Showing papers by "University of British Columbia published in 1973"
TL;DR: In this article, the authors demonstrate the relationship existing between the size of a village, town or city and the magnitude of the urban heat island it produces by analyzing data gathered by automobile traverses in 10 settlements on the St. Lawrence Lowland, whose populations range from 1000 to 2 million inhabitants.
1,938 citations
TL;DR: The general economic analysis of a biological resource presented in this article suggests that overexploitation in the physical sense of reduced productivity may result from not one, but two social conditions: common-property competitive exploitation on the one hand, and private-property maximization of profits on the other.
Abstract: The general economic analysis of a biological resource presented in this article suggests that overexploitation in the physical sense of reduced productivity may result from not one, but two social conditions: common-property competitive exploitation on the one hand, and private-property maximization of profits on the other. For populations that are economically valuable but possess low reproductive capacities, either condition may lead even to the extinction of the population. In view of the likelihood of private firms adopting high rates of discount, the conservation of renewable resources would appear to require continual public surveillance and control of the physical yield and the condition of the stocks.
545 citations
TL;DR: The literature concerning the physiology and biochemistry of the enzyme phenylalanine ammonia lyase (PAL) (E.C. 4.1.1) from different organisms has been reviewed as mentioned in this paper.
445 citations
423 citations
TL;DR: It is concluded that population fluctuations in Microtus in southern Indiana are produced by a syndrome of changes in birth and death rates similar to that found in other species of voles and lemmings, and the prevention of dispersal changes the quality of the populations in the enclosures in comparison to those outside the fence.
Abstract: We conclude that population fluctuations in Microtus in southern Indiana are produced by a syndrome of changes in birth and death rates similar to that found in other species of voles and lemmings. The mechanisms which cause the changes in birth and death rates are demolished by fencing the population so that no dispersal can occur. Dispersal thus seems critical for population regulation in Microtus. Because most dispersal occurs during the increase phase of the population cycle and there is little dispersal during the decline phase, dispersal is not directly related to population density. Hence the quality of dispersing animals must be important, and we have found one case of increased dispersal tendency by one genotype. The failure of population regulation of Microtus in enclosed areas requires an explanation by any hypothesis attempting to explain population cycles in small rodents. It might be suggested that the fence changed the predation pressure on the enclosed populations. However, the fence was only 2 feet (0.6 meter) high and did not stop the entrance of foxes, weasels, shrews, or avian predators. A striking feature was that the habitat in the enclosures quickly recovered from complete devastation by the start of the spring growing season. Obviously the habitat and food quality were sufficient to support Microtus populations of abnormally high densities, and recovery of the habitat was sufficiently quick that the introduction of new animals to these enclosed areas resulted in another population explosion. Finally, hypotheses of population regulation by social stress must account for the finding that Microtus can exist at densities several times greater than normal without "stress" taking an obvious toll. We hypothesize that the prevention of dispersal changes the quality of the populations in the enclosures in comparison to those outside the fence. Voles forced to remain in an overcrowded fenced population do not suffer high mortality rates and continue to reproduce at abnormally high densities until starvation overtakes them. The initial behavioral interactions associated with crowding do not seem sufficient to cause voles to die in situ. What happens to animals during the population decline? Our studies have not answered this question. The animals did not appear to disperse, but it is possible that the method we used to measure dispersal (movement into a vacant habitat) missed a large segment of dispersing voles which did not remain in the vacant area but kept on moving. Perhaps the dispersal during the increase phase of the population cycle is a colonization type of dispersal, and the animals taking part in it are likely to stay in a new habitat, while during the population decline dispersal is a pathological response to high density, and the animals are not attracted to settling even in a vacant habitat. The alternative to this suggestion is that animals are dying in situ during the decline because of physiological or genetically determined behavioral stress. Thus the fencing of a population prevents the change in rates of survival and reproduction, from high rates in the increase phase to low rates in the decline phase, and the fenced populations resemble "mouse plagues." A possible explanation is that the differential dispersal of animals during the phase of increase causes the quality of the voles remaining at peak densities in wild populations to be different from the quality of voles at