The effects of link annotations on user search performance in hypertext environments having deep (layered) and shallow link structures were investigated in this study. Four environments were tested—layered-annotated, layered-unannotated, shallow-annotated, and shallow-unannotated. A single document was divided into 48 sections, and layered and unlayered versions were created. Additional version...

Differences in water-acquisition strategies of tree root systems can determine the capacity to survive under severe drought. We evaluate the effects of field water shortage on early survival, growth and root morphological variables of two South American Mediterranean tree species with different rooting strategies during two growing seasons. One year-old Quillaja saponaria (deep-rooted) and Cryp...

Coastal methane hydrate deposits are globally abundant. There is a need to understand the deep sediment sourced methane energy contribution to shallow sediment carbon relative to terrestrial sources and phytoplankton. Shallow sediment and porewater samples were collected from Atwater Valley, Texas-Louisiana Shelf, Gulf of Mexico near a seafloor mound feature identified in geophysical surveys as...

Ecosystem-level effects of stressors are critical to understanding community regulation, and environmental stress models are useful in describing such effects. Hypoxia is an important stressor in aquatic ecosystems that usually decreases abundance and biomass of benthic fauna. In field surveys, predator abundance is low in hypoxic areas, and in lab experiments, predators reduce their feeding ra...

Yinggehai Basin is an elongate Cenozoic rift basin on the northwestern margin of the South China Sea continental shelf. Its thick ( 17 km) basin fill is characterized by high geothermal gradient and high overpressure. Overpressure associated with nonequilibrium compaction mainly occurs at depths more than 2800 m at the basin center and more than 4000 m at the basin margin because the shallow-bu...

The last 3.85 Gyr of Earth history have been divided into five stages. During stage 1 (3.85-2.45 Gyr ago (Ga)) the atmosphere was largely or entirely anoxic, as were the oceans, with the possible exception of oxygen oases in the shallow oceans. During stage 2 (2.45-1.85 Ga) atmospheric oxygen levels rose to values estimated to have been between 0.02 and 0.04 atm. The shallow oceans became mildl...

A general method for the derivation of asymptotic nonlinear shallow water and deep water models is presented. Starting from a general dimensionless version of the water-wave equations, we reduce the problem to a system of two equations on the surface elevation and the velocity potential at the free surface. These equations involve a Dirichlet-Neumann operator and we show that all the asymptotic...

The use of visuals (e.g., videos, animations) to promote learning has been of great interest to researchers and educators. A key challenge is to determine the extent to which cognitively-based, instructional supports (e.g., prompts, feedback) can promote deeper understanding when students learn with visual materials. In this research, we explored the effects of deep vs. shallow questions on ind...

Vapor-deposited Alq3 is used as the green emitting layer in a class of organic light-emitting diodes. In this paper, the time dependence of the ̄uorescence from thin Alq3 ®lms has been studied by means of the femtosecond ̄uorescence upconversion technique. From the temporally resolved emission spectra, obtained after spectral reconstruction, the existence of di€erent emissive sites in the Alq3 ...