Showing papers by "Memorial University of Newfoundland published in 1985"

Dietary factors and the incidence of cancer of the stomach

Abstract: A case-control study of diet and stomach cancer was conducted during 1979-1982 in Toronto, Winnipeg, and St. John's Canada. Two hundred forty-six histologically verified cancer cases were individually matched by age, sex, and area of residence to 246 randomly selected population controls. Daily nutrient consumption values were calculated from quantitative diet history questionnaire data through use of the US Department of Agriculture Food Composition Data Bank, which was extended and modified for Canadian items. For the analysis, continuous conditional logistic regression methods were used. It was found that consumption of dietary fiber was associated with decreased risk of gastric cancer; the odds ratio estimate of trend was 0.40/10 g average daily intake of fiber (i.e., 0.40(1.5)/15 g, etc.) (p less than 10(-8)). Also, average daily consumption of nitrite, chocolate, and carbohydrate was associated with increasing trends in risk, with odds ratio estimates, respectively, 2.6/mg (p less than 10(-4)), 1.8/10 g (p less than 10(-4)), and 1.5/100 g (p = 0.015). While citrus fruit intake appeared to be somewhat protective (odds ratio = 0.75/100 g daily average, p = 0.0056), vitamin C intake was less so, and vitamin E not at all. Thus, a number of dietary components seem to be implicated in the pathogenesis of stomach cancer.

Self-similar condensation of spherically symmetric self-gravitating isothermal gas clouds

Abstract: The authors show that similarity solutions for the condensation of spherically symmetric self-gravitating isothermal gas clouds are much more abundant than was hitherto believed; they have discovered that each of the discrete solutions found by previous authors must be replaced by a bounded two-parameter continuum of such solutions. Moreover, the two parameters (z0, w0) admit a clear and useful physical interpretation. z0 characterizes the asymptotic form of a solution as t→-∞ (i.e. at very early times), and reflects how intrinsically unstable against contraction the cloud interior is from the outset. w0 characterizes the asymptotic form of a solution as t→+∞ (i.e. at very late times) and reflects how important external pressure is in driving compression. The evolution of the flow is presented and discussed.

Optimal algorithms for comparing trees with labeled leaves

Abstract: LetR n denote the set of rooted trees withn leaves in which: the leaves are labeled by the integers in {1, ...,n}; and among interior vertices only the root may have degree two. Associated with each interior vertexv in such a tree is the subset, orcluster, of leaf labels in the subtree rooted atv. Cluster {1, ...,n} is calledtrivial. Clusters are used in quantitative measures of similarity, dissimilarity and consensus among trees. For anyk trees inR n , thestrict consensus tree C(T 1, ...,T k ) is that tree inR n containing exactly those clusters common to every one of thek trees. Similarity between treesT 1 andT 2 inR n is measured by the numberS(T 1,T 2) of nontrivial clusters in bothT 1 andT 2; dissimilarity, by the numberD(T 1,T 2) of clusters inT 1 orT 2 but not in both. Algorithms are known to computeC(T 1, ...,T k ) inO(kn 2) time, andS(T 1,T 2) andD(T 1,T 2) inO(n 2) time. I propose a special representation of the clusters of any treeT R n , one that permits testing in constant time whether a given cluster exists inT. I describe algorithms that exploit this representation to computeC(T 1, ...,T k ) inO(kn) time, andS(T 1,T 2) andD(T 1,T 2) inO(n) time. These algorithms are optimal in a technical sense. They enable well-known indices of consensus between two trees to be computed inO(n) time. All these results apply as well to comparable problems involving unrooted trees with labeled leaves.

Contained (reflected) turbidity currents from the Middle Ordovician Cloridorme Formation, Quebec, Canada: an alternative to the antidune hypothesis

Abstract: The parautochthonous Cloridorme Formation is a syn-orogenic flysch succession that was deposited in an elongate foredeep basin as mainly lower middle-fan, outer-fan, and basin-floor deposits. The basin-floor deposits (about 1.5 km thick) are confined to members β1, β2 and γ1, and are characterized by graded, thick (1–10 m) mud-rich calcareous greywacke beds previously interpreted as deposits of concentrated, muddy, unidirectional turbidity currents that locally generated backset (antidune) lamination in internally stratified flows. The dominant flow directions were from east to west, but west to east transport also occurred, as seen in the orientation of ripples, climbing ripples, flutes, consistently overturned flames, and grain imbrication. We believe that the flows that deposited these thick calcareous greywacke beds reversed by roughly 180° one or more times during deposition of the lower sandy part of the beds. Flow reversals are consistent with the sharp grain-size breaks and mud partings within sandy divisions. Measurement of grain fabric relative to stratification in the most celebrated ‘antidune’ bedforms indicates flow from west to east; thus, the bedforms were produced by west-to-east migration of megaripples, not by the upcurrent migration of antidunes. The thick muddy beds were deposited by large-volume, muddy flows that were deflected and reflected from the side slopes and internal topographic highs of a confined basin floor, much like the ‘Contessa’ and similar beds of the Italian Apennines. Large quantities of suspended mud were ponded above the irregular basin floor and settled to produce the thick silty mudstone caps seen on each bed. Because of their mode of emplacement, we propose that these beds be called contained turbidites.

