields are found at ionospheric altitudes outside the arc but the E field inside the arc is near zero. In a few other auroras, most recently one investigated in an experiment conducted from Poker Flat on March 22, 1980, large, rapidly fluctuating E fields were detected by barium plasma near 600 km altitude. These E fields suggest that the motion of auroral rays can be an effect of low-altitude electric fields, or that V-type potential structures may be found at low altitudes.

High-Altitude Flight Cooling Investigation of a Radial Air-Cooled Engine

NASA Technical Reports Server (NTRS)

Manganiello, Eugene J; Valerino, Michael F; Bell, E Barton

1947-01-01

An investigation of the cooling of an 18-cylinder, twin-row, radial, air-cooled engine in a high-performance pursuit airplane has been conducted for variable engine and flight conditions at altitudes ranging from 5000 to 35,000 feet in order to provide a basis for predicting high-altitude cooling performance from sea-level or low altitude experimental results. The engine cooling data obtained were analyzed by the usual NACA cooling-correlation method wherein cylinder-head and cylinder-barrel temperatures are related to the pertinent engine and cooling-air variables. A theoretical analysis was made of the effect on engine cooling of the change of density of the cooling air across the engine (the compressibility effect), which becomes of increasing importance as altitude is increased. Good agreement was obtained between the results of the theoretical analysis and the experimental data.

Comparative atmosphere structure experiment

NASA Technical Reports Server (NTRS)

Sommer, S.

1974-01-01

Atmospheric structure of outer planets as determined by pressure, temperature, and accelerometers is reviewed and results obtained from the PAET earth entry are given. In order to describe atmospheric structure, entry is divided into two regimes, high and low speed. Acceleration is then measured: from these measurements density is determined as a function of time. The equations of motion are integrated to determine velocity, flight path angle, and altitude as a function of time. Density is then determined as a function of altitude from the previous determinations of density and altitude as a function of time. Hydrostatic equilibrium was assumed to determine pressure as a function of altitude. Finally the equation of space applied to determine temperature as a function of altitude, if the mean molecular weight is known. The mean molecular weight is obtained independently from either the low speed experiment or from the composition experiments.

[Variations of soil labile organic carbon along an altitude gradient in Wuyi Mountain].

PubMed

Xu, Xia; Chen, Yue-Qin; Wang, Jia-She; Fang, Yan-Hong; Quan, Wei; Ruan, Hong-Hua; Xu, Zi-Kun

2008-03-01

By using sequential fumigation-incubation method, this paper determined the soil labile organic carbon (LOC) content under evergreen broadleaf forest, coniferous forest, sub-alpine dwarf forest, and alpine meadow along an altitude gradient in Wuyi Mountain National Nature Reserve in Fujian Province of China, with its relations to soil microbial biomass carbon (MBC), total organic carbon (TOC), total nitrogen (TN), and fine root biomass (FRB) analyzed. The results showed that soil LOC occupied 3.40%-7.46% of soil TOC, and soil MBC occupied 26.87%-80.38% of the LOC. The LOC under different forest stands increased significantly with altitude, and decreased with soil depth. Soil LOC had very significant correlations with soil MBC, TOC, TN and FRB, and its content was obviously higher at higher altitudes than at lower altitudes.

Patients with obstructive sleep apnea syndrome benefit from acetazolamide during an altitude sojourn: a randomized, placebo-controlled, double-blind trial.

PubMed

Nussbaumer-Ochsner, Yvonne; Latshang, Tsogyal D; Ulrich, Silvia; Kohler, Malcolm; Thurnheer, Robert; Bloch, Konrad E

2012-01-01

Many patients with obstructive sleep apnea syndrome (OSA) are unable or unwilling to use continuous positive airway pressure (CPAP) therapy when traveling to the mountains for work or recreation even though they risk pronounced hypoxemia and exacerbation of sleep apnea. Because the treatment of OSA at altitude has not been established, we tested the hypothesis that acetazolamide improves hypoxemia, sleep, and breathing disturbances in otherwise untreated patients with OSA at altitude. Forty-five patients with OSA on long-term CPAP, median age 64 years, living at < 600 m underwent a placebo-controlled, double-blind, crossover trial randomized for the sequence of drug and altitude exposure (490 m, 1,860 m, and 2,590 m). Patients spent two 3-day periods at altitude and a 2-week wash-out period at < 600 m. At altitude, patients discontinued CPAP and received acetazolamide 2 × 250 mg daily or placebo. Polysomnography, vigilance, and symptoms were evaluated. At 490 m, off CPAP, median nocturnal oxygen saturation was 93%, and the apnea/hypopnea index was 51.2/h. On placebo at 1,860 m and 2,590 m, the corresponding values were 89% and 85% and 63.6/h and 86.2/h, respectively (P < .01 vs 490 m, both instances). On acetazolamide at 1,860 m and 2,590 m, oxygen saturation was higher (91% and 88%) and apnea/hypopnea indices were lower (48.0/h and 61.4/h) than on placebo (P < .01 all instances). Acetazolamide reduced nocturnal transcutaneous Pco(2), improved sleep efficiency and subjective insomnia, and prevented excessive BP elevations at altitude. In patients with OSA discontinuing CPAP during an altitude sojourn, acetazolamide improves oxygenation, breathing disturbances, and sleep quality by stimulating ventilation. Therefore, patients with OSA may benefit from acetazolamide at altitude if CPAP therapy is not feasible. ClinicalTrials.gov; No.: NCT00714740; URL: www.clinicaltrials.gov.

Augmented uterine artery blood flow and oxygen delivery protect Andeans from altitude-associated reductions in fetal growth

PubMed Central

Julian, Colleen Glyde; Wilson, Megan J.; Lopez, Miriam; Yamashiro, Henry; Tellez, Wilma; Rodriguez, Armando; Bigham, Abigail W.; Shriver, Mark D.; Rodriguez, Carmelo; Vargas, Enrique; Moore, Lorna G.

2009-01-01

The effect of high altitude on reducing birth weight is markedly less in populations of high- (e.g., Andeans) relative to low-altitude origin (e.g., Europeans). Uterine artery (UA) blood flow is greater during pregnancy in Andeans than Europeans at high altitude; however, it is not clear whether such blood flow differences play a causal role in ancestry-associated variations in fetal growth. We tested the hypothesis that greater UA blood flow contributes to the protection of fetal growth afforded by Andean ancestry by comparing UA blood flow and fetal growth throughout pregnancy in 137 Andean or European residents of low (400 m; European n = 28, Andean n = 23) or high (3,100–4,100 m; European n = 51, Andean n = 35) altitude in Bolivia. Blood flow and fetal biometry were assessed by Doppler ultrasound, and maternal ancestry was confirmed, using a panel of 100 ancestry-informative genetic markers (AIMs). At low altitude, there were no ancestry-related differences in the pregnancy-associated rise in UA blood flow, fetal biometry, or birth weight. At high altitude, Andean infants weighed 253 g more than European infants after controlling for gestational age and other known influences. UA blood flow and O2 delivery were twofold greater at 20 wk in Andean than European women at high altitude, and were paralleled by greater fetal size. Moreover, variation in the proportion of Indigenous American ancestry among individual women was positively associated with UA diameter, blood flow, O2 delivery, and fetal head circumference. We concluded that greater UA blood flow protects against hypoxia-associated reductions in fetal growth, consistent with the hypothesis that genetic factors enabled Andeans to achieve a greater pregnancy-associated rise in UA blood flow and O2 delivery than European women at high altitude. PMID:19244584

Altitude and endurance training.

PubMed

Rusko, Heikki K; Tikkanen, Heikki O; Peltonen, Juha E

2004-10-01

The benefits of living and training at altitude (HiHi) for an improved altitude performance of athletes are clear, but controlled studies for an improved sea-level performance are controversial. The reasons for not having a positive effect of HiHi include: (1) the acclimatization effect may have been insufficient for elite athletes to stimulate an increase in red cell mass/haemoglobin mass because of too low an altitude (< 2000-2200 m) and/or too short an altitude training period (<3-4 weeks); (2) the training effect at altitude may have been compromised due to insufficient training stimuli for enhancing the function of the neuromuscular and cardiovascular systems; and (3) enhanced stress with possible overtraining symptoms and an increased frequency of infections. Moreover, the effects of hypoxia in the brain may influence both training intensity and physiological responses during training at altitude. Thus, interrupting hypoxic exposure by training in normoxia may be a key factor in avoiding or minimizing the noxious effects that are known to occur in chronic hypoxia. When comparing HiHi and HiLo (living high and training low), it is obvious that both can induce a positive acclimatization effect and increase the oxygen transport capacity of blood, at least in 'responders', if certain prerequisites are met. The minimum dose to attain a haematological acclimatization effect is > 12 h a day for at least 3 weeks at an altitude or simulated altitude of 2100-2500 m. Exposure to hypoxia appears to have some positive transfer effects on subsequent training in normoxia during and after HiLo. The increased oxygen transport capacity of blood allows training at higher intensity during and after HiLo in subsequent normoxia, thereby increasing the potential to improve some neuromuscular and cardiovascular determinants of endurance performance. The effects of hypoxic training and intermittent short-term severe hypoxia at rest are not yet clear and they require further study.

Preliminary study on alterations of altitude road traffic in China from 2006 to 2013

PubMed Central

Zhao, Hui; Yin, Zhiyong; Xiang, Hongyi; Liao, Zhikang; Wang, Zhengguo

2017-01-01

Introduction Road traffic can play an important role in strengthening regional economic activities, especially at high altitude, and it is necessary to know important traffic-related information. Although previous studies reported on road traffic in China, there has been little research on high-altitude road traffic to date. Method The annual official census of road traffic safety from 2006 to 2013 was used to obtain data on the general population, registered drivers, registered vehicles, newly built roads, road traffic accidents (RTAs), mortality rate per 100 000 populations and per 10 000 vehicles in high-altitude provinces, including Tibet, Qinghai, Xinjiang, Gansu, Yunnan, Sichuan, and Chongqing. These provincial data were reviewed retrospectively, with the national data as the reference. Statistical analysis (i.e., t test) was used to compare the estimated average annual change rate of population, number of registered drivers, registered vehicles, and newly built roads in high-altitude provinces with the national rates. Results Compared with the national data, there are significantly higher annual rates of population growth in Tibet and Xinjiang, registered drivers in Gansu, registered vehicles in Gansu, Sichuan, and Chongqing, and newly built roads in Tibet and Qinghai. Among the investigated provinces, Tibet, Qinghai, and Yunnan had a higher proportion of the roads with the high class. RTAs and RTA-induced casualties in the high-altitude provinces indicated a decreasing trend. The mortality rate per 10 000 vehicles and per 100 000 populations showed a decreasing trend, while the RTA-related mortality rate in Tibet, Qinghai, Xinjiang and Gansu remained high. Conclusions Major changes for road traffic in high-altitude provinces have occurred over the past decade; however, the RTA-related mortality rate in high-altitude provinces has remained high. This study furthers understanding about road traffic safety in China; further studies on road traffic safety at high altitude should be performed. PMID:28187203

Maternal oxygen delivery is not related to altitude- and ancestry-associated differences in human fetal growth

PubMed Central

Zamudio, Stacy; Postigo, Lucrecia; Illsley, Nicholas P; Rodriguez, Carmelo; Heredia, Gladys; Brimacombe, Michael; Echalar, Lourdes; Torricos, Tatiana; Tellez, Wilma; Maldonado, Ivan; Balanza, Elfride; Alvarez, Tatiana; Ameller, Julio; Vargas, Enrique

2007-01-01

Fetal growth is reduced at high altitude, but the decrease is less among long-resident populations. We hypothesized that greater maternal uteroplacental O2 delivery would explain increased fetal growth in Andean natives versus European migrants to high altitude. O2 delivery was measured with ultrasound, Doppler and haematological techniques. Participants (n= 180) were pregnant women of self-professed European or Andean ancestry living at 3600 m or 400 m in Bolivia. Ancestry was quantified using ancestry-informative single nucleotide polymorphims. The altitude-associated decrement in birth weight was 418 g in European versus 236 g in Andean women (P < 0.005). Altitude was associated with decreased uterine artery diameter, volumetric blood flow and O2 delivery regardless of ancestry. But the hypothesis was rejected as O2 delivery was similar between ancestry groups at their respective altitudes of residence. Instead, Andean neonates were larger and heavier per unit of O2 delivery, regardless of altitude (P < 0.001). European admixture among Andeans was negatively correlated with birth weight at both altitudes (P < 0.01), but admixture was not related to any of the O2 transport variables. Genetically mediated differences in maternal O2 delivery are thus unlikely to explain the Andean advantage in fetal growth. Of the other independent variables, only placental weight and gestational age explained significant variation in birth weight. Thus greater placental efficiency in O2 and nutrient transport, and/or greater fetal efficiency in substrate utilization may contribute to ancestry- and altitude-related differences in fetal growth. Uterine artery O2 delivery in these pregnancies was 99 ± 3 ml min−1, ∼5-fold greater than near-term fetal O2 consumption. Deficits in maternal O2 transport in third trimester normal pregnancy are unlikely to be causally associated with variation in fetal growth. PMID:17510190

Spectral and Vertical Distribution Properties of Titan's Particulates from Thermal-IR CIRS Data: Physical Implications

NASA Technical Reports Server (NTRS)

Anderson, Carrie M.; Samuelson, Robert; Vinatier, Sandrine

2011-01-01

Analyses of far-IR spectra between 20 and 560/cm (500 and 18 micron) recorded by the Cassini Composite Infrared Spectrometer (CIRS) yield the spectral dependence and the vertical distribution of Titan's photochemical aerosol and stratospheric ice clouds. Below the stratopause (approx. 300 km) the aerosol appears to be incompletely mixed for the following reasons: 1) the altitude dependence of the aerosol mass absorption coefficient is larger at higher altitudes than at lower altitudes, 2} the aerosol scale height varies with altitude, which implies some kind of layering effect, and 3) the aerosol abundance varies with latitude. The spectral shape of the aerosol opacity appears to be independent in altitude and latitude below the stratopause, even though inhomogeneities in the abundance appear to be prevalent throughout this altitude region. This implies that aerosol chemistry is restricted to altitude regions above the stratopause, where pressures are less than approx 0.1 mbar. The aerosol exhibits an extremely broad emisSion feature with a spectral peak at 140/cm (71 micron), which is not evident in laboratory simulated Titan aerosols (tholin) that are created at pressures greater than 0.1 mbar. A strong broad emission feature centered roughly around 160 cm-1 corresponds very closely to those found in nitrile ice spectra. This feature is pervasive throughout the region from high northern to high southern latitudes. The inference of nitrile ices is consistent with the highly restricted altitude ranges over which these features are observed, and appear to be dominated by HCN and HC3N. At low and moderate latitudes these clouds are observed to be located between 60 and 100 km, whereas at high northern latitudes during northern winter these clouds are observed at altitudes between 150 and 165 km. The ubiquitous nature of these nitrile ice clouds is inconsistent with a simple meridional circulation concept, suggesting that the true dynamical situation is more complex.

