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PubMed2006

Uneven environmental management: a Canadian perspective.

Advocates of community-based approaches to environmental management argue that by respecting local circumstances, skills, and concerns we may improve the prospects of achieving environmental sustainability; yet, within nation states such as Canada, environmental conditions, management and enforcement costs and capabilities, and power differentials within and among civic and public sectors may result in a highly differentiated capacity for environmental management across different localities and regions. This article draws on insights of political ecology to 1) create a conceptual framework that identifies key elements shaping regional environmental management regimes and to 2) undertake a comparative analysis to assess how elements interact to generate uneven management outcomes. I compare experiences of two Canadian biosphere reserves designated in 2000: Clayoquot Sound, BC; and Redberry Lake, SK. Analysis reveals that differences in governance and institutional capacities in the biosphere reserves are key to explaining uneven local outcomes. Where the public and civic sectors are strong, a robust and publicly vetted form of management will emerge. Where these sectors are weak and land is held as private property, environmental nongovernmental organizations can set the type and level of management, to the exclusion of effective civic and state involvement. This result may improve environmental sustainability but hinder social sustainability of a management regime and raises questions about the efficacy of community-based management.

Canada↗
PubMed1992

Interface problems between material recycling systems and plants.

A most important problem to creating a CELSS system to be used in space, for example, for a Lunar Base or Manned Mars mission, seems to be how to design and operate the various material recycling systems to be used on the missions. Recent studies of a Lunar Base habitat have identified examples of CELSS configurations to be used for the Plant Cultivation Module. Material recycling subsystems to be installed in the Plant Cultivation Modules are proposed to consist of various sub-systems, such as dehumidifiers, oxygen separation systems, catalytic wet oxidation systems, nitrogen adjusting systems, including tanks, and so on. The required performances of such various material recycling subsystems are determined based on precise metabolic data of derived from the various species of plants to be selected and investigated. The plant metabolic data, except that for wheat and potato, has not been fully collected at the present time. Therefore, much additional plant cultivation data is required to determine the performances of each material recycling subsystem introduced in Plant Cultivation Modules.

Carbon Dioxide↗
PubMed1974

Structure of wet specimens in electron microscopy. Improved environmental chambers make it possible to examine wet specimens easily.

Several recent technological advances have increased the practicality and usefulness of the technique of electron microscopy of wet objects. (i) There have been gains in the effective penetration of high-voltage microscopes, scanning transmission microscopes, and high-voltage scanning microscopes. The extra effective penetration gives more scope for obtaining good images through film windows, gas, and liquid layers. (ii) Improved methods of obtaining contrast are available (especially dark field and inelastic filtering) that often make it possible to obtain sufficient contrast with wet unstained objects. (iii) Improved environmental chamber design makes it possible to insert and examine wet specimens as easily as dry specimens. The ultimate achievable resolution for wet objects in an environmental chamber will gradually become clear experimentally. Resolution is mainly a function of gas path, liquid and wet specimen thickness, specimen stage stability, acceleration voltage, and image mode (fixed or scanning beam) (13). Much depends on the development of the technique for controlling the thickness of extraneous water film around wet objects or the technique for depositing wet objects onto dry, hydrophobic support films. Although some loss of resolution due to water or gas scattering will always occur, an effective gain is anticipated in preserving the shape of individual molecules and preventing the partial collapse that usually occurs on drying or negative staining. The most basic question for biological electron microscopy is probably whether any living functions of cells can be observed so that the capabilities of the phase contrast and interference light microscopes can be extended. Investigators are now rapidly approaching a final answer to this question. The two limiting factors are (i) maintaining cell motility in spread cells immersed in thin layers of media and (ii) reducing beam radiation damage to an acceptable level. The use of sensitive emulsions and image intensifiers can bring the observation dose below that required to stop cell motility. Use of a timed, pulsed deflector system enables sufficiently short exposures to be obtained to eliminate blurring due to Brownian motion. Environmental chambers have enhanced the possibilities of electron diffraction analysis of minute crystals and ordered biological structures. High-resolution electron diffraction patterns (especially kinematic) of protein crystals can only be obtained in a wet environment. Hence, it may now be possible to obtain undistorted images of protein molecules. Moreover, by subjecting diffraction patterns to image-iterative techniques (56), it will be possible to phase the electron diffraction patterns to give a calculated image with a higher resolution than that which can be produced by electron microscope objective lenses. Environmental chambers offer exciting prospects for the determination of water structure and water and ice nucleation (atmospheric science). Nucleation data near the molecular level have been badly needed for some time. The application of environmental chambers in industrial chemistry, for example, in studies of polymerization, catalysis, and corrosion, are awaiting exploration. They offer an unusual approach to measurements of reaction kinetics through images that should be both sensitive and rapid.

