Showing papers by "University of Saskatchewan published in 2000"
TL;DR: In this article, a simple model is constructed to predict the size dependence of the effective stiffness of the structural element, and the important length scale in the problem is identified to be the ratio of the surface elastic modulus to the elastic modulation of the bulk.
Abstract: Effective stiffness properties (D) of nanosized structural elements such as plates and beams differ from those predicted by standard continuum mechanics (Dc). These differences (D-Dc)/Dc depend on the size of the structural element. A simple model is constructed to predict this size dependence of the effective properties. The important length scale in the problem is identified to be the ratio of the surface elastic modulus to the elastic modulus of the bulk. In general, the non-dimensional difference in the elastic properties from continuum predictions (D-Dc)/Dc is found to scale as αS/Eh, where α is a constant which depends on the geometry of the structural element considered, S is a surface elastic constant, E is a bulk elastic modulus and h a length defining the size of the structural element. Thus, the quantity S/E is identified as a material length scale for elasticity of nanosized structures. The model is compared with direct atomistic simulations of nanoscale structures using the embedded atom method for FCC Al and the Stillinger-Weber model of Si. Excellent agreement between the simulations and the model is found.
1,648 citations
TL;DR: The purpose of this report is to represent the progress in analytical methodologies over the last decade and assessment of the major agreements and issues discussed with regard to small molecules at both the conference and the workshop.
Abstract: This report is a synthesis of (1) the earlier conference on Analytical Methods Validation−Bioavailability, Bioequivalence and Pharmacokinetic Studies (Conference held in Arlington, VA, December 3–5, 1990 and the report published in Pharmaceutical Research, 9: 588-592, 1992) and (2) the workshop on “Bioanalytical Methods Validation—A Revisit with a Decade of Progress,” (Workshop held in Arlington, VA, January 12–14, 2000), sponsored by the American Association of Pharmaceutical Scientists and the U. S. Food and Drug Administration. The bioanalytical method validation workshop of January 12–14, 2000 was directed towards small molecules. A separate workshop was held in March 1–3, 2000 to discuss validation principles for macromolecules. The purpose of this report is to represent the progress in analytical methodologies over the last decade and assessment of the major agreements and issues discussed with regard to small molecules at both the conference and the workshop. The report is also intended to provide guiding principles for validation of bioanalytical methods employed in support of bioavailability, bioequivalence, and pharmacokinetic studies in man and in animals.
1,588 citations
TL;DR: This paper conducted a study on language learning orientations using self-determination theory (SDT) and found that travel, friendship, knowledge, and knowledge orientations were correlated with hypothesized antecedents and consequences in a manner similar to intrinsic motivation and identified regulation.
Abstract: The data for this study were collected in my first year of graduate school for a term paper for a course I was taking from Luc Pelletier. When I began graduate school, Luc also started at the University of Ottawa as a new faculty member, and he taught a course in motivation. I had worked with Richard Clement for a couple of years already as an honors student and as a research assistant and had conducted research on orientations and motivation under his supervision as part of my honors thesis project. Luc was very interested in self-determination theory (SDT) and had worked with Bob Vallerand on an instrument to assess academic motivation from this perspective. Luc and I decided to carry out a study on language learning orientations using SDT and enlisted Richard's and Bob's involvement in the project. As a bilingual institution where all students were required to demonstrate competence in their second language (L2), whether French or English, the University of Ottawa was an ideal setting for this type of research.
The project was a first examination of SDT in the language learning context, and to the best of my knowledge it was the only, or at least one of the very few, empirical investigations of intrinsic and extrinsic motivation in the area. It involved the development of a valid and reliable instrument to assess the different subtypes of intrinsic and extrinsic motivation. It also explored the link between these motivational subtypes and various orientations to language learning that had been identified by Clement and Kruidenier (1983), including the travel, friendship, knowledge, and instrumental orientations. The results showed that the instrumental orientation and the SDT external regulation orientation were strongly correlated, and that the travel, friendship, and knowledge orientations were quite highly intercorrelated with identified regulation and intrinsic motivation. Moreover, the instrumental and external regulation orientation scales correlated in similar ways with the hypothesized antecedents of perceived autonomy and competence and the hypothesized consequences of intention to pursue L2 study and anxiety. In addition, the travel, friendship, and knowledge orientations were correlated with the hypothesized antecedents and consequences in a manner similar to intrinsic motivation and identified regulation. These results suggested that Clement and Kruidenier's 4 orientations may be tapping a similar construct as the SDT orientations. My only regret with this study is that I did not include a scale to measure the integrative orientation (Gardner, 1985) to determine its relation with the SDT subtypes. This issue would have to wait until a later study to be addressed.
