Showing papers by "University of Victoria published in 1974"

Solution of an overdetermined system of equations in the l1 norm [F4]

Abstract: Submittal of an algorithm for consideration for publication in Communications of the ACM implies unrestricted use of the algorithm within a computer is permissible. General permission to republish, but not for profit, all or part of this material is granted provided that ACM's copyright notice is given and that reference is made to the publication, to its date of issue, and to the fact that reprinting privileges were granted by permission of the Association for Computing Machinery. Description The algorithm calculates an l~ solution to an overdetermined system of rn linear equations in n unknowns, i.e. the algorithm determines a vector x = {xy} which minimizes the sum of the absolute values of the residuals e(x) = ~'~i~l [ b~-~'-~i~l aij xy I. A typical application of the algorithm is that of solving the linear l~ data fitting problem. Suppose that data consisting of m points with coordinates (t~, yd is to be approximated by a linear approximating function c~l~,~ (t) + c~,~ (t) + .-. + a,~ (t) in the l, norm. This is equivalent to finding an l~ solution to the system of linear equations ~=i 4~i (t~)c~s = Y~ for i = 1, 2 ..... m. If the data contains some wild points (i.e. values of the dependent variable that are very inaccurate compared to the overall accuracy of the data), it is advisable to calculate an ll approximation rather than an/2 (least-squares) approximation, or an 1~ approximation. The algorithm is a modification of the simplex method of linear programming applied to the primal formulation of the/1 problem. A feature of the routine is its ability to pass through several simplex vertices at each iteration. The algorithm does not require that the matrix {a;,i } satisfy the Haar condition, nor does it require that it be of full rank. Complete details of the method may be found in [1J. Computational experience with this and other algorithms indicates that it is the most efficient yet devised for solving the /1 problem. The parameters M and N represent the number of equations and number of unknowns respectively. M2 and N2 should be set to M q-2 and N q-2 respectively. The simplex iterations are carried out in the two dimensional array A of size (M2,N2). Initially the coefficients of the matrix {a,. j} should be stored in the first M rows and first N columns of A, and the …

Branchial innervation and ciliary control in the ascidian Corella.

Abstract: The cilia lining the stigmata of the branchial sac of an ascidian circulate water through the animal. These stigmatal cilia are under nervous control; when either siphon is stimulated, both siphons close by muscular contractions and at the same time the stigmatal cilia stop beating simultaneously in all parts of the branchial sac. Spontaneous ciliary arrests may also occur, with or without associated closure of the siphons. Elements of the branchial nervous system that run in the gill bars are assumed to be concerned in coordination of the ciliary arrests. The majority of the branchial nerve fibres emerge dorsally from the visceral nerves that form the posterior brain roots, although nerves are also believed to enter the branchial sac along its anterior margin. No cell bodies could be found in the branchial nerves or in the visceral nerves, so that the cell bodies of the branchial nerve fibres are assumed to lie in the central nervous system. The branchial nerve fibres form a peripheral conducting net extending throughout the branchial sac. Branches of these nerve fibres terminate in contact with some of the ciliated cells; cell-to-cell conduction (through close junctions?) probably spreads excitation to the other ciliated cells. Nerve-nerve junctions appear to be more sensitive to curare than those between nerves and ciliated cells. Electrical recordings from the branchial sac, obtained with suction electrodes, show that arrest of the cilia is accompanied by electrical activity, and that prolonged arrest is maintained by trains of regular pulses. Intracellular microelectrodes in the ciliated cells indicate that these cells have a negative resting potential of 30-40 mV, and that a ciliary arrest is associated with a positive-going spike of 45-50 mV. The externally recorded 'ciliary arrest potentials' probably represent the coordinated depolarization of many ciliated cells. The rhythmical character of the trains of pulses presumably depends on pacemaker activity; this is not localized, since intact organisms or isolated small portions of the branchial sac are capable of generating similar trains of pulses. During the arrest response the stigmatal cilia first perform a reverse beat, then maintain the reverse position for several seconds before slowly relxaing and after several more seconds recommencing to beat with progressively increasing amplitude. The duration of the arrest response varies in media with different concentrations of the common cations, and also varies in response to repetitive stimulation, in a manner which suggests that the depolarization of the ciliated cells is associated with an influx of Ca$^{2+}$, so that the ciliary control here may have some close parallels with that described for Paramecium.

