4,259 research outputs found
Nematic Order by Disorder in Spin-2 BECs
The effect of quantum and thermal fluctuations on the phase diagram of spin-2
BECs is examined. They are found to play an important role in the nematic part
of the phase diagram, where a mean-field treatment of two-body interactions is
unable to lift the accidental degeneracy between nematic states. Quantum and
thermal fluctuations resolve this degeneracy, selecting the uniaxial nematic
state, for scattering lengths , and the square biaxial nematic state
for . Paradoxically, the fluctuation induced order is stronger at
higher temperatures, for a range of temperatures below . For the
experimentally relevant cases of spin-2 Rb and Na, we argue that
such fluctuations could successfully compete against other effects like the
quadratic Zeeman field, and stabilize the uniaxial phase for experimentally
realistic conditions. A continuous transition of the Ising type from uniaxial
to square biaxial order is predicted on raising the magnetic field. These
systems present a promising experimental opportunity to realize the `order by
disorder' phenomenon.Comment: 5 pages, 4 figures; 1 reference and 1 minor correctio
On The Linearity of The Black Hole - Bulge Mass Relation in Active and in Nearby Galaxies
Analysis of PG quasar observations suggests a nonlinear relation between the
black hole mass, M_BH, and the bulge mass, M_bulge, although a linear relation,
as proposed for nearby galaxies, cannot be ruled out. New M_BH values for
nearby galaxies from Gebhardt et al., and L_bulge measurements for Seyfert 1
galaxies from Virani et al., are used here to obtain a more accurate value for
the slope of the M_BH-M_bulge relation. The combined sample of 40 active and
non-active galaxies suggests a significantly nonlinear relation, M_BH\propto
M_bulge^{1.53\pm 0.14}. Further support for a nonlinear relation is provided by
the slope of the M_BH-stellar velocity dispersion relation found recently, and
by the low M_BH found in late type spiral galaxies. The mean M_BH/M_bulge ratio
is therefore not a universal constant, but rather drops from ~0.5% in bright
(M_V ~ -22) ellipticals, to ~0.05% in low luminosity (M_V ~ -18) bulges. Hubble
Space Telescope determinations of M_BH in late type spirals, and of the bulge
magnitude in narrow line Seyfert 1 galaxies (both predicted to have low M_BH),
can further test the validity of the nonlinear M_BH-M_bulge relation.Comment: Accepted for publication in ApJ, 9 pages inc. 2 figure
Sensitivity Analysis of Transportation Production Costs in Indonesia
The transportation production cost (TPC) considerably has strong influence to the national economic condition. This paper focused on the analysis of the transportation production cost sensitivity in relation to the variation of the external affecting factor, which are fuel price, rupiah exchange rate and Bank of Indonesia interest rate. Based on the R2 values, the TPC components in general have significant correlation, with the fuel prices. However, they do not have high correlation to the fluctuation of interest rate and rupiah exchange rate. The sensitivity analysis shows that a 10% rise on fuel price would cause 6%, 2%, 7%, 2.4%, and 4.9% rise on the TPC of intercity bus, ferry ship, interisland ship, train, and airline, respectively
- …