Showing papers by "Memorial University of Newfoundland published in 1996"

Inter-laboratory note. Laser ablation inductively coupled plasma mass spectrometric transient signal data acquisition and analyte concentration calculation

Abstract: Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) produces complex, time-dependent signals. These require significantly different treatment both during data acquisition and reduction from the more steady-state signals produced by solution sample introduction. This paper discusses, in detail, data acquisition and reduction considerations in LA-ICP-MS analysis. Optimum data acquisition parameters are suggested. Equations are derived for the calculation of sample concentrations and LOD when time-resolved data acquisition is employed, sensitivity calibration is obtained from reference materials with known analyte concentrations and naturally occurring internal standards are used to correct for the multiplicative correction factors of drift, matrix effects and the amount of material ablated and transported to the ICP.

A full genome search in multiple sclerosis

Abstract: The aetiology of multiple sclerosis (MS) is uncertain. There is strong circumstantial evidence to indicate it is an autoimmune complex trait. Risks for first degree relatives are increased some 20 fold over the general population. Twin studies have shown monozygotic concordance rates of 25-30% compared to 4% for dizygotic twins and siblings. Studies of adoptees and half sibs show that familial risk is determined by genes, but environmental factors strongly influence observed geographic differences. Studies of candidate genes have been largely unrewarding. We report a genome search using 257 microsatellite markers with average spacing of 15.2 cM in 100 sibling pairs (Table 1, data set 1 - DS1). A locus of lambda>3 was excluded from 88% of the genome. Five loci with maximum lod scores (MLS) of >1 were identified on chromosomes 2, 3, 5, 11 and X. Two additional data sets containing 44 (Table 1, DS2) and 78 sib pairs (Table 1, DS3) respectively, were used to further evaluate the HLA region on 6p21 and a locus on chromosome 5 with an MLS of 4.24. Markers within 6p21 gave MLS of 0.65 (non-significant, NS). However, D6S461, just outside the HLA region, showed significant evidence for linkage disequilibrium by the transmission disequilibrium test (TDT), in all three data sets (for DS1 chi2 = 10.8, adjusted P < 0.01)(DS2 and DS3 chi2 = 10.9, P < 0.0005), suggesting a modest susceptibility locus in this region. On chromosome 5p results from all three data sets (222 sib pairs) yielded a multipoint MLS of 1.6. The results support genetic epidemiological evidence that several genes interact epistatically to determine heritable susceptibility.

Hypoalbuminemia, cardiac morbidity, and mortality in end-stage renal disease

Abstract: A cohort of 432 ESRD (261 hemodialysis and 171 peritoneal dialysis) patients was followed up prospectively for an average of 41 months. Baseline and annual demographic, clinical, and echocardiographic assessments were performed, as well as serial clinical and laboratory tests measured monthly while patients were on dialysis therapy. Among hemodialysis patients, after adjustment was made for age, diabetes, and ischemic heart disease, as well as hemoglobin and blood pressure levels measured serially, a 10-g/L fall in mean serum albumin level was independently associated with the the development of de novo (relative risk [RR], 2.22; P = 0.001) and recurrent cardiac failure (RR, 3.84; P = 0.003), de novo (RR, 5.29; P = 0.001) and recurrent ischemic heart disease (RR, 4.24; P = 0.005), cardiac mortality (RR, 5.60; P = 0.001), and overall mortality (RR, 4.33; P < 0.001). Among peritoneal dialysis patients, a 10-g/L fall in mean serum albumin level was independently associated with the progression of left ventricular dilation as seen on follow-up echocardiography (beta, 13.4 mL/m2; P = 0.014), the development of de novo cardiac failure (RR, 4.16; P = 0.003), and overall mortality (RR, 2.06; P < 0.001). Hypoalbuminemia, a major adverse prognostic factor in dialysis patients, is strongly associated with cardiac disease.