much higher densities in enclosures. Increased sensitivity to density in Microtus could cause the decline of wild populations at densities lower than those reached by fenced populations in which selection through dispersal has been prevented. Fencing might also alter the social interactions among Microtus in other ways that are not understood. The analysis of colonizing species by MacArthur and Wilson (27) can be applied to our studies of dispersal in populations of Microtus. Groups of organisms with good dispersal and colonizing ability are called r strategists because they have high reproductive potential and are able to exploit a new environment rapidly. Dispersing voles seem to be r strategists. Young females in breeding condition were over-represented in dispersing female Microtus (17). The Tf(C)/Tf(E) females, which were more common among dispersers during the phase of population increase (Fig. 6), also have a slight reproductive advantage over the other Tf genotypes (19). Thus in Microtus populations the animals with the highest reproductive potential, the r strategists, are dispersing. The segment of the population which remains behind after the selection-via-dispersal are those individuals which are less influenced by increasing population densities. These are the individuals which maximize use of the habitat, the K strategists in MacArthur and Wilson's terminology, or voles selected for spacing behavior. Thus we can describe population cycles in Microtus in the same theoretical framework as colonizing species on islands. Our work on Microtus is consistent with the hypothesis of genetic and behavioral effects proposed by Chitty (6) (Fig. 7) in that it shows both behavioral differences in males during the phases of population fluctuation and periods of strong genetic selection. The greatest gaps in our knowledge are in the area of genetic-behavioral interactions which are most difficult to measure. We have no information on the heritability of aggressive behavior in voles. The pathways by which behavioral events are translated into physiological changes which affect reproduction and growth have been carefully analyzed by Christian and his associates (28) for rodents in laboratory situations, but the application of these findings to the complex field events described above remains to be done. Several experiments are suggested by our work. First, other populations of other rodent species should increase to abnormal densities if enclosed in a large fenced area (29). We need to find situations in which this prediction is not fulfilled. Island populations may be an important source of material for such an experiment (30). Second, if one-way exit doors were provided from a fenced area, normal population regulation through dispersal should occur. This experiment would provide another method by which dispersers could be identified. Third, if dispersal were prevented after a population reached peak densities, a normal decline phase should occur. This prediction is based on the assumption that dispersal during the increase phase is sufficient to ensure the decline phase 1 or 2 years later. All these experiments are concerned with the dispersal factor, and our work on Microtus can be summarized by the admonition: study dispersal.
353 citations
TL;DR: In this paper, several possible solutions to the problem of creeping flow relative to an isolated permeable sphere are discussed and compared quantitatively, and the most satisfactory solutions are based upon Brinkman's extension of Darcy's Law.
334 citations
TL;DR: In this paper, the authors show that the observed data does not satisfy the hypothesis of consistency of the decision-maker's true 0 under the constraint pTxi < 1 for i = 1, 2,..., I where pi is a given N dimensional vector which has positive components.
Abstract: Suppose that we can observe a number of decisions xi (where xi is a non-negative N dimensional vector for i = 1, 2, ..., I) which some decision-making unit has made and let us further suppose that each vector of decisions xi satisfies a linear constraint of the form pTxi < 1 for i = 1, 2, ..., I where pi is a given N dimensional vector which has positive components.3 Given the above framework, we may ask the following question: is the observed set of decisions {xi} consistent with the hypothesis that the decision-maker chose decision xi (for i = 1, 2, ..., I) because it maximized a real valued function of N variables, ., subject to the constraint pTx < 1? A related question is how may we use the observed data {pi; xi} i = 1, 2, ..., I in order to construct an approximation to the decision-maker's true 0, assuming that such a b exists. In Section 3 below, we will give an answer to the above two questions by using the observed data {pi; xi} to construct the coefficients of a linear programming problem [4]. If this linear programme has a positive solution, then it turns out that the observed data does not satisfy the hypothesis of consistency. If on the other hand, the objective function of the linear programme has a solution equal to zero, then we may use the solution to the linear programme to construct a real valued function 0 such that for i = 1, 2, ..., I the vector xi is a solution to the following constrained maximization problem:
330 citations
TL;DR: Improved methods for rearing and screening large numbers of flies permitted the recovery of 10 mutations exhibiting a reversible temperature-dependent adult paralysis among 1.1×106 flies tested as mentioned in this paper.
