Showing papers by "University of Bath published in 1975"
01 Mar 1975
TL;DR: The authors used an applied approach with an emphasis on the understanding of concepts and exposition by means of examples, and sufficient theoretical information is provided to enable applications of regression analysis to be carried out.
Abstract: This text uses an applied approach, with an emphasis on the understanding of concepts and exposition by means of examples. Sufficient theoretical information is provided to enable applications of regression analysis to be carried out. Case studies are used to illustrate many of the statistical methods. There is coverage of composite designs for response surface studies and an introduction to the use of computer-generated optimal designs. The Holm procedure is featured, as well as the analysis of means of identifying important effects. This edition includes an expanded use of graphics: scatter plot matrices, three-dimensional rotating plots, paired comparison plots, three-dimensional response surface and contour plots, and conditional effects plots. An accompanying Student Solutions Manual works out problems in the text.
1,998 citations
TL;DR: In this article, the general interaction energy between an applied stress and a misfitting inhomogeneity is presented and used to deduce the accurate elastic interaction between edge dislocations and point defects in a body subjected to uniaxial tension.
Abstract: The general interaction energy between an applied stress and a misfitting inhomogeneity is presented and used to deduce the accurate elastic interaction between edge dislocations and point defects in a body subjected to uniaxial tension. It is shown that the external stress does, as conjectured by Heald and Speight (1974), cause a preferential drift of interstitials and vacancies to dislocations with particular orientations to the external stress axis. Moreover, for a physically plausible range of the inhomogeneity representation of the point defects the particular preferences found are consistent with those necessary to validate the mechanism of irradiation creep proposed by Heald and Speight.
154 citations
TL;DR: The data indicate that some individuals start feeding in the winter while others do not commence parasitism until the late spring and that this species does not always migrate downstream to saline conditions immediately after metamorphosis.
Abstract: Samples of larvae, metamorphosing and adult representatives of anadromous Petromyzon marinus were collected from rivers in New Brunswick to provide data on aspects of its life cycle. The proportional length of the prebranchial, branchial, trunk and tail regions changed throughout larval life, with the third of these lengths being greater than in Lampetra species, a feature probably related both to the higher number of trunk myomeres and to the greater number of oocytes found in the Sea lamprey. Length-frequency curves for ammocoetes indicate that in general the duration of larval life is from six to eight years. Metamorphosis is initiated in mid-July and has probably been completed by November, paralleling the situation in the landlocked Sea lamprey. Small adults of variable size (167–351 mm) attack Alewives (Pomolobus pseudoharengus) and Atlantic salmon (Salmo salar) in the St. John River at points up to 120 km from the estuary. The data indicate that some individuals start feeding in the winter while others do not commence parasitism until the late spring and that this species does not always migrate downstream to saline conditions immediately after metamorphosis. In a sample of 285 nearly mature upstream migrants caught at the Mactaquac Dam on the St. John River, the ratio of females: males was 1: 1.18. No significant difference was found between the mean length, weight and number of trunk myomeres of the two sexes with respective values of 72.9 cm, 892.1 g and 70.1 being recorded for the females and 72.2 cm, 872.6 g and 69.6 for males. The gonadosomic ratio in males was 1.6 and 14.7 in females. The mean number of eggs per female was 210,228 with a range of 151,836 to 304,832. Spawning takes place in late June/early July when the animals show a sexual dimorphism in body proportions and undergo a reduction in total length. The post-larval phase of the life cycle is considered to last for three or four years, one or two years longer than that recorded for the landlocked form.
109 citations
TL;DR: A variety of different prescriptions have been advanced for the "plotting positions": that is, for the set of values at which the ordered observations in a sample should be plotted as discussed by the authors.
Abstract: SUMMARY Graphical methods of assessing the validity of a probability model, and of estimating location and scale parameters, have been widely applied over many years. A variety of different prescriptions have been advanced for the "plotting positions": that is, for the set of values at which the ordered observations in a sample should be plotted. The more formal proposals vary with the form of the probability model and reflect the function of the enquiry: whether it is predominantly one of model validation or parameter estimation. A closer tie-up of the estimation problem with known properties of order statistics estimators produces an economic recovery of earlier results on probability plotting estimators, some new results in this area, and some general observations on biased order statistics estimators with minimum mean square error.
100 citations
TL;DR: The result of applying the Rademacher-Walsh transform domain classification to Boolean functions of up to fourth order indicates that threshold functions play an important part in the composition of Boolean functions.