Aero-thermo-dynamic analysis of the Spaceliner-7.1 vehicle in high altitude flight

NASA Astrophysics Data System (ADS)

Zuppardi, Gennaro; Morsa, Luigi; Sippel, Martin; Schwanekamp, Tobias

2014-12-01

SpaceLiner, designed by DLR, is a visionary, extremely fast passenger transportation concept. It consists of two stages: a winged booster, a vehicle. After separation of the two stages, the booster makes a controlled re-entry and returns to the launch site. According to the current project, version 7-1 of SpaceLiner (SpaceLiner-7.1), the vehicle should be brought at an altitude of 75 km and then released, undertaking the descent path. In the perspective that the vehicle of SpaceLiner-7.1 could be brought to altitudes higher than 75 km, e.g. 100 km or above and also for a speculative purpose, in this paper the aerodynamic parameters of the SpaceLiner-7.1 vehicle are calculated in the whole transition regime, from continuum low density to free molecular flows. Computer simulations have been carried out by three codes: two DSMC codes, DS3V in the altitude interval 100-250 km for the evaluation of the global aerodynamic coefficients and DS2V at the altitude of 60 km for the evaluation of the heat flux and pressure distributions along the vehicle nose, and the DLR HOTSOSE code for the evaluation of the global aerodynamic coefficients in continuum, hypersonic flow at the altitude of 44.6 km. The effectiveness of the flaps with deflection angle of -35 deg. was evaluated in the above mentioned altitude interval. The vehicle showed longitudinal stability in the whole altitude interval even with no flap. The global bridging formulae verified to be proper for the evaluation of the aerodynamic coefficients in the altitude interval 80-100 km where the computations cannot be fulfilled either by CFD, because of the failure of the classical equations computing the transport coefficients, or by DSMC because of the requirement of very high computer resources both in terms of the core storage (a high number of simulated molecules is needed) and to the very long processing time.

Quasi-Static Alfv{é}n Dynamics and Scale-Dependent Energy Deposition in Magnetosphere-Ionosphere Coupling

NASA Astrophysics Data System (ADS)

Lotko, W.; Lysak, R. L.; Streltsov, A. V.

2002-12-01

Alfv{é}n wave dynamics become quasi-static in the ionosphere and low-altitude magnetosphere in the ULF regime below 10 mHz and at altitudes less than a few RE when the following two conditions are met: ω L RE << vA (l) and ω l << 1 / μ 0 Σ P. L is the dipole shell parameter, ω is the wave frequency in radians, l represents field-aligned distance above the ionosphere, vA (l) is the local Alfv{é}n speed, and Σ P is the ionospheric Pedersen conductance. In this limit, reactive power stored in Alfv{é}nic fluctuations at high altitude flows quasi-statically into ionospheric Joule heating and low-altitude collisionless dissipation. The combined dissipative effects are described by the electrostatic model of Chiu-Cornwall-Lyons [1980] which captures the transverse wavelength dependence of low-altitude Alfv{é}nic energy deposition. The analysis and results described here 1) correspond to the low-altitude, low-frequency limit of theories for the interaction of an Alfv{é}n wave with the ionosphere [Knudsen et al., 1992], including effects of a low-altitude collisionless dissipation layer [Vogt and Haerendel, 1998], and field line eigenmodes with allowance for finite ionospheric conductivity and realistic parallel inhomogeneity [Allan and Knox, 1979]; 2) reconcile the interpretation of inverted-V precipitation regions as electrostatic potential structures with electromagnetic energy deposition via Alfv{é}n waves at frequencies below 10 mHz; 3) provide criteria for the validity of the Knight current-voltage relation in the ULF regime and its use in global MHD simulations; 4) relate low-altitude satellite measurements of both ``static'' and ULF electric and magnetic fields directly to the ionospheric Pedersen conductivity; and 5) offer a resolution to debates about high-altitude closure of auroral potential structures as O-, U-, or S-potential forms.

Predicted optical performance of the high-altitude balloon experiment (HABE) telescope in an adverse thermal environment

NASA Astrophysics Data System (ADS)

Akau, Ronald L.; Givler, Richard C.; Eastman, Daniel R.

1994-07-01

The High-Altitude Balloon Experiment telescope was designed to operate at an ambient temperature of -55 degree(s)C and an altitude of 26 km, using a precooled primary mirror. Although at this altitude the air density is only 1.4 percent of the value at sea level, the temperature gradients within the telescope are high enough to deform the optical wavefront. This problem is considerably lessened by precooling the primary mirror to -35 degree(s)C. This paper describes the application of several codes to determine the range of wavefront deformation during a mission.

Effects on the orbital debris environment due to solar activity

NASA Technical Reports Server (NTRS)

Kessler, Donald J.; Anz-Meador, Phillip D.

1990-01-01

The rate that earth-orbiting debris is removed from the environment is dependent on a number of factors which include orbital altitude and solar activity. It is generally believed that at lower altitudes and especially during periods of high solar activity, debris generated in the past will be eliminated from the environment. While some debris is eliminated, most is replaced by old debris from higher altitudes or new debris from recent launches. Some low altitude debris, which would reenter if the debris were in circular orbits, does not reenter because the debris is in higher-energy elliptical orbits.

RECOZ data reduction and analysis: Programs and procedures

NASA Technical Reports Server (NTRS)

Reed, E. I.

1984-01-01

The RECOZ data reduction programs transform data from the RECOZ photometer to ozone number density and overburden as a function of altitude. Required auxiliary data are the altitude profile versus time and for appropriate corrections to the ozone cross sections and scattering effects, air pressure and temperature profiles. Air temperature and density profiles may also be used to transform the ozone density versus geometric altitude to other units, such as to ozone partial pressure or mixing ratio versus pressure altitude. There are seven programs used to accomplish this: RADAR, LISTRAD, RAW OZONE, EDIT OZONE, MERGE, SMOOTH, and PROFILE.

Evolved changes in the intracellular distribution and physiology of muscle mitochondria in high-altitude native deer mice.

PubMed

Mahalingam, Sajeni; McClelland, Grant B; Scott, Graham R

2017-07-15

Mitochondrial function changes over time at high altitudes, but the potential benefits of these changes for hypoxia resistance remains unclear. We used high-altitude-adapted populations of deer mice, which exhibit enhanced aerobic performance in hypoxia, to examine whether changes in mitochondrial physiology or intracellular distribution in the muscle contribute to hypoxia resistance. Permeabilized muscle fibres from the gastrocnemius muscle had higher respiratory capacities in high-altitude mice than in low-altitude mice. Highlanders also had higher mitochondrial volume densities, due entirely to an enriched abundance of subsarcolemmal mitochondria, such that more mitochondria were situated near the cell membrane and adjacent to capillaries. There were several effects of hypoxia acclimation on mitochondrial function, some of which were population specific, but they differed from the evolved changes in high-altitude natives, which probably provide a better indication of adaptive traits that improve performance and hypoxia resistance at high altitudes. High-altitude natives that have evolved to live in hypoxic environments provide a compelling system to understand how animals can overcome impairments in oxygen availability. We examined whether these include changes in mitochondrial physiology or intracellular distribution that contribute to hypoxia resistance in high-altitude deer mice (Peromyscus maniculatus). Mice from populations native to high and low altitudes were born and raised in captivity, and as adults were acclimated to normoxia or hypobaric hypoxia (equivalent to 4300 m elevation). We found that highlanders had higher respiratory capacities in the gastrocnemius (but not soleus) muscle than lowlanders (assessed using permeabilized fibres with single or multiple inputs to the electron transport system), due in large part to higher mitochondrial volume densities in the gastrocnemius. The latter was attributed to an increased abundance of subsarcolemmal (but not intermyofibrillar) mitochondria, such that more mitochondria were situated near the cell membrane and adjacent to capillaries. Hypoxia acclimation had no significant effect on these population differences, but it did increase mitochondrial cristae surface densities of mitochondria in both populations. Hypoxia acclimation also altered the physiology of isolated mitochondria by affecting respiratory capacities and cytochrome c oxidase activities in population-specific manners. Chronic hypoxia decreased the release of reactive oxygen species by isolated mitochondria in both populations. There were subtle differences in O 2 kinetics between populations, with highlanders exhibiting increased mitochondrial O 2 affinity or catalytic efficiency in some conditions. Our results suggest that evolved changes in mitochondrial physiology in high-altitude natives are distinct from the effects of hypoxia acclimation, and probably provide a better indication of adaptive traits that improve performance and hypoxia resistance at high altitudes. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

Variation in airborne 134Cs, 137Cs, particulate 131I and 7Be maximum activities at high-altitude European locations after the arrival of Fukushima-labeled air masses.

PubMed

Masson, Olivier; Bieringer, Jacqueline; Brattich, Erika; Dalheimer, Axel; Estier, Sybille; Penev, Ilia; Ringer, Wolfgang; Schlosser, Clemens; Steinkopff, Thomas; Steinmann, Philipp; Tositti, Laura; Van Beek, Pieter; Vismes-Ott, Anne de

2016-10-01

The Fukushima-labeled air mass arrival, and later the cesium-134 ( 134 Cs), cesium-137 ( 137 Cs) and particulate iodine-131 (hereafter noted 131 I p ) maximum levels were registered in Europe at different dates depending on the location. Most of those data were obtained at low-altitude sampling areas. Here, we compare the airborne levels registered at different high-altitude European locations (from 850 m to about 3500 m). The integrated 137 Cs activity concentration was not uniform with regard to the altitude even after a long travel time/distance from Japan. Moreover, the relation of integrated 137 Cs vs. altitude showed a linear decrease up to an altitude of about 3000 m. A similar trend was noticed for 131 I p (particulate fraction) while it increased above 3000 m. Comparison with 7 Be activity concentration showed that, as far as the high altitude location is concerned, the 137 Cs and 134 Cs maximum concentrations corresponded to the 7 Be maximum, suggesting downdraft movements from high tropospheric or stratospheric layers to be responsible for 137,134 Cs increase and peak values. This was also confirmed by high potential vorticity and low relative humidity registered during the peak values. Copyright © 2016 Elsevier Ltd. All rights reserved.

Disturbances in Maternal Steroidogenesis and Appearance of Intrauterine Growth Retardation at High-Altitude Environments Are Established from Early Pregnancy. Effects of Treatment with Antioxidant Vitamins

PubMed Central

Parraguez, Victor H.; Mamani, Sandra; Cofré, Eileen; Castellaro, Giorgio; Urquieta, Bessie; De los Reyes, Mónica; Astiz, Susana; Gonzalez-Bulnes, Antonio

2015-01-01

Pregnancies at high-altitudes are influenced by hypoxia and oxidative stress and frequently affected by IUGR. However, a common thought is that early pregnant women visiting altitude have no major complications for gestation development, since IUGR is developed during the second half of pregnancy. Thus, using a well-characterized sheep-model, we aimed to determine whether long- and/or short-term exposure to high-altitude may affect maternal steroidogenesis and therefore embryo-fetal growth from conception. The second aim was to differentiate the relative role of hypoxia and oxidative stress by assessing the effects of supplementation with antioxidant agents during this early-pregnancy stage, which were previously found to be useful to prevent IUGR. The results indicate that both long- and short-term exposure to high-altitude causes disturbances in maternal ovarian steroidogenesis and negatively affects embryo-fetal growth already during the very early stages of gestation, with the consequences being even worsened in newcomers to high-altitude. The supply of antioxidant during this period only showed discrete effects for preventing IUGR. In conclusion, the present study gives a warning for clinicians about the risks for early-pregnant women when visiting high-altitude regions and suggests the need for further studies on the effects of the length of exposure and on the interaction of the exposure with the pregnancy stage. PMID:26560325

Helicopter pilot scan techniques during low-altitude high-speed flight.

PubMed

Kirby, Christopher E; Kennedy, Quinn; Yang, Ji Hyun

2014-07-01

This study examined pilots' visual scan patterns during a simulated high-speed, low-level flight and how their scan rates related to flight performance. As helicopters become faster and more agile, pilots are expected to navigate at low altitudes while traveling at high speeds. A pilot's ability to interpret information from a combination of visual sources determines not only mission success, but also aircraft and crew survival. In a fixed-base helicopter simulator modeled after the U.S. Navy's MH-60S, 17 active-duty Navy helicopter pilots with varying total flight times flew and navigated through a simulated southern Californian desert course. Pilots' scan rate and fixation locations were monitored using an eye-tracking system while they flew through the course. Flight parameters, including altitude, were recorded using the simulator's recording system. Experienced pilots with more than 1000 total flight hours better maintained a constant altitude (mean altitude deviation = 48.52 ft, SD = 31.78) than less experienced pilots (mean altitude deviation = 73.03 ft, SD = 10.61) and differed in some aspects of their visual scans. They spent more time looking at the instrument display and less time looking out the window (OTW) than less experienced pilots. Looking OTW was associated with less consistency in maintaining altitude. Results may aid training effectiveness specific to helicopter aviation, particularly in high-speed low-level flight conditions.

Compositional changes in bee and wasp communities along Neotropical mountain altitudinal gradient.

PubMed

Perillo, Lucas Neves; Neves, Frederico de Siqueira; Antonini, Yasmine; Martins, Rogério Parentoni

2017-01-01

Climate conditions tend to differ along an altitudinal gradient, resulting in some species groups' patterns of lower species richness with increasing altitude. While this pattern is well understood for tropical mountains, studies investigating possible determinants of variation in beta-diversity at its different altitudes are scarce. We sampled bee and wasp communities (Hymenoptera: Aculeata) along an altitudinal gradient (1,000-2,000 m.a.s.l.) in a tropical mountainous region of Brazil. Trap nests and Moericke traps were established at six sampling points, with 200 m difference in altitude between each point. We obtained average climate data (1970-2000) from Worldclim v2 for altitudes at each sampling site. Nest traps captured 17 bee and wasp species from six families, and Moericke traps captured 124 morphospecies from 13 families. We found a negative correlation between altitude and species richness and abundance. Temperature, precipitation, water vapor pressure, and wind speed influenced species richness and abundance, and were correlated with altitude. β-diversity was primarily determined by species turnover as opposed to nestedness, and Aculeate community similarity was higher for more similar altitudinal ranges. Moericke traps seem to be more efficient for altitudinal surveys compared to nest traps. We found high occurrence of singleton and doubleton species at all altitudes, highlighting the need for long-term studies to efficiently assess hymenopteran diversity in these environments.