Abstract: Improved methods for rearing and screening large numbers of flies permitted the recovery of 10 mutations exhibiting a reversible temperature-dependent adult paralysis among 1.1×106 flies tested. Of the 10 mutations, two were allelic to para
ts,two were alleles in a new locus, stoned (stn), and six fell into a third area, the shibire (shi) locus. Several of the shi alleles cause embryonic, larval and adult paralysis at 29° C as well as structural anomalies of various tissues. In addition to the ts mutations, several non-conditional mutations affecting adult movement were recovered.
330 citations
TL;DR: In this article, an error in the significance test associated with a rotational vector procedure for analysis of axial orientation data is pointed out and explained; an alternative approach already well established in the geologic literature, which does not require that sense be assigned to the axial data, is discussed; the results of the application of both methods to 36 till fabrics are compared.
Abstract: An error in the significance test associated with a rotational vector procedure for analysis of axial orientation data is pointed out and explained. An alternative approach already well established in the geologic literature, which does not require that sense be assigned to the axial data, is discussed; the results of the application of both methods to 36 till fabrics are compared. It is concluded that the alternative approach is superior because it is statistically sound and more efficient with regard to computer time required; it also provides more information about the fabric than does the rotational vector procedure.
319 citations
TL;DR: In this article, the authors show that functional separability restrictions on a function are equivalent to certain equality restrictions on the Allen partial elasticities of substitution, which is a way of characterizing a functional relationship.
Abstract: The literature on functional relationships among economic variables has treated elasticities of substitution and functional separability as distinct ways of characterizing a functional relationship. Discussions of elasticities of substitution have primarily been related to comparative statics analyses of the derived demand for factors of production and changes in factor shares or the derived demand for commodities and changes in budget shares.3 On the other hand, discussions of the internal structure of functions have typically been concerned with whether a function of many arguments could be separated into subfunctions. If such separability is permissible, efficiency in production or consumption can be realized by sequential optimization. For example, in production decisions relative factor intensities can be optimized within each separable subset, and then optimal intensities can be attained by holding fixed the within-subset intensities and optimizing the betweensubset intensities.4 The purpose of this paper is to integrate the discussions of functional separability and elasticities of substitution. In the context of production theory we prove theorems which establish that separability restrictions on a function are equivalent to certain equality restrictions on the Allen partial elasticities of substitution. Since Leontief [14], [15] has related functional separability to the existence of sub-aggregate indexes, our theorems relate restrictions on the Allen partial elasticities of substitution to functional separability and the existence of sub-aggregate indexes.
319 citations
TL;DR: In this article, the authors prove two basic if elementary results related to the theory of automorphic forms for GL2, local and global, and there is no immediate connection between them, but they were both suggested by some results of Atkin and Lehner and Ogg [7] in the classical theory of modular forms.