Abstract: Five operations are defined in the Rademacher-Walsh transform domain. It is shown that these operations allow Boolean functions to be classified in a very concise way. The result of applying this classification to Boolean functions of up to fourth order indicates that threshold functions play an important part in the composition of Boolean functions. A synthesis method is developed for the synthesis of any Boolean function using, as a basic element, an "optimized universal threshold logic gate." This gate overcomes the analog threshold tolerancing problems encountered in other threshold gate designs and is readily fabricated in an integrated circuit form. The use of this gate in logic design is expected to provide a considerable cost-saving over conventional methods.
90 citations
TL;DR: In this paper, a review of the application of band theory as a basis for understanding catalysis by oxide semiconductors has been presented, highlighting the limitations of the theory itself, the complexity of crystal imperfections in oxides and the extreme versatility of oxide surfaces to form with any given molecule a variety of chemisorbed species.
81 citations
TL;DR: In this article, a model of multibrand purchasing behavior is developed for the independent case and the results help to justify some assumptions which have been made by various authors in the construction of models of buyer behavior.
Abstract: This article is concerned with stochastic models of consumer purchasing behavior for household purchases of frequently bought nondurable consumer goods, such as foods and toiletries. A model of multibrand purchasing behavior is developed for the "independent" case and the results help to justify some assumptions which have been made by various authors in the construction of models of buyer behavior. The implications for a general model of multibrand buying behavior are then considered.
80 citations
01 Mar 1975
TL;DR: In this paper, a real symmetric n × n matrices having orthogonal reductions are considered and the latent vectors of A, B are ordered with respect to respectively and the multiplicities of the roots and in order of occurrence are respectively and, so that the sets of latent roots are each in descending order.
Abstract: Let A, B be real symmetric n × n matrices having orthogonal reductionswhere ΛA = diag (λ1(A), …, λn(A)) and ΛB = diag (λ1(B), …, λn(B)) and the sets of latent roots are each in descending order. (Thus we may say that the latent vectors of A, B are ordered with respect to respectively.) Let the multiplicities of the roots and in order of occurrence be respectively and , so that
71 citations
TL;DR: It is inferred that the distribution in the uterus of the cells which secrete the sites on which calcification is initiated determine ultimately the porosity of the eggshell, implying that evolutionary pressures operate primarily upon these cells rather than on crystallisation.
Abstract: Pores and mammillae per unit area of the eggshells of 34 avian species were counted. The number of pores/cm2 varied from about 45 for the King penguin (Aptenodytes patagonia) to 306 for the Japanese quail (Coturnix coturnix). Throughout this range there was a positive linear correlation (r=0.92) between the number of pores and the number of mammillae per unit area of shell.
Scanning electron micrographs of the inner surface of eggshells scoured with NaOH suggested that the above relationship may result from the packing of the calcite columns, which is controlled by the density of the mammillary seeding sites laid down upon the outer shell membrane. Thus it is inferred that the distribution in the uterus of the cells which secrete the sites on which calcification is initiated determine ultimately the porosity of the eggshell. Such a concept implies that evolutionary pressures operate primarily upon these cells rather than on crystallisation, a process over which a bird may have no control.
58 citations
TL;DR: During 1972 the downstream movement of anadromous artic char from two rivers flowing into Cumberland Sound, Baffin Island, began during the middle of May and was completed within 2 weeks, with the result that the average maximum distance travelled from the natal river was 40–50 km.
Abstract: During 1972 the downstream movement of anadromous artic char, Salvelinus alpinus L., from two rivers flowing into Cumberland Sound, Baffin Island, began during the middle of May and was completed within 2 weeks. This movement took place during both the day and night. Upon reaching saltwater, many char older than 9 years (longer than 20 cm) began to migrate along the shore of the Sound at a rate of 0–6–0-9 km/day with the result that the average maximum distance travelled from the natal river was 40–50 km. Char 6–9 years old, 10–20 cm in length, remained much closer to the rivers while those younger than 5 years never entered saltwater. During the period of saltwater residence, the fish frequently moved into the intertidal zone and freshwater. Maturing fish of both sexes were occasionally found in saltwater. The upstream migration to the lakes began during the second week of August and was completed within 5–6 weeks. Females tended to ascend the rivers before males, although fish of all different size and age migrated upstream simultaneously. Migration occurred during both the day and night. The maximum distance anadromous char moved from saltwater was 40 km. The char were found only in freshwater between May and September and were normally located near the bottom of lakes at a depth of 15–40 m. During this period, large scale movements were probably very limited. Average annual mortality was estimated at 16.0% per year with the highest rates (25–30%) occurring at ages 10 and 15–17 years. Many fish probably died of old age but physical deterioration during and after spawning was also an important cause of death.
