Low-altitude Regions Research Articles

Influence of Spring Water Residence Time on the Irrigation Water Stability in the Hani Rice Terraces

The stability of irrigation water is critical for the sustainability of alpine agriculture. Based on monthly precipitation and terraced field water and spring water samples obtained between 2015 and 2016, the study used the mean residence time and isotope mixing model to analyze the influence of spring water residence time on irrigation water stability in the Hani Rice Terraces. The results indicate that: (1) The mean residence time of precipitation and terraced field water in spring water was 2.46 years and 1.55 years, respectively, implying that the terraced field’s irrigation water source could be refilled by spring water recharged 1.5–2.5 years ago. (2) The mean residence time of precipitation in ascending and descending springs was 2.73 years and 1.95 years, respectively. The mean residence time of terraced field water in ascending and descending springs was 1.54 years and 1.04 years, respectively. The ascending spring’s recharge water residence time is 0.5–0.8 years longer than that of the descending spring, indicating that the spring water exhibits intra-seasonal and inter-seasonal staggered peak recharging. At the same time, the total recharge period of the ascending–descending spring is extended to 1–3 years, which means the terraced fields have a drought resistance of three years. (3) The mean residence time of precipitation and terraced field water at higher altitudes in the ascending spring is 2.52 times and 3.73 times, respectively, while in the descending spring, it is 3.36 times and 6.49 times to the lower altitude region. This means that the mean residence time of the recharge water source in the lower terraced fields was shorter, and the elevation difference between ascending and descending springs was smaller, thereby regulating the spatial homogeneous distribution of recharge water sources in the terraced fields.

Identification of Selection Signatures and Candidate Genes Related to Environmental Adaptation and Economic Traits in Tibetan Pigs.

Tibetan pigs are indigenous to the Qinghai-Tibet Plateau and have been the subject of extensive genomic research primarily focused on their adaptation to high altitudes. However, genetic modifications associated with their response to low-altitude acclimation have not been thoroughly explored. To investigate the genetic basis underlying the low-altitude acclimation of Tibetan pigs, we generated and analyzed genotyping data of Tibetan pigs that inhabit high-altitude regions (average altitude 4000 m) and Tibetan pigs that have inhabited nearby low-altitude regions (average altitude 500 m) for approximately 20 generations. We found that the highland and lowland Tibetan pigs have distinguishable genotype and phenotype variations. We identified 46 and 126 potentially selected SNPs associated with 29 and 56 candidate genes in highland and lowland Tibetan pigs, respectively. Candidate genes in the highland Tibetan pigs were involved in immune response (NFYC and STAT1) and radiation (NABP1), whereas candidate genes in the lowland Tibetan pigs were related to reproduction (ESR2, DMRTA1, and ZNF366), growth and development (NTRK3, FGF18, and MAP1B), and blood pressure regulation (CARTPT). These findings will help to understand the mechanisms of environmental adaptation in Tibetan pigs and offer valuable information into the genetic improvement of Tibetan pigs pertaining to low-altitude acclimation and economic traits.

Diversity and productive potential of segregating soybean populations for low altitude and high temperature regions

The diversity of segregating soybean populations is fundamental for the selection of lines that are increasingly adapted and stable to the region and that take advantage of the cultivar x environment interaction. Thus, the objective was to evaluate the genetic diversity and adaptability of segregating soybean populations to low altitudes and high temperatures. Nine soybean populations were obtained with a relative maturity degree (GMR) between 5.0 and 6.5. In all populations, lines with greater productive potential than the control were obtained with a GMR of 5.8 to 6.2. The genetic variability of the populations was wide for the production components. Genetic diversity indicated the qualitative and cycle length variables as the most important for differentiating populations. Thus, it is concluded that: the segregating soybean populations present genetic variability and adequate averages for characteristics of economic importance and the Delta 59I60 IPRO RSF x BS 2606 IPRO cross is more promising.

