Showing papers by "University of East Anglia published in 1969"
TL;DR: In this article, the overall elastic moduli of some solid composite materials are evaluated, first by bounding them precisely, and secondly by a self-consistent estimate, at both random and aligned orientations, and at arbitrary volume concentration.
Abstract: The overall elastic moduli of some solid composite materials are evaluated, first by bounding them precisely, and secondly by a ‘self-consistent’ estimate. Transversely isotropic inclusions of ‘needle’ and ‘disc’ shapes are particularly considered, at both random and aligned orientations, and at arbitrary volume concentration.
464 citations
TL;DR: In this article, a simple theoretical treatment assuming "trapping" of positrons by defects reproduces the essential features of temperature dependence of positron lifetimes in some metals, showing a marked increase in lifetimes below the melting point.
215 citations
TL;DR: In this paper, two experimental approaches have been used to determine whether the internal fibres of the amphibian lens have intact membranes, one involves an analysis of the potential transients obtained when potassium is substituted for sodium in the external medium and the other involves a correlation of lens electrical resistance with depth of penetration of the measuring electrodes.
98 citations
TL;DR: In this paper, the authors classified reactions of N-alkoxy and N-acyloxy heterocycles with nucleophiles into four types: hard/soft, soft, hard and soft.
84 citations
TL;DR: It is shown that graphs of ion efflux against external concentration which can be fitted by a Michaelis-Menten equation do not constitute evidence for the presence of exchange diffusion; graphs of similar shape can be obtained if the flux is simply diffusional.
Abstract: I. The effects of different external media on the sodium and chloride efflux in Artemia salina , the brine shrimp, have been observed, using animals acclimatized to sea water. In sea water, both sodium and chloride fluxes across the epithelium are approximately 7,000 pmole cm. -2 sec. -1 . 2. Sodium efflux drops markedly in sodium-free media, and chloride efflux falls in chloride-free media; the two effects are independent, and are not due to changes in external osmolarity. 3. The decreases in sodium efflux can be explained by changes in electrical potential difference and diffusional permeability; exchange diffusion of sodium does not occur. 4. Approximately 70% of the chloride efflux is due to exchange diffusion, and most of the remainder is due to active transport. 5. It is shown that graphs of ion efflux against external concentration which can be fitted by a Michaelis-Menten equation do not constitute evidence for the presence of exchange diffusion; graphs of similar shape can be obtained if the flux is simply diffusional. 6. The drinking rate, determined from the rate of uptake of 131 I-polyvinylpyr-rolidone, is 36 pl. sec. -1 , or 2.0% body weight hr. -1 . 7. The diffusional influx of water is 240 pl. sec. -1 .
80 citations
TL;DR: The living insect restricts its water loss in low humidities by means of a permeability barrier which is disrupted during uptake in high humidities and is progressively lost on death.
Abstract: 1. Uptake of water from the atmosphere by previously desiccated, starved Thermobia domestica is related to the % relative humidity, and occurs in and above 63% R.H. between 17 and 37° C. Losses occur in and below 43% R.H.
2. Uptake is often, though not invariably, arrested during even brief periods of locomotor activity.
3. Recovery from desiccation proceeds to the same level of body-water content in all humidities above the ‘critical’ value. Equilibrium is reached more rapidly in the higher temperatures and humidities.
4. The equilibrium level attained is the same as that found in control insects, and it does not change when the insect is transferred from one high humidity to another.
5. During periods of relatively large dry-weight losses, a greater proportion of water is retained in the body, providing some volume regulation.
6. The living insect restricts its water loss in low humidities by means of a permeability barrier which is disrupted during uptake in high humidities and is progressively lost on death. This restriction is not dependent upon the continued activity of the uptake mechanism.
62 citations
TL;DR: The properties of a system consisting of a thin phospholipid film separating two electrolyte solutions containing 1mm 2,4-dinitrophenol have been studied and the maximum conductance was found to be 1.4×10−5 mhos cm−2 at pH 4.2.
