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Collective excitations in quantum Hall liquid crystals: Single-mode approximation calculations
A variety of recent experiments probing the low-temperature transport
properties of quantum Hall systems have suggested an interpretation in terms of
liquid crystalline mesophases dubbed {\em quantum Hall liquid crystals}. The
single mode approximation (SMA) has been a useful tool for the determination of
the excitation spectra of various systems such as phonons in He and in the
fractional quantum Hall effect. In this paper we calculate (via the SMA) the
spectrum of collective excitations in a quantum Hall liquid crystal by
considering {\em nematic}, {\em tetratic}, and {\em hexatic} generalizations of
Laughlin's trial wave function having two-, four- and six-fold broken
rotational symmetry, respectively. In the limit of zero wavevector \qq the
dispersion of these modes is singular, with a gap that is dependent on the
direction along which \qq=0 is approached for {\em nematic} and {\em
tetratic} liquid crystalline states, but remains regular in the {\em hexatic}
state, as permitted by the fourth order wavevector dependence of the
(projected) oscillator strength and static structure factor.Comment: 6 pages, 5 eps figures include
The feasibility of sea surface temperature determination using satellite infrared data
Sea surface temperature determination feasibility using satellite infrared dat
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Ontogenetic changes in cutaneous and branchial ionocytes and morphology in yellowfin tuna (Thunnus albacares) larvae.
The development of osmoregulatory and gas exchange organs was studied in larval yellowfin tuna (Thunnus albacares) from 2 to 25 days post-hatching (2.9-24.5 mm standard length, SL). Cutaneous and branchial ionocytes were identified using Na+/K+-ATPase immunostaining and scanning electron microscopy. Cutaneous ionocyte abundance significantly increased with SL, but a reduction in ionocyte size and density resulted in a significant decrease in relative ionocyte area. Cutaneous ionocytes in preflexion larvae had a wide apical opening with extended microvilli; however, microvilli retracted into an apical pit from flexion onward. Lamellae in the gill and pseudobranch were first detected ~ 3.3 mm SL. Ionocytes were always present on the gill arch, first appeared in the filaments and lamellae of the pseudobranch at 3.4 mm SL, and later in gill filaments at 4.2 mm SL, but were never observed in the gill lamellae. Unlike the cutaneous ionocytes, gill and pseudobranch ionocytes had a wide apical opening with extended microvilli throughout larval development. The interlamellar fusion, a specialized gill structure binding the lamellae of ram-ventilating fish, began forming by ~ 24.5 mm SL and contained ionocytes, a localization never before reported. Ionocytes were retained on the lamellar fusions and also found on the filament fusions of larger sub-adult yellowfin tuna; however, sub-adult gill ionocytes had apical pits. These results indicate a shift in gas exchange and NaCl secretion from the skin to branchial organs around the flexion stage, and reveal novel aspects of ionocyte localization and morphology in ram-ventilating fishes
Evaluation of the cardiovascular system during various circulatory stresses Progress report, 1 Sep. 1968 - 1 May 1969
Cardiac response to chemotherapy after myocardial infraction and diagnostic methods of heart disease in man and animal
Iordanskii Force and the Gravitational Aharonov-Bohm effect for a Moving Vortex
I discuss the scattering of phonons by a vortex moving with respect to a
superfluid condensate. This allows us to test the compatibility of the
scattering-theory derivation of the Iordanskii force with the galilean
invariance of the underlying fluid dynamics. In order to obtain the correct
result we must retain terms in the sound-wave equation, and this
reinforces the interpretation, due to Volovik, of the Iordanskii force as an
analogue of the gravitational Bohm-Aharonov effect.Comment: 20 pages, LaTe
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