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83 result(s) for "Sun, Xiao-Ya"
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KIC 9845907: A δ Scuti Star with the First Overtone as the Dominant Frequency and with Many Equidistant Structures in Its Spectrum
In this paper, we present an analysis of the pulsating behavior of Kepler target KIC 9845907. Using the data from Kepler, we detected 85 significant frequencies, including the first overtone f 1 = 17.597 day−1 as the dominant frequency, the non-radial independent frequency f 3 = 31.428 day−1 (ℓ = 1), as well as two modulation terms f m1 = 0.065 day−1 and f m2 = 1.693 day−1. We found fourteen pairs of triplet structures with f m1 or f m2, four pairs of which can further form quintuplet structures. We note these are the most intriguing features discovered in this study and they were recognized for the first time in δ Scuti stars. We discussed several possible explanations, i.e., beating, the Blazhko effect, combination mode hypothesis, nonlinear mode coupling, large separation, and stellar rotational splitting for these equidistant structures. Our asteroseismic models indicate this modulation with f m1 might be related to the rotational splitting. The study of more δ Scuti stars with triplet and/or quintuplet structures using high-precision space photometry would be helpful to further explore its origin.
Asteroseismology of Triple-mode Radial δ Scuti Star: TIC 400562821
We investigated the pulsating behavior of TIC 400562821 using high-precision observations from TESS. Fourier analysis of time-series data revealed three independent frequencies. The period ratios of F to F1 (0.774) and F to F2 (0.625), along with an amplitude change of approximately 0.1 mag, indicate that TIC 400562821 is a triple-mode High-Amplitude δ Scuti (HADS) star. Using the Best Parent Method and the Γ O functions, we identified that the harmonics and sum combination frequencies of F and F1 are caused by the nonlinear response of the stellar medium to pulsation. We also analyzed the amplitude variations of F, F1, and F2. Observational data over 76 days show stable amplitudes for these modes. However, Radial Stellar Pulsations modeling suggests that, over 10,000 cycles, the amplitude of F remains constant, while F1 gradually decreases and F2 approaches zero. This implies that TIC 400562821 may eventually evolve into a single-mode HADS star. Furthermore, asteroseismic modeling was performed, and several effects, such as the mixing-length parameter α MLT and nonadiabatic, were examined on this star. In view of the results by Daszyńska-Daszkiewicz et al. (i.e., α MLT < ∼1 for δ Scuti stars), TIC 400562821 is suggested to be more likely in the post-main-sequence stage, with mass M = 1.34–1.38 M ⊙ and metallicity Z = 0.007–0.008, but still warrants further study to ascertain its nature.
LPAR5 confers radioresistance to cancer cells associated with EMT activation via the ERK/Snail pathway
Background Epithelial-to-mesenchymal transition (EMT) is a critical event contributing to more aggressive phenotypes in cancer cells. EMT is frequently activated in radiation-targeted cells during the course of radiotherapy, which often endows cancers with acquired radioresistance. However, the upstream molecules driving the signaling pathways of radiation-induced EMT have not been fully delineated. Methods In this study, RNA-seq-based transcriptome analysis was performed to identify the early responsive genes of HeLa cells to γ-ray irradiation. EMT-associated genes were knocked down by siRNA technology or overexpressed in HeLa cells and A549 cells, and the resulting changes in phenotypes of EMT and radiosensitivity were assessed using qPCR and Western blotting analyses, migration assays, colony-forming ability and apoptosis of flow cytometer assays. Results Through RNA-seq-based transcriptome analysis, we found that LPAR5 is downregulated in the early response of HeLa cells to γ-ray irradiation. Radiation-induced alterations in LPAR5 expression were further revealed to be a bidirectional dynamic process in HeLa and A549 cells, i.e., the early downregulating phase at 2 ~ 4 h and the late upregulating phase at 24 h post-irradiation. Overexpression of LPAR5 prompts EMT programing and migration of cancer cells. Moreover, increased expression of LPAR5 is significantly associated with IR-induced EMT and confers radioresistance to cancer cells. Knockdown of LPAR5 suppressed IR-induced EMT by attenuating the activation of ERK signaling and downstream Snail, MMP1, and MMP9 expression. Conclusions LPAR5 is an important upstream regulator of IR-induced EMT that modulates the ERK/Snail pathway. This study provides further insights into understanding the mechanism of radiation-induced EMT and identifies promising targets for improving the effectiveness of cancer radiation therapy.
