Ryerson University

About: Ryerson University is a education organization based out in Toronto, Ontario, Canada. It is known for research contribution in the topics: Population & Poison control. The organization has 7671 authors who have published 20164 publications receiving 394976 citations. The organization is also known as: Ryerson Polytechnical Institute & Ryerson Institute of Technology.

A theoretical comparison of energy sources--microwave, ultrasound and laser--for interstitial thermal therapy.

Abstract: A number of heating sources are available for minimally invasive thermal therapy of tumours. The purpose of this work was to compare, theoretically, the heating characteristics of interstitial microwave, laser and ultrasound sources in three tissue sites: breast, brain and liver. Using a numerical method, the heating patterns, temperature profiles and expected volumes of thermal damage were calculated during standard treatment times with the condition that tissue temperatures were not permitted to rise above 100 degrees C (to ensure tissue vaporization did not occur). Ideal spherical and cylindrical applicators (200 microm and 800 microm radii respectively) were modelled for each energy source to demonstrate the relative importance of geometry and energy attenuation in determining heating and thermal damage profiles. The theoretical model included the effects of the collapse of perfusion due to heating. Heating patterns were less dependent on the energy source when small spherical applicators were modelled than for larger cylindrical applicators due to the very rapid geometrical decrease in energy with distance for the spherical applicators. For larger cylindrical applicators, the energy source was of greater importance. In this case, the energy source with the lowest attenuation coefficient was predicted to produce the largest volume of thermally coagulated tissue, in each tissue site.

A worldwide perspective on energy, environment and sustainable development

Abstract: Problems with energy supply and use are related not only to global warming, but also to such environmental concerns as air pollution, ozone depletion forest destruction and emission of radioactive substances. These issues must be taken into consideration simultaneously if humanity is to achieve a bright energy future with minimal environmental impacts. Much evidence exists which suggests that the future will be negatively impacted if humans keep degrading the environment. There is an intimate connection between energy, the environment and sustainable development. A society seeking sustainable development ideally must utilize only energy resources which cause no environmental impact (e.g. which release no emissions to the environment). However, since all energy resources lead to some environmental impact, it is reasonable to suggest that some (not all) of the concerns regarding the limitations imposed on sustainable development by environmental emissions and their negative impacts can be in part overcome through increased energy efficiency. A strong relation clearly exists between energy efficiency and environmental impact since, for the same services or products, less resource utilization and pollution is normally associated with higher efficiency processes. Anticipated patterns of future energy use and consequent environmental impact (focusing on acid precipitation, stratospheric ozone depletion and the greenhouse effect) are comprehensively discussed in this paper. Also, some solutions to current environmental issues in terms of energy conservation and renewable energy technologies are identified and some theoretical and practical limitations on increased energy efficiency are explained. The relations between energy and sustainable development, and between the environment and sustainable development, are described, and an illustrative example is presented. Throughout the paper several issues relating to energy, environment and sustainable development are examined from both current and future perspectives. Finally, several conclusions and recommendations are drawn which may be useful to energy scientists and engineers and policy makers. © 1998 John Wiley & Sons, Ltd.

The program for processing newly synthesized histones H3.1 and H4

Abstract: The mechanism by which newly synthesized histones are imported into the nucleus and deposited onto replicating chromatin alongside segregating nucleosomal counterparts is poorly understood, yet this program is expected to bear on the putative epigenetic nature of histone post-translational modifications. To define the events by which naive pre-deposition histones are imported into the nucleus, we biochemically purified and characterized the full gamut of histone H3.1-containing complexes from human cytoplasmic fractions and identified their associated histone post-translational modifications. Through reconstitution assays, biophysical analyses and live cell manipulations, we describe in detail this series of events, namely the assembly of H3-H4 dimers, the acetylation of histones by the HAT1 holoenzyme and the transfer of histones between chaperones that culminates with their karyopherin-mediated nuclear import. We further demonstrate the high degree of conservation for this pathway between higher and lower eukaryotes.