Showing papers by "University of Alberta published in 1970"

Enhancement of Teleseismic Body Phases with a Polarization Filter

Abstract: Summary A time domain polarization filter, originally proposed by Flinn, has been modified and is used to increase the signal to noise ratio of teleseismic body phases. Both the rectilinearity and direction of particle motion is obtained from the co-variance matrix for three components of ground motion over a small time interval. The estimate of rectilinearity is found by diagonalizing the matrix and forming a function that involves the ratio of the largest and intermediate principle axes of the matrix. The direction of polarization is found from the eigenvector of the largest principle axis. A set of time-varying operators are then obtained which act as a point by point gain control to modulate the digital seismic records. This non-linear filter is useful for enhancing P, pP, sP, PP, S and other compressional or shear phases. When applied to an array of three-component stations it appears to be possible to identify multiple events in the source function of some earthquakes. 1. Iotroductioo As any seismograph record is always noise contaminated, the detection and interpretation of seismic events requires knowledge of the characteristics of both signal and noise. Elastic body waves, which may be generally separated into P (compressional) and S (shear) phases, can be considered as non-dispersive group arrivals with maximum power in the 0.3 to 10-second period range. Surface Rayleigh and Love waves may be described as dispersive group arrivals with maximum power in the 2-to 100-s period range for earthquakes of moderate magnitude, the observable periods extending up to 57 min for larger teleseismic events. Superimposed on these signals is microseismic background noise as well as signal generated noise. Signal generated noise is the result of multiple reflections and refractions of P and S body waves at crustal interfaces and inhomogeneities and local conversion of body waves to surface waves; this type of noise originates primarily under the recording station. Microseismic noise, which is considered to consist mainly of fundamental and higher mode Rayleigh waves, has been shown to exhibit a sharp peak in the 540 8-s period range (Brune & Oliver 1959). As a result of this sharp peak in the microseismic noise spectrum, frequency bandpass filtering is often employed to improve the signal to noise ratio. Although this type of filtering is very effective in removing microseismic background from both long and short period data, it often cannot distinguish between signal and signal generated noise. Difficulty may still arise in the attempted identification of phases whose frequency characteristics are similar.

Ion–Molecule Reactions in Pure Nitrogen and Nitrogen Containing Traces of Water at Total Pressures 0.5–4 torr. Kinetics of Clustering Reactions Forming H+(H2O)n

Abstract: The ion–molecule reactions in pure nitrogen and nitrogen containing traces of water were studied with a pulsed electron‐beam mass spectrometer having a field‐free high‐pressure source. The reaction N2++2N2 = N4++N2 occurring in pure nitrogen was found to have a third‐order rate constant k = 8 × 10−29cc2molecule−2·sec−1 at 300°K and a negative temperature coefficient corresponding to an “activation energy” of − 2 kcal/mole at pressures up to 3.5 torr. The results for the reaction N++N2→N3+, investigated under the same conditions, indicated either third‐order dependence with k = 5 × 10−29cc2molecule−2·sec−1 and energy of activation − 1 kcal/mole or second‐order dependence with k = 1.3 × 10−12cc molecule−1·sec−1 with no temperature coefficient. The reaction mechanism in nitrogen in the torricelli range containing water vapor in the millitorr range was found to proceed by the following reaction sequence: N2+→N4+→H2O+→H3O+→H+(H2O)2→H+(H2O)n. The rate constants for all reactions were determined. The clustering ...

Event horizons in static scalar-vacuum space-times

Abstract: The following theorem is established Every zero-mass scalar field which is gravitationally coupled, static and asymptotically flat, becomes singular at a simply-connected event horizon In the special case where the gravitational coupling of the scalar energy density is neglected, the solutions are computed explicitly Some properties of the singular event horizons are discussed, and a brief mention of related work with non-static scalar fields is given

Discharge patterns of coxal levator and depressor motoneurones of the cockroach, periplaneta americana

Abstract: 1. Observation of movements of the metathoracic legs of the cockroach before and after section of peripheral nerves allowed identification of muscles involved in flexion and extension of the femur. 2. Extracellular recordings from the nerves to these coxal muscles show that during rhythmic leg movements bursts of activity in a number of levator motor axons were strongly reciprocal and generally non-overlapping with those of a slow depressor motor axon. 3. These reciprocal patterns persisted after removal of all sensory input from the legs. 4. The durations of levator bursts were relatively constant compared to those of the depressor, corresponding to the behavioural observations on leg protraction time. The pattern was asymmetric: levator bursts could be generated without depressor activity, but never the reverse. 5. No evidence was found for inhibitory collateral pathways between antagonist motoneurones. 6. It is proposed that levator motoneurones are driven by a group of bursting interneurones which simultaneously inhibit the ongoing depressor activity.