Assessment of mycotoxin contamination in Rwanda: A comparison of agro-ecological zones

Aflatoxin contamination of maize in Rwanda and underlying causes are poorly documented. This study aimed to address this gap where maize samples for aflatoxins analysis were collected from two different agro-ecological zones and the temperature and relative humidity conditions during the time preceding sample collection were monitored to determine the conditions conducive to this contamination. Maize was analysed for moisture content and aflatoxin contamination and the temperature and humidity data were used to estimate the saturation deficit of the ambient air as an indicator of risk of contamination, which is high when the saturation deficit is low. Results showed an average lower saturation deficit of 0.0018 kg H₂O kg−1 in the high-altitude Volcanic region compared to the 0.00095 kg H₂O kg−1 recorded in the lower altitude region of the Eastern Savannah. Given the high moisture content in most of the analysed samples, this meant that it is more challenging to dry maize to the safe storage moisture content in the Volcanic region compared to the Eastern Savannah. The mean aflatoxin contamination was 40.45 μg kg−1 in the Volcanic region significantly higher than 4.66 μg kg−1 in the Eastern Savannah. Aflatoxin G1 was predominant among the contaminated samples. Affordable drying technologies that use renewable sources of energy should be developed and made accessible to farmer cooperatives.

Knowledge, attitude, and practices toward malaria among hospital outpatients in Nangarhar, Afghanistan: A cross-sectional study.

In the Eastern Mediterranean region, Afghanistan ranks third for the world's highest burden of malaria. The vast majority (95%) of malaria cases in Afghanistan are attributed to Plasmodium falciparum and 5% to Plasmodium vivax. Most cases occur in low-altitude regions, especially in the eastern province of Nangarhar, where agriculture and farming are predominant. To better understand the public sentiment toward malaria, this study aimed to understand the knowledge, attitude, and practice of patients toward malaria who visited public and private hospitals of Nangarhar province. A cross-sectional descriptive study was conducted on Nangarhar residents who visited the adult Outpatient departments of eight local public and private health facilities. Data collection took place from 1st August 2022 to 15th September 2022. Of 700 participants, 37.9% (n = 265) identified as male and 62.1% (n = 435) identified as female. The majority of participants (84.6 %) were within the (18-40) age range, followed by 12.7% in the (41-60) age range, and 2.7% were aged 61 years or older. Moreover, 99.7% (n = 698) of the participants had heard of malaria. The main sources of information about malaria were family members (31.3%, n = 219), television (32.6%, n = 228), Internet (12.6%, n = 88), school (11.3%, n = 79), and health facilities (31.4%, n = 220). Most respondents correctly identified mosquito bites as the primary mode of malaria transmission (72.6%, n = 508). Others suggested that transmission could occur by close contact with a malaria patient (14.0%, n = 98) and drinking contaminated water (17.3%, n = 121). The majority of participants (70.6%) agreed that malaria is a serious and life-threatening disease. A significant number of participants (96.6%) reported owning an insecticide-treated mosquito net at home, and 87.0% reported using the net. Overall, participants reported good knowledge, attitude, and practice toward malaria. This may be linked to the awareness campaigns and preventive programs in Nangarhar province that have contributed to participant's willingness to prevent malaria and treat themselves if they get infected. Public health campaigns are difficult in Afghanistan with weak governance and conflict, and thus, populations may find themselves at risk if health promotion activities are stopped.

Epidemiological characterization of ischemic heart disease at different altitudes: A nationwide population-based analysis from 2011 to 2021 in Ecuador.

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. 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. 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. 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.

