The Impact of the COVID-19 Pandemic on User Experience with Online Education Platforms in China

During the COVID-19 pandemic, social education has shifted from face to face to online in order to avoid large gatherings and crowds for blocking the transmission of the virus. To analyze the impact of virus on user experience and deeply retrieve users’ requirements, this paper constructs a reasonable evaluation index system through obtaining user reviews about seven major online education platforms before and after the outbreak of COVID-19, and by combining the emotional analysis, hot mining technology, as well as relevant literature. At the same time, the variation coefficient method is chosen to weigh each index based on the difference of index values. Furthermore, this paper adopts the comprehensive evaluation method to analyze user experience before and after the outbreak of COVID-19, and finally finds out the change of users’ concerns regarding the online education platform. In terms of access speed, reliability, timely transmission technology of video information, course management, communication and interaction, and learning and technical support, this paper explores the supporting abilities and response levels of online education platforms during COVID-19, and puts forward corresponding measures to improve how these platforms function

Correction: Embryonic Stem Cells Markers SOX2, OCT4 and Nanog Expression and Their Correlations with Epithelial-Mesenchymal Transition in Nasopharyngeal Carcinoma

Expression of embryonic stem cells (ESCs) markers (SOX2, OCT4, Nanog and Nestin) is crucial for progression of various human malignancies. The purpose of this study was to investigate the expression and prognostic impact of these molecules in nasopharyngeal carcinoma (NPC) patients by immunohistochemistry and immunofluorescence. In the present study, we found that the expression levels of SOX2, OCT4 and Nanog were highly expressed in NPC compared with the non-tumorous tissues. Furthermore, these proteins correlated significantly with several clinicalpathological factors and epithelial-mesenchymal transition (EMT)-associated indicators (E-cadherin/N-cadherin and Snail). In multivariate analyses, high expression of OCT4 (P = 0.013) and Nanog (P = 0.040), but not that of SOX2, was associated with worse survival and had strongly independent prognostic effects. Of note, OCT4 and Nanog were more frequently located at the invasive front of tumors, and correlated significantly with various aggressive behaviors including T classification, N classification, M classification and clinical stage. Furthermore, patients with co-expression of OCT4 and Nanog in the invasive front had significantly worse survival (P = 0.005). Interestingly, at the invasive front, these molecules correlated significantly with Nestin expression in endothelial cells (P<0.001). These findings provide evidence that ESCs biomarkers OCT4 and Nanog serves as independent prognostic factors for NPC. Additionally, cancer cells in the invasive front of NPC acquiring ESCs-like features should be maintained by vascular niches

A New Approach for Determining the Control Volumes of Production Wells considering Irregular Well Distribution and Heterogeneous Reservoir Properties

The oil and gas fields are commonly developed with a group of production wells. Therefore, it can be essential for the industries to predict the performance of the production wells in order to optimize the development strategies. In practice, it frequently happens that we only hope to study the performance of a single production well. In such cases, it can be time consuming to run the reservoir simulation with the entire reservoir model to study the well performance. Hence, it can be preferred to determine the control volume (or drainage volume) of the target well from the entire reservoir and run the simulation with the small control volume to reduce the simulation cost. However, an irregular layout of the production wells and the heterogeneity of reservoir properties, which can be commonly observed in real field cases, can induce a stringent barrier for one to determine the control volumes. At present, we are still lacking a method to determine the control volumes of the production wells considering well distribution and reservoir heterogeneities. In order to overcome such a barrier, the authors proposed a new approach to divide the entire reservoir into small control volumes on the basis of the fast marching method (FMM). This approach is validated by comparing the simulation outputs of the target well calculated only with the determined control volume to those calculated with the entire reservoir model. The calculated results show that using the control volume that is determined with the proposed method to calculate the well performance can yield results that agree well with the results that are calculated with the entire reservoir model. This indicates that this proposed method is reliable to determine the control volume of the production wells. In addition, the calculated results in this work show that changing fracture length exerts a slight influence on the control volumes if the length of all fractures is increased, whereas, if only one of the fracture lengths is increased, the control volume of the corresponding well will be significantly increased. The number of the production wells and the distribution of the production well can noticeably influence the control volumes of the production wells. The findings of this study can help for optimizing the well spacing, estimating the ultimate recovery, and reducing the computational cost

Immunohistochemical staining of embryonic stem cells (ESCs) proteins SOX2, OCT4, Nanog and Nestin in non-cancerous nasopharyngeal tissues and nasopharyngeal carcinoma (NPC).