Source of the kerr metric

Abstract: Assuming that the Kerr-Newman metric is the field of a layer of mass and charge distributed over the equatorial disk spanning the ring singularity, the source distribution on the disk is computed explicitly. In the uncharged case, this interpretation automatically excises the noncausal parts of the manifold, so that one obtains the unique source of the causally maximal extension of the vacuum metric. A Newtonian field which gives the same source distribution is exhibited, and shown to be closely analogous to the relativistic case. In particular, the Newtonian particle orbits show the same avoidance of the ring singularity that is such a remarkable feature of geodesics in the Kerr geometry. In the charged case, we examine how the gyromagnetic moment (which is equal to that of the Dirac electron) is reflected in the character of the source distribution.

Virtual orbitals in hartree--fock theory.

Abstract: An arbitrariness of virtual orbitals in the Hartree-Fock theory is discussed, and it is explicitly demonstrated that the energy spectrum of the virtual orbitals can be manipulated so that the convergence property may be improved in the perturbation theory and the configuration interaction calculation based on the Hartree-Fock equation

Mechanism and Rate Constants of Ion–Molecule Reactions Leading to Formation of H+(H2O)n in Moist Oxygen and Air

Abstract: The formation of H+(H2O)n clusters in moist oxygen is of interest since this process must occur in the troposphere and has been observed to occur in the D region of the ionosphere. The reaction mechanism leading from O2+ to H+(H2O)n was investigated with a pulsed electron‐beam high‐pressure mass spectrometer. At oxygen pressures in the torr range and for [O2]/[H2O]>102 the major reaction proceeds by the sequence O2+→O4+→O2+·H2O→H3O+·OH→H+(H2O)2→H+(H2O)n. The rate constants for all major steps were determined. Rate constants for parallel reactions which may become important at different conditions were also determined.

The influence of artificial cranial deformation on discontinuous morphological traits

Abstract: Following the elucidation by geneticists of the nature of minor skeletal variants in the mouse, anthropologists have stressed the potential of these traits for tracing the affinities and movements of extinct human populations. Earlier Sullivan observed that discrete traits could be particularly valuable where artificial cranial deformation limits the use of craniometry. Twenty-eight minor variants were studied in bifronto-occipitally deformed and undeformed skulls of a sample of 78 from a single Hopewell mound. The pattern of frequency differences between deformed and undeformed with respect to traits at the back of the vault and in the frontal region, interpreted in developmental terms, reveals a hypostotic effect in these regions in the deformed skull; while, in contrast, traits of the lateral vault, facial skeleton and cranial base point to a general hyperostotic effect in these regions. Each of three emissaria tends to be more constant in the deformed. That minor cranial variants manifest a plastic response to this type of environmentally-imposed stress is consistent with the nature of such variants as elucidated by genetics research in mice. The findings suggest that deformed crania should be excluded from population studies in which genetic divergence between groups is estimated in terms of cranial trait frequencies.

On the Relationship between My Avatar and Myself

Abstract: What is the relationship between avatars and the people they represent in terms of appearance and behavior? In this paper, we hypothesize that people (balancing motives of self-verification and self-enhancement) customize the image of their avatars to bear similarity to their real selves, but with moderate enhancements. We also hypothesize that virtual-world behavior (due to deindividuation in computer-mediated communication environments) is less restrained by normal inhibitions than real-world behavior. Lastly, we hypothesize that people with more attractive avatars than their real selves will be somewhat more confident and extraverted in virtual worlds than they are in the real world. We examine these issues using data collected from Second Life residents using an in-world intercept method that involved recruiting respondents’ avatars from a representative sample of locations. Our quantitative data indicate that, on average, people report making their avatars similar to themselves, but somewhat more attractive. And, compared to real-world behavior, respondents indicate that their virtual-world behavior is more outgoing and risk-taking and less thoughtful/more superficial. Finally, people with avatars more attractive than their real selves state that they are more outgoing, extraverted, risk-taking, and loud than their real selves (particularly if they reported being relatively low on these traits in the real world). Qualitative data from open-ended questions corroborate our hypotheses.

