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In this study, the distribution characteristics of scale height at various solar activity levels were statistically analyzed using the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) radio occultation data for 2007–2013. The results show that: (1) in the mid-high latitude region, the daytime (06–17LT) scale height exhibits annual variations in the form of a single peak structure with the crest appearing in summer. At the high latitude region, an annual variation is also observed for nighttime (18–05LT) scale height; (2) changes in the spatial distribution of the scale height occur. The crests are deflected towards the north during daytime (12–14LT) at a geomagnetic longitude of 60°W–180°W, and they are distributed roughly along the geomagnetic equator at 60°W–180°E. In the approximate region of 120°W–150°E and 50°S–80°S, the scale height values are significantly higher than those in other mid-latitude areas. This region enlarges with increased solar activity, and shows an approximately symmetric distribution about 0° geomagnetic longitude. Nighttime (00–02LT) scale height values in the high-latitude region are larger than those in the low–mid latitude region. These results could serve as reference for the study of ionosphere distribution and construction of the corresponding profile model.

Galileo mission detected the magnetic anomalies originated from Galilean moons. These anomalies are likely generated in the moons＇ interiors, under the influence of a strong ambient Jovian field. Among various possible generation mechanisms of the anomalies, we focus on magneto-convection and dynamos in the interiors via numerical simulation. To mimic the electromagnetic environment of the moons, we introduce in our numerical model an external uniform magnetic field B0 with a fixed orientation but varying field strength. Our results show that a finite B0 can substantially alter the dynamo processes inside the core When the ambient field strength B0 increases to approximately 40% of the field generated by the pure dynamo action, the convective state in the core changes significantly： the convective flow decreases by 80% in magnitude, but the differential rotation becomes stronger in much of the fluid layer, leading to a stronger field generated in the core. The field morphologies inside the core tend to align with the ambient field, while the flow patterns show the symmetry-breaking effect under the influence of B0. Furthermore, the generated field tends to be temporally more stable.

利用卫星高度计资料,研究了季节内Kelvin波在印度尼西亚贯穿流海域的传播。起源于赤道印度洋的Kelvin波抵达印度洋东边界后,以沿岸Kelvin波的形式沿苏门答腊-爪哇岛西南沿岸向东传播,15天后抵达龙目海峡,并分为三支：一支向北传播,5天后抵达望加锡海峡,相速度约为1.69 m s^-1;一支向东传播,5天后抵达翁拜海峡,相速度约为1.91–2.86 m s^-1;一支沿松巴岛西南沿岸传播,相速度约为1.96 m s^-1。季节内Kelvin波在该海域的传播速度与第一和第二斜压模Kelvin波一致。

Peptide-mediated cell-to-cell signaling has crucial roles in coordination and definition of cellular functions in plants. Peptide-receptor matching is important for understanding the mechanisms underlying peptide-mediated sig- naling. Here we report the structure-guided identification of root meristem growth factor （RGF） receptors important for plant development. An assay based on a signature ligand recognition motif （Arg-x-Arg） conserved in a subfamily of leucine-rich repeat receptor kinases CLRR-RKs） identified the functionally uncharacterized LRR-RK At4926540 as a receptor of RGF1 （RGFR1）. We further solved the crystal structure of RGF1 in complex with the LRR domain of RGFR1 at a resolution of 2.6 A, which reveals that the Arg-x-Gly-Gly （RxGG） motif is responsible for specific rec- ognition of the sulfate group of RGF1 by RGFR1. Based on the RxGG motif, we identified additional four RGFRs. Participation of the five RGFRs in RGF-induced signaling is supported by biochemical and genetic data. We also of- fer evidence showing that SERKs function as co-receptors for RGFs. Taken together, our study identifies RGF receptors and co-receptors that can link RGF signals with their downstream components and provides a proof of principle for structure-based matching of LRR-RKs with their peptide ligands.

Using novel ideas for the fabrication of epitaxial graphene （EG） on SiC, two forms of graphene termed as vertical aligned gra- phene sheets （VAGS） and graphene covered SiC powder （GCSP） were derived, respectively, from SiC slices and SiC powder, aimed for applications in energy storage and photocatalysis. Herein, the fabrication procedures, morphology characteristics, some intrinsic physical properties and performances for applications in field effect transistor （FET） and cold cathode field emission source are revealed and analyzed based on the graphene materials. The EG on a 2-inch SiC （0001） showed an average sheet resistance about 720 D,/~5 with a non-uniformity 7.2%. The FETs fabricated on the EG possessed a cutoff frequency 80 GHz. Based on the VAGS derived from a completely carbonized SiC slice, a magnetic phase diagram of graphene with irregu- lar zigzag edges is also reported.

Although new developments of surgery, chemotherapy, radiotherapy, and immunotherapy treatments for cancer have improved patient survival, the emergence of chemoresistance in cancer has significant impacts on treatment effects. The development of chemoresistance involves several polygenic, progressive mechanisms at the molecular and cellular levels, as well as both genetic and epigenetic heterogeneities. Chemotherapeutics induce epigenetic reprogramming in cancer cells, converting a transient transcriptional state into a stably resistant one. Super-enhancers (SEs) are central to the maintenance of identity of cancer cells and promote SE-driven-oncogenic transcriptions to which cancer cells become highly addicted. This dependence on SE-driven transcription to maintain chemoresistance offers an Achilles’ heel for chemoresistance. Indeed, the inhibition of SE components dampens oncogenic transcription and inhibits tumor growth to ultimately achieve combined sensitization and reverse the effects of drug resistance. No reviews have been published on SE-related mechanisms in the cancer chemoresistance. In this review, we investigated the structure, function, and regulation of chemoresistance-related SEs and their contributions to the chemotherapy via regulation of the formation of cancer stem cells, cellular plasticity, the microenvironment, genes associated with chemoresistance, noncoding RNAs, and tumor immunity. The discovery of these mechanisms may aid in the development of new drugs to improve the sensitivity and specificity of cancer cells to chemotherapy drugs.

