Showing papers by "Lancaster University published in 1974"
TL;DR: In this article, expressions for flux-pinning in type II superconductors are derived from considerations of the nature of the interaction between individual flux-lines and pinning-centres, and of the geometry of th...
Abstract: Expressions for flux-pinning in type II superconductors are derived from considerations of the nature of the interaction between individual flux-lines and pinning-centres, and of the geometry of th...
1,011 citations
TL;DR: An up-to-date Table of the monthly and seasonal means representative of the air over central England from 1659 onward, incorporating some minor revisions and extensions of the earlier Table (Manley 1953 and 1959) is provided in this paper.
Abstract: An up-to-date Table is provided of the monthly and seasonal means representative of the air over central England from 1659 onward, incorporating some minor revisions and extensions of the earlier Table (Manley 1953 and 1959). Comments on its construction, and on the prospect of further extension backward in time, are added.
939 citations
TL;DR: In this paper, it was shown that non-Newtonian properties of lava are mainly responsible for the shape of lava flows and not just the surface properties of the lava itself.
Abstract: Summary It is postulated that lavas are non-Newtonian liquids with a yield stress and that it is the yield stress which determines flow dimensions. An appropriate theory was developed for the unconfined flow of ideal Bingham liquids on inclined planes. The occurrence of structures similar to IevCes on lava flows was predicted. The theory was verified by laboratory measurements on flows of suspensions of kaolin. These flows showed similarities to lava flows. Data from lava flows was also found to be in general agreement with the theory which was then used to interpret the shapes of two lunar lava flows. It was possible to estimate yield stresses and flow rates for these lavas. 1. Effects limiting the flow of lava Lava flows show great variations in size, shape and surface features. The final form of a flow must be determined by the physical properties of the lava, its temperature and rate of extrusion and local conditions such as gravitational field strength and topography. The aim of the work presented in this paper is to isolate the parameters which have the greatest effect on flow morphology and to elucidate the relationship between the conditions at the start of a flow and the final form of the flow. At present there is no detailed knowledge of this kind but, were it available, the value of air- and satellite-photographs of lava flows would be greatly enhanced. The hypothesis on which this work is based is that flowing lava is a non-Newtonian liquid and it is its non-Newtonian properties which are mainly responsible for the shapes of flows. If lava were an ideal Newtonian liquid it would flow downhill and would continue to flow even after the supply at the vent had ceased until it ponded in a depression. Furthermore the flow would spread laterally until it was restricted by topography or until surface tension prevented spreading by which time it would be extremely thin. Observations show that lava does not behave like this. Commonly it comes to rest on a slope as soon as the supply of fresh lava ceases and many flow fronts are high and steep although unconfined by topographic features. It is clear that there is some process which limits the flow of lava, brings it to rest on slopes and prevents its lateral spreading. The most obvious and apparently generally accepted process is the solidification of lava due to cooling. For this to be a feasible process the time taken for the development of a strong enough skin to prevent lateral motion must be realistic. The solid skin of a flow experiences an outward force due to the hydrostatic pressure of the lava and this must be balanced by an inward force which is the result of tension in the curved skin. If the skin can withstand the tension the lava will not flow laterally.
447 citations
TL;DR: In this article, it was argued that the compositions of the magmas which formed these obsidians and those which subsequently crystallised were similar as regards the major oxides SiO2, Al2O3, FeO + Fe2O+Fe2O 3, Na2O and K2O.
Abstract: Four-hundred and twenty-one analyses of quartz-normative, peralkaline, extrusive rocks have been collected from the literature and from unpublished sources and are used to examine chemical variation in this group of rocks. Comparisons are particularly made between the full body of data and the variations recorded in the non-hydrated obsidians alone byMacdonald andBailey (1973). It is argued that the compositions of the magmas which formed these obsidians and those which subsequently crystallised were similar as regards the major oxides SiO2, Al2O3, FeO + Fe2O3, Na2O and K2O.
278 citations
TL;DR: This paper reviewed the literature on the relationship between academic performance in higher education and motivation and study habits and the distinction between goal-oriented and intrinsic motivation is used to clarify the meaning of previous studies.
