Showing papers by "University of Guelph published in 1979"

An intermediate neglect of differential overlap theory for transition metal complexes: Fe, Co and Cu chlorides

Abstract: A complete Intermediate Neglect of Differential Overlap model suitable for the examination of transition metal complexes is described. The model is characterized by the inclusion of all the one-center exchange terms necessary for rotational invariance and accurate spectroscopic predictions, as well as an accurate description of integrals involving 3d atomic orbitals. The model is within the unrestricted Hartree-Fock formalism, and a method for spin purification is described. Problems with convergence of the self-consistent field are discussed, and a method that has been found successful in aiding the convergence is outlined. The model has been applied to many transition metal systems. In this article the results of calculations on the chlorides of Fe, Co and Cu are described. The results of these calculations are compared with experiment, and with the results of calculations by other methods.

Ground State Baryons in a Quark Model with Hyperfine Interactions

Abstract: We discuss the ground-state baryons $N$, $\ensuremath{\Lambda}$, $\ensuremath{\Sigma}$, $\ensuremath{\Xi}$, $\ensuremath{\Delta}$, ${\ensuremath{\Sigma}}^{*}$, ${\ensuremath{\Xi}}^{*}$, and $\ensuremath{\Omega}$ in a quark model with flavor-independent confinement and color hyperfine interactions. We include the effects of wave-function distortions for unequal quark masses as well as interband mixing via the hyperfine interactions and find good agreement with the observed masses.

Van der Waals model of adsorption

Abstract: A statistical-mechanical model for physical adsorption of a gas on a solid substrate is developed, based on Van der Waals' concept of dividing the interaction potential between a pair of molecules into a hard-sphere repulsive part and an infinitely weak and long-range attractive part. The interaction between the substrate and gas molecules is similarly modeled by a hard-wall repulsive potential with long-range attractive tail. For a specific choice of the intermolecular and wall-molecule attractive terms, an explicit solution is obtained for the model. This solution shows that three different classes of adsorption isotherm are possible: in class I, the adsorption is infinite in the limit that the gas pressure approaches the saturated vapor pressure, in class II the adsorption remains finite in the limit, while in class III the adsorption becomes negative in the limit. If the temperature of crossover between different classes is plotted as a function of $\frac{{\ensuremath{\epsilon}}_{w}}{\ensuremath{\alpha}}$, where ${\ensuremath{\epsilon}}_{w}$ and $\ensuremath{\alpha}$ are respectively the minimum of the wall-molecule potential and the integrated strength of intermolecular attractions, then the resulting curve has the same shape as the bulk phase coexistence curve. The model shows agreement with experimental results for the adsorption of argon, krypton, and xenon on graphite, and for argon adsorbed on xenon, as well as with recent computer-simulation results for argon adsorbed on carbon dioxide.

Charmed baryons in a quark model with hyperfine interactions

Abstract: We employ a quark model based on quantum chromodynamics and tested against noncharmed baryons to predict masses and decay rates of ground-state and excited baryons containing one charmed quark. Among other conclusions, the calculations indicate that the orbitally excited ${\ensuremath{\Lambda}}_{c}$ $\frac{1}{{2}^{\ensuremath{-}}}$ analogous to the $\ensuremath{\Lambda}(1405)$ is stable against strong decays.

Left-handers and right-handers compared on a motor task.

Abstract: Finger-tapping performance of 45 subjects of each sex and handedness combination, for a total of 180, was compared. Performance measures were speed (mean intertap interval) and regularity (standard deviation of intertap interval). Males tapped faster but not more regularly than females. The between-hand differences in performance were smaller for both measures in left-handers. When absolute magnitudes of between hand differences were compared, females showed smaller differences in regularity of tapping than males. Speed and regularity of tapping were statistically independent; both measures discriminated well between the preferred and nonpreferred hand of both handedness groups, but the differences in speed were more marked than the differences in regularity. Data on the performance of children on the same task are included for comparative purposes.

