Zeitschriftenartikel zum Thema „Altitude“
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Tang, Yan Fei, Chao Ding, Ya Ping He, De Chuang Zhou und Jian Wang. „Studies on the Effect of Altitude on the Flammable Liquids' Flash Point“. Advanced Materials Research 908 (März 2014): 345–48. http://dx.doi.org/10.4028/www.scientific.net/amr.908.345.
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Presented in this paper is part of an experimental series conducted at different altitudes to investigate the influence of altitude on the flammable liquids flash point. The BS-1 closed bomb apparatus is used to measure the flash points of two flammable liquids (dimethylacetylamide (DMA) and RP-5 Jet A) in a hypobaric chamber under the altitude change from 4860 km to the sea level. The experimental results show that the flash points of DMA and Jet A decrease linearly with the increase in altitude in the low altitude region below the corresponding critical altitudes but non-linearly above. The critical altitudes for DMA and RP-5 Jet A are found to be 3 km and 3.83 km respectively. When the altitude reaches or surpasses the critical altitude, the flash point decreases rapidly. In particular, the flash point of the DMA exhibits a peculiar sudden transition above the critical altitude.
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Nazarali, Samir, Henry Liu, Maleeha Syed, Terry Wood, Samuel Asanad, Alfredo A. Sadun und Rustum Karanjia. „Aircraft Cabin Pressurization and Concern for Non-Arteritic Anterior Ischemic Optic Neuropathy“. Aerospace Medicine and Human Performance 91, Nr. 9 (01.09.2020): 715–19. http://dx.doi.org/10.3357/amhp.5498.2020.
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BACKGROUND: Cabin pressurization is the process by which aircraft maintain a comfortable and safe environment for passengers flying at high altitudes. At high altitudes, most patients can tolerate changes in pressurization; however, passengers at high risk of hypoxia may experience ischemic events. The purpose of this study was to evaluate variations in pressurization of commercial aircraft at cruising altitude and describe its relevance in relation to patients with non-arteritic anterior ischemic optic neuropathy (NAION).METHODS: Altimeters were used to measure altitude and cabin altitude at cruising altitude aboard 113 commercial flights, including 53 narrow-body and 60 wide-body aircraft.RESULTS: Cabin altitude ranged from 4232 ft to 7956 ft at cruising altitudes ranging from 30,000 ft to 41,000 ft. The mean cabin altitude for all flights was 6309 876 ft. Narrow-body aircraft had a significantly higher mean cabin altitude (6739 829 ft) compared to wide-body aircraft (5929 733 ft). For all flights, the mean cruising altitude was 35,369 2881 ft with narrow-body aircraft cruising at a lower altitude of 34,238 2389 ft compared to wide-body aircraft at 36,369 2925 ft. Newer generation aircraft had a mean cabin altitude of 6066 837 ft, which was lower than the mean cabin altitude of older aircraft (6616 835 ft).DISCUSSION: Innovation in flight design has offered the ability for aircraft to fly at greater altitudes while maintaining lower cabin altitude. Those at high risk of hypoxia-induced complications may consider aircraft type when air travel is required.Nazarali S, Liu H, Syed M, Wood T, Asanad S, Sadun AA, Karanjia R. Aircraft cabin pressurization and concern for non-arteritic anterior ischemic optic neuropathy. Aerosp Med Hum Perform. 2020; 91(9):715719.
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PANKAJ PANWAR, SHARMISTHA PAL, NANCY LORIA, MED RAM VERMA, N.M. ALAM, V.K. BHATT und N.K. SHARMA. „Spatio-temporal variability of climatic parameters across different altitudes of North- Western Himalaya“. Journal of Agrometeorology 21, Nr. 3 (10.11.2021): 297–306. http://dx.doi.org/10.54386/jam.v21i3.252.
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Climate change impact varies across different altitudinal ranges and demands local specific management strategies for water resource and farming system management. The present study analyses spacio-temporal climate parameters across different altitudes of Himachal Pradesh a hilly state of India. Analysis shows that annually, minimum temperature has significantly decreased by -0.09°C at altitude I (350 - 400 m) while maximum temperature has significantly increased by 0.05°C at altitudes I and II (1400-1500 m) and decreased significantly by -0.08°C at altitude III (2000- 2100 m). Higher regions Altitude – IV (2900-3000 m) received lowest rainfall (746.1 mm) with 30.2 % variation. Seasonal rainfall variability was higher in post monsoon (102 - 174%) and least in monsoon (21 - 57%). Annual rainfall at altitude I is strongly irregular (PCI 20.1 to 22.3), followed by altitude – IV (PCI 15-25); altitude – II irregular (PCI 15-20) and altitude – III moderate to irregular (PCI 12 -19) rainfall. Seasonal Index values for four altitudes fall between 0.91-0.96 revealed that rainfall is irregular and markedly seasonal with longer drier season. Higher wavelet powers in altitude - I and II after 2005 suggests frequency of extreme rainfall occurrence had increased.
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Chapman, Robert F., Trine Karlsen, Geir K. Resaland, R. L. Ge, Matthew P. Harber, Sarah Witkowski, James Stray-Gundersen und Benjamin D. Levine. „Defining the “dose” of altitude training: how high to live for optimal sea level performance enhancement“. Journal of Applied Physiology 116, Nr. 6 (15.03.2014): 595–603. http://dx.doi.org/10.1152/japplphysiol.00634.2013.
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Chronic living at altitudes of ∼2,500 m causes consistent hematological acclimatization in most, but not all, groups of athletes; however, responses of erythropoietin (EPO) and red cell mass to a given altitude show substantial individual variability. We hypothesized that athletes living at higher altitudes would experience greater improvements in sea level performance, secondary to greater hematological acclimatization, compared with athletes living at lower altitudes. After 4 wk of group sea level training and testing, 48 collegiate distance runners (32 men, 16 women) were randomly assigned to one of four living altitudes (1,780, 2,085, 2,454, or 2,800 m). All athletes trained together daily at a common altitude from 1,250–3,000 m following a modified live high-train low model. Subjects completed hematological, metabolic, and performance measures at sea level, before and after altitude training; EPO was assessed at various time points while at altitude. On return from altitude, 3,000-m time trial performance was significantly improved in groups living at the middle two altitudes (2,085 and 2,454 m), but not in groups living at 1,780 and 2,800 m. EPO was significantly higher in all groups at 24 and 48 h, but returned to sea level baseline after 72 h in the 1,780-m group. Erythrocyte volume was significantly higher within all groups after return from altitude and was not different between groups. These data suggest that, when completing a 4-wk altitude camp following the live high-train low model, there is a target altitude between 2,000 and 2,500 m that produces an optimal acclimatization response for sea level performance.
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Zhu, Lu-lu, Zhi-jun Ma, Ming Ren, Yu-miao Wei, Yu-hua Liao, You-lu Shen, Shi-ming Fan et al. „Distinct Features of Gut Microbiota in High-Altitude Tibetan and Middle-Altitude Han Hypertensive Patients“. Cardiology Research and Practice 2020 (21.11.2020): 1–15. http://dx.doi.org/10.1155/2020/1957843.
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Indigenous animals show unique gut microbiota (GM) in the Tibetan plateau. However, it is unknown whether the hypertensive indigenous people in plateau also have the distinct gut bacteria, different from those living in plains. We sequenced the V3-V4 region of the gut bacteria 16S ribosomal RNA (rRNA) gene of feces samples among hypertensive patients (HPs) and healthy individuals (HIs) from 3 distinct altitudes: Tibetans from high altitude (3600–4500 m, n = 38 and 34), Hans from middle altitude (2260 m, n = 49 and 35), and Hans from low altitude (13 m, n = 34 and 35) and then analyzed the GM composition among hypertensive and healthy subgroups using the bioinformatics analysis, respectively. The GM of high-altitude Tibetan and middle-altitude Han HPs presented greater α- and β-diversities, lower ratio of Firmicutes/Bacteroidetes (F/B), and higher abundance of beneficial Verrucomicrobia and Akkermansia than the low-altitudes HPs did. The GM of high-altitude Tibetan and middle-altitude HIs showed greater α-diversity and lower ratio of F/B than the low-altitudes HIs did. But, β-diversity and abundance of Verrucomicrobia and Akkermansia among different subgroups of HIs did not show any differences. Conclusively, the high-altitude Tibetan and middle-altitude Han HPs have a distinct feature of GM, which may be important in their adaptation to hypertension in the plateau environments.
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Bogar, K., und P. Schatz. „Altitude and Concussions in the NFL: Is There Really a “Mile-High” Effect?“ Archives of Clinical Neuropsychology 34, Nr. 5 (Juli 2019): 759. http://dx.doi.org/10.1093/arclin/acz026.29.
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Abstract Purpose The literature on altitude and concussions in football shows some evidence of protective effects of living and training and playing at high altitudes. We explored the likelihood of sustaining concussions within the AFC West division, specifically comparing games hosted at high altitude in Denver versus games hosted by at low altitudes in Los Angeles, Oakland, and Kansas City. Methods Information was recorded for all regular season AFC West division games (N= 42) occurring in the 2012–2018 seasons. Altitude for each stadium was calculated using DaftLogic’s Google Sandbox. Concussion incidence for the 2012–2018 seasons was collected from PBS Frontline’s Concussion-Watch and weekly injury reports (NFL.com). Chi-square analyses compared likelihood of: concussions occurring in High Altitude versus Low Altitude, a Broncos player sustaining a concussion in High Altitude versus Low Altitude, and a non-Broncos AFC West player sustain a concussion in High Altitude versus Low Altitude. Results Chi-square analyses revealed no greater likelihood of players sustaining concussions in High Altitude versus Low Altitude (p=.35), or of Broncos (p=1.00) or non-Broncos (p=.47) AFC West players sustaining concussions in High Altitude versus Low Altitude. Conclusion Altitude is not a significant factor for increased likelihood of concussions, and popular theories such as “the mile-high effect” are not supported by the data. We found no evidence for the proposed protective factor of living and training at high altitude for Broncos team members, as they showed an equal likelihood of sustaining a concussion at high and low altitude.
