Neutral beam current drive in a tokamak

Neutral beam current drive (NBCD) on the EAST tokamak is studied by using Monte-Carlo simulation. The electron shielding effect to the fast ion current is taken into account by using a fitting formula applicable to general tokamak equilibria and arbitrary collisionality regime. The net currents driven by the beam are off-axis although the fast ion currents are on-axis. This is found to be due to the electron shielding effect being strong near the magnetic axis. We also investigate the dependence of NBCD efficiency on the plasma density. The results indicate that the NBCD efficiency decreases with the increase in plasma density. A simple semi-analytic estimation of the dependence of NBCD efficiency on the density is proposed and is in reasonable agreement with the results directly obtained in the simulations

Expression and aberrant promoter methylation of Wnt inhibitory factor-1 in human astrocytomas

<p>Abstract</p> <p>Background</p> <p>Wnt inhibitory factor-1(WIF-1) acts as a Wnt-antagonists and tumor suppressor, but hypermethylation of WIF-1 gene promoter and low expression activate Wnt signaling aberrantly and induce the development of various human tumors. With this work we intended to investigate the expression and promoter methylation status of WIF-1 gene in human astrocytomas.</p> <p>Methods</p> <p>The tissue samples consisted of 53 astrocytomas and 6 normal brain tissues. The expression levels of WIF-1 were determined by immunohistochemistry and semiquantitative RT-PCR. The results were analyzed in correlation with clinicopathological data. Methylation status of WIF-1 gene promoter was investigated using methylation specific PCR. The relationship between methylation and expression of the genes was analyzed.</p> <p>Results</p> <p>The average expression levels of WIF-1 protein and mRNA in astrocytomas were decreased significantly compared with normal control tissues. The protein and mRNA expression of WIF-1 gene in astrocytomas was decreased with the increase of pathological grade. Furthermore, WIF-1 promoter methylation was observed by MS-PCR in astrocytomas which showed significant reduction of WIF-1 expression. The WIF-1 promoter hypermethylation was associated with reduced expression of WIF-1 expression.</p> <p>Conclusion</p> <p>Our results demonstrate that the WIF-1 gene is frequently down-regulated or silenced in astrocytomas by aberrant promoter methylation. This may be an important mechanism in astrocytoma carcinogenesis.</p

Assessing the Treatment Effect on the Causal Models via Parametric Approaches with Applications to the Study of English Educational Effect in Japan

Observational studies are widely used to evaluate the effect of treatment when it is not feasible to conduct controlled experiment. This article considers the use of parametric analyses for estimating the causal treatment effect. The proposed approach is an alternative to the widely used stratification estimator as well as Robins' double robust estimator both of which are consistent under the key assumption of strong ignorability. To relax the assumption of strong ignorability, we instead impose fully parametric structures on the causal models to identify the causal treatment effect. The proposed parametric framework provides a likelihood ratio test for checking the assumption of strong ignorability. Simulations are conducted to investigate the performance of the proposed estimator as well as the power of the likelihood ratio test. We demonstrate how the proposed method can be used for data from an observational study for measuring English educational effect on Japanese elementary school students

Assessing the Treatment Effect on the Causal Models via Parametric Approaches with Applications to the Study of English Educational Effect in Japan

Observational studies are widely used to evaluate the effect of treatment when it is not feasible to conduct controlled experiment. This article considers the use of parametric analyses for estimating the causal treatment effect. The proposed approach is an alternative to the widely used stratification estimator as well as Robins' double robust estimator both of which are consistent under the key assumption of strong ignorability. To relax the assumption of strong ignorability, we instead impose fully parametric structures on the causal models to identify the causal treatment effect. The proposed parametric framework provides a likelihood ratio test for checking the assumption of strong ignorability. Simulations are conducted to investigate the performance of the proposed estimator as well as the power of the likelihood ratio test. We demonstrate how the proposed method can be used for data from an observational study for measuring English educational effect on Japanese elementary school students

Expression Patterns of ABA and GA Metabolism Genes and Hormone Levels during Rice Seed Development and Imbibition: A Comparison of Dormant and Non-Dormant Rice Cultivars

Seed dormancy is an important agronomic trait in cereals. Using deep dormant (N22), medium dormant (ZH11), and non-dormant (G46B) rice cultivars, we correlated seed dormancy phenotypes with abscisic acid (ABA) and gibberellin (GA) metabolism gene expression profiles and phytohormone levels during seed development and imbibition. A time course analysis of ABA and GA content during seed development showed that N22 had a high ABA level at early and middle seed developmental stages, while at late developmental stage it declined to the level of ZH11; however, its ABA/GA ratio maintained at a high level throughout seed development. By contrast, G46B had the lowest ABA content during seed development though at early developmental stage its ABA level was close to that of ZH11, and its ABA/GA ratio peaked at late developmental stage that was at the same level of ZH11. Compared with N22 and G46B, ZH11 had an even and medium ABA level during seed development and its ABA/GA ratio peaked at the middle developmental stage. Moreover, the seed development time-point having high ABA/GA ratio also had relatively high transcript levels for key genes in ABA and GA metabolism pathways across three cultivars. These indicated that the embryo-imposed dormancy has been induced before the late developmental stage and is determined by ABA/GA ratio. A similar analysis during seed imbibition showed that ABA was synthesized in different degrees for the three cultivars. In addition, water uptake assay for intact mature seeds suggested that water could permeate through husk barrier into seed embryo for all three cultivars; however, all three cultivars showed distinct colors by vanillin-staining indicative of the existence of flavans in their husks, which are dormancy inhibition compounds responsible for the husk-imposed dormancy

PROTECTIVE EFFECTS OF CISTANCHES HERBA AQUEOUS EXTRACT ON CISPLATIN-INDUCED PREMATURE OVARIAN FAILURE IN MICE

Background: Chemotherapeutic treatment of premenopausal women has been linked to premature ovarian failure (POF). Cistanches Herba (CH) is a commonly used male impotence and female infertility treatment in China; however, whether CH protects ovaries from chemotherapeutic drug-induced POF remains unclear. In this study, we investigated the protective effects of CH in a mouse model of chemotherapeutic drug-induced POF. Materials and Methods: We administered low- and high-concentration CH to cisplatin-induced POF mice for 2 weeks and determined body and ovarian weights, as well as serum follicle-stimulating hormone (FSH) and estradiol concentrations, to evaluate ovarian function. In addition, we evaluated the protective mechanisms of CH by detecting the levels of apoptosis-related proteins and evaluating markers of mitochondrial function. Results: In POF mice, we observed reduced body and ovarian weights; elevated serum FSH and attenuated estradiol concentrations; apoptosis of ovarian granulosa with concomitant changes in apoptosis-related proteins (including caspase-3, poly adenosine diphosphate-ribose polymerase, Bcl-2, and Bax); and mitochondrial dysfunction, such as a reduction in mitochondrial numbers, destruction of ultrastructural morphology, decrease in ATPase activity, and decreases in mitochondrial membrane potential and mitofusin-2 (a mitochondria dynamin-like GTPase). Significantly, CH reversed, to an extent, functional and morphologic injuries and ovarian tissue apoptosis by up-regulating the level of Mfn2 and the ratio of Bcl-2/Bax. Furthermore, CH reduced cisplatin-induced mitochondrial dysfunction in ovarian tissues. Conclusion: The present findings showed that CH inhibited cisplatin-induced POF through interactions between Mfn2 and Bcl-2/Bax proteins and, possibly, by up-regulation of Mfn2 expression. Ultimately, CH protects ovarian tissues from cisplatin-induced apoptosis