The results of this initial investigation encouraged me to pursue research integrating SDT with other theoretical frameworks of language learning motivation. I believe that the SDT framework has several advantages over some other formulations of learner orientations. SDT offers a parsimonious, internally consistent framework for systematically describing many different orientations in a comprehensive manner. It also offers considerable explanatory power for understanding why certain orientations are better predictors of relevant language learning variables (e.g., effort, persistence, attitudes) than others. Also, by invoking the psychological mechanisms of perceived autonomy, competence, and relatedness, it can account for why certain orientations are evident in some learners and not in others. Moreover, the framework is empirically testable and indeed has stood up well under empirical scrutiny in our studies. Its clear predictions may also be particularly valuable in applying the theory in language teaching and program development. [The present article first appeared in Language Learning, 50 (1), 2000, 57–85]
1,092 citations
TL;DR: In this paper, the authors employed satellite radio-telemetry to examine patterns of habitat selection by female woodland caribou in central Saskatchewan at both coarse (seasonal range) and fine (daily area) scales.
Abstract: Habitat selection is a hierarchical process that may yield various patterns depending on the scales of investigation. We employed satellite radio-telemetry to examine patterns of habitat selection by female woodland caribou in central Saskatchewan at both coarse (seasonal range) and fine (daily area) scales. At each scale, we converted spatial data describing compositions of available and used habitat to standardised resource selection indices and examined them with multivariate analyses of variance. Seasonal ranges generally showed preferential inclusion of peatlands and black spruce dominated stands relative to recently disturbed stands and early seral stage forests. In all populations, caribou preferred peatlands and black spruce forests to all other habitat types at the daily area scale. In general, these patterns may reveal the effective avoidance of wolves, the primary factor limiting caribou throughout the boreal forest. In three populations where seasonal ranges showed the selective inclusion of either young jack pine stands or clearcuts along with peatlands and black spruce forests, we found a relative avoidance of the clearcuts and young jack pine stands at the daily area scale. As all caribou populations in the area are thought to be relics of a once more continuous distribution, the seasonal range selection by animals in disturbed areas may better describe historic rather than current habitat selection. We found inter-annual variation in selection at the coarser spatial scale in one population, and inter-seasonal variation in selection at the finer spatial scale in three populations, indicating that the relative grains of the spatial and temporal scales coincide. We were better able to explain the seasonal variations in finer scale selection by considering available forage, a factor less likely than predation to limit woodland caribou populations. The data agree with the theory that the spatial and temporal hierarchy of habitat selection reflects the hierarchy of factors potentially limiting individual fitness.
513 citations
TL;DR: By generating other transgenic lines in which the hsp70 promoter regulates genes of interest, it should be possible to examine the in vivo activity of the gene products by laser-inducing specific cells to express them in zebrafish embryos.
Abstract: Over the past few years, a number of studies have described the generation of transgenic lines of zebrafish in which expression of reporters was driven by a variety of promoters. These lines opened up the real possibility that transgenics could be used to complement the genetic analysis of zebrafish development. Transgenic lines in which the expression of genes can be regulated both in space and time would be especially useful. Therefore, we have cloned the zebrafish promoter for the inducible hsp70 gene and made stable transgenic lines of zebrafish that express the reporter green fluorescent protein gene under the control of a hsp70 promoter. At normal temperatures, green fluorescent protein is not detectable in transgenic embryos with the exception of the lens, but is robustly expressed throughout the embryo following an increase in ambient temperature. Furthermore, we have taken advantage of the accessibility and optical clarity of the embryos to express green fluorescent protein in individual cells by focussing a sublethal laser microbeam onto them. The targeted cells appear to develop normally: cells migrate normally, neurons project axons that follow normal pathways, and progenitor cells divide and give rise to normal progeny cells. By generating other transgenic lines in which the hsp70 promoter regulates genes of interest, it should be possible to examine the in vivo activity of the gene products by laser-inducing specific cells to express them in zebrafish embryos. As a first test, we laser-induced single muscle cells to make zebrafish Sema3A1, a semaphorin that is repulsive for specific growth cones, in a hsp70-sema3A1 transgenic line of zebrafish and found that extension by the motor axons was retarded by the induced muscle.
