Showing papers by "Trinity College, Dublin published in 1969"

A Pollen Diagram from Mud Lake, Marion County, North-Central Florida

Abstract: Six pollen zones are described from a 1360-cm profile of sediments from a lake in north-central Florida. Zone Ml, at the top, has pollen predominantly of Pinus (pine) with some Quercus (oak) and other broad-leaved trees. It extends from the present back to 5070 ± 150B.P., and it represents a vegetation of sand-pine scrub, as today. Zone M2 has high Quercus percentages with much pollen of herbs, shrubs, and aquatics. It represents a sclerophyllous oak scrub or dry forest; it is dated at 8260 ± 200 B.P. at its base. Beneath zone M2 is a sand layer that marks a major hiatus, for the sediment immediately beneath it is over 35,000 years old. At this time the lake was dry, probably because the water table was lowered as a result of eustatic depression ofsea level during Wisconsin glaciation. Zone M3 below the sand layer resembles zone M2, so it must also reflect a warm-temperate climate, presumably of Sangamon age. Zone M4, with dominantly pine pollen, is also assigned t o the Sangamon. Zone M5 has abundant Quercus, Carya (hickory), and Liquidambar (sweet gum), and zone M6 has predominant Pinus with a trace of Picea (spruce). Both zones include Acer saccharum type (sugar maple), Fagus (beech), Tilia (basswood), and Carpinus type (hornbeam); they represent mesic hardwood forest, tentatively assigned to the time of the Illinoian glaciation.

The purification and properties of cytidine aminohydrolase from sheep liver.

Abstract: Cytidine aminohydrolase was purified about 280-fold with an overall 8% yield from the cytoplasmic fraction of sheep liver cells by the use of protamine sulphate precipitation, salt fractionation using trisodium citrate, acidification and chromatography on DEAE-and CM-celluloses. The enzyme catalyses the deamination of several aminopyrimidine nucleosides. Its pH optimum occurred at 5.0 and it was relatively acid and heat stable. The high sensitivity of the enzyme to compounds known to react with sulphydryl groups and the presence of a substrate-binding group of pKa 9.2 in the enzyme suggests that a sulphydryl group may be important in the catalytic process. dTTP and dUTP were found to inhibit and dCTP to activate the enzyme respectively. The complex type of inhibition produced by dTTP indicates that this aminohydrolase may have a regulatory role similar to that of dCMP aminohydrolase.

Gneisses in the north-western part of County Mayo, Ireland

Abstract: A metamorphosed complex of basic and acid gneisses, which occurs in north-west County Mayo, Ireland, structurally underlies younger Moinian and Dalradian type metasediments. These gneisses are compared directly with the Lewisian ‘inliers’ of the western Highlands of Scotland.

A nucleoside triphosphate-dependent deoxyribonucleic acid-breakdown system in Mycobacterium smegmatis, and the effect of iron limitation on the activity of this system

Abstract: 1 The presence of a nucleoside triphosphate-dependent DNA-breakdown system was demonstrated in extracts of Mycobacterium smegmatis Its activity was increased substantially by iron limitation, apparently after the fall in DNA content that took place under these conditions A maximal activity of about 0·2μmole of deoxyribonucleotide/30min/mg of protein was found in crude extracts 2 After slight purification by streptomycin treatment, the enzyme showed maximal activity with undenatured DNA (Km≃200μg/ml), ATP (Km≃1·2mm) or UTP, CTP and GTP giving lower activity and pyrophosphate giving none, and Mg2+ ions (optimum concn 12mm) The optimum pH was 8·5 3 In the assay system there was proportionality between enzyme concentration and rate of reaction, but the rate fell off with time 4 ATP was broken down in the reaction and monodeoxy-ribonucleotides were among the products, but the presence of some oligodeoxy-ribonucleotides was not excluded and the degree of phosphorylation of the primary products was uncertain