The effects of different rates of ascent on the incidence of altitude decompression sickness

NASA Technical Reports Server (NTRS)

Kumar, K. V.; Waligora, James M.

1989-01-01

The effect of different rates of ascent on the incidence of altitude decompression sickness (DCS) was analyzed by a retrospective study on 14,123 man-flights involving direct ascent up to 38,000 ft altitude. The data were classified on the basis of altitude attained, denitrogenation at ground level, duration of stay at altitude, rest or exercise while at altitude, frequency of exercise at altitude, and ascent rates. This database was further divided on the basis of ascent rates into different groups from 1000 ft/min up to 53,000 ft/min. The database was analyzed using multiple correlation and regression methods, and the results of the analysis reveal that ascent rates influence the incidence of DCS in combination with the various factors mentioned above. Rate of ascent was not a significant predictor of DCS and showed a low, but significant multiple correlation (R=0.31) with the above factors. Further, the effects of rates below 2500 ft/min are significantly different from that of rates above 2500 ft/min on the incidence of symptoms (P=0.03) and forced descent (P=0.01). At rates above 2500 ft/min and up to 53,000 ft/min, the effects of ascent rates are not significantly different (P greater than 0.05) in the population examined while the effects of rates below 2500 ft/min are not clear.

Urinary leukotriene E(4) levels are not increased prior to high-altitude pulmonary edema.

PubMed

Bärtsch, P; Eichenberger, U; Ballmer, P E; Gibbs, J S; Schirlo, C; Oelz, O; Mayatepek, E

2000-05-01

To examine whether increased urinary cysteinyl-leukotriene E(4) (LTE(4)) excretion, which has been found to be elevated in patients presenting with high-altitude pulmonary edema (HAPE), precedes edema formation. Prospective studies in a total of 12 subjects with susceptibility to HAPE. In a chamber study, seven subjects susceptible to HAPE and five nonsusceptible control subjects were exposed for 24 h to an altitude of 450 m (control day), and exposed for 20 h to 4,000 m after slow decompression over 4 h. In a field study, prospective measurements at low and high altitude were performed in five subjects developing HAPE at 4,559 m. Mountaineers with a radiographically documented history of HAPE and control subjects who did not develop HAPE with identical high-altitude exposure. 24-h urine collections. In the hypobaric chamber, none of the subjects developed HAPE. The 24-h urinary LTE(4) did not differ between HAPE susceptible and control subjects, nor between hypoxia and normoxic control day. In the field study, urinary LTE(4) was not increased in subjects with HAPE compared to values obtained prior to HAPE at high altitude and during 2 control days at low altitude. These data do not provide evidence that cysteinyl-leukotriene-mediated inflammatory response is associated with HAPE susceptibility or the development of HAPE within the context of our studies.

75 FR 6319 - Proposed Amendment of Low Altitude Area Navigation Route T-254; Houston, TX

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-09

... Amendment of Low Altitude Area Navigation Route T-254; Houston, TX AGENCY: Federal Aviation Administration... altitude Area Navigation (RNAV) route T-254 in the Houston, TX, terminal area by eliminating the segment..., TX, VORTAC. This action would eliminate a portion of T-254 that is no longer needed; thus, enhance...

75 FR 15632 - Proposed Amendment to and Establishment of Restricted Areas and Other Special Use Airspace...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-30

... restricted area is inadequate for training at medium to high altitudes. The restricted areas R-2402B and R...- 2402, at 30,000 feet MSL, is considered adequate for medium to high altitude weapons employment tactics... lateral maneuvering airspace needed to practice medium to high altitude standoff weapon delivery profiles...

76 FR 11399 - Proposed Amendment to and Establishment of Restricted Areas, Warren Grove; NJ

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-02

... altitudes, along with increased lateral space in the high and medium altitude regimes. With its maximum... that the FAA take this action due to the increased need for aircrew training in high-altitude weapons... aspects of the proposal. Communications should identify both docket numbers (FAA Docket No. FAA-2011-0104...

The Use of Dexamethasone in Support of High-Altitude Ground Operations and Physical Performance: Review of the Literature

DTIC Science & Technology

2014-12-01

rates vary dramatically, the physiological effect of hypobaric high-altitude hypoxia ( HHH ) is ubiquitous.1,2 Symptoms of less severe cases of HHH ...nausea, headache, and peripheral edema.3-6 More severe cases of HHH may result in acute mountain sickness (AMS), high-altitude pulmonary edema

Active Learning in the Atmospheric Science Classroom and beyond through High-Altitude Ballooning

ERIC Educational Resources Information Center

Coleman, Jill S. M.; Mitchell, Melissa

2014-01-01

This article describes the implementation of high-altitude balloon (HAB) research into a variety of undergraduate atmospheric science classes as a means of increasing active student engagement in real-world, problem-solving events. Because high-altitude balloons are capable of reaching heights of 80,000-100,000 ft (24-30 km), they provide a…

White Mountain Research Station: 25 years of high-altitude research. [organization and functions of test facility for high altitude research

NASA Technical Reports Server (NTRS)

Pace, N.

1973-01-01

The organization and functions of a test facility for conducting research projects at high altitudes are discussed. The projects conducted at the facility include the following: (1) bird physiology, (2) cardiorespiratory physiology, (3) endocrinological studies, (4) neurological studies, (5) metabolic studies, and (6) geological studies.

Photocopy of drawing. ALTITUDE CHAMBERS “L” & “R” STRUCTURES. NASA, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Photocopy of drawing. ALTITUDE CHAMBERS “L” & “R” STRUCTURES. NASA, John F. Kennedy Space Center, Florida. Drawing 68-K-L-11213, NASA KSC, November, 1968. CHAMBER “R” ELEVATION. Sheet 4 - Cape Canaveral Air Force Station, Launch Complex 39, Altitude Chambers, First Street, between Avenue D and Avenue E, Cape Canaveral, Brevard County, FL

Photocopy of drawing. ALTITUDE CHAMBERS “L” & “R” STRUCTURES. NASA, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Photocopy of drawing. ALTITUDE CHAMBERS “L” & “R” STRUCTURES. NASA, John F. Kennedy Space Center, Florida. Drawing 68-K-L-11213, NASA KSC, November, 1968. WORK PLATFORM DETAIL. Sheet 6 - Cape Canaveral Air Force Station, Launch Complex 39, Altitude Chambers, First Street, between Avenue D and Avenue E, Cape Canaveral, Brevard County, FL

Photocopy of drawing. ALTITUDE CHAMBERS “L” & “R” STRUCTURES. NASA, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Photocopy of drawing. ALTITUDE CHAMBERS “L” & “R” STRUCTURES. NASA, John F. Kennedy Space Center, Florida. Drawing 68-K-L-11213, NASA KSC, November, 1968. CHAMBER “L” ELEVATION. Sheet 3 - Cape Canaveral Air Force Station, Launch Complex 39, Altitude Chambers, First Street, between Avenue D and Avenue E, Cape Canaveral, Brevard County, FL

Quadrant to Measure the Sun's Altitude

ERIC Educational Resources Information Center

Windsor, A Morgan, Jr.

2013-01-01

The changing altitude of the Sun (either over the course of a day or longer periods) is a phenomenon that students do not normally appreciate. However, the altitude of the Sun affects many topics in disciplines as diverse as astronomy, meteorology, navigation, or horology, such as the basis for seasons, determination of latitude and longitude, or…

Influence of altitude and aspect on daily variations in factors of forest fire danger

Treesearch

G. Lloyd. Hayes

1941-01-01

Altitude, in broad subdivisions, exerts recognized and well-understood effects on climate. Aspect further modifies the altitudinal influence. Many publications have dealt with the interrelations of these geographic factors with climate and life zones or have discussed variations of individual weather elements as influenced by local altitude and aspect differences and...

Peruvian Maca (Lepidium peruvianum) – III: The Effects of Cultivation Altitude on Phytochemical and Genetic Differences in the Four Prime Maca Phenotypes

PubMed Central

Meissner, Henry O.; Mscisz, Alina; Baraniak, Marek; Piatkowska, Ewa; Pisulewski, Pawel; Mrozikiewicz, Mieczyslaw; Bobkiewicz-Kozlowska, Teresa

2017-01-01

In two trials, dietary and Glucosinolates’ characteristics in four Maca phenotypes have been examined with an extension into the determination of DNA sequences. Hypocotyls of the four prime phenotypes of Peruvian Maca - Lepidium peruvianum Chacon, labelled as “Yellow”, “Black”, “Red” and “Purple” were separated from mixed Maca crops cultivated in four geographically-distant locations in the Peruvian Andes at altitudes between 2,800m and 4,300 m a.s.l. It was found that at higher altitudes where Red and Purple Maca phenotypes were grown, the significantly higher (P<0.05) Glucosinolates’ concentrations, adopted as the marker of Maca physiological activity, were observed with the Purple phenotype showing the highest Glucosinolates’ content at 4,300m a.s.l., followed by the Red-coloured hypocotyls. Black Maca showed a reversal, but also a significant (P<0.05) trend, while the Yellow phenotype showed no visible altitude-inflicted response (P>0.05) and has consistently the lowest Glucosinolates content. Thus, it is reasonable to assume that the altitude at which Red, Purple and Black phenotypes of L. peruvianum are grown, may be responsible for the variation in physiologic functionalities, leading to different than expected specific therapeutic and health benefits induced by Maca phenotypes grown at diverse altitudes. Although promising, insufficiently precise differences in DNA sequences failed to distinguish, without any reasonable doubt, four Maca phenotypes cultivated either in the same or geographically-distant locations, and harvested at different altitudes a.s.l. Further research on DNA sequences is needed, with more primers and larger number of Maca phenotypes, considering biosynthesis of secondary metabolites and adaptation pathways induced by harsh environment at altitudes where Maca is cultivated. PMID:28824342

Peruvian Maca (Lepidium peruvianum) - III: The Effects of Cultivation Altitude on Phytochemical and Genetic Differences in the Four Prime Maca Phenotypes.

PubMed

Meissner, Henry O; Mscisz, Alina; Baraniak, Marek; Piatkowska, Ewa; Pisulewski, Pawel; Mrozikiewicz, Mieczyslaw; Bobkiewicz-Kozlowska, Teresa

2017-06-01

In two trials, dietary and Glucosinolates' characteristics in four Maca phenotypes have been examined with an extension into the determination of DNA sequences. Hypocotyls of the four prime phenotypes of Peruvian Maca - Lepidium peruvianum Chacon, labelled as "Yellow", "Black", "Red" and "Purple" were separated from mixed Maca crops cultivated in four geographically-distant locations in the Peruvian Andes at altitudes between 2,800m and 4,300 m a.s.l. It was found that at higher altitudes where Red and Purple Maca phenotypes were grown, the significantly higher ( P <0.05) Glucosinolates' concentrations, adopted as the marker of Maca physiological activity, were observed with the Purple phenotype showing the highest Glucosinolates' content at 4,300m a.s.l., followed by the Red-coloured hypocotyls. Black Maca showed a reversal, but also a significant ( P <0.05) trend, while the Yellow phenotype showed no visible altitude-inflicted response ( P >0.05) and has consistently the lowest Glucosinolates content. Thus, it is reasonable to assume that the altitude at which Red, Purple and Black phenotypes of L. peruvianum are grown, may be responsible for the variation in physiologic functionalities, leading to different than expected specific therapeutic and health benefits induced by Maca phenotypes grown at diverse altitudes. Although promising, insufficiently precise differences in DNA sequences failed to distinguish, without any reasonable doubt, four Maca phenotypes cultivated either in the same or geographically-distant locations, and harvested at different altitudes a.s.l. Further research on DNA sequences is needed, with more primers and larger number of Maca phenotypes, considering biosynthesis of secondary metabolites and adaptation pathways induced by harsh environment at altitudes where Maca is cultivated.

A genome wide study of genetic adaptation to high altitude in feral Andean Horses of the páramo.

PubMed

Hendrickson, Sher L

2013-12-17

Life at high altitude results in physiological and metabolic challenges that put strong evolutionary pressure on performance due to oxidative stress, UV radiation and other factors dependent on the natural history of the species. To look for genes involved in altitude adaptation in a large herbivore, this study explored genome differentiation between a feral population of Andean horses introduced by the Spanish in the 1500s to the high Andes and their Iberian breed relatives. Using allelic genetic models and Fst analyses of ~50 K single nucleotide polymorphisms (SNPs) across the horse genome, 131 candidate genes for altitude adaptation were revealed (Bonferoni of p ≤ 2 × 10(-7)). Significant signals included the EPAS1 in the hypoxia-induction-pathway (HIF) that was previously discovered in human studies (p = 9.27 × 10(-8)); validating the approach and emphasizing the importance of this gene to hypoxia adaptation. Strong signals in the cytochrome P450 3A gene family (p = 1.5 ×10(-8)) indicate that other factors, such as highly endemic vegetation in altitude environments are also important in adaptation. Signals in tenuerin 2 (TENM2, p = 7.9 × 10(-14)) along with several other genes in the nervous system (gene categories representation p = 5.1 × 10(-5)) indicate the nervous system is important in altitude adaptation. In this study of a large introduced herbivore, it becomes apparent that some gene pathways, such as the HIF pathway are universally important for high altitude adaptation in mammals, but several others may be selected upon based on the natural history of a species and the unique ecology of the altitude environment.

Analysis of the variation of the 0°C isothermal altitude during rainfall events

NASA Astrophysics Data System (ADS)

Zeimetz, Fränz; Garcìa, Javier; Schaefli, Bettina; Schleiss, Anton J.

