358 research outputs found

    Educational Resources and Impediments in Rural Gansu, China

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    This report seeks to provide a portrait of schools serving rural communities in northwest China, and to shed light on factors that encourage and discourage school persistence among children in this region. To achieve these goals, we analyze a survey of rural children and their families, schools, and teachers in Gansu province. The project interviewed children in the year 2000, when children were 9 to 12 years old, and again four years later. In part one of the paper, we provide a descriptive overview of the material, human, and cultural resources available in sampled primary and middle schools. Where possible, we note changes between 2000 and 2004. We describe the following types of resources: (1) basic facilities; (2) financial arrangements; (3) teachers, including their background, qualifications, working lives, professional development activities, satisfaction with work, and attitudes about school management and culture; and (4) classroom environments, as reported by teachers and by students. In this descriptive section of the paper, we highlight basic infrastructure issues, the complexity of financial arrangements at the time of the surveys, problems of teacher wage arrears and teacher morale, and the pedagogies and learning environments in classrooms, as reported by teachers and students. In part two of the paper, we investigate reasons for school leaving reported by village leaders, families, and children themselves, and analyze contributors to subsequent enrollment, change in attainment, and attainment of nine years of compulsory education. Our models of family, teacher, and school effects on outcomes show that higher socio-economic status children are more likely to show grade attainment, continued enrollment, and attainment of nine years of basic education. In contrast, the gender story is mixed: girls are less likely to be enrolled, but have not gained less grades, nor are they less likely to achieve nine years of education. This finding suggests that boys may start later or repeat more. It is possible that boys are more likely to be encouraged to repeat a grade to complete it successfully or to increase high school exam scores. One significant finding is that the introduction of school and teacher effects, by and large, does not explain away the advantages of children in better off families. School and teacher effects do not consistently matter across the three outcomes. Some interesting findings include that teacher absenteeism in 2000 is associated with less attainment between 2000 and 2004; children with better-paid home room teachers are more likely to attain nine years of school; and children in schools with minban teachers are less likely to attain nine years. However, there is not a consistent story of school characteristics that help or hinder childrenʹs persistence. Reports by village-leaders, fathers, mothers, and children themselves indicate that, along with socioeconomic status, children\u27s performance and engagement are significant factors in school continuation decisions in Gansu\u27s rural villages. Multivariate analyses indicate that childrenʹs early aspirations and performance matter for later outcomes. We close by discussing the most significant strengths and weaknesses identified among the school resources discussed in part one, and the most significant supports and hindrances to favorable educational outcomes considered in part two

    Family sources of educational gender inequality in rural china: A critical assessment

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    In this paper, we investigate the gender gap in education in rural northwest China. We first discuss parental perceptions of abilities and appropriate roles for girls and boys; parental concerns about old-age support; and parental perceptions of different labor market outcomes for girls' and boys' education. We then investigate gender disparities in investments in children, children's performance at school, and children's subsequent attainment. We analyze a survey of 9-12-year-old children and their families conducted in rural Gansu Province in the year 2000, along with follow-up information about subsequent educational attainment collected 7 years later. We complement our main analysis with two illustrative case studies of rural families drawn from 11 months of fieldwork conducted in rural Gansu between 2003 and 2005 by the second author. In 2000, most mothers expressed egalitarian views about girls' and boys' rights and abilities, in the abstract. However, the vast majority of mothers still expected to rely on sons for old-age support, and nearly one in five mothers interviewed agreed with the traditional saying, "Sending girls to school is useless since they will get married and leave home." Compared to boys, girls faced somewhat lower (though still very high) maternal educational expectations and a greater likelihood of being called on for household chores. However, there was little evidence of a gender gap in economic investments in education. Girls rivaled or outperformed boys in academic performance and engagement. Seven years later, boys had attained just about a third of a year more schooling than girls-a quite modest advantage that could not be fully explained by early parental attitudes and investments, or student performance or engagement. Fieldwork confirmed that parents of sons and daughters tended to have high aspirations for their children. Parents sometimes viewed boys as having greater aptitude, but tended to view girls as having more dedication-an attribute parents perceived as being critical for educational success. Findings suggest that at least in Gansu, rural parental educational attitudes and practices toward boys and girls are more complicated and less uniformly negative for girls than commonly portrayed. © 2009 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex

