Showing papers by "Newcastle University published in 1972"

An approach to the probability distribution of cusum run length

Abstract: The classical method of studying a cumulative sum control scheme of the decision interval type has been to regard the scheme as a sequence of sequential tests, to determine the average sample number for these component tests and hence to study the average run length for the scheme. A different approach in which the operation of the scheme is regarded as forming a Markov chain is set out. The transition probability matrix for this chain is obtained and then the properties of this matrix used to determine not only the average run lengths for the scheme, but also moments and percentage points of the run-length distribution and exact probabilities of run length. The method may be used with any discrete distribution and also, as ani accurate approximation, with any continuous distribution for the random variable which is to be controlled. Examples are given for the cases of a Poisson random variable and a normal random variable.

Magnetic Properties of Oxidized (Cation-Deficient) Titanomagnetites (Fe, Ti, _??_)43O4

Abstract: A comprehensive study of the magnetic properties of nonstoichiometric (cation-deficient) titanomagnetites is described. Measurement of the saturation magnetization of synthetic samples provides information about the mechanism by which increasingly nonstoichiometric states evolve. It is concluded that in the spinel structure the inherent availability for oxidation of Fe2+ ions on tetrahedral sites is about 20% of that of Fe2+ ions on octahedral sites. Curie temperature increases with degree of oxidation, showing that the increasing vacancy concentration is offset by the greater number of strongly interacting Fe3+ ions. Comparison of calculated and observed Curie temperatures of highly oxidized compositions indicates that such materials have nonideal u-parameters. Thermomagnetic curves of the oxidized samples are of the “anomalous” type, but none was found having compensation temperatures. Coercivity and anisotropy decrease with decreasing Fe2+ ion concentration. Finally, contours of equal cell edge and Curie temperature are constructed for spinels in the FeO-TiO2-Fe2O3 ternary system. These contours may be useful in the identification of naturally occurring samples, provided they do not contain appreciable amounts of other cations. An extrapolated value of 695°C is found for the Curie temperature of γ-Fe2O3.

New light on the Origin of Birds and Crocodiles

Abstract: Detailed evidence from the skull of Sphenosuchus, and from embryological and other resemblances between birds and crocodiles, suggests that these two groups are much more closely related than has been realized

Hydromagnetic convection in a rapidly rotating fluid layer

Abstract: The linear stability of a rotating, electrically conducting viscous layer, heated from below and cooled from above, and lying in a uniform magnetic field is examined, using the Boussinesq approximation. Several orientations of the magnetic field and rotation axes are considered under a variety of different surface conditions. The analysis is, however, limited to large Taylor numbers, T , and large Hartmann numbers, M . (These are non-dimensional measures of the rotation rate and magnetic field strength, respectively.) Except when field and rotation are both vertical, the most unstable mode at marginal stability has the form of a horizontal roll whose orientation depends in a complex way on the directions and strengths of the field and angular velocity. For example, when the field is horizontal and the rotation is vertical, the roll is directed parallel to the field, provided that the field is sufficiently weak. In this case, the Rayleigh number, R (the non-dimensional measure of the applied temperature contrast) must reach a critical value, R c , which is O ( T 2/5 ) before convection will occur. If, however, the field is sufficiently strong [ T = O ( M 4 )], the roll makes an acute angle with the direction of the field, and R c = O ( T 1/2 ), i.e. the critical Rayleigh number is much smaller than when the magnetic field is absent. Also, in this case the mean applied temperature gradient and the wavelength of the tesselated convection pattern are both independent of viscosity when the layer is marginally stable. Furthermore, the Taylor-Proudman theorem and its extension to the hydromagnetic case are no longer applicable even qualitatively. Over the interior of the layer, however, the Coriolis forces to which the convective motions are subjected are, to leading order, balanced by the Lorentz forces. The results obtained in this paper have a bearing on the possibility of a thermally driven steady hydromagnetic dynamo.

The effect in sheep of physical form on the sites of digestion of a dried lucerne diet. 2. Sites of nitrogen digestion.