44 citations
TL;DR: In this paper, a method involving an acyl anion equivalent for the preparation of deoxybenzoins that are inaccessible by the more usual methods is described, involving acyl acyclic anions.
TL;DR: The enzyme was inhibited in vitro by the non-steroidal anti-inflammatory drugs flurbiprofen, indomethacin and aspirin in the same rank order of potency as prostaglandin synthetase from other tissues.
TL;DR: An investigation has been made of the resistance time and upper lethal temperature of ammocoetes of four species of lampreys provided with a substrate into which they could readily burrow, with the resistanceTime increasing exponentially with decreasing experimental temperature.
Abstract: An investigation has been made of the resistance time and upper lethal temperature of ammocoetes of four species of lampreys provided with a substrate into which they could readily burrow. In general, ammocoetes burrowed after transfer from the acclimation to the experimental temperature baths and later came out of the substrate only in lethal temperatures. A relationship was observed between the resistance time and the time taken to emerge, with the resistance time increasing exponentially with decreasing experimental temperature. In Ichthyomyzon fossor, landlocked Petromyzon marinus, Lampetra (Lethenteron) Lamottenii and in Lampetra (Lampetra) planeri from two different times of the year, the incipient lethal levels over a two week experimental period for larvae acclimated to 15° G were respectively 30.5, 30, 29.5, 28.5 and 28° C. Values for P. marinus acclimated to 5 and 25° C were respectively 29.5 and 31° C, whereas in L. planeri they were 28 and 29° C in April/May and 27 and 29° C in July/August. Extrapolation of the results for the three acclimation temperatures yielded ultimate incipient lethal levels of 31.4° G in P. marinus and 29.2 and 29.4° C for L. planeri examined in the spring and summer respectively.
TL;DR: The origin of the milk-fat-globule membrane is discussed with reference to the intrinsic nature of the associated xanthine oxidase activity and the effect of membrane association on the catalytic properties of the enzyme could be mimicked by low pH or by the presence in the assay mixture of certain concentrations of 2-methyl-propan-2-ol.
Abstract: 1. Xanthine oxidase (EC 1.2.3.2) was found to represent more than 8% of the intrinsic protein of the bovine milk-fat-globule membranes. 2. Less than 25% of the xanthine oxidase activity of the fat-globule membrane was solubilized with 0.1 M-sodium pyrophosphate buffer or 2M-NaCl. Of the particulate activity remaining 56% was solubilized with Triton X-100. 3. The xanthine oxidase activity solubilized with buffer, 2M-NaCl or Triton X-100 was not liberated as the free enzyme. Only tryptic digestion was found to release the free enzyme from the fat-globule membrane. Tryptic digestion also liberated free xanthine oxidase from those fractions solubilized by buffer or NaCl, but not from those fractions solubilized with Triton X-100 or by sonication. 4. The effect of membrane association on the catalytic properties of the enzyme could be mimicked by low pH or by the presence in the assay mixture of certain concentrations of 2-methyl-propan-2-ol, but not 1,4-dioxan, suggesting that hydrogen-bonding rather than low dielectric constant may be involved. 5. The origin of the milk-fat-globule membrane is discussed with reference to the intrinsic nature of the associated xanthine oxidase activity.
TL;DR: Although no character can be used to separate with certainty the larvae of Lampetra fluviatilis and Lampetras planeri, significant differences were found between the mean number of trunk myomeres in the two species.
Abstract: Several taxonomic characters, including the number of trunk myomeres, proportional body measurements and patterns of external and internal pigmentation, have been investigated in populations of ammocoetes belonging to the three species of lampreys found in British rivers. Petromyzon marinus can be readily distinguished by the pigmentary pattern in the tail and on the oral hood, and by the much higher number of trunk myomeres. Although no character can be used to separate with certainty the larvae of Lampetra fluviatilis and Lampetra planeri, significant differences were found between the mean number of trunk myomeres in the two species. Moreover, the values for ammocoetes were virtually identical to those of the respective post-larval stages, at which phase in the life cycle the two Lampetra species are clearly distinguishable. The incidence of pigmentation on the tongue precursor was much higher in larval populations of L. fluviatilis than in those of L. planeri and there was also a difference in the rate of change in the relative length of the trunk and tail. Where comparisons can be made, the results in this paper are in agreement with those of most other European and North American workers. The data differ markedly, however, from that contained in the only other previous detailed systematic study on British larval lampreys, which was subsequently used as the basis for taxonomic keys.
TL;DR: In this article, an inequality for the trace of the product of two symmetric matrices can be used to simplify the proofs of a number of results in multivariate analysis, such as estimating the parameters of a multivariate normal population and estimating a system of linear functional relationships between the mean vectors of k normal populations with the same dispersion matrix.