Animals↗
PubMed2004

The psychosocial work environment and musculoskeletal disorders: design of a comprehensive interviewer-administered questionnaire.

BACKGROUND: Psychosocial working conditions are likely to contribute to work-related musculoskeletal disorders (WRMSDs), but a lack of standardized measurement tools reflects both the theoretical and methodological limitations of current research. METHODS: An interdisciplinary team including biomedical, behavioral, and social science researchers used an iterative process to adapt existing instruments for an interviewer-administered questionnaire assessing psychosocial workplace exposure related to musculoskeletal disorders. RESULTS: The resulting questionnaire included measures of psychosocial workplace factors based on two theoretical models (the demand-control-support and the effort-reward imbalance models), supplemented by the additional constructs of "emotional demands," and "experiences of discrimination." Other psychosocial and physical measures selected for questionnaire inclusion address physical workload, sociodemographic and anthropometric characteristics, social relations and life events, health behaviors, and physical and psychological health. CONCLUSION: Using an interdisciplinary approach facilitated the development of a comprehensive questionnaire inclusive of key measures of psychosocial factors that may play a role in the complex mechanisms leading to WRMSDs.

Humans↗
PubMed2007

Development of an ecologic marine classification in the new zealand region.

We describe here the development of an ecosystem classification designed to underpin the conservation management of marine environments in the New Zealand region. The classification was defined using multivariate classification using explicit environmental layers chosen for their role in driving spatial variation in biologic patterns: depth, mean annual solar radiation, winter sea surface temperature, annual amplitude of sea surface temperature, spatial gradient of sea surface temperature, summer sea surface temperature anomaly, mean wave-induced orbital velocity at the seabed, tidal current velocity, and seabed slope. All variables were derived as gridded data layers at a resolution of 1 km. Variables were selected by assessing their degree of correlation with biologic distributions using separate data sets for demersal fish, benthic invertebrates, and chlorophyll-a. We developed a tuning procedure based on the Mantel test to refine the classification's discrimination of variation in biologic character. This was achieved by increasing the weighting of variables that play a dominant role and/or by transforming variables where this increased their correlation with biologic differences. We assessed the classification's ability to discriminate biologic variation using analysis of similarity. This indicated that the discrimination of biologic differences generally increased with increasing classification detail and varied for different taxonomic groups. Advantages of using a numeric approach compared with geographic-based (regionalisation) approaches include better representation of spatial patterns of variation and the ability to apply the classification at widely varying levels of detail. We expect this classification to provide a useful framework for a range of management applications, including providing frameworks for environmental monitoring and reporting and identifying representative areas for conservation.

Classification↗
PubMed1993

Mutations designed to modify the environment of the primary electron donor of the reaction center from Rhodobacter sphaeroides: phenylalanine to leucine at L167 and histidine to phenylalanine at L168.

Two mutations, L168 His to Phe and L167 Phe to Leu, were made in residues near the primary electron donor, a bacteriochlorophyll dimer, of the reaction center from Rhodobacter sphaeroides. Blue shifts of 10-15 nm in the 865-nm band of the donor were observed in the optical absorption spectra of both of the mutant reaction centers. The rate of initial electron transfer was determined by measurement of the kinetics of the decay of the excited state of the donor, and the rate of charge recombination was determined by measurement of the recovery of the bleaching of the donor. The initial electron transfer time constant and the charge recombination time constant were determined to be 3.6 ps and 220 ms, respectively, in the L168 His to Phe mutant and 5.0 ps and 85 ms in the L167 Phe to Leu mutant, compared to 3.8 ps and 100 ms measured for the wild type. The oxidation potential of the donor measured by oxidation-reduction titrations was found to decrease by 80 mV in the L168 His to Phe mutant and increase by 25 mV in the L167 Phe to Leu mutant. Time-resolved fluorescence decay measurements indicated that the change in the oxidation potential of the donor in the L168 His to Phe mutant resulted in a change in the energies of the charge-separated states. The results show that an increase in the driving force does not increase the rate of the initial electron transfer reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Histidine↗
PubMed2005

Optical design in beam steering environments with emphasis on laser transmission measurements.

Optical sensors applied to practical devices often encounter beam steering: the wander and/or diffusion of laser light. Here we provide a framework for minimizing the sensitivity of transmission-based sensors to beam steering without quantitative prediction of the severity of the beam-steering field. Typical goals are increased transmission and/or minimized fluctuations in transmission; such features can improve optical sensor performance (e.g., improved signal-to-noise ratio, response time, or spectral resolution). In our framework, we introduce a parameter for characterizing beam-steering severity. We then compare two approaches for absorption spectroscopy and show that the preferred approach depends on the total spectral range monitored, the spectral resolution desired, and the severity of the beam steering.

Journal Article↗