Showing papers by "University of Saskatchewan published in 2004"

Biofuel Cells Select for Microbial Consortia That Self-Mediate Electron Transfer

Abstract: Microbial fuel cells hold great promise as a sustainable biotechnological solution to future energy needs. Current efforts to improve the efficiency of such fuel cells are limited by the lack of knowledge about the microbial ecology of these systems. The purposes of this study were (i) to elucidate whether a bacterial community, either suspended or attached to an electrode, can evolve in a microbial fuel cell to bring about higher power output, and (ii) to identify species responsible for the electricity generation. Enrichment by repeated transfer of a bacterial consortium harvested from the anode compartment of a biofuel cell in which glucose was used increased the output from an initial level of 0.6 W m−2 of electrode surface to a maximal level of 4.31 W m−2 (664 mV, 30.9 mA) when plain graphite electrodes were used. This result was obtained with an average loading rate of 1 g of glucose liter−1 day−1 and corresponded to 81% efficiency for electron transfer from glucose to electricity. Cyclic voltammetry indicated that the enhanced microbial consortium had either membrane-bound or excreted redox components that were not initially detected in the community. Dominant species of the enhanced culture were identified by denaturing gradient gel electrophoresis and culturing. The community consisted mainly of facultative anaerobic bacteria, such as Alcaligenes faecalis and Enterococcus gallinarum, which are capable of hydrogen production. Pseudomonas aeruginosa and other Pseudomonas species were also isolated. For several isolates, electrochemical activity was mainly due to excreted redox mediators, and one of these mediators, pyocyanin produced by P. aeruginosa, could be characterized. Overall, the enrichment procedure, irrespective of whether only attached or suspended bacteria were examined, selected for organisms capable of mediating the electron transfer either by direct bacterial transfer or by excretion of redox components.

Further characterisation of the 91500 zircon crystal

Abstract: This paper reports the results from a second characterisation of the 91500 zircon, including data from electron probe microanalysis, laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS), secondary ion mass spectrometry (SIMS) and laser fluorination analyses. The focus of this initiative was to establish the suitability of this large single zircon crystal for calibrating in situ analyses of the rare earth elements and oxygen isotopes, as well as to provide working values for key geochemical systems. In addition to extensive testing of the chemical and structural homogeneity of this sample, the occurrence of banding in 91500 in both backscattered electron and cathodoluminescence images is described in detail. Blind intercomparison data reported by both LA-ICP-MS and SIMS laboratories indicate that only small systematic differences exist between the data sets provided by these two techniques. Furthermore, the use of NIST SRM 610 glass as the calibrant for SIMS analyses was found to introduce little or no systematic error into the results for zircon. Based on both laser fluorination and SIMS data, zircon 91500 seems to be very well suited for calibrating in situ oxygen isotopic analyses.

The Great Ordovician Biodiversification Event

Abstract: The Global Ordovician Biodiversification Event (GOBE) was undoubtedly one of the most significant evolutionary events in the history of the marine biosphere. A continuous increase in ichnodiversity occurs through the Ordovician in both shallow- and deep-marine environments. The earlier view that early Paleozoic deep-marine ichnofaunas are of low alpha diversity has been challenged by discoveries of moderately diverse associations. Interestingly, however, the increase in global ichnodiversity through the Ordovician is not paralleled by an increase in ichnodisparity of bioturbation structures. In fact, whereas global ichnodiversity in the Ordovician almost doubled Cambrian levels, Ordovician ichnodisparity of bioturbation structures is roughly similar to that resulting from the Cambrian explosion. Macroboring organisms also display significant evolutionary innovation and diversification in shallow-water hardgrounds and other carbonate substrates, resulting in the Ordovician Bioerosion Revolution. Along with this macroboring ichnodiversity and ichnodisparity increase is a significant rise in the rate of bioerosion in carbonate substrates. Ichnofaunal changes in lower-shoreface and offshore siliciclastic deposits through the Ordovician reveal faunal turnovers resulting from the evolutionary radiation. Lower Ordovician deposits tend to be dominated by abundant trilobite-produced trace fossils. Middle to Upper Ordovician shallow-marine ichnofaunas tend to show more varied behavioral patterns and trilobite trace fossils are rarely the dominant components. During the early Paleozoic, the tiering structure of ichnofaunas became more complex, as a result of both the addition of deeper tiers and of a wider variety of biogenic structures in previously occupied tiers. Infaunalization by deposit feeders in offshore siliciclastic environments was most likely diachronous, with the establishment of a mid-tier infauna first in Laurentia and Baltica, and only subsequently in Gondwana.

