Showing papers by "Durham University published in 1972"

A primer of signal detection theory

Abstract: Contents: Foreword. Preface. What Are Statistical Decisions? Non-Parametric Measures of Sensitivity. Gaussian Distributions of Signal and Noise With Equal Variances. Gaussian Distributions of Signal and Noise With Unequal Variances. Conducting a Rating Scale Experiment. Choice Theory Approximations to Signal Detection Theory. Threshold Theory. The Laws of Categorical and Comparative Judgement. Appendices: Answers to Problems. Logarithms. Integration of the Expression for the Logistic Curve. Computer Programmes for Signal Detection Analysis. Tables.

Implanted hearing aids

Abstract: Several hearing aid configurations for implantation within the middle ear cavity are disclosed. Each hearing aid is minute in size and is joined in operative relationship interiorly of the ear drum to the ossicle bone chain situated within the middle ear cavity. Each hearing aid is characterized by: (1) picking up or ''''reading'''' auditory signals off the ear drum, (2) subsequently amplifying and/or transmitting such signals directly to appropriate sound receiving mechanisms, natural or solid-state or both, located on the oval window, the round window, or the promontory leading into the inner ear, and (3) relying upon the automatic gain control (AGC) function performed by the tensors and flexors of the ossicle bone chain to prevent loud sounds from damaging the ear drum.

Stress Systems at Young Continental Margins

Abstract: A study of stresses associated with young continental margins shows that differential loading across major surface features of the Earth may cause tectonic activity within lithospheric plates.

The Young's modulus and Poisson's ratio of arsenic, antimony and bismuth

Abstract: The orientational dependences of the Young's modulus and Poisson's ratio of the A7 structure elements arsenic, antimony, and bismuth are investigated, using available experimental data of the six elastic compliance constants. The behaviour of these technical elastic constants in antimony and bismuth is shown to differ not only in degree but also in kind from that of arsenic, which exhibits the characteristics expected of a layer-like crystal; arsenic is elastically a very anisotropic material, its Young's modulus varies by a factor as large as 11.3: the largest anisotropy ratio reported for a metallic element.

Patterns of daily activity in mammals

Abstract: Summary The adaptation of the various mammals to all gradations between a totally diurnal to a totally nocturnal pattern of activity is noted and the nature of the determinants of the high proportion of species which are crepuscular or nocturnal is discussed. It is seen that detailed study of the activity patterns has been confined to a small proportion of species, principally some of the smaller rodents. Ruminants are unusual in remaining vigilant during normal sleep, loss of awareness of external events being confined to periods of paradoxical sleep which occupy a very small proportion of the 24 hours. The 24 hour rhythm of activity has an endogenous basis. Under normal conditions it is entrained by the changes in light intensity at dusk and dawn, but circadian activity rhythms can be entrained to periodicities longer or shorter than 24 hours. Relatively small variations in the intensity of the lighting between day and night are effective in maintaining entrainment, but under arctic conditions in summer the 24 hour rhythm becomes much less pronounced and activity may even develop a free–running pattern. A short–term rhythm with a regular periodicity of a small number of hours has been reported to occur by many authors in species of small eutherian mammals feeding on a bulky diet, that is insectivores and the more herbivorous of the small rodents. A summary account is given of information, much of it derived from unpublished research, indicating that in fact the patterns of diel activity of such rodents vary greatly with the environmental conditions. The duration of daylight is apparently only one of many factors affecting the distribution of their activity over the 24 hours. It is noted that versatility of this nature also occurs in some large mammals. It is concluded that an advance in knowledge of the mechanisms determining the activity patterns of mammals will require a greater emphasis on field observations of mammal behaviour and on laboratory experiments in which the variety of conditions found in nature is closely simulated.

Biochemistry of protein synthesis in plants

Abstract: 111. Protein synthesis in chloroplasts . . . . 130 A. Introduction . . . . . . 1 3 0 B. Chloroplast autonomy . (I) DNA . (2) DNA polymerase. . (3) RNA polymerase. . (4) Protein synthesizing apparatus (a) Ribosomes . (b) Amino acid activation . (c ) Initiation . (d) Energysource . (e) Inhibitors . . I 3 1 . 132 . 136 . 1 3 6 * I37 . 140 . I41 . 142 . I43 . I43 C. Function of chloroplast ribosomes . . I 4 4 (I) Evidence from studies of inhibitors in wivo . . I 4 4 (2) Products of protein synthesis in oitro . . . . 146 IV. Protein synthesis in mitochondria . . . A. Brief description of the mitochondrion . B. DNA . . . . C. DNAreplication . D. DNA transcription . E. Protein synthesis . .

Lead: levels in roadside invertebrates and small mammals

Abstract: Concentrations of lead in the bodies of roadside invertebrates were generally below 50 p.p.m., but reached nearly 700 p.p.m. in woodlice (Isopoda). Lead levels in tissues of small mammals caught on roadside verges did not exceed 30 p.p.m., and were thus less than the levels found in many of their prey. No evidence was found of decreases in abundance of invertebrates with increasing levels of lead in soil and vegetation close to roads.

The genetic significance of almandine-pyrope phenocrysts in the calc-alkaline Borrowdale Volcanic Group, Northern England

Abstract: A suite of garnet-bearing andesites and dacites from the Ordovician of N. W. England is described and major- and trace-element analyses of the garnet phenocrysts are presented. The garnets are of almandine-pyrope composition, with minor amounts of spessartine and grossular, and often show marked reversed zoning; the crystal becoming progressively enriched in pyrope towards the margin. Garnets from the dacites are consistently richer in almandine and spessartine than are those from the andesites.