Abstract: The first part of the article reviews the literature (mainly British) on the relationships between academic performance in higher education and motivation and study habits. The distinction between goal-orientated and intrinsic motivation is used to clarify the meaning of previous studies. Among the investigations of study habits, the dimension of syllabus-boundness/syllabus-freedom helps to relate psychiatric work on study difficulties to research using self-report inventories.
87 citations
TL;DR: The amount of store necessary to operate a dynamic storage allocation system, subject to certain constraints, with no risk of breakdown due to storage fragmentation, is considered and upper and lower bounds are given.
Abstract: The amount of store necessary to operate a dynamic storage allocation system, subject to certain constraints, with no risk of breakdown due to storage fragmentation, is considered. Upper and lower bounds are given for this amount of store, both of them stronger than those established earlier. The lower bound is the exact solution of a related problem concerning allocation of blocks whose size is always a power of 2.
69 citations
TL;DR: In this article, six magnetic variometers were installed at sites along a 300 km east-west line, crossing the eastern branch of the East African Rift Valley near the Equator, during which time four magnetic disturbances were recorded.
Abstract: Summary
Six magnetic variometers were installed at sites along a 300 km east-west line, crossing the eastern branch of the East African Rift Valley near the Equator. The instruments were operated from March to May 1971, during which time four magnetic disturbances were recorded.
Transfer functions have been computed for each station, and are presented both as real and imaginary induction arrows and in an alternative ‘maximum and minimum’ form. They show that a relatively shallow concentration of induced current flows along the axis of the rift valley. However, the anomaly is not symmetric, and the phase of the response shows a complex behaviour on the east side of the Rift.
The computer program of Jones and Pascoe has been used to compute the response of two-dimensional conductivity models. The type of model that fits the experimental data involves a strip of high conductivity material at a depth of no more than 20 km beneath the floor of the rift with, in addition, a thick slab (100 km) of material of more moderate conductivity at a depth of 50 km beneath the eastern flanks of the rift. The lateral extent of this slab was not precisely defined by the 1971 experiment, but it may well be several hundred kilometres.
The two regions of high conductivity are interpreted as zones of partial melting in the upper mantle. Their positions coincide with the regions of most recent (late Quaternary) volcanism.
59 citations
57 citations
57 citations
TL;DR: The chorion and perivitelline fluid of Atlantic salmon eggs were investigated by chemical and physical methods and the process of water uptake could be osmotically inhibited by adding high molecular weight substances to the external medium.
Abstract: The chorion and perivitelline fluid of Atlantic salmon eggs were investigated by chemical and physical methods. The turgor pressure of the chorion in water hardened eggs was about 60 mm Hg. With newly stripped eggs in fresh water a similar pressure was achieved after about one day but the process of water uptake could be osmotically inhibited by adding high molecular weight substances to the external medium. Perivitelline fluid contained about 58 % water the remainder being a high molecular weight substance consisting mainly of protein but also containing significant quantities of carbohydrate and lipid. The functions of the chorion are discussed with reference to salmon eggs and also to marine pelagic fish eggs such as those of the plaice.
51 citations
TL;DR: In this article, the attitudes of 600 second-year and fifth-year grammar school pupils towards their school subjects were investigated using a repertory grid developed specifically for this purpose.
Abstract: Summary. The attitudes of 600 second-year and fifth-year grammar school pupils towards their school subjects were investigated using a repertory grid developed specifically for this purpose. Attitude dimensions of ‘interest,’ ‘difficulty,’ ‘freedom,’ and ‘social benefit’ were isolated. Rank orders of mean scores of pupils on these four scales were produced together with inter-correlations indicating the extent to which attitudes were specific to particular school subjects.
TL;DR: Partial amino acid analysis of the materials of the selachian egg capsule indicated a composition markedly different from pure collagens, and to date there has been no report of fibrous periodicity in selACHian egg capsules.
