494 research outputs found
3D Magneto-Hydrodynamic Simulations of Parker Instability with Cosmic Rays
This study investigates Parker instability in an interstellar medium (ISM)
near the Galactic plane using three-dimensional magneto-hydrodynamic
simulations. Parker instability arises from the presence of a magnetic field in
a plasma, wherein the magnetic buoyant pressure expels the gas and cause the
gas to move along the field lines. The process is thought to induce the
formation of giant molecular clouds in the Galaxy. In this study, the effects
of cosmic-ray (CR) diffusion are examined. The ISM at equilibrium is assumed to
comprise a plasma fluid and a CR fluid at various temperatures, with a uniform
magnetic field passing through it in the azimuthal direction of the Galactic
disk. After a small perturbation, the unstable gas aggregates at the footpoint
of the magnetic fields and forms dense blobs. The growth rate of the
instability increases with the strength of the CR diffusion. The formation of
dense clouds is enhanced by the effect of cosmic rays (CRs), whereas the shape
of the clouds depends sensitively on the initial conditions of perturbation.Comment: 4 pages, Computer Physics Communications 2011, 182, p177-17
The Ethanol Extract of Fructus trichosanthis Promotes Fetal Hemoglobin Production via p38 MAPK Activation and ERK Inactivation in K562 Cells
Pharmacological stimulation of fetal hemoglobin (HbF) expression may be a promising approach for the treatment of beta-thalassemia. In this study, the effects of Fructus trichosanthis (FT) were investigated in human erythroleukemic K562 cells for their gamma-globin mRNA and HbF-induction activities. The role of signaling pathways, including extracellular regulated protein kinase (ERK) and p38 mitogen-activated protein kinase (MAPK), was also investigated. It was found that the ethanol extract of FT significantly increased gamma-globin mRNA and HbF levels, determined by real-time reverse transcription polymerase chain reaction and enzyme linked immunosorbent assay, respectively, in dose- and time-dependent manner. Total Hb (THb) levels were also elevated in the concentrations without cytotoxicity (<80 μg mL−1). Pre-treatment with p38 MAPK inhibitor SB203580 blocked the stimulatory effects of FT extract in total and HbF induction. In contrast, no change in HbF was observed when treated with ERK inhibitor PD98059. Furthermore, FT ethanol extract activated p38 MAPK and inhibited ERK signaling pathways in K562 cells, as revealed in western blotting analysis. In addition, SB203580 significantly abolished p38 MAPK activation when the cells were treated with FT. In summary, the ethanol extract of FT was found to be a potent inducer of HbF synthesis in K562 cells. The present data delineated the role of ERK and p38 MAPK signaling as molecular targets for pharmacologic stimulation of HbF production upon FT treatment
A Study of Three Sectors Employment Effects Resulting from Foreign Direct Investment- Empirical Analysis on the Data from Shanghai
With the development of China's reform policy, China's economy has integrating into the global economy. As a result, more and more foreign capital continues to flow into China. Since 1990, foreign direct investment (FDI) was mainly concentrated in the Yangtze River Delta region, and Shanghai enjoyed strong economic strength, thanks to its abundant human resources and convenient transportation network; as these are excellent qualities for attracting foreign investment, Shanghai became one of the major cities attracting FDI. FDI has had a tremendous impact on many aspects in Shanghai, including employment. Therefore, Shanghai was chosen as the research object of this paper. This paper is organized as follows. Firstly, a theoretical analysis of the employment effects of FDI is presented. Secondly, after combining the actual utilization of FDI and employment in Shanghai, an empirical analysis of the effects of FDI on employment's quantity, employment's distribution and employment quality is carried out by collecting relevant data and establishing regression models. This study finds that while FDI does exert a positive influence on the quantity of employment in Shanghai's tertiary industry, it is not conducive to primary and secondary industries. In addition, FDI has shown positive and negative impacts on the quality of employment. Lastly, some suggestions are proposed to enhance the positive role of FDI on employment
Application of Ground LiDAR for The Investigation of Outcrop Discontinuities and Estimation of Associated Engineering Characteristics
