Showing papers by "University of Guelph published in 1984"

High-resolution PCB analysis: synthesis and chromatographic properties of all 209 PCB congeners

Abstract: The synthesis and spectroscopic properties of all the mono-, di-, tri-, tetra-, penta-, hexa-, and heptachlorobipheynls are reported and the synthesis of all 209 polychlorinated biphenyls (PCBs) is completed. The retention times and molar response factors of the 209 PCBs were determined relative to a reference standard, octachloronaphthalene. The retention times for these compounds generally increased with increasing chlorine content, and it was apparent that within a series of isomers there was an increase in retention time with increasing meta and para and decreasing ortho substitution. By use of a 50-m narrow bore fused silica capillary column coated with SE-54, it was possible to separate 187 PCB congeners, and only 11 pairs of compounds were not fully resolved. With some additional analytical improvements, isomer-specific PCB analysis can be utilized to determine the composition of commercial PCBs and accurately follow the fate and distribution of these pollutants within the global ecosystem.

Accessibility and Utilization: Geographical Perspectives on Health Care Delivery

Abstract: Geographical Perspectives on Health Care Health Care Delivery Systems Some International Comparisons Access to Health Care Physician Organization, Location and Access to Health Care Measuring the Potential Physical Accessibility of General Practitioner Services Utilization of Health Care Facilities Revealed Accessibility? Jarvis' Law and the Utilization of Mental Health Care Spatial Aspects of Health Care Planning

The effect of size and swimming speed on locomotor kinematics of rainbow trout

Abstract: 1. During swimming at constant speed the frequency ( f ), amplitude ( a ) and depth ( d ) of the tail trailing edge, and the length of the propulsive wave (λ) were measured for rainbow trout ranging in total length (L) from 5.5 to 56.0 cm. Fish were tested in a water flume using increasing velocity tests to sample a range of swimming speeds, V. 2. λ was independent of V and related to size by:λ=1.43L 0.83 so that wavelength was relatively larger in smaller fish. 3. f was related to L and V according to: f =3.19L −⅓ +1.29V/L. 4. a was independent of V but was relatively smaller in larger fish: a =0.36L 0.74 5. d was also independent of V but relatively larger in larger fish: d =0.18L 1.05 6. Thrust power (=drag power) calculated using Lighthill9s small amplitude bulk momentum model was two to three times the theoretical minimum of a flat plate of equivalent length and area moving parallel to the flow with a presumed turbulent boundary layer. 7. Froude efficiency increased with swimming speed, and it is shown that this is the usual relationship for fish studied so far. Froude efficiency was essentially independent of size at the critical swimming speed. 8. Estimated aerobic efficiency increased with size at the critical swimming speed, implying that muscle efficiency also increases with size.

Reflections on Some Decisive Events in the Early Life of Fishes

Abstract: A scholarly life-history model, applicable to various ontogenies, requires precise definitions of the major periods and their boundaries. The theory of saltatory ontogeny enables one to construct such a model based on natural boundaries between consecutive intervals of development. This theory stipulates that development does not proceed by a continuous accumulation of inconspicuous, small changes but is a sequence of rapid changes in form and function alternating with prolonged intervals (steady states) of slower development during which complex structures are prepared for the next rapid change. These times of rapid changes from one steady state to the next are called thresholds and represent decisive events of life history. Saltation explains some of the most misunderstood events of ontogeny. For example, it explains why only activation should be accepted as the beginning of ontogeny, and why insemination, fertilization, and hatching are not the appropriate clues for timing ontogeny. Similarly,...

Light-cone gauge in Yang-Mills theory

Abstract: A prescription for massless Feynman integrals in the light-cone gauge ${n}_{\ensuremath{\mu}}{A}_{\ensuremath{\mu}}^{a}=0$, ${n}^{2}=0$, is suggested which leads to well-defined and exact, but Lorentz-noninvariant, integrals. As a result the Yang-Mills self-energy is likewise Lorentz noninvariant, but remains transverse in agreement with the Ward and Becchi-Rouet-Stora (BRS) identities. It is also shown that the assumption of Lorentz invariance of the integrals, coupled with the validity of the Ward (BRS) identity, leads to a nonlocal Yang-Mills self-energy.

Ecomorphological analysis of fish taxocenes in rainforest streams of northern Borneo

Abstract: Average species richness for fish taxocenes in the Nida River (Poland), Grand River (Ontario) and Baram River (Sarawak, Malaysia) was 7, 16 and 24 species respectively. Discriminant analysis of 15 morphological attributes indicated Baram fishes partitioned the habitat vertically into mainly surface, pelagic, benthic and substratum niche types. Attribute comparisons among the river systems revealed a progression towards more sedentary benthic morphologies with increasing average species richness. Similarly, niche compression as a consequence of increasing average species richness was indicated by a reduction in length of life and average size, and was associated with development of complex life-history and reproductive styles. Total niche space occupied by the fish taxocenes was comparable in the three river systems despite differences in species richness. The amount of species packing and niche space occupied by Baram fish taxocenes were also not related to the numbers of species present. Fish community structure was apparently determined by the range of available resources and the associated specializations of the coexisting species.

