799 research outputs found
Integration of technologies for understanding the functional relationship between reef habitat and fish growth and production
Functional linkage between reef habitat quality and fish growth and production has remained elusive. Most current research is focused on correlative relationships between a general habitat type and presence/absence of a species,
an index of species abundance, or species diversity. Such descriptive information largely ignores how reef attributes
regulate reef fish abundance (density-dependent habitat selection), trophic interactions, and physiological performance (growth and condition). To determine the
functional relationship between habitat quality, fish abundance, trophic interactions, and physiological performance, we are using an experimental reef system in
the northeastern Gulf of Mexico where we apply advanced sensor and biochemical technologies. Our study site controls for reef attributes (size, cavity space, and reef
mosaics) and focuses on the processes that regulate gag grouper (Mycteroperca microlepis) abundance, behavior and performance (growth and condition), and the availability of their pelagic prey. We combine mobile and fixed-active (fisheries) acoustics, passive acoustics, video cameras,
and advanced biochemical techniques. Fisheries acoustics quantifies the abundance of pelagic prey fishes associated
with the reefs and their behavior. Passive acoustics and video allow direct observation of gag and prey fish behavior and the acoustic environment, and provide a
direct visual for the interpretation of fixed fisheries acoustics measurements. New application of biochemical techniques, such as Electron Transport System (ETS) assay,
allow the in situ measurement of metabolic expenditure of gag and relates this back to reef attributes, gag behavior, and prey fish availability. Here, we provide an overview of our integrated technological approach for understanding and quantifying the functional relationship between reef habitat quality and one element of production – gag grouper growth on shallow coastal reefs
NASA/FAA helicopter simulator workshop
A workshop was convened by the FAA and NASA for the purpose of providing a forum at which leading designers, manufacturers, and users of helicopter simulators could initiate and participate in a development process that would facilitate the formulation of qualification standards by the regulatory agency. Formal papers were presented, special topics were discussed in breakout sessions, and a draft FAA advisory circular defining specifications for helicopter simulators was presented and discussed. A working group of volunteers was formed to work with the National Simulator Program Office to develop a final version of the circular. The workshop attracted 90 individuals from a constituency of simulator manufacturers, training organizations, the military, civil regulators, research scientists, and five foreign countries
Part 1: Executive summary
A workshop was convened by the FAA and NASA for the purpose of providing a forum at which leading designers, manufacturers, and users of helicopter simulators could initiate and participate in a development process that would facilitate the formulation of qualification standards by the regulatory agency. Formal papers were presented, special topics were discussed in breakout sessions, and a draft FAA advisory circular defining specifications for helicopter simulators was presented and discussed. A working group of volunteers was formed to work with the National Simulator Program Office to develop a final version of the circular. The workshop attracted 90 individuals from a constituency of simulator manufacturers, training organizations, the military, civil regulators, research scientists, and five foreign countries. A great amount of information was generated and recorded verbatim. This information is presented herein within the limits of accuracy inherent in recording, transcribing, and editing spoken technical material
The structure of the hydrated electron. Part 2. A mixed quantum classical molecular dynamics - embedded cluster density functional theory: single-excitation configuration interaction study
Adiabatic mixed quantum/classical molecular dynamics simulations were used to
generate snapshots of the hydrated electron (e-) in liquid water at 300 K.
Water cluster anions that include two complete solvation shells centered on the
e- were extracted from these simulations and embedded in a matrix of fractional
point charges designed to represent the rest of the solvent. Density functional
theory and single-excitation configuration interaction methods were then
applied to these embedded clusters. The salient feature of these hybrid
calculations is significant transfer (ca. 0.18) of the excess electron's charge
density into the O 2p orbitals in OH groups forming the solvation cavity. We
used the results of these calculations to examine the structure of the
molecular orbitals, the density of states, the absorption spectra in the
visible and ultraviolet, the hyperfine coupling (hfc) tensors, and the IR and
Raman spectra of the e-. The calculated hfc tensors were used to compute the
EPR and ESEEM spectra for the e- that compared favorably to the experimental
spectra of trapped e- in alkaline ice. The calculated vibrational spectra of
the e- are consistent with the red-shifted bending and stretching frequencies
observed in resonance Raman experiments. The model also accounts for the VIS
and 190-nm absorption bands of the e-. Thus, our study suggests that to explain
several important experimentally observed properties of the e-, many-electron
effects must be accounted for.Comment: 68 pages, 12 figures + 16 more figures in the supplement (included)
submitted to J Phys Chem
Short-term and long-term effects of transient exogenous cortisol manipulation on oxidative stress in juvenile brown trout
In the wild, animals are exposed to a growing number of stressors with increasing frequency and intensity, as a result of human activities and human-induced environmental change. To fully understand how wild organisms are affected by stressors, it is crucial to understand the physiology that underlies an organism’s response to a stressor. Prolonged levels of elevated glucocorticoids are associated with a state of chronic stress and decreased fitness. Exogenous glucocorticoid manipulation reduces an individual’s ability to forage, avoid predators and grow, thereby limiting the resources available for physiological functions like the defence against oxidative stress. Using the brown trout (Salmo trutta), we evaluated the short-term (2 weeks) and long-term (4 months over winter) effects of exogenous cortisol manipulations (as well as relevant shams and controls) on the oxidative status of wild juveniles. Cortisol caused an increase in glutathione over a two-week period and appeared to reduce glutathione over winter. Cortisol treatment did not affect oxidative stress levels or low-molecular weight antioxidants. Cortisol caused a significant decrease in growth rates but did not affect predation risk. Over winter survival in the stream was associated with low levels of oxidative stress and glutathione. Thus, oxidative stress may be a mechanism by which elevated cortisol causes negative physiological consequences.</jats:p
Measuring the cosmological lepton asymmetry through the CMB anisotropy
A large lepton asymmetry in the Universe is still a viable possibility and
leads to many interesting phenomena such as gauge symmetry nonrestoration at
high temperature. We show that a large lepton asymmetry changes the predicted
cosmic microwave background (CMB) anisotropy and that any degeneracy in the
relic neutrino sea will be measured to a precision of 1% or better when the CMB
anisotropy is measured at the accuracy expected to result from the planned
satellite missions MAP and Planck. In fact, the current measurements already
put an upper limit on the lepton asymmetry of the Universe which is stronger
than the one coming from considerations of primordial nucleosynthesis and
structure formation.Comment: 4 pagex LaTex, 1 color postscript figure, uses epsf. Version
submitted to PRL. (Bug in code fixed, new figure, conclusions unchanged
Research Space at Public R1 Universities in the Mountain West, 2021
This fact sheet reports data on research space square footage for public R1 universities in five Mountain West States: Arizona, Colorado, Nevada, New Mexico, and Utah. This fact sheet includes national rankings of public R1 universities in the Mountain West states based on total square footage and reports square footage for individual research disciplines for the two public R1 universities in Nevada: the University of Nevada, Las Vegas (UNLV) and the University of Nevada, Reno (UNR)
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