Boll distribution in the cotton canopy is affected by nitrogen management and cover crops in a sandy soil under water scarcity

Context or problemA favorable cotton boll distribution within the plant canopy can promote early fruit retention and increase crop yield and fiber quality, particularly in rainfed crops in sandy soils that are subject to periodic water deficits. However, the effects of different cover crop rotation systems combined with different nitrogen (N) rates and sources on boll distribution and cotton earliness are unknown. Objective or research questionThe objective of this study was to evaluate the boll distribution and earliness of cotton as a function of the cover crop rotation system and N sources and rates, in a sandy soil of a tropical region of Brazil prone to drought. MethodsA field study was carried out for two growing seasons (2018–2020) in southeastern Brazil in an area with sandy soil. The treatments consisted of the following crop rotation systems, which were implemented in 2016: Fallow; single grass; grass + grass; grass + legume; and MIX (grass+legume+grass). In addition, N rates of 70, 100, and 130 kg ha−1 (applied as topdressing) and two N sources (urea; and controlled-release urea, CRU) were evaluated. ResultsLow water availability in the 2018/2019 crop season resulted in early plants that reached 95% boll yield below fruiting node 12 when 70 kg ha−1 N (urea) was applied. Satisfactory rainfall in the 2019/2020 crop season resulted in 95% boll yield below fruiting node 14 when 130 kg ha−1 N was applied for all N sources and rotation systems. Applying CRU increased the boll distribution in the top third of the plant. Applying 130 kg ha−1 N increased the boll distribution in the middle and top thirds of the plant, particularly in the treatments with legume cover crops and CRU. In the crop season with higher rainfall and yield potential, the rotation systems without legumes that received 70 kg ha−1 N (urea) had a lower boll distribution in the top third of the plant. ConclusionsCotton boll distribution is affected by cover crop rotation systems, N rates and sources and water availabity throughout the season. The best strategy for improving early boll setting is to apply lower rates of N as CRU in a rotation system with a mixture of grasses and legumes as cover crops. Additionally, there is still a challenge to increase the cotton earliness in years with high water availability. Implications or significanceCover crops and increased efficiency fertilizers are important to improve boll setting throughout the entire cotton canopy. Because these technologies improve the availability of nitrogen and water in the soil, especially in dry years. Improving cotton earliness is still a challenge in low-altitude regions, since plant cycle is naturally short in these environments, due to the greater accumulation of degrees days. Even so, the use of lower N rates associated with cover crops and controlled-release urea may have a small increase in cotton earliness, but mainly help in early fruit retention.

Comparative Analysis of Starlight Occultation Data Processing

In order to improve the inversion accuracy of stellar occultation data and to provide a reference for the selection of inversion methods with higher accuracy in the future, this study compared and analyzed the inversion effects of two different methods on the same set of data, which are the effective cross-section method and the onion-peeling method, respectively. Firstly, the inversion principle of the effective cross-section method is introduced in detail. The regularisation parameters and screening conditions for the observation data in the inversion process were clarified based on the ozone observation characteristics. Second, the algorithm was applied to invert the GOMOS observational data from 1 December 2002. The atmospheric radiative transmittance obtained from the observations was filtered, and the inversion results were compared with those obtained using the onion-peeling method. Third, the errors in the height distribution obtained by both methods were calculated using the GOMOS secondary results from 1 December 2002 as the reference value. Finally, the inversion errors of other trace components were computed to further validate the accuracy of the two methods. The results demonstrate that the effective cross-sectional method is more accurate for the inversion of ozone, particularly in low-altitude regions affected by refraction. The method achieved a maximum error of 1.2%, with an apparent magnitude of 2, an effective temperature greater than 10,000 K, and a regularisation parameter of 1015. Furthermore, when applying the same method to the inversion of nitrogen trioxide and calculating the error, it was observed that the results of both methods were comparable at altitude of 30–60 km, with an error value ranging from 0 to 2%. However, at approximately 25 km, the inversion accuracy of the onion-peeling method surpassed that of the effective cross-sectional method. This research provides a theoretical foundation for further investigation of the stellar occultation inversion method and enhancing the accuracy of inversions.