Bluefin tuna warm their viscera during digestion

Abstract: Acoustic telemetry showed that stomach temperature from large bluefin tuna, Thunnus thynnus, held in an impoundment, changes markedly during feeding. The stomach cools rapidly on ingesting cold food. It then warms to a maximum of 10–15 °C above water temperature over a period of 12–20 h. Temperature decreases slowly over the next 20–30 h to a final state where it remains 3–6 °C above water temperature. The viscera are thermally isolated. Conductive heat losses are reduced by an overlying gas bladder and by the thick fatty muscle of the body wall. Convective heat losses are prevented by heat exchangers in the circulation. The temperature rise can be accounted for by heat released in the hydrolytic processes of digestion and by an increase in metabolic rate. The elevated temperatures should speed digestion and allow the tuna to feed frequently when food is abundant.

Alteration and recovery of bleeding times, platelet aggregation and fatty acid composition of individual phospholipids in platelets of human subjects receiving a supplement of cod-liver oil

Abstract: The effect of supplementation with cod-liver oil containing eicosapentaenoic acid (EPA), 20∶5ω3, on bleeding times, thrombin-induced platelet aggregation, platelet protein, platelet cholesterol, and the level and fatty acid composition of individual phospholipids in the platelets of human subjects was determined. Measurement of these parameters was conducted before the subjects received the supplement (day 0), after they received the supplement for 14 days (day 14), and 14 days after the supplement was terminated (day 28) so as to monitor recovery. The mean bleeding times exhibited a marked increase (by 81%) with supplementation and returned to near basal (day 0) values within 14 days after the supplement was terminated. Cod-liver oil supplementation significantly reduced thrombin-induced platelet aggregation with a partial recovery being exhibited by day 28. The content of phospholipid, cholesterol and protein (μg/109 platelets) was not significantly different (P>0.05) when isolated from the subjects at day 0, 14 and 28, as neither were the composition of individual phospholipids [phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI) and sphingomyelin (SPH)] given as % of total phospholipid. However, the fatty acid compositions of all platelet phospholipids were altered significantly by the fish oil supplement. In PC, EPA rose from 0.3 to 2.9% of total fatty acids and docosahexaenoate from 0.7 to 1.8% concomitant with a drop in arachidonate (from 14.1 to 9.6%) and linoleate (from 10.2 to 7.9%); these levels approached basal levels 14 days after supplementation was terminated. The highest percentage of EPA with supplementation was found in PE (4.3%), while the arachidonate fell from 38.8 to 30.5%, with low percentages of EPA occurring in PS (0.7%) and PI (0.5%). The level of 24∶1 in SPH increased significantly (from 17.8 to 24.8) with supplementation and reverted to basal values by day 28. These results suggest a close relationship of the observed fatty acid changes in individual platelet phospholipids to the altered hematological parameters and platelet-vessel wall interactions produced by cod-liver oil supplementation.

Acclimation to High CO2 in Bean Carbonic Anhydrase and Ribulose Bisphosphate Carboxylase

Abstract: Young bean plants (Phaseolus vulgaris L. cv Seafarer) grew faster in air enriched with CO2 (1200 microliters per liter) than in ambient CO2 (330 microliters per liter). However, by 7 days when increases in overall growth (dry weight, leaf area) were visible, there was a significant decline (about 25%) in the leaf mineral content (N, P, K, Ca, Mg) and a drop in the activity of two enzymes of carbon fixation, carbonic anhydrase and ribulose 1,5-bisphosphate (RuBP) carboxylase under high CO2. Although the activity of neither enzyme was altered in young, expanding leaves during the acclimation period, in mature leaves the activity of carbonic anhydrase was reduced 95% compared with a decline of 50% in ambient CO2. The drop in RuBP carboxylase was less extreme with 40% of the initial activity retained in the high CO2 compared with 50% in the ambient atmosphere. While CO2 enrichment might alter the flow of carbon into the glycolate pathway by modifying the activities of carbonic anhydrase or RuBP carboxylase, there is no early change in the ability of photosynthetic tissue to oxidize glycolate to CO2.

Discrimination of the number three by a raccoon (Procyon lotor)

Abstract: This paper reports the establishment of a discrimination based upon the number three in a male raccoon. Following a 6-month training period, the subject was able to select a clear Plexiglas cube containing 3 objects (grapes or small metal bells) from an array of cubes containing 1, 2, 3, 4, and 5 items. The results confirm previous reports of “intelligence” in the raccoon, and extend the number of species in which sensitivity to number has been demonstrated (see review by Davis & Memmott, 1982).

The stabilizing role of bonding agents on the entrainment of sediment by wind

Abstract: Well sorted fine sand pretreated with varying concentrations of two soluble salts (MgCl2 and CaCl2) was tested for threshold shear velocity in a recirculating wind tunnel. These tests demonstrate that even relatively low surface salt concentrations can significantly increase threshold shear velocity. However, the relationships between surface salt concentration and threshold shear velocity for the two salts were not significantly different, which is similar to the results for monovalent chlorides presented by Nickling & Ecclestone. A general relationship between threshold shear velocity and total, surface soluble salt content is presented.