Diving Depths of Four Alcids

Abstract: -Incidental catches of 12,243 Common Murres (Uria aalge), 875 Atlantic Puffins (Fratercula arctica), 36 Black Guillemots (Cepphus grylle), and 9 Razorbills (Alca torda) were recorded off Newfoundland during the summers of 1980-1982 (26,445 net-days of fishing effort). Most catch occurred in stationary gill nets set on the sea floor at depths of up to 180 m and revealed that murres, Razorbills, puffins, and guillemots can dive to depths of at least 180, 120, 60, and 50 m, respectively. Diving ability appeared to be directly correlated with body size. Received 5 March 1984, accepted 2 June 1984. LITTLE is known about the depths to which alcids and other aquatic birds are capable of diving (Kooyman 1975). Using depth recorders, Kooyman (1975) and Kooyman et al. (1982) established that Emperor (Aptenodytes forsteri) and King (A. patagonica) penguins can dive to depths in excess of 240 m. Although penguins are probably the best underwater swimmers among the ten families of diving birds, Kooyman (1975) suggested that "If most other birds can descend and ascend at similar rates (e.g. 2 m/s) then a 180 m 'bounce' dive is probably within the range of most diving birds ." properly adapted for the extreme conditions found at those depths. As Northern Hemisphere ecological counterparts to penguins, alcids are morphologically similar. They exploit similar prey, such as euphausiids, squid, and small schooling fishes (Bedard 1969, Kooyman 1975). All pursue prey underwater using partly folded wings to propel themselves (Bedard 1969), and numerous adaptations for underwater "flight" and feeding have evolved in the Alcidae (Storer 1952, Stettenheim 1959, Bedard 1969, Spring 1971). Studies of diets (Tuck and Squires 1955, Belopol'skii 1957) and a few records of catches in fishing gear (Tuck 1961) imply that alcids sometimes forage near the ocean bottom at considerable depths, but there are no detailed accounts of diving ability or estimates of maximum diving depths. In Newfoundland, thousands of alcids, particularly Common Murres (Uria aalge) and Atlantic Puffins (Fratercula arctica), drown each year in surface-set salmon (Salmo salar) and bottom-set cod (Gadus morhua) gill nets as they forage for capelin (Mallotus villosus) in waters intensively fished by man (Piatt et al. 1984). Net-mortality is acute during the one-month period that capelin form large, dense spawning schools inshore. We have accumulated detailed data on 912 incidents involving 13,163 alcids caught in gill nets. These data suggest that the diving abilities of different alcid species differ markedly and that the maximum diving depths attainable by alcids have been considerably underestimated (e.g. Stettenheim 1959, Pearson 1968, Kooyman 1975). STUDY AREA AND METHODS During the summers of 1980-1982, 39 inshore fishermen from communities adjacent to 7 major seabird colonies in Newfoundland (Wadham, Penguin, Cabot, Funk, and Baccalieu islands, Witless Bay, and Cape St. Mary's) recorded daily seabird catches with details on the depths and locations of net entrapment (Piatt et al. 1984). Cod gill nets were positioned on the sea floor at varying depths up to 180 m. The bulk of inshore fishing effort occurs at depths of less than 60 m, and only 5% of fishing effort observed in our study occurred at greater depths. On about 30 occasions John F. Piatt accompanied fishermen at sea and observed fishing techniques and removal of seabirds caught in nets retrieved from depths of up to 180 m. In addition, several thousand net-drowned alcids brought in to fishing wharves were examined, and over one thousand were autopsied to determine sex, age, and stomach contents.

The genetics of Graves' disease: HLA and disease susceptibility.