451 citations
TL;DR: It is concluded that these potassium movements are not used as a signal system, only as a homeostatic feedback mechanisms, and a genuine signal system involving glial elements exists--but it is based on calcium waves.
437 citations
TL;DR: It is estimated that 26% of adult calcium is laid down during the 2 adolescent years of peak skeletal growth, which requires high accretion rates of calcium, achieved in part by increased retention efficiency of dietary calcium.
Abstract: The primary purpose of this study was to estimate the magnitude and variability of peak calcium accretion rates in the skeletons of healthy white adolescents. Total-body bone mineral content (BMC) was measured annually on six occasions by dual-energy X-ray absorptiometry (DXA; Hologic 2000, array mode), a BMC velocity curve was generated for each child by a cubic spline fit, and peak accretion rates were determined. Anthropometric measures were collected every 6 months and a 24-h dietary recall was recorded two to three times per year. Of the 113 boys and 115 girls initially enrolled in the study, 60 boys and 53 girls who had peak height velocity (PHV) and peak BMC velocity values were used in this longitudinal analysis. When the individual BMC velocity curves were aligned on the age of peak bone mineral velocity, the resulting mean peak bone mineral accrual rate was 407 g/year for boys (SD, 92 g/year; range, 226-651 g/year) and 322 g/year for girls (SD, 66 g/year; range, 194-520 g/year). Using 32.2% as the fraction of calcium in bone mineral, as determined by neutron activation analysis (Ellis et al., J Bone Miner Res 1996;11:843-848), these corresponded to peak calcium accretion rates of 359 mg/day for boys (81 mg/day; 199-574 mg/day) and 284 mg/day for girls (58 mg/day; 171-459 mg/day). These longitudinal results are 27-34% higher than our previous cross-sectional analysis in which we reported mean values of 282 mg/day for boys and 212 mg/day for girls (Martin et al., Am J Clin Nutr 1997;66:611-615). Mean age of peak calcium accretion was 14.0 years for the boys (1.0 years; 12.0-15.9 years), and 12.5 years for the girls (0.9 years; 10.5-14.6 years). Dietary calcium intake, determined as the mean of all assessments up to the age of peak accretion was 1140 mg/day (SD, 392 mg/day) for boys and 1113 mg/day (SD, 378 mg/day) for girls. We estimate that 26% of adult calcium is laid down during the 2 adolescent years of peak skeletal growth. This period of rapid growth requires high accretion rates of calcium, achieved in part by increased retention efficiency of dietary calcium.
414 citations
TL;DR: In this paper, the x-ray sensitivity of a high-resistivity photoconductor sandwiched between two parallel plate electrodes and operating under a constant field is analyzed by considering charge carrier generation that follows the xray photon absorption profile and taking into account both electron and hole trapping phenomena but neglecting recombination, bulk space charge and diffusion effects.