Human Culture and Large Carnivore Conservation in North America

Abstract: We examined and compared human attitudes toward wolves (Canis lupus), grizzly bears (Ursus arctos horribilis), and mountain lions (Puma concolor) in North America, with an emphasis on the Rocky Mountains of the United States and Canada. Primary research, literature review, and secondary data were in- cluded in the analysis. Wolves were historically persecuted by Euro-American settlers, but they have been the focus of a significant attitudinal transformation during the latter half of this century. Many now view the wolf in positive and protective ways. Considerable variation remains, however, in contemporary attitudes. At- titudes toward mountain lions have been highly ambivalent, never assuming the prominence or clarity of views on wolves. The behavior and physiology of the species, along with human psychological factors, are im- portant reasons for the difference in human perceptions of wolves and mountain lions. We also examined at- titudes toward grizzly bears. Many indigenous cultures revered grizzly bears, although European settlers were interested in exploiting and eliminating them. Today, perceptions of grizzly bears range from positive to negative. Our recommendations include targeting key groups with education programs, building support through the use of spokespeople within the target groups, integrating human and ecological concerns, and de- signing species-specific education initiatives in some cases.

Analysis and design of a multiple feedback loop control strategy for single-phase voltage-source UPS inverters

Abstract: This paper presents the analysis and design of a multiple feedback loop control scheme for single-phase voltage-source uninterruptible power supply (UPS) inverters with an L-C filter. The control scheme is based on sensing the current in the capacitor of the load filter and using it in an inner feedback loop. An outer voltage feedback loop is also incorporated to ensure that the load voltage is sinusoidal and well regulated. A general state-space averaged model of the UPS system is first derived and used to establish the steady-steady quiescent point. A linearized small signal dynamic model is then developed from the system general model using perturbation and small-signal approximation. The linearized system model is employed to examine the incremental dynamics of the power circuit and select appropriate feedback variables for stable operation of the closed-loop UPS system. Experimental verification of a laboratory model of the UPS system under the proposed closed-loop operation is provided for both linear and nonlinear loads. It is shown that the control scheme offers improved performance measures over existing schemes, It is simple to implement and capable of producing nearly perfect sinusoidal load voltage waveform at moderate switching frequency and reasonable size of filter parameters. Furthermore, the scheme has excellent dynamic response and high voltage utilization of the DC source.

Magnetostructural Correlations in Bis(m(2)-phenoxide)-Bridged Macrocyclic Dinuclear Copper(II) Complexes. Influence of Electron-Withdrawing Substituents on Exchange Coupling.

Abstract: Macrocyclic dicopper(II) complexes derived from 2,6-di(R)formylphenols and various linking diamines are surveyed and their magnetic and structural properties assessed. For those systems with "flat" dinuclear centers and no electronic perturbations associated with electron-withdrawing ligands or ligand groups, the complexes exhibit a "straight-line" relationship between exchange integral and phenoxide bridge angle. Within the angle range 98.8-104.7 degrees, 11 complexes are included with -2J in the range 689-902 cm(-)(1). When electron-withdrawing species are present, either as ligands or as groups bound to the macrocycle itself, considerable suppression of the antiferromagnetic exchange component is observed. Single-crystal X-ray diffraction studies are reported for three complexes. [Cu(2)(L1)(H(2)O)(2)]F(2)(CH(3)OH)(2) (1) crystallized in the triclinic system, space group Po, with a = 8.1878(5) A, b = 9.0346(7) A, c = 10.4048(7) A, alpha = 103.672(6) degrees, beta = 101.163(5) degrees, gamma = 104.017(5) degrees, and Z = 1. [Cu(2)(L2)Cl(2)] [Cu(2)(L2) (H(2)O)(2)]Cl(ClO(4)).5.5H(2)O (2) crystallized in the monoclinic system, space group P2(1)/n, with a = 14.4305(5) A, b = 24.3149(8) A, c = 18.6584(8) A, beta = 111.282(3) degrees, and Z = 4. [Cu(2)(L3)(H(2)O)(2)](BF(4))(2) (3) crystallized in the triclinic system, space group Po, with a = 8.6127(4) A, b = 8.6321(7) A, c = 10.8430(10) A, a = 74.390(10) degrees, beta = 86.050(10) degrees, gamma = 76.350(10) degrees, and Z = 2. Square pyramidal copper ion stereochemistries are observed in all cases, with axially coordinated halogens or water molecules. Strong antiferromagnetic exchange is observed for all complexes (-2J = 784(8) cm(-)(1), Cu-O-Cu 103.65(10) degrees (1); -2J = 801(11) cm(-)(1), Cu-O-Cu 102.4(3), 107.5(3), 102.9(3), 106.1(3) degrees (2); -2J = 689(3) cm(-)(1), Cu-O-Cu 98.8(4) degrees (3)). The presence of electron-withdrawing CN groups on the periphery of the macrocyclic ligand leads to substantially reduced antiferromagnetic exchange.