Gut Microbial Diversity Analysis of Different Native Chickens and Screening of Chicken-Derived Probiotics

The gut microbiota plays a critical role in the growth, development, nutritional digestion, and overall health of chickens. Furthermore, certain probiotics isolated from poultry intestines have demonstrated the potential to enhance immune function and production performance in chickens. To investigate the differences in gut microbiota among chickens from various geographical environments and different breeds of broiler and laying hens, we conducted 16S rRNA sequencing on the fecal microbiota of 140 Chinese native chickens and ten Roman layers. In addition, we isolated and screened the potential probiotics to examine their biological characteristics, genome profiles, and functionality in animals. Our findings revealed the significant variations in gut microbiota composition and structure between Tibetan chickens (ZJ), which reside in high-altitude regions, and Meihua chickens (MH) and Xuhai chickens (XH), which inhabit low-altitude regions. Specifically, Cupriavidus and Candidatus_Bacilloplasma were identified as unique microbial communities in high and low altitudes, respectively. Notably, among regions with similar altitudes, Luning chickens (LN) exhibited the lowest α diversity, accompanied by a remarkably high relative abundance of Firmicutes and Lactobacillus. Conversely, Wugu chickens (WGs) and Yaoshan chickens (YSs) displayed similar gut microbiota profiles. Furthermore, distinctive gut microbiota patterns were observed between the different breeds of broilers and laying hens. Commercial Roman layers (LMs) exhibited significantly lower alpha diversity compared to native chickens, and broilers and laying hens predominantly harbored Firmicutes, Bacteroidota, and Proteobacteria. Of particular interest, the probiotics Lactobacillus agilis MH1 and Lactobacillus salivarius ZJ1, derived from chicken feces, exhibited favorable genomic profiles, and demonstrated anti-colitis effects and immunomodulatory functions. These findings provide a crucial theoretical foundation for native chicken research and offer insights for the future development and formulation of chicken-derived probiotics.

Abstract 12815: The Effect of Altitude on Cardiovascular Disease Mortality: Insights From a National Database in Ecuador

Introduction: Cardiovascular disease (CVD) is a leading cause of mortality worldwide. European population studies have shown a protective effect of high altitude on CVD mortality, but the applicability of these findings to Latin population remains to be explored. We aim to compare the mortality rates from ischemic heart disease (IHD), heart failure (HF), and cardiac arrhythmias between low- and high-altitude regions in Ecuador. Hypothesis: CVD mortality might be influenced by altitude Methods: We collected nationwide mortality data on different CVDs for each canton in Ecuador from 2017 to 2021 by using pre-defined ICD-10 codes. Then, we collected the mean altitude in meters above sea level (ASL) for each specific canton and classified them into low-(&lt;2500 meters ASL) and high-altitude (&gt;2500 meters ASL) cantons. We estimated the aggregated mortality rates per 100.000 persons and 95% confidence interval for high- and low-altitude regions at each timepoint. Results: From 2017 to 2021, 69.002 deaths due to CVDs occurred in Ecuador (IHD: 77.0%, HF:19.8% and cardiac arrhythmias: 3.2%). Mean age at death across different pathologies ranged between 76 and 81 years old, and most participants identified as multi-ethic (Table 1). There was a significantly higher mortality rate for HF and cardiac arrhythmias in high-altitude cantons than in low-altitude cantons at almost all timepoints (Figure 1). The mortality rates for IHD were lower for high-altitude cantons than low-altitude cantons at all timepoints. Conclusions: High-altitude cantons in Ecuador had higher mortality rates for HF and cardiac arrhythmias, but lower mortality rates for IHD when compared to low-altitude cantons.