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Lei, Tian, Jinliang Xu, Xingli Jia, Leyu Wei und Lin Tian. „Impact of High-Altitude on Truck’s Climbing Speed: Case study in Qinghai-Tibet Plateau Area in China“. Journal of Advanced Transportation 2019 (20.08.2019): 1–14. http://dx.doi.org/10.1155/2019/8560204.
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Truck’s climbing performance is an important consideration in traffic safety, efficiency, and highway geometric design. With the infrastructure development in high-altitude area in China, more attention needs to be paid on truck’s climbing performance in such area. In this article, truck’s climbing speed in high-altitude area was examined through field tests on different grade sections at different altitudes. Truck’s speed-distance curves were built at different altitudes and the impact of altitude on truck’s climbing speed was explored based on the test results. It was shown that, within the altitude range of 3000~5000m, altitude had an obvious influence on test truck’s decelerating and accelerating performance. Truck’s speed decreased faster on steep grades and increased slower on gentle grades with the increase of the altitude. Also, the stable speed that test truck could maintain on a certain grade was lower at a higher altitude. In addition, test truck’s theoretical speed-distance curves at the sea level were estimated through truck’s dynamic model. Compared with the theoretical crawl speed, a negative effect of altitude change (from 0 to the altitude above 3000 m) was found on truck’s climbing performance.
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Chapman, Robert F., Trine Karlsen, R. L. Ge, James Stray-Gundersen und Benjamin D. Levine. „Living altitude influences endurance exercise performance change over time at altitude“. Journal of Applied Physiology 120, Nr. 10 (15.05.2016): 1151–58. http://dx.doi.org/10.1152/japplphysiol.00909.2015.
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For sea level based endurance athletes who compete at low and moderate altitudes, adequate time for acclimatization to altitude can mitigate performance declines. We asked whether it is better for the acclimatizing athlete to live at the specific altitude of competition or at a higher altitude, perhaps for an increased rate of physiological adaptation. After 4 wk of supervised sea level training and testing, 48 collegiate distance runners (32 men, 16 women) were randomly assigned to one of four living altitudes (1,780, 2,085, 2,454, or 2,800 m) where they resided for 4 wk. Daily training for all subjects was completed at a common altitude from 1,250 to 3,000 m. Subjects completed 3,000-m performance trials on the track at sea level, 28 and 6 days before departure, and at 1,780 m on days 5, 12, 19, and 26 of the altitude camp. Groups living at 2,454 and 2,800 m had a significantly larger slowing of performance vs. the 1,780-m group on day 5 at altitude. The 1,780-m group showed no significant change in performance across the 26 days at altitude, while the groups living at 2,085, 2,454, and 2,800 m showed improvements in performance from day 5 to day 19 at altitude but no further improvement at day 26. The data suggest that an endurance athlete competing acutely at 1,780 m should live at the altitude of the competition and not higher. Living ∼300-1,000 m higher than the competition altitude, acute altitude performance may be significantly worse and may require up to 19 days of acclimatization to minimize performance decrements.
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Lennertz, Tracy, Andrea L. Sparko, Kim Cardosi, Alan Yost, Andrew Kendra, Jason Lu und Tom Sheridan. „Pilots’ Estimation of Altitude of a Small Unmanned Aircraft System (sUAS)“. Proceedings of the Human Factors and Ergonomics Society Annual Meeting 62, Nr. 1 (September 2018): 49–53. http://dx.doi.org/10.1177/1541931218621011.
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Small unmanned aircraft system (sUAS) operations are growing at a rapid rate, with an increasing number of civilian operations. Currently, the Federal Aviation Administration permits both hobbyist and commercial operations. The requirements for the operations differ; for commercial operations, the sUAS must generally be flown under 400 feet. Past data indicate that operators are poor at judging the altitude of sUAS, and there is variability in the altitude information that is presented to the operator. Here, we examined the ability of commercial and hobbyist sUAS pilots to estimate the altitude of their ownship during a realistic flying task. Participants flew a DJI Phantom 4 Pro to three prescribed altitudes: 50 feet, 200 feet, and 350 feet. In each trial, the participant flew the sUAS from its starting point, hovered at what he or she estimated to be the prescribed altitude, and took a photo of a target. Results indicated that participants’ altitude estimates were below the prescribed altitude of 50 feet 52% of the time, and they were below prescribed altitudes of 200 feet and 350 feet 89% of the time. Despite differences in background, performance did not differ between hobbyist and commercial pilots. Variability in absolute and barometric measurements of altitude was also observed. Taken together, the results suggest that sUAS pilots, regardless of their experience, are poor at judging the altitude of their ownship—especially at higher altitudes. The variability in performance and altitude measurements indicates that pilots need a reliable and standard way to measure the altitude of their ownship, especially given the increasingly complex environments in which sUAS intend to fly.
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., Vibhuti, Kiran Bargali und Surendra Bargali. „Changing pattern of plant species utilization in relation to altitude and their relative prevalence in homegardens of Kumaun Himalaya, India“. Natural Resources for Human Health 2, Nr. 2 (16.01.2022): 253–64. http://dx.doi.org/10.53365/nrfhh/144792.
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The aim of the present study was to analyse the species utilization pattern and their relative prevalence in homegardens varying in size and altitude. Four sites were selected along an altitudinal gradient viz., very low (up to 350 m), low (350-700 m), mid (700-1500 m) and high altitudes (above 2000 m) in Kumaun Himalaya, India. At each altitude, homegardens were categorized into three size classes viz., large (above 0.007 ha), medium (0.004-0.006 ha) and small homegardens (up to 0.003 ha). Maximum species richness was recorded in large sized homegarden at all altitudes except mid altitude where maximum species was observed in medium sized homegardens. Across altitudes, maximum plant species (39) was recorded at mid altitude whereas minimum species (24) were present in high altitude homegardens. Amaryllidaceae was the most important family followed by Oxalidaceae across all the altitudes. In case of plant utilization pattern, maximum species were utilized as a medicine (44.23 %) followed by vegetables (26.66 %), fodder (18.1 %), miscellaneous (15.97 %), spices (13.97 %) and fruits (12.34 %). Among the species, <i>A. cepa</i> (1380) and <i>C. annuum</i> (1026) showed most prevalence whereas <i>S. cumini</i> (278) was the least prevalent species. Across the altitudinal gradient, mid altitude showed most (2341, 1330) relative prevalence whereas high altitude showed least (876, 0) relative prevalence for <i>A. cepa</i> and <i>M. indica</i>, respectively. Management practices and conventional activity could show a higher effect on species composition and their utilization pattern to improve food security and conserving plant genetic diversity in altitudes.
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Blonc, S., N. Fellmann, M. Bedu, G. Falgairette, R. De Jonge, P. Obert, B. Beaune et al. „Effect of altitude and socioeconomic status on VO2max and anaerobic power in prepubertal Bolivian girls“. Journal of Applied Physiology 80, Nr. 6 (01.06.1996): 2002–8. http://dx.doi.org/10.1152/jappl.1996.80.6.2002.
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The aim of this work was to evaluate the effects of high altitude and low socioeconomic status (SES) on aerobic and anaerobic power in 11-yr-old Bolivian girls. At both high (3,600 m) and low (420 m) altitudes, low-SES groups of girls were compared to similarly aged, high-SES girls. At low altitude, low-SES girls were also compared with younger high-SES girls with the same anthropometric characteristics. Anthropometric data were similar between high-SES and low-SES girls at both altitudes, but low-SES girls showed a 9-mo growth delay. Maximal O2 uptake was significantly lower for low-SES girls at both altitudes. Values did not differ when expressed relative to body weight at high altitude for high-SES vs. low-SES girls (37.6 +/- 1.2 vs. 39.3 +/- 1.0 ml.min-1.kg body wt-1), but a difference persisted at low altitude between high- and low-SES girls (37.5 +/- 1.0 vs. 34.7 +/- 0.7 ml.min-1.kg body wt-1). Anaerobic power (Pmax, force-velocity test; Pwing, Wingate test) was reduced for low-SES girls at both altitudes, whatever the mode of expression. For a given SES, the relative anaerobic performances were lower at low altitude. At low altitude, low-SES girls developed lower anaerobic power than did younger high-SES girls with similar anthropometric characteristics. In conclusion, at both altitudes, the reduction of anaerobic performances observed in girls of low SES could not be totally explained by anthropometric factors. Structural and/or functional muscle alterations are suggested. Moreover, at low altitude, tropical and other factors may have contributed to differences in performance between low- and high-SES girls.
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Snyder, L. R. „Low P50 in deer mice native to high altitude“. Journal of Applied Physiology 58, Nr. 1 (01.01.1985): 193–99. http://dx.doi.org/10.1152/jappl.1985.58.1.193.
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Whereas it is widely believed that animals native to high altitude show lower O2 partial pressures at 50% hemoglobin saturation (P50) than do related animals native to low altitude, that “fact” has not been well documented. Consequently, P50 at pH 7.4, PCO2(7.4), the CO2 Bohr effect, and the buffer slope (delta log PCO2/delta pH) were determined via the mixing technique in Peromyscus maniculatus native to a range of altitudes but acclimated to 340 or 3,800 m. PCO2(7.4) and buffer slope were substantially lower at high altitude. The change in P50(7.4) between acclimation altitudes was minimal (0.8% increase at 3,800 m), because of counterbalancing changes in PCO2, 2,3-diphospho-D-glycerate concentration, and perhaps other factors. At both acclimation altitudes there was a highly significant negative correlation between P50(7.4) and native altitude. Since pH in vivo probably increases slightly at high altitude, the data on P50 corrected to pH 7.4 are probably underestimates of the difference in in vivo P50 at low vs. high altitude. Hence these results corroborate theoretical predictions that low P50 is advantageous under severe hypoxic stress.
