Showing papers by "University of Reading published in 1979"
TL;DR: In this paper, a method is given for comparing principal component analyses conducted on the same variables in two different groups of individuals, and an extension to the case of more than two groups is outlined.
Abstract: A method is given for comparing principal component analyses conducted on the same variables in two different groups of individuals, and an extension to the case of more than two groups is outlined. The technique leads to a latent root and vector problem, which has also arisen in the comparison of factor patterns in separate factor analyses. Emphasis in the present article is on the underlying geometry and interpretation of the results. An illustrative example is provided.
515 citations
450 citations
TL;DR: In this article, the anharmonic force field of methane has been refined to fit spectroscopic data from the isotopic species 12CH4, 13 CH4, 12 CH4.
Abstract: The anharmonic force field of methane has been refined to fit spectroscopic data from the isotopic species 12CH4, 13CH4, 12CH4, 12CH3D, 12CHD3 and 12CH2D2. Six of the thirteen cubic force constants have been determined experimentally, the remaining cubic constants being fixed at values derived from ab initio calculations. The quartic force field is very crude, in that only frrrr has been refined. It is concluded however that the cubic and quartic force fields, even though they are subject to limitations, provide a considerable improvement in the experimental determination of the r e structure and the quadratic force field. The equilibrium bond length is found to be r e(CH) = 1·0858 ± 0·001 A.
400 citations
TL;DR: In this paper, the authors reviewed the existing theory and the inclusion of the effects of latent heat release attempted, and showed that such a gravitational destabilization is possible only when a wet bulb potential vorticity is initially negative.
Abstract: In order to study the possible importance of symmetric baroclinic instability in the formation of frontal rainbands, the existing theory is reviewed and the inclusion of the effects of latent heat release attempted. When an atmosphere is rendered symmetrically unstable by latent heat release, it may be said to be conditionally symmetrically unstable. Simple numerical experiments support the extended theory and describe the structure of the finite amplitude cells. These exhibit conditional gravitational instability in preferred linear regions. It is shown that such a gravitational destabilization is possible only when a wet bulb potential vorticity is initially negative. This latter is a necessary and possibly sufficient condition for ‘conditional symmetric instability’ (CSI). Limited comparison with observed frontal rainbands lends some support to the hypothesis that CSI can be a dominant formative mechanism, though more sophisticated numerical modelling and observational studies are required.
356 citations
TL;DR: The decrease in cellular NAD level produced by y-radiation and by N-methyl-N-nitrosourea is proposed to be caused by an increased flux through poly(ADP-ribose) mediated by anincreased activity of poly( ADP- ribose) polymerase, which consequently lowers the cellular NADlevel.
Abstract: Both N-methylN-nitrosourea and γ-radiation lower cellular NAD in mouse leukaemia cells (L-1210) in a dose-dependent way. The minimum NAD level is reached 2 h after a brief exposure to N-methyl-N-nitrosourea, but within 15 min of y-irradiation. The cells remain metabolically active; they are able to recover their control NAD levels and are impermeable to trypan blue.
Several inhibitors of poly(ADP-ribose) polymerase inhibit the drop in cellular NAD caused by these two agents: 2 mM 5-methylnicotinamide, 1 mM theophylline or 1 mM theobromine inhibit the effect of N-methyl-N-nitrosourea on cellular NAD level; 200 uM thymidine, 500 uM 5-methyl-nicotinamide, 500 αM theophylline and 500 αM theobromine prevent the lowering of cellular NAD by y-irradiation. The extent to which the drop in cellular NAD is inhibited is dependent on both the concentration of cytotoxic agent and of polymerase inhibitor. Caffeine will inhibit the drop in NAD but only at 10 mM, while nicotonic acid is ineffective even at this dose.
The activity of poly(ADP-ribose) polymerase in permeabilized cells immediately after y-radiation increases with dose up to 12 krad, giving a maximal 3.4-fold stimulation of the enzyme activity, whereas the degradation of NAD under conditions optimal for NAD glycohydrolase does not change. The activity of the polymerase shows a close temporal correlation with the NAD drop following both γ-radiation and N-methyl-N-nitrosourea. The enzyme activity is maximal when the NAD content is decreasing at the highest rate and has returned to normal levels when it ceases falling.
