364 research outputs found

    Salt Content Distribution and Paleoclimatic Significance of the Lop Nur “Ear” Feature: Results from Analysis of EO-1 Hyperion Imagery

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    Lop Nur, a playa lake located on the eastern margin of Tarim Basin in northwestern China, is famous for the “Ear” feature of its salt crust, which appears in remote-sensing images. In this study, partial least squares (PLS) regression was used to estimated Lop Nur playa salt-crust properties, including total salt, Ca2+, Mg2+, Na+, Si2+, and Fe2+ using laboratory hyperspectral data. PLS results for laboratory-measured spectra were compared with those for resampled laboratory spectra with the same spectral resolution as Hyperion using the coefficient of determination (R2) and the ratio of standard deviation of sample chemical concentration to root mean squared error (RPD). Based on R2 and RPD, the results suggest that PLS can predict Ca2+ using Hyperion reflectance spectra. The Ca2+ distribution was compared to the “Ear area” shown in a Landsat Thematic Mapper (TM) 5 image. The mean value of reflectance from visible bands for a 14 km transversal profile to the “Ear area” rings was extracted with the TM 5 image. The reflectance was used to build a correlation with Ca2+ content estimated with PLS using Hyperion. Results show that the correlation between Ca2+ content and reflectance is in accordance with the evolution of the salt lake. Ca2+ content variation was consistent with salt deposition. Some areas show a negative correlation between Ca2+ content and reflectance, indicating that there could have been a small-scale temporary runoff event under an arid environmental background. Further work is needed to determine whether these areas of small-scale runoff are due to natural (climate events) or human factors (upstream channel changes

    Vertical Changes in Soil Physical Structure and Water Flow

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    Previous microplastic research under laboratory conditions has focused on microplastics that are homogeneously mixed into test media, in order to maximize test reproducibility and uniform bio-accessibility. Here we specifically focused on testing the idea that microplastics in soil could affect adjacent soil layers not containing microplastic themselves. We included two different microplastics (low-density polyethylene films and polyacrylonitrile fibers) and carried out a soil column test consisting of three different vertical layers (0–3 cm, top, control soil; 3–6 cm, middle, microplastic-containing soil; 6–9 cm, bottom, control soil). Our study shows that microplastic-containing soil layers can act as an anthropogenic barrier in the soil column, interrupting the vertical water flow. These changes directly affected the water content of adjacent layers, and changes in the proportion of soil aggregate sizes occurred for each depth of the soil columns. We also observed that these physical changes trigger changes in soil respiration, but do not translate to effects on enzyme activities. These results imply that the soil environment in non-contaminated parts of the soil can be altered by microplastic contamination in adjacent layers, as might occur for example during ploughing on agricultural fields. More generally, our results highlight the need to further examine effects of microplastic in experiments that do not treat this kind of pollution as uniformly distributed

    Network structure of emotional and behavioral problems, loneliness, and suicidal thoughts in adolescents at the school closure and reopening stage in China

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    BACKGROUND: Public restriction and school closure policies during the pandemic may have long-term effects on adolescents' mental health, and adolescents' feelings and needs may change as the pandemic progresses. This study was conducted to explore the network structure and differences in emotional and behavioral problems (EBPs), loneliness, and suicidal thoughts in adolescents during different pandemic periods in China. METHODS: Based on two cross-sectional studies conducted in Taizhou, China, during school closure (April 16 to May 14, 2020) and reopening (May 25 to July 10, 2021) using online questionnaire, a total of 14,726 adolescents (school closure: 6,587, school reopening: 8,139) were recruited. EBPs were evaluated based on the student version of the Strengths and Difficulties Questionnaire (SDQ). Loneliness and suicidal thoughts were measured by item 20 and item 9 of the Chinese version of the Children's Depression Inventory (CDI), respectively. Network analysis was used to estimate the network connections and properties between EBPs, loneliness, and suicidal thoughts. RESULTS: The prevalence of psychosocial problems significantly increased at the school reopening compared with the school closure: EBPs: 36.8% vs. 31.6%; loneliness: 40.3% vs. 33.9%; suicidal thoughts: 40.8% vs. 15.4%. Suicidal thoughts showed the closest connections with being unhappy and lonely. Being bullied was strongly connected with conduct problems of lying and stealing. The links between hyperactivity symptoms and the other domains of EBPs were stronger after the school reopened. Being unhappy and showing the hyperactivity symptoms of "nonpersistent, distractible, and fidgety" presented high network and bridge (increasing transference from one symptom domain to another) centrality. Loneliness showed high expected influence and bridge centrality. CONCLUSIONS: This study highlighted the high prevalence of EBPs, loneliness, and suicidal thoughts in Chinese adolescents. It also presented the network structure of these psychological problems over different pandemic stages. It is recommended that psychological support should be provided for adolescents, especially focusing on the central and bridge symptoms highlighted in this study

    Learning from supervisor negative gossip: the reflective learning process and performance outcome of employee receivers

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    Workplace gossip is generally viewed as a deviant behavior that negatively affects the work outcomes of employees. However, we argue that this negative view is incomplete. Drawing on the cultural learning perspective of gossip and social learning theory, we examine how the job performance of employee receivers benefits from supervisor negative gossip through reflective learning. On the basis of multi-source, cross-sectional designs, Studies 1 and 2 consistently find that supervisor negative gossip facilitates employee receiver reflective learning and subsequent job performance when controlling for two sets of theory-relevant variables. Study 3, which has a multi-source, cross-lagged panel design, provides further evidence of the directional relationship from supervisor negative gossip to employee receiver job performance through reflective learning. The findings of the three separate field studies support the positive effect of supervisor negative gossip on employee receivers from a learning perspective. We discuss the theoretical and practical implications of these findings in terms of how employee receiver job performance can benefit from workplace negative gossip

    Poly[(μ-1H-benzimidazole-5,6-dicarboxyl­ato)lead(II)]

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    The crystal structure of the two-dimensional polymeric title compound, [Pb(C9H4N2O4)]n, comprises one crystallo­graphic­ally independent PbII atom and one fully deprotonated 1H-benzimidazole-5,6-dicarboxyl­ate (H2 L) ligand. The PbII atom is seven-coordinated by six O atoms and one N atom from the H2 L ligands, giving a capped octa­hedral coordination geometry. The structure is a layered two-dimensional coordination polymer extending parallel to (100) with N—H⋯O hydrogen bonds inter­actions between the layers, stabilizing the crystal structure

    A Miniaturize Bandpass Filter with Harmonic Suppression Using Meandered Quarter-Wavelength Resonators

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    A miniaturized bandpass filter with harmonics suppression is presented. The proposed filter consists of two quarter-wavelength microstrip resonators, which are meandered for circuit size reduction. An interdigital capacitor, loading at zero-voltage point, is employed to provide the desired coupling between the resonators at operating frequency, whereas the coupling coefficient at the third harmonic is realized to be zero. Besides, the second and fourth harmonics are suppressed since λ/4 resonators are adopted. Benefiting from these properties, a miniaturized bandpass filter with the second, third, and fourth harmonics suppression was designed and implemented. The final measured and simulated results show good consistence with the theoretical counterparts
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