A standard fast reactor spectrum can be created by the partial moderation of the U-235 fission spectrum in an air cavity. Spherical natural uranium shells are driven by thermal neutrons from a thermal column. The uranium is placed at the center of a spherical graphite hohlraum to reduce the anisotropic...
The uptake of hydrogen by lanthanum pentanickel (LaNi₅) to form lanthanum nickel hydride (LaNi₅H₆) is
followed with three-dimensional imaging by neutron tomography. The hydrogen absorption process is
slower than the time needed for acquiring a single radiograph, about 10 s, but fast relative to the time
to acquire a fully-sampled...
Paleozoic limestones, dolomites, quartz arenites, and other
clastic rocks were mapped in the vicinity of Dobbin Summit and
Clear Creek in the central Monitor Range. Sedimentary rock units
present in this area represent the shallow-shelf eastern assemblage
and basin and also the basin-slope facies of the traditional limestoneclastic
assemblage.
The...
Devonian carbonate rocks of the southern Hot Creek Range reflect a shift to the east of the carbonate shelf edge and a progressively deeper-water lithotope from late
Early Devonian to early Middle Devonian time. Lower Devonian mudstones of the McColley Canyon Formation were deposited on an open shelf, dolomitized, and...
A digital computer model was developed to simulate the time
and space distribution of a dissolved pollutant in an estuary. The program
is basically a one-dimensional finite-difference model, but two
dimensions can be represented by attaching together several one-dimensional
channels. The influence of convection, dispersion and
decay are included in...
Mathematical modeling of phytoplankton populations based on laboratory observations provides increased understanding of the interaction among the environmental and biological mechanisms. influencing growth dynamics. Such fundamental understanding is necessary to estimate the impact of man-made perturbations on natural population.
A three-compartment mathematical model was developed to represent a phytoplankton population...
Small rivers, such as those that line the Oregon coast, have been shown to deliver significant concentrations of suspended sediments and nutrients to estuaries and the coastal ocean during wet seasons during which winds are predominantly downwelling-favorable. The fate of the buoyant source water and of any suspended or dissolved...
Advancements in digital detector technology over the past decade have facilitated the transition of mammography image acquisition from film screen to full field digital applications. Nearly 90% of the mammography performed in the United States utilizes digital imaging technologies. The ability to capture the image information in an electronic format...
Golden paintbrush (Castilleja levisecta Greenman) historically inhabited the prairies of the Willamette Valley, Oregon. However, this Pacific Northwest endemic is currently restricted to eleven sites in the Puget Trough of Washington and British Columbia. Recovery criteria call for the establishment of new populations throughout the species historic range, including the...