Showing papers by "Memorial University of Newfoundland published in 1999"

Food applications of chitin and chitosans

Abstract: Chitin is the second most abundant natural biopolymer after cellulose. The chemical structure of chitin is similar to that of cellulose with 2-acetamido-2-deoxy-β- d -glucose (NAG) monomers attached via β(14) linkages. Chitosan is the deacetylated (to varying degrees) form of chitin, which, unlike chitin, is soluble in acidic solutions. Application of chitinous products in foods and pharmaceuticals as well as processing aids has received considerable attention in recent years as exotic synthetic compounds are losing their appeal. This review summarizes some of the important developments related to food applications of chitin, chitosan and their derivatives.

The Clinical Epidemiology of Cardiac Disease in Chronic Renal Failure

Abstract: The annual mortality from cardiovascular disease in dialysis patients is substantially higher than in the general population ([Figure 1][1]) ([1][2]). The 5-yr survival of men >64 yr old starting dialysis is worse than that of men with colon cancer and prostate cancer ([2][3]). The 5-yr survival of

The sequence of events around the epicentre of the 1929 Grand Banks earthquake: initiation of debris flows and turbidity current inferred from sidescan sonar

Abstract: Continental slope sediment failures around the epicentre of the 1929 ‘Grand Banks’ earthquake have been imaged with the SAR (Systeme Acoustique Remorque) high-resolution, deep-towed sidescan sonar and sub-bottom profiler. The data are augmented by seismic reflection profiles, cores and observations from submersibles. Failure occurs only in water depths greater than about 650 m. Rotational, retrogressive slumps, on a variety of scales, appear to have been initiated on local steep areas of seabed above shallow (5–25 m) regional shear planes covering a large area of the failure zone. The slumps pass downslope into debris flows, which include blocky lemniscate bodies and intervening channels. Clear evidence of current erosion is found only in steep-sided valleys: we infer that debris flows passed through hydraulic jumps on these steep slopes and were transformed into turbidity currents which then evolved ignitively. Delayed retrogressive failure and transformation of debris flows into turbidity currents through hydraulic jumps provide a mechanism to produce a turbidity current with sustained flow over many hours.

Encouraging narratives in preschoolers: an intervention study.

Abstract: Twenty economically disadvantaged preschoolers (mean age 3;7) were randomly assigned to an intervention or a control group, and their mothers' styles of eliciting narratives from their children were assessed before and after intervention. Mothers of intervention children were encouraged to spend more time in narrative conversation, ask more open-ended and context-eliciting questions, and encourage longer narratives through back-channel responses. Children's narrative and vocabulary skills were assessed before and after the year-long intervention and 14 children participated in a follow-up assessment a year later. Narrative measures included the number and length of narratives as well as how decontextualized and informative they were. Intervention children showed significant vocabulary improvement immediately after intervention terminated, and a year later they showed overall improvements in narrative skill. In particular, intervention children produced more context-setting descriptions about where and especially when the described events took place. Such decontextualized language has been emphasized as important for literacy acquisition.

Analysis of direct action fuzzy PID controller structures

Abstract: The majority of the research work on fuzzy PID controllers focuses on the conventional two-input PI or PD type controller proposed by Mamdani (1974). However, fuzzy PID controller design is still a complex task due to the involvement of a large number of parameters in defining the fuzzy rule base. This paper investigates different fuzzy PID controller structures, including the Mamdani-type controller. By expressing the fuzzy rules in different forms, each PLD structure is distinctly identified. For purpose of analysis, a linear-like fuzzy controller is defined. A simple analytical procedure is developed to deduce the closed form solution for a three-input fuzzy inference. This solution is used to identify the fuzzy PID action of each structure type in the dissociated form. The solution for single-input-single-output nonlinear fuzzy inferences illustrates the effect of nonlinearity tuning. The design of a fuzzy PID controller is then treated as a two-level tuning problem. The first level tunes the nonlinear PID gains and the second level tunes the linear gains, including scale factors of fuzzy variables. By assigning a minimum number of rules to each type, the linear and nonlinear gains are deduced and explicitly presented. The tuning characteristics of different fuzzy PID structures are evaluated with respect to their functional behaviors. The rule decoupled and one-input rule structures proposed in this paper provide greater flexibility and better functional properties than the conventional fuzzy PHD structures.