2016-04-01

In numerous countries of the world (USA, Canada, Sweden, Switzerland,…), the dam safety verifications for extreme floods are realized by referring to the so called Probable Maximum Flood (PMF). According to the World Meteorological Organization (WMO), this PMF is determined based on the PMP (Probable Maximum Precipitation). The PMF estimation is performed with a hydrological simulation model by routing the PMP. The PMP-PMF simulation is normally event based; therefore, if no further information is known, the simulation needs assumptions concerning the initial soil conditions such as saturation or snow cover. In addition, temperature series are also of interest for the PMP-PMF simulations. Temperature values can not only be deduced from temperature measurement but also using the temperature gradient method, the 0°C isothermal altitude can lead to temperature estimations on the ground. For practitioners, the usage of the isothermal altitude for referring to temperature is convenient and simpler because one value can give information over a large region under the assumption of a certain temperature gradient. The analysis of the evolution of the 0°C isothermal altitude during rainfall events is aimed here and based on meteorological soundings from the two sounding stations Payerne (CH) and Milan (I). Furthermore, hourly rainfall and temperature data are available from 110 pluviometers spread over the Swiss territory. The analysis of the evolution of the 0°C isothermal altitude is undertaken for different precipitation durations based on the meteorological measurements mentioned above. The results show that on average, the isothermal altitude tends to decrease during the rainfall events and that a correlation between the duration of the altitude loss and the duration of the rainfall exists. A significant difference in altitude loss is appearing when the soundings from Payerne and Milan are compared.

Division I College Football Concussion Rates Are Higher at Higher Altitudes.

PubMed

Lynall, Robert C; Kerr, Zachary Y; Parr, Matthew S; Hackney, Anthony C; Mihalik, Jason P

2016-02-01

Retrospective cohort. 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. To determine the association between concussion rates and altitude during college football games. Athletic trainers from 21 Division I football programs provided exposure and injury data to the National Collegiate Athletic Association (NCAA) Injury Surveillance Program (ISP) from the 2009-2010 to 2013-2014 academic years. The elevation of each stadium was determined. Concussion rates per 1000 athlete-exposures (AEs) were compared in 2 ways, based on the sample of stadium elevations: (1) median split (elevation higher than 178 m or lower than 178 m), and (2) quartile split. Rate ratios (RRs), rate differences, and 95% confidence intervals (CIs) were computed. One hundred sixty-nine concussions were reported over 49 040 AEs (3.45/1000 AEs). Using the median split, the concussion rate above 178 m (RR = 4.18/1000 AEs) was 1.47 times the concussion rate below 178 m (RR = 2.84/1000 AEs; 95% CI: 1.09, 2.00; P = .01). The concussion rate at the highest altitude quartile (higher than 284 m; RR = 5.01/1000 AEs) was 1.67 times greater than the concussion rate at the lowest altitude quartile (lower than 43 m; RR = 3.00/1000 AEs; 95% CI: 1.13, 2.48; P = .01). 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. Prognosis, level 2b.

Association of hemoglobin values at booking with adverse maternal outcomes among Peruvian populations living at different altitudes.

PubMed

Gonzales, Gustavo F; Tapia, Vilma; Gasco, Manuel; Carrillo, Carlos E; Fort, Alfredo L

2012-05-01

To determine hemoglobin values associated with adverse maternal outcomes among Peruvian populations at different altitudes. A retrospective cohort study was conducted using data from the Perinatal Information System. Adverse maternal outcomes were assessed. Risk of pre-eclampsia increased at maternal hemoglobin levels above 14.5 g/dL (OR 1.27; 95% CI, 1.18-1.36) or below 7.0 g/dL (OR 1.52; CI 95%, 1.08-2.14). Altitude above 2000 m reduced risk (OR 0.65; 95% CI 0.62-0.68). Risk of postpartum hemorrhage (PPH) increased with moderate/severe anemia (OR 6.15; 95% CI, 3.86-9.78) and at moderate altitudes (OR 1.26; 95% CI, 1.12-1.43). Mild anemia at any altitude was associated with reduced risk of pre-eclampsia (OR 0.85, 95% CI, 0.81-0.89) and PPH (OR 1.01; 95% CI, 0.88-1.15). Risk of premature rupture of membranes was reduced at high hemoglobin values. Maternal mortality increased at hemoglobin levels below 9.0 g/dL (OR 5.68; 95% CI, 2.97-10.80) and above 14.5 g/dL (OR 2.18; 95% CI, 1.22-3.91). Maternal mortality increased at moderate altitudes (OR 29.2; 95% CI, 2.62-324.60) and high altitudes (OR 66.4; 95% CI, 6.65-780.30) when hemoglobin levels were below 9.0 g/dL. Elevated altitude and hemoglobin levels influence maternal outcomes. Copyright © 2012 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.

Maternal hemoglobin concentration and adverse pregnancy outcomes at low and moderate altitudes in Peru.

PubMed

Gonzales, Gustavo F; Tapia, Vilma; Gasco, Manuel; Carrillo, Carlos E

2012-07-01

To identify associations of maternal hemoglobin (Hb) with perinatal outcomes at low and moderate altitudes in Peru. Study of records with sequential information using perinatal database system. The study included 295 651 pregnant women with their products. Using multiple logistic regression analysis, we estimated the probability of stillbirths, preterm and small for gestational age (SGA) births associated with maternal Hb levels at low (0-1999 m) and moderate altitudes (2000-2999 m). Maternal Hb decreased as pregnancy progressed from first to third trimester at both altitudes. Hb was higher at moderate than at low altitude (p < 0.001). Risks for stillbirths increased with low maternal Hb (odds ratio [OR]: 1.39 for Hb 9-9.9; OR: 1.84 for Hb 8-8.9; OR: 3.25 for Hb 7-7.9; and OR: 7.8 for Hb <7 g/dl); with Hb higher than 14.5 g/dl (OR: 1.31) and with altitudes ≥ 2000 m (OR: 1.2). High preterm rates were also observed with low Hbs (OR: 1.16 for Hb 9-9.9; OR: 1.64 for Hb 8-8.9; OR: 2.25 for Hb 7-7.9; and OR:2.87 for Hb<7 g/dl) and with Hb higher than 14.5 g/dl (OR: 1.14). High SGA rates were observed in neonates with maternal Hb of 7-7.9 (OR: 1.35) and <7 g/dl (OR:1.57), and higher than 14.5 g/dl (OR: 1.33), and with moderate altitudes (OR: 1.12). The cut-off points for lower risks of stillbirth and preterm births was 10 g/dl, and for SGA 9 g/dl of hemoglobin. Low and high maternal Hb levels and moderate altitude were independent risk factors for adverse perinatal outcomes.

Pharmacokinetics of Lidocaine Hydrochloride Metabolized by CYP3A4 in Chinese Han Volunteers Living at Low Altitude and in Native Han and Tibetan Chinese Volunteers Living at High Altitude.

PubMed

Zhang, Juanling; Zhu, Junbo; Yao, Xingchen; Duan, Yabin; Zhou, Xuejiao; Yang, Meng; Li, Xiangyang

2016-01-01

To investigate the pharmacokinetics of lidocaine hydrochloride metabolized by cytochrome P450 3A4 (CYP3A4) in Chinese Han volunteers living at low altitude (LA) and in native Han and Tibetan Chinese volunteers living at high altitude, lidocaine hydrochloride 10 mg was given by intramuscular injection to 3 groups: Han volunteers living at LA, and native Han and Tibetan volunteers living at a high altitude. Blood samples were collected before the (baseline) study drug was given and at 0.25, 0.5, 1.0, 1.5, 2.0, 3.0, 4.0, 6.0, 8.0 h after study drug administration. Lidocaine hydrochloride in plasma was determined by RP-HPLC. Pharmacokinetics parameters of lidocaine hydrochloride showed that there were no significant difference between the native Han and Tibetan volunteers, but the t(1/2) was 29.8 and 29.8% higher in 2 groups, respectively, than in the LA group. To study related mechanism, the effects of exposure to chronic high-altitude hypoxia (CHH) on the activity and expression of CYP3A1 were examined in rats. Rats were divided into LA, chronic moderate altitude hypoxia, and CHH groups. CHH caused significant decreases in the activity and protein and mRNA expression of rat CYP3A1 in vivo. This study found significant changes in the disposition of lidocaine hydrochloride in native healthy Tibetan and Han Chinese subjects living at a high altitude in comparison to healthy Han Chinese subjects living at LA, it might be due to significant decreases in the activity and protein and mRNA expression of CYP3A4 under CHH condition. © 2016 S. Karger AG, Basel.

Management of high altitude pulmonary edema in the Himalaya: a review of 56 cases presenting at Pheriche medical aid post (4240 m).

PubMed

Jones, Barbara E; Stokes, Suzy; McKenzie, Suzi; Nilles, Eric; Stoddard, Gregory J

2013-03-01

The purpose of this study was to review the patient characteristics and management of 56 cases of high altitude pulmonary edema at the Pheriche Himalayan Rescue Association Medical Aid Post, and to measure the use of medications in addition to descent and oxygen. In a retrospective case series, we reviewed all patients diagnosed clinically with high altitude pulmonary edema during the 2010 Spring and Fall seasons. Nationality, altitude at onset of symptoms, physical examination findings, therapies administered, and evacuation methods were evaluated. Of all patients, 23% were Nepalese, with no difference in clinical features compared with non-Nepalese patients; 28% of all patients were also suspected of having high altitude cerebral edema. Symptoms developed in 91% of all patients at an altitude higher than the aid post (median altitude of onset of 4834 m); 83% received oxygen therapy, and 87% received nifedipine, 44% sildenafil, 32% dexamethasone, and 39% acetazolamide. Patients who were administered sildenafil, dexamethasone, or acetazolamide had presented with significantly lower initial oxygen saturations (P ≤ .05). After treatment, 93% of all patients descended; 38% descended on foot without a supply of oxygen. A significant number of patients presenting to the Pheriche medical aid post with high altitude pulmonary edema were given dexamethasone, sildenafil, or acetazolamide in addition to oxygen, nifedipine, and descent. This finding may be related to perceived severity of illness and evacuation limitations. Although no adverse effects were observed, the use of multiple medications is not supported by current evidence and should not be widely adopted without further study. Copyright © 2013 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

A Start Toward Micronucleus-Based Decompression Models; Altitude Decompression

NASA Technical Reports Server (NTRS)

Van Liew, H. D.; Conkin, Johnny

2007-01-01

Do gaseous micronuclei trigger the formation of bubbles in decompression sickness (DCS)? Most previous instructions for DCS prevention have been oriented toward supersaturated gas in tissue. We are developing a mathematical model that is oriented toward the expected behavior of micronuclei. The issue is simplified in altitude decompressions because the aviator or astronaut is exposed only to decompression, whereas in diving there is a compression before the decompression. The model deals with four variables: duration of breathing of 100% oxygen before going to altitude (O2 prebreathing), altitude of the exposure, exposure duration, and rate of ascent. Assumptions: a) there is a population of micronuclei of various sizes having a range of characteristics, b) micronuclei are stable until they grow to a certain critical nucleation radius, c) it takes time for gas to diffuse in or out of micronuclei, and d) all other variables being equal, growth of micronuclei upon decompression is more rapid at high altitude because of the rarified gas in the micronuclei. To estimate parameters, we use a dataset of 4,756 men in altitude chambers exposed to various combinations of the model s variables. The model predicts occurrence of DCS symptoms quite well. It is notable that both the altitude chamber data and the model show little effect of O2 prebreathing until it lasts more than 60 minutes; this is in contrast to a conventional idea that the benefit of prebreathing is directly due to exponential washout of tissue nitrogen. The delay in response to O2 prebreathing can be interpreted as time required for outward diffusion of nitrogen; when the micronuclei become small enough, they are disabled, either by crushing or because they cannot expand to a critical nucleation size when the subject ascends to altitude.

Geographic Variation in Mentally Unhealthy Days: Air Pollution and Altitude Perspectives.

PubMed

Ha, Hoehun

2017-09-01

Ha, Hoehun. Geographic variation in mentally unhealthy days: air pollution and altitude perspectives. High Alt Med Biol. 18:258-266, 2017. Mental health incorporates our emotional, psychological, and social well-being and it is critical at each phase of life, from youth and preadulthood through adulthood. We assessed the association between mentally unhealthy days (MUDs), air pollutant concentrations, and altitude on the basis of cross-county studies. Data on poor mental health days for the United States were based on health-related telephone surveys conducted by the Behavioral Risk Factor Surveillance System (BRFSS). Average annual regional air pollution data were obtained from Center for Disease Control and Prevention (CDC) WONDER Environmental data, and altitude data were collected from the U.S. Geological Survey (USGS). In the data set (across 2589 U.S. counties for 2011), even after accounting for potential confounding variables and multicollinearity, a significant association between altitude, air pollution, and poor mental health days was found, explaining that poor mental health days increase with increasing air pollution concentrations and with decreasing altitude (R 2  = 0.663, p < 0.001). Controlling for socioeconomic (e.g., education and employment) and social (including social relationship and crime) factors did not change these findings. In this study, we found that counties with lower air pollution and higher altitude had significantly lower average number of MUDs reported within the past 30 days. This association has not been reported before in the literature. These findings suggest a need for further investigation into the extent that air quality and altitude may serve as significant factors for mental health and have major implications in our understanding of the etiology of mental health by medical professionals.

The impact of altitude on the sleep of young elite soccer players (ISA3600)

PubMed Central

Sargent, Charli; Schmidt, Walter F; Aughey, Robert J; Bourdon, Pitre C; Soria, Rudy; Claros, Jesus C Jimenez; Garvican-Lewis, Laura A; Buchheit, Martin; Simpson, Ben M; Hammond, Kristal; Kley, Marlen; Wachsmuth, Nadine; Gore, Christopher J; Roach, Gregory D

2013-01-01

Background Altitude training is used by elite athletes to improve sports performance, but it may also disrupt sleep. The aim of this study was to examine the effects of 2 weeks at high altitude on the sleep of young elite athletes. Methods Participants (n=10) were members of the Australian under-17 soccer team on an 18-day (19-night) training camp in Bolivia, with six nights at near sea level in Santa Cruz (430 m) and 13 nights at high altitude in La Paz (3600 m). Sleep was monitored using polysomnography during a baseline night at 430 m and three nights at 3600 m (immediately after ascent, 1 week after ascent and 2 weeks after ascent). Data were analysed using effect size statistics. Results All results are reported as comparisons with baseline. Rapid eye movement (REM) sleep was likely lower immediately upon ascent to altitude, possibly lower after 1 week and similar after 2 weeks. On all three nights at altitude, hypopneas and desaturations were almost certainly higher; oxygen saturation was almost certainly lower; and central apnoeas, respiratory arousals and periodic breathing were very likely higher. The effects on REM sleep were common to all but one participant, but the effects on breathing were specific to only half the participants. Conclusions The immediate effects of terrestrial altitude of 3600 m are to reduce the amount of REM sleep obtained by young elite athletes, and to cause 50% of them to have impaired breathing during sleep. REM sleep returns to normal after 2 weeks at altitude, but impaired breathing does not improve. PMID:24282215

Sildenafil has little influence on cardiovascular hemodynamics or 6-km time trial performance in trained men and women at simulated high altitude.

