178 research outputs found
Atomic Parity Violation : Principles, Recent Results, Present Motivations
We review the progress made in the determination of the weak charge, Q\_w, of
the cesium nucleus which raises the status of Atomic Parity Violation
measurements to that of a precision electroweak test. Not only is it necessary
to have a precision measurement of the electroweak asymmetry in the highly
forbidden 6S-7S transition, but one also needs a precise calibration procedure.
The 1999 precision measurement by the Boulder group implied a 2.5 sigma
deviation of Q\_w from the theoretical prediction. This triggered many particle
physicist suggestions as well as examination by atomic theoretical physicists
of several sources of corrections. After about three years the disagreement was
removed without appealing to "New Physics". Concurrently, an original
experimental approach was developed in our group for more than a decade. It is
based on detection by stimulated emission with amplification of the left- right
asymmetry. We present our decisive, recent progress together with our latest
results. We emphasize the important impact for electroweak theory, of future
measurements in cesium possibly pushed to the 0.1% level. Other possible
approaches are currently explored in several atoms
Review Paper: Myocardial Rupture After Acute Myocardial Infarction: A review
Myocardial rupture complications after acute myocardial infarction are infrequent but lethal. They mainly involve rupture of the ventricular free wall, ventricular septum, papillary muscle, or combined. We compare features of different kinds of myocardial ruptures after acute myocardial infarction by reviewing the clinical insights. Tanzania Medical Journal Vol. 23 (1) 2008: pp. 30-3
Laser desorption/laser ionization/time-of-flight mass spectrometer for the detection of polycyclic aromatic hydrocarbons desorbed from soot
Recent advances in the field of laser desorption/laser ionization mass spectrometry (LD/LI/MS) have renewed interest in these separation methods for fast analysis of chemical species adsorbed on soot particles. These techniques provide mass-separation of the desorbed phase with high selectivity and sensitivity and require very small amounts of soot to be collected. In particular the techniques provide a means to measure adsorbed polycyclic aromatic hydrocarbons (PAHs). PAHs are important precursors of carbonaceous soot particles, thus influence the quantity and morphology of particulate emission from various combustion processes. Furthermore, PAHs absorbed on the surface of the soot particles contribute to the carcinogenicity of the particles. Therefore, there is scientific interest in characterizing and quantifying these adsorbed PAHs in order to provide key information about the mechanism of the soot formation for various fuels and combustors and to understand their health impact. This has motivated various studies; however, an extensive characterization of the PAHs absorbed onto soot particles remains a challenge.NRC publication: Ye
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