Analytical, Biochemical and Physicochemical Aspects of Starch Granule Size, with Emphasis on Small Granule Starches: A Review

Abstract: Granule size, size distribution and shape are among the most important morphologically distinguishing factors of starches from different origins. This article provides an overview of aspects related to starch granule size, including procedures for determining the size, the impact of granule size on the physicochemical characteristics of starch, and biosynthetic and environmental determinants of granule size. The focus is on small granule starches, including their isolation and current and potential utilization.

Grinding performance and physical properties of wheat and barley straws, corn stover and switchgrass

Abstract: Wheat and barley straws, corn stover and switchgrass at two moisture contents were ground using a hammer mill with three different screen sizes (3.2, 1.6 and 0.8 mm ). Energy required for grinding these materials was measured. Among the four materials, switchgrass had the highest specific energy consumption ( 27.6 kW h t −1 ), and corn stover had the least specific energy consumption ( 11.0 kW h t −1 ) at 3.2 mm screen size. Physical properties of grinds such as moisture content, geometric mean diameter of grind particles, particle size distribution, and bulk and particle densities were determined. Second- or third-order polynomial models were developed relating bulk and particle densities of grinds to geometric mean diameter within the range of 0.18– 1.43 mm . Switchgrass had the highest calorific value and the lowest ash content among the biomass species tested.

Bcl10 activates the NF-κB pathway through ubiquitination of NEMO

Abstract: The NF-κB family of transcription factors is activated in response to many stimuli, including pro-inflammatory cytokines, environmental stresses and, in the case of B and T lymphocytes, by antigenic stimulation1,2. Bcl10 is essential for NF-κB activation by T- and B-cell receptors. T and B lymphocytes from Bcl10-deficient mice fail to activate NF-κB in response to antigen-receptor stimulation and, as a consequence, are unable to proliferate3. Bcl10 overexpression is sufficient to activate NF-κB, a process that requires the NF-κB essential modulator NEMO (also known as IKK-γ), which is the regulatory subunit of the IκB kinase complex4. However, the cellular mechanism by which Bcl10 activates the NF-κB pathway remains unclear. Here we show that Bcl10 targets NEMO for lysine-63-linked ubiquitination. Notably, a mutant form of NEMO that cannot be ubiquitinated inhibited Bcl10-induced NF-κB activation. Paracaspase and a ubiquitin-conjugating enzyme (UBC13) were both required for Bcl10-induced NEMO ubiquitination and subsequent NF-κB activation. Furthermore, short interfering RNAs that reduced the expression of paracaspase and UBC13 abrogated the effects of Bcl10. Thus, the adaptor protein Bcl10 promotes activation of NF-κB transcription factors through paracaspase- and UBC13-dependent ubiquitination of NEMO.

Endocrine disruption by cadmium, a common environmental toxicant with paradoxical effects on reproduction.

Abstract: Cadmium (Cd2+) is a common environmental pollutant and a major constituent of tobacco smoke. Exposure to this heavy metal, which has no known beneficial physiological role, has been linked to a wide range of detrimental effects on mammalian reproduction. Intriguingly, depending on the identity of the steroidogenic tissue involved and the dosage used, it has been reported to either enhance or inhibit the biosynthesis of progesterone, a hormone that is inexorably linked to both normal ovarian cyclicity and the maintenance of pregnancy. Thus, Cd2+ has been shown to exert significant effects on ovarian and reproductive tract morphology, with extremely low dosages reported to stimulate ovarian luteal progesterone biosynthesis and high dosages inhibiting it. In addition, Cd2+ exposure during human pregnancy has been linked to decreased birth weights and premature birth, with the enhanced levels of placental Cd2+ resulting from maternal exposure to industrial wastes or tobacco smoke being associated with decreas...