Abstract: To relate genetic variation in Graves' disease (GD) susceptibility to polymorphism at MHC loci, clinical and family studies were undertaken in eastern Hungary. Among 1980 relatives of 534 index patients, 2.9% of siblings, 2.7% of offspring, and 3.0% of parents had GD. HLA haplotype combinations in affected sibling pairs were determined in the present data and combined with data in the literature (12 sibling pairs from Farid 1981, 12 from Chan et al. 1980, and 15 from Sasazuki et al. 1983); 43, 23, and 1 affected sibling pairs shared, respectively, 2, 1, and 0 HLA haplotypes. This distribution is inconsistent with simple dominant inheritance, but is consistent with simple recessive inheritance of HLA-related susceptibility over a range of gene frequencies (0.2-0.4). A frequency of 0.3 gives the best fit and is consistent with penetrance of 7.1% for the recessive susceptibility genotype; the data, however, can accommodate penetrance values up to 16%. The distribution of HLA haplotypes in 33 families related disease susceptibility more strongly to DR than to other loci. The distribution of HLA-B8 genotypes in 256 patients was in close agreement with Hardy-Weinberg equilibrium proportions, also favoring recessive inheritance of MHC-related susceptibility. The probability that an individual will be affected with GD can be predicted, based on sex, HLA genotype, and family history. For example, 14.9% of DR3-positive women with an affected first degree relative are likely to be affected. These predictions can be tested as family data accumulate.

High School Students' Understanding of Food Webs: Identification of a Learning Hierarchy and Related Misconceptions.

Abstract: Developing an understanding of the nature of food webs is an important topic in today's biology curricula. The relationships represented in a food web are rule-like in nature. Hence, it should be possible to construct a learning hierarchy for this concept. A hierarchy leading to the ability to determine how a change in the size of one population can affect another population in the same web but not on the same chain was hypothesized. Data from 200 subjects were extremely consistent with the hierarchy. A second major focus related to the identification of specific misconceptions held by subjects for food webs. The need to identify students' misconceptions of important concepts has been expressed widely in the recent science education literature. In the present article, an argument is presented for the usefulness of learning hierarchies in this work. Specific misconceptions and the frequencies of their occurrence are reported.

Predictive value of cord blood IgE in the development of atopic disease and role of breast‐feeding in its prevention

Abstract: The predictive value of cord blood IgE in the development of atopic disease was evaluated in a prospective study of two groups of infants. Total serum IgE level was greater than or equal to 0.7 U/ml in 44.3% of the infants with positive family history of atopy and in 16.0% among those with negative family history. The level of cord blood IgE correlated significantly with the subsequent development of atopic disease in both groups. Cord blood IgE higher than 0.7 U/ml was associated with a high risk of development of atopic eczema and wheezing, 52.8% and 58.8% respectively in the groups with or without family history of atopy; compared with 13.4% and 1.1% in the groups with IgE levels less than 0.7 U/ml. Among newborns fed exclusively on breast milk for a minimum of 3 months, the incidence of eczema and wheezing was significantly lower (12%) compared with findings in the formula-fed group (32%).

Organic storage of CO2 on the continental slope off the mid-Atlantic bight, the southeastern Bering Sea, and the Peru coast

Abstract: A comparison is made of organic content, sedimentation rates derived from 14C and 210Pb analyses, 13C and 15N isotope ratios, amorphous silica, particle size, and calcium carbonate within sediments from slopes off the mid-Atlantic bight, the southeastern Bering Sea, and the Peru coast. These sediments are mainly marine, diatom-rich, and about one-third of the organic carbon is recent, reflecting a possible transient of shelf export in response to man's increased activities since the industrial revolution. Using a combination of sedimentation and mixing rates of carbon, the C:N ratio of sediments within the upper 50 cm, and the amount of nitrogen thought to be released from the coastal zone, independent estimates suggest a carbon loading to world slopes of ∼0.3 to 0.5 × 109 tons C y−1. The Bering slope exhibits no anthropogenic transients, however, while increased carbon loading may have occurred off Peru in response to overfishing and off the mid-Atlantic bight in response to eutrophication. The generality of our results depends on which of the three systems is most representative of world slopes.

Biological and granulometric controls on sedimentary organic matter of an intertidal mudflat

Abstract: A variety of measures of organic matter concentration and quality were made on samples collected from the top few mm of intertidal mudflat sediment over the course of a year, in order to assess the relative importance of biological and sedimentological influences on sedimentary organic matter. Winter and summer were times of relatively fine-grained sediment accumulation, caused by biological deposition or stabilization processes and resulting in higher organic matter concentrations. Stable carbon isotope and Br:C ratios indicated a planktonic source of bulk organic matter. Ratios of organic carbon to specific surface area of the sediments were consistent with an organic monolayer coverage of sediment grains. Correction for changing grain size during the year showed no change in the organic concentration per unit surface area, in spite of organic matter inputs by in situ primary production, buildup of heterotroph biomass and mucus coatings, and biodeposition of organic-rich seston. There were also no indications of changes in bulk organic quality, measured as hydrolyzable carbohydrates and amino acids, in response to these biological processes. It is concluded that biological processes on a seasonal time scale affect the bulk organic matter of these sediments via a modulation of grain size rather than creation or decay of organic matter.

