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Tang, Yan Fei, Chao Ding, Ya Ping He, De Chuang Zhou y Jian Wang. "Studies on the Effect of Altitude on the Flammable Liquids' Flash Point". Advanced Materials Research 908 (marzo de 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 y Rustum Karanjia. "Aircraft Cabin Pressurization and Concern for Non-Arteritic Anterior Ischemic Optic Neuropathy". Aerospace Medicine and Human Performance 91, n.º 9 (1 de septiembre de 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 y N.K. SHARMA. "Spatio-temporal variability of climatic parameters across different altitudes of North- Western Himalaya". Journal of Agrometeorology 21, n.º 3 (10 de noviembre de 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 y Benjamin D. Levine. "Defining the “dose” of altitude training: how high to live for optimal sea level performance enhancement". Journal of Applied Physiology 116, n.º 6 (15 de marzo de 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 de noviembre de 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. y P. Schatz. "Altitude and Concussions in the NFL: Is There Really a “Mile-High” Effect?" Archives of Clinical Neuropsychology 34, n.º 5 (julio de 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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Lu, Mengnan, Xiaona Wang, Shengnan Zhang, Shiyan Wang y Ji De. "Seed, Germination, and Seed-Reserve Traits of Ephedra saxatilis Differ Along Different Altitudinal Gradients in Tibet, China". Journal of Biobased Materials and Bioenergy 17, n.º 5 (1 de octubre de 2023): 582–90. http://dx.doi.org/10.1166/jbmb.2023.2310.
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Ephedra saxatilis, an important medicinal plant species belonging to the genus Ephedra, grows at a wide range of altitudes in Tibet, China. Collect seeds with different altitude gradients at low altitude (3500–4000 m), medium altitude (4000–4500 m), and high altitude (4500–5000 m), and study the effects of different altitude gradients on seed morphological traits, germination parameters, Seedling morphology, the morphological changes in the process of seed germination and uncracked seeds, 11 biochemical variables related to seed storage. Use correlation analysis to test the relationship between these variables. The process of seed germination is divided into five stages. Seeds that did not change color in stage III did not continue to grow. Seeds from low altitudes had significantly higher percentage of germination, and water contents and reducing sugars contents, but longer germination time. Seeds from high altitudes, however, had higher Xanthophyll, soluble phenolic, and ash contents. Among the examined biochemical variables, the germination rate at different altitudes was positively correlated with vitamin E, water content, and total flavonoid and soluble protein contents. Seedling growth state is divided into five stages. Our results confirm that seed differed significantly across different altitudinal gradients. Seeds of E. saxatilis from low altitudes had a survival advantage over those from medium and high altitudes.
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Shangpliang, P. Wankitlang, Rupa Nylla K. Hooroo, Graham Bakynson Ranee, Sudhanya Ray Hajong, Annu Kumari y Eugene Lyngkhoi. "Exploring Altitude's Influence: Contrasting Embryonic Development of Hyla annectans Jerdon in High and Low Altitude Environments". UTTAR PRADESH JOURNAL OF ZOOLOGY 45, n.º 7 (21 de marzo de 2024): 1–9. http://dx.doi.org/10.56557/upjoz/2024/v45i73967.
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The study investigated the embryonic development of Hyla annectans Jerdon, a frog species, at high and low altitude breeding sites of Meghalaya, North East India. Results revealed significant differences in the duration of embryonic development and hatching between the two altitudes. Embryos at low altitude sites exhibited a faster development, hatching approximately four days earlier than those at high altitude sites. Early embryonic stages displayed similar characteristics in size between the two sites, but distinct differences emerged during later stages, notably in stages associated with heart development, muscular response, and gill circulation. Furthermore, metamorphosis completion varied between altitudes, with a shorter duration observed at low altitude compared to high altitude. Environmental conditions, particularly water properties, also differed significantly between the two sites. Water temperature and free carbon dioxide levels were higher at low altitude, while pH and dissolved oxygen levels were higher at high altitude. These findings suggest a potential influence of altitudinal gradients as environmental factors on embryonic development in H. annectans.
