A strategic framework to eco-regionalize Ontario.

Ontario is a spatially heterogenous province. Natural resource policies and management plans must therefore address and account for this heterogeneity.An eco-regionalization scheme must possess certain minimum criteria to be effective. These criteria are: 1) an explicit explanation of spatial and temporal scales and variation; 2) a hierarchical construct of eco-regional domains; 3) an explicit quantitative description of the eco-regional domains; and, most importantly, 4) an ability to test a given eco-regional scheme as a hypothesis.This paper describes a hierarchical eco-regional framework (HEF) currently being constructed for Ontario. HEF is based on the scale-specific expression of ecological domain structure (geoclimatological parameters) and function (primary productivity). The approach relies on current advances in ecological hierarchy theory, remote sensing techniques, GIS methodologies, and statistical techniques. When completed, HEF will serve as a hypothesis which may be tested and validated at several different spatial scales.

Dry beveling of micropipette electrodes.

Beveling or otherwise modifying the tips of micropipettes has been found to improve their performance. Although some success has been reported, especially with wet beveling methods, problems and uncertainties are significant. In this paper we describe both manual and automated dry beveling systems which use a bevel table and bevel plate similar to those in wet beveling schemes. However, instead of using electrode impedance changes as a guide to the shape and size of electrode tips, we monitor beveling with a piezoelectric crystal which detects the minute vibrations of the electrode as the tip scrapes the bevel plate. The filtered output of the crystal indicates the progress of the grinding operation and allows the process to be controlled. Precise control of electrode tip movement is accomplished through use of a Kopf model 607B motorized hydraulic microdrive, amenable to both automated and manual control. The whole process can be followed by non-destructive electron microscope (E.M.) examination of electrode tips. Dry beveling combined with E.M. examination of electrode tips allows a much more precise determination of optimal electrode tip size and shape than is at present possible with wet beveling.

Non-destructive electron microscopic examination with rotation of beveled micropipette electrode tips.

A method is described for non-destructive transmissive mode viewing of micropipette electrodes on an electron microscope by modifying the series 100 stage of a Cambridge S4 scanning electron microscope. The modified stage allows electrode rotation and movement in both the X and Y directions without altering the external controls of the electron microscope. We have used this technique to select dry beveled electrodes. The technique allows precise determination of optimal micropipette electrode tip size and shape for a specific purpose.