Radio and X-ray study of two multi-shell Supernova Remnants: Kes79 and G352.7-0.1

We investigate two multi-shell galactic supernova remnants (SNRs), Kes79 and G352.7-0.1, to understand the causes of such morphology. The research was carried out based on new and reprocessed archival VLA observations and XMM-Newton archival data. The surrounding was investigated based on data extracted from the HI Canadian Galactic Plane Survey, the 13^CO Galactic Ring Survey and the HI Southern Galactic Plane Survey. The present study revealed that the overall morphology of both SNRs is the result of the mass-loss history of their respective progenitor stars. Kes79 would be the product of the gravitational collapse of a massive O9 star evolving near a molecular cloud and within the precursor's wind-driven bubble, while G352.7-0.1 would be the result of interactions of the SNR with an asymmetric wind from the progenitor together with projection effects. No radio point source or pulsar wind nebula was found associated with the X-ray pulsar CXOU J185238.6+004020 in Kes79. The X-ray study of G352.7-0.1, on its hand, revealed that most of the thermal X-ray radiation completely fills in the interior of the remnant and originates in heated ejecta. Characteristic parameters, like radio flux, radio spectral index, age, distance, shock velocity, initial energy and luminosity, were estimated for both SNRs.Comment: 14 pages, 13 figures. Accepted to be published in Astronomy and Astrophysic

The most complete and detailed X-ray view of the SNR Puppis A

With the purpose of producing the first detailed full view of Puppis A in X-rays, we carried out new XMM-Newton observations covering the missing regions in the southern half of the supernova remnant (SNR) and combined them with existing XMM-Newton and Chandra data. The new images were produced in the 0.3-0.7, 0.7-1.0 and 1.0-8.0 energy bands. We investigated the SNR morphology in detail, carried out a multi-wavelength analysis and estimated the flux density and luminosity of the whole SNR. The complex structure observed across the remnant confirms that Puppis A evolves in an inhomogeneous, probably knotty interstellar medium. The southwestern corner includes filaments that perfectly correlate with radio features suggested to be associated with shock/cloud interaction. In the northern half of Puppis A the comparison with Spitzer infrared images shows an excellent correspondence between X-rays and 24 and 70 microns emission features, while to the south there are some matched and other unmatched features. X-ray flux densities of 12.6 X 10^-9, 6.2 X 10^-9, and 2.8 X 10^-9 erg cm^-2 s^-1 were derived for the 0.3-0.7, 0.7-1.0 and 1.0-8.0 keV bands, respectively. At the assumed distance of 2.2 kpc, the total X-ray luminosity between 0.3 and 8.0 keV is 1.2 X 10^37 erg s^-1. We also collected and updated the broad-band data of Puppis A between radio and GeV gamma-ray range, producing its spectral energy distribution. To provide constraints to the high-energy emission models, we re-analyzed radio data, estimating the energy content in accelerated particles to be Umin=4.8 X 10^49 erg and the magnetic field strength B=26 muG.Comment: Article accepted to be published in the Astronomy and Astrophysics Main Journa

Scattering Wave Functions at Bound State Poles

The normalisation relation between the bound and scattering S-state wave functions, extrapolated to the bound state pole, is derived from the Schroedinger equation. It is shown that, unlike previous work, the result does not depend on the details of the potential through the corresponding Jost function but is given uniquely in terms of the binding energy. The generalisations to higher partial waves and one-dimensional scattering are given.Comment: 15 pages Latex. No graph

An empirical mean-field model of symmetry-breaking in a turbulent wake

Improved turbulence modeling remains a major open problem in mathematical physics. Turbulence is notoriously challenging, in part due to its multiscale nature and the fact that large-scale coherent structures cannot be disentangled from small-scale fluctuations. This closure problem is emblematic of a greater challenge in complex systems, where coarse-graining and statistical mechanics descriptions break down. This work demonstrates an alternative data-driven modeling approach to learn nonlinear models of the coherent structures, approximating turbulent fluctuations as state-dependent stochastic forcing. We demonstrate this approach on a high-Reynolds number turbulent wake experiment, showing that our model reproduces empirical power spectra and probability distributions. The model is interpretable, providing insights into the physical mechanisms underlying the symmetry-breaking behavior in the wake. This work suggests a path toward low-dimensional models of globally unstable turbulent flows from experimental measurements, with broad implications for other multiscale systems

Thermal Ground Testing of Concorde and Veras or Improvement in French Test Methods and Facilities