Abstract: The x-ray sensitivity of a high-resistivity photoconductor sandwiched between two parallel plate electrodes and operating under a constant field is analysed by considering charge carrier generation that follows the x-ray photon absorption profile and taking into account both electron and hole trapping phenomena but neglecting recombination, bulk space charge and diffusion effects. The amount of collected charge in the external circuit due to distributed generation of electrons and holes through the detector is calculated by integrating the Hecht collection efficiency with Ramo's theorem across the sample thickness. The results of the model allow the x-ray sensitivity to be calculated as a function of the applied field, detector thickness and electron and hole ranges (µτ), given the field and energy dependence of the electron and hole pair creation energy, W±, and the energy spectrum of incident x-ray radiation. The sensitivity model was applied to stabilized a-Se that is currently used as a successful x-ray photoconductor in the recently developed flat panel x-ray image detectors. Recent free electron-hole pair creation energy versus electric field data at room temperature and appropriate electron and hole drift mobilities were used to calculate the sensitivity for monoenergetic x-rays at 20 and at 60 keV. For the 20 keV radiation, it was shown that a typical detector thickness of 200 µm (4 × attenuation depth at 20 keV) with currently attainable electron and hole trapping parameters in a-Se was operating optimally, the sensitivity of which can only be increased by further increasing the applied field. With the receiving electrode positively biased, the sensitivity was much more dependent on the hole lifetime than electron lifetime. The absence of hole transport results in a reduction in sensitivity by a factor of about 4.4, whereas the absence of electron transport results in a sensitivity degradation of only 22%. The ratio of hole trapping limited sensitivity to electron trapping limited sensitivity is about 0.3. For a detector of thickness 200 µm operating at 10 V µm-1, the maximum sensitivity is about 220 pC cm-2 mR-1, and this sensitivity degrades by more than 10% when either the electron lifetime falls below ~20 µs or the hole lifetime falls below ~5 µs. When the hole lifetime is very short so that the sensitivity is substantially reduced, the sensitivity versus thickness dependence at a given field exhibits a maximum (an optimal thickness) that is less than that for full absorption. In the case of 60 keV x-ray photons, it is more useful to examine the sensitivity as a function of detector thickness given the practical bias voltage limit. The sensitivity versus thickness behaviour for a given bias voltage exhibits a maximum, that is an optimal thickness, that is less than that for nearly full absorption. Electron lifetimes longer than ~200 µs and hole lifetimes longer than ~10 µs do not significantly affect the sensitivity.
330 citations
TL;DR: It is demonstrated that ICK1 acts as a CDK inhibitor in the plant, and the inhibition of cell division byICK1 expression has profound effects on plant growth and development, and it is suggested that alterations of plant organ shape can be achieved by restriction ofcell division.
Abstract: Summary
The plant CDK inhibitor ICK1 was identified previously from Arabidopis thaliana with its inhibitory activity characterized in vitro. ICK1 displayed several structural and functional features that are distinct from known animal CDK inhibitors. Despite the initial characterization, there is no information on the functions of any plant CDK inhibitor in plants. To gain insight into ICK1 functions in vivo and the role of cell division during plant growth and development, transgenic plants were generated expressing ICK1 driven by the cauliflower mosaic virus 35S promoter. In comparison to control plants, growth was significantly inhibited in transgenic 35S-ICK1 plants, with some plants weighing <10% of wild-type plants at the 3 week stage. Most organs of 35S-ICK1 plants were smaller. There were also modifications in plant morphology such as shape and serration of leaves and petals. The changes were so drastic that 35S-ICK1 plants with strong phenotype no longer resembled wild-type plants morphologically. Analyses showed that increased ICK1 expression resulted in reduced CDK activity and reduced the number of cells in these plants. Cells in 35S-ICK1 plants were larger than corresponding cells in control plants. These results demonstrate that ICK1 acts as a CDK inhibitor in the plant, and the inhibition of cell division by ICK1 expression has profound effects on plant growth and development. They also suggest that alterations of plant organ shape can be achieved by restriction of cell division.
310 citations
TL;DR: In this article, the peakon-antipeakon solution of the Camassa-Holm equation is expressed in terms of the orthogonal polynomials of the related classical moment problem.
308 citations
TL;DR: It is found that boys were more physically active than girls and had higher perceptions of sport competence and strength, and all PSPP scales were significantly correlated with physical activity in both boys and girls.