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Gündeşli, Muhammet Ali, Remzi Uğur y Mehmet Yaman. "The Effects of Altitude on Fruit Characteristics, Nutrient Chemicals, and Biochemical Properties of Walnut Fruits (Juglans regia L.)". Horticulturae 9, n.º 10 (29 de septiembre de 2023): 1086. http://dx.doi.org/10.3390/horticulturae9101086.
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This study aimed to investigate changes in fruit characteristics, total phenolics, total antioxidant capacity, organic acids, sugar content, and fatty acid composition in ten walnut genotypes and three cultivars grown at different altitudes under Mediterranean climate conditions. At altitudes of 500 m and 1200 m, total phenolics ranged between 237.51 and 412.96 mg GAE/100 g dw and 234.94 and 392.31 mg GAE/100 g dw, respectively. According to DPPH radical inhibition, the total antioxidant capacity varied between 47.65% and 64.99% at an altitude of 500 m and between 57.76% and 68.92% at an altitude of 1200 m. The oil content demonstrated variations between 53.44% and 76.17% at an elevation of 500 m and between 43.11% and 67.03% at an altitude of 1200 m. At both 500 m and 1200 m altitudes, linoleic acid emerged as the predominant fatty acid and ranged from 58.82% to 62.44% at 500 m altitude and from 57.33% to 59.38% at 1200 m altitude. Notably, malic acid was identified as the primary organic acid, with concentrations ranging from 1.35% to 7.33% at both altitudes. In conclusion, this study demonstrates that walnut seeds are abundant in oil, protein, total phenolics, antioxidants, and fatty acids, with variations influenced by the cultivar or genotype and notably affected by altitude.
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Lei, Tian, Jinliang Xu, Xingli Jia, Leyu Wei y 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 de agosto de 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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Lennertz, Tracy, Andrea L. Sparko, Kim Cardosi, Alan Yost, Andrew Kendra, Jason Lu y Tom Sheridan. "Pilots’ Estimation of Altitude of a Small Unmanned Aircraft System (sUAS)". Proceedings of the Human Factors and Ergonomics Society Annual Meeting 62, n.º 1 (septiembre de 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 y 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, n.º 2 (16 de enero de 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, n.º 6 (1 de junio de 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, n.º 1 (1 de enero de 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 y 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, n.º 4 (11 de enero de 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 y 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, n.º 1 (enero de 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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Chapman, Robert F., Trine Karlsen, R. L. Ge, James Stray-Gundersen y Benjamin D. Levine. "Living altitude influences endurance exercise performance change over time at altitude". Journal of Applied Physiology 120, n.º 10 (15 de mayo de 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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Eskandar, Mamdoh, Wardah Alasmari, Fawaz Idris, Huda Nadwi, Enshrah Radwan, Tahir Mubarak y 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, n.º 1 (5 de enero de 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 y M. A. Escobedo. "Blood respiratory properties in pigeons at high altitudes: effects of acclimation". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 249, n.º 6 (1 de diciembre de 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 y 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, n.º 3 (25 de abril de 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 y TERSI ALESTI. "Karakteristik Fisiologis Lumut pada Beberapa Ketinggian di Kawasan Gunung Tangkuban Perahu". Jurnal Sumberdaya Hayati 1, n.º 2 (4 de mayo de 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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Susanto, Maghfirah y Muhammad Hasan. "Clinical Aspects of Highland Sickness and Climbing". Sriwijaya Journal of Forensic and Medicolegal 1, n.º 2 (16 de noviembre de 2023): 43–45. http://dx.doi.org/10.59345/sjfm.v1i2.64.
