192 research outputs found
Special behavior of alkali beam emission spectroscopy in low-ion-temperature plasma
Beam emission spectroscopy (BES) is a powerful plasma diagnostic method
especially suited for the measurement of plasma density and its fluctuations.
As such, synthetic BES codes are regularly used to aid the design or
utilization of these diagnostic systems. However, synthetic diagnostics can
also be used to study the method in previously not yet explored operational
conditions. This paper presents such an analysis utilizing the RENATE-OD
synthetic diagnostic code for a hypothetical alkali BES system on the HSX
stellarator. HSX is a device featuring an unusual operating regime in the world
of fusion devices due to the low ion temperature and low plasma density. It was
found that BES shows unusual tendencies in these conditions. The relation
between beam energy and plasma penetration in low-ion-temperature plasma,
together with unique emission features facilitated by low-density plasma, and
the underlying reasons behind these features are explored in this paper
The fickle Mutation of a Cytoplasmic Tyrosine Kinase Effects Sensitization but not Dishabituation in Drosophila Melanogaster
fickle is a P-element mutation identified from a screen for defects in courtship behavior and disrupts the fly homolog of Bruton's tyrosine kinase (Btk) gene (Baba et al., 1999). Here, we show that habituation of the olfactory jump reflex also is defective in fickle. Unlike, the prototypical memory mutants, rutabaga and dunce, which habituate more slowly than normal, fickle flies habituate faster than normal. fickle's faster-than-normal response decrement did not appear to be due to sensorimotor fatigue, and dishabituation of the jump response was normal. Based on a long-standing “two opponent process” theory of habituation, these data suggested that behavioral sensitization might be defective in fickle. To test this hypothesis, we designed a olfactory sensitization procedure, using the same stimuli to habituate (odor) and dishabituate (vortexing) flies. Mutant flies failed to show any sensitization with this procedure. Our study reveals a “genetic dissection” of sensitization and dishabituation and, for the first time, provides a biological confirmation of the two opponent process theory of habituation
Superdeformation in Po
The Yb(Si,5n) reaction at 148 MeV with thin targets was used
to populate high-angular momentum states in Po. Resulting rays
were observed with Gammasphere. A weakly-populated superdeformed band of 10
-ray transitions was found and has been assigned to Po. This is
the first observation of a SD band in the region in a nucleus
with . The of the new band is very similar to those of
the yrast SD bands in Hg and Pb. The intensity profile suggests
that this band is populated through states close to where the SD band crosses
the yrast line and the angular momentum at which the fission process dominates.Comment: 10 pages, revtex, 2 figs. available on request, submitted to Phys.
Rev. C. (Rapid Communications
Particle-hole excited states in 133 Te
Excited states in neutron-rich have been identified with the Gamma sphere array by measuring three- and higher-fold prompt coincidence events following spontaneous fission of Four types of particle-hole bands built on the known 334.3 keV isomer in are identified. The yrast and near yrast particle-hole states observed up to 6.2 MeV in have characteristics quite similar to those in These states are interpreted as a result of coupling a neutron \ensuremath{\nu}{h}_{11/2} hole to the core. The group of states observed above 5.214 MeV is the result of a neutron particle-hole excitation of the double magic core nucleus and is a candidate for a tilted rotor band. Shell-model calculations considering as a closed core have been performed and have provided guidance to the interpretation of the levels below 4.3 MeV. Very good agreement between theory and experiment is obtained for these states
Heat flow of the Earth and resonant capture of solar 57-Fe axions
In a very conservative approach, supposing that total heat flow of the Earth
is exclusively due to resonant capture inside the Earth of axions, emitted by
57-Fe nuclei on Sun, we obtain limit on mass of hadronic axion: m_a<1.8 keV.
Taking into account release of heat from decays of 40-K, 232-Th, 238-U inside
the Earth, this estimation could be improved to the value: m_a<1.6 keV. Both
the values are less restrictive than limits set in devoted experiments to
search for 57-Fe axions (m_a<216-745 eV), but are much better than limits
obtained in experiments with 83-Kr (m_a<5.5 keV) and 7-Li (m_a<13.9-32 keV).Comment: 8 page
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