Lumped-circuit models for nonlinear inductors exhibiting hysteresis loops

Abstract: A new mathematical model of dynamic hysteresis loops is presented. The model is completely specified by two strictly monotonically increasing functions: a restoring function f(.) and a dissipation function g(.). Simple procedures are given for constructing these two functions so that the resulting model will simulate a given hysteresis loop exactly. The model is shown to exhibit many important hysteretic properties commonly observed in practice such as the presence of minor loops and an increase in area of the loop with frequency. In the case of an iron-core inductor, the mathematical model is shown to be equivalent to a lumped-circuit model, consisting of a nonlinear inductor in parallel with a nonlinear resistor. Extensive experimental investigations using different types of cores show remarkable agreement between results predicted by the model with those actually measured. The most serious limitation of this dynamic model is its inability to predict dc behaviors. For the class of switching circuits where dc solutions are important, a special dc lumped-circuit model is also presented.

Load-induced Earthquakes at Lake Kariba–II

Abstract: Summary The filling of the world's largest artificial lake at Kariba has been accompanied and followed by considerable earthquake activity. A local network of three seismographs allowed location of epicentres for 159 of 2000 tremors recorded during three years while the lake filled. The epicentres lie in the down-faulted rift valley of the middle Zambezi and it is clear that the lake has re-activated some of the existing faults, formed in a complex tectonic history since late Precambrian times. Records from permanent observatories have been used in estimates of tremor frequency and rate of energy release through 9.4 years. Calculations of stress distributions at nine lake levels have been used in estimates of the volume V, within which the maximum shear stress exceeds 1 bar, and V, as function of time is compared with the seismic activity. The latter was highly correlated with rise of V, as the lake filled and for three years after. Of total energy 2.32 x lOZ0erg some 88.4 per cent was radiated from seven events of 5.0 < m < 5-8. The main activity built up from June to September 1963, culminating in the last week of September, five weeks after the lake reached its maximum level; during that week five of the seven large shocks and many hundreds of aftershocks occurred. Activity has continued to the present, correlated with water level and more strikingly with V, until mid-1966 but not thereafter, and showing a gradual though far from continuous decline. Magnitude-frequency dependence suggests that all the tremors have been ' aftershocks ' in the sense that they have occurred in prefractured rock of low strength. Energy transformations are considered making use of calculated elastic depressions. It is shown that a vast amount of energy (5.5 x loz4 erg) is stored as elastic strain energy in the lithosphere as a result of release of gravitational energy during depression of the rock in a limited volume, and that the radiated seismic energy can be provided at plausibly low efficiency. Three modes of failure are considered to have been present. In one brief burst of about 200 tremors near the west end of the lake it is believed that the lake triggered failure of a pre-stressed, previously active fault through increment to the stress, to fluid pressure or to both. In another burst of about 50 tremors 15 to 65 km downstream from the dam only triggering of pre-stressed faults by incremental stress is believed probable. In the main activity near and under the deep Sanyati Basin, which included all the large shocks, it is argued, mainly from the correlation in time between activity and growth of V,, that the shear stress of 1 or 2 bars due to the load has triggered failure of faults initially stressed at several tens of bars. Increase of fluid pressure appears to have been

A Typology of Virtual Worlds: Historical Overview and Future Directions

Abstract: Virtual worlds constitute a growing space for collaborative play, learning, work, and e-commerce. To promote study of this emerging realm of activity, we suggest a typology adapted from C. Porter’s (2004) typology of virtual communities. The five elements of the proposed typology include (1) purpose (content of interaction), (2) place (location of interaction), (3) platform (design of interaction), (4) population (participants in the interaction), and (5) profit model (return on interaction). We argue that this five-element typology facilitates identification of (a) the historic antecedents of virtual worlds in gaming and social networking, (b) future applications of virtual worlds for society, education, and business; and (c) topics for future research.

