The outbreak of the COVID-19 pandemic has led to widespread school shutdowns, and many schools have opted for education using online learning platforms. Using administrative data from three middle schools in China, this paper estimates the causal effects of online learning on student performance. Using the difference-in-differences approach, we show that online education improves students' academic achievement by 0.22 of a standard deviation, relative to those who stopped receiving learning support from their school during the COVID-19 lockdown. All else equal, students from a school having access to recorded online lessons delivered by external higher-quality teachers have achieved more progress in academic outcomes than those accessing lessons recorded by teachers in their own school. We find no evidence that the educational benefits of distance learning differ for rural and urban students. However, there is more progress in the academic achievement of students using a computer for online education than that of those using a smartphone.Last, low achievers benefit the most from online learning while there is no significant impact for top students. Our findings have important policy implications for educational practices when lockdown measures are implemented during a pandemic.

Activation of protein kinase C (PKC) increases vesicular secretion in many cell types. We determined the calcium dependence of secretion and the size of the readily releasable pool of secretory granules in pituitary gonadotropes by photorelease of caged-calcium. The calcium affinity for exocytosis was roughly doubled by activation of PKC by a phorbol ester, whereas the size of the readily releasable pool was not greatly increased. The effect was due to activation of PKC, because it was blocked by a PKC inhibitor and was not mimicked by an inactive phorbol ester analogue. A similar increase in calcium sensitivity was induced by preincubation with gonadotropin-releasing hormone, the physiological releasing hormone. These findings provide direct evidence for physiological regulation of secretion by enhancement of Ca2+-sensing steps. Because exocytosis depends on the third- to fourth-power of intracellular free Ca2+ concentration, this mechanism ensures a powerful up-regulation of hormone release and may explain how PKC can stimulate exocytosis without an increase of Ca2+ above the resting level.

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Novel micrometer-sized indium oxyhydroxide (InOOH) hollow spheres were successfully synthesized via a citric acid (CA) assisted hydrothermal process. The morphology, crystal structure, and optical properties of the product were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and UV-vis diffuse reflectance spectroscopy (DRS). The optical band gap, E(g), was estimated to be 3.5 eV from the DRS spectrum, which is almost equal to that of indium oxide. Furthermore, on the basis of a series of SEM observations, phenomenological elucidation of a mechanism for the growth of the InOOH hollow spheres has been presented; key factors for the formation of the structures have been proposed.

Background Postoperative delirium (POD) is common and has negative effects on elderly patients. There is a critical need to identify patients at high risk of POD so that providers can better offer targeted interventions in the preoperative and intraoperative periods. We aimed to characterize the prevalence of preoperative anxiety and investigate whether preoperative anxiety predicted the onset of POD in elderly patients undergoing elective orthopedic surgery. Methods We conducted a prospective observational cohort study of elderly patients (aged 65 years or older) undergoing elective orthopedic surgery. Preoperative anxiety was assessed using the Hospital Anxiety and Depression Scale-Anxiety (HADS-A), with clinically significant values defined as HADS-A>7. POD was diagnosed according to the Confusion Assessment Method (CAM) criteria on the 5 postoperative days. To determine the independent risk factors for POD, multivariable logistic regression was conducted, including those variables with a p-value <0.05 at univariate analysis. Results There were 263 patients included in the study. Seventy-three (27.8%) patients were diagnosed to be POD. Median duration of delirium was 2 days. Forty (15.2%) patients were assessed to experience preoperative anxiety. The occurrence of preoperative anxiety in total hip arthroplasty (THA), proximal femoral nail antirotation (PFNA), and total knee arthroplasty (TKA) was 12.5%, 16.1%, and 19.5%, respectively. Based on multivariable analysis, only age (odds ratio [OR]= 1.099, 95% Confidence Interval [CI]: 1.013–1.192; P =0.023), Mini Mental State Examination (MMSE) (OR= 0.603, 95% CI: 0.432–0.842; P =0.003) and preoperative anxiety (OR= 3.119, 95% CI: 1.144–8.500; P =0.026) were independently associated with POD. Conclusion In conclusion, the current study reveals that preoperative anxiety helps to predict the risk of POD in elderly patients undergoing elective orthopedic surgery. Relieving preoperative anxiety could be a new target for preventive interventions to reduce POD.

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