Showing papers by "University of British Columbia published in 1972"

Paraglacial Sedimentation: A Consideration of Fluvial Processes Conditioned by Glaciation

Abstract: Glaciation is schematically considered as a perturbation of “normal” fluvial conditions. Drift is unstable in a proglacial or postglacial fluvial environment, resulting in heightened sediment movement that continues as long as drift material remains easily accessible for fluvial erosion and transportation. Sediment yield bears no relation to concurrent primary production of weathered debris. Examples of such “paraglacial” denudation and sedimentation are reported from two contrasting areas. Postglacial valley alluvial deposits are widespread in central Baffin Island where rapid sedimentation continues today; estimated denudation rates are an order of magnitude higher than in comparable unperturbed areas. In south-central British Columbia, rapid sedimentation during the paraglacial period contrasts sharply with present-day conditions.

Oceanic fine structure

Abstract: Measurements by free fall instruments, in the San Diego Trough, the Florida Current, and the central Pacific, reveal the detailed structure of the vertical component of the oceanic temperature gradient. The temperature changes are concentrated into regions on the order of a meter thick wherein the measured gradients are often more than ten times the average gradient. The horizontal extent of the regions of high gradient is greater than 750 meters in the seasonal thermocline off San Diego, but is only a few hundred meters at depths greater than 400 meters. Fine scale measurements show that the layers of high gradient consist of even finer fluctuations in gradient which are only a few centimeters thick. Time scales of the thinnest of these regions of high gradient are of the order of five minutes. The data also yields an estimate of the entropy generation. According to the results of an idealized model relating entropy generation to the turbulent heat transport, only 240 to 700 ergs per cm.2 per se...

X-ray photoelectron spectroscopy of copper compounds

Abstract: The X-ray photoelectron spectra of some forty-six copper compounds and complexes have been measured. The chemical shifts obtained from accurate determinations of the binding energies have been qualitatively explained on the basis of the Pauling electronegativity concept using the group electronegatives of Huheey for the polyatomic counter anions. The chemical shifts of the copper atoms as well as the atoms in the ligands were found to be dependent not only on the oxidation state but also on the kind and number of ligand atoms. Intense satellite lines were found in the 2p and 2s bands of the cupric compounds; the number and splitting of the satellites were found to be sensitive to the chemical environment. A correlation was found between the satellite splitting and the binding energies and this is explained by a 3d→4s, 4p ‘shake-up’ mechanism.

Generalization of the Einstein Theory

Abstract: The assumption that ${{T}^{\ensuremath{ u}}}_{\ensuremath{\mu};\ensuremath{ u}}=0$ in curved space-time is questioned. Field equations are given which are consistent with the assumption ${{T}^{\ensuremath{ u}}}_{\ensuremath{\mu};\ensuremath{ u}}=\ensuremath{\lambda}{R}_{,\ensuremath{\mu}}$, and which reduce to the Einstein equations when $\ensuremath{\lambda}=0$. The equations are equivalent to the Einstein equations in empty space-time, but differ from them in the presence of matter. Applications to cosmology, stellar structure, and collapsing objects are suggested.

Locations of amino acids in brain slices from the rat. Tetrodotoxin-sensitive release of amino acids.

