Don White

Trial-and-error and errorless training procedures were used to train two killer whales on a simple visual discrimination problem. Both whales demonstrated difficulties in solving the problem under trial-and-error training. The relative effectiveness of the two training procedures is evaluated.

The links between Earth and space exploration occur across a broad spectrum, from the use of satellite technology to support environmental monitoring and habitat protection to the study of extreme environments on Earth to prepare for the exploration of other planets. Taking the view that Earth and space exploration are part of a mutually beneficial continuum is in contrast to the more traditionally segregated view of these areas of activity. In its most polarized manifestation, space exploration is regarded as a waste of money, distracting from solving problems here at home, while environmental research is seen to be introspective, distracting from expansive visions of exploring the frontier of space. The Earth and Space Foundation was established in 1994 to help further mutually beneficial links by funding innovative field projects around the world that work at the broad interface between environmental and space sciences, thus encouraging the two communities to work together to solve the challenges facing society. This paper describes the work of the foundation and the philosophy behind its programmes.

Seismic reflection and electromagnetic (EM) data were acquired near Thompson, Manitoba, Canada, to map the subsurface extent of the Paleoproterozoic, nickel ore‐bearing Ospwagan Group. These data are supplemented by surface and borehole geology and by laboratory ...

Background Through the late 1980s, the Hong Kong Government was reviewing the management of its hospital services. It was finally decided that an autonomous Hospital Authority would be established with responsibility for all matters pertaining to the delivery of hospital medical ...

The underwater visual acuity of the killer whale (Orcinus orca) was estimated from its ability to resolve a variable gap between the lines of a two-line positive stimulus. The negative stimulus comprised two lines separated by a subthreshold gap. Two killer whales participated in the study, one during approximation of the visual resolution threshold, and a second during visual acuity testing. The underwater visual acuity of the killer whale was estimated to be 5.5 min of arc within a stimulus intensity range of 10–20 ft-c. The results of the study are interpreted as suggesting that killer whale vision is sufficiently well developed for it to be of considerable use in the guidance of behavior.

This experiment investigated the underwater visual acuity of one adult female Pacific white-sided dolphin (Lagenorhynchus obliquidens) by assessing its ability to discriminate between stimuli comprising one and two vertical lines presented simultaneously in a two-choice discrimination learning apparatus. The experiment was performed in two phases: an initial training phase in which a basic two-line vs. one-line discrimination was established, and a testing phase which utilized this discrimination learning in determination of visual acuity. Visual discrimination learning throughout the training phase, was unexpectedly slow and apparently highly problem-specific, despite the use of a sequence of problems designed to facilitate initial learning. During the testing phase of the study, eight two-line vs. one-line test problems, differing only in two-line gap widths were presented in a random sequence 100 times each during 10 daily sessions, at a minimal viewing distance of 45 cm. A standard psychophysical difference threshold criterion was applied to the performance data, yielding an estimate of underwater visual acuity of approximately 6′ of arc, a value roughly comparable to that for the cat in air. The results of the study are interpreted as suggesting that dolphin vision is probably sufficiently well-developed for it to be a behaviorally significant modality, but that vision may well play only a relatively minor or specialised role in the guidance of normal underwater behavior.

Carbon dioxide (CO 2 ) and hydrocarbons both occur as natural accumulations within the Earth and share an intertwined industrial history. Research in the 1950–1960s demonstrated that CO 2 had potential as a miscible agent for enhanced oil recovery (EOR), but ...

Carbon dioxide (CO 2 ) and hydrocarbons both occur as natural accumulations within the Earth and share an intertwined industrial history. Research in the 1950–1960s demonstrated that CO 2 had potential as a miscible agent for enhanced oil recovery (EOR), but ...

In previous work, we provided evidence from sap flow measurements that when root systems span soil layers of different moisture content, water is redistributed by roots in the direction of the difference in water potential. In addition to the phenomenon termed "hydraulic lift", where water is redistributed from depth to dry topsoil, the process of "hydraulic redistribution" includes downward transfer of water when the surface layers of soils with low permeability become wet after rainfall. In this paper, we support our previous findings with evidence from measurements of soil water and estimate the quantities of water transferred to depth following rain. Amounts of water stored at depth are not likely to be significant for drought avoidance by plants. However, downward transfer of water may be important to plant establishment and the reduction of waterlogging in certain soil types.

Forest managers now operate in an information-rich but increasingly challenging environment in which the competing demands of environmental stewardship and sustainable management must counter-balance the demands of increased production and profitability. Management support tools, in particular, decision support systems are essential aids in this operating environment. A dynamic forest growth model, CArbon BALAnce (CABALA), that links carbon, water and nitrogen flows through the atmosphere, trees and soil including soil organic matter is presented here as a central part of a silvicultural decision support system.The strong linkage between stand biomass allocation and external environmental conditions make CABALA a model suitable for exploring stand management options and the effects of factors such as frost and drought on growth.The model performance is verified extensively using fertiliser, spacing and thinning trials. Predictions of nitrogen mineralisation, light interception, plant water stress, and biomass allocation as well as stand growth and stand leaf area index are tested with observed data.