<p>Nuclear SOX2 expression was low in non-tumoral epithelium (A), whereas it was highly expressed in NPC tissues (B). Nuclear staining of OCT4 was limited to basal cells of non-tumoral epithelium (D; arrows indicated) and markedly expressed in tumor cells (E). Low cytoplasmic expression of Nanog was observed in non-tumoral epithelium (G) and strongly displayed in tumor tissues (H). Nestin expression was completely absent in non-cancerous epithelium (J) and tumor cells (K), whereas it was strongly stained in the cytoplasm of endothelial cells in cancer tissues (K; arrows indicated). Immunofluorescent labeling of both SOX2 (C) and OCT4 (C) showed nuclear staining (red), Nanog (I) and Nestin (L) showed cytoplasmic localization (red) of tumor cells and endothelial cells, respectively, DAPI (blue).All images, ×400.</p

Influence of SOX2, OCT4 and Nanog expression on overall survival of NPC patients.

<p>There was no significant difference in the overall survival between low and high nuclear SOX2 expression(A). Patients showed worse overall survival with high nuclear OCT4 (B), cytoplasmic Nanog (C) and coexpression of OCT4 and Nanog (D) in tumors. Patients with high expression of nuclear SOX2 (E), nuclear OCT4 (F), cytoplasmic Nanog (G) and coexpression of OCT4 and Nanog (H) in the invasive front of tumors showed worse overall survival. <i>P</i>-values were calculated by log-rank test.</p

Immunohistochemical expression levels of SOX2, OCT4, Nanog and Nestin in the invasive front of NPC (arrows indicated).

<p>Strong staining of nuclear SOX2 (A, B) was mostly found at the tumor invasive front. High staining of nuclear OCT4 (C, D) was observed in the invasive front of tumors. Cytoplasmic Nanog expression (E, F) was particularly evident at the invasive edge of tumors. <b>Of note</b>, these cells often exhibited a fibroblast-like, spindle-shaped phenotype. On the other hand, Nestin expression in blood vessels (G, H) were distributed predominantly at the invasive front of tumors. (A, C, E, G×100; B, D, F, H×400, respectively).</p

NF-kappaB and AP-1 connection: mechanism of NF-kappaB-dependent regulation of AP-1 activity.

Nuclear factor kappaB (NF-kappaB) and activator protein 1 (AP-1) transcription factors regulate many important biological and pathological processes. Activation of NF-kappaB is regulated by the inducible phosphorylation of NF-kappaB inhibitor IkappaB by IkappaB kinase. In contrast, Fos, a key component of AP-1, is primarily transcriptionally regulated by serum responsive factors (SRFs) and ternary complex factors (TCFs). Despite these different regulatory mechanisms, there is an intriguing possibility that NF-kappaB and AP-1 may modulate each other, thus expanding the scope of these two rapidly inducible transcription factors. To determine whether NF-kappaB activity is involved in the regulation of fos expression in response to various stimuli, we analyzed activity of AP-1 and expression of fos, fosB, fra-1, fra-2, jun, junB, and junD, as well as AP-1 downstream target gene VEGF, using MDAPanc-28 and MDAPanc-28/IkappaBalphaM pancreatic tumor cells and wild-type, IKK1-/-, and IKK2-/- murine embryonic fibroblast cells. Our results show that elk-1, a member of TCFs, is one of the NF-kappaB downstream target genes. Inhibition of NF-kappaB activity greatly decreased expression of elk-1. Consequently, the reduced level of activated Elk-1 protein by extracellular signal-regulated kinase impeded constitutive, serum-, and superoxide-inducible c-fos expression. Thus, our study revealed a distinct and essential role of NF-kappaB in participating in the regulation of elk-1, c-fos, and VEGF expression

NF-κB and AP-1 Connection: Mechanism of NF-κB-Dependent Regulation of AP-1 Activity

Nuclear factor κB (NF-κB) and activator protein 1 (AP-1) transcription factors regulate many important biological and pathological processes. Activation of NF-κB is regulated by the inducible phosphorylation of NF-κB inhibitor IκB by IκB kinase. In contrast, Fos, a key component of AP-1, is primarily transcriptionally regulated by serum responsive factors (SRFs) and ternary complex factors (TCFs). Despite these different regulatory mechanisms, there is an intriguing possibility that NF-κB and AP-1 may modulate each other, thus expanding the scope of these two rapidly inducible transcription factors. To determine whether NF-κB activity is involved in the regulation of fos expression in response to various stimuli, we analyzed activity of AP-1 and expression of fos, fosB, fra-1, fra-2, jun, junB, and junD, as well as AP-1 downstream target gene VEGF, using MDAPanc-28 and MDAPanc-28/IκBαM pancreatic tumor cells and wild-type, IKK1(−/−), and IKK2(−/−) murine embryonic fibroblast cells. Our results show that elk-1, a member of TCFs, is one of the NF-κB downstream target genes. Inhibition of NF-κB activity greatly decreased expression of elk-1. Consequently, the reduced level of activated Elk-1 protein by extracellular signal-regulated kinase impeded constitutive, serum-, and superoxide-inducible c-fos expression. Thus, our study revealed a distinct and essential role of NF-κB in participating in the regulation of elk-1, c-fos, and VEGF expression