Studies on Membrane Fusion with Natural and Model Membranes

Abstract: Fusion of membranes is a common and highly important event in the biology of eukaryotic cells Membrane fusion is required for the uptake by endocytosis and the intracellular digestion of extracellular material and also for the transport of intracellular materials to the extracellular space by exocytosis The formation of endocytotic vesicles at the cell surface involves invagination of a segment of the plasma membrane, which must then fuse with itself in order to form a closed vesicle Subsequently, the digestion of the contents of the endocytotic vesicles involves a series of membrane fusion sequences between these vesicles and lysosomes and Golgi vesicles (review, Edelson and Cohn, 1978) Membrane fusion also plays a prominent role in the reverse process of exocytosis in which fusion takes place at the cell surface between the membrane of the exocytotic vesicle and the plasma membrane Exocytotic discharge is basic to the processes of cell excretion and secretion and is involved in the release of a wide variety of enzymes, hormones, and neurotransmitter substances from such cells as the newly fertilized egg, blood platelets, leukocytes, mast cells, nerve cells, cells participating in the formation of kinins, angiotensin, and erythropoietin, and hormone-producing cells in the adrenal medulla, neurohypophysis, anterior pituitary, thyroid, and pancreas (reviews, Ceccarelli et al, 1974; Douglas, 1975; Carafoli et al, 1975)

Theory of polar fluids

Abstract: The theory of fluids of polar polarizable molecules is extended using the previous formalism based on renormalization. Exact formal expressions are derived for the pressure, entropy and internal energy at three levels of renormalization. Thermodynamic perturbation theory is developed, and numerical estimates are made for polar polarizable hard spheres. The effect of the polarizability α on the Helmholtz free energy A predicted by the two renormalized versions is much larger than the prediction of the unrenormalized version, which is in essential agreement with the unrenormalized perturbation theory of McDonald. The renormalized theories predict a strong dependence on the anisotropy of α, while no such dependence is predicted by the unrenormalized theories. The numerical values and the dependence on the anisotropy of α are in good agreement with the results of the more complicated perturbation treatment of Patey and Valleau, which requires detailed knowledge of a rigid polar reference system obtainable onl...

Early ontogeny of walleye,Stizostedion vitreum, with steps of saltatory development

Abstract: Frequent in vivo observations of arbitrary stages revealed a saltatory pattern of development in the early ontogeny of fluvial spawning walleye. The requirement for an environment rich in dissolved oxygen was indicated by i) spawning site characteristics, ii) the lack of carotenoid pigments, iii) swim-up at hatching, iv) a planktonic (pelagic) existence by means of immobile surface suspension and subsequent surface swimming, and v) a poorly developed temporary embryonic respiratory system, including a subintestinal-vitelline vein, hepatic-vitelline vein and duct of Cuvier. Between the start of hatching and development of the ability to remain planktonic, the temporary embryonic respiratory system was enhanced by an increase in the proportion of the total blood volume passing through the subintestinal-vitelline vein — the largest respiratory surface. Immobile surface suspension was possible due to both the buoyancy of the large oil globule and the forces of surface tension. Also, immobile surface suspension would provide low energy transport from the fluvial spawning grounds to the lacustrine environment where zooplanktonic prey would be relatively more abundant. An intimate relationship between oil globule size (shape) and a dynamic behavioral transition (including the consumption of larger particles, cannibalism, and swimbladder inflation) suggested that energy expenditures occurring during fluvial transport were necessary for appropriate developmental synchrony.

Carbohydrate Levels and Photoassimilate Export from Leaves of Phaseolus vulgaris Exposed to Excess Cobalt, Nickel, and Zinc.

Abstract: Exposure of white bean seedlings to phytotoxic burdens of Co, Ni, or Zn reduced the export of 14C-photoassimilates from the nearly fully expanded unifoliate leaves. Little 14C reached the major sink areas, the young trifoliate leaves and the root tips, of seedlings exposed to metal. The unifoliate leaves accumulated sucrose, reducing sugars, and starch. These effects were evident within 1 or 2 days.

Mechanical and biochemical components of apparent specific dynamic action in largemouth bass, Micropterm salmoides Lacéepède

Abstract: Apparent SDA was defined as the energy expenditure associated with the ingestion of a meal. In the present study apparent SDA was equated to an increase in oxygen consumption above the postabsorptive level subsequent to the ingestion of a meal. The energy cost for physically processing a meal, mechanical SDA, was equated to the oxygen uptake associated with the ingestion of non-digestible cellulose. The energy utilized by anabolic and catabolic processes associated with the ingestion of a standard diet was identified as biochemical SDA. Apparent, mechanical and biochemical SDA were each positively related to the energy intake of the standard diet. Apparent SDA expressed relatively to energy ingested equalled 10·5% and was independent of the caloric content of the meal. Mechanical SDA increased asymptotically with ingested meal size and energy content. Relative to apparent SDA, mechanical SDA decreased with meal size, suggestive of an enhancement in efficiency. Biochemical SDA rose exponentially with increase in ingested energy, reflective of the cost for growth and catabolism.