Abstract: An inequality for the trace of the product of two symmetric matrices can be used to simplify the proofs of a number of results in multivariate analysis. This is illustrated on two problems: estimating the parameters of a multivariate normal population, and estimating a system of linear functional relationships between the mean vectors of k multivariate normal populations with the same dispersion matrix. A new result is proved for the corresponding structural relationship problem.
TL;DR: The problem of finding the stress field induced in the neighbourhood of two spherical gas bubbles or voids in an anisotropic matrix is formulated in terms of an integral equation for the transformation stress in equivalent homogeneous inclusions as discussed by the authors.
Abstract: The problem of finding the stress field induced in the neighbourhood of two spherical gas bubbles or voids in an anisotropic matrix is formulated in terms of an integral equation for the “transformation stress” in equivalent homogeneous inclusions. An iterative method of solution is outlined, involving the solution of a class of problems for a single spherical inclusion perturbing a polynomial field of stress. Explicit solutions are obtained for polynomials up to second degree. Estimates of the energy of interaction between gas bubbles in α-U and between voids in Mo are deduced as examples, and the results are discussed in relation to earlier calculations and to observations.
TL;DR: It was found that the specific radioactivity of the phosphatidyl inositol of the synaptic vesicle fraction showed a reduction of 60%.
Abstract: — The intraventricular injection of 40 μCi of 32Pi (carrier free) into adult rats resulted in maximum incorporation of 32Pi into the phosphatidyl inositol of the whole cortex after 20 h. A further intraventricular injection of 2 nmol carbamylcholine plus 0.02 nmol eserine resulted in a 23% decrease in the specific activity of phosphatidyl inositol after 20 min. The specific radioactivities of phosphatidyl choline, phosphatidyl ethanolarmine and phosphatidyl serine were not changed. Cerebral cortex from rats treated in this way was subjected to an extensive subcellular fractionation. It was found that the specific radioactivity of the phosphatidyl inositol of the synaptic vesicle fraction showed a reduction of 60%. No other fractions showed effects of this magnitude.
28 Oct 1975
TL;DR: In this paper, a detailed analysis of core V19-301 (south of Cape Verde Islands) has been performed for size distribution of quartz grains, mineralogy, color and organic carbon, and G. menardii foraminifera and carbonate.
Abstract: Core V19-301 (south of Cape Verde Islands) has been analysed in detail for (i) size distribution of quartz grains, (ii) mineralogy, (iii) colour and organic carbon (iv) G. menardii foraminifera, and (v) total foraminifera and carbonate. These results are compared with those previously obtained on core V23-100 (north of Cape Verde Islands). It is believed that the carbonate variations can be used to establish simultaneity between the cores, and thus the following climatic data emerge: ( a ) During glacial stages the trade winds were more vigorous than normal for the region north of the Cape Verdes; but the wintertime Harmattan was weaker than normal for the region south of the Cape Verdes. ( b ) The land to the north of Dakar remained desert, and was especially arid during glacials, whereas to the south of Dakar conditions oscillated between desert during interglacials, and savannah during glacials, ( c ) These wind and rainfall oscillations were more rapid and less excursive at around 0.7 Ma than they were in later glacial cycles.
TL;DR: This chapter presents an overview of growth and handling of yeasts, and details are provided for isolation and maintenance ofYeasts.
Abstract: Publisher Summary This chapter presents an overview of growth and handling of yeasts. Yeasts are fungi that exist predominantly in the single-celled state. There are several genera of fungi that, although, contain species able to grow in the yeast state, are not considered true yeasts simply because they do not exist predominantly as single cells. Fungi that are almost yeasts are commonly encountered in genera such as Blastomyces , Geotrichum , Histoplasma , Paracoccidioides , and Sporotrichum. Because yeasts can grow to produce discrete colonies on solidified media, they can easily be isolated from materials that contain low proportions of other microbes by plating a sample of the material on a rich organic medium such as malt extract-agar or Wickerham's malt extract–yeast extract–glucose–peptone (MYGP) medium. Yeasts must be isolated from materials that contain large proportions of bacteria and/or filamentous fungi, particularly materials that have been sampled from natural environments. In the chapter, details are provided for isolation and maintenance of yeasts. Procedures used in the handling of yeast populations are also described.
TL;DR: In this paper, weekly 24-hour samples have been taken of fish species collected from the screens of the Oldbury-on-Severn Nuclear Power Station in the Middle Severn estuary (U.K.).