Abstract: I . The effect of altering the physical form of a regrowth crop of dried lucerne (Medicago sutivu L. var. Chartuinvilliers) on the sites of organic matter, energy and carbohydrate digestion was studied with sheep fitted with re-entrant cannulas at the proximal duodenum and at the terminal ileum. 2. Chopped, cobbed, and ground and pelleted diets with moduli of fineness of 3.~~2.7 and 1-5 respectively were prcpared from the same high-temperature dried crop and given twice daily to sheep at a level of intake of 910 g dry matter/d. 3. Physical form did not affect the apparent digestibility of the organic matter. On the cobbed and pelleted diets losses of digestible organic matter before the small intestine were significantly lower (P < 0.05; P < 0.001 respectively) and losses in the small intestine were significantly higher ( P < 0 .05) than for the chopped diet. 4. Apparent digestibility of the gross energy of the three physical forms was similar, but the flow of energy into, and digestion within, the small intestine were markedly greater (P < 0.05) for the ground and pelleted diet than for either the chopped or cobbed diet, for which the values did not differ. Energy digestion in the caecum and colon was similar for the three physical forms. 5. Total cellulose and hemicellulose digestibilities were not affected by processing, but the proportion of the digestible cellulose and digestible hemicellulose digested in the fore-stomachs of sheep given the ground and pelleted diet (63 and 55 % respectively) was less than for the chopped diet (85 and 68 yo). The digestibility of the cobbed diet was intermediate. Digestion in the caecum and colon compensated for these differences in digestion of cellulose and hemicellulose in the fore-stomachs. 6. Volatile fatty acid (VFA) concentration in the rumen liquor was lower in sheep given ground, pelleted lucerne than in those on the chopped diet, but the VFA proportions were very similar. The implications of the change in site of energy and carbohydrate digestion with grinding and pelleting are discussed.

Studies in the History of Probability and Statistics. XXIX The discovery of the method of least squares

Abstract: SUMMARY The circumstances in which the discovery of the method of least squares took place and the course of the ensuing controversy are examined in detail with the aid of correspondence. Some conclusions are drawn about the attitudes of the main participants and the nature of historical research in statistics.

The lipid–teichoic acid complex in the cytoplasmic membrane of Streptococcus faecalis N.C.I.B. 8191

Abstract: 1. A lipid–teichoic acid complex was isolated from Streptococcus faecalis N.C.I.B. 8191. The covalent nature of the linkage between teichoic acid and lipid was established. 2. The complex exhibits macromolecular properties in solution, and ultracentrifugation studies show that these are due to micelle formation. 3. From chemical studies it is concluded that the teichoic acid is a poly(glycerol phosphate) in which some of the glycerol hydroxyl groups possess kojibiosyl [2-O-α-d-glucopyranosyl-(1→2)-α-d- glucopyranosyl] substituents, together with d-alanine ester residues. 4. The lipid is 1-kojibiosyl diglyceride, already known as a membrane component of this organism, with probably a phosphatidyl substituent. The phosphatidyl kojibiosyl diglyceride is attached to the teichoic acid through a phosphodiester linkage, and the chain of the teichoic acid contains 28–35 units. 5. Although the complex represents the whole of the membrane teichoic acid in this organism, only about 12% of the membrane glycolipid is associated with teichoic acid. 6. Two phosphatidyl glycolipids, closely resembling that bearing the teichoic acid, were isolated from the lipids of the organism and were partly characterized.

Electromagnetic Core-Mantle Coupling

Abstract: The time-scale of the variation in the length of the day is comparable to, or shorter than, the electromagnetic decay time, τη, of the mantle. This suggests that an electromagnetic theory for the origin of these fluctuations should not only depend on the electromechanical coupling time, τI, introduced by ROCHESTER (1960), but also on τη. It is shown that, when τI is small compared with τη, the fluctuation time for perturbations in the angular velocity of the mantle is of order τc=τI2/3τη1/3, and not τη. The possibility that τI is not large compared with τη for the case of the Earth is considered. Also, by means of a simple shellular model of the core, the role of Alfven waves in modifying the coupling of core to mantle is discussed. The relationship of this theory with that of BRAGINSKII (1970) is briefly noted. A new account is given of mantle induction which, although only valid at small magnetic Reynolds numbers (based on the conductivity of the mantle), is sufficiently general to permit the coupling of the mantle to an arbitrary slow motion on the core surface to be treated.