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Altitude sickness occurs when hypoxic stress is greater than the individual's ability to adapt. Risk factors for high altitude sickness include increased physical activity with inadequate acclimatization, inadequate education and preparation, individual susceptibility, and previous high altitude sickness. This review aims to describe the clinical aspects of high-altitude disease. There is a spectrum of neurological conditions caused by altitude, ranging from acute mountain sickness (AMS) to more serious forms, such as high-altitude cerebral edema (HACE). HACE includes symptoms of severe AMS and results from cerebral vasogenic edema and cerebral cellular hypoxia. This situation usually occurs at altitudes above 2500 meters (8202 feet) but can occur at lower altitudes. The main signs that occur are changes in mental status, ataxia, severe fatigue, and encephalopathy. HAPE is the leading cause of death from plateau disease. The characteristic feature is an increase in pulmonary artery pressure followed by pulmonary edema. Initial symptoms may appear within 6–36 hours after arriving in highland areas. In conclusion, the clinical severity of disease or death due to plateau disease is influenced by the speed and altitude of climbing as well as individual susceptibility.
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Wang, Yi, Hongchu Wang, Yinru Chen, Naxin Xu, Winson Lee y 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, n.º 14 (7 de julio de 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 y Laily Din. "The Diversity of Lichens along Elevational Gradients in the Tropical Montane Forest of Selangor, Malaysia". Sains Malaysiana 50, n.º 5 (31 de mayo de 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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Ortiz-Prado, Esteban, Juan S. Izquierdo-Condoy, Raúl Fernández-Naranjo, Jorge Vásconez-González, Leonardo Cano, Ana Carolina González, Estefanía Morales-Lapo et al. "Epidemiological characterization of ischemic heart disease at different altitudes: A nationwide population-based analysis from 2011 to 2021 in Ecuador". PLOS ONE 18, n.º 12 (29 de diciembre de 2023): e0295586. http://dx.doi.org/10.1371/journal.pone.0295586.
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Background Cardiovascular diseases, including ischemic heart disease, are the leading cause of premature death and disability worldwide. While traditional risk factors such as smoking, obesity, and diabetes have been thoroughly investigated, non-traditional risk factors like high-altitude exposure remain underexplored. This study aims to examine the incidence and mortality rates of ischemic heart disease over the past decade in Ecuador, a country with a diverse altitude profile spanning from 0 to 4,300 meters. Methods We conducted a geographic distribution analysis of ischemic heart disease in Ecuador, utilizing hospital discharge and mortality data from the National Institute of Census and Statistics for the years 2011–2021. Altitude exposure was categorized according to two distinct classifications: the traditional division into low (< 2,500 m) and high (> 2,500 m) altitudes, as well as the classification proposed by the International Society of Mountain Medicine, which delineates low (< 1,500 m), moderate (1,500–2,500 m), high (2,500–3,500 m), and very high (3,500–5,800 m) altitudes. Findings From 2011–2021, we analyzed 49,765 IHD-related hospital admissions and 62,620 deaths. Men had an age-adjusted incidence rate of 55.08/100,000 and a mortality rate of 47.2/100,000, compared to 20.77/100,000 and 34.8/100,000 in women. Incidence and mortality surged in 2020 by 83% in men and 75% in women. Altitudinal stratification revealed higher IHD rates at lower altitudes (<2500 m), averaging 61.65 and 121.8 per 100,000 for incidence and mortality, which declined to 25.9 and 38.5 at elevations >2500 m. Men had more pronounced rates across altitudes, exhibiting 138.7% and 150.0% higher incidence at low and high altitudes respectively, and mortality rates increased by 48.3% at low altitudes and 23.2% at high altitudes relative to women. Conclusion Ecuador bears a significant burden of ischemic heart disease (IHD), with men being more affected than women in terms of incidence. However, women have a higher percentage of mortality post-hospital admission. Regarding elevation, our analysis, using two different altitude cutoff points, reveals higher mortality rates in low-altitude regions compared to high-altitude areas, suggesting a potential protective effect of high elevation on IHD risk. Nevertheless, a definitive dose-response relationship between high altitude and reduced IHD risk could not be conclusively established.