Abstract: The aim of this study was to determine the relationship between physical self-perceptions and physical activity in Canadian school children aged 10–14 years. The sample consisted of 220 boys and 246 girls in grades 5–8. Physical activity was assessed by 7-day recall using the Physical Activity Questionnaire for Older Children. Selfperceptions of physical conditioning, sports competence, strength, body appearance and general physical selfworth were measured by the Physical Self-Perception Profile (PSPP). We found that boys were more physically active than girls and had higher perceptions of sport competence and strength. All PSPP scales were significantly correlated with physical activity in both boys and girls. Structural equation modelling procedures found the hierarchical PSPP model provided a good fit to the observed data, with little evidence of diff erences between the sexes. Analysis of five alternative structural models of the relationship between the PSPP and physical activity found the most parsi...
TL;DR: In this paper, a case study of the US grains industry provides an illustration of the framework, which links drivers for change to product characteristics, which in turn affect transaction characteristics and transaction costs, thereby leading to a change in vertical co-ordination.
Abstract: Closer vertical co‐ordination of supply chains is becoming a prevalent feature in the agri‐food sectors of many countries. Presents a framework within which to analyse these changes. The framework links drivers for change to product characteristics, which in turn affect transaction characteristics and transaction costs, thereby leading to a change in vertical co‐ordination. A case study of the US grains industry provides an illustration of the framework. Implications for agricultural producers, producer groups and policy makers are discussed.
TL;DR: There are six distinct classes of gold deposits, each represented by metallogenic provinces, having 100's to >1000 tonne gold production as mentioned in this paper : orogenic gold; (2) Carlin and Carlin-like gold deposits; (3) epithermal gold-silver deposits; copper-gold porphyry deposits; iron-oxide copper-Gold deposits; and (6) gold-rich volcanic hosted massive sulfide (VMS) to sedimentary exhalative (SEDEX) deposits.
Abstract: There are six distinct classes of gold deposits, each represented by metallogenic provinces, having 100's to >1000 tonne gold production. The deposit classes are: (1) orogenic gold; (2) Carlin and Carlin-like gold deposits; (3) epithermal gold-silver deposits; (4) copper-gold porphyry deposits; (5) iron-oxide copper-gold deposits; and (6) gold-rich volcanic hosted massive sulfide (VMS) to sedimentary exhalative (SEDEX) deposits. This classification is based on ore and alteration mineral assemblages; ore and alteration metal budgets; ore fluid pressure(s) and compositions; crustal depth or depth ranges of formation; relationship to structures and/or magmatic intrusions at a variety of scales; and relationship to the P-T-t evolution of the host terrane. These classes reflect distinct geodynamic settings. Orogenic gold deposits are generated at mid-crustal (4–16 km) levels proximal to terrane boundaries, in transpressional subduction-accretion complexes of Cordilleran style orogenic belts; other orogenic gold provinces form inboard, by delamination of mantle lithosphere, or plume impingement. Carlin and Carlin-like gold deposits develop at shallow crustal levels (<4 km) in extensional convergent margin continental arcs or back arcs; some provinces may involve asthenosphere plume impingement on the base of the lithosphere. Epithermal gold and copper-gold porphyry deposits are sited at shallow crustal levels in continental margin or intraoceanic arcs. Iron oxide copper-gold deposits form at mid to shallow crustal levels; they are associated with extensional intracratonic anorogenic magmatism. Proterozoic examples are sited at the transition from thick refractory Archean mantle lithosphere to thinner Proterozoic mantle lithosphere. Gold-rich VMS deposits are hydrothermal accumulations on or near the seafloor in continental or intraoceanic back arcs. The compressional tectonics of orogenic gold deposits is generated by terrane accretion; high heat flow stems from crustal thickening, delamination of overthickened mantle lithosphere inducing advection of hot asthenosphere, or asthenosphere plume impingement. Ore fluids advect at lithostatic pressures. The extensional settings of Carlin, epithermal, and copper-gold porphyry deposits result from slab rollback driven by negative buoyancy of the subducting plate, and associated induced convection in asthenosphere below the over-riding lithospheric plate. Extension thins the