PubMed

Jacobs, Kevin A; Kressler, Jochen; Stoutenberg, Mark; Roos, Bernard A; Friedlander, Anne L

2011-01-01

Sildenafil improves maximal exercise capacity at high altitudes (∼4350-5800 m) by reducing pulmonary arterial pressure and enhancing oxygen delivery, but the effects on exercise performance at less severe altitudes are less clear. To determine the effects of sildenafil on cardiovascular hemodynamics (heart rate, stroke volume, and cardiac output), arterial oxygen saturation (SaO2), and 6-km time-trial performance of endurance-trained men and women at a simulated altitude of ∼3900 m. Twenty men and 15 women, endurance-trained, completed one experimental exercise trial (30 min at 55% of altitude-specific capacity +6-km time trial) at sea level (SL) and two trials at simulated high altitude (HA) while breathing hypoxic gas (12.8% FIo2) after ingestion of either placebo or 50 mg sildenafil in double-blind, randomized, and counterbalanced fashion. Maximal exercise capacity and SaO2 were significantly reduced at HA compared to SL (18%-23%), but sildenafil did not significantly improve cardiovascular hemodynamics or time-trial performance in either men or women compared to placebo and only improved SaO2 in women (4%). One male subject (5% of male subjects, 2.8% of all subjects) exhibited a meaningful 36-s improvement in time-trial performance with sildenafil compared to placebo. In this group of endurance trained men and women, sildenafil had very little influence on cardiovascular hemodynamics, SaO2, and 6-km time-trial performance at a simulated altitude of ∼3900 m. It appears that a very small percentage of endurance-trained men and women derive meaningful improvements in aerobic performance from sildenafil at a simulated altitude of ∼3900 m.

In vitro fermentation characteristics and effective utilisable crude protein in leaves and green pods of Moringa stenopetala and Moringa oleifera cultivated at low and mid-altitudes.

PubMed

Melesse, A; Steingass, H; Boguhn, J; Rodehutscord, M

2013-06-01

This study was conducted to assess the in vitro nutrient digestibility and utilisation of leaves and green pods of two Moringa species in supplementing the feed of ruminant animals during the dry season. Samples were analysed for proximate nutrients using official methods. The metabolisable energy (ME), organic matter digestibility (OMD) and effective utilisable crude protein (uCP) were estimated using the Hohenheim in vitro gas test method. Gas volume in Moringa stenopetala leaves and green pods was generally higher than those of Moringa oleifera. Gas volume for leaves was similar between low and mid-altitudes but was higher for green pods at mid-altitude. M. stenopetala leaves contained significantly higher ME (9.8 MJ/kg DM) and OMD (75%) than those of M. oleifera. Similarly, M. stenopetala green pods had higher ME and OMD values than those of M. oleifera. For green pods, the ME and OMD values were significantly higher at mid-altitude than those at low altitude although these values for leaves were similar between both altitudes. Moringa oleifera leaves had higher effective uCP than those of M. stenopetala. Nevertheless, the effective uCP was higher for green pods of M. stenopetala than those of M. oleifera. The effective uCP for leaves cultivated at mid-altitude was slightly higher than those at low altitude. This study suggested that leaves and green pods could be used as alternative energy and protein supplements for tropical ruminants, particularly during dry periods. It was further concluded that leaves were generally better in nutrient compositions and in vitro nutrient digestibility characteristics than green pods. © 2012 Blackwell Verlag GmbH.

Sustained sympathetic activity in altitude acclimatizing lowlanders and high-altitude natives.

PubMed

Lundby, C; Calbet, J; van Hall, G; Saltin, B; Sander, M

2018-03-01

Combined results from different independent studies suggest that acclimatization to high altitude induces a slowly developing sympathetic activation, even at levels of hypoxia that cause no acute chemoreflex-mediated sympathoexcitation. We here provide direct neurophysiological evidence for this phenomenon. In eight Danish lowlanders, we quantified mean arterial blood pressure (MAP), heart rate (HR), and muscle sympathetic nerve activity (MSNA), twice at sea level (normoxia and with acute hypoxic exposure to 12.6% O 2 ) and twice at high altitude (after 10 and 50 days of exposure to 4100 m). Measurements were also obtained in eight Bolivian highlanders on one occasion at high altitude. Acute hypoxic exposure caused no increase in MSNA (15 ± 2 vs 16 ± 2 bursts per min, respectively, and also MAP and HR remained stable). In contrast, from sea level to 10 and 50 days in high-altitude increases were observed in MAP: 72 ± 2 vs 78 ± 2 and 75 ± 2 mm Hg; HR: 54 ± 3 vs 67 ± 3 and 65 ± 3 beats per min; MSNA: 15 ± 2 vs 42 ± 5 and 42 ± 5 bursts per min, all P < .05. Bolivian subjects had high levels of MSNA: 34 ± 4 bursts per min. The simultaneous increase in MAP, HR, and MSNA suggests high altitude-induced sympathetic activity, which is sustained in well-acclimatized lowlanders. The high MSNA levels in the Bolivian highlanders suggest lifelong sympathetic activation at high altitude. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Neutral Wind Observations below 200 km altitudes

NASA Astrophysics Data System (ADS)

Watanabe, S.; Abe, T.; Habu, H.; Kakinami, Y.; Larsen, M. F.; Pfaff, R. F., Jr.; Yamamoto, M.

2015-12-01

Neutral Wind Observations below 200 km altitudesS. Watanabe1, T. Abe2, H. Habu2, Y. Kakinami3, M. Larsen4, R. Pfaff5, M. Yamamoto6, M-Y. Yamamoto31Hokkaido University/Hokkaido Information University, 2JAXA/ISAS, 3Kochi University of Technology, 4Clemson University, 5NASA/Goddard Space Flight Center, 6Kyoto University, Neutral wind in the thermosphere is one of the key parameters to understand the ionosphere-thermosphere coupling process. JAXA/ISAS successfully launched sounding rockets from Uchinoura Space Center (USC) on September 2, 2007, January 12, 2012, and July 20, 2013, and NASA launched sounding rockets from Kwajalein on May 7, 2013 and from Wallops on July 4, 2013. The rockets installed Lithium and/or TMA canisters as well as instruments for plasma and electric and magnetic fields. The atomic Lithium gases were released at altitudes between 150 km and 300 km in the evening on September 2, 2007, at altitude of ~100 km in the morning on January 12, 2012, at altitude of ~120km in the midnight on July 20, 2013, at altitude between 150 km and 300 km in the evening on May 7, 2013 and at altitude of ~150 km in the noon on July 4, 2013. The Lithium atoms were scattering sunlight by resonance scattering with wavelength of 670nm. However, the Lithium atoms scattered moon light on July 20, 2013. The moon light scattering is the first time to use for thermospheric wind measurement in the midnight. The Lithium clouds/trails and TMA trails showed clearly the neutral wind shears and atmospheric waves at ~150 km altitude in the lower thermosphere for all local time.

Observation of a 27-day solar signature in noctilucent cloud altitude

NASA Astrophysics Data System (ADS)

Köhnke, Merlin C.; von Savigny, Christian; Robert, Charles E.

2018-05-01

Previous studies have identified solar 27-day signatures in several parameters in the Mesosphere/Lower thermosphere region, including temperature and Noctilucent cloud (NLC) occurrence frequency. In this study we report on a solar 27-day signature in NLC altitude with peak-to-peak variations of about 400 m. We use SCIAMACHY limb-scatter observations from 2002 to 2012 to detect NLCs. The superposed epoch analysis method is applied to extract solar 27-day signatures. A 27-day signature in NLC altitude can be identified in both hemispheres in the SCIAMACHY dataset, but the signature is more pronounced in the northern hemisphere. The solar signature in NLC altitude is found to be in phase with solar activity and temperature for latitudes ≳ 70 ° N. We provide a qualitative explanation for the positive correlation between solar activity and NLC altitude based on published model simulations.

Effect of chronic altitude hypoxia on hematologic and glycolytic parameters.

PubMed

Clench, J; Ferrell, R E; Schull, W J

1982-05-01

The physiological effect of chronic exposure to altitude hypoxia on the glycolytic intermediates, adenosine triphosphate and 2,3-diphosphoglyceric acid, and the hematologic parameters, hemoglobin, hematocrit, and mean cell hemoglobin concentration, has been examined in an indigenous population, the Aymara, of the Departamento de Arica, Chile. This population normally resides at three altitudes: the coast (0-500 m), the sierra (2,500-3,500 m), and the altiplano (above 4,200 m). After isolation of altitude from other environmental factors (age, sex, body build, ethnicity, smoking, and residential permanence), an increase in 2,3-diphosphoglycerate and a decrease in adenosine triphosphate was observed. Both hemoglobin and hematocrit increased as expected, but mean cell hemoglobin concentration declined. It is proposed that a decline in the activity of a single enzyme, pyruvate kinase, can account for these observed changes and suggests a pivotal role for pyruvate kinase in the physiological adaptation to altitude hypoxia.

Launching rockets and small satellites from the lunar surface

NASA Technical Reports Server (NTRS)

Anderson, K. A.; Dougherty, W. M.; Pankow, D. H.

1985-01-01

Scientific payloads and their propulsion systems optimized for launch from the lunar surface differ considerably from their counterparts for use on earth. For spin-stabilized payloads, the preferred shape is a large diameter-to-length ratio to provide stability during the thrust phase. The rocket motor required for a 50-kg payload to reach an altitude of one lunar radius would have a mass of about 41 kg. To place spin-stabilized vehicles into low altitude circular orbits, they are first launched into an elliptical orbit with altitude about 840 km at aposelene. When the spacecraft crosses the desired circular orbit, small retro-rockets are fired to attain the appropriate direction and speed. Values of the launch angle, velocity increments, and other parameters for circular orbits of several altitudes are tabulated. To boost a 50-kg payload into a 100-km altitude circular orbit requires a total rocket motor mass of about 90 kg.

Launching rockets and small satellites from the lunar surface

NASA Astrophysics Data System (ADS)

Anderson, K. A.; Dougherty, W. M.; Pankow, D. H.

Scientific payloads and their propulsion systems optimized for launch from the lunar surface differ considerably from their counterparts for use on earth. For spin-stabilized payloads, the preferred shape is a large diameter-to-length ratio to provide stability during the thrust phase. The rocket motor required for a 50-kg payload to reach an altitude of one lunar radius would have a mass of about 41 kg. To place spin-stabilized vehicles into low altitude circular orbits, they are first launched into an elliptical orbit with altitude about 840 km at aposelene. When the spacecraft crosses the desired circular orbit, small retro-rockets are fired to attain the appropriate direction and speed. Values of the launch angle, velocity increments, and other parameters for circular orbits of several altitudes are tabulated. To boost a 50-kg payload into a 100-km altitude circular orbit requires a total rocket motor mass of about 90 kg.

The yak genome and adaptation to life at high altitude.

PubMed

Qiu, Qiang; Zhang, Guojie; Ma, Tao; Qian, Wubin; Wang, Junyi; Ye, Zhiqiang; Cao, Changchang; Hu, Quanjun; Kim, Jaebum; Larkin, Denis M; Auvil, Loretta; Capitanu, Boris; Ma, Jian; Lewin, Harris A; Qian, Xiaoju; Lang, Yongshan; Zhou, Ran; Wang, Lizhong; Wang, Kun; Xia, Jinquan; Liao, Shengguang; Pan, Shengkai; Lu, Xu; Hou, Haolong; Wang, Yan; Zang, Xuetao; Yin, Ye; Ma, Hui; Zhang, Jian; Wang, Zhaofeng; Zhang, Yingmei; Zhang, Dawei; Yonezawa, Takahiro; Hasegawa, Masami; Zhong, Yang; Liu, Wenbin; Zhang, Yan; Huang, Zhiyong; Zhang, Shengxiang; Long, Ruijun; Yang, Huanming; Wang, Jian; Lenstra, Johannes A; Cooper, David N; Wu, Yi; Wang, Jun; Shi, Peng; Wang, Jian; Liu, Jianquan

2012-07-01

Domestic yaks (Bos grunniens) provide meat and other necessities for Tibetans living at high altitude on the Qinghai-Tibetan Plateau and in adjacent regions. Comparison between yak and the closely related low-altitude cattle (Bos taurus) is informative in studying animal adaptation to high altitude. Here, we present the draft genome sequence of a female domestic yak generated using Illumina-based technology at 65-fold coverage. Genomic comparisons between yak and cattle identify an expansion in yak of gene families related to sensory perception and energy metabolism, as well as an enrichment of protein domains involved in sensing the extracellular environment and hypoxic stress. Positively selected and rapidly evolving genes in the yak lineage are also found to be significantly enriched in functional categories and pathways related to hypoxia and nutrition metabolism. These findings may have important implications for understanding adaptation to high altitude in other animal species and for hypoxia-related diseases in humans.

Collision probability at low altitudes resulting from elliptical orbits

NASA Technical Reports Server (NTRS)

Kessler, Donald J.

1990-01-01

The probability of collision between a spacecraft and another object is calculated for various altitude and orbit conditions, and factors affecting the probability are discussed. It is shown that a collision can only occur when the spacecraft is located at an altitude which is between the perigee and apogee altitudes of the object and that the probability per unit time is largest when the orbit of the object is nearly circular. However, at low altitudes, the atmospheric drag causes changes with time of the perigee and the apogee, such that circular orbits have a much shorter lifetime than many of the elliptical orbits. Thus, when the collision probability is integrated over the lifetime of the orbiting object, some elliptical orbits are found to have much higher total collision probability than circular orbits. Rocket bodies used to boost payloads from low earth orbit to geosynchronous orbit are an example of objects in these elliptical orbits.