Abstract: The properties of a system consisting of a thin phospholipid film separating two electrolyte solutions containing 1mm 2,4-dinitrophenol have been studied. Both the variation of electrical conductance as a function of pH, keeping the pH the same on both sides of the membrane, and the nonlinear variation of electrical potential difference as a function of pH difference across the membrane have been explained in terms of lipid-soluble complexes of the typeXP
2
−
whereX is a cation andP dinitrophenate. The maximum conductance was found to be 1.4×10−5 mhos cm−2 at pH 4.2.
57 citations
TL;DR: In this article, a fresh look at available estimates of the rates of erosion suggests that landforms have taken longer to evolve than has been thought, which suggests that erosion has been more complex than previously thought.
Abstract: A fresh look at available estimates of the rates of erosion suggests that landforms have taken longer to evolve than has been thought.
53 citations
TL;DR: In this paper, a constant field theory was applied to the unidirectional flux data, and the ratio PNa/PK was found to be 0.07, where PNa is defined as the ratio of the current passing through the lens to the passive movement of the ions.
52 citations
TL;DR: In this paper, three parallel bands have been observed for each of the gas phase complexes H 3 N ⋯HCN and D 3 N⋯DCN corresponding to the fundamental C-H(C-D) and CN stretching and the symmetric NH 3 (ND 3 ) deformation vibrations.
51 citations
TL;DR: The isolation of a phage capable of effecting transduction in certain strains of Klebsiella aerogenes is described, which is likely to extend greatly the considerable amount of information accumulated as a result of biochemical studies with organisms of the KleBSiella group.
Abstract: PHAGE-MEDIATED transduction has been reported in strains of four genera of Enterobacteriaceae: Salmonella, Escherichia, Shigella, and Proteus1. Clarke2 described possible transduction of a single Klebsiella pneumoniae auxotroph to prototrophy, but this has not been confirmed. A search of the literature failed to reveal any other report of transduction involving a member of the genus Klebsiella. Indeed, there does not seem to be any previous report of a system permitting transfer of chromosomal genetic determinants between strains of Klebsiella. This is rather surprising, for genetic studies might be expected to extend greatly the considerable amount of information accumulated as a result of biochemical studies with organisms of the Klebsiella group (often still referred to as Aerobacter aerogenes despite the taxonomic confusion which this name perpetuates3). Examples of studies which might well be enhanced by the availability of a system of genetic analysis are those on exopolysaccharide biosynthesis by Klebsiella strains (unpublished work of I. W. S. and J. F. W.); nitrate assimilation4; polyphosphate accumulation and degradation5; and many others. This communication describes the isolation of a phage capable of effecting transduction in certain strains of Klebsiella aerogenes.
TL;DR: Though a generative grammar can represent all the grammatical knowledge a speaker has and can account for how he is able to understand sentences, yet such a grammar cannot account forHow a speaker is ableto understand semi-sentences.
Abstract: Katz's statement of the core of the problem of ungrammaticalness is worth quoting at length:
‘The knowledge that enables a speaker to understand sentences – his knowledge of the rules of the grammar – must be identically the knowledge that enables him to understand semi-sentences, for semi-sentences are understood in terms of their well-formed parts. Moreover, the knowledge a speaker uses to recognize the respects in which a semi-sentence is ungrammatical is also his knowledge of grammaticality: knowledge of the grammatical rules is here employed to discover instances of their violation.…
TL;DR: The coupling constants of the cis and trans isomers of 2-ureidocyclohexane carboxylic (UCHA) and of the erytho and threo isomer of 2,3-diphenyl-3-uridopropionic acid (DPhUPA) with gauche hydrogens are preferred as discussed by the authors.
TL;DR: In this paper, the rotational isomeric configurations of substituted paraffins from measurements of infra-red and nuclear magnetic resonance (NMR) spectra are summarised.
TL;DR: From an analysis of the total cation and mobile anion content of the lens it seems likely that there are at least 100 m m of fixed negative charges within the lens, which would cause the internal osmolarity to exceed that of the aqueous humor causing the lens to swell.
[...]
TL;DR: The effect of pH on the co-operative activation of the NAD-specific isocitrate dehydrogenase from pea mitochondria by isoc itrate is shown and similarities between the binding of isocItrate and citrate are demonstrated.
