Showing papers by "Trinity College, Dublin published in 1981"

The ability to recognize oneself from a video recording of one’s movements without seeing one’s body

Abstract: Certain individuals are very much better than others at recognizing themselves from a recorded point-light display of their movements without being able to see their bodies They are better at recognizing themselves in this way (although they have never seen themselves walking from an external point of view before) than they are at recognizing their friends, whom they see walking every day, and better than their friends are at recognizing them This suggests some sort of kinesthetic-visual cross-modal transfer

A Yang-Mills-Higgs monopole of charge $2$

Abstract: A new static, purely magnetic Yang-Mills-Higgs monopole solution is presented. It is axisymmetric and has a topological charge of 2; the charge is located at a single point.

Magnetic properties of sheet silicates; 2:1:1 layer minerals

Abstract: Magnetization, susceptibility and M6ssbauer spectra are reported for representative chlorite samples with differing iron content. The anisotropy of the susceptibility and magnetization of a clinochlore crystal is explained using the trigonal effective crystal-field model developed earlier for 1:1 and 2:1 layer silicates, with a splitting of the Tzg triplet of 1,120 K. Predominant exchange interactions in the iron-rich samples are ferromagnetic with J= 1.2 K, as for other trioctahedral ferrous minerals. A peak in the sus- ceptibility of thuringite occurs at Tm = 5.5 K, and magnetic hyperfine splitting appears at lower temperatures in the M6ssbauer spectrum. However neutron diffraction reveals no long-range magnetic order in thuringite (or biotite, which behaves similarly). The only magnetic contribution to the diffraction pattern at 1.6 K is increased small angle scattering (q<0.4~ 1). A factor favouring this random ferromagnetic ground state over the planar antiferromag- netic state of greenalite and minnesotaite is the presence of pairs of ferric ions on adjacent sites, in conjunction with magnetic vacancies in the octahedral sheets. Monte Carlo simulations of the magnetic ground state of the sheets illus- trate how long range ferromagnetic order may be destroyed by vortices forming around the Fe 3 +--Fe 3 + pairs. tral in chlorites. Substitution of trivalent ions for Mg in the brucite layers is compensated by replacement of Si by A1 in the tetrahedral sheets of the talc layers (Bailey 1980). The general formula for a trioctahedral chlorite is

A Theoretical Treatment of the Sliding of Glaciers in the Absence of Cavitation

Abstract: A model is proposed for the description of glacier sliding which includes the nonlinearity of the flow law for ice. The model describes coupled flow problems in the basal ice and a thin water film, together with a temperature problem in the underlying bedrock. To determine the sliding law relating basal velocity to basal stress, the sliding theory should be formulated as a boundary layer to the larger-scale bulk ice flow. Dimensional analysis indicates that the regelative component of ice velocity may be neglected, provided roughness is absent at the smallest wavelengths and then the ice flow effectively uncouples from the other problems. In this case, with the crucial ( but unrealistic) assumption that the flow law for temperate ice is independent of the moisture content, there exist complementary variational principles that describe the functional form of the sliding law and give bounds on the magnitude of the 9roughness9 coefficient. These principles are valid for nonlinear stress-strain rate relations and for non-vanishing bedrock corrugation, and indicate how the basal velocity is determined by two parameters that together describe the degree of roughness of the bed. Specific estimates are then given. Finally, the main weakness in the model as a predictor of quantitatively accurate results is pointed out: that is, that the variation of moisture within the basal layer, and the resultant effect on the flow law, are neglected. A valid description of this phenomenon does not yet appear to be available.

Acute Wernickes encephalopathy precipitated by glucose loading.

Abstract: Four cases of acute Wernickes Encephalopathy in non-alcoholic, malnourished patients are described. In each case the administration of a glucose load precipitated a neurological crisis which was rapidly reversed by the administration of intravenous Thiamine. It is suggested that prophylactic Thiamine treatment therapy should be considered in the management of all malnourished patients.

Genetic analysis of K88-mediated adhesion of enterotoxigenic Escherichia coli

Abstract: Four cistrons (adh) involved in the expression of the K88 adhesion system have been identified and mapped. Three of these (adh A, adh B and adh C) are located in a single operon(I) whereas the fourth (adh D) is expressed from a separate promoter (operon II). The polypeptides encoded by these cistrons have been identified and their role in the formation and regulation of K88 fimbriae (pili) is discussed.

Ansåtze for self-dual Yang-Mills fields

Abstract: A sequenceA1,A2, ... of ansatze for generating self-dual solutions of the Yang-Mills equations is presented. For eachn,An produces a solution depending on two arbitrary functions of three variables. As an application, we see thatA2 generates a static Yang-Mills-Higgs 2-monopole solution.

