Suicidal Plans and Attempts Among Adolescents in Mongolia: Urban Versus Rural Differences

Background: Although 75% of suicides occur in low- and middle-income countries, few studies have examined suicidal behaviors among young people in these countries. Aims: This study aimed to examine what individual characteristics were associated with suicidal plans and attempts among Mongolian youth and whether suicidal risks and behaviors varied by urban and rural locations. Method: Logistic regression analyses were utilized to investigate suicidal plans and attempts among 5,393 adolescents using the Global Student Health Survey – 2013. Results: Adolescents who lived in urban areas were at higher risk for suicidal plans and behaviors than those who lived in rural areas; however, the patterns of suicidal risks were similar. Specifically, individual characteristics, such as being female, feeling lonely and worried, smoking cigarettes, drinking alcohol, and having fights at school, were associated with suicidal plans and behaviors regardless of the residential places. Limitations: A number of important variables have not been included in the questionnaire such as depression, family and parental support, household income, family constructs etc. Conclusion: Given the comparable patterns of risk between urban and rural adolescents and the relatively high rates of suicidal plans and attempts, similar mental health services and interventions are necessitated for both urban and rural areas

Linking coarse silt production in Asian sand deserts and Quaternary accretion of the Chinese Loess Plateau

The Chinese Loess Plateau (CLP) is a large, spatially well defined and persistent zone of loess accumulation developed near the fluctuating northwest margin of the East Asian monsoon. Many studies have analyzed its loess sediments to provide insights into paleoclimatic conditions. Although spatial and temporal variations in the grain sizes of CLP sediments are fundamental to this effort, controversy over the origin of the dominant coarse quartz silt has limited interpretations. Reexamination of the spatial pattern of grain-size distribution across the CLP and a field-scale experiment conducted in the Gobi Desert revealed a genetic association between the coarse silt fraction of the loess and primary production of coarse silt through eolian abrasion of sand in the proximal Mu-Us, Tengger, and Badain Jaran sandy deserts. Our results demonstrate the effectiveness of eolian abrasion of quartz sand in primary coarse silt production in Central Asia and identify this process as the most consistent with the wellrecognized systematic northwest-southeast depositional pattern of the CLP. We suggest that only abraded coarse quartz grains transported short distances by long-term persistent eolian activity can build up thick loess sequences to form a massive and spatially well defined loess plateau. These results decouple the production and transport of coarse silt and finer silt and clay particles, which have a more distant and wider provenance, changing the constraints on previous paleoclimatic reconstructions. © 2013 Geological Society of America

Linking coarse silt production in asian sand deserts and quaternary accretion of the Chinese Loess Plateau

The Chinese Loess Plateau (CLP) is a large, spatially well defined and persistent zone of loess accumulation developed near the fluctuating northwest margin of the East Asian monsoon. Many studies have analyzed its loess sediments to provide insights into paleoclimatic conditions. Although spatial and temporal variations in the grain sizes of CLP sediments are fundamental to this effort, controversy over the origin of the dominant coarse quartz silt has limited interpretations. Reexamination of the spatial pattern of grain-size distribution across the CLP and a field-scale experiment conducted in the Gobi Desert revealed a genetic association between the coarse silt fraction of the loess and primary production of coarse silt through eolian abrasion of sand in the proximal Mu-Us, Tengger, and Badain Jaran sandy deserts. Our results demonstrate the effectiveness of eolian abrasion of quartz sand in primary coarse silt production in Central Asia and identify this process as the most consistent with the well-recognized systematic northwest-southeast depositional pattern of the CLP. We suggest that only abraded coarse quartz grains transported short distances by long-term persistent eolian activity can build up thick loess sequences to form a massive and spatially well defined loess plateau. These results decouple the production and transport of coarse silt and finer silt and clay particles, which have a more distant and wider provenance, changing the constraints on previous paleoclimatic reconstructions.</p

Validation of ASTER Emissivity Retrieval Using the Mako Airborne TIR Imaging Spectrometer at the Algodones Dune Field in Southern California, USA

Validation of emissivity (&epsilon;) retrievals from spaceborne thermal infrared (TIR) sensors typically requires spatial extrapolations over several orders of magnitude for a comparison between centimeter-scale laboratory &epsilon; measurements and the common decameter and lower resolution of spaceborne TIR data. In the case of NASA&rsquo;s Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) temperature and &epsilon; separation algorithm (TES), this extrapolation becomes especially challenging because TES was originally designed for the geologic surface of Earth, which is typically heterogeneous even at centimeter and decameter scales. Here, we used the airborne TIR hyperspectral Mako sensor with its 2.2 m/pixel resolution, to bridge this scaling issue and robustly link between ASTER TES 90 m/pixel emissivity retrievals and laboratory &epsilon; measurements from the Algodones dune field in southern California, USA. The experimental setup included: (i) Laboratory XRD, grain size, and TIR spectral measurements; (ii) radiosonde launches at the time of the two Mako overpasses for atmospheric corrections; (iii) ground-based thermal measurements for calibration, and (iv) analyses of ASTER day and night &epsilon; retrievals from 21 different acquisitions. We show that while cavity radiation leads to a 2% to 4% decrease in the effective emissivity contrast of fully resolved scene elements (e.g., slipface slopes and interdune flats), spectral variability of the site when imaged at 90 m/pixel is below 1%, because at this scale the dune field becomes an effectively homogeneous mixture of the different dune elements. We also found that adsorption of atmospheric moisture to grain surfaces during the predawn hours increased the effective &epsilon; of the dune surface by up to 0.04. The accuracy of ASTER&rsquo;s daytime emissivity retrievals using each of the three available atmospheric correction protocols was better than 0.01 and within the target performance of ASTER&rsquo;s standard emissivity product. Nighttime emissivity retrievals had lower precision (&lt;0.03) likely due to residual atmospheric effects. The water vapor scaling (WVS) atmospheric correction protocol was required to obtain accurate (&lt;0.01) nighttime ASTER emissivity retrievals