In permeabilized cells we can distinguish poly(ADP-ribose) polymerase and NAD glycohydrolase activity by their differential response to inhibitors. The polymerase is sensitive to 5-methylnicotin-amide, theophylline, theobromine and thymidine; the NAD glycohydrolase is sensitive to 5-methyl-nicotinamide and theophylline, but not to theobromine and thymidine.
We propose that the decrease in cellular NAD level produced by y-radiation and by N-methyl-N-nitrosourea is caused by an increased flux through poly(ADP-ribose) mediated by an increased activity of poly(ADP-ribose) polymerase. This consequently lowers the cellular NAD level. This hypothesis implies an involvement of (ADP-ribose)n in the cellular response to cytotoxic drugs.
269 citations
TL;DR: In this paper, a permanganic etchant has been developed which reveals lamellar and other fine detail in surfaces of at least three crystalline polyolefines, viz., polyethylene, polypropylene, and isotactic poly(4-methylpentene-1).
Abstract: A permanganic etchant has been developed which reveals lamellar and other fine detail in surfaces of at least three crystalline polyolefines, viz., polyethylene (of both high and low density), isotactic polypropylene, and isotactic poly(4-methylpentene-1). In typical treatments of high-density polyethylene ca. 2 μm of material is removed with defective regions suffering preferential attack. The etchant also discriminates between lamellar orientations, eating deeper where side surfaces of laminae are exposed than on fold surfaces, and between different polymers, attacking isotactic polypropylene more strongly than polyethylene. Comparison with other techniques authenticates the detail exposed and samples appear to be otherwise unaltered by their treatment. Besides normal imaging, it is also possible to use etched samples for transmission diffraction studies in the electron microscope. The method has very considerable application for revealing lamellar details in crystalline polyolefines (which can be chosen to be representative or selective according to the nature of the surface used). Examples are given of a wide variety of melt-crystallized morphologies for the three polymers cited and also of lamellae in a drawn polyethylene sample. It is pointed out that permanganic etching is complementary to the technique of chlorosulfonation used to stain polyethylene in a similar way as bright field microscopy is to dark field.
241 citations
TL;DR: Results suggest that patients who are alexic but not agraphic can name numbers when they are written ideographically but are greatly impaired when the numbers are written alphabetically, which suggests that these different script forms engage different processing mechanisms.
227 citations
TL;DR: It was concluded that access to lexical entries in lexical decision experiments of this sort does not proceed by sometimes or always phonologically recoding visually-presented words.
Abstract: In lexical decision experiments, subjects have difficulty in responding NO to non-words which are pronounced exactly like English words (e.g. BRANE). This does not necessarily imply that access to a lexical entry ever occurs via a phonological recoding of a visually-presented word. The phonological recoding procedure might be so slow that when the letter string presented is a word, access to its lexical entry via a visual representation is always achieved before phonological recoding is completed. If prelexical phonological recodings are produced by using grapheme-phoneme correspondence rules, such recodings can only occur for words which conform to these rules (regular words), since applications of the rules to words which do not conform to the rules (exception words) produce incorrect phonological representations. In two experiments, it was found that time to achieve lexical access (as measured by YES latency in a lexical decision task) was equivalent for regular words and exception words. It was conclu...
213 citations
TL;DR: In this paper, a laser beam is focused on the track by means of a high-aperture objective, and the light which is scattered back through the objective is detected.
Abstract: The form of discs considered has λ/4-deep pits along the track, the spacings and lengths of which are modulated. A laser beam is focused on the track by means of a high-aperture objective, and the light which is scattered back through the objective is detected. The diffraction theory of this system is treated, both for simple periodic and for more complicated forms of disc. Formulas are obtained for the fundamental and harmonics of the read-out signal. The influences of focus error and aberrations are studied, for certain cases of which numerical results are given. Also treated are cross-talk between adjacent tracks and intermodulation between the pit-spacing frequencies and those of the length modulation of the pits.
201 citations
TL;DR: In this article, the response of a baroclinically unstable atmosphere to a localized initial perturbation is examined, using a nonlinear primitive-equation model with spherical geometry.
Abstract: The response of a baroclinically unstable atmosphere to a localized initial perturbation is examined. In a preliminary numerical experiment, using a nonlinear primitive-equation model with spherical geometry, new disturbances grow regularly downstream in broad agreement with a particular type of observed development. The initial disturbance moves downstream, while smaller scale disturbances develop upstream of it—each forming at about the same longitude. Later downstream disturbances have upper level amplitudes significantly larger than found in nonlinear integrations using normal-mode initial conditions. Similar development is found in a quasi-geostrophic model with spherical geometry, and the rate of spreading of the instability is insensitive to the amplitude of the initial perturbation. For the baroclinic instability model considered by Eady the downstream disturbances appear first at the upper surface at a position which moves with a speed close to that of the zonal-mean flow at this surface...