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Lima, Paula Aparecida Muniz de, José Henrique Soler Guilhen, Khétrin Silva Maciel, Rodrigo Sobreira Alexandre, Adésio Ferreira y José Carlos Lopes. "Physiological quality of ‘BRS’ passion fruit seeds grown at different altitudes and storage environments". Comunicata Scientiae 14 (30 de septiembre de 2023): e3993. http://dx.doi.org/10.14295/cs.v14.3993.
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The aim of this work was to study the physiological quality of ‘BRS’ passion fruit seeds grown at different altitudes stored in cold chamber and in natural environment for six months. Hybrid passion fruit seeds (BRS Gigante Amarelo, BRS Sol do Cerrado and BRS Rubi do Cerrado) grown at three altitudes (104; 711; 1016 meters) in the southern region of the state of Espírito Santo were used. Germination was carried out in germitest paper rolls, placed in BOD-type germination chambers at temperature of 20-30 ºC. The following parameters were analyzed: germination, germination speed index, shoot and root length and dry mass of seedlings. The experimental design used was completely randomized in a factorial scheme with split plot in time 4x(3x3) (four bimonthly analyses x three hybrids x three altitudes), with two independent storage environments and three replicates of 100 seeds. Hybrid Passiflora edulis f. flavicarpa seeds can be stored in natural environment or cold chamber. Hybrid yellow passion fruit seeds grown at altitudes of 104 and 711 meters show higher germination and vigor percentages. Hybrid ‘Gigante Amarelo’ seeds had lower averages for variables under study, regardless of altitude. Hybrid ‘Rubi do Cerrado’ seeds grown at altitude of 1016 meters and hybrid ‘Sol do Cerrado’ seeds grown at altitudes of 104 and 711 meters have higher germination and vigor percentages and can be stored for 180 days in natural environment or cold chamber without viability loss. Flavicarpa can be stored in natural environment or cold chamber. Hybrid yellow passion fruit seeds grown at altitudes of 104 and 711 meters show higher germination and vigor percentages. Hybrid ‘Gigante Amarelo’ seeds had lower averages for variables under study, regardless of altitude. Hybrid ‘Rubi do Cerrado’ seeds grown at altitude of 1016 meters and hybrid ‘Sol do Cerrado’ seeds grown at altitudes of 104 and 711 meters have higher germination and vigor percentages and can be stored for 180 days in natural environment or cold chamber without viability loss. Passiflora edulis f. flavicarpa can be stored in natural environment or cold chamber. Hybrid yellow passion fruit seeds grown at altitudes of 104 and 711 meters show higher germination and vigor percentages. Hybrid ‘Gigante Amarelo’ seeds had lower averages for variables under study, regardless of altitude. Hybrid ‘Rubi do Cerrado’ seeds grown at altitude of 1016 meters and hybrid ‘Sol do Cerrado’ seeds grown at altitudes of 104 and 711 meters have higher germination and vigor percentages and can be stored for 180 days in natural environment or cold chamber without viability loss. Hybrid ‘Gigante Amarelo’ seeds had lower averages for variables under study, regardless of altitude. Hybrid ‘Rubi do Cerrado’ seeds grown at altitude of 1016 meters and hybrid ‘Sol do Cerrado’ seeds grown at altitudes of 104 and 711 meters have higher germination and vigor percentages and can be stored for 180 days in natural environment or cold chamber without viability loss. Hybrid ‘Gigante Amarelo’ seeds had lower averages for variables under study, regardless of altitude. Hybrid ‘Rubi do Cerrado’ seeds grown at altitude of 1016 meters and hybrid ‘Sol do Cerrado’ seeds grown at altitudes of 104 and 711 meters have higher germination and vigor percentages and can be stored for 180 days in natural environment or cold chamber without viability loss.
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Yao, Xiuyuan, Yu Su, Songsong Zhou, Yujian Ding, Yifan Lin, Ling Jiang y Shijun Xie. "Gap distance of UHV substation in areas with an altitude of 5000 m and below". Journal of Physics: Conference Series 2797, n.º 1 (1 de julio de 2024): 012015. http://dx.doi.org/10.1088/1742-6596/2797/1/012015.