Abstract: 1. Amino acids, particularly glutamate, γ-aminobutyrate, aspartate and glycine, were released from rat brain slices on incubation with protoveratrine (especially in a Ca2+-deficient medium) or with ouabain or in the absence of glucose. Release was partially or wholly suppressed by tetrodotoxin. 2. Tetrodotoxin did not affect the release of glutamine under various incubation conditions, nor did protoveratrine accelerate it. 3. Protoveratrine caused an increased rate of formation of glutamine in incubated brain slices. 4. Increased K+ in the incubation medium caused release of γ-aminobutyrate, the process being partly suppressed by tetrodotoxin. 5. Incubation of brain slices in a glucose-free medium led to increased production of aspartate and to diminished tissue contents of glutamates, glutamine and glycine. 6. Use of tetrodotoxin to suppress the release of amino acids from neurons in slices caused by the joint action of protoveratrine and ouabain (the latter being added to diminish reuptake of amino acids), it was shown that the major pools of glutamate, aspartate, glycine, serine and probably γ-aminobutyrate are in the neurons. 7. The major pool of glutamine lies not in the neurons but in the glia. 8. The tricarboxylic cycle inhibitors, fluoroacetate and malonate, exerted different effects on amino acid contents in, and on amino acid release from, brain slices incubated in the presence of protoveratrine. Fluoroacetate (3mm) diminished the content of glutamine, increased that of glutamate and γ-aminobutyrate and did not affect respiration. Malonate (2mm) diminished aspartate and γ-aminobutyrate content, suppressed respiration and did not affect glutamine content. It is suggested that malonate acts mainly on the neurons, and that fluoroacetate acts mainly on the glia, at the concentrations quoted. 9. Glutamine was more effective than glutamate as a precursor of γ-aminobutyrate. 10. It is suggested that glutamate released from neurons is partly taken up by glia and converted there into glutamine. This is returned to the neurons where it is hydrolysed and converted into glutamate and γ-aminobutyrate.

Invertebrate facultative anaerobiosis.

Abstract: The unique pattern of anaerobic carbohydrate metabolism in invertebrate facultative anaerobes serves to couple other substrate-level phosphorylations to the glycolytic reactions, thus increasing the potential yield of high-energy phosphate compounds. Currently, two important coupling sites can be identified:

The world of underground ice

Abstract: Underground ice is restricted to permafrost areas where its distribution is sporadic and often unpredictable. A knowledge of the distribution and abundance of underground ice is essential to northern development, because a variety of man induced disturbances can cause underground ice to thaw, often with serious consequences. The criteria for a classification of the principal types of underground ice are the source of the water prior to freezing and the processes which transfer water to the freezing plane. The origin of massive icy bodies in the Western Arctic of North America is explained by a water expulsion theory. The excess water now found in the icy bodies is attributed to water expelled from coarse textured sediments by the downward growth of permafrost. The suggested mechanism is illustrated by three pingos which have grown since 1950. The role of glaciation in the formation of relic offshore permafrost in relatively shallow Arctic coastal areas is examined. The evidence suggests that offs...

Substitutional solution hardening of magnesium single crystals

Abstract: Single crystals of magnesium containing varying amounts of In, Al, Pb and Bi in solid solution have been deformed in tension over a range of temperature between 4.2°k and 500°k. The critical resolved shear stress (CRSS) for basal slip has been examined in the light of the existing solution hardening theories. The earlier published data on Zn, Cd, Tl and Li solutes were included in arriving at a generalized solution hardening model for magnesium. The CRSS in the plateau region (above 295°k) can be described best with a C 2/3 relationship, where C is the atom fraction of solute. The strengthening mechanism was found to be one involving the interaction of solute atoms with edge dislocations. The extent of hardening is determined by the size and valency differences between the solute and the solvent. The valency term was found equivalent to the modulus interaction term of the statistical solution hardening theories. The CRSS at 0°k increases linearly with alloying at concentrations of solute above 0....

Optimal Power System Stabilization Through Excitation and/or Governor Control

Abstract: For an optimal linear regulator design a performance function of the quadratic form must be chosen. The question arises of how to decide the weighting matrix Q of the performance function. A new method is developed in this paper to determine Q in conjunction with a left shift of the dominant eigenvalues as far as the practical controllers permit. The method is then applied to the optimal control design of a typical power system. Three cases are investigated, the first with an optimal excitation control uE, the second with optimal governor controls uG and uG, with and without the dash-pot, and the third with uE plus uG control. The stabilizing signals thus obtained are given nonlinear tests on the same power system. It is found from the results that the optimal controls are more effective than conventional excitation control, that the optimal governor control without dash-pot is just as good as the optimal excitation control, and that the optimal uE plus uG control is the best way to stabilize a power system.