lithosphere, advecting asthenosphere heat, promotes advection of mantle lithosphere and crustal magmas to shallow crustal levels, and enhances hydraulic conductivity. Siting of some copper-gold porphyry deposits is controlled by arc parallel or orthogonal structures that in turn reflect deflections or windows in the slab. Ore fluids in Carlin and epithermal deposits were at near hydrostatic pressures, with unconstrained magmatic fluid input, whereas ore fluids generating porphyry copper-gold deposits were initially magmatic and lithostatic, evolving to hydrostatic pressures. Fertilization of previously depleted sub-arc mantle lithosphere by fluids or melts from the subducting plate, or incompatible element enriched asthenosphere plumes, is likely a factor in generation of these gold deposits. Iron oxide copper-gold deposits involve prior fertilization of Archean mantle lithosphere by incompatible element enriched asthenospheric plume liquids, and subsequent intracontinental anorogenic magmatism driven by decompressional extension from far-field plate forces. Halogen rich mantle lithosphere and crustal magmas likely are the causative intrusions for the deposits, with a deep crustal proximal to shallow crustal distal association. Gold-rich VMS deposits develop in extensional geodynamic settings, where thinned lithosphere extension drives high heat flow and enhanced hydraulic conductivity, as for epithermal deposits. Ore fluids induced hydrostatic convection of modified seawater, with unconstrained magmatic input. Some gold-rich VMS deposits with an epithermal metal budget may be submarine counterparts of terrestrial epithermal gold deposits. Real time analogs for all of these gold deposit classes are known in the geodynamic settings described, excepting iron oxide copper-gold deposits.
TL;DR: Results suggest that the metabolites of SDG have antioxidant activity, and the antioxidant activity was highest with SECO and ED and lowest with vitamin E.
Abstract: Secoisolariciresinol diglucoside (SDG), an antioxidant isolated from flaxseed, is metabolized to secoisolariciresinol (SECO), enterodiol (ED), and enterolactone (EL) in the body. The effectiveness of SDG in hypercholesterolemic atherosclerosis, diabetes, and endotoxic shock could be due to these metabolites. These metabolites may have antioxidant activity. However, the antioxidant activity of these metabolites is not known. The antioxidant activity of SECO, ED, and EL was investigated using chemiluminescence (CL) of zymosan-activated polymorphonuclear leukocytes (PMNLs) [PMNL-CL]. Other antioxidants (SDG and vitamin E) were also used for comparison. SDG, SECO, ED, EL, and vitamin E, each in the concentration of 0.5, 1.0, 2.5, 5.0 and 10.0 mg/ml, produced a concentration-dependent reduction in zymosan-activated PMNL-CL. SDG, SECO, ED, EL, and vitamin E, in the concentration of 2.5 mg/ml, produced a reduction of zymosan-activated PMNL-CL by 23.8%, 91.2%, 94.2%, 81.6% and 18.7%, respectively. Activated PMNLs produce reactive oxygen species and luminol-dependent CL reflects the amount of oxygen species generated from activated PMNLs. The reduction of PMNL-CL, therefore, reflects the antioxidant activity of the compounds studied. These results suggest that the metabolites of SDG have antioxidant activity. The antioxidant activity was highest with SECO and ED and lowest with vitamin E. The antioxidant potency of SECO, ED, EL, and SDG was 4.86, 5.02, 4.35, and 1.27 respectively, as compared to vitamin E. SECO, ED and EL are respectively 3.82, 3.95, and 3.43 more potent than SDG.
04 Jun 2000
TL;DR: A conceptual framework that articulates the mechanics of collaboration for shared-workspace groupware: the low level actions and interactions that must be carried out to complete a task in a shared manner is introduced.
Abstract: We introduce a conceptual framework that articulates the mechanics of collaboration for shared-workspace groupware: the low level actions and interactions that must be carried out to complete a task in a shared manner. These include communication, coordination, planning, monitoring, assistance, and protection. The framework also includes three general measures of these mechanics: effectiveness, efficiency, and satisfaction. The underlying idea of the framework is that some usability problems in groupware systems are not inherently tied to the social context in which the system is used but rather are a result of poor support for the basic activities of collaborative work in shared spaces. We believe that existing low-cost evaluation methods-heuristic evaluation, walkthroughs, user observations and questionnaires-can be modified to include this framework in a way that helps a groupware evaluator uncover these usability problems.