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Li, Zijun, Junjian Wang, Shuqi Zhao und Yu Xu. „The effect of oxygen supply and oxygen distribution on single-head tunnel with different altitudes under mixed ventilation“. Indoor and Built Environment 31, Nr. 4 (11.01.2022): 972–87. http://dx.doi.org/10.1177/1420326x211051414.
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Hypoxia plays a major role in limiting the construction of the high-altitude mine. Understanding the effect and the distribution of diffused oxygen supply at different altitudes is the premise for the design of a mine with oxygen supply system and the full utilization of oxygen resources. For the optimal design of an oxygen supply mode and ventilation system, a multi-component fluid model of the diffused oxygen supply of a single-head tunnel was developed. This study reveals the variation law of the average oxygen mass fraction at different altitudes. The relationship between the distance from the heading face and the oxygen mass fraction at each altitude was fitted. The results show that the distribution of oxygen mass fraction in a single head tunnel at different altitudes presents a similar trend of increasing first and then decline. In addition, the change of the average oxygen mass fraction with the increase of altitude is not linear, and the dispersion loss is larger in high-altitude areas. The largest oxygen enrichment area is distributed at the altitudes of 4000–4500 m. This study provides theoretical support for improving the hypoxic environment of high-altitude metal mines excavation work.
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Stickford, Abigail S. L., Daniel P. Wilhite und Robert F. Chapman. „No Change in Running Mechanics With Live High—Train Low Altitude Training in Elite Distance Runners“. International Journal of Sports Physiology and Performance 12, Nr. 1 (Januar 2017): 133–36. http://dx.doi.org/10.1123/ijspp.2016-0056.
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Investigations into ventilatory, metabolic, and hematological changes with altitude training have been completed; however, there is a lack of research exploring potential gait-kinematic changes after altitude training, despite a common complaint of athletes being a lack of leg "turnover" on return from altitude training.Purpose:To determine if select kinematic variables changed in a group of elite distance runners after 4 wk of altitude training.Methods:Six elite male distance runners completed a 28-d altitude-training intervention in Flagstaff, AZ (2150 m), following a modified “live high–train low” model, wherein higherintensity runs were performed at lower altitudes (945–1150 m) and low-intensity sessions were completed at higher altitudes (1950–2850 m). Gait parameters were measured 2–9 d before departure to altitude and 1 to 2 d after returning to sea level at running speeds of 300–360 m/min.Results:No differences were found in ground-contact time, swing time, or stride length or frequency after altitude training (P > .05).Conclusions:Running mechanics are not affected by chronic altitude training in elite distance runners. The data suggest that either chronic training at altitude truly has no effect on running mechanics or completing the live high–train low model of altitude training, where higher-velocity workouts are completed at lower elevations, mitigates any negative mechanical adaptations that may be associated with chronic training at slower speeds.
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Eskandar, Mamdoh, Wardah Alasmari, Fawaz Idris, Huda Nadwi, Enshrah Radwan, Tahir Mubarak und Rayan Eskandar. „Impact of Living in Different Altitudes on Intracytoplasmic Sperm Injection (ICSI) Outcomes for Infertile Couples in Southwestern Region of Saudi Arabia, a Retrospective Study“. Obstetrics Gynecology and Reproductive Sciences 6, Nr. 1 (05.01.2022): 01–07. http://dx.doi.org/10.31579/2578-8965/104.
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Objective: The aim of this study was to determine the effect of different altitudes in the Southwestern region of Saudi Arabia on ICSI outcomes, fertilization rate, embryo quality, pregnancy rate, and miscarriage rates for infertile couples. Materials and Methods: This is a retrospective study on 551 infertile couples carried out in the Assisted Reproductive Technology unit at the Maternity and Childern Hospital in Abha, Saudi Arabia between 2018 and 2019 to compare ICSI outcomes in different altitudes. Low altitude (205 patients), mild altitude (86 patients) and high altitude (260 patients). Main result measurements: fertilization rates, embryo quality, clinical pregnancy and miscarriage rates at different altitudes. Results: The data showed that there were no significant differences (P>0.67) in fertilization rates and the number of good-quality embryos between different altitudes. Importantly, clinical pregnancy rates were similar between groups and there was no significant difference in the miscarriage rates between high, mild and low altitudes. Conclusions: This study demonstrates that there is now increased risk of miscarriage or low pregnancy rates with different altitudes in Southwestern region of Saudi Arabia. This suggests that altitude changes has no obvious risk on pregnancy rate and pregnancy outcome.
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Weinstein, Y., M. H. Bernstein, P. E. Bickler, D. V. Gonzales, F. C. Samaniego und M. A. Escobedo. „Blood respiratory properties in pigeons at high altitudes: effects of acclimation“. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 249, Nr. 6 (01.12.1985): R765—R775. http://dx.doi.org/10.1152/ajpregu.1985.249.6.r765.
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Many birds thrive at high altitudes where environmental temperatures are low. Previous studies have shown that tolerance of and acclimation to hypoxia involve cardiopulmonary and hematological adaptations. We investigated blood respiratory properties during exposure to simulated high altitude (hypobaric hypoxia) and low temperature in unanesthetized resting pigeons (Columbia livia, mean mass 0.38 kg). A control group (C) and a group acclimated to 7 km above sea level (ASL) in a hypobaric chamber at 25 degrees C (HA group) were used. All were acutely exposed to altitudes through 9 km ASL at 5 or 25 degrees C. Arterial and mixed venous blood gas tensions and O2 and CO2 content during steady state decreased with increased altitude, whereas blood lactate increased in both groups at both temperatures. Acute high-altitude exposure did not affect hematocrit, hemoglobin concentrations, or O2 carrying capacity, but at any altitude these were all greater in HA than in C birds. At 5 degrees C blood pH increased with altitude in controls but remained unchanged in HA birds. At 25 degrees C in both groups mean intracellular pH did not change, averaging 6.97, whereas extracellular (venous) pH increased with altitude. At the highest altitudes tissue O2 extraction was virtually complete in both groups. Acclimation changed blood O2 and CO2 combining properties in ways likely to improve gas transport at high altitudes. The previously unreported shifts in blood respiratory and acid-base properties with acclimation indicate that innate extrapulmonary adaptations contribute to avian hypoxia tolerance.
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Al-Mosa, Amal, Eid I. Brima, Khaled F. Fawy, Hamed A. AL Ghrama und Mohammed E. A. Mohammed. „Antioxidant Vitamins in Honey Samples from Different Floral Origins and Altitudes in Asir Region at the South-Western Part of Saudi Arabia“. Current Nutrition & Food Science 15, Nr. 3 (25.04.2019): 296–304. http://dx.doi.org/10.2174/1573401314666180606085841.
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Background: Different factors are known to affect the different physiochemical properties of bee's honey including the floral origin and climate. Objective: The aim of this article was to investigate the effect of floral origin and altitude on the concentration of vitamin C and A. Methods: Ten Ziziphus honey samples were collected from two altitudes; 113 and 511 meters. Twenty-five Acacia honey samples were included in this study from five altitudes; 14, 113, 317, 576 and 2247 meters above sea level. Vitamin C was measured by redox titration and vitamin A was estimated using the Carr-price reaction and spectrophotometer. Results: The mean± SD of vitamin C in the Ziziphus and Acacia honey samples were 239.2± 91.5 and 260.4± 81.1 mg\100g, respectively. Vitamin A mean value± SD in the Ziziphus and Acacia honey were 0.088± 0.126 and 0.062± 0.126 mg\ 100g, respectively. Concerning the effect of altitude, there was significant increase in vitamin C concentration in ziziphus honey with the increase of the altitude (p- value= 0.027), while an insignificant decrease was obtained in the case of vitamin A. Regarding the effect of altitude on the concentration of vitamin C in the Acacia honey, there was significant increase in the honey from the altitude of 2247 compared to the honey from all the other altitudes. Vitamin A concentration in the Acacia honey from the altitude 2247 was insignificantly decreased compared to the honey from all the other altitudes (p- value > 0.05). Conclusion: The floral origin insignificantly affected the concentration of vitamin C and A. The altitude significantly affected the concentration of vitamin C irrespective of the floral origin.
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PUTRA, HIRMAS FUADY, DHENOK SEKAR AMBARWATI, NURRIZKI MUBYRASIH und TERSI ALESTI. „Karakteristik Fisiologis Lumut pada Beberapa Ketinggian di Kawasan Gunung Tangkuban Perahu“. Jurnal Sumberdaya Hayati 1, Nr. 2 (04.05.2016): 60–63. http://dx.doi.org/10.29244/jsdh.1.2.60-63.
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Environmental factors greatly influence the physiological state of moss. Some of the environmental factors that influence the physiological of moss are air temperature, humidity, and light intensity. These three environmental factors will vary at each altitude. This study aims to determine the physiological characteristics of mosses on some altitudes in the area of Mount Tangkuban Perahu (Ratu Crater – Domas Crater track). The method that are used is to measure air temperature, humidity, and light intensity at some altitudes. Subsequently, samples were taken at each altitude, to measured chlorophyll and proline content. Mosses that are used as samples; Campylopus sp., Plagiochila sp., Dicranella sp. The results indicate that the chlorophyll content significantly different at some altitude, with an increasing trend as the decrease altitude. The highest chlorophyll content in Campylopus sp. at altitude of 1,621 meters above sea level, while the lowest chlorophyll content in Plagiochila sp. at altitude of 1,721 meters above sea level. The content of proline did not differ significantly at some altitude, and tend to be more affected by air conditions that correlate with distance of moss habitat with the active crater of Domas, which allegedly can cause physiological stress in the moss.
