Deep physical structure and geotectonic implications of the eastern margin of the Qinghai–Tibet Plateau

The eastern margin of the Qinghai–Tibet Plateau (QTP) is the focus of studies on eastward lateral extrusion of the latter’s crustal material. This study aims to explore the structural response of the QTP’s eastern crust–mantle to the extrusion, and the basis for the latter’s geological structure. Data on long-period magnetotelluric sounding of cross-tectonic units and Bouguer gravity were used to determine the physical structure of the crust–mantle at the plateau’s eastern margin. The findings are as follows: (i) the apparent density structure indicates extensive presence of a low-density material in the middle–lower crusts of the Songpan and Sichuan–Yunnan blocks at the QTP’s eastern margin. On the other hand, the Yangtze cratonic block (Sichuan Basin) contains a material with a significantly higher density. To the west of the Longmenshan–Panxi tectonic zones, and along the lower crust at 40–50 km depth, is an obvious low-density zone aligned in a northeast–southwest orientation; (ii) the electrical structural model spanning Songpan block–Longmenshan tectonic zone–Yangtze block reveals three distinct electrical structural units along the cross-section bounded by the Longmenshan tectonic zone. The first is the Songpan block, which has high and low resistivity at the shallow layer and middle–lower crusts, respectively. Next is the Yangtze craton, which has low and relatively higher resistivity at the shallow layer and middle–lower crusts, respectively. Third is the Longmenshan transitional tectonic zone, whose shallow layer and deep structure are characterized by an electrical structure with a thrust nappe towards the east, and a high-conductivity material extending to the lithospheric mantle, respectively; (iii) the apparent density and electrical structures indicate that the Panxi tectonic zone has a weakened structure in the lower crust; and (iv) physical properties of the QTP’s deep structure indicate that its eastern margin may contain a middle–lower crustal fluid material with the attributes of high conductivity and low density. Its distribution is closely related to the uplift mechanism and deep seismogenic activities at the QTP’s eastern margin. Estructura profunda e implicaciones geotectónicas del margen oriental del altiplano Qinghai-Tíbet ResumenEl margen oriental del altiplano Qinghai-Tíbet (QTP, del inglés Qinghai-Tibet Plateau) es el área de la extrusión lateral hacia el Este de material cortical. Este trabajo se enfoca en explorar la respuesta estructural de las capas superiores en el altiplano y las bases para su estructuración geológica. Se utilizó información magnetotelúrica y anomalías de Bouguer para determinar la respuesta geofísica de las capas superiores en el margen occidental del altiplano. Dentro de los principales resultados se tiene: (i) la distribución de la densidad aparente indica la presencia de material de baja densidad en las capas medias y bajas de los bloques Songpan y Sichuan-Yunnan en el Este del QTP. Por otro lado, el bloque cratónico Yangtze (en la cuenca Sichuan) contiene material con una mayor densidad. Al oeste de las zonas tectónicas Longmeshan-Panxi, y a lo largo de las capas inferiores, entre 40 y 50 kilómetros de profundidad, hay una zona de baja densidad con orientación noreste-suroeste. (ii) El modelo eléctrico que abarca el bloque Songpan, la zona tectónica Longmeshan y el bloque Yangtze, revela tres unidades a lo largo de la sección cruzada subordinada a la zona tectónica Longmenshan. La primera unidad está en el bloque Songpan, con alta resistividad en la capa superficial y baja en las capas media e inferiores. Luego aparece el cratón Yangtze, con baja resistividad en la superficie y resistividad media en las capas media e inferiores. La tercera unidad es la zona tectónica transicional de Longmenshan, cuya estructura superficial y profunda está caracterizada por una estructura eléctrica asociada a una falla de cabalgamiento hacia el Este y alta conductividad de material que se extiende hacia el manto litosférico. (iii) La densidad aparente y las estructuras eléctricas indican que la zona tectónica de Panxi está debilitada en las capas inferiores. (iv) las propiedades geofísicas de la estructura profunda del altiplano Qinghai-Tíbet muestran que su margen oriental puede contener un fluido de material en las capas bajas y medias con características de alta conductividad y baja densidad. Su distribución está interrelacionada con el mecanismo de elevación y las actividades sismogénicas profundas en el margen oriental del altiplano

A Parallel Principal Skewness Analysis and Its Application in Radar Target Detection