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Abstract In view of the increasing energy consumption and power demand, the construction of UHV AC is growing rapidly, and the construction of the project is gradually advancing to higher altitudes. It is urgent to conduct research on typical gap discharge in substations at high altitudes. Combined with the engineering requirements, this paper corrects the test data at an altitude of 0 m according to GB/T 24842 standard through altitude correction and combines the discharge voltage requirements of various typical gaps in substations to obtain the minimum air gap distance in UHV substations at an altitude of 5000 m and below. The calculation results of the two altitude correction methods are compared and analyzed, and the applicability of the two methods is analyzed.
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Liang, Tao, Weilin Tao, Yan Wang, Na Zhou, Wei Hu, Tao Zhang, Dunxiu Liao, Xinping Chen y Xiaozhong Wang. "The Extension of Vegetable Production to High Altitudes Increases the Environmental Cost and Decreases Economic Benefits in Subtropical Regions". Land 12, n.º 3 (11 de marzo de 2023): 662. http://dx.doi.org/10.3390/land12030662.
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Global warming has driven the expansion of cultivated land to high-altitude areas. Intensive vegetable production, which is generally considered to be a high economic value and high environmental risk system, has expanded greatly in high-altitude mountainous areas of China. However, the environmental cost of vegetable production in these areas is poorly understood. In this study, pepper production at low (traditional pepper production area) and high (newly expanded area) altitudes were investigated in Shizhu, a typical pepper crop area. The output and environmental cost at the two altitudes were identified. the influence of resource inputs, climate, and soil properties on pepper production was evaluated. There were obvious differences in output and environmental cost between the two altitudes. High-altitude pepper production achieved a 16.2% lower yield, and had a higher fertilizer input, resulting in a 22.3% lower net ecosystem economic benefit (NEEB), 23.0% higher nitrogen (N) footprint and 24.0% higher carbon (C) footprint compared to low-altitude farming. There is potential for environmental mitigation with both high- and low-altitude pepper production; Compared to average farmers, high-yield farmers groups reduced their N and C footprints by 16.9–24.8% and 18.3–25.2%, respectively, with 30.6–34.1% higher yield. A large increase in yield could also be achieved by increasing the top-dress fertilizer rate and decreasing the plant density. Importantly, high-altitude pepper production was achieved despite less advanced technology and inferior conditions (e.g., a poor road system and uneven fields). It provides a reference for the study of the environmental cost of other high-altitude regions or other crop systems at high-altitude areas.
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Stothard, Ellen, Mark Hickey y Christine Ebert-Santos. "0164 Overnight Oximetry in Generationally Un-Adapted Residents of High-Altitude". Sleep 45, Supplement_1 (25 de mayo de 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 y Sushan Man Shrestha. "Oxygen saturation at different altitudes in Nepal among adults". Grande Medical Journal 2, n.º 1 (28 de diciembre de 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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Ginoga, Lin Nuriah, Siti Badriyah Rushayati y Inu Fauzan Hawari. "The effect of altitude on the butterfly diversity in the Gunung Gede Pangrango National Park, West Java, Indonesia". Jurnal Pengelolaan Sumberdaya Alam dan Lingkungan (Journal of Natural Resources and Environmental Management) 14, n.º 2 (30 de mayo de 2024): 210. http://dx.doi.org/10.29244/jpsl.14.2.210.
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Altitude is one of the factors that decrease butterfly diversity due to the different types of habitats. Gunung Gede Pangrango National Park is one of the places at different altitudes, such as Situgunung Resort. This study aimed to investigate butterfly species' diversity, richness, and evenness at three altitude levels. This study was completed in October 2019 at altitudes 750, 850, and 950 meters above sea level (masl). Butterfly inventory (diversity) data were collected using the transect method, and data on habitat characteristics were acquired through direct observation. The richness, diversity, evenness, and community similarity of butterfly species and the biotic and abiotic habitat characteristics were then analyzed. The result showed 51 butterfly species at Situgunung Resort, Gunung Gede Pangrango National Park. The highest diversity index and richness index were found at an altitude of 750 masl (3.22 and 7.91) and the lowest at 950 masl (2.46 and 3.98). The highest evenness index was found at 750 masl, while the highest similarity community index was found at altitudes 750 and 850 masl. The relation between altitude and butterfly diversity is that the higherthe altitude, the lower the butterfly diversity.
