Showing papers by "Keele University published in 1968"
210 citations
TL;DR: Evidence was found that the generators of the two types of response had different spatial distributions or orientations in the brain, and the amplitude of the high frequency evoked responses increased as stimulus frequency was increased near and beyond the point of fusion of perceived flicker.
106 citations
78 citations
TL;DR: Steady-state scalp potentials were evoked by stimulating the eye with monochromatic light whose intensity was sinusoidally modulated at frequencies between 4 c/s and 33 c/S, and the characteristics of the responses suggested that different mechanisms are important near the α frequency and around 16c/s.
59 citations
TL;DR: The effects of changes in the velocity of patterned stimuli are investigated and what seem to be analogous evoked responses to acceleration of the retinal image are found.
Abstract: CHANGES in the brightness and the spatial or temporal pattern of visual stimuli evoke small correlated changes in the electroencephalogram (EEG) potentials recorded from the occipital scalp and can be revealed by averaging the responses to repeated stimuli1–5. We have investigated the effects of changes in the velocity of patterned stimuli and have found what seem to be analogous evoked responses to acceleration of the retinal image.
54 citations
TL;DR: In this article, the optical constants of gold have been determined for photon energies 0.5 to 6.0 eV by internal reflection from annealed gold films on silica glass prisms.
45 citations
TL;DR: In this paper, the fracture energy of float and Pyrex glass plates has been determined in various media using a simple double-cantilever cleavage technique, and the results are discussed in terms of Marsh's hypothesis that localized plastic flow occurs at the crack tip.
Abstract: The fracture energy of Float and Pyrex glass plates has been determined in various media using a simple double-cantilever cleavage technique. Although slow growth of the crack at constant displacement of the cantilever arms was observed in all environments, consistent values for the energy expended when the crack propagates rapidly were obtained. This ‘instantaneous fracture energy’ranged from ∼5000 erg/cm2 (Float glass) or 6000 erg/cm2 (Pyrex) in vacuum to 2500 erg/cm2 (for both glasses) in water. The results are discussed in terms of Marsh's hypothesis that localized plastic flow occurs at the crack tip.
45 citations
TL;DR: More detailed measurements of line-width and g-value variations observed in both the acid-met and azide derivatives of type A myoglobin crystals are summarized and discussed.
Abstract: Details of the way in which haem plane orientations were deduced from g-value measurements on five different crystal types of acid-met myoglobin were given in parts I and II (Bennett, Gibson & Ingram 1957, and Bennett et al. 1961). This paper now summarizes more detailed measurements of line-width and g-value variations observed in both the acid-met and azide derivatives of type A myoglobin crystals. Since these crystals are those for which a detailed X-ray analysis is now available, a direct comparison of this with the electron resonance measurements can now be made. The g-values obtained for the azide derivative are first analysed, and their anisotropy and asymmetry are related to the possible orientation of the azide group itself. The line widths of the electron resonance absorptions, and their angular variations are then summarized and discussed. It is shown that their large magnitudes and rapid variation with angle can be explained in terms of a slight random misorientation of the molecular axes within the crystal, and that, due to the large g-value anisotropy in the acid-met derivative, a standard deviation of only 1.6 degrees in angular distribution is sufficient to explain the results obtained. A similar analysis is also applied to the results on the azide derivative.
42 citations
39 citations
TL;DR: In the two experiments reported here, perceptual suppression of one stimulus by another in such stable situations has been found to be clearly accompanied by correlated changes in the averaged EPs.
Abstract: IT is well known that averaged visually evoked potentials (EPs) from the human occipital scalp show correlations with a number of subjective features of perception; but recent attempts to find EP correlates of the phenomenon of image suppression, as in interocular rivalry, seem to have yielded conflicting results1–4. In most of these experiments contrasting stimuli to the two eyes were allowed to set up spontaneously fluctuating rivalry, and the subject was required to press a key to indicate which stimulus was dominant at any time. There are, however, situations in which the perceptual dominance of one stimulus over another is stable. In the two experiments reported here, perceptual suppression of one stimulus by another in such stable situations has been found to be clearly accompanied by correlated changes in the averaged EPs.
38 citations
TL;DR: In this article, some of the main features of the initiation and propagation of fracture in glass are described and the common flaws which limit the strength of ordinary samples of glass are illustrated.
Abstract: Some of the main features of the initiation and propagation of fracture in glass are described. The common flaws which limit the strength of ordinary samples of glass are illustrated. The characteristic structure of tensile fracture surfaces and some properties of the moving crack are discussed.
TL;DR: In this paper, spectroscopic and conductimetric studies on the reactions of styrene in the presence of perchloric acid (most in methylene dichloride but some in ethylene dichlorides), both during and after the polymerization, were conducted.
TL;DR: In this article, the amplitude of the steady-state evoked potential (EP) and the sensations of flicker produced by visual stimuli of different modulation depths were compared with the corresponding psychophysical observations for human Ss.
