The Cloud-AerosoL InteractionS in the Helmos background TropOsphere (CALISHTO) campaign took place in autumn 2021 at the NCSR Demokritos background high-altitude Helmos Hellenic Atmospheric Aerosol ...and Climate Change station (HAC).sup.2 to study the interactions between aerosols and clouds. The current study presents the chemical characterization of the non-refractory (NR) PM.sub.1 aerosol fraction using a time-of-flight aerosol chemical speciation monitor (ToF-ACSM). A comparative offline aerosol filter analysis by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) showed consistent results regarding the species determined. Source apportionment applied on both datasets (ACSM-ToF and offline AMS analysis on filter extracts) yielded the same factors for the organic aerosol (one primary and two secondary factors). Additionally, the positive matrix factorization (PMF) model was applied on the total PM.sub.1 fraction by the ToF-ACSM (including both organic and inorganic ions). Five different types were identified, including a primary organic factor; ammonium nitrate; ammonium sulfate; and two secondary organic aerosols, one more oxidized and one less oxidized. The prevailing atmospheric conditions at the station, i.e., cloud presence, influence of emissions from the planetary boundary layer (PBL), and air mass origin, were also incorporated in the study. The segregation between PBL and free-troposphere (FT) conditions was made by combining data from remote sensing and in situ measurement techniques. The types of air masses arriving at the site were grouped as continental, marine, dust, and marine-dust based on back-trajectory data. Significant temporal variability in the aerosol characteristics was observed throughout the campaign; in September, air masses from within the PBL were sampled most of the time, resulting in much higher mass concentrations compared to October and November when concentrations were reduced by a factor of 5. Both in-cloud and FT measurement periods resulted in much lower concentration levels, while a similar composition was observed in PBL and FT conditions. We take advantage of using a recently developed "virtual-filtering" technique to separate interstitial from activated aerosol sampled from a PM.sub.10 inlet during cloudy periods. This allows the determination of the chemical composition of the interstitial aerosol during in-cloud periods. Ammonium sulfate, the dominant PMF factor in all conditions, contributed more when air masses were arriving at (HAC).sup.2 during dust events, while a higher secondary organic aerosol contribution was observed when air masses arrived from continental Europe.
Mobile edge computing (MEC) is an emerging technology to support resource-intensive yet delay-sensitive applications using small cloud-computing platforms deployed at the mobile network edges. ...However, the existing MEC techniques are not applicable to the situation where the number of mobile users increases explosively or the network facilities are sparely distributed. In view of this insufficiency, unmanned aerial vehicles (UAVs) have been employed to improve the connectivity of ground Internet-of-Things (IoT) devices due to their high altitude. This paper proposes an innovative UAV-enabled MEC system involving the interactions among IoT devices, UAV and edge clouds (ECs). The system deploys and operates a UAV properly to facilitate the MEC service provisioning to a set of IoT devices in regions where existing ECs cannot be accessible to IoT devices due to terrestrial signal blockage or shadowing. The UAV and ECs in the system collaboratively provide MEC services to the IoT devices. For optimal service provisioning in this system, we formulate an optimization problem aiming at minimizing the weighted sum of the service delay of all IoT devices and UAV energy consumption by jointly optimizing UAV position, communication and computing resource allocation, and task splitting decisions. However, the resulting optimization problem is highly non-convex and thus difficult to solve optimally. To tackle this problem, we develop an efficient algorithm based on successive convex approximation to obtain sub-optimal solutions. Numerical experiments demonstrate that our proposed collaborative UAV-EC offloading scheme largely outperforms baseline schemes that solely rely on UAV or edge clouds for MEC in IoT.
Soil fungi often operate through diverse functional guilds, and play critical roles in driving soil nutrient cycling, organic matter decomposition and the health of above-ground vegetation. However, ...fungal functional guilds at the early-stage restoration of disrupted subalpine forest soils remain elusive. In the present study, we collected 36 soil samples along an altitudinal gradient (2900 m a.s.l., 3102 m a.s.l., and 3194 m a.s.l.) from cut slopes (CS) (from Wenma highway) and natural soils (NS) at the Miyaluo of Lixian County, Southwest China. By applying nuclear ribosomal internal transcribed spacer (ITS) sequencing, this study revealed the ecological characteristics of fungal functional guild in the early-stage restoration of cut slope soils. The results showed that the predicted prevalence of ectomycorrhizal fungi decreased, while plant pathogens and arbuscular mycorrhizal fungi increased in CS. In the high-altitude regions (3102 m a.s.l. and 3194 m a.s.l.), the differences in communities between natural and cut slope soils were more pronounced for total soil fungi, soil saprotroph, litter saprotroph, arbuscular mycorrhizal fungi and ectomycorrhizal fungi, in contrast to the low altitude communities (2900 m a.s.l.). An opposite pattern was evident for plant pathogens. Variations in the differences of both soil properties (mainly soil pH) and community assembling processes (e.g., heterogeneous selection, dispersal limitation and drift) between natural and cut slope soils across the altitudinal gradient likely shaped the shifting patterns of community difference. This study provides valuable insights for devising restoration approaches for cut slopes in subalpine forest ecosystems, emphasizing the importance of taking soil fungal functional guilds into account in evaluating the restoration of cut slopes, and underscoring the necessity for increased attention to the restoration of soil fungi in cut slopes at the high-altitude ecosystems.