173 citations
TL;DR: The steady response to orography as described by shallow-water equations on the sphere is examined in an attempt to provide insight into the dynamical effects of large-scale orographic features on atmospheric motion as discussed by the authors.
Abstract: The steady response to orography as described by shallow-water equations on the sphere is examined in an attempt to provide insight into the dynamical effects of large-scale orographic features on atmospheric motion. The model equations and the zonal flows and orography used in the study are described. The results for simple mountains and for the earth orography are given. The two-dimensional nature of the horizontal propagation on the sphere is emphasized. The results give interesting indications of the regions of influence of mountains and suggest that quantitative theories of the stationary waves must involve a full representation of the spherical domain.
TL;DR: In this article, the semi-geostrophic equations are used to study the baroclinic instability of jet flows having zero potential vorticity gradient, and the most unstable modes tend to tilt in the horizontal with the ambient shears of the basic zonal flows.
Abstract: The semi-geostrophic equations are used to study the baroclinic instability of jet flows having zero potential vorticity gradient. Normal modes of the linear problems are obtained and it is shown that the most unstable modes tend to tilt in the horizontal with the ambient shears of the basic zonal flows. These most unstable modes are used as initial conditions for integrations of the nonlinear equations. When an upper westerly jet is present, the slightly unrealistic frontogenesis in the Eady mode independent of y (Hoskins and Bretherton, 1972) becomes a realistic cold front development. As the wave grows further a warm front is produced. The same solution may be used for baroclinic growth on a flow with positive vorticity at the surface on the equatorial side of the mode. This exhibits the development of a very different sort of warm front. No cold front is produced. The three kinds of frontogenesis found in these models are analyzed, with emphasis being placed on 1) the ageostrophic horizontal ...
TL;DR: It is possible to remove the innate dormancy of seeds of Rumex crispus L and Rumex obtusifolius L by an initial period of low-temperature stratification, providing the seeds are then transferred to a higher temperature, and maximum germination was obtained.
Abstract: It is possible to remove the innate dormancy of seeds of Rumex crispus L and Rumex obtusifolius L. by an initial period of low-temperature stratification, providing the seeds are then transferred to a higher temperature. The lower the initial temperature within the range 1.5°-15°C, the greater the germination; there is no stratification effect at 20°C. Although 10°C and 15°C were shown to be suitable for both stratification and for the process of germination itself, neither temperature results in any germination if given constantly: a change from a lower to a higher temperature is essential.
The optimum period for stratification depends on two separate processes which occur during the treatment–a rapid loss of innate or primary dormancy and a slower development of induced or secondary dormancy. Within the range 1.5°-15°C the rate of loss of innate dormancy appears to be independent of light and is probably independent of temperature. In contrast, the rate of induction of secondary dormancy increases with increase in temperature, and is more rapid in the dark than the light. The rate of induction of secondary dormancy during stratification is greater in R. crispus than in R. obtusifolius. As a consequence, maximum germination was obtained in both species after stratification at 1.5°C in the light, the optimum period of treatment being about 4 weeks in R. Obtusifolius and 6 weeks in R. crispus, while the maximum germination obtained and the optimal period of stratification decrease in both species with increase in stratification temperature.
TL;DR: The notion of punishment is both ancient and widely held in philosophy and it has been argued that failure to punish is unfair to those who practise self-restraint and respect the rights of others.
Abstract: One of the functions of philosophy is to combat ambiguity and muddle. Yet in discussions of the justification of punishment, philosophers persist in talking of ‘retribution’ and ‘retributive theory’ as if the labels stood for something relatively simple and straightforward. Exactly how or why suffering something unpleasant should count as payment for an offence is left unexplained; but it has to be admitted that the notion is both ancient and widely held. Kant, universally regarded as a retributivist, asserts that the reason why punishment is imposed must always be because the individual on whom it is inflicted has committed a crime. Failure to punish is unfair to those who practise self-restraint and respect the rights of others. The logic of justification implied by Kant seems heavily tied up with the Old Testament notions of sacrifice and placation. Murder involves blood guilt for which an angry God will take vengeance.