Abstract: Objective physiological measurements (evoked potentials) were compared with the corresponding psychophysical observations for human Ss. Discrepancies were found between the amplitude of the steady-state evoked potential (EP) and the sensations of flicker produced by visual stimuli of different modulation depths. Poor correlations were also found between subjective De Lange curves and amplitude vs frequency curves for the EP under conditions of chromatic adaptation. It is suggested that two classes of EP can be distinguished; one correlates well and the other correlates poorly with sensation.
TL;DR: In this paper, the authors examined the stippled area surrounding the mirror-smooth area at the origin of fracture using an optical microscope and progressive etching, and showed that the area can be regarded as a collection of large numbers of individual local elements of but two basic types.
Abstract: The mist zone, the arc of stippled surface surrounding the mirror-smooth area at the origin of fracture, was examined in detail using an optical microscope and progressive etching. The results show that the stippled area can be regarded as a collection of large numbers of individual local elements of but two basic types, and that microscopic cracks exist below the fracture surface which are related to the structure on the exposed surface.
TL;DR: The position and width of the F band in magnesium oxide have been measured in the temperature range 4-400 °K as mentioned in this paper, and the data have been analysed in terms of the simplest adequate configuration coordinate model.
Abstract: The position and width of the F band in magnesium oxide have been measured in the temperature range 4-400 °K. The data have been analysed in terms of the simplest adequate `configuration coordinate' model. The width results give an effective frequency of 78 × 1012 s-1, which is close to a peak in the phonon density of states and to the value extrapolated from data for the alkali halides. There is evidence that the effective frequency is reduced by about 5% in the excited state of the F centre. The Huang-Rhys factor is about 39, and luminescence is predicted at about 24 eV. The band shape indicates the existence of three small absorption bands on the high-energy side of the main F absorption band. These appear to be associated with the F centre, but their nature is not clear.
01 Nov 1968
TL;DR: In this article, the Arnsbergian of Staffordshire, Derbyshire and Cheshire is described as seven distinctive thin clay beds and beds of clay with pyrite with variable amounts of kaolinite.
Abstract: Summary Seven distinctive thin clay beds and beds of clay with pyrite are described from the Arnsbergian of Staffordshire, Derbyshire and Cheshire. Correlations using these beds are made between the north Staffordshire basin area, Edale, and the Ashover boreholes. The beds are identified mineralogically as K-bentonites consisting of mixed layer, randomly interstratified mica-montmorillonite with variable amounts of kaolinite. The mica polymorph is dioctahedral and is identified as the 1 Md structure of low temperature origin. K-bentonites contrast markedly with the detrital shales above and below them, which contain quartz, chlorite and detrital mica probably of 2M high temperature structure. The K-bentonites are considered to be beds of altered wind-blown ash. Within north Staffordshire and Derbyshire they provide a means of correlation independent of the goniatite horizons.
TL;DR: In this article, an inequality satisfied by the symmetric Ramsey numbers, M(k, k) is deduced, and new upper bounds given for some Ramsey numbers are given.
TL;DR: This paper found that cheating was more prevalent in the Privileged condition than in the equity condition, and that the privilege group did not perceive the situation as unjust, and an explanation in terms of "status congruence" was suggested.
01 Jan 1968
TL;DR: This paper will attempt to illustrate some principles of sensory systems by contrasting features of the organization, and of the functional consequences of that organization, at upper and lower levels of the auditory pathway, and the primary auditory cortex of the cat has been chosen for comparison.
Abstract: This paper will attempt to illustrate some principles of sensory systems by contrasting features of the organization, and of the functional consequences of that organization, at upper and lower levels of the auditory pathway. For this purpose, the second order cell station or ventral cochlear nucleus (VCN), and the primary auditory cortex of the cat have been chosen for comparison. It will be pointed out that at the lower level a simple systematic organization leads to responses of individual neurones which are straightforward as a function of both static and dynamic stimulus parameters, whereas at the cortical level such as systematic organization is not found, and the neurones are particularly responsive to dynamic parameters of the stimulus. Many neurones in the auditory cortex in their responses emphasize certain features of the sound stimulus; they therefore appear to act in a manner analogous to neurones found in the visual cortex [1]; in the auditory case the abstraction is in terms of temporal features of a complex dynamic sound stimulus.
TL;DR: In this article, it was inferred that non-bonded repulsions are of prime importance in determining molecular geometry and the influence of hybridization and the degree of conjugation or hyperconjugation cannot be deduced from bond lengths.
TL;DR: It can be shown that the misorientation produces a linewidth in an axially symmetric system given by the large g value anisotropy in the acid met derivative, and a standard deviation of only 1.6° in angular distribution is sufficient to explain the results obtained.
Abstract: WE have published1 a detailed account of the variation of electron resonance line width in both acid met myoglobin and met myoglobin azide as a function of orientation. We explained the results in terms of a random misorientation of the molecular axes within the single crystals, and showed that, because of the large g value anisotropy in the acid met derivative, a standard deviation of only 1.6° in angular distribution is sufficient to explain the results obtained. These measurements were carried out at Q-band frequencies and the slight deviations from the expected variations were adequately explained in terms of residual broadening mechanisms such as spin–spin interaction and unresolved hyperfine structure. It can be shown1 that the misorientation produces a linewidth in an axially symmetric system given by
TL;DR: A method of synthesizing stop consonants in CV syllables has been investigated and indicates that the conclusions of previous investigators, namely that formant transitions are the main cues for voiced stops and noise burst frequency for voiceless stops, are only partially true.
