8,756 research outputs found

    Geochronology and geochemistry of the c. 80 Ma Rutog granitic pluton, northwestern Tibet: Implications for the tectonic evolution of the Lhasa Terrane

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    The Rutog granitic pluton lies in the Gangdese magmatic arc in the westernmost part of the Lhasa Terrane, NW Tibet, and has SHRIMP zircon U-Pb ages of c. 80 Ma. The pluton consists of granodiorite and monzogranite with SiO2 ranging from 62 to 72 wt% and Al2 O3 from 15 to 17 wt%. The rocks contain 2.33-4.93 wt% K2O and 3.42-5.52 wt% Na2O and have Na2O/K2O ratios of 0.74-2.00. Their chondrite-normalized rare earth element (REE) patterns are enriched in LREE ((La/Yb)n = 15 to 26) and do not show significant Eu anomalies (αEu = 0.68-1.15). On a primitive mantle-normalized trace element diagram, the rocks are rich in large ion lithophile elements (LILE) and poor in high field strength elements (HFSE), HREE and Y. Their Sr/Y ratios range from 15 to 78 with an average of 30. The rocks have constant initial 87Sr/86Sr ratios (0.7045 to 0.7049) and slightly positive εNd(t) values (+0.1 to +2.3), similar to I-type granites generated in an arc setting. The geochemistry of the Rutog pluton is best explained by partial melting of a thickened continental crust, triggered by underplating of basaltic magmas in a mantle wedge. The formation of the Rutog pluton suggests flat subduction of the Neo-Tethyan oceanic lithosphere from the south. Crustal thickening may have occurred in the Late Cretaceous prior to the India-Asia collision. © Cambridge University Press 2008.published_or_final_versio

    Working Memory Modulation of Frontoparietal Network Connectivity in First-Episode Schizophrenia

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    Working memory (WM) impairment is regarded as a core aspect of schizophrenia. However, the neural mechanisms behind this cognitive deficit remain unclear. The connectivity of a frontoparietal network is known to be important for subserving WM. Using functional magnetic resonance imaging, the current study investigated whether WM-dependent modulation of effective connectivity in this network is affected in a group of first-episode schizophrenia (FES) patients compared with similarly performing healthy participants during a verbal n-back task. Dynamic causal modeling (DCM) of the coupling between regions (left inferior frontal gyrus (IFG), left inferior parietal lobe (IPL), and primary visual area) identified in a psychophysiological interaction (PPI) analysis was performed to characterize effective connectivity during the n-back task. The PPI analysis revealed that the connectivity between the left IFG and left IPL was modulated by WM and that this modulation was reduced in FES patients. The subsequent DCM analysis confirmed this modulation by WM and found evidence that FES patients had reduced forward connectivity from IPL to IFG. These findings provide evidence for impaired WM modulation of frontoparietal effective connectivity in the early phase of schizophrenia, even with intact WM performance, suggesting a failure of context-sensitive coupling in the schizophrenic brain

    Detecting Communities with Different Sizes for Social Network Analysis

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    National Natural Science Foundation of China; Yunnan Educational Department Foundation; Program for Young and Middle-aged Skeleton Teachers, Yunnan Universit

    Adolescent Motherhood and HIV in South Africa: Examining Prevalence of Common Mental Disorder

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    The mental health of adolescents (10–19 years) remains an overlooked global health issue, particularly within the context of syndemic conditions such as HIV and pregnancy. Rates of pregnancy and HIV among adolescents within South Africa are some of the highest in the world. Experiencing pregnancy and living with HIV during adolescence have both been found to be associated with poor mental health within separate explorations. Yet, examinations of mental health among adolescents living with HIV who have experienced pregnancy/parenthood remain absent from the literature. As such, there exists no evidence-based policy or programming relating to mental health for this group. These analyses aim to identify the prevalence of probable common mental disorder among adolescent mothers and, among adolescents experiencing the syndemic of motherhood and HIV. Analyses utilise data from interviews undertaken with 723 female adolescents drawn from a prospective longitudinal cohort study of adolescents living with HIV (n = 1059) and a comparison group of adolescents without HIV (n = 467) undertaken within the Eastern Cape Province, South Africa. Detailed study questionnaires included validated and study specific measures relating to HIV, adolescent motherhood, and mental health. Four self-reported measures of mental health (depressive, anxiety, posttraumatic stress, and suicidality symptomology) were used to explore the concept of likely common mental disorder and mental health comorbidities (experiencing two or more common mental disorders concurrently). Chi-square tests (Fisher’s exact test, where appropriate) and Kruskal Wallis tests were used to assess differences in sample characteristics (inclusive of mental health status) according to HIV status and motherhood status. Logistic regression models were used to explore the cross-sectional associations between combined motherhood and HIV status and, likely common mental disorder/mental health comorbidities. 70.5% of participants were living with HIV and 15.2% were mothers. 8.4% were mothers living with HIV. A tenth (10.9%) of the sample were classified as reporting a probable common mental disorder and 2.8% as experiencing likely mental health comorbidities. Three core findings emerge: (1) poor mental health was elevated among adolescent mothers compared to never pregnant adolescents (measures of likely common mental disorder, mental health comorbidities, depressive, anxiety and suicidality symptoms), (2) prevalence of probable common mental disorder was highest among mothers living with HIV (23.0%) compared to other groups (Range:8.5–12.8%; Χ2 = 12.54, p = 0.006) and, (3) prevalence of probable mental health comorbidities was higher among mothers, regardless of HIV status (HIV & motherhood = 8.2%, No HIV & motherhood = 8.2%, Χ2 = 14.5, p = 0.002). Results identify higher mental health burden among adolescent mothers compared to never-pregnant adolescents, an increased prevalence of mental health burden among adolescent mothers living with HIV compared to other groups, and an elevated prevalence of mental health comorbidities among adolescent mothers irrespective of HIV status. These findings address a critical evidence gap, highlighting the commonality of mental health burden within the context of adolescent motherhood and HIV within South Africa as well as the urgent need for support and further research to ensure effective evidence-based programming is made available for this group. Existing antenatal, postnatal, and HIV care may provide an opportunity for mental health screening, monitoring, and referral