Abstract: 1. The effect of pH on the co-operative activation of the NAD-specific isocitrate dehydrogenase from pea mitochondria by isocitrate is shown. 2. The interlinked effects of pH on the affinity of the NAD-specific isocitrate dehydrogenase for isocitrate and the dependence of the pH optimum on the substrate concentration are presented. 3. A consideration of the conditions of pH and substrate concentration under which citrate activates the NAD-specific isocitrate dehydrogenase demonstrates similarities between the binding of isocitrate and citrate. 4. A comparison of the effects of citrate and pH on the gross structure of the enzyme is investigated by density-gradient centrifugation. 5. The kinetic interpretations of these results are briefly considered. 6. The metabolic significance of these studies is discussed.
TL;DR: Evidence is presented that pyruvic decar boxylase from plants also catalyses the decarboxylation of glyoxylate, and the suggested explanation of this anomaly is the removal of a product (formaldehyde) from the enzyme.
TL;DR: The potassium efflux is not sensitive to short-term exposures to solutions containing 2,4 dinitrophenol (DNP) or ouabain, and this confirms that the potassium ions move outwards passively across the membranes.
TL;DR: With the exception of the liver and kidney, organ cultures showed good preservation for up to six days in vitro using a medium supplemented with 10% fetal calf serum, and values for MI comparable with or even higher than in vivo were obtained.
Abstract: Using the Colcemid technique, the mitotic incidence (MI) was measured in the epidermis, lung, spleen, liver, kidney and ovarian follicular cells of metamorphosed, immature Xenopus laevis laevis. The MI was higher at 25°C than at 20°C, and there was a significant ranking correlation between organs in respect of the MI in different animals. With the exception of the liver and kidney, organ cultures showed good preservation for up to six days in vitro using a medium supplemented with 10% fetal calf serum, and values for MI comparable with or even higher than in vivo were obtained.
TL;DR: This communication reports on the enzymatic transfer of methyl groups from S-adenosyl methionine to the ϵ-N of lysine in histones IIb and III in isolated pea chromatin.
TL;DR: In this article, the spectral analysis of two cyclobutenes and two cyclometrically complex cyclobutanes with complex spectra is discussed in some detail, and a considerable amount of information about relative signs, as well as magnitudes, of (H, F) and coupling constants is obtained.
01 Aug 1969
TL;DR: Foraminiferal assemblages obtained from five sites are mostly dominated by Elphidium clavatum and indicate middle Pleistocene interglacial conditions; in all forty-five species of foraminifera are recorded as mentioned in this paper.
Abstract: Summary Marine clay appearing to crop out between the Chalk and a boulder clay resembling the Purple Till of Holderness has been sampled by gravity coring on the flanks of the Inner Silver Pit between 53° 24·8′ to 53° 30·2′ N and 0° 40·8′ to 0° 41·8′ E. Foraminiferal assemblages obtained from five sites are mostly dominated by Elphidium clavatum and indicate middle Pleistocene interglacial conditions; in all forty-five species of foraminifera are recorded. Pollen indicating zones IIIb and IV of the temperate Hoxnian stage is present in the same
TL;DR: In this article, the authors studied the propagation of a sinusoidal wave of small amplitude in an initially isotropic viscoelastic solid, which is subjected to a static pure homogeneous deformation, and derived the secular equation for a plane wave propagating an arbitrary direction with respect to the principal directions of the static deformation.
Abstract: The propagation of a sinusoidal wave of small amplitude in an initially isotropic viscoelastic solid, which is subjected to a static pure homogeneous deformation, is discussed The secular equation for a plane wave propagating an arbitrary direction with respect to the principal directions of the static deformation is derived The complex slownesses corresponding to propagation along the principal axes of the static strain are found Relations are obtained between these and the principal stresses associated with the static deformation, which generalize earlier formulas obtained by Ericksen for elastic materials
TL;DR: In this paper, the twenty-one independent elastic constants in the general linear homogeneous anisotropic elastic body may be measured in a simple systematic manner by using a static homogeneous deformation field called "pure extension".
Abstract: A method is given whereby the twenty-one independent elastic constants in the general linear homogeneous anisotropic elastic body may be measured in a simple systematic manner by using a static homogeneous deformation field called “pure extension”. Two types of test are used throughout.