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Wang, Yi, Hongchu Wang, Yinru Chen, Naxin Xu, Winson Lee und Wing-Kai Lam. „Pulmonary Capacity, Blood Composition and Metabolism among Coal Mine Workers in High- and Low-Altitude Aboveground and Underground Workplaces“. International Journal of Environmental Research and Public Health 19, Nr. 14 (07.07.2022): 8295. http://dx.doi.org/10.3390/ijerph19148295.
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(1) Background: While previous studies revealed how underground mining might adversely affect the cardiopulmonary functions of workers, this study further investigated the differences between under- and aboveground mining at both high and low altitudes, which has received little attention in the literature. (2) Methods: Seventy-one healthy male coal mine workers were recruited, who had worked at least 5 years at the mining sites located above the ground at high (>3900 m; n = 19) and low (<120 m; n = 16) altitudes as well as under the ground at high (n = 20) and low (n = 16) altitudes. Participants’ heart rates, pulmonary functions, total energy expenditure and metabolism were measured over a 5-consecutive-day session at health clinics. (3) Results: Combining the results for both above- and underground locations, workers at high-altitude mining sites had significantly higher peak heart rate (HR), minimum average HR and training impulse as well as energy expenditure due to all substances and due to fat than those at low-altitude sites. They also had significantly higher uric acid, total cholesterol, creatine kinase and N-osteocalcin in their blood samples than the workers at low-altitude mining sites. At underground worksites, the participants working at high-altitude had a significantly higher average respiratory rate than those at low-altitude regions. (4) Conclusion: In addition to underground mining, attention should be paid to high-altitude mining as working under a hypoxia condition at such altitude likely presents physiological challenges.
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Abas, Azlan, und Laily Din. „The Diversity of Lichens along Elevational Gradients in the Tropical Montane Forest of Selangor, Malaysia“. Sains Malaysiana 50, Nr. 5 (31.05.2021): 1199–209. http://dx.doi.org/10.17576/jsm-2021-5005-01.
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This study aims to explore how lichen diversity, composition, and distribution vary with altitude, and environmental factors (temperature and relative humidity). The study was conducted in the forest of Gunung Bunga Buah, Selangor at five sites (different altitudes). Forty-four lichen species were identified. Their diversity, composition, and distribution correlated significantly with the altitude and environmental factors, increasing diversity at higher altitudes. Graphidaceae and Physciaceae species were present at all altitudes, and the dominant species changed according to altitude: Some Parmeliaceae species were found only at higher altitudes (601-1430 m) while Chrysothrix xanthina and a few Physciaceae species were present only at lower altitudes (0-600 m). These findings will provide additional information about the lichens of the tropical montane forest of Malaysia to enhance knowledge on how to manage and sustain lichens in this type of forest.
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Stothard, Ellen, Mark Hickey und Christine Ebert-Santos. „0164 Overnight Oximetry in Generationally Un-Adapted Residents of High-Altitude“. Sleep 45, Supplement_1 (25.05.2022): A76. http://dx.doi.org/10.1093/sleep/zsac079.162.
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Abstract Introduction A recent population shift has increased residents of high-altitude locations. Additionally, travel infrastructure has created the opportunity for rapid displacement to high altitudes without adaptation. Residing at high-altitude is a physiological challenge, which increases the risk of overnight hypoxia from sleep disordered breathing. Sleep disordered breathing, including sleep apnea, is a risk factor for a variety of additional negative health outcomes. Additional information is needed to understand the physiology of high-altitude adaptation in generationally un-adapted residents and prevent negative health outcomes. Methods Healthy residents of high altitude participated in this community-supported observational study. Health and altitude history were gathered. Participants completed one night of overnight oxygen monitoring with finger pulse oximetry. Participants with BMI >30 kg/m2, sleep time <4 or >10 hours were excluded. Results Total of 41 participants included, 68.3% female, 44.9±13.0 years (SD), BMI 23.7±2.5 kg/m2. Participants resided at altitudes between 2500–3048 m. Participants were also characterized by their years at altitude and percent of life spent at altitude, average 15.9±12.2 years (median 13) and average 33.0±21.7% of life at altitude. Neither years or percent of life at altitude were predicted percent of time below 88% O2 on overnight pulse oximetry (R2 = 0.04 and 0.03, both p>0.12). Multiple Linear Regression indicated BMI was the only factor that explained a signification portion of the variance in adaptation (p<0.01). Conclusion In a generationally un-adapted population of high-altitude residents, years at altitude and percent of life at altitude do not explain the variance of adaptation to altitude as measured by percent of night spent hypoxic with less than 88% SpO2. While these data do not provide support for an adaptation response based on time at altitude, they indicate future directions in human altitude adaptation should focus on other covariates, potentially including genetic differences. Support (If Any)
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Shrestha, Sabina, Aparajita Manoranjan und Sushan Man Shrestha. „Oxygen saturation at different altitudes in Nepal among adults“. Grande Medical Journal 2, Nr. 1 (28.12.2020): 19–21. http://dx.doi.org/10.3126/gmj.v2i1.45674.
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Introduction: The partial pressure of oxygen in the atmosphere decreases proportionately with an increase in the altitude. The study was done to compare the oxygen saturation of non-acclimatized adults going to different altitudes in Nepal. Materials and Methods: It was a descriptive observational study conducted on ten individuals of a medical team traveling to Humla district of Nepal for a multi-disciplinary medical camp. Oxygen saturation was measured at different altitudes i.e. in Kathmandu, Nepalgunj, in the flight at an altitude of 3360 meters and in Bargaun village of Humla district located at an altitude of 3300 meters. Mean pulse oximetry reading was calculated and compared. Results: Among the participants, age ranged from 24-57 years. Male to female ratio was 1.5:1. The mean SPO2 at Nepalgunj, Kathmandu, Bargaun of Humla and in the flight (at an altitude of 3360 meters) were 99.67 %, 97%, 91% and 87.4% respectively among the study participants. However, the difference in Oxygen saturation values at different altitudes among different gender and different age was not statistically significant. Conclusions: Oxygen saturation decreased linearly with the rise in altitude among all the study participants irrespective of age and gender.
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Suchý, Jiří, Jiří Novotný und Pavel Tilinger. „Porovnání vlivu hyperoxie na krátkodobý anaerobní výkon v nížině a vyšší nadmořské výšce“. Studia sportiva 4, Nr. 1 (07.07.2010): 17–23. http://dx.doi.org/10.5817/sts2010-1-3.
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The article compares the infl uence of inhaling concentrated oxygen on short-term repeated performance in lowlands and at high altitudes above sea level (1 835 m a.s.l.). Th e source of concentrated oxygen was Oxyfi t. Th e subjects (n=10) completed a total of four tests comprised of two Wingate tests at a 10 minute interval. Two tests were carried out at a low altitude and two at a higher altitude above sea level. During the recovery period between tests the monitored subjects inhaled Oxyfi t or a placebo (at both the low and high altitudes). Th e study showed signifi cantly (p < 0.05) higher performance of the repeated Wingate test aft er inhaling concentrated oxygen in comparison with the placebo at both low and higher altitudes. Inhalation of concentrated oxygen aff ects performance to a greater extent at the higher altitude compared to that of the low altitude.
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Subedi, Dharma Datta, Muza Shrestha, Biyush Pokharel, Prabodh Regmi und Jay Narayan Shah. „Endoscopic findings of acid peptic disease at low and high altitude: Kathmandu versus Rasuwa districts of Nepal“. Journal of Patan Academy of Health Sciences 9, Nr. 2 (30.08.2022): 49–54. http://dx.doi.org/10.3126/jpahs.v9i2.48082.
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Introduction: Features of Acid Peptic Disease (APD) have specific presentations from low to high altitudes. This study aims to compare the endoscopy findings of APD at low altitudes (Kathmandu Valley) and High Altitudes (Rasuwa District) of Nepal.
Method: Endoscopy findings of APD patients from Nov 2017 to Dec 2021 at Manmohan Medical College and Teaching Hospital (MMTH) were reviewed from the data kept in the endoscopy unit to compare the findings in patients from low altitudes (Kathmandu valley) and high altitudes (Rasuwa district). Variables included were age, sex, and endoscopy findings of APD. Microsoft Excel was used for data analysis. Chi-square analysis was used for the association between APD findings and altitude. A p-value ≤0.05 was considered statistically significant.
Result: Out of 2937 APD patients, 1560 (53.1%) were male and 1377(46.9%) female, age 48.5 years (range 16-81) with 2701(91.6%) having endoscopic findings of APD. Among 2701 APDs, 1448 (88.6%) were from the low altitude of Kathmandu valley, and 1253 (96.2%) from high altitude (Rasuwa district), p-value <0.0002. There were 736(50.8%) patients with gastritis from Kathmandu vs. 695 (55.46%) from Rasuwa, followed by gastro-duodenitis 219(15.1%) vs. 32 (2.5%), duodenitis 171 (11.8%) vs. 169(13.5%) respectively.
Conclusion: The incidence of endoscopic findings of overall APD was high among patients from the high altitude of Rasuwa district compared to the low altitude Kathmandu valley of Nepal.
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Ghelichnia, H. „Essential Oil Composition of Thymus fedtschenkoi Ronniger at Different Growing Altitudes in Mazandaran, Iran“. Cercetari Agronomice in Moldova 51, Nr. 2 (01.06.2018): 75–83. http://dx.doi.org/10.2478/cerce-2018-0018.