The mechanism of wall synthesis in bacteria. The organization of enzymes and isoprenoid phosphates in the membrane

Abstract: 1. The synthesis of peptidoglycan and teichoic acids by cell-free preparations from Bacillus licheniformis A.T.C.C. 9945 and Bacillus subtilis N.C.T.C. 3610 has been studied under a variety of conditions. 2. It was shown that poly(glycerol phosphate) is synthesized through a lipid intermediate, and it is concluded from this and other work that all major bacterial wall polymers are formed in a similar manner through such intermediates. 3. Close interrelation between the synthesis of peptidoglycan and teichoic acids was demonstrated, and inhibition studies confirm that the polyprenol phosphate molecules participating in the synthesis of peptidoglycan are shared with the systems that synthesize teichoic acids. 4. Nucleotides for the synthesis of one polymer are inhibitory towards synthesis of the other, and these effects can be enhanced or diminished by preincubation of the enzyme system with appropriate nucleotide precursors. 5. It is concluded that the return of undecaprenol phosphate to a common pool occurs only after the completion of polymer chains, and not after each cycle in the attachment of individual repeating units. This and other observations support a model for bacterial wall synthesis in which the multi-enzyme systems for each polymer are closely aligned in the membrane, with a molecule of undecaprenol phosphate located between them in a manner that enables it to be shared. The general mechanisms of wall synthesis and its control are discussed.

The effect in sheep of physical form and stage of growth on the sites of digestion of a dried grass. 1. Sites of digestion of organic matter, energy and carbohydrate.

Abstract: I . The efyect of grinding and pelleting artificially dried S 24 perennial rye-grass (LoZium perenne L.) cut at two stages of maturity on sites of digestion of organic matter, energy and carbohydratc were studied in sheep with re-entrant intestinal cannulas fitted at the proximal duodenum and terminal ileum. Chopped and pelleted grasses at both stages of maturity were each given at 900 g dry matter/zq h to each of five sheep; the two forms of the early-cut grass were also given at 1400 g dry msltter/zq h each to four of the fivc shccp. 2. With the carly-cut grass, grinding and pelleting caused a depression in digestibility of organic matter (low level, P < 0 . 0 5 ; high level, P < woor), lo\\vered the proportion of the digested organic matter disappearing before the small intestine (low level only, P < 0.05) and significantly increased that disappearing in the caccum and colon (low level, P 4 0.05 ; high level, P < OYJOI). Increase in stagc of maturity significantly depressed digestibility of organic matter ( P < 0001) with both forms of grass and, with the chopped form, significantly increased the proportion of digestible organic matter disappearing in the caecum and colon (P < 0.01). Increase in level of feeding of the pelleted, early-cut grass significantly lowered organic matter digestibility ( P < O . O ~ ) , reduced the proportion of digestible organic matter disappearing in the small intestine ( P 4 005) and increased that occurring in the caecum and colon ( P < 0.05). 3. With the early-cut grass, grinding and pelleting caused 3 depression in digestibility of gross energy only at the higher level of intake ( P < O O I ) , and reduced the proportion of apparently digestible energy disappearing before the small intestine (IOW level, P < 0.001 ; high level, P < 0.05). Only with the chopped form did stagc of maturity affect sites of energy digestion; with the more mature grass disappearance of energy in the reticulo-rumen declined (P < 0.01) and that in the caecum and colon increascd (P < 0301). The effects of level of feeding were similar to those observed for organic matter. 4. With the early-cut grass, and at both levels of intake, digcstibilities of cellulose and hemicellulose were depressed by grinding and pelleting (P < O.OOI), as were the proportions of digestible cellulose and hemicellulose disappearing before the small intestinc (P < 0.001). Thc proportions of these digestible fractions disappearing in the caecum and colon werc significantly increased (P < 0.001). Increase in stage of maturity depresscd cellulose digcstibility (P i 0.001) of the chopped but not pelletcd grass and depressed hemicellulose digestibility of both forms (P < 0001). The effects of increase in maturity at harvest on sites of digestion depended upon the form of the grass, With the chopped form, as stage of maturity increased, the proportion of digestible hemiccllulose disappearing in the reticulo-rumen fell ( P < 0.01) and that, and the proportion of digestible cellulose, disappearing in the caecum and colon increased ( P < 0'01 and P < 0.05 respectively); with the pelleted form, the proportions of digcstible cellulose and digestible hemicellulose disappearing in the reticula-rumen increased ( P < 0.001 and P < OOI respectivcly) whereasthosedisappearingin the caecum and colon declined ( P < 0.01). With the pelleted, early-cut grass increase in intake resulted in a depression in cellulose and hemicellulose digestion ( P < 0 0 5 and P < 0.001 respectidy) and increased proportional losses of digestible cellulose and digestible hcmiccllulose in the caecum and colon ( P 4 0'01 and P < 0.05 respectively).

