10,082 research outputs found
Evaporation of Three Dimensional Black Hole in Quantum Gravity
We discuss an evaporation of (2+1)-dimensional black hole by using quantum
gravity holding in the vicinity of the black hole horizon. It is shown that the
black hole evaporates at a definite rate by emitting matters through the
quantum tunneling effect. A relation of the present formalism to the black hole
entropy is briefly commented.Comment: 13 pages, phyzz
The Pacific herring, Clupea harengus pallasi, open pound roe-on-kelp experimental fishery in San Francisco Bay, 1988 to 1989
The experimental open pound herring roe-on-kelp
(ROK) fishery was studied in San Francisco Bay from
the second week of December 1988 through the third
week of February 1989.
Three spawning runs were fished successfully by
four operations consisting of six permittees. A
total of 47.1 tons of herring ROK was packed this
season.
Giant kelp, Macrocystis sp., was harvested from the
Santa Barbara Channel Islands and trucked to San
Francisco for hanging on the pounds. Sources of
high-quality giant kelp in California were
difficult to locate this season because of
unfavorable oceanographic conditions during the
winter months.
ROK was sampled at each shoreside processing
facility. There were no significant differences in
ROK blade measurements or roe densities among the
permittees. ROK densities ranged from 0.250 to
0.699 g/cm2.
Plastic totes containing processed ROK averaged
1756 lbs total gross weight. Totes contained an
average of 42.3% ROK by weight.
Siltation of ROK harvested in south San Francisco
Bay continued to be a problem. High winds damaged
rafts in December 1988. Gear conflicts were
reported between ROK and herring roe permittees. (25pp.
Topological Symmetry, Background Independence, and Matrix Models
We illustrate a physical situation in which topological symmetry, its
breakdown, space-time uncertainty principle, and background independence may
play an important role in constructing and understanding matrix models. First,
we show that the space-time uncertainty principle of string may be understood
as a manifestation of the breakdown of the topological symmetry in the large
matrix model. Next, we construct a new type of matrix models which is a
matrix model analog of the topological Chern-Simons and BF theories. It is of
interest that these topological matrix models are not only completely
independent of the background metric but also have nontrivial "p-brane"
solutions as well as commuting classical space-time as the classical solutions.
In this paper, we would like to point out some elementary and unsolved problems
associated to the matrix models, whose resolution would lead to the more
satisfying matrix model in future.Comment: 19 pages, LaTex, Invited paper to appear in the special issue of the
Journal of Chaos, Solitons and Fractals on "Superstrings, M, F, S, .......
Theory", edited by M.S. El Naschie and C. Castr
Pacific herring, Clupea harengus pallasi, studies in San Francisco and Tomales Bays, April 1989 to March 1990
Herring schools were surveyed hydroacoustically in
San Francisco Bay from early November 1989 through
mid March 1990. Seven large schools (>1000 tons) and
two smaller ones were detected. The total acoustic
biomass estimate based on visual integration was
58,100 tons. Merging with the independent spawn
escapement estimate yielded a "best" estimate of
64,500 tons.
Sixty-three samples, containing 10,239 herring, were
collected. Patterns evident in prior seasons
continue. Larger, older fish continue to dominate
early season schools. Males continue to be
numerically superior during the first half of the
season. Mean size and weight at age suggest
conditions following the 1988-89 season were not
favorable for growth.
Contrary to forecasts, the 1988 year class
recruitment strength was high; second only to the
1982 year class. Although still being validated,
forecasts suggest the 1989 year class will be strong
and the 1990 year class will be extremely weak. (64pp.