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Abstract Thymus fedtschenkoi Ronniger (Lamiaceae) is a permanent, that grows in some mountain rangelands of Iran, including Mazandaran province. The aerial parts of Thymus fedtschenkoi were collected during flowering stage in June 2012, from mountain rangelands of Mazandaran province, in north of Iran. Samples were collected from five altitudes (1300 m, 1600 m, 2000 m, 2400 m and 3000 m) in mountain region of Mazandaran province. The goal of current research was to assessment the effect of altitude on the chemical composition and function of essential oil in Thymus fedtschenkoi. The essential oil were obtained by hydrodistillation and analyzed by gas chromatography (GC) and gas spectrometry (GC-MS). Based on the results, the essential oil content is between 0.92-1.31%, at different altitudes. The highest content of essential oil (1.31%%) was extracted in the highest altitude (3000 m), while it was opposite (0.92%) in the lowest altitude (1300 m). The main essential oil compounds of Thymus fedtschenkoi samples were thymol (8.62%-36.86%), carvacrol (6.787%-68.39%), γ-terpinene (1.473T-6.461%), p-cymen (5.764%-16.204%) and linalool (0.465%-6.457 6.8%). According to the results, altitude has a positive effect on the percentage of essential oils and essential oil increases with increasing altitude. The altitude has a negative effect on the percentage of thymol and the content of thymol decreased with increasing altitude. The altitude has a positive effect on the percentage of carvacrol and the content of carvacrol increased with increasing altitude.
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Khan, Inam Danish. „Knowledge, Attitude and Practices Regarding Extreme Environments and Cold Adaptation at Extreme Altitudes on the Himalayan Ranges“. International Journal of Travel Medicine and Global Health 8, Nr. 1 (05.03.2020): 18–21. http://dx.doi.org/10.34172/ijtmgh.2020.03.
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Introduction: Extreme-altitudes (5500 m/18045 ft and higher) pose environmental, psychophysiological, infrastructural, logistic, and ergonomic challenges that question explorer’s adaptability and mission-efficiency due to isolation, monotony, intimidating environment and terse health conditions. The assessment of an explorer’s comprehensive adaptability in extreme-altitudes is of paramount importance in ensuring mission-preparedness. Knowledge, attitude, and practices (KAP) of explorers staying on extreme-altitudes was assessed through personal interview technique. Methods: 125 healthy, acclimatized, mountain-trained explorers staying above 4570 m/15000 ft in winter-season for at least 30 days on extreme-altitudes were assessed by a single cross-sectional study through personal interviews on KAP related to extreme-altitude and cold-adaptation. Results: Mean duration of stay on extreme-altitude was 55.7 days. All explorers knew about difficulties and health-problems at extremealtitude. All explorers felt that mountain-training and acclimatization were beneficial. 92% felt that mission tenure of 90 days on the extreme-altitude was adequate. 92.8% felt they were adequately trained for the extreme-altitude; however, only 52% felt confident about health-training. 66.4% did preventive rewarming of extremities. 66.4% regularly smoked/chewed tobacco. 57.6% had sleep problems and 64% had altered appetite. 26.4% felt difficulties related to living conditions, infrastructure, and logistics. Conclusion: Explorers at extreme-altitude exhibited adequate knowledge and performed activities with progressive attitude and healthy practices. Explorers endured altered psychophysiology at extreme-altitude and regarded the utility of training and acclimatization programs. Knowledge-practice gap existed towards tobacco consumption. There was a felt need for the improvement of living conditions, infrastructure, logistics, and health-related training.
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Jiao, Jun, Bifeng Song, Yubin Li, Yugang Zhang und Jianhua Xu. „Development of a testing methodology for high-altitude propeller“. Aircraft Engineering and Aerospace Technology 90, Nr. 9 (14.11.2018): 1486–94. http://dx.doi.org/10.1108/aeat-02-2017-0069.
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Purpose The purpose of this paper is to develop a propeller performance measurement method for high-altitude platforms by analyzing of the propeller aerodynamic characteristics and application of a mobile testing system. Design/methodology/approach An experimental approach is adopted for this study. Considering the aerodynamic characteristics of the high-altitude propeller, the similitude of the scaled propeller model in the experiment is analyzed and determined. Then, the experimental method and procedure to obtain the propeller’s performance under different altitudes are presented, and the structure of hardware and software and the key techniques of the testing system are introduced in detail. Findings The applicability and effectiveness of the testing system is verified through comparison between experimental and numerical results. In addition, the performance of the 6.8-m propeller for a high-altitude airship is tested, which proves that the high-altitude propeller can meet the requirements of the propulsion system. Practical implications The testing methodology and the mobile testing system could be applied to aerodynamic performance evaluation of the high-altitude propellers under different altitudes. Originality/value This testing approach exhibits significant time and cost benefits over many other experimental methods to obtain the performance of the high-altitude propellers, which is important in the preliminary design of the propulsion system for high-altitude platforms.
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Wagenhäuser, Thomas, Andreas Engel und Robert Sitals. „Testing the altitude attribution and vertical resolution of AirCore measurements with a new spiking method“. Atmospheric Measurement Techniques 14, Nr. 5 (27.05.2021): 3923–34. http://dx.doi.org/10.5194/amt-14-3923-2021.
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Abstract. AirCore samplers have been increasingly used to capture vertical profiles of trace gases reaching from the ground up to about 30 km, in order to validate remote sensing instruments and to investigate transport processes in the stratosphere. When deployed to a weather balloon, accurately attributing the trace gas measurements to the sampling altitudes is nontrivial, especially in the stratosphere. In this paper we present the CO-spiking experiment, which can be deployed to any AirCore on any platform in order to evaluate different computational altitude attribution processes and to experimentally derive the vertical resolution of the profile by injecting small volumes of signal gas at predefined GPS altitudes during sampling. We performed two CO-spiking flights with an AirCore from the Goethe University Frankfurt (GUF) deployed to a weather balloon in Traînou, France, in June 2019. The altitude retrieval based on an instantaneous pressure equilibrium assumption slightly overestimates the sampling altitudes, especially at the top of the profiles. For these two flights our altitude attribution is accurate within 250 m below 20 km. Above 20 km the positive bias becomes larger and reaches up to 1.2 km at 27 km altitude. Differences in descent velocities are shown to have a major impact on the altitude attribution bias. We parameterize the time lag between the theoretically attributed altitude and the actual CO-spike release altitude for both flights together and use it to empirically correct our AirCore altitude retrieval. Regarding the corrected profiles, the altitude attribution is accurate within ±120 m throughout the profile. Further investigations are needed in order to test for the scope of validity of this correction parameter regarding different ambient conditions and maximum flight altitudes. We derive the vertical resolution from the CO spikes of both flights and compare it to the modeled vertical resolution. The modeled vertical resolution is too optimistic compared to the experimentally derived resolution throughout the profile, albeit agreeing within 220 m. All our findings derived from the two CO-spiking flights are strictly bound to the GUF AirCore dimensions. The newly introduced CO-spiking experiment can be used to test different combinations of AirCore configurations and platforms in future studies.
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Nepal, O., BR Pokharel, K. Khanal, P. Gyawali, SL Malik, R. Koju und BK Kapoor. „Thyroid Hormone levels in Highlanders- A Comparison Between Residents of Two Altitudes in Nepal“. Kathmandu University Medical Journal 11, Nr. 1 (09.09.2014): 18–21. http://dx.doi.org/10.3126/kumj.v11i1.11017.
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Background The endocrine changes related to altitude adaptation in human have attracted physiologists around the globe for long. A number of high altitude studies to detect the physiological changes have been performed now and then. But, the study to see the hormonal changes to compare populations residing at different high altitudes is a scarce. Hence, we have performed a study in native populations of different high altitude comparing changes in thyroid hormones in western Nepal. The Jharkot population included in this study is at altitude of 3760m and Jomsom population at 2800m height from sea bed. Objective The study is to compare changes in thyroid hormones at two different high altitude natives. Methods To compare thyroid status between high altitude natives at two different altitudes a cross sectional study is performed by random sampling method. The blood sample was collected in a vacutainer from fifty eight individuals after obtaining the informed consent of participants. The blood collected from antecubital vein was centrifuged in an hour and the serum obtained was used for biochemical analysis of free triiodothyronine, free thyroxine and thyroid stimulating hormone. Results Mean free thyroxine (fT4) of Jharkot population is significantly larger (p = 0.001) than Jomsom population. Mean thyroid stimulating hormone (TSH) with p = 0.597, does not indicate the difference between this two population. There is no significant difference between mean free triiodothyronine (fT3) of Jharkot and Jomsom population (p = 0.345). Conclusion The rise in free thyroid hormone at high altitude is not dependent on the thyroid stimulating hormone released from anterior pituitary. The rise in free thyroxine is found at higher altitude and no difference in fT3 level is detected in population studied at high altitudes. DOI: http://dx.doi.org/10.3126/kumj.v11i1.11017 Kathmandu University Medical Journal Vol.11(1) 2013: 18-21
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Han, Kaiyue, Xiaoling Su, Jiang Liu, Fengcai Yao und FeiYan Lu. „Red Cell Distribution Width as a Novel Marker for Different Types of Atrial Fibrillation in Low and High Altitude“. Cardiology Research and Practice 2019 (07.03.2019): 1–8. http://dx.doi.org/10.1155/2019/6291964.
