The mechanism of the regulation of energy distribution between photosystems 1 and 2 in the cyanobacterium Synechococcus sp. strain PCC 7002 /

Cyanobacteria are able to regulate the distribution of absorbed light energy between photo systems 1 and 2 in response to light conditions. The mechanism of this regulation (the state transition) was investigated in the marine cyanobacterium Synechococcus sp. strain PCC 7002. Three cell types were used: the wild type, psaL mutant (deletion of a photo system 1 subunit thought to be involved in photo system 1 trimerization) and the apcD mutant (a deletion of a phycobilisome subunit thought to be responsible for energy transfer to photo system 1). Evidence from 77K fluorescence emission spectroscopy, room temperature fluorescence and absorption cross-section measurements were used to determine a model of energy distribution from the phycobilisome and chlorophyll antennas in state 1 and state 2. The data confirm that in state 1 the phycobilisome is primarily attached to PS2. In state 2, a portion of the phycobilisome absorbed light energy is redistributed to photo system 1. This energy is directly transferred to photo system 1 by one of the phycobilisome terminal emitters, the product of the apcD gene, rather than via the photo system 2 chlorophyll antenna by spillover (energy transfer between the photo system 2 and photo system 1 chlorophyll antenna). The data also show that energy absorbed by the photo system 2 chlorophyll antenna is redistributed to photo system 1 in state 2. This could occur in one of two ways; by spillover or in a way analogous to higher plants where a segment of the chlorophyll antenna is dissociated from photo system 2 and becomes part of the photo system 1 antenna. The presence of energy transfer between neighbouring photo system 2 antennae was determined at both the phycobilisome and chlorophyll level, in states 1 and 2. Increases in antenna absorption cross-section with increasing reaction center closure showed that there is energy transfer (connectivity) between photosystem 2 antennas. No significant difference was shown in the amount of connectivity under these four conditions.

Structural studies in the Southern Province, South of Sudbury, Ontario

Rocks correlated with the Hough Lake and Quirke Lake Groups of the Huronian Supergroup form part of a northeasterly trending corridor that separates 1750 Ma granitic intrusive rocks of the Chief Lake batholith from the 1850 Ma mafic intrusive rocks of the Sudbury Igneous Complex. This corridor is dissected by two major structural features; the Murray Fault Zone (MFZ) and the Long Lake Fault (LLF). Detailed structural mapping and microstructural analysis indicates that the LLF, which has juxtaposed Huronian rocks of different deformation style and metamorphism grade, was a more significant plane of dislocation than the MFZ. The sense of displacement along the LLF is high angle reverse in which rocks to the southeast have been raised relative to those in the northwest. South of the LLF Huronian rocks underwent ductile defonnation at amphibolite facies conditions. The strain was constrictional, defined by a triaxial strain ellipsoid in which X > Y > z. Calculations of a regional k value were approximately 1.3. Penetrative ductile defonnation resulted in the development of a preferred crystallographic orientation in quartz as well as the elongation of quartz grains to fonn a regional southeast-northwest trending, subvertical lineation. Similar lithologies north of the LLF underwent dominantly brittle deformation under greenschist facies conditions. Deformation north of the LLF is characterized by the thrusting of structural blocks to form angular discordances in bedding orientation which were previously interpreted as folds. Ductile deformation occurred between 1750 and 1238 Ma and is correlated with a regional period of south over north reverse faulting that effected much of the southern Sudbury region. Post dating the reverse faulting event was a period of sedimentation as a conglomerate unit was deposited on vertically bedded Huronian rocks. Rocks in the study area were intruded by both mafic and felsic dykes. The 1238 Ma mafic dykes appear to have been offset during a period of dextral strike slip displacement along the major fault'). Indirect evidence indicates that this event occurred after the thrusting at 950 to 1100 Ma associated with the Grenvillian Orogeny.

Quadtree representation and compression of spatial data

Spatial data representation and compression has become a focus issue in computer graphics and image processing applications. Quadtrees, as one of hierarchical data structures, basing on the principle of recursive decomposition of space, always offer a compact and efficient representation of an image. For a given image, the choice of quadtree root node plays an important role in its quadtree representation and final data compression. The goal of this thesis is to present a heuristic algorithm for finding a root node of a region quadtree, which is able to reduce the number of leaf nodes when compared with the standard quadtree decomposition. The empirical results indicate that, this proposed algorithm has quadtree representation and data compression improvement when in comparison with the traditional method.

Photograph - Dorothy Rungeling with Plane

A photograph of Dorothy Rungeling in front of a plane with the Mack Trucks and Buses logo. This photograph is from her personal scrapbooks, the page is labelled "1956 International Air Race Hamilton to Havana".

Photograph - Dorothy Rungeling's Fifth Plane

A photograph of Dorothy Rungeling inside her fifth and last plane (as written in her scrapbook). The airplane is described as a 1956 Beech Bonanza, 4 seat, retractable gear, 225 Continental engine.

Photograph - Dorothy Rungeling with Plane (Pacer 125), 1954

A photograph of Dorothy Rungeling in front of a plane (likely the second plane she owned). This photograph later appeared in the Canadian general interest magazine "Saturday Night". Mrs. Rungeling was featured in the "Canadian Personalities" section for her latest accomplishment, receiving her commercial pilot's licence.