Leadership emergence in autonomous work teams: Antecedents and outcomes.

Abstract: The aim of this study was to investigate (a) personality attributes and cognitive ability (g) as determinants of leadership emergence in teams, and (b) the impact of leadership that can emerge from the team leader (operationalized as the team member with the highest leadership score) and other team members (staff) on team performance. Autonomous work team members who had been working together for 13 weeks were studied. Participants were 480 undergraduates in 94 initially leaderless teams of 5 or 6. We found that leadership emergence was associated most strongly with g, followed by conscientiousness, extraversion, and emotional stability. Teams performed best when both the team leader and staff were high in leadership. Furthermore, an effective team leader does not ameliorate the negative affects of a staff low in leadership.

Evening Primrose Meal: A Source of Natural Antioxidants and Scavenger of Hydrogen Peroxide and Oxygen-Derived Free Radicals

Abstract: Evening primrose meal (EPM: 1% and 2%, w/w) reduced (p ≤ 0.05) the formation of 2-thiobarbituric acid-reactive substances (TBARS), hexanal, and total volatiles in cooked comminuted pork by 43.6−72.6%. Phenolic compounds in the EPM were extracted under optimum conditions (with 56% acetone at 71 °C for 47 min) predicted by a multivariate analysis. The resulting evening primrose crude extract (EPCE) inhibited the bleaching of β-carotene in a model system. After 2 h of assay, the system containing 200 ppm EPCE [as (+)catechin equivalents] retained 86% of the initial β-carotene whereas the control retained only 11%. Inhibition of the formation of TBARS, hexanal, and total volatiles in the cooked comminuted pork containing 200 ppm EPCE [as (+)catechin equivalents] ranged from 67.3% to 97.5%. The EPCE inhibited the formation of conjugated dienes, hexanal, and total volatiles in stripped-bulk corn oil (18.5−63.6% inhibition) and stripped-corn oil-in-water emulsion systems (31.7−65.6% inhibition). Hydrogen peroxi...

Docosahexaenoic acid ingestion inhibits natural killer cell activity and production of inflammatory mediators in young healthy men

Abstract: The purpose of this study was to examine the effects of feeding docosahexaenoic acid (DHA) as triacylglycerol on the fatty acid composition, eicosanoid production, and select activities of human peripheral blood mononuclear cells (PBMNC). A 120-d study with 11 healthy men was conducted at the Metabolic Research Unit of Western Human Nutrition Reach Center. Four subjects (control group) were fed the stabilization diet throughout the study; the remaining seven subjects were fed the basal diet for the first 30 d, followed by 6 g DHA/d for the next 90 d. DHA replaced an equivalent amount of linoleic acid; the two diets were comparable in their total fat and all other nutrients. Both diets were supplemented with 20 mg d α-tocopherol acetate per day. PBMNC fatty acid composition and eicosanoid production were examined on day 30 and 113; immune cell functions were tested on day 22, 30, 78, 85, 106, and 113. DHA feeding increased its concentration from 2.3 to 7.4 wt% in the PBMNC total lipids, and decreased arachidonic acid concentration from 19.8 to 10.7 wt%. It also lowered prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) production, in response to lipopolysaccharide, by 60–75%. Natural killer cell activity and in vitro secretion of interleukin-1β and tumor necrosis factor α were significantly reduced by DHA feeding. These parameters remained unchanged in the subjects fed the control diet. B-cell functions as reported here and T-cell functions that we reported previously were not altered by DHA feeding. Our results show that inhibitory effects of DHA on immune cell functions varied with the cell type, and that the inhibitory effects are not mediated through increased production of PGE2 and LTB4.

