3,922 research outputs found
Nutrient chemistry of a large, deep lake in subarctic Alaska
Project Officer
Eldor W. Schallock
Assessment and Criteria Development Division
Corvallis Environmental Research Laboratory
Corvallis, Oregon 97330;Corvallis Environmental Research Laboratory
Office of Research and Development
U. S. Environmental Protection Agency
Corvallis, Oregon 97330; R800276The primary objective of this project was to assess the state of the
water quality of Harding Lake, and to attempt to predict the effects of
future development within its watershed. Since the major effect of degradation
of water quality due to human activity is the promotion of nuisance
growths of plants, the major emphasis was placed on measurements of plant
growth and concentrations of the major nutrients they require. Planktonic
algal growth was found to be low, below 95.6 gm/m2/year, and the growth of
submerged rooted plants was found to be relatively less important at approximately
1.35 gm/m2/year. Measurements of the growth of attached algae were
not conducted, therefore the relative importance of their growth is currently
unknown.
A model for predicting the effect of future real estate development in
the watershed was modified and applied to this lake. This model adequately
describes current water quality conditions, and is assumed to have some
predictive ability, but several cautions concerning application of this
model to Harding Lake are discussed.
A secondary objective was to study the thermal regime of a deep subarctic
lake. Intensive water temperature measurements were made throughout
one year and less intensive measurements were conducted during two additional
years. The possibility that this lake may occasionally stratify thermally
under the ice and not mix completely in the spring was discovered. The
implications of this possibility are discussed for management of subarctic
lakes. Hydrologic and energy budgets of this lake are attempted; the annual
heat budget is estimated at 1.96 x 104 ± 1.7 x 103 cal/cm2.
The results of a study of domestic water supply and waste disposal
alternatives in the watershed, and the potential for enteric bacterial contamination
of the lake water are presented. Limited work on the zooplankton,
fishes, and benthic macroinvertebrates of this lake is also presented
Calculated Electron Fluxes at Airplane Altitudes
A precision measurement of atmospheric electron fluxes has been performed on
a Japanese commercial airliner (Enomoto, {\it et al.}, 1991). We have performed
a monte carlo calculation of the cosmic ray secondary electron fluxes expected
in this experiment. The monte carlo uses the hadronic portion of our neutrino
flux cascade program combined with the electromagnetic cascade portion of the
CERN library program GEANT. Our results give good agreement with the data,
provided we boost the overall normalization of the primary cosmic ray flux by
12\% over the normalization used in the neutrino flux calculation.Comment: in REVTEX, 12 pages + 4 figures available upon reques
Bounds on Dark Matter from the ``Atmospheric Neutrino Anomaly''
Bounds are derived on the cross section, flux and energy density of new
particles that may be responsible for the atmospheric neutrino anomaly. Decay of primordial
homogeneous dark matter can be excluded.Comment: 10 pages, TeX (revtex
A Closed-Form Expression for the Gravitational Radiation Rate from Cosmic Strings
We present a new formula for the rate at which cosmic strings lose energy
into gravitational radiation, valid for all piecewise-linear cosmic string
loops. At any time, such a loop is composed of straight segments, each of
which has constant velocity. Any cosmic string loop can be arbitrarily-well
approximated by a piecewise-linear loop with sufficiently large. The
formula is a sum of polynomial and log terms, and is exact when the
effects of gravitational back-reaction are neglected. For a given loop, the
large number of terms makes evaluation ``by hand" impractical, but a computer
or symbolic manipulator yields accurate results. The formula is more accurate
and convenient than previous methods for finding the gravitational radiation
rate, which require numerical evaluation of a four-dimensional integral for
each term in an infinite sum. It also avoids the need to estimate the
contribution from the tail of the infinite sum. The formula has been tested
against all previously published radiation rates for different loop
configurations. In the cases where discrepancies were found, they were due to
errors in the published work. We have isolated and corrected both the analytic
and numerical errors in these cases. To assist future work in this area, a
small catalog of results for some simple loop shapes is provided.Comment: 29 pages TeX, 16 figures and computer C-code available via anonymous
ftp from directory pub/pcasper at alpha1.csd.uwm.edu, WISC-MILW-94-TH-10,
(section 7 has been expanded, two figures added, and minor grammatical
changes made.