Correspondence to Dr Guo Yu, Clinical Medical College, Yangzhou University, Yangzhou 225009, China; guoyu@yzu.edu.cn The article by Lee et al 1 showed that the current use of proton pump inhibitors (PPIs) increased the risk of severe clinical outcomes of COVID-19 rather than the susceptibility to SARS-CoV-2 infection in a Korean nationwide cohort. Analysis of five studies1–5 encompassing 145 428 patients who were tested for SARS-CoV-2 showed that the risk of SARS-CoV-2 infection was higher, although not significantly, among current PPI users (OR 1.33, 95% CI 0.86 to 2.07, p=0.20; figure 1) compared with PPI non-users, with evidence of substantial between-study heterogeneity (I 2=97%). [...]in a subgroup analysis of non-Korean cohorts,2–4 we found a significant association between current use of PPIs and increased risk of SARS-CoV-2 infection (OR 1.94, 95% CI 1.59 to 2.36, p<0.0001; online supplemental figure 2). [...]past use of PPIs was not associated with increased susceptibility to SARS-CoV-2 infection (n=1 72 833 from four studies;1 3 5 6 OR 0.85, 95% CI 0.57 to 1.27, p=0.43; I 2=92%; figure 1) or with severe outcomes of COVID-19 (n=40 097 from three studies;1 3 9 OR 1.03, 95% CI 0.85 to 1.23, p=0.79; I 2=0%; figure 2).

Di-(2-ethylhexyl) phthalate (DEHP) has the potential to disrupt the thyroid endocrine system, but the underlying mechanism is unknown. In this study, zebrafish (Danio rerio) embryos were exposed to different concentrations of DEHP (0, 40, 100, 200, 400 μg/L) from 2 to 168 hours post fertilization (hpf). Thyroid hormones (THs) levels and transcriptional profiling of key genes related to hypothalamus-pituitary-thyroid (HPT) axis were examined. The result of whole-body thyroxine (T4) and triiodothyronine (T3) indicated that the thyroid hormone homeostasis was disrupted by DEHP in the zebrafish larvae. After exposure to DEHP, the mRNA expressions of thyroid stimulating hormone (tshβ) and corticotrophin releasing hormone (crh) genes were increased in a concentration dependent manner, respectively. The expression level of genes involved in thyroid development (nkx2.1 and pax8) and thyroid synthesis (sodium/iodide symporter, nis, thyroglobulin, tg) were also measured. The transcripts of nkx2.1 and tg were significantly increased after DEHP exposure, while those of nis and pax8 had no significant change. Down-regulation of uridinediphosphate-glucuronosyl-transferase (ugt1ab) and up-regulation of thyronine deiodinase (dio2) might change the THs levels. In addition, the transcript of transthyretin (ttr) was up-regulated, while the mRNA levels of thyroid hormone receptors (trα and trβ) remained unchanged. All the results demonstrated that exposure to DEHP altered the whole-body thyroid hormones in the zebrafish larvae and changed the expression profiling of key genes related to HPT axis, proving that DEHP induced the thyroid endocrine toxicity and potentially affected the synthesis, regulation and action of thyroid hormones.

One great challenge in understanding the history of life is resolving the influence of environmental change on biodiversity. Simulated annealing and genetic algorithms were used to synthesize data from 11,000 marine fossil species, collected from more than 3000 stratigraphic sections, to generate a new Cambrian to Triassic biodiversity curve with an imputed temporal resolution of 26 ± 14.9 thousand years. This increased resolution clarifies the timing of known diversification and extinction events. Comparative analysis suggests that partial pressure of carbon dioxide (PCO2) is the only environmental factor that seems to display a secular pattern similar to that of biodiversity, but this similarity was not confirmed when autocorrelation within that time series was analyzed by detrending. These results demonstrate that fossil data can provide the temporal and taxonomic resolutions necessary to test (paleo)biological hypotheses at a level of detail approaching those of long-term ecological analyses.

Background Clinical internships are a critical transition period for nursing students to develop into nursing professionals and are essential for the solidification of their professional attitudes. Undergraduate nursing students face multiple sources of severe anxiety that affect their nursing career development during this period. This study aimed to understand the anxiety experienced by undergraduate nursing students in the later period of their internship periods in a Chinese educational context. Methods A descriptive qualitative study was conducted. A purposive sample of 17 undergraduate nursing interns with experiences of anxiety was selected from three teaching hospitals in Hunan Province, China . Data were collected through semi-structured interviews and analyzed using the Colaizzi seven-step method for data analysis. Results Three themes emerged: the sources of perceived anxiety, the psychological journey of coping with anxiety, and suggestions for nursing management and education. The sub-themes for the first theme included career decision dilemmas, competitive pressures for employment, worries about progress of the graduation projects, challenges of the nursing licensure examination, and low self-confidence in clinical competence. The second theme consisted of two sub-themes: negative avoidance and retreat, and positive preparation and response. The third theme consisted of policy support to create more employment opportunities, comprehensive guidance from nursing schools and hospitals, and psychological assistance and counseling. Conclusions This study revealed that undergraduate nursing students were prone to anxiety during the later period of their clinical internships. Specific sources of anxiety encompassed career decision-making, job pursuit, graduation, and licensure examination. Undergraduate nursing students adopted both positive and negative approaches in coping with anxiety during the later period of their clinical internships. Nursing educators and administrators should develop appropriate instructions and support systems to reduce anxiety among undergraduate nursing students.