On the short-run effects of technological progress

Abstract: THIS note presents a simple but apparently new result concerning the short-run impact of technological progress under perfect competition, and uses it to throw light on two classic issues: firstly, the effect of technological progress on the terms of trade, a question raised in recent years by Hicks (1953) and formalized within the framework of the Heckscher-Ohlin model of international trade by Johnson, Mishan and Corden, culminating in the definitive work of Findlay and Grubert (1959); and, secondly, the effect of technological progress on employment, a hotly-debated issue ever since Ricardo's change of heart on the question, which led him to include a new chapter 'On Machinery' in the third edition of his Principles (1821). It will be seen that the answer to the second question hinges on whether it is viewed in a neoclassical or a 'neo-Keynesian' framework, meaning by the latter one in the tradition of Clower (1965), Barro and Grossman (1971) and Malinvaud (1977).

Analysis of the reduction in expression of tetracycline resistance determined by transposon Tn10 in the multicopy state

Abstract: The tet genes of transposon Tn10 have been mapped in a 2,200 bp DNA sequence by analysing deletion and Tn5 insertion mutations. When the tet genes were present on multi-copy plasmids the level of resistance expressed was about ten-fold lower than that determined by a single copy of Tn10 in the E. coli chromosome. The 36K tet protein known to be encoded by R100 in E. coli minicells was not detected when they harboured a multicopy tet plasmid. However, normal high levels of resistance were expressed when the tet genes were recombined into the host chromosome as part of a lambda lysogen, showing that the multicopy effect was phenotypic. Most of the Tn5 insertions and deletions in tet which caused Tcs mutations also prevented expression of high level Tcr from a chromosomal Tn10 element present in the same cell. Only those insertions in the promoter-proximal 90–130 bp of a 1,275 bp HindII fragment known to carry the gene encoding the 36K tet protein did not reduce the single copy Tn10 resistance level. A gene fusion system that results in the constitutive synthesis of β-galactosidase from a tet promoter has been used to assay tet repressor activity. The basal (uninduced) β-galactosidase level in cells carrying multicopy tet plasmids was 10–20 fold lower than those carrying a single copy. The tet:: Tn5 mutants defective in the trans-dominant multicopy effect still made normal amounts of tet repressor showing that repressor overproduction was not responsible for this effect. In addition a repressor-defective constitutive mutant did not exhibit a higher resistance level when located on a multicopy plasmid vector. We postulate that a regulatory mechanism recognises the amino-terminus of the tet structural gene product when attempts are being made to overproduce the protein and prevents further translation.

Limestone solution rates and processes in the Waitomo District, New Zealand

Abstract: Karst solution processes are investigated on Oligocene limestones in the Waitomo district, west central North Island, New Zealand. Estimates of the inputs, throughputs and outputs of water and dissolved calcium and magnesium in two drainage basins were used to establish the rate of limestone solution by autogenic waters. The best estimate for solution loss from the basins during the study year is 69 m3/km2. The potential measurement errors inherent in each parameter used in the erosion rate computations were assessed and the probable maximum and minimum erosion rates were estimated to be 88 and 61 m3/km2. In both basins approximately 67 per cent of the annual solute load is transported by flows greater than the mean annual discharge, over 15 per cent being transported by flood flows that are exceeded only 5 per cent of the time. Almost half of the annual load is transported during the three winter months (June-August), but no one month accounts for more than 18 per cent or less than 2.7 per cent of the annual total. Approximately 37 per cent of solution takes place within the soil profile, and most of the remainder is concentrated in 5–10 m of weathered bedrock (the subcutaneous zone) beneath this. Thus, it is likely that at least 85 per cent of the total solutional erosion contributes to the surface lowering of soil and bedrock.

Determinants of time headway adopted by truck drivers

Abstract: As a measure of driving performance, time headway provides a way of representing the total interaction between a driver, his vehicle and the road environment as well as an exact description of episodes of dangerously close following This paper presents the results of a field experiment on the effects on time headway of prolonged driving in a continuous convoy situation In all, 12 professional truck drivers in two age groups were used Each drove an instrumented 7 ton rigid van-type heavy goods vehicle for 11 hours on each of 4 consecutive days Time headway was measured using a closed-circuit television system designed to provide a continuous record of instantaneous time headway Conditions under which the drivers' following performances were measured were different types of following manoeuvre, prolonged driving and early and late shifts Comparison with the results of an earlier study of incidental episodes of vehicle following provided an evaluation of the effects of infrequent versus continuous fol

A control study of dietary factors in renal stone formation.

