Angle resolved photoelectron spectroscopy of two-color XUV-NIR ionization with polarization control

Electron emission caused by extreme ultraviolet (XUV) radiation in the presence of a strong near infrared (NIR) field leads to multiphoton interactions that depend on several parameters. Here, a comprehensive study of the influence of the angle between the polarization directions of the NIR and XUV fields on the two-color angle-resolved photoelectron spectra of He and Ne is presented. The resulting photoelectron angular distribution strongly depends on the orientation of the NIR polarization plane with respect to that of the XUV field. The prevailing influence of the intense NIR field over the angular emission characteristics for He(1s) and Ne(2p) ionization lines is shown. The underlying processes are modeled in the frame of the strong field approximation (SFA) which shows very consistent agreement with the experiment reaffirming the power of the SFA for multicolor-multiphoton ionization in this regime

Non-Newtonian Couette-Poiseuille flow of a dilute gas

The steady state of a dilute gas enclosed between two infinite parallel plates in relative motion and under the action of a uniform body force parallel to the plates is considered. The Bhatnagar-Gross-Krook model kinetic equation is analytically solved for this Couette-Poiseuille flow to first order in the force and for arbitrary values of the Knudsen number associated with the shear rate. This allows us to investigate the influence of the external force on the non-Newtonian properties of the Couette flow. Moreover, the Couette-Poiseuille flow is analyzed when the shear-rate Knudsen number and the scaled force are of the same order and terms up to second order are retained. In this way, the transition from the bimodal temperature profile characteristic of the pure force-driven Poiseuille flow to the parabolic profile characteristic of the pure Couette flow through several intermediate stages in the Couette-Poiseuille flow are described. A critical comparison with the Navier-Stokes solution of the problem is carried out.Comment: 24 pages, 5 figures; v2: discussion on boundary conditions added; 10 additional references. Published in a special issue of the journal "Kinetic and Related Models" dedicated to the memory of Carlo Cercignan

Study of Antigenic properties of Human immunodeficiency Virus NEF protein Recombinant Analog

Protein p27/p25 is a product of HIV nef gene and is a multifunctional factor of HIV pathogenicity. Antigenic properties of recombinant NEF polypeptide which includes N-terminal fragment of HIV-1 p27 protein fused to E. coli ß-galactosidase were studied by serological and virological methods. The interaction was shown between recombinant NEF antigen and serums of HIV-positive individuals by ELISA, Western blot and line immunoassay. There was no interaction with sera of healthy individuals. The antigen specificity of recombinant antigen was shown in the reactions with commercial HIV-1 p27/p25 protein analog and with polyclonal antibodies to synthetic peptides corresponding to N-, C-terminal regions of HIV-1 p27/p25 protein. The interaction between IgG of rabbits immunized with recombinant NEF antigen and viral antigens was shown by indirect immunofluorescence and neutralizing assays. Thus it was proven the possibility of using recombinant NEF protein as an antigen for diagnostic and experimental purposes

Theoretical analysis and experimental applications of x-ray waveguides

This chapter presents a theoretical analysis of electromagnetic field propagation in planar waveguides and experimental results obtained with synchrotron and laboratory sources. The basic equations of electromagnetic modes in a front-coupling planar WG are presented in section 2, and section 3 reports a comparison between computer simulation and experimental results in the general case of tapered waveguides. Then an original algorithm to retrieve the amplitude and phase of the electromagnetic field at the exit of the planar WG using an iterative method is presented (section 4). A theoretical analysis and computer simulation for WG with an additional periodic structure on the side reflecting walls of the WG are described in section 5, and experimental results are discussed in chapter 6 proving that spatial resolutions of few hundred nanometres in phase contrast imaging can be obtained with a laboratory source. Conclusions are drawn in section 7