2,801 research outputs found

    Coronary Artery Disease: from Atherosclerosis to Cardiogenic Shock

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    __Abstract__ The aim of this thesis is twofold: 1. to investigate the prognostic value of intracoronary imaging and blood biomarkers in patients with coronary artery di

    Approved CAR T cell therapies

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    Two autologous chimeric antigen receptor (CAR) T cell therapies (Kymriah™ and Yescarta™) were recently approved by the FDA. Kymriah™ is for the treatment of pediatric patients and young adults with refractory or relapse (R/R) B cell precursor acute ly

    Systematic study of Coulomb distortion effects in exclusive (e,e'p) reactions

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    A technique to deal with Coulomb electron distortions in the analysis of (e,e'p) reactions is presented. Thereby, no approximations are made. The suggested technique relies on a partial-wave expansion of the electron wave functions and a multipole decomposition of the electron and nuclear current in momentum space. In that way, we succeed in keeping the computational times within reasonable limits. This theoretical framework is used to calculate the quasielastic (e,e'p) reduced cross sections for proton knockout from the valence shells in 16^{16}O, 40^{40}Ca, 90^{90}Zr and 208^{208}Pb. The final-state interaction of the ejected proton with the residual nucleus is treated within an optical potential model. The role of electron distortion on the extracted spectroscopic factors is discussed.Comment: 45 pages, 10 encapsulated postscript figures, Revtex, uses epsfig.sty and fancybox.sty, to be published in Physical Review

    Magnetic Field induced Dimensional Crossover Phenomena in Cuprate Superconductors and their Implications

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    We discuss the occurrence of crossing points in the magnetization - temperature (m,T(m,T) plane within the framework of critical phenomena. It is shown that in a two-dimensional superconducting slab of thickness dsd_{s} mz(δ)m_{z}(\delta) versus temperature TT curves measured in different fields H=H(0,sin(δ),cos(δ))\mathbf{H} = H(0,\sin (\delta) ,\cos (\delta)) will cross at the critical temperature T_c of the slab. In contrast, in a 3D anisotropic bulk superconductor the crossing point occurs in the plot mz(δ)/Hz1/2m_{z}(\delta) /H_{z}^{1/2} versus TT. The experimental facts that 2D crossing point features have been observed in ceramics and in single crystals for H\mathbf{H} close to H=H(0,0,1)\mathbf{H} = H(0,0,1), but not for H=H(0,1,0)\mathbf{H} = H(0,1,0), is explained in terms of an angle-dependent crossover field separating the regions where 2D or 3D thermal fluctuations dominate. The measured 2D-crossing point data are used to estimate one of the fundamental parameters of cuprate superconductors, the minimum thickness of the slab (ds)(d_{s}), which remains superconducting. Our estimates, based on experimental 2D-crossing point data for single crystals, reveal that this length adopts material dependent values. Therefore, experimental data for T_c and λ2(T=0)\lambda_{\Vert}^{2}(T=0), plotted in terms of T_c versus 1/λ2(T=0)1/\lambda_{\Vert}^{2}(T=0) will not tend to a straight line with universal slope as the underdoped limit is approached. Implications for magnetic torque measurements are also worked out

    An explorative study of interface support for image searching

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    In this paper we study interfaces for image retrieval systems. Current image retrieval interfaces are limited to providing query facilities and result presentation. The user can inspect the results and possibly provide feedback on their relevance for the current query. Our approach, in contrast, encourages the user to group and organise their search results and thus provide more fine-grained feedback for the system. It combines the search and management process, which - according to our hypothesis - helps the user to onceptualise their search tasks and to overcome the query formulation problem. An evaluation, involving young design-professionals and di®erent types of information seeking scenarios, shows that the proposed approach succeeds in encouraging the user to conceptualise their tasks and that it leads to increased user satisfaction. However, it could not be shown to increase performance. We identify the problems in the current setup, which when eliminated should lead to more effective searching overall

    Meson exchange currents in electromagnetic one-nucleon emission

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    The role of meson exchange currents (MEC) in electron- and photon-induced one-nucleon emission processes is studied in a nonrelativistic model including correlations and final state interactions. The nuclear current is the sum of a one-body and of a two-body part. The two-body current includes pion seagull, pion-in-flight and the isobar current contributions. Numerical results are presented for the exclusive 16O(e,e'p)15N and 16O(\gamma,p)15N reactions. MEC effects are in general rather small in (e,e'p), while in (\gamma,p) they are always large and important to obtain a consistent description of (e,e'p) and (\gamma,p) data, with the same spectroscopic factors. The calculated (\gamma,p) cross sections are sensitive to short-range correlations at high values of the recoil momentum, where MEC effects are larger and overwhelm the contribution of correlations.Comment: 9 pages, 6 figure

    Relativistic analysis of the 208Pb(e,e'p)207Tl reaction at high momentum

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    The recent 208Pb(e,e'p)207Tl data from NIKHEF-K at high missing momentum (p_m>300 MeV/c) are compared to theoretical results obtained with a fully relativistic formalism previously applied to analyze data on the low missing momentum (p_m < 300 MeV/c) region. The same relativistic optical potential and mean field wave functions are used in the two p_m-regions. The spectroscopic factors of the various shells are extracted from the analysis of the low-p_m data and then used in the high-p_m region. In contrast to previous analyses using a nonrelativistic mean field formalism, we do not find a substantial deviation from the mean field predictions other than that of the spectroscopic factors, which appear to be consistent with both low- and high-p_m data. We find that the difference between results of relativistic and nonrelativistic formalisms is enhanced in the p_m<0 region that will be interesting to explore experimentally.Comment: 12 pages, LaTeX+Revtex, included 3 postscript figures. To appear in the Physical Review C (Rapid Communications

    Pressure dependence and mechanism of Mn promotion of silica-supported Co catalyst in the Fischer-Tropsch reaction

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    The mechanism of Mn promotion of a silica-supported Co catalyst in the Fischer-Tropsch reaction has been studied at varying pressures up to 20 bar. IR spectroscopy in combination with DFT calculations suggest adsorbed CO is activated by reaction with an oxygen vacancy in the MnO, which covers the Co surface. This leads to a higher activity, higher CHx coverage and thus higher C5+ and lower CH4 selectivity. Increasing the pressure magnifies the selectivity differences. However, above around 4 bar, the effect of Mn on the selectivities is reversed and the C5+ selectivity is decreased by Mn addition. This is tentatively attributed to Mn promoting the C-O bond dissociation but not the chain growth. Formed monomers have to migrate to stepped sites for chain growth on the Co surface. Whilst this is migration is not impeded by co-adsorbates at low pressure, migration could be hindered by especially the high CO coverage at high pressure

    Linear Field Dependence of the Normal-State In-Plane Magnetoresistance of Sr2RuO4

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    The transverse and longitudinal in-plane magnetoresistances in the normal state of superconducting Sr2RuO4 single crystals have been measured. At low temperatures, both of them were found to be positive with a linear magnetic-field dependence above a threshold field, a result not expected from electronic band theory. We argue that such behavior is a manifestation of a novel coherent state characterized by a spin pseudo gap in the quasi-particle excitation spectrum in Sr2RuO4.Comment: 4 pages + 5 figure
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