Children's memory for traumatic injury.

Abstract: Children between 2 and 13 years who suffered traumatic injury necessitating hospital emergency room treatment were recruited as subjects. They (and adult witnesses) were interviewed a few days and 6 months later, using free and probed recall, about both injury and hospital treatment. Children at all ages were able to provide considerable information about both stressful events, although the amount of detail increased with age. They also made few commission errors. Surprisingly, children's distress at time of injury did not affect the amount or accuracy of their recall of that event, whereas distress during hospital treatment did decrease recall. A tripartite classification into 3 categories of detail was used: central, peripheral--inside the emotional events, or peripheral--outside those events. Children's recall differed depending upon detail category. Implications for children's testimony are discussed.

Nutrition, immunity and infection: From basic knowledge of dietary manipulation of immune responses to practical application of ameliorating suffering and improving survival

Abstract: Thy food is such As has been belch’d on by infected lungs. William Shakespeare, Pericles , IV, vi, 178. The causal relationship between the conjugal pair of famine and pestilence has been known for millennia. It is recognized that malnutrition and infection are the two major obstacles for health, development, and survival worldwide, and poverty and ignorance are the most significant contributing factors (1, 2). Epidemiological observations have confirmed that infection and malnutrition aggravate each other. However, nutrition does not influence all infections equally (3, 4). For some infections (e.g., pneumonia, bacterial and viral diarrhea, measles, tuberculosis), there is overwhelming evidence that the clinical course and final outcome are affected adversely by nutritional deficiency. For others (e.g., viral encephalitis, tetanus), the effect of nutritional status is minimal. For still others (e.g., influenza virus, human immunodeficiency virus), nutrition exerts a moderate influence. It is now established that nutritional deficiency is commonly associated with impaired immune responses, particularly cell-mediated immunity, phagocyte function, cytokine production, secretory antibody response, antibody affinity, and the complement system (1, 5, 6). In fact, malnutrition is the commonest cause of immunodeficiency worldwide. There was a three-pronged impetus for systematic studies of immune responses in undernourished individuals. First, there was a plethora of public health data indicating an interaction, usually synergistic but occasionally antagonistic, between malnutrition and infection (3). Second, new concepts and novel techniques in immunology emerged in the 1960s and 1970s. Third, dramatic human stories and demographic data stimulated individual scientists, as the following example shows (7). My interest in nutrition-immunity interactions was kindled by two cases: first, the story with an unhappy ending, of a child; second, the bleak scenario of the Third World. Eighteen-month-old Kamala was thin, her skin pale as wax, and her lungs screaming for air. She wore a …

Analysis of brushless permanent magnet synchronous motors

Abstract: A brief design review of permanent magnet synchronous motors has been presented. A procedure has been developed to predict the steady state and dynamic performances of a brushless permanent magnet synchronous motor. Finite element analysis has been combined with a lumped parameter circuit model in order to provide satisfactory engineering information. To this end, two coordinated steps are involved. One is to develop a unified lumped parameter circuit model for both steady state and dynamic analysis. The second step is to extract the individual lumped parameters from finite element solutions based on corresponding equivalent circuits, each with a pre-determined topology. The proposed techniques have been experimentally verified in a laboratory permanent magnet synchronous motor.

Elemental fractionation in laser ablation inductively coupled plasma mass spectrometry.