The more numerous the requirements are in aerospace vehicle operations, the more the ground test facility have to improve both the nature and the quality of the equipment as well as the volume and the size of the sites, for the importance of ground testing cannot be over emphasized. As an example, two ground test programs are reviewed in this presentation, namely CONCORDE and VERAS. Special emphasis is given to the facility implementations due respectively to the static and fatigue test of CONCORDE in heat environment and to the dynamic test of VERAS in high level and transient temperature conditions

Comparison of bacterial communities of tilapia fish from Cameroon and Vietnam using PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis)

Fishes in general and tilapia in particular are traded all over the world. However, it is difficult to find out their exact geographical location. One of the techniques used in the traceability of fish and its byproductsconsist in analysing in a global way the whole viable and non viable bacterial communities. For this purpose, the molecular technique employing the bacterial 16S DNA banding profiles generated by PCR-DGGE (polymerase chain reaction-Denaturing gradient gel electrophoresis) was used to evaluate the differences between the bacterial profiles of fishes from Vietnam (An Giang, south province) and those of Cameroon (Yagoua, Maga, Lagdo). The different PCR-DGGE 16S rDNA banding profiles obtained were analysed and results showed that there were specific bands for each geographical location though some bands common to Cameroon and Vietnam were observed. Thismethod could be used as a rapid analytical traceability tool for fish products and could be considered as a provider of a unique biological bar code

Two-Pion Exchange in Proton-Proton Scattering

The contribution of the box and crossed two-pion-exchange diagrams to proton-proton scattering at 90$^{\circ}_{c.m.}$ is calculated in the laboratory momentum range up to 12 GeV/c. Relativistic form factors related to the nucleon and pion size and representing the pion source distribution based on the quark structure of the hadronic core are included at each vertex of the pion-nucleon interaction. These form factors depend on the four-momenta of the exchanged pions and scattering nucleons. Feynman-diagram amplitudes calculated without form factors are checked against those derived from dispersion relations. In this comparison, one notices that a very short-range part of the crossed diagram, neglected in dispersion-relation calculations of the two-pion-exchange nucleon-nucleon potential, gives a sizable contribution. In the Feynman-diagram calculation with form factors the agreement with measured spin-separated cross sections, as well as amplitudes in the lower part of the energy range considered, is much better for pion-nucleon pseudo-vector vis \`a vis pseudo-scalar coupling. While strengths of the box and crossed diagrams are comparable for laboratory momenta below 2 GeV/c, the crossed diagram dominates for larger momenta, largely due to the kinematics of the crossed diagram allowing a smaller momentum transfer in the nucleon center of mass. An important contribution arises from the principal-value part of the integrals which is non-zero when form factors are included. It seems that the importance of the exchange of color singlets may extend higher in energy than expected

Induced pseudoscalar form factor of the nucleon at two-loop order in chiral perturbation theory

We calculate the imaginary part of the induced pseudoscalar form factor of the nucleon $G_P(t)$ in the framework of two-loop heavy baryon chiral perturbation theory. The effect of the calculated three-pion continuum on the pseudoscalar constant $g_P = (m_\mu/2M) G_P(t=-0.877m_\mu^2)$ measurable in ordinary muon capture $\mu^-p\to \nu_\mu n$ turns out to be negligibly small. Possible contributions from counterterms at two-loop order are numerically smaller than the uncertainty of the dominant pion-pole term proportional to the pion-nucleon coupling constant $g_{\pi N}= 13.2\pm 0.2$. We conclude that a sufficiently accurate representation of the induced pseudoscalar form factor of the nucleon at low momentum transfers $t$ is given by the sum of the pion-pole term and the Adler-Dothan-Wolfenstein term: $G_P(t) = 4g_{\pi N} M f_\pi/ (m_\pi^2 -t)- 2g_A M^2 /3$, with $= (0.44 \pm 0.02)$ fm$^2$ the axial mean square radius of the nucleon.Comment: 6 pages, 2 figures, accepted for publication in Physical Review

In vitro reversion of amphotericin B resistance in Leishmania donovani by poloxamer 188

A micellar formulation of amphotericin B (AmB) solubilized with poloxamer 188 was evaluated against an AmB Leishmania donovani-resistant line. A concave isobologram showed a synergistic effect of this association against promastigotes. This result was confirmed with amastigotes since the 50% effective concentration of the new formulation was 100 times less than that of the control AmB formulation