Ocelli of hydromedusae

Abstract: The very simple ocelli of Leuckartiara octona are formed of a sheet of mixed ectodermal receptor and pigment cells, whereas in Bougainvillia the cell sheet is invaginated to form an ocellar cup. The ocellar cup of Tiaropsis is formed of endodermal pigment cells. The receptor cell bodies of Tiaropsis lie outside the cup, their distal processes filling the cup. Each receptor cell process bears a single cilium at its distal end except in Bougainvillia where the number of cilia may vary from one to three. Lateral microvilli are missing from the ciliary membrane of Leuckartiara, poorly developed in Tiaropsis and well developed in Bougainvillia. The proximal part of the receptor cell forms an axon which enters into the subumbrellar nerve ring in Tiaropsis and exumbrellar nerve ring in the other two. The pigment cells lack distal processes in Tiaropsis, in Leuckartiara they bear microvilli and in Bougainvillia they form a strand of 1μ diameter which passes through the ciliary region and then divides into a number of tubules to fill the distal region of the ocellar cup. Bougainvillia medusae showed a swimming “off response” to light of 446–625 nm wavelength but no such response was observed when the ocelli are removed. The evolution of ocelli in hydromeduase is discussed.

Occurrence of Potential Pathogens in Water Containing Ornamental Fishes

Abstract: The bacterial population of the water supplied with ornamental fish purchased from retail outlets was examined qualitatively and quantitatively. As many as 109 viable aerobic organisms per 100 ml were present, with fecal coliform counts as high as 105 per 100 ml. Citrobacter, Escherichia, Pseudomonas, and Vibrio were isolated from 75% or more of the samples, whereas Aeromonas, Alcaligenes, Enterobacter, Flavobacterium, and Streptococcus were isolated from 45 to 65% of the samples. Pseudomonas aeruginosa, Edwardsiella tarda, and Klebsiella pneumoniae were also isolated.

The carnivorous habit of members of the septibranch genus Cuspidaria (Mollusca: Bivalvia)

Abstract: The septibranch bivalves Cuspidaria rostrata and Cuspidaria obesa are carnivores. The food-capturing organ is the inhalant siphon, which can be suddenly protruded towards potential prey such as copepods and ostracods, while simultaneously a strong inhalant current is created. When the septum is rapidly contracted blood is forced from mantle sinuses into the rostral and siphonal sinuses, causing the protrusion of the inhalant siphon. The septal contraction also leaves negative pressure in the infra-septal palliai chamber and produces the inhalant current. The stimulus for the directional food-capturing response is a low-frequently vibration which acts upon mechanoreceptors situated in the siphonal tentacles. Small crustaceans are the most frequent prey. Protein digestion is initiated extracellularly in the stomach.

Singularities in Weyl gravitational fields

Abstract: The peculiarities of the scalarS ≡RijklRijkl are exhibited for two axially-symmetric static (Weyl) gravitational fields. By examiningS along curved families of trajectories to the Weyl singularities, examples are found which contradict previous claims by Gautreau and Anderson regarding ‘directional singularities’. Proper circumferences about the Bach and Weyl line-mass singularity are also examined. There is no apparent correlation between the source structure and the behaviour ofS from this analysis.

Tourism: an exercise in spatial search

Abstract: THERE IS a growing interest in how people learn about the choices or opportunities that exist in their local area, and how they establish regular patterns of movement to utilize these opportunities. Research in this area has centred on consumer market activity, because consumption is, in many ways, a learned response. Formally defined, learning means “all changes in behavior that result from previous behavior in similar situations,”’ so that the consumers’ spatial behaviour can be regarded as an evolving process, based on their experience with current and past locations. It has been postulated that the spatial patterns associated with consumer market activity are the result of a learning process whereby an individual searches his area for the “most satisfactory” pattern of responses.2 Utilizing the reinforcement theory of Hull’s3 “Behavior System,” Golledge and Brown4 suggest that in the early stages of the learning process an individual’s search procedure will be random; but the haphazard nature of the search will diminish as the individual develops more satisfying experiences from the choices or trials he has made. Finally, the consumer will reach a stage of general satisfaction with his choices that is likely to lead to a habitual set of responses and a stable movement pattern within his area. However, the close association with stimulus-response learning theory has meant that geographical research into spatial search has emphasized the trial and error aspect of learning while minimizing its cognitive elemenk5 Cognitive behaviour and experience can intervene in a stimulus-response situation and modify the learning process via the individual’s perception, attitude, motivation (physical and psychological), and inter-trial learning.G Such personal attributes are likely to influence the degree of commitment an individual makes to a search and affect the procedure by which he builds up his mental image of an area. Thus it is important that the contribution of individuality be examined in addition to the more stereotyped behaviour of stimulus-response learning. This paper reports on an investigation of the motivations and modus operandi involved in the spatial search of a new area. The individuals concerned were first-time tourists to Vancouver Island, British Columbia, and the study examined events and expectations associated with their search process. Tourism provides an attractive medium for the study of spatial search because the tourist encounters many new environments during his trip, and these must be assimilated in a short time. Therefore, although he may not advance to the hypothesized habitual state of response and movement during his first visit, the tourist’s search experience could provide insight into which methods and cues have a high ‘Lpay-off” and into the relevance of cognitive variables. Furthermore, the way in which the tourist explores each location is of vital interest to local tourist industries which need to create maximum exposure and use for each tourist attraction during their short season. This study of tourist search behaviour was conducted as part of a broader survey7

