Crustal structure and deformation beneath the NE margin of the Tibetan plateau constrained by teleseismic receiver function data

We analysed a large amount of teleseismic receiver function data recorded by 172 broadband stations in the NE Tibetan plateau and its surrounding areas to investigate the crustal velocity and anisotropy structure beneath the margin. We first applied the modified H–κ stacking technique to measure the crustal thickness and average Vp/Vs ratio, and then employed a joint inversion scheme to measure azimuthal anisotropy of the crust beneath each station. The observed crustal thickness and Vp/Vs ratio exhibit large variations across the study area, varying from 32 to 75.6 km and from 1.601 to 1.864, respectively. We also found significant azimuthal anisotropy within the crust beneath 12 stations, with a splitting time between 0.36 and 1.06s. The fast polarization directions align well with surface structures, and follow the directions of the maximum horizontal tensile stress. The low Vp/Vs ratio and the strong azimuthal anisotropy observed beneath the margin suggest that whole crustal shortening might be the dominant mechanism for producing the thick crust in NE Tibet. We compared the measured seismic anisotropy with those measured from XKS (SKS, PKS and SKKS), and found that crustal anisotropy appears to play an important role in explaining the amount of XKS splitting times. More importantly, the Moho Ps and the XKS share similar fast polarization directions, suggesting a vertically coherent deformation within the lithosphere beneath the margin

Predicting Microsatellite Instability Status in Colorectal Cancer Based on Triphasic Enhanced Computed Tomography Radiomics Signatures: A Multicenter Study

BackgroundThis study aimed to develop and validate a computed tomography (CT)-based radiomics model to predict microsatellite instability (MSI) status in colorectal cancer patients and to identify the radiomics signature with the most robust and high performance from one of the three phases of triphasic enhanced CT.MethodsIn total, 502 colorectal cancer patients with preoperative contrast-enhanced CT images and available MSI status (441 in the training cohort and 61 in the external validation cohort) were enrolled from two centers in our retrospective study. Radiomics features of the entire primary tumor were extracted from arterial-, delayed-, and venous-phase CT images. The least absolute shrinkage and selection operator method was used to retain the features closely associated with MSI status. Radiomics, clinical, and combined Clinical Radiomics models were built to predict MSI status. Model performance was evaluated by receiver operating characteristic curve analysis.ResultsThirty-two radiomics features showed significant correlation with MSI status. Delayed-phase models showed superior predictive performance compared to arterial- or venous-phase models. Additionally, age, location, and carcinoembryonic antigen were considered useful predictors of MSI status. The Clinical Radiomics nomogram that incorporated both clinical risk factors and radiomics parameters showed excellent performance, with an AUC, accuracy, and sensitivity of 0.898, 0.837, and 0.821 in the training cohort and 0.964, 0.918, and 1.000 in the validation cohort, respectively.ConclusionsThe proposed CT-based radiomics signature has excellent performance in predicting MSI status and could potentially guide individualized therapy

Clinical meaning of serum trimethylamine oxide, N-terminal-pro-brain natriuretic peptide, hypoxia-inducible factor-1a and left ventricular function and pregnancy outcome in patients with pregnancy-induced hypertension

Background: To figure out the clinical meaning of serum trimethylamine oxide (TMAO), N-terminal-pro-brain natriuretic peptide (NT-proBNP) and hypoxia-inducible factor-1a (HIF-1a) with left ventricular function and pregnancy outcome in patients with pregnancy-induced hypertension. Methods: From January 2018 to October 2020, 117 patients with gestational hypertension were taken as the research objects and grouped into the gestational hypertension (pregnancy-induced hypertension, 55 cases), mild preeclampsia (mild PE, 43 cases) and severe preeclampsia (severe PE, 19 cases) in the light of the severity of the disease. Analysis of the relation of serum TMAO, NT-proBNP and HIF-1a with the severity of disease and cardiac function indexes in patients with gestational hypertension was conducted. All patients were followed up to the end of pregnancy, and the predictive value of serum TMAO, NT-proBNP and HIF-1a on pregnancy outcome in patients was analyzed. Results: Serum TMAO and NT-proBNP of patients were elevated, while HIF-1a was reduced with the severity of the disease (P < 0.05). Serum TMAO and NT-proBNP in patients with gestational hypertension were positively correlated but HIF-1a was negatively correlated with the severity of the disease (P < 0.05). Left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV) were elevated in gestational hypertension patients, while ejection fraction (LVEF) was reduced with the severity of disease (P < 0.05). Serum TMAO, NT-proBNP and HIF1a were associated with LVEDV, LVESV and LVEF values in patients with gestational hypertension (P < 0.05). Serum TMAO and NT-proBNP were elevated but HIF-1a was reduced in patients with a poor pregnancy outcome (P < 0.05). The AUC of the combined detection of serum TMAO, NT-proBNP and HIF-1a on pregnancy outcome was greater (P < 0.05). Conclusions: Serum TMAO, NT-proBNP and HIF-1a in patients with gestational hypertension are associated with disease severity and cardiac function, and have predictive and evaluative values for disease severity and pregnancy outcome