Abstract: The major challenge to the use of laser ablation sample introduction, combined with inductively coupled plasma mass spectrometry, is the problem of calibration. In the geological analysis of minerals, calibration is complicated by the extraordinarily wide variety of sample matrices which may be encountered. While there is a lack of mineral standards with well characterized concentrations near 1 μg/g, the NIST glass reference materials (SRM 610–617) have been demonstrated to be very useful for the analysis of a wide variety of lithophile elements in silicate samples. An internal reference element, for which the concentration is known in the sample, has been widely used to make corrections for the multiplicative effects of volume (or weight) of the sample ablated, instrument drift, and matrix effects. This procedure works extremely well where elements being determined and the internal reference element being used share similar ablation behaviours; i.e., they do not fractionate progressively during the ablation and transport process. In this study, it is demonstrated that, in terms of ablation behaviour, elements fall into several distinct clusters and that the elements within these clusters correlate well with each other during a period of ablation. Thus, elements within a cluster can be determined using an internal reference element from within the same cluster. While a combination of periodic varying properties typifies the clusters, the geochemical classification of elements into lithophile (silicate loving), and chalcophile (sulphide loving) appears to offer the best characterization of the major groups.

The Evolution of Internal Wave Undular Bores: Comparisons of a Fully Nonlinear Numerical Model with Weakly Nonlinear Theory

Abstract: The validity of shallow-water, weakly nonlinear theory for describing the evolution of a single large internal wave depression into an undular bore is explored by comparing theoretical results with results obtained from a fully nonlinear numerical model. Inclusion of second-order nonlinear and dispersive terms significantly improves the agreement. Solutions of the KdV and extended KdV equations, which includes second-order nonlinearity, overpredict the wave amplitudes in the undular bore. Inclusion of all second-order nonlinear and dispersive terms significantly improves the predicted amplitudes; however, the resulting evolution equation breaks down for sufficiently large waves. This can be corrected by modifying the linear terms in the equation to give a modified equation. Solutions of this modified second-order equation are in much better agreement with the model results than are the solutions of the KdV equation and the extended KdV equations.

Performance of a single-beam pulse-to-pulse coherent Doppler profiler

Abstract: We report on the testing of a single-beam 1.7-MHz coherent Doppler sonar. The system is PC-controlled, using a digital signal processor (DSP) to acquire and extract the velocity and backscatter amplitude data. Results from a series of tow-tank calibration tests demonstrate an accuracy in the order of 5 mm s/sup -1/ for data rates of 10 profiles/second over a 1-2 m range with 1.5-cm range bins. An expression for system accuracy is developed which allows generalization to other pulse-to-pulse coherent Doppler systems. We present data showing the systematic decorrelation of backscatter signals due to particle advection: increased decorrelation is seen in the transducer near-field. Example observations of velocity profiles in laboratory-generated waves are presented.

Neuroprotection After Several Days of Mild, Drug-Induced Hypothermia

Abstract: Stroke trials are initiated after demonstrated pharmacological protection in animal models. NBQX protects CA1 neurons against global ischemia; however, this glutamate antagonist induces a period of subnormal temperature (e.g., a decrease of only 1.0-1.5 degrees C) lasting several days. In this study, NBQX (3 x 30 mg/kg, i.p.) was administered starting 60 min after reperfusion, and brain temperature had declined significantly below vehicle-treated animals by 2 h after reperfusion. When the postischemic brain temperature of NBQX-treated gerbils was regulated, no neuronal protection was found. Mimicking an NBQX-induced temperature profile for 28 h postischemia yielded histological protection 4 days later comparable to that of NBQX. However, both the NBQX and temperature simulation groups showed decreased protection after 10-day survival. Our data suggest that a protracted period of subnormal temperature during postischemic period can obscure the interpretation of preclinical drug studies.

Structure and composition of fish muscle

Abstract: Fish and marine invertebrates are an important part of our diet as they contribute to the intake of health‐pro omega‐3 fatty acids and possibly to prevention and treatment of coronary heart diseases. The crude protein contents of seafoods generally vary between 11.0% and 28.4% (usually about 19.0%), and the content of lipid in muscle tissue is inversely related to its moisture content. The contribution of non‐protein nitrogenous compounds to the total crude protein content of seafoods depends on the species of raw material and range from 10% to 40%. While the amount of fat‐soluble vitamins in seafoods is often higher than those in land animals and depends, to a large extent, on the species, the content of water‐soluble vitamins in seafoods is less dependent upon the species. The content of minerals in seafoods is slightly higher than those in terrestrial animals. The flavor of seafoods depends on the species, the fat content, and the presence as well as the type of nonprotein nitrogenous compounds.

