1,336 research outputs found

    Irrigation-Induced Environmental Changes around the Aral Sea: An Integrated View from Multiple Satellite Observations

    Get PDF
    The Aral Sea basin (ASB) is one of the most environmentally vulnerable regions to climate change and human activities. During the past 60 years, irrigation has greatly changed the water distribution and caused severe environmental issues in the ASB. Using remote sensing data, this study investigated the environmental changes induced by irrigation activities in this region. The results show that, in the past decade, land water storage has significantly increased in the irrigated upstream regions (13 km 3 year -1 ) but decreased in the downstream regions (-27 km 3 year -1 ) of the Amu Darya River basin, causing a water storage decrease in the whole basin (-20 km 3 year -1 ). As a result, the water surface area of the Aral Sea has decreased from 32,000 in 2000 to 10,000 km2 in 2015. The shrinking Aral Sea exposed a large portion of the lake bottom to the air, increasing (decreasing) the daytime (nighttime) temperatures by about 1 °C year -1 (0.5 °C year -1 ). Moreover, there were other potential environmental changes, including drier soil, less vegetation, decreasing cloud and precipitation, and more severe and frequent dust storms. Possible biases in the remote sensing data due to the neglect of the shrinking water surface area of the Aral Sea were identified. These findings highlight the severe environmental threats caused by irrigation in Central Asia and call attention to sustainable water use in such dryland regions. Keywords: environmental issues; the shrinking Aral Sea; irrigation; desertification; dust storm; remote sensing; NDVI; GRACE; MODI

    TRUSS STRUCTURE OPTIMIZATION BASED ON IMPROVED WOLF PACK ALGORITHM

    Get PDF
    Aiming at the optimization of truss structure, a wolf pack algorithm based on chaos and improved search strategy was proposed. The mathematical model of truss optimization was constructed, and the classical truss structure was optimized. The results were compared with those of other optimization algorithms. When selecting and updating the initial position of wolves, chaos idea was used to distribute the initial value evenly in the solution space; phase factor was introduced to optimize the formula of wolf detection; information interaction between wolves is increased and the number of runs is reduced. The numerical results show that the improved wolf pack algorithm has the characteristics of fewer parameters, simple programming, easy implementation, fast convergence speed, and can quickly find the optimal solution. It is suitable for the optimization design of the section size of space truss structures

    Irrigation-Induced Environmental Changes around the Aral Sea: An Integrated View from Multiple Satellite Observations

    Get PDF
    The Aral Sea basin (ASB) is one of the most environmentally vulnerable regions to climate change and human activities. During the past 60 years, irrigation has greatly changed the water distribution and caused severe environmental issues in the ASB. Using remote sensing data, this study investigated the environmental changes induced by irrigation activities in this region. The results show that, in the past decade, land water storage has significantly increased in the irrigated upstream regions (13 km3 year−1) but decreased in the downstream regions (−27 km3 year−1) of the Amu Darya River basin, causing a water storage decrease in the whole basin (−20 km3 year−1). As a result, the water surface area of the Aral Sea has decreased from 32,000 in 2000 to 10,000 km2 in 2015. The shrinking Aral Sea exposed a large portion of the lake bottom to the air, increasing (decreasing) the daytime (nighttime) temperatures by about 1 °C year−1 (0.5 °C year−1). Moreover, there were other potential environmental changes, including drier soil, less vegetation, decreasing cloud and precipitation, and more severe and frequent dust storms. Possible biases in the remote sensing data due to the neglect of the shrinking water surface area of the Aral Sea were identified. These findings highlight the severe environmental threats caused by irrigation in Central Asia and call attention to sustainable water use in such dryland regions

    Early development of the Amur sleeper (Perccottus glenii, Dybowski, 1877): a remarkable invasive species in Eurasia

    Get PDF
    To investigate the ontogeny of Perccottus glenii, embryonic, larval and juvenile development of P. glenii were examined under captive condition. The fertilized eggs with numerous oil droplets were orange-pink in color, prolate spherical in shape and had average length of 3.32±0.14 mm and width of 1.24±0.04 mm. From fertilization to hatching, the ontogenesis of the fish spent more than 200 h, and the process of embryonic development was divided into 25 stages based on the morphological characteristics. The newly hatched larvae, with well-developed swim bladder and pectoral fins, measured 5.07±0.18mm in total length. Initial feeding occurred at day 2 after hatching (AH) and the complete absorption of yolk sphere was observed 3 days after hatching. At day 40 AH, scales and vertical pigment were found to be appear. Scales covered the entire body and all fins were well developed 70 days AH, at which time the juveniles reached the young stage with a total length (TL) of 24.74±4.28 mm. At day 140 AH, The fry with a TL of 29.57±4.65 mm, were morphologically similar to the adults except for size

    Expression and Localization of Stanniocalcin-1 in Bovine Osteoblasts

    Get PDF
    As a novel glycoprotein hormone, Stanniocalcin-1 (STC-1) was first identified in teleost species, and it is involved in the regulation of mineral homeostasis in bony fish and mammals. STC-1 can not only affect the mammals bone development, but also protect neurons from the damage of ischemia, and stimulate the angiogenic response. Although it is widely expressed in rodent skeletons, whether this hormone is expressed in the skeleton of ruminant animals, like bovines, is still unknown. Here, we investigated the expression of STC-1 in bovine osteoblasts by using immunocytochemical staining and RT-PCR. Our results show that the mRNA and protein of STC-1 are expressed in the bovine osteoblasts during later differentiation periods 10th day in vitro. The present data support the notion that STC-1 may play a role in the process of bovine bone development
    • 

    corecore