Group awareness in distributed software development

Abstract: Open-source software development projects are almost always collaborative and distributed. Despite the difficulties imposed by distance, these projects have managed to produce large, complex, and successful systems. However, there is still little known about how open-source teams manage their collaboration. In this paper we look at one aspect of this issue: how distributed developers maintain group awareness. We interviewed developers, read project communication, and looked at project artifacts from three successful open source projects. We found that distributed developers do need to maintain awareness of one another, and that they maintain both a general awareness of the entire team and more detailed knowledge of people that they plan to work with. Although there are several sources of information, this awareness is maintained primarily through text-based communication (mailing lists and chat systems). These textual channels have several characteristics that help to support the maintenance of awareness, as long as developers are committed to reading the lists and to making their project communication public.

High temperature stress of Brassica napus during flowering reduces micro‐ and megagametophyte fertility, induces fruit abortion, and disrupts seed production

Abstract: High temperature stress (HTS), during flowering, decreases seed production in many plants. To determine the effect of a moderate HTS on flowering, fruit and seed set in Brassica napus, plants were exposed to a HTS (8/16 h dark/light, 18 degrees C night, ramped at 2 degrees C h-1, over 6 h, to 35 degrees C for 4 h, ramped at 2 degrees C h-1 back to 23 degrees C for 6 h) for 1 or 2 weeks after the initiation of flowering. Although flowering on the HTS-treated plants, during both the 1 week and 2 week HTS treatments, was equal to that of control-grown plants, fruit and seed development, as well as seed weight, were significantly reduced. Under HTS, flowers either developed into seedless, parthenocarpic fruit or aborted on the stem. At the cessation of the HTS, plants compensated for the lack of fruit and seed production by increasing the number of lateral inflorescences produced. During the HTS, pollen viability and germinability were slightly reduced. In vitro pollen tube growth at 35 degrees C, from both control pollen and pollen developed under a HTS, appeared abnormal, however, in vivo tube growth to the micropyle appeared normal. Reciprocal pollination of HTS or control pistils with HTS or control pollen indicated that the combined effects of HTS on both micro- and megagametophytes was required to knock out fruit and seed development. Expression profiles for a subset of HEAT SHOCK PROTEINs (HSP101, HSP70, HSP17.6) showed that both micro- and megagametophytes were thermosensitive despite HTS-induced expression from these genes.

Hydrogen sulfide-induced relaxation of resistance mesenteric artery beds of rats

Abstract: Hydrogen sulfide (H2S) has been shown recently to function as an important gasotransmitter. The present study investigated the vascular effects of H2S, both exogenously applied and endogenously gen...

Nest sites and nest webs for cavity-nesting communities in interior british columbia, canada: nest characteristics and niche partitioning

Abstract: The mixed forests of interior British Columbia, Canada, support a rich community of cavity nesters, accounting for about one-third of forest vertebrate species. For 20 cavity-nesting bird and six cavity-nesting mammal species, representing excavators and secondary cavity nesters, we measured nest-cavity and nest-tree characteristics over 8 years in Interior Douglas-fir (Pseudotsuga menziesii) forest ecosystems. There was overwhelming selection for quaking aspen (Populus tremuloides); 95% of 1692 cavity nests were in aspen, which comprised only 15% of trees available. The full range of live and dead trees were used, but we observed a strong preference for live trees with decay (45% of nests) or dead trees (45% of nests). A cluster analysis based on tree and cavity characteristics divided the community into five groups, including large- and medium-sized woodpeckers and a group comprised mostly of weak excavators. A fourth group included Northern Flickers (Colaptes auratus), the most abundant excava...

Beyond Visual Metaphor: A New Typology of Visual Rhetoric in Advertising

Abstract: The goal of rhetorical theory is always to organize the possibilities for persuasion within a domain and to relate each possible stratagem to specific desired outcomes. In this article we develop a visual rhetoric that differentiates the pictorial strategies available to advertisers and links them to consumer response. We propose a new typology that distinguishes nine types of visual rhetorical figures according to their degree of complexity and ambiguity. We then derive empirically testable predictions concerning how these different types of visual figures may influence such consumer responses as elaboration and belief change. The article concludes with a discussion of the importance of marrying textual analysis, as found in literary, semiotic and rhetorical disciplines, with the experimental methodology characteristic of social and cognitive psychology.