Genomic formation of Tibeto-Burman speaking populations in Guizhou, Southwest China

Sino-Tibetan is the most prominent language family in East Asia. Previous genetic studies mainly focused on the Tibetan and Han Chinese populations. However, due to the sparse sampling, the genetic structure and admixture history of Tibeto-Burman-speaking populations in the low-altitude region of Southwest China still need to be clarified. We collected DNA from 157 individuals from four Tibeto-Burman-speaking groups from the Guizhou province in Southwest China. We genotyped the samples at about 700,000 genome-wide single nucleotide polymorphisms. Our results indicate that the genetic variation of the four Tibeto-Burman-speaking groups in Guizhou is at the intermediate position in the modern Tibetan-Tai-Kadai/Austronesian genetic cline. This suggests that the formation of Tibetan-Burman groups involved a large-scale gene flow from lowland southern Chinese. The southern ancestry could be further modelled as deriving from Vietnam’s Late Neolithic-related inland Southeast Asia agricultural populations and Taiwan’s Iron Age-related coastal rice-farming populations. Compared to the Tibeto-Burman speakers in the Tibetan-Yi Corridor reported previously, the Tibeto-Burman groups in the Guizhou region received additional gene flow from the southeast coastal area of China. We show a difference between the genetic profiles of the Tibeto-Burman speakers of the Tibetan-Yi Corridor and the Guizhou province. Vast mountain ranges and rivers in Southwest China may have decelerated the westward expansion of the southeast coastal East Asians. Our results demonstrate the complex genetic profile in the Guizhou region in Southwest China and support the multiple waves of human migration in the southern area of East Asia.

Growth, yield and metabolite substantiated, eco-physiological evaluation of overcoming accessional and agro-climatic differences in ex-situ raised Valeriana jatamansi Jones. at lower altitude of Sikkim Himalayan region

Valeriana jatamansi Jones. syn. V. wallichi (Family: Caprifoliaceae) is globally known and amongst the 27 listed medicinal plants under National AYUSH Mission (NAM) by National Medicinal Plants Board, New Delhi, Government of India. V. jatamansi is a temperate Himalayan critically vulnerable plant enlisted as plants of conservation concern under Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) Appendix-II with regulated foreign trade. Deplete wild population of V. jatamansi has prioritized conservation via ex-situ raising. The study conducted for V. jatamansi ex-situ raising at Sikkim Himalayan low altitude (tropical hills) region in different potting mix and evaluated for growth, yield and metabolite content substantiated with eco-physiological parameters. The eco-physiological parameters include pigment variations, stability, and the amount of hydroxyvalerenic acid & valerenic acid in below ground quantified using reversed phase-high performance liquid chromatography (RP-HPLC). The study reveals black soil (BS), forest soil (FS), Vermi-compost (VC) and Sand (S) favoured the growth and yield. This is also substantiated by the eco-physiological parameters. The soil nutritional and physical parameters favour higher metabolites hydroxyvalerenic acid and valerenic acid accumulation. The study leads to successful plants raising with increased metabolites. The study paves the way forward, overcoming accessional and agro-climatic differences in growth, yield and metabolite, as appropriately monitored potting media help in consistent & optimized yield and metabolites in V. jatamansi.

Comparisons of Rainfall Microphysical Characteristics between the Southeastern Tibetan Plateau and Low-Altitude Areas

