1,341 research outputs found

    A Microcantilever-based Gas Flow Sensor for Flow Rate and Direction Detection

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    The purpose of this paper is to apply characteristics of residual stress that causes cantilever beams to bend for manufacturing a micro-structured gas flow sensor. This study uses a silicon wafer deposited silicon nitride layers, reassembled the gas flow sensor with four cantilever beams that perpendicular to each other and manufactured piezoresistive structure on each micro-cantilever by MEMS technologies, respectively. When the cantilever beams are formed after etching the silicon wafer, it bends up a little due to the released residual stress induced in the previous fabrication process. As air flows through the sensor upstream and downstream beam deformation was made, thus the airflow direction can be determined through comparing the resistance variation between different cantilever beams. The flow rate can also be measured by calculating the total resistance variations on the four cantilevers.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/16838

    Strategies used as spectroscopy of financial markets reveal new stylized facts

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    We propose a new set of stylized facts quantifying the structure of financial markets. The key idea is to study the combined structure of both investment strategies and prices in order to open a qualitatively new level of understanding of financial and economic markets. We study the detailed order flow on the Shenzhen Stock Exchange of China for the whole year of 2003. This enormous dataset allows us to compare (i) a closed national market (A-shares) with an international market (B-shares), (ii) individuals and institutions and (iii) real investors to random strategies with respect to timing that share otherwise all other characteristics. We find that more trading results in smaller net return due to trading frictions. We unveiled quantitative power laws with non-trivial exponents, that quantify the deterioration of performance with frequency and with holding period of the strategies used by investors. Random strategies are found to perform much better than real ones, both for winners and losers. Surprising large arbitrage opportunities exist, especially when using zero-intelligence strategies. This is a diagnostic of possible inefficiencies of these financial markets.Comment: 13 pages including 5 figures and 1 tabl

    A M\"ossbauer study of the magneto-structural coupling effect in SrFe2_2As2_2 and SrFeAsF

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    In the present paper, we report a comparison study of SrFe2_2As2_2 and SrFeAsF using M\"ossbauer spectroscopy. The temperature dependence of the magnetic hyperfine field is fitted with a modified Bean-Rodbell model. The results give much smaller magnetic moment and magneto-structural coupling effect for SrFeAsF, which may be understood as due to different inter-layer properties of the two compounds.Comment: 4 pages, 2 figures,conference ICAME2011, to be appear in Hyperfine Interaction

    The Effect of Interface Texture on Exchange Biasing in Ni80Fe20/Ir20Mn80System

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    Exchange-biasing phenomenon can induce an evident unidirectional hysteresis loop shift by spin coupling effect in the ferromagnetic (FM)/antiferromagnetic (AFM) interface which can be applied in magnetoresistance random access memory (MRAM) and recording-head applications. However, magnetic properties are the most important to AFM texturing. In this work, top-configuration exchange-biasing NiFe/IrMn(x Å) systems have been investigated with three different conditions. From the high-resolution cross-sectional transmission electron microscopy (HR X-TEM) and X-ray diffraction results, we conclude that the IrMn (111) texture plays an important role in exchange-biasing field (Hex) and interfacial exchange energy (Jk).HexandJktend to saturate when the IrMn thickness increases. Moreover, the coercivity (Hc) dependence on IrMn thickness is explained based on the coupling or decoupling effect between the spins of the NiFe and IrMn layers near the NiFe/IrMn interface. In this work, the optimal values forHexandJkare 115 Oe and 0.062 erg/cm2, respectively

    IFNβ Protects Neurons from Damage in a Murine Model of HIV-1 Associated Brain Injury.

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    Infection with human immunodeficiency virus-1 (HIV-1) causes brain injury. Type I interferons (IFNα/β) are critical mediators of any anti-viral immune response and IFNβ has been implicated in the temporary control of lentiviral infection in the brain. Here we show that transgenic mice expressing HIV-1 envelope glycoprotein 120 in their central nervous system (HIVgp120tg) mount a transient IFNβ response and provide evidence that IFNβ confers neuronal protection against HIVgp120 toxicity. In cerebrocortical cell cultures, neuroprotection by IFNβ against gp120 toxicity is dependent on IFNα receptor 1 (IFNAR1) and the β-chemokine CCL4, as IFNAR1 deficiency and neutralizing antibodies against CCL4, respectively, abolish the neuroprotective effects. We find in vivo that IFNβ mRNA is significantly increased in HIVgp120tg brains at 1.5, but not 3 or 6 months of age. However, a four-week intranasal IFNβ treatment of HIVgp120tg mice starting at 3.5 months of age increases expression of CCL4 and concomitantly protects neuronal dendrites and pre-synaptic terminals in cortex and hippocampus from gp120-induced damage. Moreover, in vivo and in vitro data suggests astrocytes are a major source of IFNβ-induced CCL4. Altogether, our results suggest exogenous IFNβ as a neuroprotective factor that has potential to ameliorate in vivo HIVgp120-induced brain injury

    Development of a LAMP assay for detection of Leishmania infantum infection in dogs using conjunctival swab samples