Structural relationships among happiness scales: A second order factorial study

Abstract: Our intent in this study was to investigate structural relationships among happiness scales, and to determine whether the happiness construct could be represented adequately by a single score index. Second order principal factors analyses were computed on six data sets representing eight samples of subjects where the variables were comprised of global or sub-global indices of happiness. Single factor solutions were obtained from every analysis. The findings were interpreted as, (1) supporting a hierarchical, rather than an orthogonal multicomponent, model of relationships among happiness scales and, (2) indicating that the construct can be represented adequately by a single score index in social indicators research.

Plasma vitellogenin in landlocked atlantic salmon (Salmo salar ouananiche): isolation, homologous radioimmunoassay and immunological cross-reactivity with vitellogenin from other teleosts☆☆☆

Abstract: Vitellogenin was isolated by affinity chromatography and gel filtration from landlocked Atlantic salmon plasma. Vitellogenin was labelled with iodine-131 using iodogen and an homologous radioimmunoassay was developed. There was poor immunological cross-reactivity with vitellogenin or plasma from other teleosts. Parallelism of the vitellogenin standard to the displacement by plasma of vitellogenic salmon allowed the assay to be used to evaluate the seasonal concentration profile of vitellogenin in female adult salmon. Extracts of liver or ovary from female Atlantic salmon also yielded displacements parallel to the vitellogenin standard in the assay.

Erosion and deposition of fine‐grained sediments from the Bay of Fundy

Abstract: Simulations of the erosion, transport and deposition of fine-grained sediment, such as that of Greenberg & Amos and the Hydraulics Research Station, have illustrated a general lack of reliable field data. Consequently, some standard equations and constants used in modelling the sedimentation character of fine-grained cohesive sediment were evaluated based on data from two field studies and a flume experiment with undisturbed sediment from the Bay of Fundy. Initial results showed that the resistance to erosion of intertidal fine-grained sediment is controlled largely by the degree of subaerial exposure and the consequent dehydration and compaction. The sediment shear strength was high (4 kPa), but generally decreased seawards across the intertidal zone. The resistance of intertidal mud to erosion can be 80 times greater than sub-tidal counterparts. The rate of sediment erosion varied as a complex function of the applied bottom shear stress. At stresses immediately above the critical, the erosion rate decreased asymptotically with time. At higher excess stresses, the erosion rate was linear with respect to time. Thus sediment erosion cannot be represented by a single coefficient. The Krone method of computing sedimentation rates of suspended material was shown, by comparisons with direct measurement, to overpredict by 29%. All variables used in his method were measured in the evaluation with the exception of the critical deposition stress (TJ. The closest comparisons were obtained when T~ was assigned a value of 0.1 N m-’ following Creutzberg & Postma. m s-’). However, the settling tube measures of settling rate, compared to in situ results, underpredicted particle settling by an order of magnitude (2.7 x m s- I). The reason for this discrepancy is not apparent from our results. The in situ still-water particle settling rate (V,) was constant with respect to time (2.1 x

Promising applications of neodymium boron Iron magnets in electrical machines

Abstract: Neodymium Boron Iron (N d BF e ) magnets have high energy product with suitable magnetic and physical properties for applications in electrical machines. The design aspects of permanent magnet machines using NdBFe magnets are presented. The ranges of applications cover both generators and motors up to 200 kW ratings. The exciting combination with micro-computers and power electronics makes the permanent magnet motors truly attractive for drives requiring smooth synchronous operation, constant torque and constant power characteristics.