Geomagnetic Deep Sounding and Upper Mantle Structure in the Western United States

Abstract: Summary Magnetic field time variations were observed in September 1967, with a two-dimensional array of 42 three-component variometers between latitudes 36" and 43" N and longitudes 101" W and 116" W. Fourier analysis of a polar substorm and of a storm shows that the former has a smooth spectrum and the latter a complex spectrum with many maxima. Upper mantle conductivity structure can be seen qualitatively in the original variograms, but is far more sharply defined in maps of Fourier spectral component amplitudes and phases. A ridge of high conductivity runs at a depth no greater than 200 km under the Southern Rocky Mountains between the Great Plains and the Colorado Plateau, which marks a low-conductivity region within the Cordillera. A strong conductivity anomaly runs north-south along the Wasatch Front through central Utah, and indicates the presence of an upwelling of highly conductive material at depth no greater than 120 km along the edge of a step structure which brings the conductive mantle to shallower depth under the Basin and Range Province than under the Colorado Plateau. Long-period maps from the storm suggest a rise in the conductive mantle between the northsouth structures, from the Colorado Plateau southward to the Basin and Range. The daily variation shows the conductivity structures and indicates their great extent in depth. The geomagnetic deep sounding anomalies are found to be in excellent agreement with existing heat flow data, and this supports correlation of electrical conductivity with temperature. There is also good correlation with the available seismic velocity information for the upper mantle. 1. Introdaction Geophysical observations of several kinds indicate that the upper mantle of the Earth under North America is laterally inhomogeneous. Upper mantle seismic velocities of 8.0 km s-' or larger are characteristic of the eastern United States and the Great Plains Province, while velocities decrease to values of 7.9 km s-' or lower west of the Rocky Mountains (Herrin & Taggart 1962). A similar pattern is shown by travel-time anomalies of seismic waves at vertical incidence. P and S waves arrive early at stations in the eastern United States; late arrivals are predominant in the western United States (Cleary & Hales 1966; Doyle & Hales 1967; Hemn & Taggart 1968). As the differences between the P travel-time residuals and the gravity anomalies in the central and western U.S. cannot be explained by the Birch (1961) relation between velocity and density, Hales & Doyle (1967) suggested that tempera

The high-alpine vegetation of Central Otago, New Zealand

Abstract: Summary Extensive areas of dwarfed, tundra-like vegetation, mostly beyond the upper limit of the low-alpine snow tussock grassland, are described from 10 mountain ranges in Central Otago. Environmental data from one representative range indicate that, despite a moderate latitude and altitude, summer temperatures, wind, and snow cover in this vegetation zone are comparable in severity with most high-alpine areas overseas. Four major habitat-physiognomic types are recognised: fellfield, herbfield, cushion, and snowbank. They differ both in physiognomy and flora, while their habitats are differentiated by lithology, altitude, exposure and/or duration of snow cover. Fellfield, being essentially lithologically controlled, is the most distinct type and dominates those ranges with either greywacke or weakly or non-foliated schists, as these tend to fracture into angular blocks. Partially active large stone nets may be present. On the remaining ranges, all with strongly foliated schist, fellfield occurs locally a...

A Flexible Neural Analog Using Integrated Circuits

Abstract: An electronic neural analog is described which contains variable absolute and relative refractory periods, two time constants, and separate control of the ``accommodation'' to sub-threshold voltage changes and the ``adaptation'' produced by the occurrence of output pulses (spikes). The extensive use of integrated-circuit operational amplifiers permits an accurate description of input-output relationships over a wide range of values for all parameters. This facilitates comparison of the results obtained both with neural data and mathematical or digitally simulated models of neural activity. The effect of white noise on interval histograms and their parameters is described and its effect when added to other inputs. Noise disrupts the phase-locked patterns produced by sinusoidal stimuli and the averaged response may become a smooth sinusoidal function in the presence of added noise. Adaptation may produce a phase lead to sinusoidal stimuli, while accommodation may produce a phase lag. Corresponding overshoots or undershoots are seen with square-wave inputs.

Cutting down random trees

Abstract: Let T n denote a tree with n (≧ 2) labelled points: we assume T n is rooted at a given point x, say the point labelled 1 (see [3] for definitions not given here). If we remove some edge e of T n , then T n falls into two subtrees one of which, say T k , contains the root x. If k ≧ 2 we can remove some edge of T k and obtain an even smaller subtree of T n that contains x . If we repeat this process we will eventually obtain the subtree consisting of x itself. Let λ = λ( T n ) denote the number of edges removed from T n before the root x is isolated. Our main object here is to determine the expected value μ( n ) and variance σ 2 ( n ) of λ( T n ) under the assumptions (1) T n is chosen at random from the set of n n−2 trees with n labelled points that are rooted at point x , and (2) at each stage the edge removed is chosen at random from the edges of the remaining subree containing x . It follows from our results that μ( n ) ~ (½π n )½ and (2−½π) n ~ (2−½π) n as n tends to infinity. We also consider the corresponding problem for forests of rooted trees and for trees in which the degree of the root is specified. We are indebted to Professor Alistair Lachlan for suggesting the original problem to us.