Abstract: Over a period of a year, weekly 24‐hour samples have been taken of fish species collected from the screens of the Oldbury‐on‐Severn Nuclear Power Station in the Middle Severn estuary (U.K.). The faunal list consists of 48 species compared with the 44 species recorded in a 3‐year survey (based on the examination of commercial catches) made over 30 yrs earlier. Numbers of fish as well as variety of species increased through the autumn and winter, reflecting in part, a seasonal movement of several gadoid species into the estuary. The Power Station samples contained some species not previously recorded specifically for the Oldbury region often in considerable numbers. A short description of the biological characteristics and seasonal changes in frequency is given for each of the more important estuarine species.
01 May 1975
TL;DR: In this paper, a principle of stationary complementary energy for the finite deformation of elastic materials is discussed, but the complementary energy functional depends only on the components of the nominal stress, and not on the displacement field.
Abstract: In a recent paper Koiter (5) discussed a principle of stationary complementary energy for the finite deformation of elastic materials. The complementary energy functional he uses depends only on the components of the nominal stress, and not on the displacement field. He, incorrectly, attributes the principle to Zubov (14).
TL;DR: The mass spectra of six silver(I) carboxylates, AgO2CR, (R = Me, Et, Prn, Ph, CF3 and (CF2)2CF3) showed these compounds to be dimeric in the vapour phase.
01 Jun 1975
TL;DR: Pores arising in the cone layer merge with a plexus of tubules running just under and parallel to the outer surface of the emu eggshell, causing the shell to be irregular.
Abstract: SUMMARY
Pores arising in the cone layer merge with a plexus of tubules running just under and parallel to the outer surface of the emu eggshell. The outer surface of the shell is irregular due to dark green crystalline material arranged as flat domes. The plexus of tubules vent to the ambient environment via short pores opening in the valleys between these domes.
TL;DR: In this article, the authors present some case studies of quality control practices based on the authors' visits to some manufacturing industries and the statistical methods applied in each quality control programme are emphasized.
Abstract: SUMMARY This paper presents some case studies of quality control practices based on the authors’ visits to some manufacturing industries. The statistical methods applied in each quality control programme are emphasized.
TL;DR: A true phytoplankton succession comprising filamentous chlorophytes, Scenedesmus, Melosira varians Ag.
Abstract: The standing crop of benthic and planktonic algae in the Moruya River, Australia, was, in general, low compared with values given for northern hemisphere rivers. Diatoms always accounted for more than 90% of the algae on the sediments with the most common species being typical of holarctic flora. The relative abundance of each of six predominant taxa was similar at the three sampling localities and did not show marked seasonal variation. However, Gomphonema spp. contributed a relatively greater number in the downstream area whereas Cocconeis placentula Ehr. was comparatively more abundant upstream. The highest standing crop (1.47 × 106 cells/cm2) was found downstream and in the calmest part of the river between January and March, coincident with maximum water temperatures. A true phytoplankton succession comprising filamentous chlorophytes, Scenedesmus, Melosira varians Ag., Dactylococcopsis, Eudorina and Merismopedia was observed at the most downstream site during the spring and summer, with a maximum standing crop of 126.7 × 103 cells/litre being attained in December. The gut of larval lampreys > 100 mm contained large numbers (44,000–525,000 cells) of algae. Scenedesmus and Dactylococcopsis occurred much more frequently in the gut than in either the sediment or water, but the reverse was true for filamentous algae.
TL;DR: A simple, inexpensive method is described for the bio-assay of herbicides using micro-algae growing on agar plates, suitable for bio-detection of herbicide residues, or toxicity studies on soil or aquatic pollutants.
Abstract: A simple, inexpensive method is described for the bio-assay of herbicides using micro-algae growing on agar plates. A result is obtainable in 2 days and the method is suitable for biodetection of herbicide residues, or toxicity studies on soil or aquatic pollutants.
TL;DR: Despite the much shorter post-larval period in Lampetra planeri, the adult haemoglobins replaced those of the ammocoete more rapidly in L. fiuviatilis, a feature that may be correlated with differences in the ecology of the metamorphosing stages of the two species.
Abstract: 1.1. Polyacrylamide gel electrophoresis showed that the haemoglobins of ammocoete and sexually mature adults of the non-parasitic lamprey, Lampetra planeri, exhibited identical mobility to those in comparable stages of the proposed ancestral species, Lampetra flaviatilis.2.2. Five bands were seen in electropherograms from ammocoetes, with only the fastest migrating trace band having the same mobility as that of any of the three components observed in the adult.3.3. Despite the much shorter post-larval period in L. planeri, the adult haemoglobins replaced those of the ammocoete more rapidly in L. fiuviatilis, a feature that may be correlated with differences in the ecology of the metamorphosing stages of the two species.