Abstract: In this Paper I shall prove two basic if elementary results related to the theory of automorphic forms for GL2. One is local and the other global, and there is no immediate connection between them, but they were both suggested by some results of Atkin and Lehner [1] and Ogg [7] in the classical theory of modular forms. They are both formulated and proved in terms of group representations, and in fact the proofs are easy pickings from Jacquet-Langlands [4]. In the last Section I shall outline the relationships between these two theorems and the results of [1] and [7]. Most of this is probably well known, but it may be useful to have it expressed, once, in print. The final few remarks pose what seems to me to be one of the fundamental questions in the subject, which deserves to be better known. Partial generalizations by Miyake of the classical results mentioned were the immediate spur to this paper. Roughly at the same time, and independently, Miyake found essentially the same results ([6]). His proofs, especially for his equivalent form of the global theorem, are fairly close to the ones given here, but follow Weil [11] rather than the methods of representations. The proof of Theorem 2 follows a suggestion of Langlands'. My own original idea (which I did not follow up in detail) was considerably more complicated, although perhaps eventually capable of yielding a refinement, it involved a generalization of a result of Rankin's (see [8] or [9]). I shall use the terminology of [4] generally, but not always, without explicit reference.
TL;DR: The results suggest that the lateral hypothalamic syndrome may to a large extent reflect the interruption of the dopaminergic nigro-striatal system and that other as yet unknown factors may also contribute to this syndrome.
TL;DR: Gamma-aminobutyric acid uptake into slices of caudate-putamen, globus pallidus and substantia nigra was studied and points to the possible existence of a pallido-nigral pathway whose neurotransmitter is GABA.
01 Aug 1973
TL;DR: In this paper, the thermophoretic velocity, vth, was related to the particle and liquid properties by an expression similar to Epstein's gas equation: V th =-0.26 kμ 2k+k p ρT ▽T.
Abstract: Experimental evidence of thermophoresis in liquids is reported for 1.011 and 0.790 μm latex spheres in water and n-hexane. The thermophoretic velocity, vth, was related to the particle and liquid properties by an expression similar to Epstein's gas equation: V th =-0.26 kμ 2k+k p ρT ▽T .
01 Jan 1973
TL;DR: Four hypotheses concerning mechanisms which might be of general importance in the behavior of predators are discussed: hunting by searching image, hunting by expectation, area-restricted search, and “niche” hunting.
Abstract: In this paper, I discuss four hypotheses concerning mechanisms which might be of general importance in the behavior of predators: hunting by searching image, hunting by expectation, area-restricted search, and “niche” hunting. In addition, I review briefly two approaches which have been taken in studying predator behavior at a more general level: experimental component analysis and optimal foraging theory. I make no attempt to review comprehensively the literature on behavior of predators.
TL;DR: In this article, a model describing the time-dependent modification of the upper mixed layer of the ocean by meteorological influences is developed, where turbulent mixing and the radiative heating within the mixed layer are expressed so that only simple parameters available from routine meteorological measurements are required as input.
Abstract: A model describing the time-dependent modification of the upper mixed layer of the ocean by meteorological influences is developed. The turbulent mixing and the radiative heating within the mixed layer are expressed so that only simple parameters available from routine meteorological measurements are required as input. The model is sensitive to the rate of production by the wind stress of energy available for mixing, and to the rate of absorption with depth of the solar radiation. Analytic and numerical results of the model for conditions of large constant winds and typical summer heating are consistent with laboratory results. The mixing response to a wind normally distributed in time is also presented. Finally, the model simulates the physical behavior of the upper mixed layer in response to diurnally varying heating: results for several different values of wind speed indicate that, even in low winds and typical summer heating, the daily fluctuations in sea surface temperature in the open ocean...
TL;DR: In this article, an iterative procedure for determining near optimal frequencies of production for the products and the associated fundamental cycle time is presented, which can be used directly for constructing production schedules.
Abstract: Most of the procedures that have been developed to find solutions to the single-machine, multi-product lot scheduling problem depend on judgment to define the desirable frequencies of production for the products. In this paper we describe an iterative procedure for directly determining near optimal frequencies of production for the products and the associated fundamental cycle time which, in many cases, can be used directly for constructing production schedules. In cases where feasible schedules cannot be constructed using the values from the iterative procedure, the procedure provides a basis for changing the production frequencies and the fundamental cycle time to obtain feasible schedules.
