RÉACTION DE PRODUCTION DE PIONS PRÈS DU SEUIL

La distribution angulaire de la section efficace différentielle de la réaction 40Ca(p, π+)41Ca (état fondamental) a été mesurée. L'étude de la dépendance en énergie de la production de pions près du seuil a été faite à transfert de moment constant. La section efficace décroît d'un facteur 7 pour des énergies de protons variant de 154 à 149 MeV (Eπ varie de 17,4 à 12,4 MeV). L'interprétation des résultats est faite dans le cadre d'un mécanisme à un nucléon

Dipole-Quadrupole Theory of Surface Enhanced Infrared Absorption and Appearance of Forbidden Lines in the SEIRA Spectra of Symmetrical Molecules

The paper presents main aspects of the Dipole-Quadrupole theory of Surface Enhanced Infrared Absorption (SEIRA). It is pointed out the possibility of appearance of the lines, caused by totally symmetric vibrations transforming after the unit irreducible representation, which are forbidden in usual infrared absorption spectra in molecules with sufficiently high symmetry. Observation of such lines in the SEIRA spectra of diprotonated and ethylene, adsorbed on and on mordenites is pointed out. The results well agree with our ideas about surface enhanced optical processes, based on the conception of a strong quadrupole light-molecule interaction, which allows us to develop the SERS and SEHRS theories.Comment: 15 pages,3 figures, 1 tabl

Dust in the Ionized Medium of the Galaxy: GHRS Measurements of Al III and S III

We present interstellar absorption line measurements of the ions S III and Al III towards six stars using archival Goddard High Resolution Spectrograph data. The ions Al III and S III trace heavily depleted and non-depleted elements, respectively, in ionized gas. We use the photoionization code CLOUDY to derive the ionization correction relating N(Al III)/N(S III) to the gas-phase abundance [Al/S]_i in the ionized gas. For spectral types considered here, the corrections are small and independent of the assumed ionization parameter. Using the results of these photoionization models, we find [Al/S]_i = -1.0 in the ionized gas towards three disk stars. These values of [Al/S]_i (=[Al/H]_i) imply that Al-bearing grains are present in the ionized nebulae around these stars. If the WIM of the Galaxy is photoionized by OB stars, our data for two halo stars imply [Al/S]_i = -0.4 to -0.5 in the WIM and thus the presence of dust grains containing Al in this important phase of the ISM. While photoionization appears to be the most likely origin of the ionization for Al III and S III, we cannot rule out confusion from the presence of hot, collisionally ionized gas along two sightlines. We find that [Al/S]_i in the ionized gas along the six sightlines is anti-correlated with the electron density and average sightline neutral density. The degree of grain destruction in the ionized medium of the Galaxy is not much higher than in the warm neutral medium. The existence of grains in the ionized regions studied here has important implications for the thermal balance of these regions. (Abstract Abridged)Comment: 30 pages including 8 embedded tables and 8 embedded figures. Accepted for publication in the Astrophysical Journa

Pure-radiation gravitational fields with a simple twist and a Killing vector

Pure-radiation solutions are found, exploiting the analogy with the Euler- Darboux equation for aligned colliding plane waves and the Euler-Tricomi equation in hydrodynamics of two-dimensional flow. They do not depend on one of the spacelike coordinates and comprise the Hauser solution as a special subcase.Comment: revtex, 9 page

Rapid diagnostic tests for molecular surveillance of Plasmodium falciparum malaria -assessment of DNA extraction methods and field applicability

Background: The need for new malaria surveillance tools and strategies is critical, given improved global malaria control and regional elimination efforts. High quality Plasmodium falciparum DNA can reliably be extracted from malaria rapid diagnostic tests (RDTs). Together with highly sensitive molecular assays, wide scale collection of used RDTs may serve as a modern tool for improved malaria case detection and drug resistance surveillance. However, comparative studies of DNA extraction efficiency from RDTs and the field applicability are lacking. The aim of this study was to compare and evaluate different methods of DNA extraction from RDTs and to test the field applicability for the purpose of molecular epidemiological investigations. Methods: DNA was extracted from two RDT devices (Paracheck-PfW and SD Bioline Malaria Pf/Pan (R)), seeded in vitro with 10-fold dilutions of cultured 3D7 P. falciparum parasites diluted in malaria negative whole blood. The level of P. falciparum detection was determined for each extraction method and RDT device with multiple nested-PCR and real-time PCR assays. The field applicability was tested on 855 paired RDT (Paracheck-Pf) and filter paper (Whatman (R) 3MM) blood samples (734 RDT negative and 121 RDT positive samples) collected from febrile patients in Zanzibar 2010. RDT positive samples were genotyped at four key single nucleotide polymorphisms (SNPs) in pfmdr1 and pfcrt as well as for pfmdr1 copy number, all associated with anti-malarial drug resistance. Results: The P. falciparum DNA detection limit varied with RDT device and extraction method. Chelex-100 extraction performed best for all extraction matrixes. There was no statistically significant difference in PCR detection rates in DNA extracted from RDTs and filter paper field samples. Similarly there were no significant differences in the PCR success rates and genotyping outcomes for the respective SNPs in the 121 RDT positive samples. Conclusions: The results support RDTs as a valuable source of parasite DNA and provide evidence for RDT-DNA extraction for improved malaria case detection, molecular drug resistance surveillance, and RDT quality control.ACT Consortium through Bill and Melinda Gates Foundation; Swedish International Development Agency (SIDA) [SWE 2009-193]; Swedish Civil Contingencies Agency (MSB) [2010-7991]; Swedish Medical Research Council (VR) [2009-3785]; Goljes Foundationinfo:eu-repo/semantics/publishedVersio