Inhibition of Pacemaker Systems in the Hydroid Tubularia

Abstract: 1. Of the three conducting systems known in the stalk of Tubularia --the slow system (SS), the triggering system (TS), and the distal opener system (DOS)--the SS can be eliminated as being necessarily involved in the pacemaker system inhibition seen during continued stalk stimulation because its threshold is higher than the minimal stimulus strength required for inhibition. The TS can also be eliminated as the inhibitory pathway because (1) separating a polyp from a colony and hence from a source of continued input along the TS does not result in an increase in the spontaneous activity of the polyp above that of appropriate controls, and (2) distal tentacle stimulation which activates the DOS but not the TS is more inhibitory than is stalk stimulation which excites both the TS and the DOS. The inhibitory pathway is apparently the DOS or, less likely, a yet unidentified conducting system in the stalk. 2. Inhibitory stimulation suppresses both single pulses and bursts in the NP pacemaker system and it is likely that the HP pacemaker system is also inhibited. The greater the background level of spontaneous activity the greater is the effectiveness of inhibitory stimulation. The period of inhibition lasts for a few seconds after each stimulus.

The effect of oral ammonium chloride on the urinary excretion of calcium, magnesium and sodium in man

Abstract: The effect of a single oral dose of ammonium chloride on urinary calcium, magnesium and sodium, has been studied

Plato On Truth And Falsity In Names

Abstract: In Cratylus 385 b-c Plato argues that if statements ( ) can be true or false, names ( ), 2 as parts ( ) of statements, are also capable of being true or false. From Aristotle onwards this view has often been challenged, 3 and R. Robinson put the case against it trenchantly when he wrote: 4 This argument is bad; for names have no truth-value, and the reason given for saying that they do is a fallacy of division. No one in the dialogue points out that it is bad. … Nevertheless it is fairly probable that Plato saw or at least felt that it is a bad argument, quite different in quality from those he later produces against the nature-theory.

Costs and Efficiency

Abstract: At the beginning of 1926 an impasse had been reached in the struggle to reduce costs of production in industry. The successes achieved in the winter of 1924–1925, when wages were frozen and productivity rose rapidly, were partly eroded by the renewed rise in wages in the second half of 1925, and by the first unmistakable symptoms of inflation.1 Neither of the two immediate aims of cost reduction — to lower the prices of industrial products and to increase industrial profits — seemed any longer within reach. These developments could not be dismissed merely as temporary mishaps. The ending of the wage-freeze in the spring of 1925 showed that considerable firmness was required if any substantial gap between increases in productivity and increases in earnings was to be maintained. The economic difficulties of the summer and autumn of 1925 showed that the margin of resources available to the central authorities for expansion without inflation was quite small. Rising industrial costs created a financial crisis in such major units as Yugostal and Yuzhmash-trest in the spring of 1926.2 The difficulties were made more acute by longer-term influences which began to be effective at this time.

The construction of sections in areas of highly deformed rocks

Abstract: Summary The construction of sections is essential to the analysis of rock bodies. Qualitative sketch sections and block diagrams help to unravel stratigraphy within complex polyphase structures. They also provide a method of summarizing information. Present methods of constructing quantitative sections, being only applicable to parallel folds, are of limited value. A new method of constructing quantitative sections is described. In this the rate of change of fold shape with depth is measured, rather than assumed as previously. On profile sections of folds, this rate can be described by constructing stratification isogonal lines joining points of constant dip. Their orientation can be used to classify folds. In cylindrical folds, such isogonal lines lie upon stratification isogonal surfaces, the location of which can be found from structural maps, either by graphic construction, or by using a digitizer and an electronic computer. This information is used to construct, on any section plane, stratification isogonal lines which sub-divide the section into dip zones, and provide control for constructing sections to the depth of topographic or structural relief. Applications of the method to recognizing faults and palaeoslopes, and to classifying folds and constructing sections in areas of noncylindrical and polyphase deformation, are described. These methods make fuller use of structural data and provide quantitative descriptions of folds. This could lead to the definition of structural facies and to a better understanding of displacements within the continental crust.