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Chi Lin, Bo Zhang, Xiaolong Zhao, Donglin Xu, Taoxi Zong, Yong Shen, Yanxiang Tong, Shiying Chen, Weihua Chu y Linjie Wei. "Hyperuricemia as a risk factor for cerebral hemorrhage in young and middle-aged hypertensive patients at high altitude". Neurology Asia 29, n.º 2 (junio de 2024): 293–300. http://dx.doi.org/10.54029/2024jyx.
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Background: The purpose of this research was to investigate the effect of uric acid on hypertensive intracerebral hemorrhage (HICH) in young and middle-aged hypertensive patients at high altitude. Methods: High-altitude and low-altitude HICH patients were analyzed retrospectively, and the influence of uric acid on hemorrhage was analyzed by the correlations between age and uric acid, between age and hemoglobin, and between uric acid and hemoglobin. The individuals in the high- and low-altitude groups were assigned to a young/middle-aged group and an elderly group, and the correlation between age and uric acid was analyzed. The risk factors for HICH were analyzed by logistic regression analysis. ROC curve analysis was used to investigate the relationship between risk factors and cerebral hemorrhage. Results: Age was negatively correlated with uric acid concentration in patients with HICH at high altitudes but not in patients with HICH at low altitudes. In addition, age was negatively correlated with hemoglobin in patients with HICH at high altitudes but not in patients with HICH at low altitudes. Uric acid was negatively correlated with age in young and middle-aged adults at high altitudes but not in elderly individuals. Diastolic pressure, uric acid and sex were risk factors for HICH in young and middle-aged adults at high altitudes. ROC curve showed that uric acid and diastolic pressure had diagnostic significance. Conclusions: High levels of uric acid is correlated with increased risk of cerebral hemorrhage in young and middle-aged adults with hypertension in high altitude.
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Subedi, Dharma Datta, Muza Shrestha, Biyush Pokharel, Prabodh Regmi y 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, n.º 2 (30 de agosto de 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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Salvi, Paolo, Andrea Grillo, Fausto Brunacci, Francesca Severi, Luca Montaguti, Sylvie Gautier, Lucia Salvi, Enzo Pretolani, Gianfranco Parati y Athanase Benetos. "Microcirculatory and Rheological Adaptive Mechanisms at High Altitude in European Lowlander Hikers and Nepalese Highlanders". Journal of Clinical Medicine 12, n.º 8 (14 de abril de 2023): 2872. http://dx.doi.org/10.3390/jcm12082872.
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Background: Physical activity at high-altitudes is increasingly widespread, both for tourist trekking and for the growing tendency to carry out sports and training activities at high-altitudes. Acute exposure to this hypobaric–hypoxic condition induces several complex adaptive mechanisms involving the cardiovascular, respiratory and endocrine systems. A lack of these adaptive mechanisms in microcirculation may cause the onset of symptoms of acute mountain sickness, a frequent disturbance after acute exposure at high altitudes. The aim of our study was to evaluate the microcirculatory adaptive mechanisms at different altitudes, from 1350 to 5050 m a.s.l., during a scientific expedition in the Himalayas. Methods: The main haematological parameters, blood viscosity and erythrocyte deformability were assessed at different altitudes on eight European lowlanders and on a group of eleven Nepalese highlanders. The microcirculation network was evaluated in vivo by conjunctival and periungual biomicroscopy. Results: Europeans showed a progressive and significant reduction of blood filterability and an increase of whole blood viscosity which correlate with the increase of altitude (p < 0.02). In the Nepalese highlanders, haemorheological changes were already present at their residence altitude, 3400 m a.s.l. (p < 0.001 vs. Europeans). With the increase in altitude, a massive interstitial oedema appeared in all participants, associated with erythrocyte aggregation phenomena and slowing of the flow rate in the microcirculation. Conclusions: High altitude causes important and significant microcirculatory adaptations. These changes in microcirculation induced by hypobaric–hypoxic conditions should be considered when planning training and physical activity at altitude.