Reliable and direct information about rock slope materials and discontinuity parameters from field investigation are keys to engineering design, structure maintenance and soil/water conservation. Under the impact of global climate change and the surge in extreme weather events, rapid and accurate equipment or procedures for geological engineering surveys are necessary to harmonize engineering facilities with natural environment. This study utilizes 3D laser scanning technology (also known as ground LiDAR), which obtains the coordinates of surface geometry rapidly in point clouds, to survey two outcrops. Applying ground LiDAR in a geological survey, we compare the results with those provided by the International Society of Rock Mechanics, and analyze the slope stability. This study also discusses the applicability and limitations of ground LiDAR technology in discontinuity investigation and estimation of rock mass engineering characteristics. Suggested operating procedures for the use of ground LiDAR technology in outcrop surveys are provided accordingly. The results show that ground LiDAR technology reduces the in-situ operation time significantly, thus facilitating efficient discontinuity surveys and outcrop parameters evaluation. However, the quantities of office work and the accuracy of point clouds depend on the velocity and accuracy of ground LiDAR surveys. Therefore, inspection of survey results and output parameter, along with the application and operating specifications of geological surveys, including point cloud resolution, reasonable error of superimposition, inspection procedures and data analysis, still await further research.岩石工程道路邊坡經現地調查獲得可靠、直接的岩石材料種類與不連續面參數,為確保工程設計施工、設施營運維護及環境水土保持之關鍵資訊。在近年全球氣候變遷與極端氣候事件規模與頻率加大的衝擊下,迅速、精準的工程地質調查工具與作業方法,為落實工程設施與自然環境永續發展的不二法門。本研究利用三維雷射掃描技術 (又稱光達技術,|iDAR),運用其可快速取得露頭表面幾何坐標描述點雲的特性,透過2處露頭現地地質調查,探討地面光達在工址地質調查之應用,並比較國際岩石力學學會建議工址現地調查作業方法所獲得的參數,分析評估邊坡的穩定特性,據以提出地面光達應用於露頭不連續面調查與岩體工程特性評估的適用性與限制,並提出地面光達應用於露頭調查的作業程序。研究結果顯示,地面光達技術可大幅縮減現地調查作業時間,為露頭不連續面調查與參數評估的新利器,由於室內分析工作量和點雲的精度決定了|iDAR應用於露頭不連續面調查的速度與精準度,未來針對調查成果與產出參數的檢核、在地質調查的應用與作業規範,包括點雲解析度、疊合容許誤差以及資料分析與檢核程序等,有待進一步深入研究
Nuclear Export Signal Mutation of Epidermal Growth Factor Receptor Enhances Malignant Phenotypes of Cancer Cells
Nuclear epidermal growth factor receptor (EGFR) has been shown to be correlated with drug resistance and a poor prognosis in patients with cancer. Previously, we have identified a tripartite nuclear localization signal (NLS) within EGFR. To comprehensively determine the functions and underlying mechanism of nuclear EGFR and its clinical implications, we aimed to explore the nuclear export signal (NES) sequence of EGFR that is responsible for interacting with the exportins. We combined in silico prediction with site-directed mutagenesis approaches and identified a putative NES motif of EGFR, which is located in amino acid residues 736-749. Mutation at leucine 747 (L747) in the EGFR NES led to increased nuclear accumulation of the protein via a less efficient release of the exportin CRM1. Interestingly, L747 with serine (L747S) and with proline (L747P) mutations were found in both tyrosine kinase inhibitor (TKI)-treated and -naïve patients with lung cancer who had acquired or de novo TKI resistance and a poor outcome. Reconstituted expression of the single NES mutant EGF
Clonal evolution and clinical implications of genetic abnormalities in blastic transformation of chronic myeloid leukaemia
Blast crisis (BC) predicts dismal outcomes in patients with chronic myeloid leukaemia (CML). Although additional genetic alterations play a central role in BC, the landscape and prognostic impact of these alterations remain elusive. Here, we comprehensively investigate genetic abnormalities in 136 BC and 148 chronic phase (CP) samples obtained from 216 CML patients using exome and targeted sequencing. One or more genetic abnormalities are found in 126 (92.6%) out of the 136 BC patients, including the RUNX1-ETS2 fusion and NBEAL2 mutations. The number of genetic alterations increase during the transition from CP to BC, which is markedly suppressed by tyrosine kinase inhibitors (TKIs). The lineage of the BC and prior use of TKIs correlate with distinct molecular profiles. Notably, genetic alterations, rather than clinical variables, contribute to a better prediction of BC prognosis. In conclusion, genetic abnormalities can help predict clinical outcomes and can guide clinical decisions in CML
Incidence of oral cancer in relation to nickel and arsenic concentrations in farm soils of patients' residential areas in Taiwan
<p>Abstract</p> <p>Background</p> <p>To explore if exposures to specific heavy metals in the environment is a new risk factor of oral cancer, one of the fastest growing malignancies in Taiwan, in addition to the two established risk factors, cigarette smoking and betel quid chewing.</p> <p>Methods</p> <p>This is an observational study utilized the age-standardized incidence rates of oral cancer in the 316 townships and precincts of Taiwan, local prevalence rates of cigarette smoking and betel quid chewing, demographic factors, socio-economic conditions, and concentrations in farm soils of the eight kinds of heavy metal. Spatial regression and GIS (Geographic Information System) were used. The registration contained 22,083 patients, who were diagnosed with oral cancer between 1982 and 2002. The concentrations of metal in the soils were retrieved from a nation-wide survey in the 1980s.</p> <p>Results</p> <p>The incidence rate of oral cancer is geographically related to the concentrations of arsenic and nickel in the patients' residential areas, with the prevalence of cigarette smoking and betel quid chewing as controlled variables.</p> <p>Conclusions</p> <p>Beside the two established risk factors, cigarette smoking and betel quid chewing, arsenic and nickel in farm soils may be new risk factors for oral cancer. These two kinds of metal may involve in the development of oral cancer. Further studies are required to understand the pathways via which metal in the farm soils exerts its effects on human health.</p
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