TL;DR: It is concluded that the monochlorobimane fluorescent method is sufficiently specific to reliably measure tissue GSH.
TL;DR: The biological results obtained revealed that the acetylhydrazones and semicarbazones afforded good protection against convulsions while the oxamoylHydrazones were significantly less active, suggesting that terminal electron-donating groups enhanced the hydrogen bonding capabilities and anticonvulsant properties of these molecules.
TL;DR: The magnitude and the duration of the haptoglobin response was found to correlate well with the severity of clinical signs (fever) and with the extent of lung consolidation while SAA responded most rapidly to infection.
TL;DR: To incorporate the possible findings of different patterns at different temporal and spatial scales, it is recommended to use a comparative approach to complement controlled manipulative experiments.
Abstract: Home range size characterizes the interplay between an organism and its environment Determinants of home range size can be intrinsic or extrinsic to the individual but all factors relate along a h
TL;DR: A conceptual model of spatial organization in vertebrates based upon changes in home range overlap with habitat quality based upon estimates of annual home ranges of adult females and densities for 30 populations of brown bears in North America shows consistency with behavioural theory predicting a nonlinear relationship between food availability and territoriality.
Abstract: We developed a conceptual model of spatial organization in vertebrates based upon changes in home range overlap with habitat quality. We tested the model using estimates of annual home ranges of adult females and densities for 30 populations of brown bears (Ursus arctos) in North America. We used seasonality as a surrogate of habitat quality, measured as the coefficient of variation among monthly actual evapotranspiration values for areas in which study populations were located. We calculated home range overlap for each population as the product of the average home range size for adult females and the estimated population density of adult females. Home range size varied positively with seasonality; however, home range overlap varied with seasonality in a nonlinear manner. Areas of low and high seasonality supported brown bears with considerable home range overlap, but areas of moderate seasonality supported brown bears with low home range overlap. These results are consistent with behavioural theory predicting a nonlinear relationship between food availability and territoriality.
TL;DR: In this paper, a yield surface is proposed to describe cellular solids, including foamed metals, and designed to be fitted to three experimental results: (1) the compressive stress-strain response (including densification), (2) the difference between the tensile and compressive yield points and (3) the degree of compressibility of the foam, as measured by the lateral expansion during a uniaxial stress compression test.
TL;DR: It was found that frequency formats were not generally associated with better performance than probability formats unless they were presented in a manner which facilitated construction of a set inclusion mental model, and it was demonstrated that the use of frequency information may promote biases in the weighting of information.
TL;DR: In this article, a summary of 630.0 nm emission observations made by the Cornell All-Sky Imager that have revealed an abundance of structure in the midlatitude thermosphere is presented.
Abstract: This paper presents a summary of 630.0 nm emission observations made by the Cornell All-Sky Imager that have revealed an abundance of structure in the midlatitude thermosphere. Some events were so bright that the weaker 557.7 nm thermospheric line was readily visible and produced sharper images because of the shorter excitation lifetime. Global Positioning System observations show that the airglow features are traveling ionospheric disturbances (TIDs). The remarkable feature of the data is the overwhelming tendency for these low-velocity TIDs to develop with a northwest to southeast orientation and to propagate in the southwest direction. Speeds ranged from 50 to 170 m/s, and wavelengths ranged from 50 to 500 km. The Perkins instability is investigated as a possible explanation for the structures. The linear theory, including both winds and electric fields, predicts a positive but small growth rate. However, the real part of the dispersion relation gives the wrong sign for the wave propagation. Furthermore, the growth rate seems too small to amplify a seed gravity wave significantly during one period of neutral gas oscillation. We conclude that this class of low-velocity TID is not yet explained theoretically.
TL;DR: Viscosity of barley flour slurries was affected by the content of soluble beta-glucans, beta-Glucanase activity, and molecular weight of beta- glucans.