Abstract The low air pressure and density over the Tibetan Plateau may have an impact on the microphysical features of rainfall. Using a two-dimensional video disdrometer (2DVD), a Micro Rain Radar (MRR), and a microwave radiometer (MWR), the features of the raindrop size distribution (DSD) on the southeastern Tibetan Plateau (SETP) are explored and compared with those in low-altitude regions. The falling speed of raindrops on the SETP is higher than that in low-altitude areas. Under different rainfall-rate categories, the number concentration and the maximum diameter of raindrops on the SETP are smaller than those in low-altitude regions. The convective rainfall on the SETP is more maritime-like because the South Asian summer monsoon brings water vapor from the ocean here. For stratiform and convective rainfall, the SETP has more small-sized raindrops than low-altitude locations. The mass-weighted mean diameters (Dm) on the SETP are the smallest among six sites. The generalized intercept parameter (Nw) of stratiform rainfall is balanced at a low rainfall rate, while that of convective rainfall is balanced at a high rainfall rate. Furthermore, for a given μ (the shape parameter of gamma distribution) value, the λ (the slope parameter of gamma distribution) value on the SETP is the highest of the six sites. Significance Statement For the occurrence and progression of rainfall, microphysical processes (for instance, collision, fragmentation, coalescence, and evaporation) that take place when rainfall particles descend are crucial. A key factor in the microphysical features of rainfall that varies with rainfall rates and types is the raindrop size distribution (DSD). The southeastern Tibetan Plateau (SETP)’s unique terrain ensures that there is enough moisture for rain to fall there, but little is known about the microphysical aspects of this type of precipitation. There has not been enough research done on how the high altitude affects the microphysical features of rainfall. The microphysical features of rainfall in this area must thus be studied.

The Minimal Impact of Anthropogenic Disturbances on the Spatial Activities of Leopard Cats in Xinlong, China.

The habitat plays a crucial role in ensuring the survival of wildlife. However, the increasing disturbances caused by human activities present a substantial threat to habitats, especially for species such as the leopard cat (Prionailurus bengalensis), which is a significant small predator. Currently, research on leopard cats predominantly focuses on low-altitude regions within its distribution range, leaving plateau areas understudied. To enhance our understanding of the impact of human disturbances on leopard cat habitats, we undertook a study employing infrared camera trappings to monitor leopard cats' activity in Xinlong of southwestern China between 2015 and 2023. We analyzed the spatial distribution and habitat suitability of the leopard cats by utilizing ensemble species distribution models (ESDMs). Moreover, we employed two-species occupancy models to investigate the spatial interaction between leopard cats and human disturbances. The results indicated that (1) the potential suitable habitat area for leopard cats encompassed approximately 1324.93 km2 (14.3%), primarily located along the banks of Yalong river. (2) The distribution of suitable habitat was predominantly influenced by competitors, specifically the yellow-throated marten (YTM), accounting for 52.4% of the influence, as well as environmental factors such as distance to water (DTW) at 12.0% and terrain roughness index (TRI) at 10.0%. Human interference, including cattle presence (4.6%), distance to road (DTD, 4.9%), and distance to settlement (DTS, 3.5%), had a limited impact on the habitat distribution. (3) Within a 5 km radius, habitat suitability increased with proximity to human settlements. (4) Leopard cats exhibited spatial independence from humans and domestic cattle (species interaction factor (SIF) = 1.00) while avoiding domestic horses (SIF = 0.76 ± 0.03). The relatively minor impact of human disturbances in Xinlong could be attributed to traditional cultural practices safeguarding wildlife and the leopard cat's environmental adaptability. We recommend establishing a novel conservation paradigm based on the living dynamics of wildlife communities in Xinlong, thereby offering a more targeted approach to biodiversity preservation in the future.

Analysis of the spatial and temporal distribution characteristics of AOD in typical industrial cities in northwest China and the influence of meteorological factors

The spatiotemporal distribution characteristics of AOD in Lanzhou City over the past decade, as well as the influence of meteorological factors, were analyzed using the MODIS MCD19A2 dataset from 2011 to 2022. Spatial Distribution: The annual average AOD in the study area was found to be 0.278. High AOD values were observed in the main urban area and surrounding low-altitude regions, while low AOD values were observed in the high-altitude mountainous areas in the northwest and southeast. The main urban area exhibited significantly higher AOD levels compared to the three surrounding counties. Temporal Trends: Influenced by air pollution control policies, the AOD in Lanzhou City started decreasing notably from 2014, with a total decrease of −27.18%. The overall trend displayed fluctuations and a downward pattern. The seasonal variation of AOD in Lanzhou City was evident, with the order of magnitude being spring > winter > autumn > summer. The AOD in Yuzhong County was particularly high in spring. There is spatial heterogeneity in the impact of meteorological factors on AOD in Lanzhou. Temperature exhibits greater significance in the central part of Lanzhou, while precipitation shows greater significance in the eastern part of the city, and wind speed is notably significant in the western and eastern parts of Lanzhou. Temperature, relative humidity, and wind speed are positively correlated with AOD, while precipitation and atmospheric pressure are negatively correlated with AOD. Three primary sets of interacting factors were identified: temperature and wind speed, temperature and relative humidity, and temperature and precipitation.