Generating capacity adequacy associated with wind energy

Abstract: The wind is a highly variable energy source and behaves far differently than conventional energy sources. This paper presents a methodology for capacity adequacy evaluation of power systems including wind energy. The results and discussions on two representative systems containing both conventional generation units and wind energy conversion systems (WECS) are presented. A Monte Carlo simulation approach is used to conduct the analysis. The hourly wind speeds are simulated using an autoregressive moving average time-series model. A wide range of studies were conducted on two different sized reliability test systems. The studies show that the contribution of a WECS to the reliability performance of a generation system can be quantified and is highly dependent on the wind site conditions. A WECS can make a significant reliability contribution given a reasonably high wind speed. Wind energy independence also has a significant positive impact on the reliability contribution of multiple WECS.

Efficacy and safety of the monoclonal anti-tumor necrosis factor antibody F(ab')2 fragment afelimomab in patients with severe sepsis and elevated interleukin-6 levels.

Abstract: Objective: To evaluate whether administration of afelimomab, an anti-tumor necrosis factor F(ab')2 monoclonal antibody fragment, would reduce 28-day all-cause mortality in patients with severe sepsis and elevated serum levels of IL-6. Design: Prospective, randomized, double-blind, placebo-controlled, multiple-center, phase III clinical trial. Setting: One hundred fifty-seven intensive care units in the United States and Canada. Patients: Subjects were 2,634 patients with severe sepsis secondary to documented infection, of whom 998 had elevated interleukin-6 levels. Interventions: Patients were stratified into two groups by means of a rapid qualitative interleukin-6 test kit designed to identify patients with serum interleukin-6 levels above (test positive) or below (test negative) approximately 1000 pg/mL. Of the 2,634 patients, 998 were stratified into the test-positive group, 1,636 into the test-negative group. They were then randomly assigned 1:1 to receive afelimomab 1 mg/kg or placebo for 3 days and were followed for 28 days. The a priori population for efficacy analysis was the group of patients with elevated baseline interleukin-6 levels as defined by a positive rapid interleukin-6 test result. Measurements and Main Results: In the group of patients with elevated interleukin-6 levels, the mortality rate was 243 of 510 (47.6%) in the placebo group and 213 of 488 (43.6%) in the afelimomab group. Using a logistic regression analysis, treatment with afelimomab was associated with an adjusted reduction in the risk of death of 5.8% (p .041) and a corresponding reduction of relative risk of death of 11.9%. Mortality rates for the placebo and afelimomab groups in the interleukin-6 test negative population were 234 of 819 (28.6%) and 208 of 817 (25.5%), respectively. In the overall population of interleukin-6 test positive and negative patients, the placebo and afelimomab mortality rates were 477 of 1,329 (35.9%)and 421 of 1,305 (32.2%), respectively. Afelimomab resulted in a significant reduction in tumor necrosis factor and interleukin-6 levels and a more rapid improvement in organ failure scores compared with placebo. The safety profile of afelimomab was similar to that of placebo. Conclusions: Afelimomab is safe, biologically active, and well tolerated in patients with severe sepsis, reduces 28-day all-cause mortality, and attenuates the severity of organ dysfunction in patients with elevated interleukin-6 levels. (Crit Care Med 2004; 32:2173‐2182)

A review of the occurrence and fate of naphthenic acids in aquatic environments.

Abstract: Naphthenic acids are comprised of a large collection of saturated aliphatic and alicyclic carboxylic acids found in hydrocarbon deposits (petroleum, oil sands bitumen, and crude oils) Naphthenic acids enter surface water systems primarily through effluent discharge, but also through groundwater mixing and erosion of riverbank oil deposits Of the possible environmental receptors (ie, air, soil, and water), the most significant is water Ambient levels of naphthenic acids in northern Alberta rivers in the Athabasca Oil Sands are generally below 1 mg L(-1) However, tailings pond waters may contain as high as 110 mg L(-1) The complexity of natural naphthenic acids in petroleum deposits poses an analytical challenge as reflected by the several techniques reported for quantitation of naphthenic acids in the environment Although naphthenic acids are known to be persistent biomarkers used in identification of oil source maturation, little is established regarding their relative degradation pathways in aquatic environments Published research related to the potential for microbiological degradation and adsorption to typical Athabasca Oil Sands soils reveal that naphthenic acids are likely to persist in the water column and, with prolonged exposure, accumulate in sediments However, other than a very general knowledge of environmental persistence, the occurrence and fate of naphthenic acids has been sparsely studied This article brings together some of those environmental persistence results, as well as detailed information regarding the origin of naphthenic acids in tailings ponds, chemistry and toxicological considerations, current analytical methods for aquatic sampling, and areas of future remediation research