Abstract: Total and soluble beta-glucan content and effects of various treatments of barley grain on extractability and molecular characteristics of soluble beta-glucan were studied. Four types of hulless barley (normal, high amylose, waxy, and zero amylose waxy) from 29 registered and experimental genotypes were analyzed. For each, moisture, protein, amylose, 100 kernel weight, starch, beta-glucan (total and soluble), beta-glucanase activity, and slurry viscosity were determined. Significant differences in total beta-glucan were observed among the groups, with average values of 7. 49%, 6.86%, 6.30%, and 4.38% for high amylose, waxy, zero amylose waxy, and normal barley, respectively. The extractability of beta-glucan in high amylose barley was relatively low (20.6-29.7%) compared to that in normal (29.8-44.3%), zero amylose waxy (34.0-52. 5%), and waxy (36.7-52.7%) barley genotypes. Viscosity of barley flour slurries was affected by the content of soluble beta-glucans, beta-glucanase activity, and molecular weight of beta-glucans. Hydrothermal treatments (autoclaving and steaming) of barley had no effect on extractability of beta-glucans, but prevented enzymic hydrolysis of beta-glucans, and thereby substantially improved their molecular weight. The addition of enzymes (protease and esterase) during extraction and/or physical treatments (sonication) increased extractability of beta-glucans from barley.
TL;DR: In this article, the authors describe the design and prototyping of a new high-performance actuation system that combines the benefits of conventional hydraulic systems and direct-drive electrical actuators, namely high torque/mass ratio and modularity.
Abstract: This paper describes the design and prototyping of a new high-performance actuation system that combines the benefits of conventional hydraulic systems and direct-drive electrical actuators, namely high torque/mass ratio and modularity. It is referred to as the electrohydraulic actuator (EHA) and results from the fusion of the above-mentioned technologies. The EHA is a unique device with its own characteristics and requires hydraulic components that are specifically tailored to its needs and requirements. Based on a mathematical model of the EHA, the requirements for its components are determined. These requirements are used as a basis for component selection, component modification, and design of a customized new symmetrical linear actuator. The analysis of the EHA presented is supported by experimental data and explains the extremely high level of performance attained by a prototype of the EHA.
TL;DR: This work reviews work reporting the chemical structures, synthesis, biosynthesis and metabolism of cruciferous phytoalexins, as well as their biological activity towards different microorganisms.
TL;DR: The objectives of the present study were to construct oat microsatellite-enriched libraries, to isolate micros satellite sequences and evaluate their level of polymorphism in Avena species and oat cultivars.
Abstract: Microsatellites have many desirable marker properties. There has been no report of the development and utilization of microsatellite markers in oat. The objectives of the present study were to construct oat microsatellite-enriched libraries, to isolate microsatellite sequences and evaluate their level of polymorphism in Avena species and oat cultivars. One hundred clones were isolated and sequenced from three oat microsatellite-libraries enriched for either (AC/TG)n, (AG/TC)n or (AAG/TTC)n repeats. Seventy eight clones contained microsatellites. A database search showed that 42% of the microsatellite flanking sequences shared significant homology with various repetitive elements. Alu and retrotransposon sequences were the two largest groups associated with the microsatellites. Forty four primer sets were used to amplify the DNA from 12 Avena species and 20 Avena sativa cultivars. Sixty two percent of the primers revealed polymorphism among the Avena species, but only 36% among the cultivars. In the cultivars, the microsatellites associated with repetitive elements were less polymorphic than those not associated with repetitive elements. Only 25% of the microsatellites associated with repetitive elements were polymorphic, while 46% of the microsatellites not associated with repetitive elements showed polymorphism in the cultivars. An average of four alleles with a polymorphism information content (PIC) of 0.57 per primer set was detected among the Avena species, and 3.8 alleles with a PIC of 0.55 among the cultivars. In addition, 54 barley microsatellite primers were tested in Avena species and 26% of the primers amplified microsatellites from oat. Using microsatellite polymorphisms, dendrograms were constructed showing phylogenetic relationships among Avena species and genetic relationships among oat cultivars.
TL;DR: This review will describe the recent advances that have been made in dermal and topical delivery as related to vaccines.
TL;DR: In this paper, the porewaters collected from eighteen piezometers installed between 3 and 91.4 m below ground in a thick till and clay-rich aquitard sequence located in southern Saskatchewan to investigate the distribution of, and controls on arsenic speciation in the sequence.