Natural source, bioactivity and synthesis of 3-Arylcoumarin derivatives
3-arylcoumarins with different pharmacological properties widely exist in a variety of natural plants. The extensive research on 3-arylcoumarins was attributed to its therapeutic and relatively easy isolation. Therefore, 3-arylcoumarins can be recognised as useful structures for the design of novel compounds with potential pharmacological interest, particularly in the fields of anti-inflammatory, anti-cancer, antioxidant, Monoamine oxidase (MAO) enzyme inhibition, etc. The current review highlights the biological activities, design, and chemical synthetic methods of 3-arylcoumarins derivatives as well as their important natural product sources.
KIC 2857323: A Double-mode High-amplitude δ Scuti Star with Amplitude Decline of the First Overtone Mode
We investigate the pulsating behavior of KIC 2857323 using high-precision observations from the Kepler mission. Fourier analysis of 4 yr time-series data reveals five independent frequencies for the light variation. Among them, two strong frequencies f 1 and f 3 with a period ratio of 0.774 identify this star as a double-mode (i.e., the fundamental mode F0 and first overtone mode F1) high-amplitude δ Scuti star (HADS). Seismic modeling using the two radial modes F0 and F1 indicates that KIC 2857323 is a main-sequence star with mass M = 1.78 ± 0.02 M ⊙ and metallicity Z from 0.009 to 0.012. We analyze the phase and amplitude variations of F0 and F1 using the phase modulation method and find that the first overtone mode F1 shows a slow decline in amplitude. We discuss several possible causes for the amplitude variation and speculate that the amplitude decline in this star may be due to pulsation energy loss. We note that KIC 2857323 is the first double-mode HADS to show amplitude decline and warrants further study to ascertain its nature.
Identifying Differential Gene Expression in Wing Polymorphism of Adult Males of the Largest Water Strider: De novo Transcriptome Assembly for Gigantometra gigas (Hemiptera: Gerridae)
Wing polymorphism is common in a wide variety of insect species. However, few studies have reported on adaptations in the wing polymorphism of insects at molecular level, in particular for males. Thus, the adaptive mechanisms need to be explored. The remarkable variability in wing morphs of insects is well represented in the water striders (Hemiptera: Gerridae). Within this family, Gigantometra gigas (China, 1925), the largest water strider known worldwide, displays macropterous and apterous males. In the present study, we used de novo transcriptome assembly to obtain gene expression information and compared body and leg-component lengths of adult males in different wing morphs. The analyses in both gene expression and phenotype levels were used for exploring the adaptive mechanism in wing polymorphism of G. gigas. After checking, a series of highly expressed structural genes were found in macropterous morphs, which were related to the maintenance of flight muscles and the enhancement of flight capacity, whereas in the apterous morphs, the imaginal morphogenesis protein-Late 2 (Imp-L2), which might inhibit wing development and increase the body size of insects, was still highly expressed in the adult stage. Moreover, body and leg-component lengths were significantly larger in apterous than in macropterous morphs. The larger size of the apterous morphs and the differences in highly expressed genes between the two wing morphs consistently demonstrate the adaptive significance of wing polymorphism in G. gigas. These results shed light on the future loss-of-function research of wing polymorphism in G. gigas.
FTO-dependent demethylation of N6-methyladenosine regulates mRNA splicing and is required for adipogenesis
The role of Fat Mass and Obesity-associated protein (FTO) and its substrate N6-methyladenosine (m6A) in mRNA processing and adipogenesis remains largely unknown. We show that FTO expression and m6A levels are inversely correlated during adipogenesis. FTO depletion blocks differentiation and only catalytically active FTO restores adi- pogenesis. Transcriptome analyses in combination with m6A-seq revealed that gene expression and mRNA splicing of grouped genes are regulated by FTO. M6A is enriched in exonic regions flanking 5'- and 3'-splice sites, spatially over- lapping with mRNA splicing regulatory serine/arginine-rich (SR) protein exonic splicing enhancer binding regions. Enhanced levels of m6A in response to FTO depletion promotes the RNA binding ability of SRSF2 protein, leading to increased inclusion of target exons. FTO controls exonic splicing of adipogenie regulatory factor RUNX1T1 by regulating m6A levels around splice sites and thereby modulates differentiation. These findings provide compelling evidence that FTO-dependent m6A demethylation functions as a novel regulatory mechanism of RNA processing and plays a critical role in the regulation of adipogenesis.
