44 research outputs found
Rayleigh-Taylor instability of crystallization waves at the superfluid-solid 4He interface
At the superfluid-solid 4He interface there exist crystallization waves
having much in common with gravitational-capillary waves at the interface
between two normal fluids. The Rayleigh-Taylor instability is an instability of
the interface which can be realized when the lighter fluid is propelling the
heavier one. We investigate here the analogues of the Rayleigh-Taylor
instability for the superfluid-solid 4He interface. In the case of a uniformly
accelerated interface the instability occurs only for a growing solid phase
when the magnitude of the acceleration exceeds some critical value independent
of the surface stiffness. For the Richtmyer-Meshkov limiting case of an
impulsively accelerated interface, the onset of instability does not depend on
the sign of the interface acceleration. In both cases the effect of
crystallization wave damping is to reduce the perturbation growth-rate of the
Taylor unstable interface.Comment: 8 pages, 2 figures, RevTe
Hydrodynamic instability during non-uniform growth of a helium crystal
We analyze an analog of the hydrodynamic Rayleigh-Taylor instability for the
liquid-solid phase interface under non-uniform growth of the solid phase. The
development of the instability starts on conditions of an accelerated interface
growth and if the magnitude of acceleration exceeds some critical value. The
plane and spherical shapes of the interface are considered. The observation of
the instability can be expected for helium crystals in the course of their
abnormal fast growth.Comment: Revtex, 5 pages, 3 figure
Underbarrier nucleation kinetics in a metastable quantum liquid near the spinodal
We develop a theory in order to describe the effect of relaxation in a
condensed medium upon the quantum decay of a metastable liquid near the
spinodal at low temperatures. We find that both the regime and the rate of
quantum nucleation strongly depend on the relaxation time and its temperature
behavior. The quantum nucleation rate slows down with the decrease of the
relaxation time. We also discuss the low temperature experiments on cavitation
in normal He and superfluid He at negative pressures. It is the sharp
distinctions in the high frequency sound mode and in the temperature behavior
of the relaxation time that make the quantum cavitation kinetics in He and
He completely different in kind.Comment: 10 pages, 2 figure
Improved Single Sector Supersymmetry Breaking
Building on recent work by N. Arkani-Hamed and the present authors, we
construct realistic models that break supersymmetry dynamically and give rise
to composite quarks and leptons, all in a single strongly-coupled sector. The
most important improvement compared to earlier models is that the
second-generation composite states correspond to dimension-2 "meson" operators
in the ultraviolet. This leads to a higher scale for flavor physics, and gives
a completely natural suppression of flavor-changing neutral currents. We also
construct models in which the hierarchy of Yukawa couplings is explained by the
dimensionality of composite states. These models provide an interesting and
viable alternative to gravity- and gauge-mediated models. The generic
signatures are unification of scalar masses with different quantum numbers at
the compositeness scale, and lighter gaugino, Higgsino, and third-generation
squark and slepton masses. We also analyze large classes of models that give
rise to both compositeness and supersymmetry breaking, based on gauge theories
with confining, fixed-point, or free-magnetic dynamics.Comment: 34 pages, LaTeX2
Identification and Structural Characterization of a New Three-Finger Toxin Hemachatoxin from Hemachatus haemachatus Venom
10.1371/journal.pone.0048112PLoS ONE710