The structure and formation of growth-ridges in scleractinian coral skeletons

Abstract: The external surface of the epitheca in modern and fossil corals is marked by tiny ridges lying parallel to the epithecal rim. These ridges have been assumed to be daily growth increments, and have been linked with supposed lunar and seasonal events recorded in the skeleton, to compute aspects of the history of the Earth9s rotation. This communication presents structural and experimental evidence to show that the growth-ridges in the epithecae of modern hermatypic scleractinian corals, particularly Manicina areolata (Linnaeus), are formed as a result of daily changes in the shape of the tissues secreting the epithecae. The changes in shape of the tissues are an integral part of the mechanism by which the body wall of these corals is adjusted in position to accommodate for epithecal growth. This adjustment takes place in concert with a daily cycle of expansion and contraction of the animals. Because the epitheca is formed at the perimeter of the skeleton-secreting layer, its growth involves certain fundamental requirements. The presence of growth-ridges in all coral epithecae suggests that all corals meet, or met, these requirements with a similar mechanism to that which operates in the hermatypic species studied. However, the mechanism is not necessarily linked to a daily cycle of expansion and contraction.

The effect in sheep of physical form and stage of growth on the sites of digestion of a dried grass: 2. * Sites of nitrogen digestion

Abstract: I . The effect of grinding and pelleting S 24 perennial rye-grass (Lolium perenne L.), harvested at two stages of maturity and artificially dried, on the sites of digestion of nitrogenous constituents was studied with sheep equipped with a fistula into the rumen and re-entrant cannulas at the proximal duodenum and terminal ileum. Chopped and pelleted grasses at both stages of maturitywere each givcn at goo g dry matter ( D M ) / z ~ h to each of five shcep; the two forms of the early-cut grass were also given each to four of the five sheep at 1400 g D M / Z ~ h. 2. The pelleting process significantly depressed apparent digestibility of total nitrogen in both grasses (P < 0.05). For the early-cut grass neither physical form nor level of feeding had any significant cffect on N retention; for the medium-cut grass N retention was significantly higher (P < 0.05) when thc pelletcd form was given. N retention was significantly lower on the medium-cut grass (P < 0.05) than on the early-cut grass. 3. For individual amino acids the greatest relative increases (intake = 100) at the proximal duodenum were found for mcthionine and cysteine/cystine ( P < 0.001) on all six diets, together with tryptophan (P at least < 0.01) and lysine (P at least < 0.05) on five of the diets, and including histidine on the early-cut diets ( P at least < 0.01) . At the low level of feeding, incrcase in stage of growth at cutting significantly dcpressed the relative amounts of phenylalanine, lysine, serine ( P < 0.05), histidine, aspartic acid and tyrosine ( P < 0.01) entering the small intestine, and increased those of tryptophan ( P < 0.05). Pelleting of the early-cut grass significantly increased the amounts of methionine entering the small intestine compared with feeding it chopped (P

Piety and impiety in thirteenth-century italy

Abstract: Everyone is familiar with the notion of an ‘Age of Faith’. It is the idea that, at some time in the past, everyone believed what religious authority told them to believe. In this paper I propose to test the truth of this idea, in one period, and one region. I have chosen thirteenth-century Italy. The Middle Ages stand, par excellence, as the Age of Faith; and the thirteenth century, late enough not to starve us of evidence, was still early enough to be safely medieval. Italy, too, chooses itself: its documents, and its debates, yield the historian a clearer picture than he would get elsewhere. Whether Italy was typical of latin Christendom is a question that would call, not for another paper, but for another conference. But hints of her position will appear in the course of our enquiry. Some sources singled her out, some did not – giving an assurance, between them, that any difference between Italy and the rest was a difference between shades of grey. Italy, then, in the thirteenth century, is our field; and we shall be enquiring in it not, now, about kinds of belief, but about degrees of it. How far were our predecessors, in the time and place chosen, in the modern sense ‘religious’?

The working of copper-arsenic alloys in the Early Bronze Age and the effect on the determination of provenance.

Abstract: The earliest copper alloy of the British Bronze Age is arsenical copper, a material relatively short-lived when compared with the succeeding tin bronze but of no little importance when tracing the stages and progress of prehistoric metal working. Like tin, arsenic functions as a mild deoxidant and confers the useful property of work-hardening upon the metal. Copper-arsenic alloys need to be strengthened by cold working, and it was probably this requirement as much as any other that would have led to their eventual disuse and replacement by cast tin bronzes. The normal source of arsenic for such alloys is generally agreed as a constituent of the copper ore actually smelted, usually the grey tetrahedrite tennantite mineral (Coghlan and Case, 1957; Tylecote, 1962), although other suggestions have been made (Charles, 1967).