Effect of soil properties on erosion by wash and splash

Abstract: This paper describes laboratory testing of 148 samples collected from Southern Alberta for erosion by wash and splash. Rainfall intensity was held constant during these tests. Soil aggregation was the most significant variable explaining soil loss. The significance of other soil properties, such as organic carbon and clay content is variable, depending on the interrelationships among aggregate stability, organic content, and clay content of particular soils. Variations in erodibility of the major soils examined are explained by the resistance of aggregates to compaction and dispersion. Splash detachment and wash transport are the dominant erosion mechanisms in inter-rill areas.

A simple theory regarding ambimobility of xenobiotics with special reference to the nematicide, oxamyl.

Abstract: A theory is presented to explain the phloem mobility of certain systemic xenobiotics that are not weak acids. It is shown that there is a theoretically optimum permeability that permits optimum circulation through the symplasm and apoplast (including the phloem and xylem) of Solanum tuberosum plants. The optimum permeability is large enough to permit substantial passive permeation into sieve cells in the source leaf and yet is small enough to permit phloem transport with some retention. The optimum permeability is a function of the velocity of sap flow in sieve tubes, the radius of the sieve tube, the over-all length of the plant, and the length of the carbohydrate and xenobiotic sources. It is argued that the nematicide, oxamyl, is near the optimum permeability under some experimental conditions. It is shown that depending on the strength of the carbohydrate sink in roots or growth points and depending on the permeability of the xenobiotic, there can be passive accumulation of xenobiotics in the sieve tubes in the carbohydrate sink regions.

Molecular Models for Solvent Structure at Polarizable Interfaces

Abstract: Molecular models developed to account for the dielectric properties of the polarizable metal/solution interface are reviewed. Experimental data obtained for both aqueous and non-aqueous systems in the absence of specific adsorption are examined within the context of these models. It is concluded that a relatively simple model can describe the properties of the inner layer in aprotic solvents where intermolecular forces can be described on the basis of permanent and induced dipole—dipole interactions.

EFFECT OF STORAGE TIME AND CONDITIONS ON THE HARD-TO-COOK DEFECT IN COWPEAS (Vigna unguiculata)

Abstract: Storage under unfavorable conditions is known to adversely affect the cooking quality of legumes by leading to the “hard-to-cook” defect. This phenomenon was studied by examining the texture and microstructure of Ghanainan cowpeas, variet “Adua ayera,” following storage at 0°C 80% RH; 21°C 35% RH and 29°C, 85% RH for up to 12 months. Scanning electron microscopy revealed no changes in raw beans after 12 months storage but soaking in water produced a loss of some protein bodies in seeds stored at 29°C. Texture measurement indicated that the rate of cooking of the beans decreased with increasing storage temperature and that storage at 29°C introduced the formation of the “hard-to-cook” defect. The micro structure of the defective beans showed an incomplete break down of the middle lamella which may partially explain this defect.

Lichen water relations under drying conditions

Abstract: Summary The loss of water by evaporation in various species of lichens has been examined under a range of controlled windspeed/radiation regimes. Temperate and arctic species both show a type of morphological control of evaporation. Such control varies, however, with the nature of the surrounding environment. Evaporation from those species which show a very low resistance to evaporative water loss such as Bryoria nitidula, Umbilicaria deusta and U. veiled appears to be relatively insensitive to increases in radiant flux. Conversely those species, or specific growth forms, which show a high resistance to evaporative water loss, such as Cladina stellaris and U. muhlenbergii, appear to be sensitive to increases in supply of radiant energy. These results suggest that the morphological control of evaporation in lichens is significant to the ecology of this group of plants.