Toxoplasma lymphadenitis. A report of six cases.

Abstract: One probable, and five definite examples of toxoplasma lymphadenitis are presented, and attention is drawn to the histological features by which this infection may be recognised. The importance of distinguishing these appearances from those found in certain forms of Hodgkin’s disease is emphasised. It would appear that acquired, adult toxoplasmosis is not uncommon in Dublin.

“Self-Feeding” Strain of Salmonella typhimurium with a Mutation in the trpB Gene and Nutritional Requirements of trpA Gene Mutants

Abstract: An indole-requiring (Ind−) mutant of Salmonella typhimurium, isolated from a culture of a leaky trpA mutant, was genetically analyzed by P22-mediated transduction. The mutation site giving the Ind− phenotype was shown to be in trpB, the second gene of the trp operon. A second mutation at this site resulted in change of nutritional requirement from indole to anthranilic acid (Anth−). This phenotype is normally associated with mutations in the first trp gene, trpA. However, the Anth− mutant also excreted anthranilic acid and showed “self-feeding” on unsupplemented media. Of two possible explanations for this aberrant phenotype, the first, that the trpB mutations may be in the “unusual” region, was dismissed on genetic evidence and on the biochemical evidence that an active anthranilate synthetase (AS) is produced. The alternative explanation, that the affected enzymatic activity, phosphoribosyl transferase, is unstable in vivo, but its AS component 2 activity is stable, is considered more probable.

On the computation of transition matrix

Abstract: A method is suggested for the evaluation of the transition matrix associated with a linear time-invariant multivariable system and it is shown that this method is faster and more accurate than other numerical methods.

The incidence of lactase deficiency following partial gastrectomy.

Abstract: LACTASE deficiency in a group of 33 post partial gastrectomy subjects was found to be no more common than in 16 normal control subjects. These results are similar to the reported results in the literature for Caucasian subjects and do not support the thesis that post gastrectomy milk intolerance is due to acquired or latent intestinal lactase deficiency in the majority of cases. The reason for the variable results obtained in the literature is discussed.

Reactivity of Serum from Frogs and Other Species with a Herpesvirus Antigen Extracted from a Burkitt Lymphoma Cultured Cell Line

Abstract: Since 1964, when Epstein et al. (1) described the presence of herpesvirus in cultured cells of a biopsy of Burkitt lymphoma, many investigators from various parts of the world have confirmed and extended this observation. To date, cell lines have been successfully grown in culture from at least 125 individuals (2). Of those derived from malignant states, including leukemia and lymphoma, 44 of 105 tested or 42 percent contained a herpesvirus morphologically indistinguishable from that originally described by Epstein. Of those derived from normal persons or those with other diseases, 4 of 19 or 21 percent contained a similar herpesvirus. Despite intensive efforts in several laboratories, this virus has not been identified as a known herpesvirus. The term EBV—Epstein-Barr virus—has been suggested as a name for this unidentified herpesvirus strain.

Shorter Confidence Intervals Using Prior Observations

Abstract: The purpose of this paper is to make the reader aware of the applicability and advantage of a particular mathematical model. The application is typified by an example and the advantage is via confidence intervals; that is, shorter confidence intervals are possible using the model than if one ignores it, providing the applicability is valid. It is also shown that an improved estimate can be obtained through use of the model. Let f(y|μ,σ) be a normal density with mean μ and variance σ2 and let g(μ|λ, β) be a normal density with mean λ and variance β2. A sequence y 1, y 2, …, y n+1 of independent observations from the mixture of f and g can be considered as follows: An unobservable μi is first drawn from g(μ|λ, β) and then yi which can be observed is drawn from f(y|μi, σ). Confidence intervals on μ n+1 are obtained which are based on the observations y 1, …, y n+1 and which are shorter than the standard interval based on y n+1 only for any n. Shorter intervals are obtained for two cases: (i) λ unkno...