942 research outputs found

    TURBULENT STRESS DISTRIBUTION IN THE TURBULENT BOUNDARY LAYER ON A PERMEABLE POROUS PLATE

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    In this paper the results of experimental tests on turbulent boundary layer on a plate with air blowing through permeable porous wall are presented. Tests were performed in an aerodynamic tunnel varying the blowing rate within the range of 0 to 2.5% of the air flow velocity in the tunnel, using thermoanemometers of constant temperature. It has been determined that the blowing increases the boundary layer thickness and strongly transforms the boundary layer inner part and turbulent nucleus, while the outer part remains not deformed. An increase in blowing causes an abrupt viscous stress decrease, also decreasing skin friction. Thick boundary layers (up to 120 mm) allowed a profound analysis of Reynolds' turbulent stresses. It has been found a general distribution of turbulent stress in the turbulent layer which is independent of blowing velocity. It has been established for the turbulent characteristics that the determining coordinate is the relative horizontal velocity, not the distance from the wall. With a turbulent stress database obtained from turbulent stresses direct measurements, it has been proposed a flow model for boundary layer on a permeable porous plate. It has also been demonstrated that in high blowing conditions the horizontal velocity profile in the boundary layer becomes equal to the velocity profile in a plane jet

    Performance Studies of Prototype II for the CASTOR forward Calorimeter at the CMS Experiment

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    We present results of the performance of the second prototype of the CASTOR quartz-tungsten sampling calorimeter, to be installed in the very forward region of the CMS experiment at the LHC. The energy linearity and resolution, as well as the spatial resolution of the prototype to electromagnetic and hadronic showers are studied with E=20-200 GeV electrons, E=20-350 GeV pions, and E=50,150 GeV muons from beam tests carried out at CERN/SPS in 2004. The responses of the calorimeter using two different types of photodetectors (avalanche photodiodes APDs, and photomultiplier tubes PMTs) are compared.Comment: 16 pages, 22 figs., submitted to EPJ-

    Evidence and ideology as a rationale for light-therapy in Russia: from the Soviet Union to the present day.

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    Light therapy is still used to treat a number of common diseases in Russia. The practice is firmly anchored in history: Soviet clinical practice was divorced from the emerging field of evidence-based medicine. Medical researchers were cut off from international medical research and scientific literature, with much Soviet scientific activity based on a particular socialist ideology. In this study, the use of light therapy serves as a case study to explore tensions between international evidence-based medicine and practices developed in isolation under the Soviet Union, the legacy of which is to the detriment of many patients today. We used four different search methods to uncover scientific and grey literature, both historical and contemporary. We assessed the changing frequency of publications over time and contrasted the volume of literature on light therapy with more orthodox treatments such as statins and painkillers. Our search found an increasing number and comparatively large body of scientific publications on light therapy in the Russian language, and many publications emanating from prestigious Russian institutions. Combined with our analysis of the historical literature and our appraisal of 22 full text articles, this leads us to suggest that light therapy entered mainstream Soviet medical practice before the Stalinist period and still occupies an important position in contemporary Russian clinical practice. We propose that this outdated treatment survives in Russia in part due to the political, economic and social forces that helped to popularize it during Soviet times, and by the seeming justification offered by poorly executed studies

    On the folding and deployment of tape springs: a large displacements and large rotations rod model with highly flexible thin-walled cross-section

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    International audienceIn the framework of deployable structures, we focus on the modeling of tape springs, i.e. rod-like elastic bodies with thin-walled cross-section which develop localized folds due to a flattening of the cross-section. A rod model with highly deformable cross-section and few kinematics parameters is derived from a complete shell model, for large displacements, large rotations and dynamics. The simplicity of the model is achieved by introducing an elastica kinematics to describe the changes in the cross-section shape. This model is able to handle the formation of localized folds which can move along the rod line, merge or split, allowing to simulate complex scenarios of folding and deployment

    Circulating microRNAs in lung cancer: prospects for diagnosis, prognosis, and prediction of antitumor treatment efficacy

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    The review considers the main techniques to extract microRNA (miRNA) from various biological fluids (in particular, the serum and plasma), approaches to the analysis of miRNA concentration and composition, and methods to normalize the results in data analyses. Advantages and drawbacks of the methods are described. Special attention is given to circulating miRNAs, which can be used as markers for minimally invasive diagnosis, prediction of antitumor treatment efficacy, and disease prognosis in lung cancer. The review discusses the prospects and limitations that arise as the clinical significance is evaluated for miRNAs as potential tumor markers and a better understanding is gained for the roles various miRNAs play in the pathogenesis of lung cancer

    Dynamics of LINE-1 retrotransposon methylation levels in circulating DNA from lung cancer patients undergoing antitumor therapy

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    Malignant cell transformation is accompanied with abnormal DNA methylation, such as the hypermethylation of certain gene promoters and hypomethylation of retrotransposons. In particular, the hypomethylation of the human-specific family of LINE-1 retrotransposons was observed in lung cancer tissues. It is also known that the circulating DNA (cirDNA) of blood plasma and cell-surface-bound circulating DNA (csb-cirDNA) of cancer patients accumulate tumor-specific aberrantly methylated DNA fragments, which are currently considered to be valuable cancer markers. This work compares LINE-1 retrotransposon methylation patterns in cirDNA of 16 lung cancer patients before and after treatment. CirDNA was isolated from blood plasma, and csb-cirDNA fractions were obtained by successive elution with EDTA-containing phosphate buffered saline and trypsin. Concentrations of methylated LINE-1 region 1 copies (LINE-1-met) were assayed by real-time methylation-specific PCR. LINE-1 methylation levels were normalized to the concentration of LINE-1 region 2, which was independent of the methylation status (LINE-1-Ind). The concentrations of LINE-1-met and LINE-1-Ind in csb-cirDNA of lung cancer patients exhibited correlations before treatment (r = 0.54), after chemotherapy (r = 0.72), and after surgery (r = 0.83) (P 0.05, respectively). These results suggest a need for the further investigation of dynamic changes in levels of LINE-1 methylation depending on the antitumor therapy

    Transverse Polarization of Σ+(1189)\Sigma^{+}(1189) in Photoproduction on a Hydrogen Target in CLAS

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    Experimental results on the Σ+(1189)\Sigma^+(1189) hyperon transverse polarization in photoproduction on a hydrogen target using the CLAS detector at Jefferson laboratory are presented. The Σ+(1189)\Sigma^+(1189) was reconstructed in the exclusive reaction γ+pKS0+Σ+(1189)\gamma+p\rightarrow K^{0}_{S} + \Sigma^+(1189) via the Σ+pπ0\Sigma^{+} \to p \pi^{0} decay mode. The KS0K^{0}_S was reconstructed in the invariant mass of two oppositely charged pions with the π0\pi^0 identified in the missing mass of the detected pπ+πp\pi^+\pi^- final state. Experimental data were collected in the photon energy range EγE_{\gamma} = 1.0-3.5 GeV (s\sqrt{s} range 1.66-2.73 GeV). We observe a large negative polarization of up to 95%. As the mechanism of transverse polarization of hyperons produced in unpolarized photoproduction experiments is still not well understood, these results will help to distinguish between different theoretical models on hyperon production and provide valuable information for the searches of missing baryon resonances.Comment: pages 1
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