Self-Concordance and Subjective Well-Being in Four Cultures:

Abstract: Sheldon and colleagues have recently focused research attention on the concept of self-concordance, in which people feel that they pursue their goals because the goals fit with their underlying interests and values rather than because others say they should pursue them. Self-concordant individuals typically evidence higher subjective well-being (SWB). But is this also true in non-Western cultures, which emphasize people’s duty to conform to societal expectations and group-centered norms? To address this question, this study assessed goal self-concordance and SWB in four different cultures. U.S., Chinese, and South Korean samples evidenced equal levels of self-concordance, whereas a Taiwanese sample evidenced somewhat less self-concordance. More importantly, self-concordance predicted SWB within every culture. It appears that “owning one’s actions”—that is, feeling that one’s goals are consistent with the self—may be important for most if not all humans.

Pattern of Pax7 expression during myogenesis in the posthatch chicken establishes a model for satellite cell differentiation and renewal.

Abstract: The paired-box transcription factor Pax7 plays a critical role in the specification of satellite cells in mouse skeletal muscle. In the present study, the position and number of Pax7-expressing cells found in muscles of growing and adult chickens confirm the presence of this protein in avian satellite cells. The expression pattern of Pax7 protein, along with the muscle regulatory proteins MyoD and myogenin, was additionally elucidated in myogenic cultures and in whole muscle from posthatch chickens. In cultures progressing from proliferation to differentiation, the expression of Pax7 in MyoD+ cells declined as the cells began expressing myogenin, suggesting Pax7 as an early marker for proliferating myoblasts. At all time points, some Pax7+ cells were negative for MyoD, resembling the reserve cell phenotype. Clonal analysis of muscle cell preparations demonstrated that single progenitors can give rise to both differentiating and reserve cells. In muscle tissues, Pax7 protein expression was the strongest by 1 day posthatch, declining on days 3 and 6 to a similar level. In contrast, myogenin expression peaked on day 3 and then dramatically declined. This finding was accompanied by a robust growth in fiber diameter between day 3 and 6. The distinctions in Pax7 and myogenin expression patterns, both in culture and in vivo, indicate that while some of the myoblasts differentiate and fuse into myofibers during early stages of posthatch growth, others retain their reserve cell capacity.

Diffuse axonal injury in children: clinical correlation with hemorrhagic lesions.

Abstract: An inception cohort of 40 children and adolescents with traumatic brain injury and suspected diffuse axonal injury were studied using a new high-resolution magnetic resonance imaging susceptibility-weighted technique that is very sensitive for hemorrhage. A blinded comparison was performed between the extent of parenchymal hemorrhage and initial clinical variables as well as outcomes measured at 6 to 12 months after injury. Children with lower Glasgow Coma Scale scores ( 4 days, n = 20) had a greater average number (p = 0.007) and volume (p = 0.008) of hemorrhagic lesions. Children with normal outcomes or mild disability (n = 30) at 6 to 12 months had, on average, fewer hemorrhagic lesions (p = 0.003) and lower volume (p = 0.003) of lesions than those who were moderately or severely disabled or in a vegetative state. Significant differences also were observed when comparing regional injury to clinical variables. Because susceptibility-weighted imaging is much more sensitive than conventional T2*-weighted gradient-echo sequences in detecting hemorrhagic diffuse axonal injury, more accurate and objective assessment of injury can be obtained early after insult, and may provide better prognostic information regarding duration of coma as well as long-term outcome.

Information asymmetry and the role of traceability systems

Abstract: The role of food traceability systems in resolving information asymmetry is explored. Three functions of traceability systems are identified: ex post reactive systems that allow the traceback of affected products in the event of a contamination problem so as to minimize social costs, ex post systems that facilitate the allocation of liability, and information systems that provide ex ante quality verification. A taxonomy of traceability systems illustrates the multidimensional nature of the information problems related to food safety and food quality. A model of ex ante quality verification and ex post traceability systems is used to demonstrate the different functions and incentives of a traceability system. Finally, examples of private sector and regulatory traceability initiatives are discussed within the context of the ex post and ex ante models developed in the paper. [EconLit citations: Q130; Q180; L150.] © 2004 Wiley Periodicals, Inc. Agribusiness 20: 397–415, 2004.