The putatively high-altitude adaptation of macaque monkeys: Evidence from the fecal metabolome and gut microbiome.

Animals living in high-altitude environments, such as the Tibetan Plateau, must face harsh environmental conditions (e.g., hypoxia, cold, and strong UV radiation). These animals' physiological adaptations (e.g., increased red cell production and turnover rate) might also be associated with the gut microbial response. Bilirubin is a component of red blood cell turnover or destruction and is excreted into the intestine and reduced to urobilinoids and/or urobilinogen by gut bacteria. Here, we found that the feces of macaques living in high-altitude regions look significantly browner (with a high concentration of stercobilin, a component from urobilinoids) than those living in low-altitude regions. We also found that gut microbes involved in urobilinogen reduction (e.g., beta-glucuronidase) were enriched in the high-altitude mammal population compared to the low-altitude population. Moreover, the spatial-temporal change in gut microbial function was more profound in the low-altitude macaques than in the high-altitude population, which might be attributed to profound changes in food resources in the low-altitude regions. Therefore, we conclude that a high-altitude environment's stress influences living animals and their symbiotic microbiota.

Evaluating drought monitoring utility of the top-down and bottom-up satellite precipitation products over mainland China from a three-dimensional perspective

Satellite-based quantitative precipitation estimates (QPEs) have shown great potential in the precipitation-related extremes estimation. However, little is known about the capability of different QPEs to monitor the dynamic evolutions of drought on various spatio-temporal scales. Here, the drought utility of two top-down QPEs (i.e., Climate Hazards Group InfraRed Precipitation with Stations, CHIRPS; Integrated Multi-SatellitE Retrievals for Global precipitation measurement-Final run, IMERG-F) and one bottom-up QPE (i.e., Soil Moisture to Rain-Advanced SCATterometer, SM2RAIN-ASCAT), is evaluated comprehensively in mainland China, based on three commonly used drought indices (Standardized Precipitation Index, Standardized Precipitation Evapotranspiration Index, Composite index of meteorological drought). The results indicate that the top-down QPEs generally show better performance in detecting drought occurrence over the humid and low-altitude regions in eastern China than the arid and high-altitude regions in western China. IMERG-F performs best in detecting drought occurrence in the entire mainland China, followed by CHIRPS, and the least satisfactory by SM2RAIN-ASCAT. The trajectory of drought centroids and the temporal variability of drought characteristics are highly dependent on both the drought indices selected and QPEs used. IMERG-F and CHIRPS can better reproduce the trajectories of large-scale drought events (e.g., the locations of drought origin and termination) than SM2RAIN-ASCAT. The ability in tracking the drought centroid trajectory of all three QPEs is higher at the smaller spatial scales, also it improves from the semi-arid to humid regions. Our results highlight the superiority of the top-down QPEs in drought monitoring compared with the bottom-up QPE in mainland China, particularly over the humid regions. The application of SM2RAIN-ASCAT in drought monitoring to the large-scale arid areas should be cautious.

Potential role of the gut microbiota of bumblebee Bombus pyrosoma in adaptation to high-altitude habitats.