Differences in the day and night longwave fluxes at satellite altitude for sun-synchronous NOAA-9 nonscanning sensors

NASA Technical Reports Server (NTRS)

Pandey, Dhirendra K.; Paden, Jack; Lee, Robert B., III

1990-01-01

The outgoing LW flux determined by using the data measured by four nonscanning sensors at satellite altitude is reported. The outgoing LW fluxes for MFOV and WFOV sensors at satellite altitude are determined by subtracting the SW fluxes from the total sensors. Results for 1985 and 1986 are discussed. The nighttime LW flux determined by using the MFOV-T channel at the satellite altitude is found to be constant from month to month within 1 W/sq m, while the LW flux from WFOV-T channel varies within 2 to 3 W sq m. The high value for the WFOV-T channel is attributed to the effects of sun-blips on the measurements involved. The main advantage of using day/night longwave flux differences at satellite altitude is that the consistencies of nonscanner sensors can be checked very quickly.

Splenic infarction associated with sickle cell trait at low altitude.

PubMed

Seegars, Mary Beth; Brett, Allan S

2015-12-01

Sickle cell trait is widely known to be associated with splenic infarction at high altitudes. Although textbooks and reviews imply that this complication does not occur at low altitudes, we encountered such a case and identified several previous cases in the literature. An 18-year-old woman with sickle cell trait who resided near sea level presented with left upper quadrant abdominal pain and was found to have multiple splenic infarcts. She was otherwise well, with no comorbidities that would predispose to hypoxemia or vascular injury. A review of the literature revealed 12 previously published cases of low-altitude splenic infarction in patients with sickle trait; 7 of those patients had comorbidities that likely predisposed to splenic infarction. None. Spontaneous splenic infarction can occur in patients with sickle trait who live at low altitudes. It is unclear whether this complication is rare, or whether it is relatively common but under-recognized.

Flight test evaluation of an RAF high altitude partial pressure protective assembly

NASA Technical Reports Server (NTRS)

Ashworth, G. R.; Putnam, T. W.; Dana, W. J.; Enevoldson, E. K.; Winter, W. R.

1979-01-01

A partial pressure suit was evaluated during tests in an F-104 and F-15 as a protective garment for emergency descents. The garment is an pressure jerkin and modified anti-g suit combined with an oronasal mask. The garment can be donned and doffed at the aircraft to minimize thermal buildup. The oronasal mask was favored by the pilots due to its immobility on the face during high g-loading. The garment was chosen to provide optimum dexterity for the pilot, which is not available in a full pressure suit, while protecting the pilot at altitudes up to 18,288 meters, during a cabin decompression, and subsequent aircraft descent. During cabin decompressions in the F-104 and F-15, cabin pressure altitude was measured at various aircraft angles of attack, Mach numbers, and altitudes to determine the effect of the aerodynamic slipstream on the cabin altitude.

High-altitude cerebral oedema mimicking stroke.

PubMed

Yanamandra, Uday; Gupta, Amul; Patyal, Sagarika; Varma, Prem Prakash

2014-03-26

High-altitude cerebral oedema (HACO) is the most fatal high-altitude illness seen by rural physicians practising in high-altitude areas. HACO presents clinically with cerebellar ataxia, features of raised intracranial pressure (ICP) and coma. Early identification is important as delay in diagnosis can be fatal. We present two cases of HACO presenting with focal deficits mimicking stroke. The first patient presented with left-sided hemiplegia associated with the rapid deterioration in the sensorium. Neuroimaging revealed features suggestive of vasogenic oedema. The second patient presented with monoplegia of the lower limb. Neuroimaging revealed perfusion deficit in anterior cerebral artery territory. Both patients were managed with dexamethasone and they improved dramatically. Clinical picture and neuroimaging closely resembled acute ischaemic stroke in both cases. Thrombolysis in these patients would have been disastrous. Recent travel to high altitude, young age, absence of atherosclerotic risk factors and features of raised ICP concomitantly directed the diagnosis to HACO.

Preparing for Hiking and Rock-Climbing At Altitude

NASA Technical Reports Server (NTRS)

Greenleaf, John E.

2002-01-01

Exposure to altitude with or without exercise usually results in body dehydration. Psychological and physiological preparation for exercise at altitude involves consideration of maintaining body warmth in a cool to cold environment with progressively lower oxygen content (partial pressure) as altitude increases. However, this discussion will focus on altitudes below 14,000 it where supplemental breathing oxygen is not required for sojourns of healthy people. Background information and helpful advice for those who exercise in the cold can be found in selected articles in the 2001 Winter Issue of this Newsletter: M.B. Ducharme, Get ready for outdoor winter play: prepare yourself for the cold; C. O'Brien, Think layers when dressing for exercise in the cold; B.G. Rice and R. Ellis, Let it snow, let it snow, let it snow - but be aware of winter hazards; and L.B. Mayers, Exercise - induced asthma.

Depth Distribution Of The Maxima Of Extensive Air Shower

NASA Technical Reports Server (NTRS)

Adams, J. H.; Howell, L. W.

2003-01-01

Observations of the extensive air showers from space can be free from interference by low altitude clouds and aerosols if the showers develop at a sufficiently high altitude. In this paper we explore the altitude distribution of shower maxima to determine the fraction of all showers that will reach their maxima at sufficient altitudes to avoid interference from these lower atmosphere phenomena. Typically the aerosols are confined within a planetary boundary layer that extends from only 2-3 km above the Earth's surface. Cloud top altitudes extend above 15 km but most are below 4 km. The results reported here show that more than 75% of the showers that will be observed by EUSO have maxima above the planetary boundary layer. The results also show that more than 50% of the showers that occur on cloudy days have their maxima above the cloud tops.

The radiation protection problems of high altitude and space flight

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fry, R.J.M.

1993-04-01

This paper considers the radiation environment in aircraft at high altitudes and spacecraft in low earth orbit and in deep space and the factors that influence the dose equivalents. Altitude, latitude and solar cycle are the major influences for flights below the radiation belts. In deep space, solar cycle and the occurrence of solar particle events are the factors of influence. The major radiation effects of concern are cancer and infertility in males. In high altitude aircraft the radiation consists mainly of protons and neutrons, with neutrons contributing about half the equivalent dose. The average dose rate at altitudes ofmore » transcontinental flights that approach the polar regions are greater by a factor of about 2.5 than on routes at low latitudes. Current estimates of does to air crews suggest they are well within the ICRP (1990) recommended dose limits for radiation workers.« less

The effect of α1 -adrenergic blockade on post-exercise brachial artery flow-mediated dilatation at sea level and high altitude.

PubMed

Tymko, Michael M; Tremblay, Joshua C; Hansen, Alex B; Howe, Connor A; Willie, Chris K; Stembridge, Mike; Green, Daniel J; Hoiland, Ryan L; Subedi, Prajan; Anholm, James D; Ainslie, Philip N

2017-03-01

Our objective was to quantify endothelial function (via brachial artery flow-mediated dilatation) at sea level (344 m) and high altitude (3800 m) at rest and following both maximal exercise and 30 min of moderate-intensity cycling exercise with and without administration of an α 1 -adrenergic blockade. Brachial endothelial function did not differ between sea level and high altitude at rest, nor following maximal exercise. At sea level, endothelial function decreased following 30 min of moderate-intensity exercise, and this decrease was abolished with α 1 -adrenergic blockade. At high altitude, endothelial function did not decrease immediately after 30 min of moderate-intensity exercise, and administration of α 1 -adrenergic blockade resulted in an increase in flow-mediated dilatation. Our data indicate that post-exercise endothelial function is modified at high altitude (i.e. prolonged hypoxaemia). The current study helps to elucidate the physiological mechanisms associated with high-altitude acclimatization, and provides insight into the relationship between sympathetic nervous activity and vascular endothelial function. We examined the hypotheses that (1) at rest, endothelial function would be impaired at high altitude compared to sea level, (2) endothelial function would be reduced to a greater extent at sea level compared to high altitude after maximal exercise, and (3) reductions in endothelial function following moderate-intensity exercise at both sea level and high altitude are mediated via an α 1 -adrenergic pathway. In a double-blinded, counterbalanced, randomized and placebo-controlled design, nine healthy participants performed a maximal-exercise test, and two 30 min sessions of semi-recumbent cycling exercise at 50% peak output following either placebo or α 1 -adrenergic blockade (prazosin; 0.05 mg kg  -1 ). These experiments were completed at both sea-level (344 m) and high altitude (3800 m). Blood pressure (finger photoplethysmography), heart rate (electrocardiogram), oxygen saturation (pulse oximetry), and brachial artery blood flow and shear rate (ultrasound) were recorded before, during and following exercise. Endothelial function assessed by brachial artery flow-mediated dilatation (FMD) was measured before, immediately following and 60 min after exercise. Our findings were: (1) at rest, FMD remained unchanged between sea level and high altitude (placebo P = 0.287; prazosin: P = 0.110); (2) FMD remained unchanged after maximal exercise at sea level and high altitude (P = 0.244); and (3) the 2.9 ± 0.8% (P = 0.043) reduction in FMD immediately after moderate-intensity exercise at sea level was abolished via α 1 -adrenergic blockade. Conversely, at high altitude, FMD was unaltered following moderate-intensity exercise, and administration of α 1 -adrenergic blockade elevated FMD (P = 0.032). Our results suggest endothelial function is differentially affected by exercise when exposed to hypobaric hypoxia. These findings have implications for understanding the chronic impacts of hypoxaemia on exercise, and the interactions between the α 1 -adrenergic pathway and endothelial function. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

Recent Elevation Changes on Bagley Ice Valley, Guyot and Yahtse Glaciers, Alaska, from ICESat Altimetry, Star-3i Airborne, and SRTM Spaceborne DEMs

NASA Astrophysics Data System (ADS)

Muskett, R. R.; Sauber, J. M.; Lingle, C. S.; Rabus, B. T.; Tangborn, W. V.; Echelmeyer, K. A.

2005-12-01

Three- to 5-year surface elevation changes on Bagley Ice Valley, Guyot and Yahtse Glaciers, in the eastern Chugach and St. Elias Mtns of south-central Alaska, are estimated using ICESat-derived data and digital elevation models (DEMs) derived from interferometric synthetic aperture radar (InSAR) data. The surface elevations of these glaciers are influenced by climatic warming superimposed on surge dynamics (in the case of Bagley Ice Valley) and tidewater glacier dynamics (in the cases of Guyot and Yahtse Glaciers) in this coastal high-precipitation regime. Bagley Ice Valley / Bering Glacier last surged in 1993-95. Guyot and Yahtse Glaciers, as well as the nearby Tyndell Glacier, have experienced massive tidewater retreat during the past century, as well as during recent decades. The ICESat-derived elevation data we employ were acquired in early autumn in both 2003 and 2004. The NASA/NIMA Shuttle Radar Topography Mission (SRTM) DEM that we employ was derived from X-band InSAR data acquired during this 11-22 Feb. 2000 mission and processed by the German Aerospace Center. This DEM was corrected for estimated systematic error, and a mass balance model was employed to account for seasonal snow accumulation. The Star-3i airborne, X-band, InSAR-derived DEM that we employ was acquired 4-13 Sept. 2000 by Intermap Technologies, Inc., and was also processed by them. The ICESat-derived profiles crossing Bagley Ice Valley, differenced with Star-3i DEM elevations, indicate preliminary mean along-profile elevation increases of 5.6 ± 3.4 m at 1315 m altitude, 7.4 ± 2.7 m at 1448 m altitude, 4.7 ± 1.9 m at 1557 m altitude, 1.3 ± 1.4 m at 1774 m altitude, and 2.5 ± 1.5 m at 1781 m altitude. This is qualitatively consistent with the rising surface on Bagley Ice Valley observed by Muskett et al. [2003]. The ICESat-derived profiles crossing Yahtse Glacier, differenced with the SRTM DEM elevations, indicate preliminary mean elevation changes (negative implies decrease) of -0.9 ± 3.5 m at 1562 m altitude, -2.6 ± 2.8 m at 1378 m altitude, 6.1 ± 3.5 m at 1142 m altitude, 1.4 ± 12.1 m at 1232 m altitude, -4.0 ± 4.2 m at 250 m to 1217 m altitude, -1.8 ± 3.3 m at 1200 m altitude, and 8.0 ± 6.4 m at 940 m altitude. One ICESat-derived track-to-DEM comparison on Guyot Glacier indicates a preliminary mean elevation change in the 478 m to 1150 m altitude range of -2.8 ± 14.1 m. Results, including additional comparisons to small-aircraft laser altimeter data, with more fully-corrected for estimated snow and ice accumulation / ablation between acquisitions times, will be presented. [Muskett, R.R., C.S. Lingle, W.V. Tangborn, and B.T. Rabus, Multi-decadal elevation changes on Bagley Ice Valley and Malaspina Glacier, Alaska, GRL, 30 (16), 1857, doi:10.1029/2003GL017707, 2003.

The effect of α1‐adrenergic blockade on post‐exercise brachial artery flow‐mediated dilatation at sea level and high altitude

PubMed Central

Tremblay, Joshua C.; Hansen, Alex B.; Howe, Connor A.; Willie, Chris K.; Stembridge, Mike; Green, Daniel J.; Hoiland, Ryan L.; Subedi, Prajan; Anholm, James D.; Ainslie, Philip N.