TL;DR: Intracranial self-stimulation data support the hypothesis that both dopaminergic and noradrenergic systems subserve positive reinforcement.
Abstract: Intracranial self-stimulation was elicited from electrodes located in either the lateral hypothalamus or substantia nigra of the rat. Facilitatory effects of d- and l-isomers of amphetamine on self-stimulation were assessed. The d-isomer was seven to ten times more effective than the l-isomer at the hypothalamic placement, whereas the two isomers were equipotent for substantia nigra electrodes. These data support the hypothesis that both dopaminergic and noradrenergic systems subserve positive reinforcement.
TL;DR: The developmental properties of shibirets1 allowed us to make a number of observations concerning determination and pattern formation and to conclude that the lesion affects a fundamental cell process common to many cell types.
TL;DR: The purpose of this investigation was to re-examine the measures of algebraic error, absolute error (AE), and within-S variance (VE) in an attempt to arrive at unambiguous definitions regarding the statistical and logical meanings of these three performance variables.
Abstract: School of Physical Education and Recreation The University of British Columbia The purpose of this investigation was to re-examine the measures of algebraic error (CE), absolute error (AE), and within-S variance (VE). in an attempt to arrive at unambiguous definitions regarding the statistical and logical meanings of these three performance variables. Under the assumption of a normal distribution, the statistic AE is completely dependent on CE and VE and thus can be predicted from them. This shows that all information contained in the term AE is contained in either CE (when the ratio CE/VE > 2.0), or in VE (when CE ≅ 0.0) or in a weighted combination of both CE and VE (when 0
TL;DR: In this paper, the slip plane has been identified as {1011} and twinning is associated with increasing flow stress with temperature, high strain-rate sensitivity, low work-hardening rate and absence of yield drop.
TL;DR: In this article, time-series observations of the upper mixed layer of the ocean are presented for a six-week period at Ocean Station Papa in the northeast Pacific Ocean, which indicate the rate and extent of the wind-induced deepening of the mixed layer during the passage of several weather disturbances.
Abstract: Time-series observations of the upper mixed layer of the ocean are presented for a six-week period at Ocean Station Papa in the northeast Pacific Ocean. These observations indicate the rate and extent of the wind-induced deepening of the mixed layer during the passage of several weather disturbances. The formation of the shallow layer of warm water that occurs under conditions of low winds and intense solar heating is also evident. A numerical model, developed by Denman, accurately predicts the behavior of the upper ocean during a 12-day period for which observed values of wind speed, solar radiation, and back radiation are used as input. To obtain realistic results, a value of 0.0012 for the ratio of the potential energy increase of the water column to the downward transfer rate of turbulent energy by the wind stress is used. This value is in agreement with that obtained from previous laboratory experiments (0.0015) indicating that the results obtained from such experiments are transferable to o...
TL;DR: In this paper, the number of fixed collectors required to sample the volume and cation content of throughfall precipitation in the coastal forests of British Columbia was examined by means of data from 134 collectors for throughfall volume and 83 collectors for chemistry.
Abstract: The number of fixed collectors required to sample the volume and cation content of throughfall precipitation in the coastal forests of British Columbia was examined by means of data from 134 collectors for throughfall volume and 83 collectors for throughfall chemistry. The relative heterogeneity of throughfall parameters in four forest plant associations was also examined. It was concluded that a sampling network suitable for quantifying throughfall volume will be inadequate for quantifying throughfall chemical parameters because of the far greater spatial variability of the latter. This variability is compounded if the study area includes more than one forest plant association. The fixed—collector method was found to be far from ideal for accurate studies of the role of leaching a nutrient cycling because of the excessive number of collectors required. An analysis of the suitability of Wilm's method of roving collectors and Attiwill's modification thereof as alternatives indicated that Wilm's method is inapplicable to studies of throughfall chemistry, but that Attiwill's modification might permit a worthwhile reduction in the number of collectors required in some studies, especially those concerned with gross, long—term studies of leaching. Attiwill's method shares many of the drawbacks of Wilm's method, however, and will probably be unsuitable for many studies. The variability of the chemical data was greatest when expressed as concentrations. Conversion to kg/ha did reduce standard deviations somewhat, although the reduction was modest on all but the most highly variable study area. Sampling at longer intervals did not result in any reduction in the standard deviations of mean throughfall cation concentrations: the effect of longer collection periods on the data expressed as kg/ha was to increase standard deviations significantly. Weekly or more frequent collections are recommended for detailed studies of throughfall chemistry.