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Background. Increased red cell distribution width (RDW) can predict the incidence and mortality of cardiovascular diseases. However, there are limited data on the relationship between RDW and altitude and the subtype of atrial fibrillation (AF). We investigated the effects of altitude on RDW in patients with different types of AF. Methods. A total of 303 patients with nonvalvular AF were included. Of these, 156 lived in low altitude (77 paroxysmal AF, PAF; 79 persistent AF, PeAF) and 147 in high altitude (77 paroxysmal AF, PAF; 70 persistent AF, PeAF). In these groups, baseline characteristics, complete blood counts, serum biochemistry, and echocardiography were evaluated. Multivariate logistic regression analysis was conducted to determine the independent predictors of AF at the different altitudes. Results. In both low and high altitudes, RDW and left atrial diameter (LAD) were higher in AF than control subjects (P<0.05) and higher in persistent AF than paroxysmal AF (P<0.05). Compared with any groups (PAF group, PeAF group, or control group) of low-altitude, RDW and LAD were found higher in high-altitude corresponding groups. Multivariate logistic regression analysis demonstrated that RDW, mean corpuscular volume (MCV), and LAD levels independently associated with AF patients in low altitude (RDW, OR 1.687, 95% CI 1.021–2.789; P<0.05), while in high altitude, RDW, MCV, creatinine (Cr), and LAD were independent predictors for AF patients (RDW, OR 1.755, 95% CI 1.179–2.613; P<0.05). Conclusion. Elevated RDW levels may be an independent risk marker for nonvalvular AF, affected by type of AF and altitude.
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Lestari, M.Env., Ratri Yuli, Dwi Harsono und Nazarni Rahmi. „The Characteristics of Bamboo Charcoal Derived from Bambusa vulgaris Schrad and Arundinaria gigantea (Walter) Muhl Growing in Different Types of Habitats“. Jurnal Riset Industri Hasil Hutan 10, Nr. 1 (27.12.2018): 1–10. http://dx.doi.org/10.24111/jrihh.v10i1.3889.
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Altitude is one of the factors that affect the growth of bamboo. Bamboo species used in this study was Bambusa vulgaris and Arundinaria gigantea. The objectives of this study are to investigate the effect of altitude to the characteristics of bamboo charcoal harvested from three different altitudes (Lumpangi, Banjarbaru/Martapura, Marabahan). Parameters tested in this study were moisture content, ash content, volatile matter, fixed carbon and calorific value. The result showed that altitute significantly affected the characteristics of bamboo charcoal. Bamboo charcoal from Banjarbaru/Martapura had the best characteristics than the charcoal produced from other locations. The moisture content, ash content, volatile matter, fixed carbon and calorific value of B. vulgaris were 0.77 %; 3.49 %; 8.63 %; 87.11 % and 7,331.05 kal/g. The moisture content, ash content, volatile matter, fixed carbon and calorific value of A. gigantea were 0.19 %; 12.46 %; 4.48 %; 87.11 % and 6,640.69 kal/g, respectively.
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Vidojević, Dragana, Maja Manojlović, Aleksandar Đorđević, Radovan Savić, Ljiljana Nešić und Božidar Đokić. „Soil organic carbon stocks in relation to the altitude in Serbia“. Zemljiste i biljka 70, Nr. 1 (2021): 102–16. http://dx.doi.org/10.5937/zembilj2101102v.
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The research was conducted to determine the soil organic carbon (SOC) stocks in relation to the altitude in Serbia. The database included a total of 1,140 soil profiles. SOC were investigated at different the altitudes (0-200 m, 200-500 m, 500-1,000 m, 1,000 - 2.000 m) and at two soil depths (0-30 cm and 0-100 cm). Statistical correlation was done for five regions where locations were grouped according to the spatial distribution. The results showed that the highest mean values of SOC were measured on the terrain that includes mountains with the altitudes of 1,000-2,000 m and covers an area of 11.5% of the territory of Serbia. The lowest obtained result is related to the lowland areas with the largest number of locations. Greater variability in the results of SOC stocks were found at the higher altitudes and the greatest on the low mountains of 500-1,000 m altitude. There is a medium to strong statistical dependence of the altitude with the SOC stocks at two soil depths (0-30 cm and 0-100 cm). The result indicate that the relationship between SOC stocks and altitude varies between the regions. This study shows that altitude is an important factor affecting SOC stocks.
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Spring, Allison M., Kenneth D. Domingue, Thomas V. Kerber, Margaret M. Mooney, Rebecca L. Hale, Kristina M. Lemmer und Kathryn M. Docherty. „Land Use Effects on Airborne Bacterial Communities Are Evident in Both Near-Surface and Higher-Altitude Air“. Diversity 13, Nr. 2 (18.02.2021): 85. http://dx.doi.org/10.3390/d13020085.
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Land use influences the composition of near-surface airborne bacterial communities, and bacteria can be transported through the atmosphere at global scales. The atmosphere mixes vertically, but rigorously assessing whether the effects of land use on atmospheric communities extends to higher altitudes requires examining communities from multiple altitudes collected at a stable location and timeframe. In this study, we collected near-surface (<2 m) and higher-altitude (150 m) air samples from three sites in an agricultural/developed location and a forested/undeveloped location. We used bacterial 16S rRNA amplicon sequencing to compare communities and predict functionality by altitude. Higher-altitude and near-surface communities did not differ in composition within each location. Communities collected above the undeveloped location were equally variable at both altitudes; higher-altitude samples from the developed location predominantly contained Firmicutes and were less variable than near-surface samples. We also compared airborne taxa to those present in soil and snow. Communities from higher-altitude samples above the developed location contained fewer overlapping taxa with soil and snow sources, and overlapping Operational Taxonomic Units (OTUs) among the three sources differed by location. Our results suggest that land use affects the composition of both near-surface and higher-altitude airborne bacterial communities and, therefore, may influence broad bacterial dispersal patterns. This small-scale pilot study provides a framework for simultaneously examining local and regional airborne microbial communities that can be applied to larger studies or studies using different types of samplers.
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HALL, J. W., D. G. STOUT und B. BROOKE. „EFFECT OF SEED SOURCE ON GROWTH OF GIANT WILDRYE (Elymus cinereus) AT TWO ELEVATIONS IN INTERIOR BRITISH COLUMBIA“. Canadian Journal of Plant Science 70, Nr. 2 (01.04.1990): 551–54. http://dx.doi.org/10.4141/cjps90-068.
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Giant wildrye (Elymus cinereus Scribn. & Merr.) plants grown from seed obtained at two altitudes (346, 930 m) were transplanted to two sites (346, 900 m) and observed for 3 yr. Plants from the low altitude source produced more dry matter at both sites. More plants from the low altitude source produced seed heads at the low altitude site but seed head production of plants from the two sources was similar at the high altitude site. Provided studies of germination, seedling establishment and initial growth at different elevations were favorable, seed from low altitude sources could be used indiscriminately for establishing stands of giant wildrye. This would greatly simplify the use of giant wildrye as a forage crop in areas where varying altitude was of concern.Key words: Elymus cinereus, altitude adaptation, growth forms, reciprocal transplants, ecotypes
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Cejnar, Jan, und Iveta Kameníková. „Temperature Effect to Altitude Corrections and Operational Application“. MAD - Magazine of Aviation Development 8, Nr. 1 (29.03.2020): 18–22. http://dx.doi.org/10.14311/mad.2020.01.02.
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The thesis is focused to familiarize the reader with air mass behaviour, legislative requirements and methods of altitude corrections. The goal of the thesis is evaluation of the presently used operational procedures applied to the altitude corrections according to the change of air parameters. The final part of the thesis determines altitudes necessary for corrections and represents the proposal of optimized altitude correction method.
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Haider, Flora, Narendra Kumar, Ali Arif Naqvi und Guru Das Bagchi. „Oil Constituents of Artemisia nilagirica var. septentrionalis Growing at Different Altitudes“. Natural Product Communications 5, Nr. 12 (Dezember 2010): 1934578X1000501. http://dx.doi.org/10.1177/1934578x1000501227.
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Oils of Artemisia nilagirica var. septentrionalis plants growing at different altitudes in Himachal Pradesh, India were hydrodistilled and analyzed by GC-GC/MS. The major constituents of the oil show variation with changes in altitude. At lower, middle and higher altitudes, the major constituents of the oil were caryophyllene oxide (28.6%), borneol (35.8%) and camphor (46.9%), respectively. The percentages of α-humulene and trans-β-guaiene also increased, but the percentage of sabinene, trans-sabinene hydrate, 4-terpineol, caryophyllene oxide and humulene epoxide-II decreased with an increase in altitude. The characteristic compounds observed in the plants from lower altitudes were 2-hexene-1-ol, β-thujone, thujanol, myrtenol and linalyl acetate, while the higher altitude plants were characterized by the presence of α-pinene, β-pinene, limonene, linalool, γ-gurijunene, germacrene-D and farnesol.
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Bayer, Roman G. „Altitude illness“. Disaster Prevention and Management: An International Journal 26, Nr. 1 (06.02.2017): 55–64. http://dx.doi.org/10.1108/dpm-07-2016-0146.
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Purpose Altitude illness can be a severe to even life-threatening condition for individuals ascending to altitudes higher than 2,500 m without proper acclimatization, a process that requires at least a couple of days. Considering disaster scenarios in high-altitude settings where humanitarian aid workers need to be deployed immediately, altitude illness may pose a relevant risk factor. The paper aims to discuss these issues. Design/methodology/approach Population data on people living in high-altitude risk areas worldwide were matched with data on natural hazards in these areas. Findings Globally, more than 140 million people live in the risk zone for altitude illness and at least 19 cities with a population of more than 100,000 people exist above 2,500 m. These cities are situated in countries that are highly vulnerable to various natural hazards, and most of these cities have already been affected by hazardous events in the past. The relevance of considering altitude illness is underlined by a report on the emergency operation after the 2010 earthquake in Yushu County, China, where at least 200 aid workers had to be withdrawn due to this condition. Originality/value There are possible disaster scenarios where altitude illness can become a serious issue for aid workers, however, the only available preventive measures are not feasible with proper acclimatization requiring a couple of days and chemoprophylaxis not being 100 percent efficient. Therefore, this work intends to raise awareness within the humanitarian community for and to proactively engage with the topic of altitude illness in order to ensure the security and well-being of staff.