    Random Copolymers Outperform Gradient and Block Copolymers in Stabilizing Organic Photovoltaics

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    Recent advances have led to conjugated polymer‐based photovoltaic devices with efficiencies rivaling amorphous silicon. Nevertheless, these devices become less efficient over time due to changes in active layer morphology, thereby hindering their commercialization. Copolymer additives are a promising approach toward stabilizing blend morphologies; however, little is known about the impact of copolymer sequence, composition, and concentration. Herein, the impact of these parameters is determined by synthesizing random, block, and gradient copolymers with a poly(3‐hexylthiophene) (P3HT) backbone and side‐chain fullerenes (phenyl‐C61‐butyric acid methyl ester (PC61BM)). These copolymers are evaluated as compatibilizers in photovoltaic devices with P3HT:PC61BM as the active layer. The random copolymer with 20 mol% fullerene side chains and at 8 wt% concentration in the blend gives the most stable morphologies. Devices containing the random copolymer also exhibit higher and more stable power conversion efficiencies than the control device. Combined, these studies point to the random copolymer as a promising new scaffold for stabilizing bulk heterojunction photovoltaics.Photovoltaic devices made from conjugated polymers now exhibit efficiencies rivaling amorphous silicon; however, the poor longevity of these devices continues to stymie their commercial impact. Copolymer additives represent a promising solution, yet little is known about how the copolymer sequence, composition, and concentration influence their compatibilizing abilities. Herein, random copolymer additives lead to higher efficiency and longer‐lasting photovoltaic devices.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150505/1/adfm201900467.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150505/2/adfm201900467_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150505/3/adfm201900467-sup-0001-S1.pd

    A method for measuring the Neel relaxation time in a frozen ferrofluid

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    We report a novel method of determining the average Neel relaxation time and its temperature dependence by calculating derivatives of the measured time dependence of temperature for a frozen ferrofluid exposed to an alternating magnetic field. The ferrofluid, composed of dextran-coated Fe3O4 nanoparticles (diameter 13.7 nm +/- 4.7 nm), was synthesized via wet chemical precipitation and characterized by x-ray diffraction and transmission electron microscopy. An alternating magnetic field of constant amplitude (H0 = 20 kA/m) driven at frequencies of 171 kHz, 232 kHz and 343 kHz was used to determine the temperature dependent magnetic energy absorption rate in the temperature range from 160 K to 210 K. We found that the specific absorption rate of the ferrofluid decreased monotonically with temperature over this range at the given frequencies. From these measured data, we determined the temperature dependence of the Neel relaxation time and estimate a room-temperature magnetocrystalline anisotropy constant of 40 kJ/m3, in agreement with previously published results

    Up-Regulation Thioredoxin Inhibits Advanced Glycation End Products-Induced Neurodegeneration

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    Background/Aims: Diabetic retinopathy (DR) is one of the most serious complications of diabetes and is the leading cause of adult blindness in developed countries. Advanced glycation end products (AGEs) accumulation in diabetes is associated with its complications. Thioredoxin (Trx) is a small molecule (12kDa) antioxidant protein widely distributed in mammalian tissues, which has important biological functions including anti-apoptosis and transcriptional regulation. In a previous study, we found that Trx plays a key role in retinal neurodegeneration prior to the occurrence of endothelial damage in diabetic mice. In this study, our aim is to determine the effect of Trx on neurodegeneration induced by AGEs in order to identify new therapeutic targets for the clinical treatment and prevention of DR. Methods: In vivo, a high-fat diet and Streptozotocin (STZ) injection were used to generate a mouse model of diabetes. Histology was utilized to examine tissue morphology and measure the outer nuclear layer (ONL) thickness. Electroretinography (ERG) was used to assess retinal function and Western blot was used to examine protein expression. In vitro, three methods of Trx up-regulation were used, including a stable cell line that overexpresses Trx, treatment with Sulforaphane, and shRNA down-regulation Txnip. Cells were treated with AGEs, and level of apoptosis was performed to quantify this by flow cytometry and TUNEL. Quantitative Reverse Transcription PCR (qRT-PCR), Western blotting and immunofluorescence were used to measure gene and protein expression. Transmission electron microscopy (TEM) was used to observe autophagosomes. Results: We found that diabetic mice display decreased retinal function and reduced ONL thickness with AGEs accumulation and a reduction of Trx expression. Up-regulation Trx can prevent the ONL thickness decrease in diabetic mice, as observed by H&E staining. In vitro, up-regulation Trx resulted in decreased intracellular ROS generation, reduced apoptosis by inhibited autophagy. Conclusion: Up-regulating Trx inhibited neurodegeneration induced by AGEs. The underlying mechanism may be related to inhibit Txnip/mTOR pathway-mediated autophagy