Vagal efferent projections: viscerotopy, neurochemistry and effects of vagotomy.

Abstract: Publisher Summary This chapter focuses on the viscerotopic organization of the cells of origin of the vagus nerve with emphasis on subnuclear organization in the vagus nerve (DMV) and nucleus ambiguus (AMB). Aspects of the neurochemistry and afferent inputs of the DMV and AMB are discussed in terms of the identified viscerotopic organization. The effects of vagus nerve lesions will be assessed in terms of subnuclear differences as they relate to the connectivity connectivity and neurochemistry of the DMV and AMB. The chapter shows that the viscerotopic representation in the two nuclei comports with topographic patterns of specific neurochemicals and that vagal lesions cause differential responses in chemically and functionally distinct groups of neurons in the DMV and AMB. Neurochemical changes following vagal lesions are selective for specific viscera and are not uniform among functional subdivisions in the two nuclei. The viscerotopic organization of vagal motoneurons, thus, may also be reflected in differences in trophic support and pathophysiology.

Vertical Flux of Biogenic Carbon in the Ocean: Is There Food Web Control?

Abstract: Models of biogenic carbon (BC) flux assume that short herbivorous food chains lead to high export, whereas complex microbial or omnivorous food webs lead to recycling and low export, and that export of BC from the euphotic zone equals new production (NP). In the Gulf of St. Lawrence, particulate organic carbon fluxes were similar during the spring phytoplankton bloom, when herbivory dominated, and during nonbloom conditions, when microbial and omnivorous food webs dominated. In contrast, NP was 1.2 to 161 times greater during the bloom than after it. Thus, neither food web structure nor NP can predict the magnitude or patterns of BC export, particularly on time scales over which the ocean is in nonequilibrium conditions.

Use of response surface methodology to describe the combined effects of pH, temperature and E/S ratio on the hydrolysis of dogfish (Squalus acanthias) muscle

Abstract: Response surface methodology was used to study the effects of pH temperature and enzyme-substrate ratio (E/S) on the degree of hydrolysis (DH) of dogfish muscle protein. The effect of the hydrolysis variables was described using a three-level Box-Benhken factorial design giving a mathematical model that shows the influence of each variable and their interactions. Based on degree of hydrolysis (DH) of the original substrate, the hydrolysis variables were optimized at a pH of 8.3, a hydrolysis temperature of 53.6 degrees C and an E/S of 3.6% (w/w). The coefficient of determination (R2ad) was greater than 95%, and a lack-of-fit test revealed a non-significant value for the DH model equation, indicating that the regression equation was adequate for predicting the degree of hydrolysis under any combination of values of the variables.

Protein precipitating capacity of crude canola tannins: effect of pH, tannin, and protein concentrations

Abstract: The protein precipitating capacity of canola tannins was evaluated using the protein precipitation assay of Hagerman and Butler (J. Agric. Food Chem. 1978, 26, 809−812) and the dye-labeled bovine serum albumin (BSA) assay of Asquith and Butler (J. Chem. Ecol. 1985, 11, 1535−1543). Condensed tannins were isolated from hulls of Cyclone, Excel, and Westar canola cultivars. The tannin content in the hulls ranged from 98 to 1973 mg of catechin equivalents/100 g of hulls, as determined by the vanillin assay. The effect of pH on the affinities of dye-labeled and unlabeled BSA, fetuin, gelatin, lysozyme, and pepsin was monitored. The optimum pH for the precipitation of dye-labeled and unlabeled BSA was found to be 3.5 and 4.0, respectively. The optimum pH for the precipitation of proteins was found to be 0.3−3.1 pH units below the isoelectric points of the proteins. The crude tannin extracts contained about 20% proanthocyanidins, which were soluble in ethyl acetate as determined by the vanillin assay. Canola tann...

Who is dentally anxious? Concordance between measures of dental anxiety.