Abstract: IN spite of a wealth of information relating to the composition and structure of mesenchymal collagens, relatively little is known about the so-called ‘secreted’ collagens of epithelial origin which are much more limited in distribution. The materials of the selachian egg capsule has been classified as such a collagen though this claim is based on a poorly oriented high angle X-ray diffraction pattern obtained from skate egg capsules1 and on the colorimetric detection of hydroxyproline in hydrolysates of the same material2. Partial amino acid analysis of this material2 indicated a composition markedly different from pure collagens. To date there has been no report of fibrous periodicity in selachian egg capsules.
TL;DR: In this paper, a dirty-limit version of the Gor'kov theory is used to calculate numerically the selfconsistent structure and free energy of isolated vortices and of the vortex lattice in the circular cell approximation at arbitrary temperature and Ginzburg-Landau parameter κ.
Abstract: A recent dirty-limit version of the Gor'kov theory is used to calculate numerically the self-consistent structure and free energy of isolated vortices and of the vortex lattice in the circular cell approximation at arbitrary temperature and Ginzburg-Landau parameter κ. This yields the lower critical fieldHc1, the magnetization curve, the electronic specific heat, and the density of states at the Fermi surface. The results are discussed and compared with experiments.
TL;DR: The largest volumes of peralkaline silicic rocks are found in areas of epeirogenic uplift and rift formation on the continents, but they may also form in several other tectonic settings, such as the oceanic islands, during the later stages of orogenic cycles, as isolated occurrences in active mobile belts, and in extensional tectonics at or near continental plate margins as mentioned in this paper.
Abstract: The largest volumes of peralkaline silicic rocks are found in areas of epeirogenic uplift and rift formation on the continents, but they may also form in several other tectonic settings, such as the oceanic islands, during the later stages of orogenic cycles, as isolated occurrences in active mobile belts, and in areas of extensional tectonics at or near continental plate margins Their emplacement is effected during periods of dominantly tensional stresses
TL;DR: The subcuticular phase in the development of Rhynchosporium leaf blotch of barley was studied by scanning and transmission electron microscopy and found that hyphae grow beneath the cuticle in the region which is rich in pectic substances.
Abstract: The subcuticular phase in the development of Rhynchosporium leaf blotch of barley was studied by scanning and transmission electron microscopy. After direct penetration of the cuticle, hyphae grow beneath the cuticle in the region which is rich in pectic substances, often growing along the line where adjacent epidermal cells meet. The cuticle over the hyphae is stretched but not ruptured and there is only localized disruption of the cell wall. Appositions of cell wall material occur on the inner surface of the epidermal cell wall. Close to subcuticular hyphae, short lengths of the plasmalemma of epidermal cells may be separated from the cell wall. The epidermal cells collapse and, in the underlying mesophyll cells, the chloroplasts show degenerative changes.
TL;DR: It is concluded that the observed potentials result from the active transport of ions across the branchial epithelium.
Abstract: Measurements of the potential between the external medium and the body fluids of flounders placed in an external medium of Ringer solution have revealed the presence of a steady potential averaging 4·1 mV, inside positive. Isolated gill preparations perfused and bathed in identical Ringer solutions show a similar potential (averaging +6·9 mV) and demonstrate that it cannot be a diffusion potential. Experiments with the perfused preparation have further shown that this potential is dependent on metabolism and is markedly reduced by concentrations of ouabain down to 10−5M (see Fig. 3), thiocyanate down to 5×10−3M (see Fig. 4) and in the absence of potassium in the external medium. It is concluded that the observed potentials result from the active transport of ions across the branchial epithelium.
TL;DR: Sorghum plants that had been subjected to different degrees of water stress were examined for the occurrence of endogenous compounds capable of inducing stomatal closure, i.e. “antitranspirants”.
Abstract: Sorghum plants that had been subjected to different degrees of water stress were examined for the occurrence of endogenous compounds capable of inducing stomatal closure, i.e. “antitranspirants”. Acidic extracts contained increased amounts of abscisic acid (ABA) as the amount of stress increased, but another highly active compound easily distinguished from ABA also accumulated. This compound, also found in neutral extracts, was probably all trans-farnesol, an isoprenoid alcohol which, like ABA, is a sesquiterpenoid. Highly dilute solutions of “commercial” farnesol induced stomatal closure when applied to isolated epidermis of Commelina.