The gut microbiota affects the health and overall fitness of bumblebees. It can enhance the host's ecological range by leveraging their metabolic capacities. However, the diversity of the gut microbiota and adaptive functional evolution in high-altitude regions remain unclear. To explore how the gut microbiota helps the host adapt to high-altitude environments, we analyzed the differences in diversity and function of the gut microbiota between high- and low-altitude regions through full-length 16S rRNA sequencing. Our results show that high-altitude regions have a lower abundance of Fructobacillus and Saccharibacter compared to low-altitude regions. Additionally, some individuals in low-altitude regions were invaded by opportunistic pathogens. The gut microbiota in high-altitude regions has a greater number of pathways involved in "Protein digestion and absorption" and "Biosynthesis of amino acids," while fewer carbohydrate pathways are involved in "digestion and absorption" and "Salmonella infection." Our finding suggests that plateau hosts typically reduce energy metabolism and enhance immunity in response to adverse environments. Correspondingly, the gut microbiota also makes changes, such as reducing carbohydrate degradation and increasing protein utilization in response to the host. Additionally, the gut microbiota regulates their abundance and function to help the host adapt to adverse high-altitude environments.

Design and Development of Conical/Contour Nozzle For Slow Burning Solid Booster Operating In Sub-orbital Mission

In order to optimize the performance of the solid booster operating in sub-orbital altitude the contour of the nozzle needs to be tailored. The conventional convergent/divergent nozzle design is either over or under expanding for the altitude of operation. Therefore, minimizing the flow separation and losses is extremely difficult and cumbersome. In this regard, the divergent portion of nozzle plays vital role to attain the maximum performance with suitable design modification. A novel and promising concept of conical and contour nozzle divergent for slow burning propellant motors operating in sub-orbital altitude is designed and being realized for qualification test. Conical and contour nozzle divergent is a viable solution to avoid flow separation during the lower pressure and lower altitude region of the mission. The design arrived as per the mission requirement, has a conical divergent up to 737 mm from throat plane and third order polynomial profile up to exit, which will give a turn back angle of 5°.The injection point of Secondary Injection Thrust Vector Control System (SITVC) of nozzle is chosen at 45% of total distance from throat plane to exit plane. The present study brings out the theretical estimations of a conical/contour nozzle perfromance with a slowest burning solid booster operating at lower altitude, &lt; 35 km. Theoretical Computational Fluid Dynamics (CFD) simulation study is carried out to assess the effect of nozzle profile on the flow transition. The basic design methodology adopted to avoid flow separation and the governing formulations are presented in this paper.

Population divergence in maternal investment and embryo energy use and allocation suggests adaptive responses to cool climates.

The thermal sensitivity of early life stages can play a fundamental role in constraining species distributions. For egg-laying ectotherms, cool temperatures often extend development time and exacerbate developmental energy cost. Despite these costs, egg laying is still observed at high latitudes and altitudes. How embryos overcome the developmental constraints posed by cool climates is crucial knowledge for explaining the persistence of oviparous species in such environments and for understanding thermal adaptation more broadly. Here, we studied maternal investment and embryo energy use and allocation in wall lizards spanning altitudinal regions, as potential mechanisms that enable successful development to hatching in cool climates. Specifically, we compared population-level differences in (1) investment from mothers (egg mass, embryo retention and thyroid yolk hormone concentration), (2) embryo energy expenditure during development, and (3) embryo energy allocation from yolk towards tissue. We found evidence that energy expenditure was greater under cool compared with warm incubation temperatures. Females from relatively cool regions did not compensate for this energetic cost of development by producing larger eggs or increasing thyroid hormone concentration in yolk. Instead, embryos from the high-altitude region used less energy to complete development, that is, they developed faster without a concomitant increase in metabolic rate, compared with those from the low-altitude region. Embryos from high altitudes also allocated relatively more energy towards tissue production, hatching with lower residual yolk: tissue ratios than low-altitude region embryos. These results are consistent with local adaptation to cool climate and suggest that this is underpinned by mechanisms that regulate embryonic utilisation of yolk reserves and its allocation towards tissue, rather than shifts in maternal investment of yolk content or composition.