High Energy Neutrinos from Cosmological Gamma-Ray Burst Fireballs
Observations suggest that -ray bursts (GRBs) are produced by the
dissipation of the kinetic energy of a relativistic fireball. We show that a
large fraction, , of the fireball energy is expected to be converted
by photo-meson production to a burst of neutrinos. A km^2
neutrino detector would observe at least several tens of events per year
correlated with GRBs, and test for neutrino properties (e.g. flavor
oscillations, for which upward moving 's would be a unique signature, and
coupling to gravity) with an accuracy many orders of magnitude better than is
currently possible.Comment: Submitted to PRL (4 pages, LaTeX
High energy cosmic-rays: puzzles, models, and giga-ton neutrino telescopes
The existence of cosmic rays of energies exceeding 10^20 eV is one of the
mysteries of high energy astrophysics. The spectrum and the high energy to
which it extends rule out almost all suggested source models. The challenges
posed by observations to models for the origin of high energy cosmic rays are
reviewed, and the implications of recent new experimental results are
discussed. Large area high energy cosmic ray detectors and large volume high
energy neutrino detectors currently under construction may resolve the high
energy cosmic ray puzzle, and shed light on the identity and physics of the
most powerful accelerators in the universe.Comment: 12 pages, 7 figures; Summary of review talk, PASCOS 03 (Mumbai,
India
Lepton Flavor Violation at the LHC
Recent results from Super Kamiokande suggest mixing and
hence lepton flavor violation. In supersymmetric models, this flavor violation
may have implications for the pattern of slepton masses and mixings. Possible
signals for this mixing in the decays of sleptons produced at the LHC are
discussed. The sensitivity expected is compared to that of rare decays such as
.Comment: 14 pages, 9 figure
Recommended from our members
Status report on Corsica modeling for current drive scenario development
This milestone report covers the progress and status of Corsica modeling for DIII-D experiments over the past year, since our previous report in September, 1995. During this time, we have concentrated on improvements to the code in support of our ability to do self-consistent, predictive modeling of DIII-D discharges. Our interest is in obtaining a tool, benchmarked with experimental data, for developing advanced tokamak operations scenarios including simulation and analysis of high performance negative central shear (NCS) discharges and control of the current profile evolution. Our major focus has been on installing and improving the neutral beam current drive mode in Corsica; this element is critical to modeling the evolution of DIII-D discharges. The NFREYA neutral beam deposition code was installed (starting with a version consistent with GA`s ONETWO code) and the capability for following particle orbits, including the effects of drifts, was added for determining the current driven by neutral beam -injection. In addition, improved methods for more easily integrating experimental profile measurements into the code operation and for calculating Z{sub eff} either from models or from impurity density measurements have been added. We have recently begun to turn on various transport models in our simulation of discharge evolution. We have concentrated on the NCS configuration and have simulated the evolution of two different high neutron reactivity discharges; an NCS discharge with L-mode edge and a single- null, weak NCS discharge from the JET/ITER/DIII-D equivalent shape experiments. Corsica simulation results for these discharges were presented at the EPS meeting in Kiev, Ukraine in June, 1996
CP and T violation test in neutrino oscillation
We examine how large violation of CP and T is allowed in long base line
neutrino experiments. When we attribute only the atmospheric neutrino anomaly
to neutrino oscillation we may have large CP violation effect. When we
attribute both the atmospheric neutrino anomaly and the solar neutrino deficit
to neutrino oscillation we may have a sizable T violation effect proportional
to the ratio of two mass differences; it is difficult to see CP violation since
we can't ignore the matter effect. We give a simple expression for T violation
in the presence of matter.Comment: 12 pages + 2 eps figures, Latex, In order to avoid misunderstanding
we have refined our English and rewritten the parts which might be
misleading. Several typographical errors are correcte
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