Abstract: Studies of the prevalence of dental anxiety in general population samples have produced estimates which range from a low of 26% to a high of 204% It is not clear whether these reflect real differences among populations or whether they are the result of the use of different measures and different cut-off points We undertook a large scale mail survey of dental anxiety in a random sample of the adult population living in Metropolitan Toronto designed to assess the performance of and agreement between three measures These were Corah's DAS, the single item used by Milgrom and colleagues in Seattle and the ten-point fear scale used by Gatchel These measures and their published cut-off points produced prevalence estimates of 109%, 234% and 82% respectively While there was a significant association between scores on pairs of measures the agreement between them was far from perfect Kappa values ranged from 037 to 056, indicating only fair to moderate agreement beyond chance There was evidence to indicate that the dentally anxious subjects identified by each measure differed according to certain behavioural and other characteristics The results of the study suggest the need to revisit the issue of measurement in studies of dental anxiety

Optimization of Hexametaphosphate‐Assisted Extraction of Flaxseed Proteins Using Response Surface Methodology

Abstract: Total proteins of defatted low-mucilage flaxseed meals were isolated by extraction with aqueous sodium hexametaphosphate (SHMP). A composite central rotatable design was used to study effects of pH (X1), meal-to-solvent ratio (X2) and concentration of SHMP (X3) on nitrogen extractability (Y1) and protein recovery (Y2). Using RSM, quadratic polynomial equations were obtained for Y1 and Y2 by multiple regression analysis. All three variables significantly affected nitrogen solubility and protein extractability. The pH was the most effective factor and meal-to-solvent ratio was least. Verification experiments confirmed validity of predicted models. Stationary points for response surfaces were characterized as maxima and they were Y1=77.6% at X1= 8.90, X2= 1:33.6 and X3=2.75% and Y2=57.5% at X1=9.00, X2=1:33.3 and X3=2.85%, for nitrogen extractability and protein recovery, respectively.

Alternative loop rings

Abstract: Contents. Preface. Introduction. I. Alternative Rings. Fundamentals. The real quaternions and the Cayley numbers. Generalized quaternion and Cayley-Dickson algebras. Composition algebras. Tensor products. II. An Introduction to Loop Theory and to Moufang Loops. What is a loop? Inverse property loops. Moufang loops. Hamiltonian loops. Examples of Moufang loops. III. Nonassociative Loop Rings. Loop rings. Alternative loop rings. The LC property. The nucleus and centre. The norm and trace. IV. RA Loops. Basic properties of RA loops. RA loops have LC. A description of an RA loop. V. The Classification of Finite RA loops. Reduction to indecomposables. Finite indecomposable groups. Finite indecomposable RA loops. Finite RA loops of small order. VI. The Jacobson and Prime Radicals. Augmentation ideals. Radicals of abelian group rings. Radicals of loop rings. The structure of a semisimple alternative algebra. VII. Loop Algebras of Finite Indecomposable RA Loops. Primitive idempotents of commutative rational group algebras. Rational loop algebras of finite RA loops. VIII. Units in Integral Loop Rings. Trivial torsion units. Bicyclic and Bass cyclic units. Trivial units. Trivial central units. Free subgroups. IX. Isomorphisms of Integral Alternative Loop Rings. The isomorphism theorem. Inner automorphisms of alternative algebras. Automorphisms of alternative loop algebras. Some conjectures of H.J. Zassenhaus. X. Isomorphisms of Commutative Group Algebras. Some results on tensor products of fields. Semisimple abelian group algebras. Modular group algebras of abelian groups. The equivalence problem. XI. Isomorphisms of Loop Algebras of Finite RA Loops. Semisimple loop algebras. Rational loop algebras. The equivalence problem. XII. Loops of Units. Reduction to torsion loops. Group identities. The centre of the unit loop. Describing large subgroups. Examples. XIII. Idempotents and Finite Conjugacy. Central idempotents. Nilpotent elements. Finite conjugacy. Bibliography. Index. Notation.

Emerging role of technology licensing in the development of global product strategy: Conceptual framework and research propositions

Abstract: In the context of mode of entry into new markets, existing theory tends to identify technology licensing as a step toward or an alternative to wholly owned subsidiaries. However, recent trends in t...