    A keystone microbial enzyme for nitrogen control of soil carbon storage

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    This is the final version. Available on open access from AAAS via the DOI in this recordData and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials and figshare (https://figshare.com/s/37aa98b76a7ef51da2e2). Correspondence should be addressed to Y.L. ([email protected]). Requests for additional materials and database should be addressed to J. Cao ([email protected]), R.-w.W. ([email protected]), and X.Z. ([email protected]).Agricultural and industrial activities have increased atmospheric nitrogen (N) deposition to ecosystems worldwide. N deposition can stimulate plant growth and soil carbon (C) input, enhancing soil C storage. Changes in microbial decomposition could also influence soil C storage, yet this influence has been difficult to discern, partly because of the variable effects of added N on the microbial enzymes involved. We show, using meta-analysis, that added N reduced the activity of lignin-modifying enzymes (LMEs), and that this N-induced enzyme suppression was associated with increases in soil C. In contrast, N-induced changes in cellulase activity were unrelated to changes in soil C. Moreover, the effects of added soil N on LME activity accounted for more of the variation in responses of soil C than a wide range of other environmental and experimental factors. Our results suggest that, through responses of a single enzyme system to added N, soil microorganisms drive long-term changes in soil C accumulation. Incorporating this microbial influence on ecosystem biogeochemistry into Earth system models could improve predictions of ecosystem C dynamics.Fundamental Research Funds for the Central Universitiesational Natural Science Foundation of China (NSFC)China Postdoctoral Science FoundationNatural Science Basic Research Plan in Shaanxi ProvinceState Key Laboratory of Loess and Quaternary GeologyKey Laboratory of Aerosol Chemistry and PhysicsInstitute of Earth Environment, Chinese Academy of SciencesUS Department of EnergyNSFNSFC-Yunnan United FundNational Science Fund for Distinguished Young ScholarsChina Scholarship Counci

    Three-dimensionally Ordered Macroporous Structure Enabled Nanothermite Membrane of Mn2O3/Al

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    Mn2O3 has been selected to realize nanothermite membrane for the first time in the literature. Mn2O3/Al nanothermite has been synthesized by magnetron sputtering a layer of Al film onto three-dimensionally ordered macroporous (3DOM) Mn2O3 skeleton. The energy release is significantly enhanced owing to the unusual 3DOM structure, which ensures Al and Mn2O3 to integrate compactly in nanoscale and greatly increase effective contact area. The morphology and DSC curve of the nanothermite membrane have been investigated at various aluminizing times. At the optimized aluminizing time of 30 min, energy release reaches a maximum of 2.09 kJ∙g−1, where the Al layer thickness plays a decisive role in the total energy release. This method possesses advantages of high compatibility with MEMS and can be applied to other nanothermite systems easily, which will make great contribution to little-known nanothermite research

    Transition Metal Migration Can Facilitate Ionic Diffusion in Defect Garnet-Based Intercalation Electrodes

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    The importance of metal migration during multielectron redox activity has been characterized, revealing a competing demand to satisfy bonding requirements and local strains in structures upon alkali intercalation. The local structural evolution required to accommodate intercalation in Y2(MoO4)3 and Al2(MoO4)3 has been contrasted by operando characterization methods, including X-ray absorption spectroscopy and diffraction, along with nuclear magnetic resonance measurements. Computational modeling further rationalized behavioral differences. The local structure of Y2(MoO4)3 was maintained upon lithiation, while the structure of Al2(MoO4)3 underwent substantial local atomic rearrangements as the more ionic character of the bonds in Al2(MoO4)3 allowed Al to mix off its starting octahedral position to accommodate strain during cycling. However, this mixing was prevented in the more covalent Y2(MoO4)3, which accommodated strain through rotational motion of polyhedral subunits. Knowing that an increased ionic character can facilitate the diffusion of redox-inactive metals when cycling multielectron electrodes offers a powerful design principle when identifying next-generation intercalation hosts
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