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    Background: Leishmania infantum infections in dogs play a crucial role in the transmission of pathogens causing visceral leishmaniasis to humans in the Gansu province, northwest China. To be able to control zoonotic transmission of the parasite to humans, a non-invasive loop-mediated isothermal amplification (LAMP) assay to specifically detect L. infantum infections in dogs was developed. Methods: The primers used in the LAMP assay were designed to target kinetoplast DNA minicircle sequences of the L. infantum isolate MCAN/CN/90/SC and tested using DNA isolated from promastigotes of different Leishmania species. The LAMP assay was evaluated with conjunctional swab samples obtained from 111 and 33 dogs living in an endemic and a non-endemic region of zoonotic visceral leishmaniasis in the Gansu province, respectively. The LAMP assay was also compared with conventional PCR, ELISA and microscopy using conjunctional swab, serum and bone marrow samples from the dogs, respectively. Results: The LAMP assay detected 1 fg of L. infantum DNA purified from cultured promastigotes which was 10-fold more sensitive than a conventional PCR test using Leishmania genus-specific primers. No cross reaction was observed with DNA isolated from promastigotes of L. donovani, L. major, L. tropica, and L. braziliensis, and the L. infantum reference strain MHOM/TN/80/IPT1. The L. infantum-positive rates obtained for field-collected samples were 61.3%, 58.6%, 40.5% and 10.8% by LAMP, PCR, ELISA and microscopy, respectively. As only one out of the 33 samples from control dogs from the non-endemic region of zoonotic visceral leishmaniasis was positive by the LAMP assay and the PCR test, the observed true negative rate (specificity) was 97% for both methods. Conclusion: This study has shown that the non-invasive, conjunctional swab-based LAMP assay developed was more sensitive in the detection of leishmaniasis in dogs than PCR, ELISA and microscopy. The findings indicate that the LAMP assay is a sensitive and specific method for the field surveillance of domestic dogs, particularly of asymptomatic canines, in ZVL-endemic areas in western China

    Study on inform ation service system for ocean d isa ster preven tion and reduction in Ta iwan Stra it ar ea

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    [摘要]:台湾海峡及其周边海域是我国海洋灾害发生的重点区域, 充分利用我国在该区域投入巨资 构建的海洋动力环境实时立体监测系统所获取的海洋动力参数数据, 构建区域性防灾减灾信息服务 系统具有重要的意义。从台湾海峡海洋动力环境立体监测数据防灾减灾应用和网络服务角度出发, 提出了防灾减灾信息服务的数据服务、信息服务和决策服务等3个层次的划分方法, 研究了基于数 据仓库、XML、中间件和基于地球球体模型的三维可视化等的服务技术实现策略。提出的防灾减灾 信息服务系统构建技术充分考虑了不同用户的应用需求, 并通过工程化实践提升了我国海洋动力环 境立体监测信息的广泛共享和深度应用的层次。[Abstract]:Taiwan Stra it and its c ircumjacent ocean region are main region of ocean disaster occurrence in Ch ina, so substantive fund has been devoted to construct ocean ic dynamic environment stereo rea l2timemon itoring system. Then the construction of information service system for oceanic d isaster prevention and reduction is of great impor2 tance tomak ing the best of the acqu ired data. In this paper, the service content partitionwas put forward firstly ac2 cord ing to the requirement of the ocean disaster prevention and reduction, which includes three aspects, .i e. data service, information service and decision2making service. The service realization technologieswere studied, wh ich includes datawarehouse, XML, middle2ware and three2dimensional visualization based on earth spheremode.l The technology system presented in th is paper upgraded the ocean dynamic environment stereomon itoring data sharing and its app lication level in Ch ina through meeting the requ irement of users and engineer ing app lication practice.国家高新技术研究发展计划( 863 计划)项目资助( 2009AA12Z208

    Predicting residue-wise contact orders in proteins by support vector regression

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    BACKGROUND: The residue-wise contact order (RWCO) describes the sequence separations between the residues of interest and its contacting residues in a protein sequence. It is a new kind of one-dimensional protein structure that represents the extent of long-range contacts and is considered as a generalization of contact order. Together with secondary structure, accessible surface area, the B factor, and contact number, RWCO provides comprehensive and indispensable important information to reconstructing the protein three-dimensional structure from a set of one-dimensional structural properties. Accurately predicting RWCO values could have many important applications in protein three-dimensional structure prediction and protein folding rate prediction, and give deep insights into protein sequence-structure relationships. RESULTS: We developed a novel approach to predict residue-wise contact order values in proteins based on support vector regression (SVR), starting from primary amino acid sequences. We explored seven different sequence encoding schemes to examine their effects on the prediction performance, including local sequence in the form of PSI-BLAST profiles, local sequence plus amino acid composition, local sequence plus molecular weight, local sequence plus secondary structure predicted by PSIPRED, local sequence plus molecular weight and amino acid composition, local sequence plus molecular weight and predicted secondary structure, and local sequence plus molecular weight, amino acid composition and predicted secondary structure. When using local sequences with multiple sequence alignments in the form of PSI-BLAST profiles, we could predict the RWCO distribution with a Pearson correlation coefficient (CC) between the predicted and observed RWCO values of 0.55, and root mean square error (RMSE) of 0.82, based on a well-defined dataset with 680 protein sequences. Moreover, by incorporating global features such as molecular weight and amino acid composition we could further improve the prediction performance with the CC to 0.57 and an RMSE of 0.79. In addition, combining the predicted secondary structure by PSIPRED was found to significantly improve the prediction performance and could yield the best prediction accuracy with a CC of 0.60 and RMSE of 0.78, which provided at least comparable performance compared with the other existing methods. CONCLUSION: The SVR method shows a prediction performance competitive with or at least comparable to the previously developed linear regression-based methods for predicting RWCO values. In contrast to support vector classification (SVC), SVR is very good at estimating the raw value profiles of the samples. The successful application of the SVR approach in this study reinforces the fact that support vector regression is a powerful tool in extracting the protein sequence-structure relationship and in estimating the protein structural profiles from amino acid sequences