Calcium ion transport by pig erythrocyte membrane vesicles.

Abstract: Preincubating pig erythrocyte membranes with ATP enhances their ability to accumulate Ca(2+) against a concentration gradient. The extent of this increase is dependent on preincubation time over the period 0-60min. As the accessibility of outside membrane markers is decreased by preincubation and as accumulated Ca(2+) is not removed by EGTA [ethanedioxybis(ethylamine)tetra-acetate], it is suggested that ATP causes the formation of sealed inside-out vesicles which can transport Ca(2+) inward. The transport system requires ATP and Mg(2+) and exhibits an apparent dissociation constant for Ca(2+) of approx. 100mum. Since the dissociation constant for Ca(2+)-sensitive ATPase (adenosine triphosphatase) in these preparations is similar, it is concluded that this ATPase is responsible for Ca(2+) transport. Polyphosphoinositide concentrations are also increased during incubation with ATP; however, there is no change in their rate of synthesis or breakdown during Ca(2+) transport.

A feng shui model as a location index

Abstract: Oral tradition states that the first Chinese cemetery in Victoria, Canada, was possibly west of Swan Lake, but its precise location and history are unknown. The application of an ideal Feng Shui topographic model and the use of aerial photographs, cadastral and topographic maps, material in Chinese archives, and records of the Land Registry Office, show that the Chinese Association in Victoria purchased a plot of land north of Swan Lake in 1891. The site could not be used as a cemetery because of objection by residents in the vicinity.

Sterility of salmonid roe and practicality of hatching gnotobiotic salmonid fish.

Abstract: The ventral surface of spawning salmonid fish was opened aseptically and the roe were removed aseptically. Roe obtained by using this technique were demonstrated to be sterile. Aseptic fertilization and incubation of eggs obtained in this manner resulted in the hatching of gnotobiotic salmonid fish.

The fading of stabilized images: Eye movements and information processing

Abstract: Two experiments are reported which indicate that neural and photochemical satiation processes are inadequate to explain the fading of the stabilized retinal image. When eye movements are attempted over the stimulus, fading occurs more rapidly, indicating an information processing component in the disappearance of the image.

The floating potential of a Langmuir probe in a high-pressure plasma

Abstract: The floating potential (ie the potential assumed by a probe when the net current collected by it is zero) of a spherical electrostatic (Langmuir) probe in a collision-dominated plasma is investigated. The plasma is considered to be either static or flowing at subsonic velocities. The experimentally realistic situation is also considered where the probe is cold compared with the bulk plasma. The two extreme probe temperature conditions are discussed: that in which the electrons remain at their uncooled temperature, characteristic of the bulk plasma; and that in which they cool to the temperature of the neutrals near the probe. It is concluded that only in the case when the electrons cool and the sheath is thin does the floating potential vary appreciably from its value obtained in the absence of thermal gradients and thermoelectric effects. Experimental results are presented which support the concept that, for the opposite of the above condition (ie uncooled electrons, thick sheath), the floating potential is unaffected. In addition, the data have also been analysed in a manner suggested by Lam to yield an accurate value for the electron temperature.

Holography of the Eye: A Critical Review

Abstract: Holography is a technique producing a three-dimensional picture of a real physical object. A hologram is a recorded interference pattern between light coming from an object (the object field) and light coming from a suitable reference source (the reference field).

Social class in atacama company towns

Abstract: The high degree of control of workers in company towns is reflected in major physical and social features which include a rigid ground plan, architectural uniformity, dominance of the townscape by company institutions, deliberate allocation of social classes to housing of distinct quality types, and strong ethnic and class segregation. Most of these features are the result of company planning policies. Developed in Europe and North America, this model has been transferred to the Atacama desert by United States copper interests.