Abstract: A method of synthesizing stop consonants in CV syllables has been investigated. The data from a perception experiment have been analysed in such a way that the importance of various acoustic features for the perception of stops in front of each of twelve English vowels has been estimated. The results indicate that the conclusions of previous investigators, namely that formant transitions are the main cues for voiced stops and noise burst frequency for voiceless stops, are only partially true. For /d/ and /g/ the importance of the cues depends upon the quality of the following vowel.
TL;DR: It is concluded, despite the limited nature of the evidence available, that there are conditions where learning under conditions of self‐pacing may be less efficient than learning with others and/or under some form of external pacing.
Abstract: For a system to work effectively, each component must act reliably. The student is an essential component in a teaching machine system: in particular, he exerts considerable control over the time constraints of the system. Yet it is unlikely that the • student‐‐because of external and internal pressures‐‐can always work in a reliable way, and so the teaching system may operate in a less than optimum manner. In this paper American and British experiments concerned with this aspect of programmed instruction are reviewed. It is concluded, despite the limited nature of the evidence available, that there are conditions where learning under conditions of self‐pacing may be less efficient than learning with others and/or under some form of external pacing. * Paper presented to the 3rd International Conference on Problems of Programmed Learning and Teaching Machines, Liblice, near Prague, May 1967.
TL;DR: Es sehr wahrscheinlich ist, dass sich Berichte uber die Wirksamkeit dieses Mittlcs vollstandig auf subjektive Erfahrungen stutzen, welche durch Beziehungsandeu-tungen der Bedingungen, unter welchen es eingenommen wurde, ausgelost wurden.
Abstract: Resume— La muscade n'a pas d'effet psychologique dans le domaine du comportement, quand elle est administree dans cette quantite. Il parait tres improbable qu'elle ait quelque effet quand elle est donne dans des quantites plus grandes; donc, il parait tres probable que les rapports publies concernant son efficacite sont bases sur des experiences subjectives causees par la signification des conditions dans lesquelles elle a ete prise.
Zusammenfassung— Muskatnuss, wenn in diesen Mengen verabreicht, hat keinerlei psychologischen Effekt im Bereiche der Verhaltens-Erhebungsauswahl. Auch scheint es hochst unwahrscheinlich, dass bei Verabreichung grosserer Mengen eine Wirkung erzielt wird, weshalb es sehr wahrscheinlich ist, dass sich Berichte uber die Wirksamkeit dieses Mittlcs vollstandig auf subjektive Erfahrungen stutzen, welche durch Beziehungsandeu-tungen der Bedingungen, unter welchen es eingenommen wurde, ausgelost wurden.
TL;DR: In this paper, the characteristics of an ammonia maser operated with a molecular beam which passes through two resonator cavities in succession are discussed, and experimental observations on the oscillation amplitude in the second cavity as a function of tuning of the cavities, separator voltage and beam flux are given in detail and related to previous work.
Abstract: The characteristics of an ammonia maser operated with a molecular beam which passes through two resonator cavities in succession are discussed. Experimental observations on the oscillation amplitude in the second cavity as a function of tuning of the cavities, separator voltage and beam flux are given in detail and related to previous work; some discrepancies are noted.
TL;DR: In this paper, the distribution of Cu in basic igneous rocks (new average 115 ppm) and ortho-amphibolites (New average 107 ppm) was surveyed and compared.
TL;DR: In this article, the double-hump detuning phenomenon of two-cavity molecular beam masers is explained quantum-mechanically, and the detuning process is shown to be reversible.
01 Aug 1968
TL;DR: In this article, a modification of this technique, in which the precipitation is induced by cooling such a solution, is proposed, which has the practical advantages that the lessened need for stirring enhances the stability of the polymer suspension; that the volume of the system stays essentially constant; and that it is less likely for there to be changes in the turbidity of a system after all of the polymers have been precipitated out than with the normal turbidimetric titration.
Abstract: In the technique of turbidimetric titrations for the molecular-weight analysis of polymers, the precipitation of the polymer (phase-separation) is induced by the addition of a precipitant to a very dilute solution of the polymer; in the present paper a modification of this technique, in which the precipitation is induced by cooling such a solution, is proposed. The modification has the practical advantages that the lessened need for stirring enhances the stability of the polymer suspension; that the volume of the system stays essentially constant; that it is less likely for there to be changes in the turbidity of the system after all of the polymer has been precipitated out than with the normal turbidimetric titration; and that it would be much easier to test the reversibility of the precipitation than in such titrations. It also has the advantage from the theoretical viewpoint that, with monodisperse polymer and a single liquid as the medium in which the polymer is initially dissolved, the system becomes a simple binary liquid mixture. TheFlory-Huggins equations have been applied to the case of such a monodisperse polymer at low concentration in a single-liquid medium, and the