    S9, a Novel Anticancer Agent, Exerts Its Anti-Proliferative Activity by Interfering with Both PI3K-Akt-mTOR Signaling and Microtubule Cytoskeleton

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    BACKGROUND: Deregulation of the phosphatidylinositol 3-kinases (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway plays a central role in tumor formation and progression, providing validated targets for cancer therapy. S9, a hybrid of alpha-methylene-gamma-lactone and 2-phenyl indole compound, possessed potent activity against this pathway. METHODOLOGY/PRINCIPAL FINDINGS: Effects of S9 on PI3K-Akt-mTOR pathway were determined by Western blot, immunofluorescence staining and in vitro kinas assay. The interactions between tubulin and S9 were investigated by polymerization assay, CD, and SPR assay. The potential binding modes between S9 and PI3K, mTOR or tubulin were analyzed by molecular modeling. Anti-tumor activity of S9 was evaluated in tumor cells and in nude mice bearing human cancer xenografts. S9 abrogated EGF-activated PI3K-Akt-mTOR signaling cascade and Akt translocation to cellular membrane in human tumor cells. S9 possessed inhibitory activity against both PI3K and mTOR with little effect on other tested 30 kinases. S9 also completely impeded hyper-phosphorylation of Akt as a feedback of inhibition of mTOR by rapamycin. S9 unexpectedly arrested cells in M phase other than G1 phase, which was distinct from compounds targeting PI3K-Akt-mTOR pathway. Further study revealed that S9 inhibited tubulin polymerization via binding to colchicine-binding site of tubulin and resulted in microtubule disturbance. Molecular modeling indicated that S9 could potentially bind to the kinase domains of PI3K p110alpha subunit and mTOR, and shared similar hydrophobic interactions with colchicines in the complex with tubulin. Moreover, S9 induced rapid apoptosis in tumor cell, which might reflect a synergistic cooperation between blockade of both PI3-Akt-mTOR signaling and tubulin cytoskeleton. Finally, S9 displayed potent antiproliferative activity in a panel of tumor cells originated from different tissue types including drug-resistant cells and in nude mice bearing human tumor xenografts. CONCLUSIONS/SIGNIFICANCE: Taken together, S9 targets both PI3K-Akt-mTOR signaling and microtubule cytoskeleton, which combinatorially contributes its antitumor activity and provides new clues for anticancer drug design and development

    The Association between OGG1 Ser326Cys Polymorphism and Lung Cancer Susceptibility: A Meta-Analysis of 27 Studies

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    Background: Numerous studies have investigated association of OGG1 Ser326Cys polymorphism with lung cancer susceptibility; however, the findings are inconsistent. Therefore, we performed a meta-analysis based on 27 publications encompass 9663 cases and 11348 controls to comprehensively evaluate such associations. Methods: We searched publications from MEDLINE and EMBASE which were assessing the associations between OGG1 Ser326Cys polymorphism and lung cancer risk. We calculated pooled odds ratio (OR) and 95 % confidence interval (CI) by using either fixed-effects or random-effects model. We used genotype based mRNA expression data from HapMap for SNP rs1052133 in normal cell lines among 270 subjects with four different ethnicities. Results: The results showed that individuals carrying the Cys/Cys genotype did not have significantly increased risk for lung cancer (OR = 1.15, 95 % CI = 0.98–1.36) when compared with the Ser/Ser genotype; similarly, no significant association was found in recessive, dominant or heterozygous co-dominant model (Ser/Cys vs. Cys/Cys). However, markedly increased risks were found in relatively large sample size (Ser/Ser vs. Cys/Cys: OR = 1.29, 95 % CI = 1.13–1.48, and recessive model: OR = 1.19, 95 % CI = 1.07–1.32). As to histological types, we found the Cys/Cys was associated with adenocarcinoma risk (Ser/Ser vs. Cys/Cys: OR = 1.32, 95 % CI = 1.12–1.56; Ser/Cys vs. Cys/Cys: OR = 1.19, 95 % CI = 1.04–1.37, and recessive model OR = 1.23, 95 % CI = 1.08–1.40). No significant difference of OGG1 mRNA expression was found among genotypes between differen
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