Introducing Dynamical Triangulations to the Type IIB Superstrings
In order to consider non-perturbative effects of superstrings, we try to
apply dynamical triangulations to the type IIB superstrings. The discretized
action is constructed from the type IIB matrix model proposed as a constructive
definition of superstring theory. The action has the local N=2 supersymmetry
explicitly, and has no extra fermionic degrees of freedom. We evaluate the
partition function for some simple configurations and discuss constraints
required from the finiteness of partition functions.Comment: LATTICE99, 3 pages, LaTeX with 2 figures, espcrc2.st
Grand-canonical simulation of two-dimensional simplicial gravity
The string susceptibility exponents of dynamically triangulated 2-dimensional
surfaces with various topologies, such as a sphere, torus and double-torus,
were calculated by the grand-canonical Monte Carlo method. These simulations
were made for surfaces coupled to -Ising spins (=0,1,2,3,5). In each
simulation the area of surface was constrained to within 1000 to 3000 of
triangles, while maintaining the detailed-balance condition. The numerical
results show excellent agreement with theoretical predictions as long as .Comment: 9 pages, Latex include 5 postscript figures, using psfig.sty and
cite.st
Black Hole Thermodynamics from String Theory
In this note we consider a stringy description of black hole horizon. We
start with a nonlinear sigma model defined on a two dimensional Euclidean
surface with background Rindler metric. By solving the field equations, we show
that to the leading order the Bekenstein-Hawking formula of black hole entropy
can be produced. We also point out a relation between the present formalism and
the 'tHooft formalism.Comment: 11, EDO-EP-
Pacific Herring, Clupea pallasi, spawning population assessment for San Francisco Bay, 1992-93
We conducted hydroacoustic surveys, spawn surveys, and sampled schools and fishery landings from 8 November 1992 through 18 March 1993 to assess the status of San Francisco
Bay's Pacific herring spawning population. Our spawning biomass estimate of 21,186 tons is the lowest since 1978 when subtidal spawns were included in estimates; it also
represents a third consecutive season of decline. The principal reason for this very low estimate is a lack of two-, three-, and four-year-old herring in the spawning population from the 1991,1990, and 1989 year-classes. Although four-year-olds were the most abundant cohort, their actual number was very low. Five-year-olds from the highly successful 1988 year-class were the second most abundant cohort.
Warm-water conditions and poor upwelling associated with the 1991-92 El Nino are likely causes of the low spawning biomass, although adverse impacts on the condition and
growth of spawners were not apparent. Warm water may have displaced herring to the north of San Francisco Bay.
We also continued to collect data for a herring young-of-the-year abundance index during April, May, and June of 1993. The index was low for the 1990 and 1991 year-classes, but high for the 1989 year-class. The 1989 and 1990 year-classes appear poor; however, the success of the 1991 year-class will not be known until next season when it fully recruits to the spawning population.The index for the 1992 year-class is relatively low as is the index for 1993.
The season's 5,555-ton quota (based on the previous season's biomass estimate) exceeded our harvest goal of no more than 20% of spawning biomass for the first time since the 1970s. The number of three-year-old fish in gill net catches increased substantially this season, possibly indicating the use of smaller mesh.
Because of the extremely low spawning biomass and uncertainty about future recruitment, our recommendation to the Fish and Game Commission was to close the herring roe
fishery in San Francisco Bay until the season following a spawning biomass estimate of 26,000 tons. (30pp.
Locally Localized Gravity Models in Higher Dimensions
We explore the possibility of generalizing the locally localized gravity
model in five space-time dimensions to arbitrary higher dimensions. In a
space-time with negative cosmological constant, there are essentially two kinds
of higher-dimensional cousins which not only take an analytic form but also are
free from the naked curvature singularity in a whole bulk space-time. One
cousin is a trivial extension of five-dimensional model, while the other one is
in essence in higher dimensions. One interesting observation is that in the
latter model, only anti-de Sitter () brane is physically meaningful
whereas de Sitter () and Minkowski () branes are dismissed.
Moreover, for brane in the latter model, we study the property of
localization of various bulk fields on a single brane. In particular, it is
shown that the presence of the brane cosmological constant enables bulk gauge
field and massless fermions to confine to the brane only by a gravitational
interaction. We find a novel relation between mass of brane gauge field and the
brane cosmological constant.Comment: 20 pages, LaTex 2e, revised version (to appear in Phys. Rev. D
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