TL;DR: In this article, the authors suggest that the research intensity is an important influence on sourcing policy, particularly through its effect on the firm's internal exports, and suggest that this is the case for many companies.
Abstract: The sourcing policy of a multinational enterprise is the result of the firm's decisions as to which of its production facilities shall service its various final markets. We can thus speak of an international network linking production to markets. Critical determinants of this policy are the firm's size, industry characteristics, and influences deriving from the firm's natioanality of ownership. We suggest that the research intensity is an important influence on sourcing policy, particularly through its effect on the firm's internal exports.
TL;DR: The results indicate that two photoreceptors may normally be involved in the control of seedling growth but their relative importance varies greatly between species.
Abstract: The effect of blue light on hypocotyl extension in de-etiolated seedlings of lettuce, cucumber and tomato was investigated under conditions which precluded the involvement of phytochrome. Small but highly inhibitory amounts of blue light were added to a high intensity background illumination from low pressure sodium lamps. A log-linear response for inhibition of hypocotyl extension against the blue light fluence rate was obtained for lettuce and cucumber, and inhibition in tomato was also related to the blue light fluence rate. The added blue light did not alter phytochrome photostationary state and its effect was independent of the total fluence rate. Growth inhibition by Pfr could be demonstrated in tomato and cucumber but not in lettuce. The results indicate that two photoreceptors may normally be involved in the control of seedling growth but their relative importance varies greatly between species.
TL;DR: In this article, approximate solutions for wave speed given by equations reduce the number of arithmetic operations required during a refraction calculation and the precise saving depends on the algorithms presently in use, but a time saving of about half appears typical.
Abstract: Approximate solutions for wave speed given by equations reduce the number of arithmetic operations required during a refraction calculation. The precise saving depends on the algorithms presently in use, but a time saving of about half appears typical.
TL;DR: The systematic fractional replicate (SFS) as mentioned in this paper is a new screening design which isolates the most important factors in experiments involving a large number of significant factors and interactions, and can be arranged in blocks of any size without altering the analysis.
Abstract: SUMMARY This paper describes a new screening design which isolates the most important factors in experiments involving a large number of significant factors and interactions. The design is called the systematic fractional replicate design. For an n-factor experiment 2n + 2 units are required, and the results indicate whether each factor has odd and even order effects. No prior assumptions are made about the nature or absence of interactions. The design can be arranged in blocks of any size without altering the analysis.
TL;DR: The breeding behaviour of fallow deer is described and shown to make a father-daughter incest likely and an inclusive fitness argument is developed to account for incest in polygynous species.
Abstract: It is assumed by many zoologists that most animals avoid inbreeding because of the associated deleterious effects. The breeding behaviour of fallow deer is described and shown to make a father-daughter incest likely. By treating incest as a form of altruistic behaviour on the part of females, an inclusive fitness argument is developed to account for incest in polygynous species. It is shown that a substantial (1/3) reduction in individual fitness is required if incest is to be selected against.
01 Jul 1979
TL;DR: The attempt to provide for typographic design generally applicable to research findings is questioned, and alternatives are suggested to the approaches of the book and of “traditional” typography.
Abstract: The context of the book and its contents are outlined; its aim of providing guidelines derived from empirical research for the design of instructional text is emphasized One of the book's particular proposals-structuring of text by the controlled use of vertical space-is examined, and the relative merits of vertical and of horizontal space are discussed The review then presents the book's arguments from research evidence for certain design practices These arguments are found to be, typically, ease of production and cost-benefit, rather than the justification of benefit for the user The book is held to be putting forward a programme-not merely a set of guidelines-the chief characteristic of which is simplicity of form, in contrast to what the book sees as the irrational forms of “traditional” typography The review considers some possible virtues of “traditional” typography, and, in the design of some tabular matter, alternatives are suggested to the approaches of the book and of “traditional” typography In a concluding evaluation of the book, the attempt to provide for typographic design generally applicable to research findings is questioned Alternative paths for research in this field are suggested
TL;DR: It is shown that interlaced meshes or mesh and submeshes may be employed to gain further computational economy and the algorithm and performance of a three dimensional implementation of the transform algorithm is given.
TL;DR: In this paper, a classification of Jurassic marine shales is proposed based on an analysis on the Toarcian (Upper Lias) sediments of the Lower Jurassic of Yorkshire, Great Britain.
