Nature of Sonoluminescence: Noble Gas Radiation Excited by Hot Electrons in "Cold" Water

We show that strong electric fields occurring in water near the surface of collapsing gas bubbles because of the flexoelectric effect can provoke dynamic electric breakdown in a micron-size region near the bubble and consider the scenario of the SBSL. The scenario is: (i) at the last stage of incomplete collapse of the bubble the gradient of pressure in water near the bubble surface has such a value and sign that the electric field arising from the flexoelectric effect exceeds the threshold field of the dynamic electrical breakdown of water and is directed to the bubble center; (ii) mobile electrons are generated because of thermal ionization of water molecules near the bubble surface; (iii) these electrons are accelerated in ''cold'' water by the strong electric fields; (iv) these hot electrons transfer noble gas atoms dissolved in water to high-energy excited states and optical transitions between these states produce SBSL UV flashes in the trasparency window of water; (v) the breakdown can be repeated several times and the power and duration of the UV flash are determined by the multiplicity of the breakdowns. The SBSL spectrum is found to resemble a black-body spectrum where temperature is given by the effective temperature of the hot electrons. The pulse energy and some other characteristics of the SBSL are found to be in agreement with the experimental data when realistic estimations are made.Comment: 11 pages (RevTex), 1 figure (.ps

LLT Location Learning Test [herz. ed.; Nederlandse bewerking]

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LLT Location Learning Test [revised ed.; English version]

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LASER TECHNIQUES FOR SPECTROSCOPY OF CORE-EXCITED ATOMIC LEVELS

Nous exposons trois techniques permettant l'utilisation de lasers accordables pour la spectroscopie à haute résolution et pour la spectroscopie picoseconde d'états atomiques excités en couches internes. Ce sont la spectroscopie d'absorption anti-Stokes, l'émission laser induite à partir d'états métastables et l'excitation laser sélective d'états excités en couches internes.We discuss three thechniques which allow the use of tunable lasers for high resolution and picosecond time scale spectroscopy of core-excited atomic levels. These aren : anti-Stokes absorption spectroscopy, laser induced emission from metastable levels, and laser designation of selected core-excited levels

Treatment for Fisher syndrome, Bickerstaff's brainstem encephalitis and related disorders

Fisher syndrome is one of the regional variants of Guillain-Barré syndrome, characterised by impairment of eye movements (ophthalmoplegia), incoordination (ataxia) and loss of tendon reflexes (areflexia). It can occur in more limited forms, and may overlap with Guillain-Barré syndrome. A further variant is associated with upper motor neuron signs and disturbance of consciousness (Bickerstaff's brainstem encephalitis). All of these variants are associated with anti-GQ1b IgG antibodies. Intravenous immunoglobulin (IVIg) and plasma exchange are often used as treatments in this patient group. This review was undertaken to systematically assess any available randomised controlled data on acute immunomodulatory therapies in Fisher Syndrome or its variants