Journal Article•
TL;DR: In this article, a meridional chain of riometers in the auroral zone was used to detect the onset of an auroral absorption substorm in the form of a weak bay-like event, moving slowly equatorward.
Abstract: Observations with a meridional chain of riometers in the auroral zone show that the onset of an auroral absorption substorm is usually preceded by weak activity. This activity sometimes takes the form of a weak bay-like event, moving slowly equatorward. Its velocity (typically 200–500 m/sec) is consistent with the inward convection of energetic plasma in the magnetosphere— that is, with E × B drift in an electric field of about 1.3 mV/m. The bay intensifies as it moves, indicating energization of the plasma during convection.
TL;DR: There appears to be a selective change in the permeability of the plastid envelope during development which differs according to the specific substrates used.
Abstract: The distribution of 3H-labelled mevalonic acid, leucine and tyrosine between plastids and extraplastidic tissue in illuminated, etiolated seedlings was studied using electron microscope autoradiomicrography and radioassay of specific plastidic and extraplastidic components. There appears to be a selective change in the permeability of the plastid envelope during development which differs according to the specific substrates used.
TL;DR: It is confirmed that fusicoccin stimulates stomatal opening and the entry of potassium into the guard cells and a physiological role for the subsidiary cells in regulatingStomatal movements is strongly indicated.
Abstract: SUMMARY
The fungal toxin, fusicoccin, induces wilting when applied to uninfected plant material. We have confirmed that fusicoccin stimulates stomatal opening and the entry of potassium into the guard cells. When detached epidermis of Commelina communis is placed in a potassium-free medium containing 10 μM fusicoccin, the stomata open widely and potassium accumulates in the guard cells, demonstrating that sufficient endogenous potassium is available.
The failure of stomata to open on isolated epidermis is discussed. It is suggested that the subsidiary cells respond to a wound hormone produced after stripping off the epidermis, the effect of which is to block the normal route taken by potassium as it moves into the guard cells. A physiological role for the subsidiary cells in regulating stomatal movements is thus strongly indicated.
Fusicoccin is able to overcome the effect of those environmental factors, darkness and high CO2 concentrations, which normally inhibit stomatal opening. Evidence is presented that, in this case, it must act within the guard cells and not only on the subsidiary cells. The time of exposure to the toxin required for a subsequent opening response of the stomata is very short. Stomata in contact with 10 μM fusicoccin for 1 min open almost as widely as those exposed to the same concentration for 2 h.
TL;DR: In this article, the amplitude fading of the 137 MHz signals from the geostationary satellite, Intelsat IIF3, located at approximately 14°W, was recorded for a total period of 10 d, including June 30, the day of the eclipse.
Abstract: FOUR stations were set up in southern and eastern Africa (Table 1) to observe variations of total electron content during the eclipse of the Sun on June 30, 1973. Each station was equipped with a conventional Faraday rotation recording system consisting of a receiver and a mechanically rotating aerial. We recorded the amplitude fading of the 137 MHz signals from the geostationary satellite, Intelsat IIF3, located at approximately 14°W. The four stations were operating for a total period of 10 d, including June 30, the day of the eclipse.
TL;DR: A 200 km long reversed seismic refraction line shot over Porcupine Ridge, a shoal area in the northeast Atlantic jutting out from the continental margin off Ireland, shows that the ridge has a crustal thickness of about 28 km.
TL;DR: It is concluded that the contracture-induction effect of these insecticides is due to their inhibition of SR Ca2+ uptake, resulting in a massive rise in myoplasmic free Ca2+.
Abstract: Relatively pure mitochondrial-free Sarcoplasmic reticulum (SR) was isolated from crab and cockroach skeletal muscle, and the SR calcium uptake was studied in control and insecticide-treated conditions by incubation in Ca45 media followed by millipore filtration and counting by liquid scintillation methods. All insecticides used (parathion, DDT, γBHC and tri-cresyl phosphate) at 1 mM concentrations caused a slight fall in the intrinsic Ca2+ content of the SR, but this Ca2+ loss was insufficient to explain the contracture induction effect of these agents.