TL;DR: The scallop Chlamys varia (L.) was found associated with an enveloping epizoitic growth of the sponge Halichondria panicea (Pallas) and was protected against predatory starfishes by the sponge which interfered with the attachment of tube feet and made the vulnerable byssal opening and valve margins inaccessible to the predator's gastric membranes.
01 Mar 1979
TL;DR: The saponin fractions of defatted lupinseed meals can be extracted by means of 20 per cent aqueous ethanol as discussed by the authors, which affords, from each species, a characteristic range of sapo...
Abstract: The saponin fractions of defatted lupinseed meals can be extracted by means of 20 per cent aqueous ethanol. Acid hydrolysis of the extract affords, from each species, a characteristic range of sapo...
TL;DR: A scheme to account for the phytochrome responses of dark grown and green plants is presented and it is proposed that both Pfr and the photoconversions of phYtochrome are effectors of phy tochrome action and interact to promote the observed responses.
Abstract: A scheme to account for the phytochrome responses of dark grown and green plants is presented. In contrast to some other models (e.g. Smith, 1970; Schafer, 1975) it is proposed that both Pfr and the photoconversions of phytochrome are effectors of phytochrome action and interact to promote the observed responses. Under conditions where Ptot is not strongly wavelength dependent (e.g. with short pulses of light and in plants grown for prolonged periods in the light), responses will be predominantly related to Pfr concentration. Where Ptot is the major wavelength dependent variable (e.g. in the ‘high irradiance reaction’ of etiolated seedlings) it is proposed that the photoconversion process itself predominates in controlling the ultimate response. Some responses predicted by the scheme are compared with relevant published data.
TL;DR: In this article, the relative and absolute line intensities for the ν3 bands of the 12C and 13C isotopic varieties of methane have been measured using a tunable difference-frequency laser spectrometer.
TL;DR: In this article, the Na-Mg and Na-Ca exchange isotherms were determined at electrolyte concentrations of 500, 50, 5 and 1 meq per litre for illite, vermiculite and montmorillonite.
Abstract: Summary
Na-Mg and Na-Ca exchange isotherms were determined at electrolyte concentrations of 500, 50, 5 and 1 meq per litre for illite, vermiculite and montmorillonite and for three soils containing illite and montmorillonite. This enabled comparisons to be made of clay swelling, dispersion and soil hydraulic conductivity changes between the Na-Mg and Na-Ca systems at known SAR, ESP and electrolyte concentration.
Na-Mg montmoriUonite and a montmorillonitic soil behaved identically to the Na-Ca systems at the same ESP and electrolyte concentration: there was no specific effect. At the same SAR, the higher ESP in the Na-Mg system caused greater changes than in the Na-Ca systems. The Na-Mg vermiculite, illite, illitic soil and mixed illite-montmorillonitic soil showed greater changes than the Na-Ca systems at the same ESP, and there was a specific effect. At the same SAR, the higher ESP in all the Na-Mg systems apart from vermiculite increased the differences, but for vermiculite with a lower ESP, the differences were reduced. The lack of a specific effect for montmorillonite is probably related to the demixing of cations with the divalent ions concentrated on the non-swelling (internal) surfaces of the crystals.
TL;DR: In this article, a theory of ethnic separatism is proposed for ethnic self-identity in the context of ethnic and racial studies, which is based on the concept of ethnicity.
Abstract: (1979). Towards a theory of ethnic separatism. Ethnic and Racial Studies: Vol. 2, No. 1, pp. 21-37.
TL;DR: The pollen grain tryphine, believed to be important in the adhesion process, has been shown to differ in mobility following self- and cross-pollination when observed using fluorescent probes.
Abstract: Quantitative studies of the adhesion of pollen grains to the stigma in Brassica oleracea revealed that self-pollen is initially less firmly bound than cross-pollen. The pollen grain tryphine, believed to be important in the adhesion process, has been shown to differ in mobility following self- and cross-pollination when observed using fluorescent probes. The hydration of the pollen grains has been investigated in vitro by measuring the changes in shape, volume and fresh weight of the imbibing grains. Whilst little change in volume could be detected there was a considerable increase in fresh weight together with a change of shape. The significance of these events, which occur prior to pollen germination, is discussed in relation to their effect upon subsequent germination and expression of self-incompatibility.