664 research outputs found
A new method of observing weak extended x-ray sources with RHESSI
We present a new method, fan-beam modulation, for observing weak extended
x-ray sources with the Reuven Ramaty High-Energy Solar Spectroscopic Imager
(RHESSI). This space-based solar x-ray and gamma-ray telescope has much greater
sensitivity than previous experiments in the 3-25 keV range, but is normally
not well suited to detecting extended sources since their signal is not
modulated by RHESSI's rotating grids. When the spacecraft is offpointed from
the target source, however, the fan-beam modulation time-modulates the
transmission by shadowing resulting from exploiting the finite thickness of the
grids. In this paper we detail how the technique is implemented and verify its
consistency with sources with clear known signals that have occurred during
RHESSI offpointing: microflares and the Crab Nebula. In both cases the results
are consistent with previous and complementary measurements. Preliminary work
indicates that this new technique allows RHESSI to observe the integrated hard
x-ray spectrum of weak extended sources on the quiet Sun.Comment: Publishe
Role of Epigenetic Modification and Immunomodulation in a Murine Prostate Cancer Model
INTRODUCTION. Decreased expression of highly immunogenic cancer-testis antigens (CTA) might help tumor to achieve low immunogenicity, escape immune surveillance and grow unimpeded. Our aim was to evaluate CTA expression in tumor and normal tissues and to investigate possible means of improving the immune response in a murine prostate cancer (CaP) model by using the combination of epigenetic modifier 5-azacitidine (5-AzaC) and immunomodulator lenalidomide. No study to date has examined the effect of this combination on the prostate cancer or its impact on antigen-presenting cells (APC). MATERIALS AND METHODS. Gene microarrays were performed to compare expression of several CTA in murine prostate cancer (RM-1 cells) and normal prostate. RM-1 cells were treated with 5-AzaC and real-time PCR was performed to investigate the expression of several CTA. Western blotting was used to determine whether expression of CTA-specific mRNA induced by 5-AzaC resulted in increase in the corresponding protein. Effect of the epigenetic agents and immunomodulators was assessed on dendritic cells (DC) using flow cytometry, ELISA and T-cell proliferation assay. RESULTS. Gene arrays demonstrated decreased expression of 35 CTA in CaP tissue compared to normal prostate. 5-AzaC treatment of RM-1 prostate cancer cells upregulated the expression of all 13 CTA tested in a dose-dependent fashion. DC were treated with 5-AzaC and lenalidomide and the expression of surface markers MHC Class I, MHC Class II, CD80, CD86, CD 205, and CD40 was increased. Combination of 5-AzaC and lenalidomide enhances the ability of DC to stimulate T-cell proliferation in mixed leukocyte reaction. Secretion of IL-12 and IL-15 by DC increased significantly with addition of 5-AzaC or 5-AzaC and lenalidomide. CONCLUSIONS. Decreased expression of CTA by prostate cancer may be a means of escaping immune monitoring. Combination of epigenetic modifications and immunomodulation by 5-AzaC and lenalidomide increased tumor immunogenicity and enhanced DC function and may be used in the treatment of advanced prostate cancer
Quantum Games with Correlated Noise
We analyze quantum game with correlated noise through generalized
quantization scheme. Four different combinations on the basis of entanglement
of initial quantum state and the measurement basis are analyzed. It is shown
that the advantage that a quantum player can get by exploiting quantum
strategies is only valid when both the initial quantum state and the
measurement basis are in entangled form. Furthermore, it is shown that for
maximum correlation the effects of decoherence diminish and it behaves as a
noiseless game.Comment: 12 page
Catalytic Hydrolysis of Ethyl Acetate using Cation Exchange Resin (Amberlyst - 15) : A Kinetic Study
NASSAM: a server to search for and annotate tertiary interactions and motifs in three-dimensional structures of complex RNA molecules
Similarities in the 3D patterns of RNA base interactions or arrangements can provide insights into their functions and roles in stabilization of the RNA 3D structure. Nucleic Acids Search for Substructures and Motifs (NASSAM) is a graph theoretical program that can search for 3D patterns of base arrangements by representing the bases as pseudo-atoms. The geometric relationship of the pseudo-atoms to each other as a pattern can be represented as a labeled graph where the pseudo-atoms are the graph's nodes while the edges are the inter-pseudo-atomic distances. The input files for NASSAM are PDB formatted 3D coordinates. This web server can be used to identify matches of base arrangement patterns in a query structure to annotated patterns that have been reported in the literature or that have possible functional and structural stabilization implications. The NASSAM program is freely accessible without any login requirement at http://mfrlab.org/grafss/nassam/
Competitive stochastic noises in coherently driven two-level atoms and quantum interference
A system of coherently-driven two-level atoms is analyzed in presence of two
independent stochastic perturbations: one due to collisions and a second one
due to phase fluctuations of the driving field. The behaviour of the quantum
interference induced by the collisional noise is considered in detail. The
quantum-trajectory method is utilized to reveal the phase correlations between
the dressed states involved in the interfering transition channels. It is shown
that the quantum interference induced by the collisional noise is remarkably
robust against phase noise. This effect is due to the fact that the phase
noise, similarly to collisions, stabilizes the phase-difference between the
dressed states.Comment: accepted for publication in J. Opt.
Evaluation of bio-crude refinery value chains:experimental fractional distillation, supercritical CO2 extraction, and hydrotreatment
Rigorous Multicomponent Reactive Separations Modelling : Complete Consideration of Reaction-Diffusion Phenomena
This paper gives the first step of the development of a rigorous multicomponent reactive separation model. Such a model is highly essential to further the optimization of acid gases removal plants (CO2 capture, gas treating, etc.) in terms of size and energy consumption, since chemical solvents are conventionally used.Firstly, two main modelling approaches are presented: the equilibrium-based and the rate-based approaches. Secondly, an extended rate-based model with rigorous modelling methodology for diffusion-reaction phenomena is proposed. The film theory and the generalized Maxwell-Stefan equations are used in order to characterize multicomponent interactions. The complete chain of chemical reactions is taken into account. The reactions can be kinetically controlled or at chemical equilibrium, and they are considered for both liquid film and liquid bulk. Thirdly, the method of numerical resolution is described. Coupling the generalized Maxwell-Stefan equations with chemical equilibrium equations leads to a highly non-linear Differential-Algebraic Equations system known as DAE index 3. The set of equations is discretized with finite-differences as its integration by Gear method is complex. The resulting algebraic system is resolved by the Newton- Raphson method. Finally, the present model and the associated methods of numerical resolution are validated for the example of esterification of methanol. This archetype non-electrolytic system permits an interesting analysis of reaction impact on mass transfer, especially near the phase interface. The numerical resolution of the model by Newton-Raphson method gives good results in terms of calculation time and convergence. The simulations show that the impact of reactions at chemical equilibrium and that of kinetically controlled reactions with high kinetics on mass transfer is relatively similar. Moreover, the Fickâs law is less adapted for multicomponent mixtures where some abnormalities such as counter-diffusion take place
Quantum trajectory approach to stochastically-induced quantum interference effects in coherently-driven two-level atoms
Stochastic perturbation of two-level atoms strongly driven by a coherent
light field is analyzed by the quantum trajectory method. A new method is
developed for calculating the resonance fluorescence spectra from numerical
simulations. It is shown that in the case of dominant incoherent perturbation,
the stochastic noise can unexpectedly create phase correlation between the
neighboring atomic dressed states. This phase correlation is responsible for
quantum interference between the related transitions resulting in anomalous
modifications of the resonance fluorescence spectra.Comment: paper accepted for publicatio
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