    Single-cell analysis reveals regional reprogramming during adaptation to massive small bowel resection in mice

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    BACKGROUND & AIMS: The small intestine (SI) displays regionality in nutrient and immunological function. Following SI tissue loss (as occurs in short gut syndrome, or SGS), remaining SI must compensate, or adapt ; the capacity of SI epithelium to reprogram its regional identity has not been described. Here, we apply single-cell resolution analyses to characterize molecular changes underpinning adaptation to SGS. METHODS: Single-cell RNA sequencing was performed on epithelial cells isolated from distal SI of mice following 50% proximal small bowel resection (SBR) vs sham surgery. Single-cell profiles were clustered based on transcriptional similarity, reconstructing differentiation events from intestinal stem cells (ISCs) through to mature enterocytes. An unsupervised computational approach to score cell identity was used to quantify changes in regional (proximal vs distal) SI identity, validated using immunofluorescence, immunohistochemistry, qPCR, western blotting, and RNA-FISH. RESULTS: Uniform Manifold Approximation and Projection-based clustering and visualization revealed differentiation trajectories from ISCs to mature enterocytes in sham and SBR. Cell identity scoring demonstrated segregation of enterocytes by regional SI identity: SBR enterocytes assumed more mature proximal identities. This was associated with significant upregulation of lipid metabolism and oxidative stress gene expression, which was validated via orthogonal analyses. Observed upstream transcriptional changes suggest retinoid metabolism and proximal transcription factor Creb3l3 drive proximalization of cell identity in response to SBR. CONCLUSIONS: Adaptation to proximal SBR involves regional reprogramming of ileal enterocytes toward a proximal identity. Interventions bolstering the endogenous reprogramming capacity of SI enterocytes-conceivably by engaging the retinoid metabolism pathway-merit further investigation, as they may increase enteral feeding tolerance, and obviate intestinal failure, in SGS

    Development of a CsI Calorimeter for the Compton-Pair (ComPair) Balloon-Borne Gamma-Ray Telescope

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    There is a growing interest in astrophysics to fill in the observational gamma-ray MeV gap. We, therefore, developed a CsI:Tl calorimeter prototype as a subsystem to a balloon-based Compton and Pair-production telescope known as ComPair. ComPair is a technology demonstrator for a gamma-ray telescope in the MeV range that is comprised of 4 subsystems: the double-sided silicon detector, virtual Frisch grid CdZnTe, CsI calorimeter, and a plastic-based anti-coincidence detector. The prototype CsI calorimeter is composed of thirty CsI logs, each with a geometry of 1.67×1.67×10 cm31.67 \times 1.67 \times 10 \ \mathrm{cm^3}. The logs are arranged in a hodoscopic fashion with 6 in a row that alternate directions in each layer. Each log has a resolution of around 8%8 \% full-width-at-half-maximum (FWHM) at 662 keV662 \ \mathrm{keV} with a dynamic energy range of around 250 keV30 MeV250\ \mathrm{keV}-30 \ \mathrm{MeV}. A 2×22\times2 array of SensL J-series SiPMs read out each end of the log to estimate the depth of interaction and energy deposition with signals read out with an IDEAS ROSSPAD. We also utilize an Arduino to synchronize with the other ComPair subsystems that comprise the full telescope. This work presents the development and performance of the calorimeter, its testing in thermal and vacuum conditions, and results from irradiation by 225 MeV2-25 \ \mathrm{MeV} monoenergetic gamma-ray beams. The CsI calorimeter will fly onboard ComPair as a balloon experiment in the summer of 2023

    TCAF1 promotes TRPV2-mediated Ca2+ release in response to cytosolic DNA to protect stressed replication forks

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    The protection of the replication fork structure under stress conditions is essential for genome maintenance and cancer prevention. A key signaling pathway for fork protection involves TRPV2-mediated C
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