The theory of saltation and its application in the ontogeny of fishes: steps and thresholds

Abstract: The view that development proceeds gradually is so engraved in our minds that any other possibility is not only treated with disbelief but viewed with distaste. Gould (1977, p. 409) put it admirably: ‘The reconciliation of our gradualistic bias with the appearance of discontinuity is a classical problem of intellectual history. We have sought to reduce the external phenomena of saltation to an underlying continuity of process to reduce the qualitative to the quantitative. Philosophies of change and progress have wrestled with this dilemma and have tried to resolve it by formulating such laws as the ‘transformation of quantity into quality’ of the Hegelian dialectic: the addition of quantitative steps will lead eventually to a qualitative leap . ..‘. It seems it is more comfortable to believe that ontogeny and phylogeny are gradual. Gradual ontogeny can be ‘proved’ by arbitrarily and leisurely sampling a sequence of stages, gradual phylogeny by expectations of finding every ‘missing link’. First, to alleviate the bad taste, I propose to talk of saltation instead of discontinuity. Saltation (Liem 1974, Ruse 1977) seems to be a better term for this phenomenon because it means ‘an advance by a leap or leaps rather than by continuous gradation’. Development is not interrupted, but merely ‘advancing in spurts’ (Webster’s New International Dictionary of the English Language, 1960). The theory was first applied to the ontogeny of fishes by Vasnetsov (1953)’ and Kryzhanovsky et al. (1953). They invented a sequence of ‘etapes’ of quantitative morphogenesis and growth, separated by a combination of brief but distinct qualitative changes in a developmental process. Brody (1945) and Martin

The 5-S RNA binding protein from yeast (Saccharomyces cerevisiae) ribosomes. Evolution of the eukaryotic 5-S RNA binding protein.

Abstract: The carboxyl-terminal half (CN2 fragment) of the yeast 5S RNA binding protein (YL3) retains an ability to form homogeneous ribonucleoprotein complexes with RNA although the N-terminal half (CN1) appears to confer specificity for the 5S RNA molecule [Nazar, R N, Yaguchi, M, Willick, G E, Rollin, C F and Roy, C (1979) Eur J Biochem 102, 573–582] The nucleic acid binding site in this fragment was more clearly delineated by cleaving the CN2 fragment with a variety of enzymatic and chemical reagents and further examining the ability of the products to form RNA-peptide complexes Hot acetic acid treatment produced a 47-residue subfragment (CN2-A1) which originated from the C terminus and continued to form stable ribonucleopeptide complexes The amino acid sequence of this subfragment was determined to be: -Pro-Ala-Phe-Lys-Pro-Thr-Glu-Lys50-Phe-Thr-Lys-Glu-Gln-Tyr-Ala-Ala-Glu60-Ser-Lys-Lys-Tyr-Arg-Gln-Thr-Lys-Leu-Ser70 -Lys-Gln-Gln-Arg-Ala-Ala-Arg-Val-Ala-Ala80-Lys-Ile-Ala-Ala-Leu-Ala-Gly-Gln-Gln-COOH, with 12 of the 16 basic residues in the CN2 fragment being present in this binding site The amino acid sequence of the CN2-A1 fragment bears a limited homology in both amino acid and charge distribution with histone 2B from mammals and with one of the 5S RNA binding proteins (EL25) from Escherichia coli The results suggest that many protein binding sites for nucleic acids may share common structural features and further support the notion that the single large eukaryotic 5S RNA protein may have evolved through a fusion of genes for the multiple 5S RNA binding proteins in prokaryotes

Distribution, community structure and production of fishes in the upper Speed River, Ontario: a preimpoundment study

Abstract: The upper Speed River, on which a dam was under construction, was surveyed through fourteen qualitative and six quantitative collections to determine the distribution of fishes in the river above Guelph, Ontario and in a tributary, Luteral Creek. At the quantitative localities the removal method was used to estimate density and standing crop of all species. At three of these localities age and growth of the dominant species were determined and total ecological production calculated.

Changes in mercury levels in harbor porpoises from the Bay of Fundy, Canada, and adjacent waters during 1969-1977.