High altitude cerebral edema (HACE) is a high altitude malady caused by acute hypobaric hypoxia (AHH), in which pathogenesis is associated with oxidative stress and inflammatory cytokines. Potentilla ...anserina L is mainly distributed in Tibetan Plateau, and its polysaccharide possesses many physiological and pharmacological properties. In the present study, the protective effect and potential treatment mechanism of Potentilla anserina L polysaccharide (PAP) in HACE were explored. First, we measured the brain water content and observed the pathological changes in brain tissues, furthermore, malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), and glutathione (GSH) were evaluated by kits. Finally, the protein contents and mRNA expressions of pro‐inflammatory (IL‐1β, IL‐6, TNF‐α, vascular endothelial cell growth factor VEGF, NF‐κB, and hypoxia inducible factor‐1 α HIF‐1α) were detected by ELISA kits, RT‐PCR, and western blotting. The results demonstrated that PAP reduced the brain water content, alleviated brain tissue injury, reduce the levels of MDA and NO, and increased the activity of SOD and GSH level. In addition, PAP blocking the NF‐κB and HIF‐1α signaling pathway activation inhibited the generation of downstream pro‐inflammatory cytokines (IL‐1β, IL‐6, TNF‐α, and VEGF). Therefore, PAP has a potential to treat and prevent of HACE by suppression of oxidative stress and inflammatory response.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Exploring plant trait variance within a species that is naturally distributed along an environmental gradient is key to understanding plant acclimation strategies. Here, we investigated plant trait ...variance of
Sophora moorcroftiana
in the Qinghai–Tibet Plateau along an altitudinal gradient. The results showed that plant traits changed from acquisitive to conservative resource use strategy from low to high altitudes. Site-specific trait variance increased along with altitude increase and was strongly correlated with temperature variables, especially closely correlated with minimum temperature in the coldest month. The decreased trends of acquisitive traits and the increase of site-specific trait variance were coordinated with increased
S. moorcroftiana
dominance in high altitudes. The findings provided insight that the combination of plant resource use strategy and site-specific trait variance contributes to
S. moorcroftiana
dominance in response to divergent environmental conditions along altitudinal gradients. The strong correlation between plant trait variance and the minimum temperature in the coldest month suggested that it should pay more attention to the critical role extreme temperature played on trait variance which was often neglected in the past.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This article focuses on the crisis of precarious work/livelihoods that pervades the global tourism industry and prevents many from experiencing fair and just employment. Drawing on an ethnographic ...study of high-altitude mountaineering tourism in the Himalaya, we explore the various ways in which mountain workers are precarious, vulnerable, marginalised and often overlooked in the context of cross-border tourism practices. Drawing on concepts of justice and fairness we argue that the ongoing racial and social contours of colonialism give privileges to some bodies and not "Others," entrenching precarity of vulnerable communities and workers. However, despite these unfavourable conditions, local workers are not without agency to shape their conditions and experiences. Mountain workers on Everest provide an example of how, despite their precarity, workers can self-organise and exercise their voice to secure more just and equitable work. Decent work, secure livelihoods, and equality are core features of the sustainable development goals and will only be achieved through collective action, solidarity from different tourism stakeholders and the realisation of fair and just employment practices for the most vulnerable communities.
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Mountain freshwater communities are generally considered sensible to accelerated climatic changes, though their vulnerabilities have not been well evaluated. Individual species or species groups are ...expected to respond differently depending on their adaptations, traits, or distributions, but this has not yet been distinguished. This work used available climate change vulnerability scores (ccvs) of European Ephemeroptera, Plecoptera, and Trichoptera (EPT) species (n = 1,402) to (1) compare the vulnerability between species pools of different ecoregions including alpine species and alpine endemics, (2) contrast the vulnerability between the different insect orders, and (3) assess the altitude-vulnerability relationship within the European Alps. We revealed fifty alpine Plecoptera and Trichoptera species that are categorized highly vulnerable to climate change effects (= 31 percent of all highly vulnerable European species) with the highest proportions in species inventories of alpine endemics and high-altitude waters (51 percent of high-altitude species are classified as highly vulnerable). The ccvs analysis specifically for mountain waters shows that a disproportionately high number of alpine species, and particularly alpine endemics, will be affected by climate change and suggests that Ephemeroptera may be better prepared than Plecoptera and Trichoptera. Thus, this trait-based evaluation suggests that mountain stream invertebrate communities are undergoing disproportionate restructurings in response to climate change effects more than lowland communities are.