Wake structure of a finite circular cylinder of small aspect ratio

Abstract: The wake of a finite circular cylinder of small aspect ratio was studied with a seven-hole probe and thermal anemometry. The cylinder was mounted normal to a ground plane and was partially immersed in a turbulent boundary layer. The time-averaged velocity and streamwise vorticity fields showed the development of the tip vortex structures, the extent of the near-wake recirculation zone, the downwash phenomenon and base vortex structures within the boundary layer. The wake structure and power spectra were similar for cylinder aspect ratios of 5 to 9, but a distinctly different behaviour was observed for an aspect ratio of 3.

Hydrogen sulfide-induced apoptosis of human aorta smooth muscle cells via the activation of mitogen-activated protein kinases and caspase-3

Abstract: The endogenous production of hydrogen sulfide (H2S) and its physiological functions, including membrane hyperpolarization and smooth muscle cell relaxation, position this gas well in the family of gasotransmitters together with nitric oxide (NO) and carbon monoxide (CO). In this study, we demonstrate that H2S at physiologically relevant concentrations induced apoptosis of human aorta smooth muscle cells (HASMCs). Exposure of HASMCs to H2S did not induce necrosis as verified with Trypan blue exclusion and LDH release analysis. After inhibiting endogenous H2S production, exogenous H2S induced much more significant apoptosis, which was not altered by the presence of albumin or glutathione. H2S treatment increased the activities of ERK and p38 mitogen-activated protein kinase (MAPK), but not c-Jun N-terminal kinase activity. Suppression of extracellular signal-regulated kinase (ERK) activity, but not of p38 activity, inhibited the H2S-induced apoptosis of HASMCs. The activation of ERK by H2S in HASMCs was accompanied by increased caspase-3 activity. Inhibition of caspase-3 by AC-DEVD-CHO attenuated the H2S-induced cell apoptosis. Inhibition of ERK by U0126 decreased caspase-3 activity, whereas AC-DEVD-CHO did not alter ERK activity. In conclusion, exogenous H2S induces apoptosis of HASMCs, which is significantly affected by the endogenous H2S level. Of the three investigated MAPKs, only ERK played an active role in mediating H2S-induced apoptosis of HASMCs by activating caspase-3. These findings may help reveal novel mechanisms for many diseases linked to H2S-related abnormal cellular proliferation and apoptosis.

Rough vaccines in animal brucellosis: structural and genetic basis and present status.

Abstract: Brucellosis control and eradication requires serological tests and vaccines. Effective classical vaccines (S19 in cattle and Rev 1 in small ruminants), however, induce antibodies to the O-polysaccharide of the lipopolysaccharide which may be difficult to distinguish from those resulting from infection and may thus complicate diagnosis. Rough attenuated mutants lack the O-polysaccharide and would solve this problem if eliciting protective immunity; the empirically obtained rough mutants 45/20 and RB51 have been used as vaccines. Strain 45/20 is reportedly unstable and it is not presently used. RB51 is increasingly used instead of S19 in some countries but it is rifampicin resistant and its effectiveness is controversial. Some controlled experiments have found good or absolute protection in adult cattle vaccinated orally (full dose) or subcutaneously (reduced dose) and in one field experiment, RB51 was reported to afford absolute protection to calves and to perform better than S19. Controlled experiments in calves, however, have shown reduced doses of RB51 to be ineffective, full doses only partially effective, and RB51 less effective than S19 against severe challenges. Moreover, other observations suggest that RB51 is ineffective when prevalence is high. RB51 is not useful in sheep and evidence in goats is preliminary and contradictory. Rough mutants obtained by molecular biology methods on the knowledge of the genetics and structure of Brucella lipopolysaccharide may offer alternatives. The B. abortus manBcore (rfbK) mutant seems promising in cattle, and analyses in mice suggest that mutations affecting only the O-polysaccharide result in better vaccines than those affecting both core and O-polysaccharide. Possible uses of rough vaccines also include boosting immunity by revaccination but solid evidence on its effectiveness, safety and practicality is not available.