A method for extracting the preseismic gravity anomalies over the Tibetan Plateau based on the maximum shear strain using GRACE data

The occurrence of earthquakes is closely related to the crustal geotectonic movement and the migration of mass,which consequently cause changes in gravity.The Gravity Recovery And Climate Experiment(GRACE)satellite data can be used to detect gravity changes associated with large earthquakes.However,previous GRACE satellite-based seismic gravity-change studies have focused more on coseismic gravity changes than on preseismic gravity changes.Moreover,the noise of the north–south stripe in GRACE data is difficult to eliminate,thereby resulting in the loss of some gravity information related to tectonic activities.To explore the preseismic gravity anomalies in a more refined way,we first propose a method of characterizing gravity variation based on the maximum shear strain of gravity,inspired by the concept of crustal strain.The offset index method is then adopted to describe the gravity anomalies,and the spatial and temporal characteristics of gravity anomalies before earthquakes are analyzed at the scales of the fault zone and plate,respectively.In this work,experiments are carried out on the Tibetan Plateau and its surrounding areas,and the following findings are obtained:First,from the observation scale of the fault zone,we detect the occurrence of large-area gravity anomalies near the epicenter,oftentimes about half a year before an earthquake,and these anomalies were distributed along the fault zone.Second,from the observation scale of the plate,we find that when an earthquake occurred on the Tibetan Plateau,a large number of gravity anomalies also occurred at the boundary of the Tibetan Plateau and the Indian Plate.Moreover,the aforementioned experiments confirm that the proposed method can successfully capture the preseismic gravity anomalies of large earthquakes with a magnitude of less than 8,which suggests a new idea for the application of gravity satellite data to earthquake research.

人参皂甙Rg3对人喉鳞癌Hep-2细胞分泌性VEGF的影响(英文)

Objective: The aim of this study was to investigate the affecting of Rg3 to secreted VEGF of human laryngeal carcinoma Hep-2 cells and its mechanism of inhibition to tumor angiogenesis. Methods: Cultured human laryngeal cancer cell line Hep-2 and human vascular endothelial cells in vitro, cells got into the period of exponential phase of growth, was diviced into 3 groups: group I(control group), group II(DDP group), group III(Rg3 group). Added to the Hep-2 cells Rg3 and DDP, made Rg3 final concentration was 300 μg/mL, and DDP was 3 μg/mL. 48 h later, specimens from sample to be done immunocytochemistry, and the protein of VEGF in Hep-2 cells to be detected. Collecting Hep-2 cells supernatant, some was used to measure the protein level of VEGF in Hep-2 cells supernatant by ELISA. Some was used to culture HVEC. 24 h later,cell growth inhibition rate of human vascular endothelial was determined by MTT. Results: The protein level of VEGF was evidently higher in group I compared to group II and group III, it was not only in Hep-2 cells, but also in supernatant of Hep-2 cells.There was no significantly different between group II and group III. MTT results showed that, the human vascular endothelial cell growth inhibition rate of group I was significantly lower than that of group II and group III(P < 0.05). At the same time the HVEC growth inhibition rate of group II was significantly lower than that of group III(P < 0.05). Conclusion: The inhibition to tumor angiogenesis of Rg3 is stronger than traditional chemotherapy drug cisplatin. It worke by reducing the biological effects of secreted VEGF, But the effecting worke by reducing the activity of secreted VEGF itself or affecting endothelial function of VEGF receptor or some other ways to be further studied.

Desertification evolution prediction for lake area of Minqin oasis based on integration of GIS and cellular automata

The Minqin oasis is surrounded on three sides by the Tengger Desert and the Badanjilin Desert, and it prevents these two deserts from converging. However, in recent years it has become the worst ecological environment in the Lake area due to deficient water resources, continual declines in the groundwater level and quality （increasing mineralization and salination）, which are causing in- creasing desertification. In this study, Landsat Thematic Mapper （TM） remote images from 1992, 1998, 2002, and 2006 of the Lake area of the Minqin oasis are interpreted to analyze the desertification evolution. A combination of an ArcObjects module and a cellular automata model is used to build a model simulating the desertification dynamics; the forecasting accuracy of this model is shown to reach up to 90%. The desertification situation in 2012 is forecasted by this model, and the results showed that, from 2006 to 2012, the green land area will be reduced by 999.92 hm2 （l.59 percent of the total oasis area）, the desertification land area will be reduced by 3,000.68 hrn2 （4.78 percent of the total oasis area）, and sand land area will increase by 4,000.6 hm2 （6.37 per- cent of the total oasis area）. The sand land is predicted to become more widespread, and more than 18% sand land will be distrib- uted in the center of green land in the Lake area. In other words, more and more abandoned green land （mined farm land） will be transformed into sand land, and this will intensify the desertification.

低氧条件下γ射线对Hep-2细胞周期、凋亡的影响(英文)

Objective: The aim of the study was to investigate the impact of 60Co γ-ray on apoptosis, cell cycles and the expression of protein hypoxia-inducible factor-1α (HIF-1α) to Hep-2 cell line in the conditions of normoxia and hypoxia. Methods: Hep-2 cell were divided into 2 groups: group A (normoxia) and group B (hypoxia). All of the cells were exposed to γ-ray with dosage being 0, 1, 3, 5, 10, 20, and 40 Gy. Flow cytometry was used to measure the protein level of HIF-1α and to detect apoptosis and cell cycles. The protein level of HIF-1α was also determined by immunohistochemistry and Western blotting. Results: The protein level of HIF-1α in group B was significantly higher than that in group A. In group A, low doses (1-5 Gy) of γ-ray had caused G0/G1 cell cycle arrest and high doses (10-40 Gy) had caused G2/M cell cycle arrest. In group B, without exposure of γ-ray (0 Gy) had caused G0/G1 cell cycle arrest, all of the different dosage of γ-ray could cause G2/M cell cycle arrest. The curve of apoptosis rate in group A was a parabola, the apoptotic rate was related to the dosage of γ-ray in a dosage dependent manner. The peak was at the point of 5 Gy. The apoptosis rate in group A was significantly higher than that in group B. Conclusion: Different doses of γ-ray could cause different cell cycles arrest then make different impact on apoptosis to Hep-2 cell. The lower apoptosis rate in condition of hypoxia maybe has a relationship with G2/M cell cycle arrest. Up-regulated HIF-1α protein may be one of the reasons for G2/M cell cycle arrest.