A phylogeny of higher plants based on the amino acid sequences of cytochrome c and its biological implications

Abstract: Higher plant phylogenetic trees were constructed from the amino acid sequences of cytochrome c from fifteen plants using the ‘ancestral sequence’ and ‘flexible numerical’ methods. The validity of these methods is discussed and the results obtained are compared with existing phylogenies based mainly on morphological characters.

The theory of charge exchange

Abstract: This report describes the development of the theory of charge exchange in collisions of ions with atoms or ions, paying particular attention to the work of the last decade. The successful approximations based on the impact parameter and classical path methods, suitable for low energy collisions, are treated in detail. For high energies, approximations that are completely satisfactory from a theoretical viewpoint do not exist, but both the Born approximation and the classical models of Gryzinski and Thomas are found empirically to reproduce many features of the observed cross sections and a discussion is given of the successes and limitations of these and related models. This review was completed in March 1972.

The time of origin of the flowering plants determined by using amino acid sequence data of cytochrome c

Abstract: Summary Cytochrome c sequences from nineteen plants have been used, in conjunction with those of animal and fungal origin already published, to calculate the times of origin of the animal, fungal and plant kingdoms and also of some higher plant groups. The results show that the Angio-sperms originated at least several geological periods before the Cretaceous, which is the earliest period in the geological record in which authentic angiosperm fossils have been found.

Selecting Creativity Tests for Use in Research.

Abstract: This study looks at the problem of creativity tost selection by examining the relationships between 15 divergent and non-divergent tests. This practical problem raises two main theoretical issues: whether ‘creativity’ is a unitary dimension across and within tests, and what relationship this range of abilities bears to IQ. A secondary aim is to evaluate four new tests by comparison with the 11 others. The tests were administered, along with two IQ reference measures, to 117 10- to 11-year-old school children. Factor analysis of the resulting intercorrelations led to the conclusion that ‘creativity’ implies an integrated range of abilities represented by the divergent tests which, although related to general intelligence in subjects of average IQ, remains factorially distinct from it; within tests, Fluency, Flexibility, Originality and Elaboration subscores were highly intercorrelated. Thus, providing that all modes of response and types of test material are included (drawing/writing; verbal/non-verbal content), the actual divergent tests chosen are not of vital importance, and calculation of anything other than Fluency scores adds little information. Analysis of the four new tests confirmed this conclusion, and led to suggestions for their further development.

Forgetting as a function of sleep at different times of day

Abstract: The experiment studied the separate effects of sleep and time period of retention interval on forgetting. A free recall task was given to independent groups of subjects either at night or in the morning, and a second recall demanded 5 h later, after an intervening period of sleeping or waking activity. Oral body temperatures (BT) were measured at each session. The data were analysed in terms of (a) immediate recall at test 1, and (b) amount forgotten from test 1 to test 2. Immediate recall was higher for morning groups, in agreement with previous findings, serial position analysis indicating that the effect is confined to enhancement of the primary memory component. Long-term retention was higher over the night interval, irrespective of sleeping conditions, though having slept at night produced better retention than having stayed awake. Sleep during the morning was not effective in reducing forgetting. BT showed a marked drop for both night groups and rise for day groups over the retention interval. Alter...

Contrast and size variables and the tilt after-effect.

Abstract: The relationship between the contrast and bar width of adapting and test gratings in the determination of the magnitude of the tilt after-effect was explored. When the contrast of adapting and test gratings is varied concomitantly over four levels, the magnitude of the tilt after-effect does not change. When the contrast of the adapting grating is higher than the test grating, the magnitude of the after-effect is increased and when its contrast is lower than the test grating, the magnitude of the after-effect is decreased. When the bar width of the test grating is narrower or broader than that of the adapting grating, the magnitude of the after-effect does not change. The implications of these results for a neurophysiological explanation of the tilt after-effect are discussed.

Process and Product in Children's Drawing:

Abstract: Aesthetic and expressive theorists have tried to understand what children's drawings represent. It is, however, a prior necessity to investigate the perceptual–cognitive mechanisms which permit the development of representational drawing, and to specify the role played by developing graphic and cognitive skills. In the first place it is argued that the concept of interpretation, as carried out by the child himself as well as by adults, rests on a dual basis consisting of perceptual processes and the recognition of conventions. Secondly some empirical examples of the problems of organisation with which the child has to deal are given. Through a critique of the model and the developmental taxonomy worked out by Luquet, the elements of a general model, embodying the concepts of interpretation and organisation, are put forward.

Ultrasonic Study of Lattice Stability in Indium + Thallium Alloys

Abstract: Ultrasonic wave velocities and attenuation have been measured by the pulse echo method in both the cubic and tetragonal forms of indium + thallium alloys in the vicinity of the martensitic phase transformation. Results lead to insight into the lattice stability of the alloys and the microscopic nature of the transition; anomalously small values of the modulus ½( C 11 – C 12 ) found in both crystallographic modifications, coupled with marked increases in ultrasound absorption near the transition, attest to lattice mode softening as the basis of the transformation mechanism. Detailed measurements of the components of the stiffness tensor of a 10 at. % thallium alloy are presented and compared with those of indium itself. The lower crystal stability of the alloy relative to that of indium is graphically demonstrated by sections of velocity surfaces. A sensitive indication of the impending phase change is found in the linear compressibilities: indium and its tetragonal alloys with thallium show a marked inclination to adopt a cubic structure.

The characterisation of vicilin during seed development in Vicia faba (L.).

Abstract: Vicilin and legumin were extracted from developing seeds at different stages using the classical method of repeated isoelectric precipitations. The subunits of these two protein fractions were separated by SDS gel electrophoresis, and it was shown that the sub-unit structure of vicilin changed during development whereas that of legumin did not. Thus vicilin is not a single protein.