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Sha, Yuzhu, Yue Ren, Shengguo Zhao, Yanyu He, Xinyu Guo, Xiaoning Pu, Wenhao Li, Xiu Liu, Jiqing Wang und Shaobin Li. „Response of Ruminal Microbiota–Host Gene Interaction to High-Altitude Environments in Tibetan Sheep“. International Journal of Molecular Sciences 23, Nr. 20 (17.10.2022): 12430. http://dx.doi.org/10.3390/ijms232012430.
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Altitude is the main external environmental pressure affecting the production performance of Tibetan sheep, and the adaptive evolution of many years has formed a certain response mechanism. However, there are few reports on the response of ruminal microbiota and host genomes of Tibetan sheep to high-altitude environments. Here, we conducted an integrated analysis of volatile fatty acids (VFAs), microbial diversity (16S rRNA), epithelial morphology, and epithelial transcriptome in the rumen of Tibetan sheep at different altitudes to understand the changes in ruminal microbiota–host interaction in response to high altitude. The differences in the nutritional quality of forage at different altitudes, especially the differences in fiber content (ADF/NDF), led to changes in rumen VFAs of Tibetan sheep, in which the A/P value (acetic acid/propionic acid) was significantly decreased (p < 0.05). In addition, the concentrations of IgA and IgG in Middle-altitude (MA) and High-altitude Tibetan sheep (HA) were significantly increased (p < 0.05), while the concentrations of IgM were significantly increased in MA (p < 0.05). Morphological results showed that the width of the rumen papilla and the thickness of the basal layer increased significantly in HA Tibetan sheep (p < 0.05). The 16S rRNA analysis found that the rumen microbial diversity of Tibetan sheep gradually decreased with increasing altitude, and there were some differences in phylum- and genus-level microbes at the three altitudes. RDA analysis found that the abundance of the Rikenellaceae RC9 gut group and the Ruminococcaceae NK4A214 group increased with altitudes. Furthermore, a functional analysis of the KEGG microbial database found the “lipid metabolism” function of HA Tibetan sheep to be significantly enriched. WGCNA revealed that five gene modules were enriched in “energy production and conversion”, “lipid transport and metabolism”, and “defense mechanisms”, and cooperated with microbiota to regulate rumen fermentation and epithelial immune barrier function, so as to improve the metabolism and immune level of Tibetan sheep at high altitude.
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White, Margueritte Mabry, Robert E. McCullough, Rebecca Dyckes, Alastair D. Robertson und Lorna G. Moore. „Effects of pregnancy and chronic hypoxia on contractile responsiveness to α1-adrenergic stimulation“. Journal of Applied Physiology 85, Nr. 6 (01.12.1998): 2322–29. http://dx.doi.org/10.1152/jappl.1998.85.6.2322.
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Decreased contractile response to vasoconstrictors in uterine and nonuterine vessels contributes to increased blood flow to the uterine circulation during normal pregnancy. Pregnancies complicated by preeclampsia and/or chronic hypoxia show a reversal or diminution of these pregnancy-associated changes. We sought to determine whether chronic hypoxia opposes the reduction in contractile response in uterine and nonuterine vessels during normal pregnancy and, if so, whether decreased basal nitric oxide (NO) activity was involved. We examined the contractile response to phenylephrine (PE) in guinea pig uterine artery (UA), mesenteric artery (MA), and thoracic aorta (TA) rings isolated from nonpregnant or pregnant guinea pigs that had been exposed throughout gestation to either low (1,600 m, n = 47) or high (3,962 m, n = 43) altitude. In the UA, pregnancy reduced contractile sensitivity to PE and did so similarly at low and high altitude (EC50: 4.0 × 10−8 nonpregnant, 9.3 × 10−8 pregnant at low altitude; 4.8 × 10−8nonpregnant, 1.0 ×10−8pregnant at high altitude; both P < 0.05). Addition of the NO synthase inhibitor nitro-l-arginine (NLA; 200 mM) to the vessel bath increased contractile sensitivity in the pregnant UA ( P < 0.05) and eliminated the effect of pregnancy at both altitutes. NLA also raised contractile sensitivity in the nonpregnant high-altitude UA, but contractile response without NLA did not differ in the high- and low-altitude animals. In the MA, pregnancy decreased contractile sensitivity to PE at high altitude only, and this shift was reversed by NO inhibition. In the TA, neither pregnancy nor altitude affected contractile response, but NO inhibition raised contractile response in nonpregnant and pregnant TA at both altitudes. We concluded that pregnancy diminished contractile response to PE in the UA, likely as a result of increased NO activity, and that these changes were similar at low and high altitude. Counter to our hypothesis, chronic hypoxia did not diminish the pregnancy-associated reduction in contractile sensitivity to PE or inhibit basal NO activity in the UA; rather it enhanced, not diminished, basal NO activity in the nonpregnant UA and the pregnant MA.
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Kingston, Cath. „Can altitudinal diversity gradients be explained by a reduction in area with altitude?“ Pacific Conservation Biology 8, Nr. 3 (2002): 211. http://dx.doi.org/10.1071/pc020211.
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Species richness at higher altitudes of a region typically decreases with altitude, the usual explanation being that environmental conditions become harsher as altitude increases. On conical or ridge shaped mountains the surface area available within equally spaced altitude bands declines as altitude increases. It has been suggested (Ogden 1995) that this may be responsible for the decrease in species richness. The phenomenon of decreasing species richness with altitude has been further interpreted by Ogden as lending support to the equilibrium theory of island biogeography (MacArthur and Wilson 1967) which predicts that larger areas will contain more species. The hypothesis that a decrease in area is responsible for the decline in diversity with altitude is here considered critically, and the evidence presented in support of it is found to be lacking.
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Kan, Ze-chao, Zhi-yuan Hu, Di-ming Lou, Zhi-yi Cao und Jie Cao. „Effect of the altitude on the combustion characteristics of a low-compression-ratio diesel engine during the start-up process“. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 231, Nr. 13 (20.12.2016): 1838–47. http://dx.doi.org/10.1177/0954407016679443.
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One of the ways to meet future emission standards for cars and to limit the peak pressure of a heavy-duty, highly supercharged diesel engine is to reduce the compression ratio. Nevertheless, complications appear because stringent limitations to a reduction in the diesel compression ratio are the start-up requirements, in particular at high altitudes. An experimental study was conducted on the effect of the altitude on the combustion characteristics during the start-up process of a direct-injection midspeed intercooled turbocharged diesel engine with a compression ratio of 14.25:1. Specialized testing was conducted on the low-compression-ratio diesel engine, the intake pressure and the exhaust pressure of which were controlled by a plateau simulation test system to simulate the conditions at altitudes of 0 m, 1000 m, 2000 m, 3000 m, 3750 m and 4500 m. The results indicated that the pressure in the cylinder was lower during the cranking period as the altitude increased and that this caused the ignition operation to become difficult at altitudes above 3000 m. The combustion characteristics are significantly impacted by altitudes above 2000 m. At an altitude of 0–1000 m, the curve pattern of the cycle cylinder pressure had mainly a single peak during the start-up period. When the altitude increased to 2000 m, twin peaks and afterburn appeared in the cycles. Misfire appeared during the start-up period when the altitude increased to 3000 m, the combustion instability increased and the average indicated mean effective pressure decreased rapidly. When the altitude increases, the cycle-to-cycle variations in the peak pressure increased during idle, the ignition and the crank angle position at 50% of the cumulative heat release rate were delayed and the combustion duration was extended.
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Rosemary Kinge, Tonjock, Nkengmo Apiseh Apalah, Theobald Mue Nji, Ache Neh Acha und Afui Mathias Mih. „Species Richness and Traditional Knowledge of Macrofungi (Mushrooms) in the Awing Forest Reserve and Communities, Northwest Region, Cameroon“. Journal of Mycology 2017 (06.06.2017): 1–9. http://dx.doi.org/10.1155/2017/2809239.
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Macrofungi are diverse in their uses as food and medicine and several species serve as decomposers and also form mycorrhizal associations. Awing forest reserve is diverse in plants and fungi species. However, no work has been carried out to assess the diversity and traditional knowledge of macrofungi in the area. Diversity surveys were carried out in three altitudes using transects of 50×20 m for six months in 2015. Ethnomycology studies were carried out in fifteen communities using focus group discussion, pictorial presentation, and questionnaires. The data was analyzed using descriptive statistics in Microsoft Excel 2010. Seventy-five species belonging to thirty families were identified by morphology. Thirty-six species were found only in the low altitude, 16 in the mid altitude, and 16 species in high altitude. One species was common to low and mid altitude and also low and high altitude; five species were common to mid and high altitude while there was no species common to all three altitudes. The indigenes of the Awing communities commonly called mushroom “Poh” and use it mainly as food and medicine and in mythological beliefs. The most utilized species as food and medicine included Termitomyces titanicus, Laetiporus sulphureus, and Ganoderma sp.
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Shrestha, S., S. Shrestha, L. Shrestha und N. Bhandary. „Oxygen Saturation of Hemoglobin in Healthy Children of 2- 14 Years at High Altitude in Nepal“. Kathmandu University Medical Journal 10, Nr. 1 (02.10.2012): 30–33. http://dx.doi.org/10.3126/kumj.v10i1.6912.