Meiji Primary School Language and Ethics Textbooks: Old Values for a New Society?

Abstract: George Sansom once called the history of education in late nine-teenth-century Japan ‘a useful example of a reaction against foreign influence and a return to tradition in the midst of a strenuous process of “modernization”.’ Sansom and others have depicted Japanese education during the first three decades of the Meiji period (1868–1912) as follows: during the 1870s Japanese education was completely dominated by the Western philosophies and principles which were flooding a country newly opened to foreign intercourse after two and one-half centuries of isolation. This extreme Westernization led to a ‘conservative reaction’ in government and education circles during the 1880s. This, in turn, culminated in the Imperial Rescript on Education of 1890 and the emphasis on ‘traditional’ moral education which was the hallmark of schooling in the 1890S. This shift in educational policy on the part of the Meiji government has been seen as ‘part of the general swing during the 1880s away from unnecessarily close imitation of the West and back towards more traditional values.’

Evaluation of Aquarium Antibiotic Formulations

Abstract: The antibacterial activity of eight products marketed for the therapy and prophylaxis of diseases of ornamental fishes was tested. The products contained erythromycin, neomycin, a nitrofuran, penicillin, sulfa compounds, streptomycin, or tetracycline. When used at the concentration recommended by the manufacturer, the products failed to inhibit the growth of bacterial species known to be potential pathogens of ornamental fishes and failed to reduce significantly the bacterial numbers in water containing fish. Concentrations of the products that were bacteriostatic were markedly higher than the in-use concentration recommended by the manufacturer. The danger presented by the unrestricted availability of antibiotic compounds frequently used in the treatment of human and animal disease is discussed.

Solution of the Boltzmann equation at the upstream and downstream singular points in a shock wave

Abstract: A solution of the Boltzmann equation is obtained at the upstream and downstream singular points in a shock wave, for the case of Maxwell molecules. The fluid velocity u, rather than the spatial co-ordinate x, is used as the independent variable, and an equation for ∂f/∂u at a singular point is obtained from the Boltzmann equation by taking the appropriate limit. This equation is solved by using the methods of Grad and of Wang Chang & Uhlenbeck; and it is observed that the two methods are the same, since they involve not only an equivalent system of moment equations but also the same closure relations. Because many quantities are zero at a singular point, the problem becomes sufficiently simple to allow the solution to be carried out to any desired order. At the supersonic singular point, the solution converges very slowly for strong shock waves; but a simple modification to Grad's method provides a rapidly convergent solution. The solution shows that the Navier-Stokes relations, or the first-order Chapman-Enskog results, do not apply unless the shock-wave Mach number is unity, and that they are grossly in error for strong shock waves. The solution confirms the existence of temperature overshoot in a strong shock wave; shows that the critical Mach number in Grad's solution increases monotonically with the order of the solution; provides a simple explanation as to why Grad's closure relations fail and shows how they can be improved; and provides exact boundary values that can be used to guide future numerical solutions of the Boltzmann equation for shock-wave structure.

Electromagnetic Response of a Conducting Sphere Buried in a Conducting Earth

Abstract: D'YAXONOV's (1959) general solution for the problem of induction in a conducting sphere embedded in a uniform conducting half-space by a spherically symmetric source has been evaluated numerically for the particular case of an overhead vertical magnetic dipole source. The validity of the numerical results are examined by comparing the results for several cases with analogue model measurements. Numerical results for a range of source frequencies, sphere radii, depths of burial, and conductivity contrasts of geophysical interest are presented.

Some convolution integral equations

Abstract: In the present note the authors consider the convolution integral equation ∫ 0 x (x−t) Q−1 H m,n p,q [x−t]f(t)dt=g(x), where Hp,qm,n[z] denotes the familiar H-function of C. Fox [Trans. Amer. Math. Soc. 98, 395–429 (1961). MR 24 # A 1427], f is an unknown function, and g is prescribed such that g(l)(0)=0, l=0, 1, …, r−1, r being a positive integer. A systematic discussion of the question of solvability of the integral equation (∗) in terms of recognizable functions is presented, and several known or new special cases are indicated.

Dimensional Dominance and Extradimensional Shifts

Abstract: 60 9-yr.-old school children made similarities judgments about stimuli on the basis of form, color and size using a triads method. They then learned a size discrimination which was followed by extradimensional shifts to either form or color. Shifts to the dominant dimension of form were performed faster than shifts to the non-dominant dimension of color. All Ss were form dominant on both pre- and post-training assessment.