Tropical high‐Andean wetlands, locally known as ‘bofedales’, are key ecosystems sustaining biodiversity, carbon sequestration, water provision and livestock farming. Bofedales' contribution to dry ...season baseflows and sustaining water quality is crucial for downstream water security. The sensitivity of bofedales to climatic and anthropogenic disturbances is therefore of growing concern for watershed management. This study aims to understand seasonal water storage and release characteristics of bofedales by combining remote sensing analysis and ground‐based monitoring for the wet and dry seasons of late 2019 to early 2021, using the glacierised Vilcanota‐Urubamba basin (Southern Peru) as a case study. A network of five ultrasound loggers was installed to obtain discharge and water table data from bofedal sites across two headwater catchments. The seasonal extent of bofedales was mapped by applying a supervised machine learning model using Random Forest on imagery from Sentinel‐2 and NASADEM. We identified high seasonal variability in bofedal area with a total of 3.5% and 10.6% of each catchment area, respectively, at the end of the dry season (2020), which increased to 15.1% and 16.9%, respectively, at the end of the following wet season (2021). The hydrological observations and bofedal maps were combined into a hydrological conceptual model to estimate the storage and release characteristics of the bofedales, and their contribution to runoff at the catchment scale. Estimated lag times between 1 and 32 days indicate a prolonged bofedal flow contribution throughout the dry season (about 74% of total flow). Thus, our results suggest that bofedales provide substantial contribution to dry season baseflow, water flow regulation and storage. These findings highlight the importance of including bofedales in local water management strategies and adaptation interventions including nature‐based solutions that seek to support long‐term water security in seasonally dry and rapidly changing Andean catchments.
A hydrological model of tropical high‐Andean wetland dominated headwaters has been built that disaggregates the contribution of different end members (glacier melt, surface runoff, and wetland and hillslope subsurface flow) to explore and quantify their seasonal dynamics. Results indicate high wetland contributions that are sustained long into the dry season. This highlights their importance for seasonal buffering of water supply and their relevance in local water management.
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A unique book with systematic and thorough coverage of HAP related issues, problems and solutions. Handbook of Broadband Communications from High Altitude Platformsprovides a thorough overview and ...state of the art of the HAP enabling technologies, as well as describing recent research activities with most promising results. It outlines the roadmap for future development of HAPs. Focuses on placing HAPs in the perspective of current and future broadband wireless communication systems, providing the readers with an overview of the constraints affecting HAP-based broadband communicationsProvides a thorough overview of HAP enabling technologies, describes recent research activities with most promising results, and outlines the roadmap for future development of HAPsCovers enabling technologies and economics of HAP-based communication system including issues related to aeronautics, energetics, operating scenarios, applications and business modelingExamines the operating environment, advanced communication techniques for efficient radio link resource management, and suitable antennasAddresses multiplatform constellations, presenting the multiple HAP constellation planning procedure and discussing the networking implications of using multiple HAPs
En las tierras altas de Costa Rica existen formaciones ecológicas que han sido poco estudiadas como el páramo y las turberas. Las turberas en Costa Rica se ubican mayormente en el Parque Nacional ...Tapantí-Macizo de la Muerte en la Cordillera de Talamanca. El objetivo de esta investigación fue caracterizar la vegetación y el suelo de las turberas de altura con el fin de aportar información científica sobre estos ecosistemas para futuras investigaciones. Se tomaron muestras de suelo en cuatro turberas (T1, T2, T3 y T4) a diferentes profundidades (20, 30 y 60 cm), en un gradiente que van desde los 2400 a 3100 m de altitud. Se realizaron análisis físicos y químicos del suelo en el laboratorio del CIA-UCR y se describió la vegetación de las turberas. Los suelos en las turberas corresponden al orden histosol con una textura franco-arenosa, que predominan en zonas frías y pantanosas. El porcentaje de carbono y materia orgánica fue alto en la T3 con 32.90 y 47.05% respectivamente, mientras que la relación C/N fue mayor en T1 con una relación de 22.3%. Los sitios con mayor similitud fueron T2 y T4 en un 99%. La caracterización de la vegetación estuvo representada por plantas vasculares, briófitos en especial del género Sphagnum y líquenes que contribuyen a la formación del suelo turboso. Las turberas son eficientes en acumular carbono en el suelo debido a la materia orgánica que se acumula. La falta de estudios dificulta la comparación de los resultados de este estudio. Se espera que esta investigación sea un aporte valioso para la ciencia, y para consolidar la conservación de la poca extensión de turberas de altura con las que cuenta el país.
