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Fractal templates in the escape dynamics of trapped ultracold atoms
We consider the dynamic escape of a small packet of ultracold atoms launched
from within an optical dipole trap. Based on a theoretical analysis of the
underlying nonlinear dynamics, we predict that fractal behavior can be seen in
the escape data. This data would be collected by measuring the time-dependent
escape rate for packets launched over a range of angles. This fractal pattern
is particularly well resolved below the Bose-Einstein transition temperature--a
direct result of the extreme phase space localization of the condensate. We
predict that several self-similar layers of this novel fractal should be
measurable and we explain how this fractal pattern can be predicted and
analyzed with recently developed techniques in symbolic dynamics.Comment: 11 pages with 5 figure
Derivation of the Gauge Link in Light Cone Gauge
In light cone gauge, a gauge link at light cone infinity is necessary for
transverse momentum-dependent parton distribution to restore the gauge
invariance in some specific boundary conditions. We derive such transverse
gauge link in a more regular and general method. We find the gauge link at
light cone infinity naturally arises from the contribution of the pinched
poles: one is from the quark propagator and the other is hidden in the gauge
vector field in light cone gauge. Actually, in the amplitude level, we have
obtained a more general gauge link over the hypersurface at light cone infinity
which is beyond the transverse direction. The difference of such gauge link
between semi-inclusive deep inelastic scattering and Drell-Yan processes can
also be obtained directly and clearly in our derivation.Comment: 18 pages, 5 figures, published versio
Medical Information Management System (MIMS): An automated hospital information system
Flexible system of computer programs allows manipulation and retrieval of data related to patient care. System is written in version of FORTRAN developed for CDC-6600 computer
Effects of ionizing radiation on CCD's
The effects of 1.2 MeV gamma radiation and 20 MeV electrons on the operational characteristics of CCDs are studied. The effects of ionizing radiation on the charge transfer efficiency, dark current, and input/output circuitry are described. The improved radiation hardness of buried channel CCDs is compared to surface channel results. Both ion implanted and epitaxial layer buried channel device results are included. The advantages of using a single thickness SiO2 gate dielectric are described. The threshold voltage shifts and surface state density changes of dry, steam, and HCl doped oxides are discussed. Recent results on the recovery times and total dose effects of high dose rate pulses of 20 MeV electrons are reported
The Purple Haze of Eta Carinae: Binary-Induced Variability?
Asymmetric variability in ultraviolet images of the Homunculus obtained with
the Advanced Camera for Surveys/High Resolution Camera on the Hubble Space
Telescope suggests that Eta Carinae is indeed a binary system. Images obtained
before, during, and after the recent ``spectroscopic event'' in 2003.5 show
alternating patterns of bright spots and shadows on opposite sides of the star
before and after the event, providing a strong geometric argument for an
azimuthally-evolving, asymmetric UV radiation field as one might predict in
some binary models. The simplest interpretation of these UV images, where
excess UV escapes from the secondary star in the direction away from the
primary, places the major axis of the eccentric orbit roughly perpendicular to
our line of sight, sharing the same equatorial plane as the Homunculus, and
with apastron for the hot secondary star oriented toward the southwest of the
primary. However, other orbital orientations may be allowed with more
complicated geometries. Selective UV illumination of the wind and ejecta may be
partly responsible for line profile variations seen in spectra. The brightness
asymmetries cannot be explained plausibly with delays due to light travel time
alone, so a single-star model would require a seriously asymmetric shell
ejection.Comment: 8 pages, fig 1 in color, accepted by ApJ Letter
Pacific bonito management information document
Management of Pacific bonito in California is examined in this Management Information Document by a State-Federal team of scientists.
Abundance of Pacific bonito in southern California has fallen dramatically between the 1963-1969 period and the 1974-1977 period. Since 1976 the commercia1 fleet has found few large fish in southern California, and has caught fish in the size range of 15 to 57 cm (1.2 to 4.7 pounds). This fact, coupled with the low abundance indices, point out the need for a more active management regime.
To develop management measures for the California bonito
fishery both a surplus yield analysis and a yield-per-recruit analysis were performed. A maximum sustained yield of 10,000 short tons was estimated for the fishery in southern California, while the whole fishery, including Baja California, has an estimated MSY of 13,000 tons. In order to achieve this level of catch, however, the stock abundance must be increased by a factor of five.
Yield-per-recruit considerations suggest that a minimum
size limit in the commercial fishery has two important effects. A three-pound size limit could result in a slight increase in yield-per-recruit. If the size limit is increased to 5 or 7.5 lbs, the yield-per-recruit would fall significantly. Offsetting the effect on yield-per-recruit, however, would be a substantial increase in average amount of spawning per recruit which should result in a proportional increase in recruitment. With the current depressed stock abundance both a reduced annual take and
a minimum size limit on commercial catch would confer
substantial benefits in the form of an increase in the future stock size.
After considering seven different types of management
measures, the team finds that three types -- an annual commercial catch quota, a commercial size limit, and a recreational bag limit -- appear desirable.
Re-establishment of the stock in southern California was
the major consideration in this evaluation because the stock is currently depressed. All segments of the fishery will benefit from a more abundant resource. The difficult issues for policy, however, concern the rate of rebuilding, the degree of risk that is acceptable, and the distribution of benefits among user groups. By judicious choice among the options discussed here, a variety of positions can be established with respect to these issues. The greater the
size limit, for instance, the more benefit is provided the
recreational sector while difficulties are imposed upon commercial fishermen. The higher the quotas adopted, the
slower the stock rebuilding and the greater the risk of continued stock depletion. A final reconciliation of the management options involves social, political and legal considerations which must be thoroughly incorporated by decision-makers before adoption of a management plan. (93pp.
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