TL;DR: The salivary gland of the ixodid tick, Dermacentor andersoni, can be induced to secrete fluid for at least 6 h when bathed in an artificial medium in vitro, and it is proposed that fluid secretion may be dependent on a Na-K activated ‘pump ATPase’, which is somehow involved in cation secretion.
Abstract: 1. The salivary gland of the ixodid tick, Dermacentor andersoni , can be induced to secrete fluid for at least 6 h when bathed in an artificial medium in vitro .
2. Fluid secretion appears to be a consequence of active Cl secretion since ( a ) it is inhibited by 95% when nitrate and by 100% when acetate replaces Cl in the bathing medium; however, bromide can support secretion as well as Cl, ( b ) the rates of fluid and Cl secretion are linearly related to the concentration of Cl in the medium; and ( c ) the S/H ratio for Cl is greater than unity at all concentrations despite a transacinar P.D. of 35 mV (lumen negative).
3. Although (in the presence of Na) a low concentration of K in the bathing medium stimulates the rate of fluid secretion fivefold, higher concentrations of K inhibit fluid secretion. The latter is largely due to a direct effect of K ion and not simply to increased osmotic pressure or reduced Na concentration. Fluid secretion is completely in hibited by 10-6 M ouabain. On the basis of these observations we propose that fluid secretion may be dependent on a Na-K activated ‘pump ATPase’, which is somehow involved in cation secretion. The S/H ratios of Na and K are greater than unity at all medium concentrations.
4. The saliva secreted in vitro is slightly hypo-osmotic to the bathing medium over a wide range of medium concentration (300-920 mOsm/l). We postulate that the primary saliva is iso- or hyper-osmotic to the bathing medium; the final elaborated saliva is probably rendered hypo-osmotic by a process of solute reabsorption somewhere between the acini and the orifice of the main salivary duct.
TL;DR: In this article, it was shown that the mechanism of basal slip involves recombination of extended dislocations lying on the prism planes followed by cross slip, and the critical resolved shear stress for basal slip was found to be temperature and strain rate dependent.
TL;DR: In this article, the effect of superplastic deformation on the grain growth kinetics was studied using both constant crosahead speed and creep tests, the grain size was measured as a function of deformation time and strain over a wide range of strain rates.
TL;DR: The data support the hypotheses that a descending gabaminergic path exists with nerve endings in the nigra, and that striatal cholinergic neurons are predominantly short axon and intra-striatal in character.
TL;DR: The findings support the concept that complete or severe deficiency of G..-6-P.D. may affect both red-blood-cell survival and white- Blood-cell function and express with the combined picture of haemolytic anaemia and mild chronic granulomatous disease.
TL;DR: The size of phytoplankton species present in the ocean may be in part determined by environmental and DVSioloeical factors as demonstrated with two phyto-ankters, DityZum brightwellii and Cokblithu~ huxleyi as mentioned in this paper.
Abstract: The size of phytoplankton species present in the ocean may be in part determined by environmental and Dhvsioloeical factors as demonstrated with two phytoplankters, DityZum brightwellii and Cokblithu~ huxleyi.
TL;DR: It was concluded that these Chromatographie forms are homogeneic † , the difference between them being the extent of the modification of one nucleotide.