853 research outputs found

    Biomedical journals and databases in Russia and Russian language in the former Soviet Union and beyond

    Get PDF
    In the 20th century, Russian biomedical science experienced a decline from the blossom of the early years to a drastic state. Through the first decades of the USSR, it was transformed to suit the ideological requirements of a totalitarian state and biased directives of communist leaders. Later, depressing economic conditions and isolation from the international research community further impeded its development. Contemporary Russia has inherited a system of medical education quite different from the west as well as counterproductive regulations for the allocation of research funding. The methodology of medical and epidemiological research in Russia is largely outdated. Epidemiology continues to focus on infectious disease and results of the best studies tend to be published in international periodicals. MEDLINE continues to be the best database to search for Russian biomedical publications, despite only a small proportion being indexed. The database of the Moscow Central Medical Library is the largest national database of medical periodicals, but does not provide abstracts and full subject heading codes, and it does not cover even the entire collection of the Library. New databases and catalogs (e.g. Panteleimon) that have appeared recently are incomplete and do not enable effective searching

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

    Get PDF
    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-

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

    Get PDF
    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

    Induced polarization of {\Lambda}(1116) in kaon electroproduction

    Full text link
    We have measured the induced polarization of the Λ(1116){\Lambda}(1116) in the reaction ep→eâ€ČK+Λep\rightarrow e'K^+{\Lambda}, detecting the scattered eâ€Če' and K+K^+ in the final state along with the proton from the decay Λ→pπ−\Lambda\rightarrow p\pi^-.The present study used the CEBAF Large Acceptance Spectrometer (CLAS), which allowed for a large kinematic acceptance in invariant energy WW (1.6≀W≀2.71.6\leq W \leq 2.7 GeV) and covered the full range of the kaon production angle at an average momentum transfer Q2=1.90Q^2=1.90 GeV2^2.In this experiment a 5.50 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. We have mapped out the WW and kaon production angle dependencies of the induced polarization and found striking differences from photoproduction data over most of the kinematic range studied. However, we also found that the induced polarization is essentially Q2Q^2 independent in our kinematic domain, suggesting that somewhere below the Q2Q^2 covered here there must be a strong Q2Q^2 dependence. Along with previously published photo- and electroproduction cross sections and polarization observables, these data are needed for the development of models, such as effective field theories, and as input to coupled-channel analyses that can provide evidence of previously unobserved ss-channel resonances.Comment: 13 figure

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

    Full text link
    Experimental results on the ÎŁ+(1189)\Sigma^+(1189) hyperon transverse polarization in photoproduction on a hydrogen target using the CLAS detector at Jefferson laboratory are presented. The ÎŁ+(1189)\Sigma^+(1189) was reconstructed in the exclusive reaction Îł+p→KS0+ÎŁ+(1189)\gamma+p\rightarrow K^{0}_{S} + \Sigma^+(1189) via the ÎŁ+→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+π−p\pi^+\pi^- final state. Experimental data were collected in the photon energy range EÎłE_{\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

    Measurement of Exclusive π0\pi^0 Electroproduction Structure Functions and their Relationship to Transversity GPDs

    Get PDF
    Exclusive π0\pi^0 electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in Q2Q^2, xBx_B, tt, and ϕπ\phi_\pi, in the Q2Q^2 range from 1.0 to 4.6 GeV2^2,\ −t-t up to 2 GeV2^2, and xBx_B from 0.1 to 0.58. Structure functions σT+ϔσL,σTT\sigma_T +\epsilon \sigma_L, \sigma_{TT} and σLT\sigma_{LT} were extracted as functions of tt for each of 17 combinations of Q2Q^2 and xBx_B. The data were compared directly with two handbag-based calculations including both longitudinal and transversity GPDs. Inclusion of only longitudinal GPDs very strongly underestimates σT+ϔσL\sigma_T +\epsilon \sigma_L and fails to account for σTT\sigma_{TT} and σLT\sigma_{LT}, while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity flip and helicity non-flip processes. The results confirm that exclusive π0\pi^0 electroproduction offers direct experimental access to the transversity GPDs.Comment: 6 pages, 2 figure

    Precision measurements of g1g_1 of the proton and the deuteron with 6 GeV electrons

    Full text link
    The inclusive polarized structure functions of the proton and deuteron, g1p and g1d, were measured with high statistical precision using polarized 6 GeV electrons incident on a polarized ammonia target in Hall B at Jefferson Laboratory. Electrons scattered at lab angles between 18 and 45 degrees were detected using the CEBAF Large Acceptance Spectrometer (CLAS). For the usual DIS kinematics, Q^2>1 GeV^2 and the final-state invariant mass W>2 GeV, the ratio of polarized to unpolarized structure functions g1/F1 is found to be nearly independent of Q^2 at fixed x. Significant resonant structure is apparent at values of W up to 2.3 GeV. In the framework of perturbative QCD, the high-W results can be used to better constrain the polarization of quarks and gluons in the nucleon, as well as high-twist contributions

    Cross sections for the γp→K*+Λ and γp→K*+Σ0 reactions measured at CLAS

    Get PDF
    The first high-statistics cross sections for the reactions γp→K*+Λ and γp→K*+Σ0 were measured using the CLAS detector at photon energies between threshold and 3.9 GeV at the Thomas Jefferson National Accelerator Facility. Differential cross sections are presented over the full range of the center-of-mass angles, and then fitted to Legendre polynomials to extract the total cross section. Results for the K*+Λ final state are compared with two different calculations in an isobar and a Regge model, respectively. Theoretical calculations significantly underestimate the K*+Λ total cross sections between 2.1 and 2.6 GeV, but are in better agreement with present data at higher photon energies
    • 

    corecore