Diagnostic Significance of Intraoperative Ultrasound Contrast in Evaluating the Resection Degree of Brain Glioma By Transmission Electron Microscopic Examination
Background:Contrast-enhanced ultrasound is a dynamic and continuous modality providing real-time view of vascularization and flow distribution patterns of different organs and tumors.In order to evaluate the diagnostic significance of intraoperative contrast-enhanced ultrasound in assessing the resection degree of brain glioma by transmission electron microscopic (TEM) examination,it is important to have specific knowledge about contrast-enhanced ultrasound.Methods:Ultrasound contrast was applied in operations of 120 cases of brain glioma,to evaluate the degree of tumor resection.Biopsy tissues were obtained the suspicious residual tumors surrounding the tumor cavity.The sensitivity and specificity of the residual tumors were determined by the intraoperative ultrasound contrast according to TEM examination results.Results:There were 44 cases of low-grade gliomas and 76 cases of high-grade gliomas.Three hundred and sixty biopsy tissues were obtained.The sensitivity of intraoperative ultrasound contrast in diagnosing the residual tumor was 62.2%,while the specificity degree of it was 92.8%.The consistency coefficient of the ultrasound contrast diagnosis and TEM examination results was 0.584 (Kappa =0.584),which was between 0.4 and 0.6,therefore it was of medium consistency.Conclusions:Intraoperative ultrasound contrast was of a high sensitivity and specificity in evaluating the excision degree of tumor.The consistency of the residual tumor rate detected,respectively,by ultrasound contrast and TEM examination was of medium consistency.The application of intraoperative ultrasound contrast can improve the resection rate of brain glioma.
KIC 9845907: A \\(\\) Scuti star with the first overtone as the dominant frequency and with many equidistant structures in its spectrum
In this paper, we present an analysis of the pulsating behavior of Kepler target KIC 9845907. Using the data from Kepler, we detected 85 significant frequencies, including the first overtone \\(f_1\\) = 17.597 day\\(^-1\\) as the dominant frequency, the non-radial independent frequency \\(f_3\\) = 31.428 day\\(^-1\\) (\\(\\)=1), as well as two modulation terms \\(f_m1\\) = 0.065 day\\(^-1\\) and \\(f_m2\\) = 1.693 day\\(^-1\\). We found fourteen pairs of triplet structures with \\(f_m1\\) or \\(f_m2\\), four pairs of which can further form quintuplet structures. We note these are the most intriguing features discovered in this study and they were recognized for the first time in \\(\\) Scuti stars. We discussed several possible explanations, i.e., beating, the Blazhko effect, combination mode hypothesis, nonlinear mode coupling, large separation, and stellar rotational splitting for these equidistant structures. Our asteroseismic models indicate this modulation with \\(f_m1\\) might be related to the rotational splitting. The study of more \\(\\) Scuti stars with triplet and/or quintuplet structures using high-precision space photometry would be helpful to further explore its origin.
A catalogue of double-mode high amplitude \\(\\) Scuti stars in the Galaxy and their statistical properties
We present the first catalogue of double-mode and multi-mode high amplitude \\(\\) Scuti star (HADS) in the Galaxy. The catalogue contains source name, coordinates, radial modes such as the fundamental (F, period P0), first-overtone (1O, period P1), second-overtone (2O, period P2), and the third-overtone (3O, period P3) if available, period ratios, magnitude, and the relevant literature. Totally, 155 sources were collected until March 2021, in which 142 HADS with double-mode (132 with F and 1O, and 10 with 1O and 2O), 11 triple-mode, and 2 quadruple-mode. Statistical analysis shows clear features: P0 lies in a range of 0.05 days to 0.175 days (sample: 132 double-mode HADS pulsating in F and 1O); P1/P0 lies in a range of 0.761 \\(-\\) 0.787 (sample: 142 with P0 and P1), in which about 90\\% in 0.765 \\(-\\) 0.785, which is wider than previous studies. The Petersen diagram was created with a much larger sample (144 HADS with P0 and P1) and we find that stars with periods in 0.05 \\(-\\) 0.1 days scatter largely from the updated linear relation (i.e., Eq.1), the reason of which however needs further investigation. Particularly, we discover that the ratio P2/P1 (sample: 21 HADS with P1 and P2) equals 0.802\\(\\)0.004, which could be viewed as a possible indicator to identify the modes 1O and 2O for multi-mode HADS. In addition, several unusual stars are pointed out, which may need more attention to their pulsations and stellar parameters in the future.