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Background Individuals residing at higher altitude may have oxygen saturation of hemoglobin different to those living at lower altitude. # Objectives To find out the baseline value of SpO2 in healthy Nepali children (2-14 years) living permanently at high altitude using pulse oximeter and also to study the relation of SpO2 with age, sex and ethnicity. Methods A descriptive observational study was conducted at 4 different altitudes ranging from 2700 to 3800 m in Mustang district. The mean pulse oximery values at different altitudes were calculated and compared. Results One hundred six children were enrolled with the median age of 10 years. The mean SpO2 value of children permanently residing at altitude 2700m was 95.18%, at 2800m was 94.82%, at 3550m was 94.1% and 3800m was 93.1%.The difference in the SpO2 values at different altitude was statistically significant. No sex or age wise differences were noted on the mean SpO2 values in the study group. Conclusions The mean SpO2 values were higher than several other studies done in the altitude above 2500 meters. Enrollment of older children and the different ethnic background could be the contributing factors for the differences. KATHMANDU UNIVERSITY MEDICAL JOURNAL VOL.10 | NO. 1 | ISSUE 37 | JAN - MAR 2012 | 40-43 DOI: http://dx.doi.org/10.3126/kumj.v10i1.6912
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Viscor, Ginés, Jordi Corominas und Anna Carceller. „Nutrition and Hydration for High-Altitude Alpinism: A Narrative Review“. International Journal of Environmental Research and Public Health 20, Nr. 4 (11.02.2023): 3186. http://dx.doi.org/10.3390/ijerph20043186.
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This report aims to summarise the scientific knowledge around hydration, nutrition, and metabolism at high altitudes and to transfer it into the practical context of extreme altitude alpinism, which, as far as we know, has never been considered before in the literature. Maintaining energy balance during alpine expeditions is difficult for several reasons and requires a deep understanding of human physiology and the biological basis for altitude acclimation. However, in these harsh conditions it is difficult to reconcile our current scientific knowledge in sports nutrition or even for mountaineering to high-altitude alpinism: extreme hypoxia, cold, and the logistical difficulties intrinsic to these kinds of expeditions are not considered in the current literature. Requirements for the different stages of an expedition vary dramatically with increasing altitude, so recommendations must differentiate whether the alpinist is at base camp, at high-altitude camps, or attempting the summit. This paper highlights nutritional recommendations regarding prioritising carbohydrates as a source of energy and trying to maintain a protein balance with a practical contextualisation in the extreme altitude environment in the different stages of an alpine expedition. More research is needed regarding specific macro and micronutrient requirements as well as the adequacy of nutritional supplementations at high altitudes.
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Liu, J. Y., C. Y. Lin und H. F. Tsai. „Electron density profiles probed by radio occultation of FORMOSAT-7/COSMIC-2 at 520 and 800 km altitude“. Atmospheric Measurement Techniques Discussions 8, Nr. 2 (04.02.2015): 1615–27. http://dx.doi.org/10.5194/amtd-8-1615-2015.
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Abstract. The FORMOSAT-7/COSMIC-2 (F7/C2) will ultimately place 12 satellites in orbit with two launches with 24° inclination and 520 km altitude in 2016 and with 72° inclination and 800 km altitude in 2019. In this study, we examine the electron density probed at the two satellite altitudes 500 and 800 km by means of FORMOSAT-3/COSMIC (F3/C) observations at the packing orbit 500 km altitude and mission orbit 800 km altitude, as well as observing system simulation experiments (OSSE). The electron density derived from 500 and 800 km satellite altitude of the F3/C observation and the OSSE confirm that the standard Abel inversion can correctly derive the electron density profile.
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Ashour, Amal Adnan. „High Altitude and Its Effects on Oral Health: A Review of Literature“. Journal of Advanced Oral Research 11, Nr. 2 (24.09.2020): 143–47. http://dx.doi.org/10.1177/2320206820942401.
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Health deterioration at high altitudes is related to many pathophysiological processes. The literature contains much evidence describing the multiple factors responsible for this deterioration, including hypoxia, decreased oxygen saturation, and decreased barometric pressure. An increase in the levels of oxidative stress at high altitudes can lead to many serious health events, although the human body may be able to adapt to such changes in the case of people who are accustomed to living at a high altitude. The pathophysiological processes at high altitudes also have adverse effects on oral tissue health. The aim of this review is to summarize the major published findings about oral health deterioration of living in and travelling to high-altitude areas. Most studies have noted the adverse effects of prolonged exposure to hypoxia at high altitudes on oral tissues, including the salivary gland, periodontal tissue, gingival crevicular fluids, and jawbone. These changes include increases in the levels of inflammatory mediators and periodontal inflammation parameters. In addition, the incidence and severity of dental fluorosis is higher in residents of high-altitude areas. Abrupt changes in barometric pressure in people who travel to high altitudes may cause dental barotrauma and appear to increase sensitivity to pain (barodontalgia). In conclusion, it is important to consider that travelling to and living in high-altitude areas is a possible risk factor for multiple oral diseases.
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Salvi, Paolo, Andrea Grillo, Sylvie Gautier, Luca Montaguti, Fausto Brunacci, Francesca Severi, Lucia Salvi, Enzo Pretolani, Gianfranco Parati und Athanase Benetos. „Haemodynamic Adaptive Mechanisms at High Altitude: Comparison between European Lowlanders and Nepalese Highlanders“. Journal of Clinical Medicine 11, Nr. 13 (02.07.2022): 3843. http://dx.doi.org/10.3390/jcm11133843.
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Background: Exposure to high altitudes determines several adaptive mechanisms affecting in a complex way the whole cardiovascular, respiratory, endocrine systems because of the hypobaric hypoxic condition. The aim of our study was to evaluate the circulatory adaptive mechanisms at high altitudes, during a scientific expedition in the Himalayas. Methods: Arterial distensibility was assessed measuring carotid-radial and carotid-femoral pulse wave velocity. Tests were carried out at several altitudes, from 1350 to 5050 m above sea level, on 8 lowlander European researchers and 11 highlander Nepalese porters. Results: In Europeans, systolic blood pressure and pulse pressure increased slightly but significantly with altitude (p < 0.05 and p < 0.001, respectively). Norepinephrine showed a significant increase after the lowlanders had spent some time at high altitude (p < 0.001). With increasing altitude, a progressive increase in carotid-radial and carotid-femoral pulse wave velocity values was observed in lowlanders, showing a particularly significant increase (p < 0.001) after staying at high altitude (carotid-radial pulse wave velocity, median value (interquartile range) from 9.2 (7.9–10.0) to 11.2 (10.9–11.8) m/s and carotid-femoral pulse wave velocity from 8.5 (7.9–9.0) to 11.3 (10.9–11.8) m/s). At high altitudes (3400 and 5050 m above sea level), no significant differences were observed between highlanders and lowlanders in hemodynamic parameters (blood pressure, carotid-radial and carotid-femoral pulse wave velocity). Conclusions: The progressive arterial stiffening with altitude observed in European lowlanders could explain the increase in systolic and pulse pressure values observed at high altitudes in this ethnic group. Further studies are needed to evaluate the role of aortic stiffening in the pathogenesis of acute mountain sickness.
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Debnath, Tushar, Dibakar Saha und Sumit Bhowmik. „Snow Layer Prediction Model using Back Scattering Co-efficient“. International Journal for Research in Applied Science and Engineering Technology 11, Nr. 2 (28.02.2023): 60–64. http://dx.doi.org/10.22214/ijraset.2023.48935.
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Abstract: In this study, the objective is to estimate the physical parameters of each snow layer at a given certain altitude, which is according to the problem will always be between other altitudes, whose profile data is entirely provided. The provided data for the target profile will also consist of the number of layers, height of each layer, the back-scattering coefficient and the altitude. The goal is to estimate the interval [࢟ ,࢞ࢇ࢟ [for each parameter, which are sphericity, diameter and density of the snowflakes. We are using here a multilayer snow profile and then applying the back scattering coefficients to calculate the snow layer altitude and height. Further, by correct prediction we can preserve the snow layers by continuously monitoring the snow model at the correct altitude throughout the year. Our aim demonstrates the comparatively better way to predict the best snow profile at right altitudes.
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Mairbäurl, Heimo, Max Gassmann und Martina U. Muckenthaler. „Geographical ancestry affects normal hemoglobin values in high-altitude residents“. Journal of Applied Physiology 129, Nr. 6 (01.12.2020): 1451–59. http://dx.doi.org/10.1152/japplphysiol.00025.2020.
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Increasing the hemoglobin (Hb) concentration is a major mechanism adjusting arterial oxygen content to decreased oxygen partial pressure of inspired air at high altitude. Approximately 5% of the world’s population living at altitudes higher than 1,500 m shows this adaptive mechanism. Notably, there is a wide variation in the extent of increase in Hb concentration among different populations. This short review summarizes available information on Hb concentrations of high-altitude residents living at comparable altitudes (3,500–4,500 m) in different regions of the world. An increased Hb concentration is found in all high-altitude populations. The highest mean Hb concentration was found in adult male Andean residents and in Han Chinese living at high altitude, whereas it was lowest in Ethiopians, Tibetans, and Sherpas. A lower plasma volume in Andean high-altitude natives may offer a partial explanation. Indeed, male Andean high-altitude natives have a lower plasma volume than Tibetans and Ethiopians. Moreover, Hb values were lower in adult, nonpregnant females than in males; differences between populations of different ancestry were less pronounced. Various genetic polymorphisms were detected in high-altitude residents thought to favor life in a hypoxic environment, some of which correlate with the relatively low Hb concentration in the Tibetans and Ethiopians, whereas differences in angiotensin-converting enzyme allele distribution may be related to elevated Hb in the Andeans. Taken together, these results indicate different sensitivity of oxygen dependent control of erythropoiesis or plasma volume among populations of different geographical ancestry, offering explanations for differences in the Hb concentration at high altitude.
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Persson, P. B., und A. Bondke Persson. „Altitude sickness and altitude adaptation“. Acta Physiologica 220, Nr. 3 (13.06.2017): 303–6. http://dx.doi.org/10.1111/apha.12894.