3,649 research outputs found
Decreased Performance of Rainbow Trout Oncorhynchus mykiss Emergence Behaviors Following Embryonic Exposure to Benzo[a]pyrene
Peer reviewed
The original version of this paper is available from NOAA https://spo.nmfs.noaa.gov/content/decreased-performance-rainbow-trout-oncorhynchus-mykiss-emergence-behaviors-following
Citation: Ostrander, G. K., Anderson, J. J., Fisher, J. P., Landolt, M. L., & Kocan, R. M. (1990). Decreased performance of rainbow trout Oncorhynchus mykiss emergence behaviors following embryonic exposure to benzo (z) pyrene. Fishery Bulletin, 88(3), 551-555.The sublethal effects induced by a model carcinogen and environmental contaminant on salmonid emergence behaviors have been studied. Rainbow trout embryos were exposed for 24 hours to 25 IAg/mL of benzo[a)pyrene 1 week prior to hatching. Exposures occurred during the late organogenesis period of development and allowed assessment of how a single embryonic exposure might affect emergence behaviors nearly 6 weeks later. Though no differences in numbers of alevins successfully emerging were observed, a significant decrease was noted in performance of the upstream orientation behaviors characteristic ofemergence among wild individuals.These findings are discussed in terms ofa model describing the role of upstream swimming behavior after emergence
Shape Space Methods for Quantum Cosmological Triangleland
With toy modelling of conceptual aspects of quantum cosmology and the problem
of time in quantum gravity in mind, I study the classical and quantum dynamics
of the pure-shape (i.e. scale-free) triangle formed by 3 particles in 2-d. I do
so by importing techniques to the triangle model from the corresponding 4
particles in 1-d model, using the fact that both have 2-spheres for shape
spaces, though the latter has a trivial realization whilst the former has a
more involved Hopf (or Dragt) type realization. I furthermore interpret the
ensuing Dragt-type coordinates as shape quantities: a measure of
anisoscelesness, the ellipticity of the base and apex's moments of inertia, and
a quantity proportional to the area of the triangle. I promote these quantities
at the quantum level to operators whose expectation and spread are then useful
in understanding the quantum states of the system. Additionally, I tessellate
the 2-sphere by its physical interpretation as the shape space of triangles,
and then use this as a back-cloth from which to read off the interpretation of
dynamical trajectories, potentials and wavefunctions. I include applications to
timeless approaches to the problem of time and to the role of uniform states in
quantum cosmological modelling.Comment: A shorter version, as per the first stage in the refereeing process,
and containing some new reference
Charge degrees in the quarter-filled checkerboard lattice
For a systematic study of charge degrees of freedom in lattices with
geometric frustration, we consider spinless fermions on the checkerboard
lattice with nearest-neighbor hopping and nearest-neighbor repulsion at
quarter-filling. An effective Hamiltonian for the limit is given to
lowest non-vanishing order by the ring exchange (). We show
that the system can equivalently be described by hard-core bosons and map the
model to a confining U(1) lattice gauge theory.Comment: Proceedings of ICM200
Relativistic Solenoids
We construct a general relativistic analogy of an infinite solenoid, i.e., of
an infinite cylinder with zero electric charge and non-zero electric current in
the direction tangential to the cylinder and perpendicular to its axis. We
further show that the solution has a good weak-field limit.Comment: 9 pages, 2 figure
Symmetric angular momentum coupling, the quantum volume operator and the 7-spin network: a computational perspective
A unified vision of the symmetric coupling of angular momenta and of the
quantum mechanical volume operator is illustrated. The focus is on the quantum
mechanical angular momentum theory of Wigner's 6j symbols and on the volume
operator of the symmetric coupling in spin network approaches: here, crucial to
our presentation are an appreciation of the role of the Racah sum rule and the
simplification arising from the use of Regge symmetry. The projective geometry
approach permits the introduction of a symmetric representation of a network of
seven spins or angular momenta. Results of extensive computational
investigations are summarized, presented and briefly discussed.Comment: 15 pages, 10 figures, presented at ICCSA 2014, 14th International
Conference on Computational Science and Application
Stimulation of Beta Decay due to a Bose-Einstein Condensate
Nuclear processes can be stimulated by the presence of a macroscopic number
of bosons in one of the final states. We describe the conditions necessary to
observe the atom-stimulation of a beta decay process. The stimulation may be
observable if it becomes possible to produce a Bose-Einstein condensate with
the order of atoms in a trap.Comment: 7 pages, LaTeX, uses elsart.cls, home page at
http://online.anu.edu.au/Physics/Welcome.htm
The use of large undisturbed cores to assess soil quality-yield relationships in the greenhouse
Non-Peer ReviewedLarge undisturbed cores were taken from different landscape positions (divergent shoulders, DSH, and convergent footslopes, CFS) at two sites in the Black soil zone. The soils are classified as belonging to the Oxbow association and have been cultivated for 15 and 82 years. The cores were used in a greenhouse experiment to study the effect of soil quality on yield of spring wheat (var. Katepwa) at three levels of simulated growing season precipitation: low (123 mm season-1), mid (189 mm season-1), and high (332 mm season-1). Grain yields in the DSH cores increased with increasing precipitation for both the 15- and 82-year soils. Moreover, the 15-year DSH cores out-yielded their 82-year counterparts by 50, 76, and 85% at the low, mid, and high water levels, respectively. Cores from the CFS positions were watered only at the mid-water level. Grain yields in the 15- and 82-year CFS cores and the 15-year DSH cores were not significantly different (P < 0.05). The results of this study indicate that soil quality is a relatively minor factor when water is limiting but assumes a much greater role in years of normal or above normal growing season precipitation. These initial results also suggest that large cores are a feasible and cost-effective means of studying soil-plant relationships in the greenhouse or growth chamber
Developing simplified synergistic relationships to model topsoil erosion and crop yield
Non-Peer ReviewedTopsoil is highly enriched with organic matter, which provides a valuable source of plant nutrients as well as a favorable rooting environment. Over time, erosion processes selectively remove the organic matter-rich fine fraction which causes a measurable reduction in soil productivity. Assessments of past erosion are
of little value in predicting future losses in productivity since the synergistic lowering of soil organic matter through lower residue inputs is not considered. Dynamic computer models, which simulate the plant/soil system, can project the long run future costs of soil erosion on crop yield. A simplified erosion-crop yield
model was developed by first defining the most important soil productivity variables, then quantifying the effect of erosion on each variable. The model predicted a declining trend in grain yields similar to that observed on soil scalping experiments
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