Textural and Microstructural Changes in Corn Starch as a Function of Extrusion Variables

Abstract: The effect of extrusion variables (temperature, feed moisture and screw speed) on the expansion, breaking strength and microstructure of starch extrudates was studied using response surface methodology. For expansion the most significant variable was found to be feed moisture which bore an inverse relation to the expansion response. All the extrusion variables studied were significantly related to expansion and accounted for 95.7% of the total variation. Screw speed and feed moisture were the most significant variables for breaking strength, all three variables accounting for 89.7% of the total break strength variation. Microstructure of the extrudates could be related to the extrusion variables, the expansion and breaking strength responses. The porosity of the extrudates increased with decreasing moisture, with a concomitant increase in expansion and a decrease in breaking strength. Regression equations generated from composite rotatable response surface design experiments could be used to accurately predict the responses studied.

Tryptophan requirement of the 2.5-kg piglet determined by the oxidation of an indicator amino acid.

Abstract: The tryptophan requirement of 2.5-kg piglets was measured by the oxidation of L-[1-14C]phenylalanine or DL-[1-14C]lysine when meals containing various levels of L-tryptophan were offered. Increasing dietary tryptophan from 0.65 to 2.0 g/kg decreased 14CO2 release from L-[1-14C]phenylalanine but further increases in dietary tryptophan level resulted in no further decrease in 14CO2 output. Regression analysis, with a crossover model, showed phenylalanine oxidation was minimized with a dietary tryptophan level of 1.94 g/kg (95% confidence limits 1.93 to 1.95). The oxidation of lysine was also reduced by increasing tryptophan levels to 2 g/kg; as tryptophan level was increased to 3 g/kg there was no statistically significant reduction of lysine oxidation. These studies suggest that the dietary tryptophan requirement of the 2.5-kg piglet is no more than 2 g/kg of a 240 g protein per kilogram diet.

Energy transfer and female condition in nursing harp seals Phoca groenlandica

Abstract: Lactating female harp seals, most with their pups, were collected on the “whelping” ice in the Gulf of St. Lawrence in 1976 and from 1978 to 1980. During lactation females lost weight at an average rate of 3.17±0.52 (SEb) kg d−1, for a total energy loss of approximately 250000 kcal. Pups grew at a mean rate of 2.78±0.19 kg d−1 for a gain in production energy of about 194000 kcal. Compared to 1976, adult females sampled in 1978 to 1980 had lower energy reserves at the onset of lactation. Coincidentally there has been a decrease in newborn lengths and girths. Although compensatory growth in weight appears to occur, between-year differences in newborn lengths persist to weaning. Various reproductive strategies of female harp seals faced with reduced energy stores are discussed.

Unusual organization and lack of recombination in the ribosomal RNA genes of Coprinus cinereus.

Abstract: We find three interesting characteristics of the genes encoding the ribosomal RNA (rRNA) in the basidiomycete Coprinus cinereus. First, there are only 60 to 90 copies of the genes, fewer than in other fungi. Second, the genes are organized in an unusual arrangement. The 5S rRNA genes are located in the repeat unit which encodes the other rRNAs and all four rRNAs are transcribed in the same direction. Third, meiotic recombination is inhibited within the ribosomal DNA.

Energy flow and the vertical structure of real ecosystems.

Abstract: Three possible explanations for the well-known limitation of food chain lengths to two or three links for the most part are subjected to an empirical test, using the fact that ectotherms, especially invertebrates, tend to have higher production efficiencies than endotherms. The data are consistent with the hypothesis that food chain lengths are limited by the availability of energy.

PIXE analysis of thick targets

Abstract: A review of thick-target PIXE is presented. Particular attention is paid to the relative efficacies of various methods of calibration, to achievable detection limits and to various experimental factors which affect analytical accuracy.

Development of the caruncular and intercaruncular regions in the bovine endometrium.

Abstract: Uterine specimens from fetal and postnatal heifers were examined by various types of microscopy to determine when the endometrium differentiated into caruncular and intercaruncular regions and changes in the cell types as the uterus developed. The luminal surface of the fetal uterus was formed into prominent pedunculated or mushroom-shaped nodules. Glandular development was first observed at about 250 days of gestation as short invaginations of the epithelium of the internodular surface adjacent to nodular stalks. The basal profile of each epithelial cell in the deeper portions of developing glands formed cytoplasmic processes which extended into the stroma. Between birth and 3 months of age there was a tremendous increase in the glandular epithelium. Concurrent thickening of the connective tissue component caused expansion of the nodular peduncle and a gradual flattening of the nodule until, by 1 year of age, only slight elevations remained, with a discrete caruncle visible on each. By following the development of the glandular component it was concluded that only the apical portion of each fetal nodule will develop into a caruncle and the sides of the nodule, together with the internodular portion, are destined to be the intercaruncular region.