2016-01-01

Key points Our objective was to quantify endothelial function (via brachial artery flow‐mediated dilatation) at sea level (344 m) and high altitude (3800 m) at rest and following both maximal exercise and 30 min of moderate‐intensity cycling exercise with and without administration of an α1‐adrenergic blockade.Brachial endothelial function did not differ between sea level and high altitude at rest, nor following maximal exercise.At sea level, endothelial function decreased following 30 min of moderate‐intensity exercise, and this decrease was abolished with α1‐adrenergic blockade. At high altitude, endothelial function did not decrease immediately after 30 min of moderate‐intensity exercise, and administration of α1‐adrenergic blockade resulted in an increase in flow‐mediated dilatation.Our data indicate that post‐exercise endothelial function is modified at high altitude (i.e. prolonged hypoxaemia). The current study helps to elucidate the physiological mechanisms associated with high‐altitude acclimatization, and provides insight into the relationship between sympathetic nervous activity and vascular endothelial function. Abstract We examined the hypotheses that (1) at rest, endothelial function would be impaired at high altitude compared to sea level, (2) endothelial function would be reduced to a greater extent at sea level compared to high altitude after maximal exercise, and (3) reductions in endothelial function following moderate‐intensity exercise at both sea level and high altitude are mediated via an α1‐adrenergic pathway. In a double‐blinded, counterbalanced, randomized and placebo‐controlled design, nine healthy participants performed a maximal‐exercise test, and two 30 min sessions of semi‐recumbent cycling exercise at 50% peak output following either placebo or α1‐adrenergic blockade (prazosin; 0.05 mg kg −1). These experiments were completed at both sea‐level (344 m) and high altitude (3800 m). Blood pressure (finger photoplethysmography), heart rate (electrocardiogram), oxygen saturation (pulse oximetry), and brachial artery blood flow and shear rate (ultrasound) were recorded before, during and following exercise. Endothelial function assessed by brachial artery flow‐mediated dilatation (FMD) was measured before, immediately following and 60 min after exercise. Our findings were: (1) at rest, FMD remained unchanged between sea level and high altitude (placebo P = 0.287; prazosin: P = 0.110); (2) FMD remained unchanged after maximal exercise at sea level and high altitude (P = 0.244); and (3) the 2.9 ± 0.8% (P = 0.043) reduction in FMD immediately after moderate‐intensity exercise at sea level was abolished via α1‐adrenergic blockade. Conversely, at high altitude, FMD was unaltered following moderate‐intensity exercise, and administration of α1‐adrenergic blockade elevated FMD (P = 0.032). Our results suggest endothelial function is differentially affected by exercise when exposed to hypobaric hypoxia. These findings have implications for understanding the chronic impacts of hypoxaemia on exercise, and the interactions between the α1‐adrenergic pathway and endothelial function. PMID:28032333

75 FR 18047 - Amendment of Low Altitude Area Navigation Route T-254; Houston, TX

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-09

...-0015; Airspace Docket No. 09-ASW-18] RIN 2120-AA66 Amendment of Low Altitude Area Navigation Route T... action amends low altitude Area Navigation (RNAV) route T-254 in the Houston, TX, terminal area by... the College Station, TX, VORTAC. The FAA is taking this action to eliminate a portion of T-254 that is...

40 CFR 85.1515 - Emission standards and test procedures applicable to imported nonconforming motor vehicles and...

Code of Federal Regulations, 2011 CFR

2011-07-01

... All light-duty vehicles shall meet the applicable emission standards at both low and high-altitudes... sold to, or owned by, an importer for principal use at other than a designated high-altitude location... at a designated high-altitude location beginning with the 1988 model year. 4 All 1982 OP year and...

76 FR 13078 - Airworthiness Directives; Eclipse Aerospace, Inc. Model EA500 Airplanes Equipped With a Pratt and...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-10

... operating altitude of 37,000 feet into Section 2, Limitations, of the airplane flight manual (AFM). This AD requires you to incorporate operating limitations of maximum operating altitude of 30,000 feet into Section... due to hard carbon build up blocking the static vanes has continued to occur at 37,000 feet altitude...

Cosmic Rays with Portable Geiger Counters: From Sea Level to Airplane Cruise Altitudes

ERIC Educational Resources Information Center

Blanco, Francesco; La Rocca, Paola; Riggi, Francesco

2009-01-01

Cosmic ray count rates with a set of portable Geiger counters were measured at different altitudes on the way to a mountain top and aboard an aircraft, between sea level and cruise altitude. Basic measurements may constitute an educational activity even with high school teams. For the understanding of the results obtained, simulations of extensive…

Photocopy of drawing. ALTITUDE CHAMBERS “L” & “R” STRUCTURES. NASA, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Photocopy of drawing. ALTITUDE CHAMBERS “L” & “R” STRUCTURES. NASA, John F. Kennedy Space Center, Florida. Drawing 68-K-L-11213, NASA KSC, March, 1971. DOOR LATCH MECHANISM & DOOR LATCHING RATCHET. Sheet 14 - Cape Canaveral Air Force Station, Launch Complex 39, Altitude Chambers, First Street, between Avenue D and Avenue E, Cape Canaveral, Brevard County, FL

Altitude valve for railway suspension control system

NASA Astrophysics Data System (ADS)

Zhang, Xuan; Zhang, Lihao; Li, Qingxuan; Chen, WanSong

2017-09-01

With the variation of people and material during vehicle service, the gravity of vehicle could be unbalanced. As a result it might cause accident. In order to solve this problem, altitude valve is assembled on board. It can adjust the gravity of vehicle by the intake and outlet progress of the spring in the altitude valve to prevent the tilt of vehicles.

Integration of radar altimeter, precision navigation, and digital terrain data for low-altitude flight

NASA Technical Reports Server (NTRS)

Zelenka, Richard E.

1992-01-01

A Kalman filter for the integration of a radar altimeter into a terrain database-dependent guidance system was developed. Results obtained from a low-altitude helicopter flight test data acquired over moderately rugged terrain showed that the proposed Kalman filter removes large disparities in predicted above-ground-level (AGL) altitude in the presence of measurement anomalies and dropouts. Integration of a radar altimeter makes it possible to operate a near-terrain guidance system at or below 50 ft (subject to obstacle-avoidance limitations), whereas without radar altimeter integration, a minimum clearance altitude of 220 AGL is needed, as is suggested by previous work.

Climatology and trends of mesospheric (58-90) temperatures based upon 1982-1986 SME limb scattering profiles

NASA Technical Reports Server (NTRS)

Clancy, R. Todd; Rusch, David W.

1989-01-01

Atmospheric temperature profiles for the altitude range 58-90 km were calculated using data on global UV limb radiances from the SME satellite. The major elements of this climatology include a high vertical resolution (about 4 km) and the coverage of the 70-90 km altitude region. The analysis of this extensive data set provides a global definition of mesospheric-lower thermospheric temperature trends over the 1982-1986 period. The observations suggest a pattern of 1-2 K/year decreases in temperatures at 80-90-km altitudes accompanied by 0.5-1.5 K/year increases in temperatures at 65-80-km altitudes.

Preliminary Performance Data on General Electric Integrated Electronic Control Operating on J47 RX1-3 Turbojet Engine in NACA Altitude Wind Tunnel

NASA Technical Reports Server (NTRS)

Blivas, Darnold; Taylor, Burt L., III

1950-01-01

Performance data obtained with recording oscillographs are presented to show the transient response of the General Electric Integrated Electronic Control operating on the J47 RXl-3 turbo-Jet engine over a range of altitudes from 10,000 to 45,000 feet and at ram pressure ratios of 1.03 and 1.4. These data represent the performance of the final control configuration developed after an investigation of the engine transient behavior in the NACA altitude wind tunnel. Oscillograph traces of controlled accelerations (throttle bursts),oontrolled decelerations (throttle chops), and controlled altitude starts are presented.

Elliptical orbit performance computer program

NASA Technical Reports Server (NTRS)

Myler, T. R.

1981-01-01

A FORTRAN coded computer program which generates and plots elliptical orbit performance capability of space boosters for presentation purposes is described. Orbital performance capability of space boosters is typically presented as payload weight as a function of perigee and apogee altitudes. The parameters are derived from a parametric computer simulation of the booster flight which yields the payload weight as a function of velocity and altitude at insertion. The process of converting from velocity and altitude to apogee and perigee altitude and plotting the results as a function of payload weight is mechanized with the ELOPE program. The program theory, user instruction, input/output definitions, subroutine descriptions and detailed FORTRAN coding information are included.

An inventory of aeronautical ground research facilities. Volume 2: Air breathing engine test facilities

NASA Technical Reports Server (NTRS)

Pirrello, C. J.; Hardin, R. D.; Heckart, M. V.; Brown, K. R.

1971-01-01

The inventory covers free jet and direct connect altitude cells, sea level static thrust stands, sea level test cells with ram air, and propulsion wind tunnels. Free jet altitude cells and propulsion wind tunnels are used for evaluation of complete inlet-engine-exhaust nozzle propulsion systems under simulated flight conditions. These facilities are similar in principal of operation and differ primarily in test section concept. The propulsion wind tunnel provides a closed test section and restrains the flow around the test specimen while the free jet is allowed to expand freely. A chamber of large diameter about the free jet is provided in which desired operating pressure levels may be maintained. Sea level test cells with ram air provide controlled, conditioned air directly to the engine face for performance evaluation at low altitude flight conditions. Direct connect altitude cells provide a means of performance evaluation at simulated conditions of Mach number and altitude with air supplied to the flight altitude conditions. Sea level static thrust stands simply provide an instrumented engine mounting for measuring thrust at zero airspeed. While all of these facilities are used for integrated engine testing, a few provide engine component test capability.

Associations among cataract prevalence, sunlight hours, and altitude in the Himalayas.

PubMed

Brilliant, L B; Grasset, N C; Pokhrel, R P; Kolstad, A; Lepkowski, J M; Brilliant, G E; Hawks, W N; Pararajasegaram, R

1983-08-01

The relationship between cataract prevalence, altitude, and sunlight hours was investigated in a large national probability sample survey of 105 sites in the Himalayan kingdom of Nepal, December 1980 through April 1981. Cataract of senile or unknown etiology was diagnosed by ophthalmologists in 873 of 30,565 full-time life-long residents of survey sites. Simultaneously, the altitude of sites was measured using a standard mountain altimeter. Seasonally adjusted average daily duration of sunlight exposure for each site was calculated by a method which took into account latitude and obstructions along the skyline. Age- and sex-standardized cataract prevalence was 2.7 times higher in sites at an altitude of 185 meters or less than in sites over 1000 meters. Cataract prevalence was negatively correlated with altitude (r = -0.533, p less than 0.0001). However, a positive correlation between cataract prevalence and sunlight was observed (r = 0.563, p less than 0.0001). Sites with an average of 12 hours of sunlight exposure had 3.8 times as much cataract as sites with an average of only seven hours of exposure. Sunlight was blocked from reaching certain high altitude sites by tall neighboring mountains.

SEM Imaging and Chemical Analysis of Aerosol Particles from Surface and Hi-altitudes in New Jersey.

NASA Astrophysics Data System (ADS)

Bandamede, M.; Boaggio, K.; Bancroft, L.; Hurler, K.; Magee, N. B.

2016-12-01

We report on Scanning Electron Microscopy analysis of aerosol particle morphology and chemistry. The work includes the first comparative SEM analysis of aerosol particles captured by balloon at high altitude. The particles were acquired in an urban/suburban environment in central New-Jersey. Particles were sampled from near the surface using ambient air filtration and at high-altitudes using a novel balloon-borne instrument (ICE-Ball, see abstract by K. Boaggio). Particle images and 3D geometry are acquired by a Hitachi SU-5000 SEM, with resolution to approximately 3 nm. Elemental analysis on particles is provided by Energy Dispersive X-Ray Spectroscopy (EDS, EDAX, Inc.). Uncoated imaging is conducted in low vacuum within the variable-pressure SEM, which provides improved detection and analysis of light-element compositions including Carbon. Preliminary results suggest that some similar particle types and chemical species are sampled at both surface and high-altitude. However, as expected, particle morphologies, concentrations, chemistry, and apparent origin vary significantly at different altitudes and under different atmospheric flow regimes. Improved characterization of high-altitude aerosol particles, and differences from surface particulate composition, may advance inputs for atmospheric cloud and radiation models.

Negative Association of Hospital Efficiency Under Increasing Geographic Elevation on Acute Myocardial Infarction In-Patient Mortality.

PubMed

Devaraj, Srikant; Patel, Pankaj C

Although variation in-patient outcomes based on hospitals' geographic location has been studied, altitude of hospitals above sea level may also affect patient outcomes. Possibly, because of negative physical and psychological effects of altitude on hospital employees, hospital efficiency may decline at higher altitudes. Greater focus on hospital efficiency, despite decreasing efficiency at higher altitudes, could increase demands on hospital employees and further deteriorate patient outcomes. Using data envelopment analysis on a sample of 840 hospital-year observations representing 95,504 patients with acute myocardial infarction (AMI) in the United States, and controlling for patient, hospital, and county characteristics and controlling for hospital, state, and year fixed effects, we find support for the negative association between hospital altitude and efficiency; for 1 percentage point increase in efficiency and every 1,000 feet increase in altitude above the sea level, the mortality of patients with AMI increases by 0.66 percentage points. The findings have implications for hospital performance at increasing geographic elevation and introduces to the literature the notion of "health economics of elevation," to suggest that elevation of a hospital may be an important criterion for consideration for policy makers and insurance firms.

Genetic Diversity of Plasmodium falciparum Merozoite Surface Protein-1 Block 2 in Sites of Contrasting Altitudes and Malaria Endemicities in the Mount Cameroon Region

PubMed Central

Wanji, Samuel; Kengne-Ouafo, Arnaud J.; Joan Eyong, Ebanga E.; Kimbi, Helen K.; Tendongfor, Nicholas; Ndamukong-Nyanga, Judith L.; Nana-Djeunga, Hugues C.; Bourguinat, Catherine; Sofeu-Feugaing, David D.; Charvet, Claude L.

2012-01-01

The present study analyzed the relationship between the genetic diversity of Plasmodium falciparum and parasitologic/entomologic indices in the Mount Cameroon region by using merozoite surface protein 1 as a genetic marker. Blood samples were collected from asymptomatic children from three altitude zones (high, intermediate, and low). Parasitologic and entomologic indices were determined by microscopy and landing catch mosquito collection/circumsporozoite protein–enzyme-linked immunosorbent assay, respectively. A total of 142 randomly selected P. falciparum-positive blood samples were genotyped by using a nested polymerase chain reaction–based technique. K-1 polymerase chain reaction products were also sequenced. As opposed to high altitude, the highest malaria prevalence (70.65%) and entomologic inoculation rate (2.43 infective/bites/night) were recorded at a low altitude site. Seven (18.91%), 22 (36.66%), and 19 (42.22%) samples from high, intermediate, and low altitudes, respectively, contained multiclonal infections. A new K-1 polymorphism was identified. This study shows a positive non-linear association between low/intermediate altitude (high malaria transmission) and an increase in P. falciparum merozoite surface protein 1 block 2 polymorphisms. PMID:22556072

Subjective and objective convergence of the eyes at simulated altitude of 18,000 feet preceded by short-term exposure to heat stress.