New methodology for analytical and optimal design of fuzzy PID controllers

Abstract: Describes a methodology for the systematic design of fuzzy PID controllers based on theoretical fuzzy analysis and, genetic-based optimization. An important feature of the proposed controller is its simple structure. It uses a one-input fuzzy inference with three rules and at most six tuning parameters. A closed-form solution for the control action is defined in terms of the nonlinear tuning parameters. The nonlinear proportional gain is explicitly derived in the error domain. A conservative design strategy is proposed for realizing a guaranteed-PID-performance (GPP) fuzzy controller. This strategy suggests that a fuzzy PID controller should be able to produce a linear function from its nonlinearity tuning of the system. The proposed PID system is able to produce a close approximation of a linear function for approximating the GPP system. This GPP system, incorporated with a genetic solver for the optimization, will provide the performance no worse than the corresponding linear controller with respect to the specific performance criteria. Two indexes, linearity approximation index (LAI) and nonlinearity variation index (NVI), are suggested for evaluating the nonlinear design of fuzzy controllers. The proposed control system has been applied to several first-order, second-order, and fifth-order processes. Simulation results show that the proposed fuzzy PID controller produces superior control performance to the conventional PID controllers, particularly in handling nonlinearities due to time delay and saturation.

Nutrition and immunology: from the clinic to cellular biology and back again.

Abstract: Diet and immunity have been known to be linked to each other for centuries. In the last 30 years systematic studies have confirmed that nutrient deficiencies impair immune response and lead to frequent severe infections resulting in increased mortality, especially in children. Protein-energy malnutrition results in reduced number and functions of T-cells, phagocytic cells and secretory immunoglobulin A antibody response. In addition, levels of many complement components are reduced. Similar findings have been reported for moderate deficiencies of individual nutrients such as trace minerals and vitamins, particularly Zn, Fe, Se, vitamins A, B6, C and E. For example, Zn deficiency is associated with profound impairment of cell-mediated immunity such as lymphocyte stimulation response, decreased CD4+:CD8+ cells, and decreased chemotaxis of phagocytes. In addition, the level of thymulin, which is a Zn-dependent hormone, is markedly decreased. The use of nutrient supplements, singly or in combination, stimulates immune response and may result in fewer infections, particularly in the elderly, low-birth-weight infants and malnourished critically-ill patients in hospitals. The interactions between nutrition and the immune system are of clinical, practical and public health importance.

An ocean-basin-wide mark-recapture study of the North Atlantic humpback whale (Megaptera novaeangliae)

Abstract: Although much is known about the humpback whale, Megaptera novaeangliae, regional studies have been unable to answer several questions that are central to the conservation and management of this endangered species. To resolve uncertainties about population size, as well as the spatial and genetic structure of the humpback whale population in the North Atlantic, we conducted a two-year ocean-basin-wide photographic and biopsy study in 1992-1993. Photographic and skin-biopsy sampling was conducted of animals in feeding and breeding areas throughout most of the range of this species in the North Atlantic, from the West Indies breeding grounds through all known feeding areas as far north as arctic Norway. A standardized sampling protocol was designed to maximize sample sizes while attempting to ensure equal probability of sampling, so that estimates of abundance would be as accurate and as precise as possible. During 666 d at sea aboard 28 vessels, 4,207 tail fluke photographs and 2,326 skin biopsies were collected. Molecular analyses of all biopsies included determination of sex, genotype using six microsatellite loci, and mitochondrial control region sequence. The photographs and microsatellite loci were used to identify 2,998 and 2,015 individual whales, respectively. Previously published results from this study have addressed spatial distribution, migration, and genetic relationships. Here, we present new estimates of total abundance in this ocean using photographic data, as well as overall and sex-specific estimates using biopsy data. We identify several potential sampling biases using only breeding-area samples and report a consistent mark-recapture estimate of oceanwide abundance derived from photographic identification, using both breeding and feeding-area data, of 10,600 (95% confidence interval 9,300-12,100). We also report a comparable, but less precise, biopsy-based estimate of 10,400 (95% confidence interval of 8,000-13,600). These estimates are significantly larger and more precise than estimates made for the 1980s, potentially reflecting population growth. In contrast, significantly lower and less consistent estimates were obtained using between-feeding-area or between-breeding-area sampling. Reasons for the lower estimates using the results of sampling in the same areas in subsequent years are discussed. Overall, the results of this ocean-basin-wide study demonstrate that an oceanwide approach to population assessment of baleen whales is practicable and results in a more comprehensive understanding of population abundance and biology than can be gained from smaller-scale efforts.