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Suchý, Jiří, Jiří Novotný y Pavel Tilinger. "Porovnání vlivu hyperoxie na krátkodobý anaerobní výkon v nížině a vyšší nadmořské výšce". Studia sportiva 4, n.º 1 (7 de julio de 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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Ghelichnia, H. "Essential Oil Composition of Thymus fedtschenkoi Ronniger at Different Growing Altitudes in Mazandaran, Iran". Cercetari Agronomice in Moldova 51, n.º 2 (1 de junio de 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, n.º 1 (5 de marzo de 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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ACARSOY BİLGİN, Nihal y Adalet MISIRLI. "The effect of different altitudeson nut properties and yield in “Chandler” walnut variety". Ege Üniversitesi Ziraat Fakültesi Dergisi 60, n.º 4 (5 de diciembre de 2023): 639–46. http://dx.doi.org/10.20289/zfdergi.1266186.
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Objective: It was aimed to evaluate and interpret nut parameters of “Chandler”walnut variety at two different altitudes according to years.
Material and Methods: Thisresearch was conducted in a commercial orchard located at an altitude of 50 and 750 m in Manisa province during 2017 and 2021 years. “Chandler” walnut variety was used as plant material.
Results: Accordingly, the highest nut weight was determined as 13.89 g at 50 m altitude in 2018. The highest nut width, length, and height values were detected in the same year and altitude. For altitudes of 50 m and 750 m, the shell thickness was thin (1.38 mm and 1.30 mm) in 2020,whereas it was thick (2.16 mm and 1.83 mm) in 2019. A light kernel color was stated at 750 m in 2019. The shrinkage value was found to be much less at 750 m (9.41%). Higher yield was obtained at 50 m altitude. On the other hand, In the principal component analysis, the most important distinguishing features in terms of years were kernel weight for 50 m and kernel ratio for 750 m altitudes.
Conclusion: It was detected that the nut characteristicssuch as kernel ratio, nut length, L* value and shrinkage ratiowere superiordue to the increase in altitude. However, the yield was found to be higher at low altitudes.
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Wagenhäuser, Thomas, Andreas Engel y Robert Sitals. "Testing the altitude attribution and vertical resolution of AirCore measurements with a new spiking method". Atmospheric Measurement Techniques 14, n.º 5 (27 de mayo de 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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Jiao, Jun, Bifeng Song, Yubin Li, Yugang Zhang y Jianhua Xu. "Development of a testing methodology for high-altitude propeller". Aircraft Engineering and Aerospace Technology 90, n.º 9 (14 de noviembre de 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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Nepal, O., BR Pokharel, K. Khanal, P. Gyawali, SL Malik, R. Koju y BK Kapoor. "Thyroid Hormone levels in Highlanders- A Comparison Between Residents of Two Altitudes in Nepal". Kathmandu University Medical Journal 11, n.º 1 (9 de septiembre de 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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Lestari, M.Env., Ratri Yuli, Dwi Harsono y 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, n.º 1 (27 de diciembre de 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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Han, Kaiyue, Xiaoling Su, Jiang Liu, Fengcai Yao y 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 (7 de marzo de 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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Vidojević, Dragana, Maja Manojlović, Aleksandar Đorđević, Radovan Savić, Ljiljana Nešić y Božidar Đokić. "Soil organic carbon stocks in relation to the altitude in Serbia". Zemljiste i biljka 70, n.º 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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CANVERDİ, Nazlı, Gonca ÖZMEN ÖZBAKIR, Soner ÇANKAYA, Muzaffer DUMAN, Ümit KAYABOYNU, Fatih YILMAZ, Hasan ESE y Belgin GÜNBEY. "The effects of altitude and rearing period on some characteristics of honey bee queens, Apis mellifera caucasica Gorbachev, 1916 (Hymenoptera: Apidae)". Turkish Journal of Entomology 47, n.º 3 (30 de septiembre de 2023): 295–306. http://dx.doi.org/10.16970/entoted.1207868.