PubMed

Sinha, Biswajit; Dubey, D K

2014-01-01

Armed forces personnel including military aviators are quite often exposed concurrently to various environmental stressors like high environmental temperature and hypoxia. Literatures have suggested that exposure to one environmental stressor may modify the physiological response on subsequent exposure to same or different stressor. The present study was undertaken to investigate the impact of cross tolerance between two environmental stressors of aviation (heat and hypoxia) in ten healthy adult males in a simulated altitude chamber in a within subject experimental study. They were assessed for their convergence ability of the eyes at ground and at simulated altitude of 18,000 ft with or without pre-exposure to heat stress. Subjective convergence at simulated altitude of 18,000 ft did not show any improvement following pre-exposure to heat stress. Objective convergence was improved following pre-exposure to heat stress and was found to be 10.76 cm and 9.10 cm without and with heat stress respectively at simulated altitude of 18,000 ft. Improved objective convergence at high altitude as a result of pre-exposure to heat stress is indicative of better ocular functions. This might benefit aviators while flying at hypoxic condition.

Construction of the Propulsion Systems Laboratory No. 1 and 2

NASA Image and Video Library

1951-01-21

Construction of the Propulsion Systems Laboratory No. 1 and 2 at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. When it began operation in late 1952, the Propulsion Systems Laboratory was the NACA’s most powerful facility for testing full-scale engines at simulated flight altitudes. The facility contained two altitude simulating test chambers which were a technological combination of the static sea-level test stands and the complex Altitude Wind Tunnel, which recreated actual flight conditions on a larger scale. NACA Lewis began designing the new facility in 1947 as part of a comprehensive plan to improve the altitude testing capabilities across the lab. The exhaust, refrigeration, and combustion air systems from all the major test facilities were linked. In this way, different facilities could be used to complement the capabilities of one another. Propulsion Systems Laboratory construction began in late summer 1949 with the installation of an overhead exhaust pipe connecting the facility to the Altitude Wind Tunnel and Engine Research Building. The large test section pieces arriving in early 1951, when this photograph was taken. The two primary coolers for the altitude exhaust are in place within the framework near the center of the photograph.

Airborne reconnaissance in the civilian sector - Agricultural monitoring from high-altitude powered platforms

NASA Technical Reports Server (NTRS)

Youngblood, J. W.; Jackson, R. D.

1983-01-01

Design concepts and mission applications for unmanned high-altitude powered platforms (HAPPs) are discussed. A chemically powered HAPP (operating altitude 18-21 km, wingspan 26 m, payload 91 kg, endurance 2-3 days) would use current turboprop technology. A microwave-powered HAPP (operating altitude around 21 km, wingspan 57.9 m, payload 500 kg, endurance weeks or months) would circle within or perform boost-glide maneuvers around a microwave beam of density 1.1 kw/sq m. Of two solar-powered-HAPP designs presented, the more promising uses five vertical solar-panel-bearing fins, two of which can be made horizontal at night, (wingspan 57.8/98.3 m, payload 113 kg, endurance weeks or months). The operating altitude depends on the latitude and season: this HAPP design is shown to be capable of year-round 20-km-altitude flights over the San Joaquin Valley in California, where an agricultural-monitoring mission using Landsat-like remote sensors is proposed. Other applications may be better served by the characteristics of the other HAPPs. The primary advantage of HAPPs over satellites is found to be their ability to provide rapidly available high-resolution continuous or repetitive coverage of specific areas at relatively low cost.

A strategy for oxygen conditioning at high altitude: comparison with air conditioning.

PubMed

West, John B

2015-09-15

Large numbers of people live or work at high altitude, and many visit to trek or ski. The inevitable hypoxia impairs physical working capacity, and at higher altitudes there is also cognitive impairment. Twenty years ago oxygen enrichment of room air was introduced to reduce the hypoxia, and this is now used in dormitories, hotels, mines, and telescopes. However, recent advances in technology now allow large amounts of oxygen to be obtained from air or cryogenic oxygen sources. As a result it is now feasible to oxygenate large buildings and even institutions such as hospitals. An analogy can be drawn between air conditioning that has improved the living and working conditions of millions of people who live in hot climates and oxygen conditioning that can do the same at high altitude. Oxygen conditioning is similar to air conditioning except that instead of cooling the air, the oxygen concentration is raised, thus reducing the equivalent altitude. Oxygen conditioning on a large scale could transform living and working conditions at high altitude, where it could be valuable in homes, hospitals, schools, dormitories, company headquarters, banks, and legislative settings. Copyright © 2015 the American Physiological Society.

Genetic diversity of Plasmodium falciparum merozoite surface protein-1 block 2 in sites of contrasting altitudes and malaria endemicities in the Mount Cameroon region.

PubMed

Wanji, Samuel; Kengne-Ouafo, Arnaud J; Eyong, Ebanga E Joan; Kimbi, Helen K; Tendongfor, Nicholas; Ndamukong-Nyanga, Judith L; Nana-Djeunga, Hugues C; Bourguinat, Catherine; Sofeu-Feugaing, David D; Charvet, Claude L

2012-05-01

The present study analyzed the relationship between the genetic diversity of Plasmodium falciparum and parasitologic/entomologic indices in the Mount Cameroon region by using merozoite surface protein 1 as a genetic marker. Blood samples were collected from asymptomatic children from three altitude zones (high, intermediate, and low). Parasitologic and entomologic indices were determined by microscopy and landing catch mosquito collection/circumsporozoite protein-enzyme-linked immunosorbent assay, respectively. A total of 142 randomly selected P. falciparum-positive blood samples were genotyped by using a nested polymerase chain reaction-based technique. K-1 polymerase chain reaction products were also sequenced. As opposed to high altitude, the highest malaria prevalence (70.65%) and entomologic inoculation rate (2.43 infective/bites/night) were recorded at a low altitude site. Seven (18.91%), 22 (36.66%), and 19 (42.22%) samples from high, intermediate, and low altitudes, respectively, contained multiclonal infections. A new K-1 polymorphism was identified. This study shows a positive non-linear association between low/intermediate altitude (high malaria transmission) and an increase in P. falciparum merozoite surface protein 1 block 2 polymorphisms.

Lidar observations of high altitude cirrus near the tropical tropopause

NASA Astrophysics Data System (ADS)

Parameswaran, K.; Kumar, S. Sunil; Krishna Murthy, B.

High altitude cirrus plays a significant role in atmospheric chemistry, radiation and troposphere-stratosphere exchanges. Studies on their global morphology using satellite data (SAGE) suggests that over the tropics these clouds occur quite frequently in the altitude region around 14 to 16 km with favoured locations centred over Southern Asia, India and Mexico. A monostatic Nd:YAG lidar (operating at 532 nm wavelength) located at National MST Radar Facility (NMRF), Gadanki (13.5°N, 79.2°E) provides an excellent opportunity to study the properties of these clouds. Lidar observations for ~120 nights during the period January 1999 to March 2000 are used to investigate the physical and optical properties of these clouds aswell as their spatial (altitude) and temporal variability. Based on optical depth ( c ) cirrus clouds are classified as Sub-visual Cirrus (SVC) with c 0.03, Thin Cirrus (TC) with 0.030.3. While SVCs are observed anywhere in the altitude region 12 to 18 km, with favoured altitude above 15 km, TCs and DCs usually occur around 14.5+/-1km. The altitude region 14 to 16km appears to be more conducive for cirrus formation. Even though the geometrical thickness (vertical extent) of these clouds varies from 0.3 to 3 km, they are mostly confined to altitudes below the level of tropopause temperature inversion. The cloud optical depth maximises around the post-mid-night period. These clouds also introduce significant depolarisation for the backscattered radiation indicating presence of abundant non-spherical particles presumably ice-crystals. Under favourable conditions these ice-crystals get aligned horizontally to enhance the co - polarized component of lidar backscatter signal through specular reflection, leading to a decrease in cloud depolarisation () below the ambient molecular depolarisation (m ). Such conditions are usually encountered in the case of optically dense clouds. Altitude profile of backscatter ratio within the cloud shows that the cloud is not optically symmetric with respect to the geometric centre. This asymmetry parameter () of the cloud shows significant temporal variability. For clouds with> m , as c increases, the optical centre descends in altitude and for clouds with< m the optical centre ascends as c increases. Occurrence of cirrus clouds and their optical properties are found to be closely associated with the characteristics of atmospheric turbulence in the upper troposphere.

Effects of high altitude and water deprivation on arginine vasopressin release in men.

PubMed

Maresh, C M; Kraemer, W J; Judelson, D A; VanHeest, J L; Trad, L; Kulikowich, J M; Goetz, K L; Cymerman, A; Hamilton, A J

2004-01-01

High-altitude exposure changes the distribution of body water and electrolytes. Arginine vasopressin (AVP) may influence these alterations. The purpose of this study was to examine the effect of a 24-h water deprivation trial (WDT) on AVP release after differing altitude exposures. Seven healthy males (age 22 +/- 1 yr, height 176 +/- 2 cm, mass 75.3 +/- 1.8 kg) completed three WDTs: at sea level (SL), after acute altitude exposure (2 days) to 4,300 m (AA), and after prolonged altitude exposure (20 days) to 4,300 m (PA). Body mass, standing and supine blood pressures, plasma osmolality (Posm), and plasma AVP (PAVP) were measured at 0, 12, 16, and 24 h of each WDT. Urine volume was measured at each void throughout testing. Baseline Posm increased from SL to altitude (SL 291.7 +/- 0.8 mosmol/kgH2O, AA 299.6 +/- 2.2 mosmol/kgH2O, PA 302.3 +/- 1.5 mosmol/kgH2O, P < 0.05); however, baseline PAVP measurements were similar. Despite similar Posm values, the maximal PAVP response during the WDT (at 16 h) was greater at altitude than at SL (SL 1.7 +/- 0.5 pg/ml, AA 6.4 +/- 0.7 pg/ml, PA 8.7 +/- 0.9 pg/ml, P < 0.05). In conclusion, hypoxia appeared to alter AVP regulation by raising the osmotic threshold and increasing AVP responsiveness above that threshold.

Amelioration of rCBF and PbtO2 following TBI at high altitude by hyperbaric oxygen pre-conditioning.

PubMed

Hu, Shengli; Li, Fei; Luo, Haishui; Xia, Yongzhi; Zhang, Jiuquan; Hu, Rong; Cui, Gaoyu; Meng, Hui; Feng, Hua

2010-03-01

Hypobaric hypoxia at high altitude can lead to brain damage and pre-conditioning with hyperbaric oxygen (HBO) can reduce ischemic/hypoxic brain injury. This study investigates the effects of high altitude on traumatic brain injury (TBI) and examines the neuroprotection provided by HBO preconditioning against TBI. Rats were randomly divided into four groups: HBO pre-conditioning group (HBOP, n=10), high altitude group (HA, n=10), plain control group (PC, n=10) and plain sham operation group (sham, n=10). All groups were subjected to head trauma by weight drop device except for the sham group. Rats from each group were examined for neurological function, regional cerebral blood flow (rCBF) and brain tissue oxygen pressure (PbtO(2)) and were killed for analysis by transmission electron microscope. The score of neurological deficits in the HA group was highest, followed by the HBOP group and the PC group, respectively. Both rCBF and PbtO(2) were the lowest in the HA group. Brain morphology and structure seen via the transmission electron microscope was diminished in the HA group, while fewer pathological injuries occurred in the HBOP and PC groups. High altitude aggravates TBI significantly and HBO pre-conditioning can attenuate TBI in rats at high altitude by improvement of rCBF and PbtO(2). Pre-treatment with HBO might be beneficial for people traveling to high altitude locations.

Influence of growing altitude, shade and harvest period on quality and biochemical composition of Ethiopian specialty coffee.

PubMed

Tolessa, Kassaye; D'heer, Jolien; Duchateau, Luc; Boeckx, Pascal

2017-07-01

Coffee quality is a key characteristic for the international market, comprising cup quality and chemical bean constituents. In Ethiopia, using total specialty cup scores, coffees are grouped into Q1 (specialty 1) ≥ 85 and Q2 (80-84.75). This classification results in market segmentation and higher prices. Although different studies have evaluated the effects of altitude and shade on bean quality, optimum shade levels along different altitudinal ranges are not clearly indicated. Information on effects of harvest periods on coffee quality is also scanty. The present study examined the influences of these factors and their interactions on Ethiopian coffee quality RESULTS: Coffee from high altitude with open or medium shade and early to middle harvest periods had a superior bean quality. These growing conditions also favoured the production of beans with lower caffeine. An increasing altitude, from mid to high, at approximately 400 m, decreased caffeine content by 10%. At high altitude, dense shade decreased Q1 coffee by 50%. Compared to late harvesting, early harvesting increased the percentage from 27% to 73%. At mid altitude, > 80% is Q2 coffee. Changes of quality scores driven by altitude, shade and harvest period are small, although they may induce dramatic switches in the fraction Q1 versus Q2 coffee. The latter affects both farmers' profits and competitiveness in international markets. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Can people with Raynaud's phenomenon travel to high altitude?

PubMed

Luks, Andrew M; Grissom, Colin K; Jean, Dominique; Swenson, Erik R

2009-01-01

To determine whether high altitude travel adversely affects mountain enthusiasts with Raynaud's phenomenon. Volunteers with Raynaud's phenomenon were recruited using announcements disseminated by organizations dedicated to climbing or wilderness travel and Internet discussion boards dedicated to mountain activities to complete an online, anonymous survey. Survey questions addressed demographic variables, aspects of their Raynaud's phenomenon, and features of their mountain activities. Respondents compared experiences with Raynaud's phenomenon between high (>2440 m; 8000 feet) and low elevations and rated agreement with statements concerning their disease and the effects of high altitude. One hundred forty-two people, 98% of whom had primary Raynaud's phenomenon, completed the questionnaire. Respondents spent 5 to 7 days per month at elevations above 2440 m and engaged in 5.4 +/- 2.0 different activities. Eighty-nine percent of respondents engaged in winter sports and only 22% reported changing their mountain activities because of Raynaud's phenomenon. Respondents reported a variety of tactics to prevent and treat Raynaud's attacks, but only 12% used prophylactic medications. Fifteen percent of respondents reported an episode of frostbite following a Raynaud's phenomenon attack at high altitude. There was considerable heterogeneity in participants' perceptions of the frequency, duration, and severity of attacks at high altitude compared to their home elevation. Motivated individuals with primary Raynaud's phenomenon, employing various prevention and treatment strategies, can engage in different activities, including winter sports, at altitudes above 2440 m. Frostbite may be common in this population at high altitude, and care must be taken to prevent its occurrence.