Structures of shorthorn sculpin antifreeze polypeptides

Abstract: The amino acid sequences of the two major antifreeze polypeptides (AFP) from the shorthorn sculpin have been determined using an automatic protein sequencer and enzymic digestion. These two polypeptides, SS-3 and SS-8, consist of 33 and 45 amino acid residues respectively. The N-terminal methionyl residue is blocked in both the polypeptides. When aligned for maximum structural similarity these two AFP are 80% homologous, and there appears a deletion of 12 amino acid residues at the N-terminal portion of SS-3. Like the winter flounder AFP, both the sculpin AFP also contain the 11-amino-acid repeat sequences. The secondary structure of the sculpin AFP is mainly α-helical as deduced from circular dichroic spectral data. The helical content of SS-8 is high (73%), while that SS-3 is moderate (about 45%). The latter exhibits a relatively weak antifreeze activity. Removal of the blocked N-terminal residue in SS-8 did not alter the helical content significantly but did reduce the antifreeze activity. Helical contents of proteolytically generated fragments of AFP are much lower, and they are devoid of activity. The α-helix in the SS-8 component is seen to be amphiphilic in character. The relevance of this feature to the mechanism of the antifreeze action is briefly discussed.

Structure in temperate predaceous diving beetle communities (Coleoptera: Dytiscidae)

Abstract: Collection records of adult dytiscid beetles (Coleoptera, Dytiscidae) from 312 sites within the province of Alberta, Canada, were analyzed for patterns of similarity in species distribution. Sites compared on the basis of species occurrence (Jaccard coefficient of similarity and group average cluster analysis) separated into 12 principal clusters, interpreted as communities. However, cluster inclusion occurred at very low levels of similarity and 30% of sites were unclustered outliers. Ecological charade us tics of sites that were recognized as varying between dusters were salinity, productivity, stability, water temperature, substrate type, flow and vegetation. An index relating these qualitatively defined variables to species numbers is presented. An analysis of co-occurrence patterns of species was conducted as an alternative approach to definition of multispecies associations. Each possible combination of co-occurrence between pairs of species occurring in more than 5 collections each was tested for significance (p = 0.005) by means of Yates corrected χ2 tests. Results of tests were expressed in binary terms, blank – no significance, x - significant. Species were then clustered on the basis of patterns of significant co-occurrences as above. This analysis was used as the basis for ordination of species in a symmetrical matrix with species ordered so as to maximize density of points of significant co-occurrence (x) around the principal diagonal. Areas in the matrix showing high densities of co-occurrence were interpreted as representing communities. The cluster analysis of species produced a better cluster pattern than obtained for sites but while generally similar, the species clustering pattern was less fine. The principal species groups consisted of those of saline water, alpine/subalpine lotic sites, other lotic habitats, and lentic habitats with two subgroups, species in forest areas and grassland species. The ordination, while reflecting this grouping of species, demonstrated that each group graded into others through loss of certain species and acquisition of others and thus showed the continuum nature of these communities. Restricting ordination to congeneric species indicated that these do not usually show identical patterns of co-occurrence but neither are patterns coincident with mutual exclusion. Within genera, considerable overlap in occurrence between species is the norm but species tend to occupy slightly different positions relative to one another along qualitatively defined ecological gradients. Relative position of species in these ordinations shows good correlation with patterns of geographical distribution lending support to the interpretation of ordination patterns reflecting relative ecological segregation. The dytiscid beetle fauna of north temperate regions is especially rich. Also, the large number of significant co-occurrences observed between species shows that species packing in many habitats of this region is dense. It is speculated that this species richness is possible because of the seasonality of habitats at these latitudes which reduces competition and predation from other groups and produces seasonal pulses of high productivity permitting a species rich fauna to develop because of abundant resources. It is likely that factors other than interspecific competition for resources are important in shaping dytiscid communities in habitats with strong nutrient pulses.

The Philosophical Basis of Observation in Science and Science Education.

Abstract: Observation plays a fundamental role in scientific investigation. Scientific observation sometimes involves relatively simple activities requiring little preparation and unsophisticated interpretation. At other times, however, scientific observation is an extremely complex activity, indeed among the most challenging enterprises in which human beings engage. The science education field typically portrays only that segment of scientific observation at the simple end of this spectrum. In doing this, there is a risk that students will acquire a distorted image of scientific observation, and develop observational skills which are not at all adequate for the role which observation plays in science. An alternative account of observation in science is presented and its implications for science teaching are discussed.

Chemical composition and postmortem changes in soft textured muscle from intensely feeding atlantic cod (gadius morhua, l)

Abstract: Soft textured fillets from postspawning Atlantic cod caught during the influx of capelin exhibited significantly more drip than fillets from fish caught at other times of the 1983 inshore fishing season. The extent and rate of pH decline, protein, collagen and temperature of the muscle were not distinctive in fish caught during the influx of capelin. The muscle from these fish were unique in exhibiting a rapid and relatively low ultimate pH together with a stable pH after the onset of rigor mortis. The number of capelin present in the stomach of cod at the time of catch was positively related (r = 0.92) to the amount of free drip recovered from the fillets.