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In the study, some characteristics of honey bee queens, Apis mellifera caucasica Gorbachev, 1916 (Hymenoptera: Apidae), reared at two different altitudes (140 m vs 920 m) and three rearing seasons (May, June-I, June-II) in 2019-2020 were examined in Ordu. These are larvae grafting, length of the queen cell, weight of queens at various periods, and spermathecae parameters of queens. One-day old 50 larvae were grafted at each period and altitude. The effect of period and period*altitude interaction on the weight at emergence of queen was significant (p<0.001) while the effect of altitude and year was nonsignificant. Weights at emergence of queens were lower in May at high altitudes and in June-II at low altitudes. The effects of year, period and altitude were significant (p<0.001) in the terms of the diameter and volume of the spermathecae, and the number of spermatozoa in the spermathecae. When the two-year data was evaluated together, the number of spermatozoa in the spermathecae was higher in the queen bees reared in May. It is recommended to pay attention to the period and altitude when pollen and nectar flow is intense in queen rearing in Ordu and similar climatic conditions.
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Spring, Allison M., Kenneth D. Domingue, Thomas V. Kerber, Margaret M. Mooney, Rebecca L. Hale, Kristina M. Lemmer y Kathryn M. Docherty. "Land Use Effects on Airborne Bacterial Communities Are Evident in Both Near-Surface and Higher-Altitude Air". Diversity 13, n.º 2 (18 de febrero de 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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Li, Zhipeng, Qiang Zhang, Fujun Zhang y Hongbo Liang. "Experimental investigation of the effect of altitude on efficiency and emissions of a diesel engine". Thermal Science, n.º 00 (2023): 194. http://dx.doi.org/10.2298/tsci230227194l.
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The diesel engine is expected to be available for operation at high altitude. However, power loss and emission deterioration have been plaguing highland diesel engines. Therefore, this study aimed to investigate the impact of altitude on the performance and combustion characteristics of diesel engines that is limited discussed in existing studies. The research was conducted by varying the altitude from 0-4,500m using a research diesel engine and analyzing the combustion characteristics at different combustion phases with the help of triple Wiebe function. The results indicated a noticeable drop in power output with increasing altitude, and the deterioration of performance and emissions became significant when the altitude exceeded 3,000m. Specifically, the indicated specific CO, unburnt hydrocarbon, and soot emissions increased while nitrogen oxides showed a reverse trend. Additionally, it was found that the lower cylinder pressure at high altitude extended the ignition delay and caused a higher heat release rate in the premixed combustion stage. Moreover, the high altitude condition shortened the duration of combustion and reduced the energy release fraction in the diffusion phase. Furthermore, the late combustion phase occurred earlier and lasted longer at high altitude, which consequently reduced the combustion and thermal efficiency. The most important finding is that the engine performance, especially the combustion efficiency, shows an abrupt degradation with altitudes above 3000 meters. As a result, engines operating at extremely high altitudes require multi-stage turbocharging to compensate for combustion deterioration.
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HALL, J. W., D. G. STOUT y 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, n.º 2 (1 de abril de 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 y Iveta Kameníková. "Temperature Effect to Altitude Corrections and Operational Application". MAD - Magazine of Aviation Development 8, n.º 1 (29 de marzo de 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 y Guru Das Bagchi. "Oil Constituents of Artemisia nilagirica var. septentrionalis Growing at Different Altitudes". Natural Product Communications 5, n.º 12 (diciembre de 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.