In response to drought stress the phytohormone ABA (abscisic acid) induces stomatal closure and, therein, activates guard cell anion channels in a calcium-dependent as well as-independent manner. Two key components of the ABA signaling pathway are the protein kinase OST1 (open stomata 1) and the protein phosphatase ABI1 (ABA insensitive 1). The recently identified guard cell anion channel SLAC1...

Guard cells generate reactive oxygen species (ROS) in response to abscisic acid (ABA), which leads to stomatal closing. The upstream steps of the ABA-induced ROS generation pathway remain largely unknown. In animal cells, ROS generation in neutrophils is activated by phosphatidylinositol 3-phosphate (PI3P). Stomatal guard cells contain PI3P and PI 3-kinase activity. In this study, we tested whe...

In this paper we study three related problems: (i) Given a fat polygon P , we show how to find a set G of points in P such that every point on the boundary of P sees at least one point of G. The set G is said to guard the boundary of P and its cardinality depends on the shape parameters of P . Fat polygons are often used to model more realistic inputs. (ii) Given k points that guard the boundar...

In the wireless localization problem, given a polygon P ⊂ R, we have to place guards and fix their angular range such that P can be described using these guards. The guards describe P if for every point pair p ∈ P and q / ∈ P , there is a guard that sees p but does not see q. We consider the analogous problem in 3D: given a polyhedron P ⊂ R, place guards—which now are polyhedral cones—that coll...

We appreciate the opportunity to testify on the Deepwater Capability Replacement Project, which was initiated by the Coast Guard to replace and modernize its aging fleet of over 90 cutters and 200 aircraft used beyond 50 miles from shore. This project, the largest acquisition ever attempted by the Coast Guard, will likely cost over $10 billion or more and will not be completed for 2 to 3 decade...

The base sledge microtome presents a hazard to the operator due to the length of blade that is exposed. Manipulation of the carriage requires hand movements close to the knife edge and serious lacerations may result. A simple, effective guard has been devised, suitable for knives which have screw holes for handles at both ends. It consists of two perspex end-pieces (Fig. I), attached to the kni...

A signi cant amount of software development is evolutionary, involving the modi cation of already existing programs. To a large extent, the modi ed programs produce the same results as the original program. This similarity between the original program and the development program is utilized by relative debugging. Relative debugging is a new concept that enables the user to compare the execution...

X-ray microanatysis has revealed that the sodium content of the stomatal guard cells of Aster tripolium remains much lower than that of other leaf cells when the plants are grown at high salinity. Large amounts of sodium did, in contrast, accumulate in epidermal and subsidiary cells, and particularly in the mesophyll tissue, suggesting that a mechanism exists to limit the extent of its entry in...

A 1985 graduate of the Coast Guard Academy, Captain Watts has served six sea tours with the Navy and Coast Guard, most recently commanding USCGC Steadfast (WMEC 623). A qualified Surface Warfare Officer and Cutterman, he holds advanced degrees from the Naval War College, Old Dominion University, American Military University, and the Naval Postgraduate School, and he is currently a doctoral cand...

With isolated epidermal strips of Vicia faba, the intensity of potassium-staining in the guard cells of stomata was calibrated against the uptake of radioactively labeled potassium. By using this calibration, the quantity of potassium that had accumulated in the guard cells, as stomata of leaves of Vicia open in the light, was estimated. Results support the hypothesis that in leaves, as well as...