Properties of action potentials from insect motor nerve fibres.

Abstract: 1. The properties of nerve action potentials in small insect motor nerves were studied using extracellular recording electrodes. 2. A length of nerve was lifted out of solution and recordings were made with respect to the solution either from an intact nerve (triphasic recording) or from near a cut end of the nerve (monophasic recording). 3. In a cockroach nerve, the number of spontaneously active fibres was small enough that corresponding nerve fibres could be identified in each preparation by their action potential amplitude and their pattern of activity. Under controlled conditions, the absolute amplitudes of either monophasic or triphasic records were reproducible and could be used to calculate fibre diameter. The calculations were confirmed from histological sections of the nerve. 4. Conduction velocity varied approximately as the 0.78 power of fibre diameter in a cockroach nerve and as 0.7 power of fibre diameter in a locust nerve. These values are considerably larger than the square root relation predicted if membrane properties are independent of fibre diameter. 5. Membrane properties probably vary with fibre diameter since the action potential duration increases dramatically for fibres below 5 µ in diameter. 6. For the cockroach nerve systematic structural differences between fibres of different sizes are also seen with the electron microscope and the relation of these to the functional differences is considered.

Stress and Deflection in the Lithosphere near Lake Kariba—I

Abstract: Summary Calculations of incremental stress and deflection in the crust have been made as part of a study of load-induced seismic activity at Lake Kariba. A general method is described for computing any desired stress components anywhere in an elastic half-space near a load of any shape on its surface. The program also computes the elastic depression and the gravitational energy converted to stored elastic strain energy. The static incremental stress and depression in the lithosphere near Lake Kariba are discussed with the aid of vertical sections and maps. The maximum shear stress under the deepest part of the lake rises to 2.12 bars, and the downward normal stress to 6.68 bars. The maximum depression in the Sanyati Basin is 23.5 cm. Computed depression differences along the Makuti-Kariba road are shown to be in excellent agreement with results of repeated precise levelling. The deflection is therefore mainly elastic and Young's modulus is near 0.85 megabars for the lithosphere in the area. Some evidence is available which suggests vertical movements of blocks on fault planes, no doubt associated with the earthquakes. Extended relevelling should give results of great scientific and engineering value. Stress differences produced by the lake in the upper mantle are too small to produce flow there, so that inelastic depression of the crust toward isostatic compensation of the load is not to be expected.

Separation of Magnetic Variation Fields and Conductive Structures in the Western United States

Abstract: Summary The variation field of a polar substorm was recorded by an array of 42 variometers in the western United States. This field has been separated by surface integral methods into parts of external and internal origins, at four times in the time domain and at four periods in the period domain. It is shown that the anomalies in the vertical and east-west horizontal variation fields are of internal origin and that the external fields vary smoothly over the array. The separated fields in both domains show internal currents induced in north-south striking conductive structures by the east-west horizontal field. Phase differences between the normal and anomalous fields are about 30°, and indicate large, highly-conducting structures in which self-induction controls the currents. The in-phase normalized anomalous fields at period 89 minutes have been approximated by two-dimensional models made up of upheavals of semi-circular section and a step in the surface of a perfectly-conducting half-space. A semicircular upheaval of radius 150 km from an unperturbed level at depth 360 km models the anomaly related to the Southern Rockies. A step of height 120km at the Wasatch Front, together with a semi-cylinder of radius 100 km under the Wasatch fault belt, give a good approximation to the observed anomaly at the Wasatch Front. The actual structures may be somewhat shallower and smoother. The real conductivity is estimated at 2.10−12 e.m.u., a value which would be expected at temperatures near 1500°C. Such temperatures are reasonable at the depths concerned.

Characteristics of electrogenic sodium pumping in rat myometrium.

Abstract: Sodium-rich myometrium, obtained from the uteri of pregnant rats, rapidly hyperpolarized when 4.6–120 mM potassium was added to the bathing medium at 37°C. Hyperpolarization was due to sodium pumping since the process was markedly temperature dependent, was abolished by ouabain, and required both intracellular sodium and extracellular potassium. The observed membrane potential exceeded the calculated potassium equilibrium potential during hyperpolarization providing evidence that sodium pumping was electrogenic. Hyperpolarization was reduced in the presence of chloride. The rate of sodium pumping may influence potassium permeability since potassium apparently did not short-circuit the pump during hyperpolarization.