Abstract: Mercury levels were studied in a sample of 146 harbor porpoises taken in the Bay of Fundy, Canada, and adjacent waters during 1969–77. Mean concentrations of total mercury recorded in 5-year old males (exemplifying sexually mature adults) were 1.12 ppm in axial muscle, 0.38 in cerebrum, 0.31 in cerebellum, 2.00 in kidney, and 15.7 in liver. Respective means in tissues of 5-year old females were 1.46, 0.42, 0.21 2.77 and 16.2 ppm. There was a clear correlation of increase in total Hg with age in the tissues examined. Except in the liver, mercury levels were less well correlated with weight and body length than with age. Hg levels were not significantly correlated (p > 0.05) with weight and lengthwithin age classes, except marginally in the case of liver (P ⩾0.10). Hg in muscle was virtually all in the methylated form, but in liver only about 17% was methylated. The proportions in other tissues were intermediate (kidney about 41%, mam-mary gland about 46%, brain about 8 to 52%). Levels in liver were thought to be those giving the best indication of changes in background levels of mercury in the food chain. Significant changes in Hg tissue levels appear to have occurred during the 9-year study period. Liver Hg levels in both sexes decreased from 1970 to 1971, remained low for 3 years, increased again in 1974, and continued to do so in the years following. Data are presented suggesting that this also occurred in other tissues. Since there is no evidence of a change in diet in this period, we speculate that the decline in Hg levels could be correlated with a dominance of relatively mercury-poor Gulf Stream water in the Bay of Fundy approaches in 1971–73, as opposed to the usual dominance by waters of the Nova Scotia current.

Effects of prolonged cyanide and thiocyanate feeding in rats.

Abstract: Male weanling rats were fed a semipurified diet containing 10% casein; this diet restricted in methionine, vitamin B12, and iodine; or the complete and restricted diets supplemented with either 1500 ppm potassium cyanide or 2240 ppm potassium thiocyanate for 11.5 mo. There were no deaths or clinical signs of toxicity. Cyanide, but not thiocyanate, caused a consistent reduction in weight gain in the complete and restricted groups. Both cyanide and thiocyanate caused decreased thyroid gland activity in young rats, particularly in the restricted groups. Plasma thyroxine concentrations were maintained in the mature cyanide‐treated rats, even though secretion rates were decreased. However, the mature thiocyanate‐treated animals showed decreased plasma thyroxine concentrations, despite thyroid gland enlargement. Modest primary myelin degeneration in the spinal cord white matter was found in the restricted group and in rats receiving this diet supplemented with either cyanide or thiocyanate. The lesions did not ...

Tolerance and toxicity of cobalt, copper, nickel and zinc in clones of agrostis gigantea

Abstract: SUMMARY Three clones of Agrostis gigantea were evaluated for their tolerance to cobalt, copper, nickel and zinc. Of the clones originating from a mine waste site in Sudbury, Ontario, one showed tolerance to copper, cobalt, and nickel, the other only to nickel. Neither of these clones showed tolerance to zinc. A clone from a seed supply house lacked tolerance to any of the metals tested. Copper was most toxic to A. gigantea, followed by nickel, cobalt and zinc.

Migration and spawning energetics of the anadromous sea lamprey, Petromyzon marinus

Abstract: Energy expended in migration and reproduction was determined from measurements of caloric concentration and body and gonodal weight for nontrophic sea lampreys collected from different sites along the St. John River, New Brunswick. The estimated cost of locomotion in swimming the 140 km which separates the estuary from the spawning redds was 300 and 260 kcal for males and females respectively. Acutal distance which lampreys swam as well as mean swimming speed were estimated from a linear regression equation relating energy expenditure for locomotion and body weight. Energy expenditure for breeding was considerably greater than that catabolized throughout the upstream migration.

Changes in plasma thyroxine, triiodothyronine and cortisol associated with starvation in rainbow trout (Salmo gairdneri)

Abstract: Chronically starved rainbow trout (Salmo gairdneri) showed a significant fall in liver size, total liver glycogen, liver glycogen concentration and plasma glucose levels. Liver lipid concentration did not differ significantly from controls although total liver lipid reserves fell during the first 40 days of starvation but had partly recovered after 65 days of starvation. Plasma cortisol and T3 levels did not show consistent changes concomitant with food deprivation over the 65 day period of the experiment. However, plasma T4 levels in fish starved for 40 or 65 days were significantly lower than comparably fed animals. The involvement of T4 in intermediate metabolic processes in salmonids is discussed.

Spherical harmonic expansion of the intermolecular site-site potential

Abstract: An analytic expression is given for the expansion of a site-site intermolecular potential , where u αβ is a function of the form r αβ -n , r αβ being the site-site distances, in terms of (generalized) spherical harmonics. Explicit expressions are obtained for the harmonic coefficients for the cases of linear, tetrahedral and octahedral molecules and when u αβ is the Lennard-Jones (12, 6) model. The convergence of this expansion is studied for molecules of these symmetries, and is found to be rapid in most cases provided that L*(= L/σ) is less than about 0·22, where L is the largest centre-to-site distance, and σ is the effective molecular diameter.