The propagation of a weak nonlinear wave

Abstract: We consider the propagation of a weak nonlinear wave whose energy is concentrated in a narrow band of wavenumbers in a fluid which is both dispersive and dissipative. We use the small amplitude equations of Whitham's theory of slowly varying wave trains, modified slightly to include dissipation, to show that the modulation of the wave may be described by a nonlinear Schrodinger equation. For long waves which are purely dispersive we obtain the Kortewegde Vries equation, and for long waves which are dissipative we obtain Burgers’ equation by suitable transformations of the nonlinear Schrodinger equation. We mention the problem of Stokes waves in deep water and comment briefly upon invariant far-field theory.

Some numerical solutions of a variable-coefficient Korteweg-de Vries equation (with applications to solitary wave development on a shelf)

Abstract: Some numerical solutions of a variable-coefficient Korteweg-de Vries equation are presented. This particular equation was derived by the author recently (Johnson 1972) in an attempt to describe the development of a single solitary wave moving onto a shelf. Soliton production on the shelf was predicted and this is confirmed here. Results for two and three solitons are reproduced and two intermediate shelf depths are also considered. In these latter two cases both solitons and an oscillatory wave occur. One of the profiles corresponds to the integrations performed by Madsen & Mei (1969) and a comparison is made.

Drifting Through the Year

Abstract: Many of the difficulties associated with attempts to apply plate tectonics to geophysical phenomena are a result of applying the basic tenets in too simple a manner.

The maturation and breeding biology of Harmothoë imbricata (Polychaeta: Polynoidae)

Abstract: The embryos of Harmothoe imbricata (L.) are protected during their early development as a mass under the scales of the female parent. Eggs are shed into the space under the scales through nephridial papillae which elongate and turn dorsally as the female matures. The mass is held together by an adhesive layer surrounding each egg. Maturation begins in September and breeding occurs during March and April, when each female spawns twice in succession. Males contain mature sperm throughout the breeding season and shed only a small proportion at each spawning. As the polychaetes mature, pairs are formed with the male resting on the dorsal surface of the female. When the female spawns, the male sheds sperm over the egg mass and the two animals then separate. The sperm has a long acrosome to penetrate the adhesive layer around the egg. Embryo-protecting species in other groups of polychaeces show parallel specialization in sperm structure and in breeding behaviour. A chronology has been established for the development of embryos up to their release from the parent, and this can be used to estimate the spawning date of females with embryo masses collected on the shore. Individuals grow at widely varying rates after settlement on the shore, and no year classes could be detected in the population. All individuals spawn in the first spring after settlement, and at least some survive to spawn again in one or more subsequent springs.

Variation in the duration of mitosis in the crypts of lieberkuhn of the rat; a cytokinetic study using vincristine

Abstract: The variation in the duration of mitosis (tm) with cell position in the small intestinal crypts of the adult rat has been measured by a stathmokinetic technique using vincristine. The value for the whole crypt column was 0.43 hr, or 26 min. At the bottom of the crypt tm was in excess of 1 hr, but rapidly decreased and throughout the greater part of the proliferative compartment was between 0.40 and 0.50 hr. At the top of the proliferative compartment an increase in tm was demonstrated. If the value of 0.43 hr for the whole crypt column is correct, then one argument for postulating the formation of metabolic DNA during differentiation in the small bowel epithelium of the rat becomes invalid. Variations in tm within the crypt have been shown to increase the values of cell velocity obtained from cumulative birth rate diagrams. Finally further evidence has been presented for the existence of a slowly dividing subpopulation of cells at the base of the crypt. These cells may be important in crypt repopulation after damage with phase specific anti-tumour drugs.

Fine-structural observations on the gill filaments of the freshwater crayfish, Astacus Pallipes Lereboullet

Abstract: The gills of the crayfish are described with special reference to the tissues of the branchial filaments. An account is given of a possible pathway of blood flow through the filaments to ensure maximum oxygenation at the epithelial surface. The branchial epithelium consists of a thin, subcuticular layer with an indented apical plasma membrane, and projecting cell bodies. The basal epithelial surface adjacent to the haemolymph possesses the deep membrane infoldings characteristic of resorptive epithelia. Ion and water movement across the epithelium is discussed.