Electrical resistivity and deviations from matthiessen's rule in dilute alloys of aluminum, cadmium, silver, and magnesium.

Abstract: Absolute values of the electrical resistivity of polycrystalline silver, aluminum, cadmium, and magnesium and over 20 dilute binary alloys of these metals with different solute concentrations have been measured from 1.5 to 300 \ifmmode^\circ\else\textdegree\fi{}K. From the resistivity data, deviations $\ensuremath{\Delta}$ from Matthiessen's rule have been evaluated for the alloys. Deviations with positive as well as negative sign have been observed at temperatures above 50 \ifmmode^\circ\else\textdegree\fi{}K. These deviations, for all except the hcp alloys of cadmium containing magnesium as a solute ($\mathrm{Cd}\ensuremath{-}\mathrm{M}\mathrm{g}$ alloys), can be explained in terms of a two-band contribution, which can only be positive, and an interference term between the scattering of electrons by lattice vibrations of the host atoms and the excess potential due to the vibrating impurities, which can have either sign. The deviations for $\mathrm{Ag}\ensuremath{-}\mathrm{C}\mathrm{d}$, $\mathrm{Ag}\ensuremath{-}\mathrm{M}\mathrm{g}$, $\mathrm{Ag}\ensuremath{-}\mathrm{A}\mathrm{l}$, and $\mathrm{Al}\ensuremath{-}\mathrm{M}\mathrm{g}$ alloys increase linearly with temperature and those for $\mathrm{Al}\ensuremath{-}\mathrm{A}\mathrm{g}$, $\mathrm{Cd}\ensuremath{-}\mathrm{A}\mathrm{g}$, and $\mathrm{Mg}\ensuremath{-}\mathrm{A}\mathrm{l}$ decrease linearly with temperature in this range. Combined with published data for $\mathrm{Mg}\ensuremath{-}\mathrm{A}\mathrm{g}$ alloys, these results are in excellent qualitative agreement with the predictions of Bhatia and Gupta, who showed that the interference term should be important at high temperatures and should change sign when the ions on the host and impurity sites are interchanged. This agreement is further strengthened by comparison of the slope $\frac{d\ensuremath{\Delta}}{\mathrm{dT}}$ of the experimental results for the alloys of magnesium and aluminum with a semiquantitative calculation by Gupta. Near 250 \ifmmode^\circ\else\textdegree\fi{}K $\ensuremath{\Delta}$ is negative and $\frac{d\ensuremath{\Delta}}{\mathrm{dT}}$ is temperature dependent for $\mathrm{Cd}\ensuremath{-}\mathrm{M}\mathrm{g}$ alloys, and further work is required to clarify this result. Below about 50 \ifmmode^\circ\else\textdegree\fi{}K deviations for all alloys are positive, and the various contributions are discussed. The precise resistivity results obtained over a wide temperature range extend our knowledge of deviations from Matthiessen's rule, but the complexity of the scattering processes makes a detailed comparison with theory difficult, particularly at low temperatures.

Vocalizations Elicited By Electrical Brain Stimulation in Coturnix Coturnix Japonica

Abstract: 1. Most of the natural calls emitted by adult Japanese quail in the breeding phase of their life cycle could be placed into 15 categories. Brain-stimulation elicited vocalizations resembled examples of 10 of the 15 call categories.

Primary structure of alpha-lytic protease: a bacterial homologue of the pancreatic serine proteases.

Abstract: : Comparison of the amino-acid sequence of the bacterial alpha-lytic protease wit the mammalian pancreatic proteases shows homologies in the regions of the N-terminus, the single histidine, an aspartic acid residue, the active serine, and in the positions of the three disulphide bridges. The partial sequence of a trypsin-like enzyme from Streptomyces griseus provides further evidence for divergent evolution of this class of enzymes from a common ancestral gene. (Author)

Faculty patterns in study behaviour

Abstract: A 72 item Study Behaviour Questionnaire (SBQ) was constructed and administered to 314 prospective teachers, enrolled in the Faculties of Arts and Science, before they had started university lectures and again just prior to the first year examinations. The items on the first administration were factor analyzed and 6 factors were obtained: a study organization factor, a motivational factor, and several cognitive style-type factors. The latter appeared to involve two main classes of study strategy: “simplifying” strategies, and “opening-out” strategies. The study organization factor was uncorrelated with performance, but there were consistent correlations, in the Arts faculty only, between the remaining factors and performance. It was suggested that the general tasks demanded of Arts and Science students were different, and required different strategic approaches.