Using Advertising Alliances for New Product Introduction: Interactions between Product Complementarity and Promotional Strategies:

Abstract: In this article, the authors investigate the effectiveness of advertising alliances (in which two brands from different product categories are featured together in an advertisement) for introducing...

Finding the Medial Axis of a Simple Polygon in Linear Time

Abstract: We give a linear-time algorithm for computing the medial axis of a simple polygon P . This answers a long-standing open question—previously, the best deterministic algorithm ran in O(n log n) time. We decompose P into pseudonormal histograms, then influence histograms, then xy monotone histograms. We can compute the medial axes for xy monotone histograms and merge to obtain the medial axis for P .

Chemical Synthesis, Characterization, and Electrochemical Studies of Poly(3,4-ethylenedioxythiophene)/Poly(styrene-4-sulfonate) Composites

Abstract: Poly(3,4-ethylenedioxythiophene)/poly(styrene-4-sulfonate) (PEDOT/PSS) composites have been prepared from aqueous and aqueous acetonitrile solutions of EDOT and NaPSS by oxidation using Fe(III) salts. Powders with PEDOT to PSS ratios ranging from 0.3 to 4.2 and electronic conductivities as high as 10 S cm-1 have been obtained in good yields. The PEDOT/PSS blends are cation exchangers and exhibit facile eletrochemistry in both aqueous and acetonitrile media. Impedance measurements have shown that 30 μm thick PEDOT/PSS layers have proton conductivities as high as 0.03 S cm-1.

Interviewing preschoolers: comparisons of yes/no and wh- questions.

Abstract: This study investigated the influence of question format on preschool-aged children's errors, their response accuracy, and their tendency to say "I don't know" when given non-misleading questions in a neutral, unbiased context. Children (3 to 5 years old) participated in a craft-making session that included a staged "accident" with two experimenters differing in gender and appearance; the environment also had several distinctive features. One week later children were interviewed about actions, participants, and environment; questions were yes/no format with the veridical response "yes" ("yes" questions), yes/no format with the veridical response "no" ("no" questions), and specific wh- format questions. Question format substantially influenced children's responses: they were most likely to make errors if asked "no" questions, and were unlikely to answer either yes/no question with "I don't know." In contrast, children spontaneously and frequently said "I don't know" to wh- questions about content they did not recall (environment), but not about content that was well recalled (actions). Implications of question format for reliability of eyewitness testimony by preschoolers are discussed.

The piecewise polynomial collocation method for nonlinear weakly singular Volterra equations

Abstract: Second-kind Volterra integral equations with weakly singular kernels typically have solutions which are nonsmooth near the initial point of the interval of integration. Using an adaptation of the analysis originally developed for nonlinear weakly singular Fredholm integral equations, we present a complete discussion of the optimal (global and local) order of convergence of piecewise polynomial collocation methods on graded grids for nonlinear Volterra integral equations with algebraic or logarithmic singularities in their kernels.

Miscellanea. On the efficiency of regression estimators in generalised linear models for longitudinal data

Abstract: SUMMARY Liang & Zeger (1986) introduced a generalised estimating equations approach based on a 'working' correlation matrix to obtain consistent and efficient estimators of regression parameters in the class of generalised linear models for repeated measures data. As demonstrated by Crowder (1995), because of the uncertainty of definition of the working correlation matrix, the Liang-Zeger approach may in some cases lead to a complete breakdown of the estimation of the regression parameters. In this paper we show that, even though the Liang-Zeger approach in many situations yields consistent estimators for the regression parameters, these estimators are usually inefficient as compared to the regression estimators obtained by using the independence estimating equations approach.