Radar is often affected by various clutter backgrounds in complex environments, so clutter suppression has important practical significance for radar target detection. The clutter suppression process conforms to the blind source separation (BSS) model. The principal skewness analysis (PSA) algorithm is a BSS algorithm with third-order statistics as the objective function, and its running speed is faster than the conventional BSS algorithm. Still, the PSA algorithm has the problem of error accumulation. This paper improves the PSA algorithm and proposes a parallel PSA (PPSA) algorithm. PPSA can estimate the directions corresponding to each independent component simultaneously and avoid the problem of error accumulation. PPSA uses parallel instead of serial computing, significantly improving the running speed. In this paper, the PPSA algorithm is applied to radar target detection. The simulation data and real data experiments verify the effectiveness and superiority of the PPSA algorithm in suppressing clutter

An outbreak of rotavirus-related acute gastroenteritis of childcare center in Guangzhou, southern China

Rotavirus is the most common cause of severe diarrhea in children under 5 y old in the world. The study aims to explore the relationship between rotavirus vaccination and infection in the outbreak of rotavirus gastroenteritis in a childcare center. Earlier immunization and high vaccination rate should be encouraged

Hsa-miR-21 and Hsa-miR-29 in Tissue as Potential Diagnostic and Prognostic Biomarkers for Gastric Cancer

Background/Aims: Gastric cancer (GC) is the fourth most common cancer and the second most common cause of cancer deaths worldwide. Endoscopic examination is the most used method to detect the GC nowadays, whereas this method is expensive and invasive. MicroRNAs (miRNAs) are a group of recently discovered small non-protein-coding RNAs. They regulate the expression of hundreds of target genes; thereby control a wide range of tumorigenic processes. In this study, we selected two miRNAs, hsa-miR-21 and hsa-miR-29, as the targets to assess their diagnostic and prognostic value for GC. Methods: A total of 50 GC patients including 24 females and 26 males were recruited. Tumor and adjacent non-tumor tissue samples were collected from all these participants during the endoscopic examination. RNAs were extracted from these samples, then quantified via qRT-PCR and normalized with RNU43 as the internal control. Statistical analyses were conducted using the GraphPad Prism 5.0. Results: We discovered a higher expression of hsa-miR-21 and a relatively lower expression of hsa-miR-29hsa-miR-29 in the tumor tissue than in the adjacent non-tumor tissue. Moreover, both the two miRNAs showed moderate diagnostic performance (hsa-miR-21: AUC = 0.75, sensitivity = 0.70, specificity = 0.78; hsa-miR-29hsa-miR-29: AUC = 0.73, sensitivity = 0.70, specificity = 0.68). In the follow-up research, we found that higher tissue hsa-miR-21 level was related to a lower overall survival rate, whereas higher tissue hsa-miR-29hsa-miR-29 level was associated with the higher overall survival rate. These results indicated that both hsa-miR-21 and hsa-miR-29 had the potential to be the biomarkers for GC prognosis. Conclusion: In summary, we verified the diagnostic and prognostic value of tissue hsa-miR-21hsa-miR-21 and hsa-miR-29 in GC. Both of them can be potentially applied as novel and non-invasive biomarkers for GC

Spatial Path Planning for Robotic Milling of Automotive Casting Components Based on Optimal Machining Posture

The robotic milling of automotive casting components can effectively reduce human participation in the production process and enhance production efficiency and quality, but the premise addresses the reasonable planning of machining paths. To address major challenges, this paper proposes a spatial path planning method for the robotic milling of casting flash and burrs on an automotive engine flywheel shell based on the optimal machining posture. Firstly, an improved stereolithography slicing algorithm in arbitrary tangent plane direction is put forward, which solves the problem that the existing stereolithography slicing algorithm cannot accurately extract the contour of complex components. Secondly, the contour path curve fitting of the slicing points of the flywheel shell is realized based on the B-spline curve. Next, a machining posture evaluation function is established based on the robot’s stiffness performance, and the optimal machining posture is solved and verified with simulation according to the machining posture evaluation function and posture interpolation. Finally, the experiments indicate that the proposed method can significantly enhance the machining quality, with an average allowance height of 0.33 mm, and reduce the machining time to 9 min, compared with the conventional manual operation, both of which satisfy the machining requirements