Origin of plagioclase-olivine inclusions

Plagioclase-Olivine Inclusions (POIs) are an abundant group of chondrule-like objects found in carbonaceous chondrites. Despite textural evidence of a molten or partially molten origin, approximately half of the POls studied exhibited variations in Mg isotope composition of up to 11 %/amu between spinel and coexisting silicates. Equilibrium crystallization experiments performed to study the crystallization behavior of melts of POI compositions showed that the phase assemblages predicted on the basis of phase equilibria are generally consistent with those observed in POIs. Spinel is the liquidus phase for most of the inclusions that contain spinel with fractionated Mg isotopes, and therefore these spinels could be preserved if melting was below the liquidus temperature for the bulk composition of the inclusion. The presence of resorbed spinels in some inclusions whose bulk composition does not permit spinel in its phase assemblage requires that these spinels were relict. The petrographic and chemical properties of POIs indicate that they are not condensates or evaporative residues, but formed by melting or partial melting of pre-existing solids that had originated from isotopically distinct reservoirs. The presence of isotopically heterogeneous spinel in the POIs requires that the maximum temperature experienced by these objects was low enough, the duration of heating short enough, and the subsequent cooling rate fast enough to prevent homogenization of Mg isotopes by diffusive transport. The self-diffusion rate of Mg was measured in spinel and coexisting melt using isotope tracers. For spinel, the activation energy of 384±7 kJ for Mg and pre-exponential factor of 7791.9±1.3 cm^2/s is obtained. The temperatures of melting of POIs is estimated to be in the range of 1350-1500°C, the duration of the heating events were 25°/hr. The melting occurred after most ^(26)Al had decayed and possibly subsequent to the extensive oxygen isotopic exchange between solids and nebula gas. The melting of POIs is probably by flash heating or impact melting in a hot parcel or region of the nebula. These refractory objects (including CAIs) are believed to be the result of repetitive heating events that had frequently generated or reprocessed refractory residues over a prolonged timescale of very early solar system history

Study on Cracking Resistance of Basalt Fiber-Reinforced Microbond Asphalt Macadam

The aim of the present study was to explore the effect of basalt fibers on the cracking resistance of microbond asphalt macadam and reduce the occurrence of cracks in asphalt pavements with semirigid base. To this end, compressive resilient modulus tests, rutting tests, and semicircular bending tests were conducted on microbond asphalt macadam with different fiber contents, and the change trends of the compressive resilient modulus, dynamic stability, and flexibility index (FI) with fiber content were revealed. According to the results of this study, the addition of basalt fibers affected the compressive resilient modulus, dynamic stability, and FI of microbond asphalt macadam significantly. With the increase of fiber content, the compressive resilient modulus, dynamic stability, and FI presented a uniform trend of increasing first and decreasing afterwards. When the fiber content was 0.4%, various indices reached their maximum values, suggesting that the cracking resistance of the basalt fiber-reinforced microbond asphalt macadam was optimal under this content. This study is of great significance for the application and promotion of basalt fiber-reinforced microbond asphalt macadam

Shear Lag Effect and Accordion Effect on Dynamic Characteristics of Composite Box Girder Bridge with Corrugated Steel Webs

This study proposed a dynamic characteristic analytical method (ANM) of a composite box girder bridge with corrugated steel web (CBGCSW) by completely considering the impact of shear lag effect and accordion effect of corrugated steel webs. Based on energy principles and variational principles, a vibration differential equation and the natural boundary conditions of a CBGCSW were developed. The analytical calculation formula for solving the vibration differential equation was then obtained. The results calculated using the ANM agreed well with previous experimental results, which validated the correctness of ANM. To demonstrate the superiority of the ANM, the vibration frequencies of several abstract CBGCSWs with varying ratios of span&ndash;width, obtained using the elementary beam theory (EBT) and the finite element method (FEM), were compared with those obtained by ANM. The efficacy of the ANM was verified and some meaningful conclusions were drawn which are helpful to relevant engineering design, such as the observation that a higher natural vibration frequency and smaller span&ndash;width ratio significantly magnified the shear lag effect of CBGCSW. The first five-order natural vibration frequencies of the CBGCSW were significantly lower than those of the composite box girder bridge with general steel web (CBGGSW), which indicates that the impact of the accordion effect is significant