Diffusion-controlled precipitate growth in ternary systems I

Abstract: Diffusion-controlled precipitation in isothermal ternary systems of arbitrary constitution is analyzed theoretically. The treatment is applicable to isolated precipitates whose morphology is preserved during growth;i.e., planar surfaces, cylinders, spheres, spheroids, and ellipsoids. The analysis does not account for ternary diffusional interaction. For a particular bulk alloy composition, the problem is essentially to determine the precipitatematrix interface velocity and the phase diagram tie-line which defines the equilibrium concentrations at this interface. The concepts of interface composition and interface velocity contours on the ternary phase diagram are introduced as instruments for solution of this problem. The influence on these contours of various diffusivity ratios for the independent components and of precipitate morphology is investigated. The assumption that local equilibrium maintains at the precipitate-matrix interface is critically examined and it is suggested that there are many instances in which the assumption is invalid. Therefore, Hultgren’s concept of paraequilibrium is discussed and is incorporated into the present theoretical framework. The techniques developed in the analysis are applied to ferrite growth in the Fe-C-Mn system.

Ridged Fields and Associated Features in Southern Campeche: New Perspectives on the Lowland Maya

Abstract: Prehistoric ridged fields and canals were recognized from the air in 1968 along the Candelaria River of Campeche, Mexico, in the vicinity of sites described by E. Willys Andrews in 1943. These remains were subsequently identified by Scholes and Roys as the settlements of Acalan, a native province along the route of the journey by Cortes to Honduras. Ground exploration in 1969 and 1970 has suggested that the fields were used over a considerable period of time under a system of diversified horticulture. The extensive canal system apparently provided access from the rivers to firm ground and allowed shortcuts and bypasses alongside the rivers themselves. The landscape suggests a considerable prehistoric population, vigorously engaged in major public works projects over a large area. It invites further integrated investigation of its past human ecology, particularly for information on variants of basic Lowland Maya subsistence patterns and the new perspectives this may give on the structure, success and demise of this civilization. An earlier version of this paper was read at the 39th International Congress of Americanists in Lima, 1970.

Observations on human monocyte kinetics after pulse labeling.

Abstract: Monocyte kinetics were studied in seven hematologically normal individuals using in vivo pulse labeling with tritiated thymidine. Although occasional labeled cells appear in the peripheral blood within 4 or 5 hr of the administration of label, a significant outflow from the marrow begins 13–26 hr later. This interval is occupied by the G2 and M phases of the mitotic cycle since mitotic cells are not observed in the peripheral blood. The duration of the DNA synthesis phase of monocytes is measured at 34 hr ≈ 1.8 hr. Cells do not enter this phase while circulating since exposure of circulating cells to tritiated thymidine does not result in any uptake. If monocytes are not ‘end’cells which have completed their mitotic activity before leaving the marrow they must at least be inhibited from further proliferative activity until they are permanently sequestered in other tissues. The generation time is probably not less than 40 hr and data derived from the mean grain counts of labeled cells suggest that it is often more than 70 hr. The total daily output of monocytes in man is 9.4 × 108 cells per 24 hr ≈ 3.3 × 108. Cells leave the bloodstream with a half-time of about 71 hr thereby proving themselves to be considerably more durable than neutrophils which have a half-life in the neighborhood of 6 hr.

Axonal transport in nigro-striatal and nigro-thalamic neurons: effects of medial forebrain bundle lesions and 6-hydroxydopamine.