TL;DR: A comparison of the behaviour of envelope membranes during illuminated in vitro incubation of isolated etio-plasts with plastids isolated from tissue given similar illumination pre-treatments, indicates that the early increase in envelope-associated protein is real and requires the participation of the cytoplasm.
Abstract: A quantitative estimation of sodium dodecyl sulphate-extractable plastid envelope polypeptides during greening of Avena sativa L. laminae is described, combined with protein distribution and plastid number studies over the same period.
TL;DR: In this paper, an empirical relationship was established between the Tc of A15 superconductors and the atomic mass of the B element, which indicated that log Tc is a linear function of log MB and that high Tc values can be predicted if MB is small.
Abstract: A NEW, empirical relationship1, which links the Tc of A15 superconductors—based on the A3B stoichiometric ratio—with the atomic mass, MB, of the B element, indicated that log Tc is a linear function of log MB and that high Tc values can be predicted if MB is small. A B element is from group IVB (Si, Ge and Sn) and an A element is from group VA (V, Nb and Ta).
TL;DR: A model for the working day of the community nurse is proposed, which takes into account the attachment of the nurse to the patients registered with assigned general practices and the effect that this will have on her travelling time, visiting time and administrative duties.
Abstract: A model for the working day of the community nurse is proposed This takes into account the attachment of the nurse to the patients registered with assigned general practices and the effect that this will have on her travelling time, visiting time and administrative duties It also leads to a method of dividing the country into nursing team regions, assessing the level of nursing service thereby provided
TL;DR: Infra-red, nuclear magnetic resonance and mass spectral analysis after final purification by preparative gas-liquid chromatography showed conclusively that this substance was identical to all-trans-farnesol.
Abstract: Lipid extracts from Sorghum sudanese Stapf (cv Piper) that had been subjected to different degrees of water stress contained increasing amounts of a sesquiterpenoid, other than abscisic acid, as the amount of stress increased and subsequent bioassay showed that this substance was capable of inducing stomatal closure. Infra-red, nuclear magnetic resonance and mass spectral analysis after final purification by preparative gas-liquid chromatography showed conclusively that this substance was identical to all-trans-farnesol. Various derivatives, homologues and isoprenologues of all-trans-farnesol were tested for their ability to close stomata. Only trans-nerolidol approached all-trans-farnesol in activity when applied to isolated epidermis of Commelina communis L. Stomatal closure was induced slightly faster and more completely in the presence of all-trans-farnesol than in the presence of ABA at a similar molar concentration.
TL;DR: In this paper, the in situ isomerization and Diels-Alder reaction with 2-acetoxyacrylonitrile, of 2,5-dihydroanisole, leads to the adducts which may be used as starting point for the synthesis of a number of bicyclo [2,2, 2] octenones, bicyclo[3, 2,1], octenone and bicyclo nonenones.
TL;DR: Ten analogues of abscisic acid have been tested for their activity in assays based on the induction of stomatal closing on isolated epidermis of Commelina communis L., and the inhibition of opening on intact leaves of Xanthium strumarium L.
Abstract: Ten analogues of abscisic acid (ABA) have been tested for their activity in assays based on the induction of stomatal closing on isolated epidermis of Commelina communis L., and the inhibition of opening on intact leaves of Xanthium strumarium L. Three of the analogues showed activity comparable to that of ABA on the stomata of Commelina. The same analogues also showed similar activity and persistence as ABA when applied to the leaf surfaces of Xanthium. Molecular requirements for activity on stomata agree closely with those for activity in the Avena coleoptile assay. The possible value of the analogues as antitranspirants is considered.
TL;DR: In this paper, the electroforming and potential distribution of thin film triodes with both Ag and Au electrodes have been studied, in qualitative agreement with the observations of Hickmott, but no evidence was found to confirm the existence of a narrow high field region close to the cathode, as previously postulated.