Abstract: —Axonal transport was studied in two efferent projections of the substantia nigra: (1) the nigro-striatal system; and (2) the nigro-thalamic system [14C]leucine was injected stereotaxically into the left substantia nigra of rats At various intervals thereafter significant amounts of [14C]protein were found in the midbrain (which surrounded the injection site), hypothalamus, thalamus and corpus striatum on the injected side of the brain By determining the temporal characteristics of the distribution of [14C]protein, axonal transport from the substantia nigra to the thalamus and corpus striatum could be inferred Fast (approximately 50 mm/day) and slow (approximately 1 mm/day) rates of flow were evident in both systems Either electrolytic lesions of the medial forebrain bundle or intraventricular pretreatment with 6-hydroxydopamine (200 μg) produced a substantial decrease in the amount of labelled protein reaching the corpus striatum but not in that reaching the thalamus The decrease following electrolytic lesions correlated significantly with the decrease in the activity of striatal tyrosine hydroxylase, but after 6-hydroxydopamine the decrease in axonal transport was consistently less than the loss of striatal tyrosine hydroxylase This difference indicated that a portion (perhaps as much as 20 per cent) of the nigro-striatal neurons are non-catecholaminergic Finally, we present data which suggest that in contrast to effects on peripheral neurons, 6-hydroxydopamine destroys the cell bodies as well as nerve terminals of adrenergic neurons in the central nervous system

Physicochemical effects of aldehydes on the human erythrocyte.

Abstract: The effects of formaldehyde, acetaldehyde, and glutaraldehyde on human red blood cells were investigated. It was found that (a) The surface negative charge of the erythrocytes at pH 7 was increased 10% by glutaraldehyde, but not by the other two aldehydes. (b) The effect of incomplete fixation of the red blood cells was demonstrated by hemoglobin leakage studies The leakage of hemoglobin subsequent to formaldehyde treatment was especially pronounced Acetaldehyde-fixed cells showed some leakage of hemoglobin after an hour of exposure to the fixative, whereas glutaraldehyde-fixed cells showed no hemoglobin leakage. (c) All three aldehydes caused K+ leakage during fixation. The concentrations of K+ in the fixing solutions all reached the same level, but whereas the leakage with glutaraldehyde was immediate, that with formaldehyde was more gradual and that with acetaldehyde reached a steady state only after 24 hr. (d) The effects of the aldehydes on red cell deformability and swelling revealed that glutaraldehyde hardened the cells within 15 min, formaldehyde within 5 hr, while acetaldehyde required at least 24 hr to produce appreciable fixation. (e) The hematocrit changes accompanying the fixation process depended upon cell volume changes and loss of deformability.

Microscale pressure fluctuations measured within the lower atmospheric boundary layer

Abstract: Eulerian measurements of microscale fluctuations in static pressure are used, in conjunction with measurements of air velocity, to describe some of the properties of the static pressure fluctuations that occur within the turbulent flow of the lower atmospheric boundary layer. Using an instrument developed to measure the static pressure at a point within the boundary layer, data were collected at heights ranging from the surface up to about 6 m. The results are presented as power spectra, cross-spectra, coherence and phase. For all observations over a flat boundary the root-mean-square pressure produced by the boundary-layer turbulence is about 2.6 times the mean stress. The pressure spectra are found to have a, well-defined shape which does not change with height above the surface; at the higher frequencies the spectra show a power-law behaviour with a mean slope of −1·7. A number of observations with two pressure sensors are used to describe the structure and propagation velocity of individual pressure pulses.A dominant feature of the pressure-velocity relationship is that the large-scale pressure fluctuations are approximately in phase with the downstream velocity fluctuations; at small scales there is a large phase difference (∼−135°). These phase differences are interpreted to be the result of interaction of the large pressure-producing scales with the earth's surface, the small scales being ‘free’ of the surface. Prom the simultaneous measurements of pressure and downstream velocity the effect of pressure forces on the energy flux out of the downstream velocity fluctuations was evaluated. Typical values are about 0-45 of the net energy source to the downstream component. By means of pressure and vertical velocity measurements an estimate of the pressure divergence term in the net energy budget of a boundary layer is made. It was found to be about 1/10 of the energy feeding term.