Abstract: Summary— Fifty-one first admission renal stone patients and an equal number of controls were interviewed and a dietary history of the average weekly intake was collected from each participant A comparison of the dietary intake per kilogram body weight in each group was made using standard statistical procedures None of the nutrient intakes showed a significant difference, but dietary fibre intake and the percentage of energy provided by carbohydrate were consistently higher in the control group, whereas the percentage of energy provided by fat was consistently higher in the renal stone group

Mössbauer study of europium in fluorozirconate glass

Abstract: 151Eu Mossbauer spectra of fluorozirconate glasses of nominal composition 0.61 ZrF4 · (0.32 − x) BaF2 · x EuF2 · 0.07 ThF4 with x = 0.10 and 0.20 show that Eu2+ is present in sites with isomer shifts in the range −15.5 to −12.9 mm/s, corresponding to EuF bond lengths of 2.3–2.8 A and a coordination number ranging from 8 to 12. The glasses contain a minor amount (∼10%) of Eu3+ in well-defined sites. Effective Debye temperatures deduced from the recoilless fractions for the two ions are θD2+ = 145 K and θD3+ = 261 K. The differences in coordination and bonding indicate that trivalent eurpoium is a network former, whereas the divalent ions are network modifiers.

Medullary carcinoma of the thyroid presenting as tumours of the pharynx and larynx.

Abstract: Two cases of medullary carcinoma of the thyroid presenting as tumours of the pharynx and larynx are described. One patient had a tonsillar mass that resembled a carotid body tumour clinically, radiologically and microscopically. The other had an arytenoid tumour with multiple cervical lymph node metastases but without intrathyroidal carcinoma. The endocrine nature of the neoplasms was indicated by the presence of stromal amyloid, cellular argyrophilia and secretory granules whilst the demonstration of calcitonin and carcinoembryonic antigen provided evidence that they were medullary carcinomas.

Plasmids in epidermolytic strains of Staphylococcus aureus.

Abstract: SUMMARY: Thirty-four epidermolytic toxin-producing strains of Staphylococcus aureus obtained from a variety of sources were screened for the presence of plasmid DNA. All serotype ii toxin producers harboured a large 42 kilobase pairs (kb) plasmid. Elimination of these plasmids resulted in the simultaneous loss of a bacteriocin determinant (Bac+) and type ii toxin production (Tox+ ii). Some strains producing serotype i toxin (Tox+ i) contained similar 42 kb plasmids. Elimination of these plasmids resulted in the loss of only bacteriocin production. Strains producing both toxin serotypes readily lost Tox+ ii and Bac+, which were carried on the same plasmid, but Tox+ i could not be eliminated. Thus Tox+ i was probably chromosomally determined, while Tox+ ii was a plasmid-encoded marker. In some strains cadmium resistance was also linked to the 42 kb plasmid. The 42 kb plasmids from seven strains with different phenotypes were analysed with restriction endonucleases EcoRI and HindIII. The plasmids shared 19 of 22 HindIII fragments indicating that they are closely related to each other.

Polymerisation via macrozwitterions, 1. Ethyl and butyl cyanoacrylates polymerised by triethyl and triphenylphosphines

Abstract: Anionic polymerisation of ethyl and butyl cyanoacrylates in THF initiated by triethyl and triphenylphosphines were followed by adiabatic calorimetry at temperatures between 20 and −95°C. The polymers showed UV absorptions characteristic of phosphonium and cyanoacrylate carbanion end groups, indicating that the growing chains were macrozwitterions. Monomer conversion was quantitative and of 1st order in both monomer and initiator. Other criteria of ‘living’ polymerisation were satisfied, e.g. molecular weights corresponded to one chain per initiator molecule, and indicated that monomer added subsequently was incorporated on to previously formed chains. Assuming the overall rate to be that of propagation yielded values of kp = 1 – 3 · 105 dm3 · mol−1 · s−1 at −78°C, with very low activation energies, i.e. 2,2 and 5,5 kJ · mol−1 for ECA and BCA, respectively. Of a range of inert salts only LiBr significantly reduced the rate of polymerisation.

Antibiotic resistance in Providencia stuartii isolated in hospitals.

Abstract: A total of 238 isolates of Providencia stuartii obtained from infected patients in six Dublin hospitals were grouped by using serological and bacteriocin typing methods and tested for sensitivity to a number of antimicrobial agents. Most isolates were resistant to several of these agents. Resistance to tetracycline, resistance to penicillin, resistance to polymyxin, and probably resistance to nitrofurantoin was intrinsic. Plasmid screening coupled with resistance transfer studies showed that both chromosome-encoded and plasmid-coded resistance mechanisms were clinically important. Ampicillin resistance was both chromosomally and plasmid encoded, whereas resistance to kanamycin and resistance to carbenicillin were exclusively plasmid encoded. Gentamicin resistance was more common than kanamycin resistance, and although gentamicin-resistant strains contained aminoglycoside acetyltransferase activity, no association could be demonstrated with plasmid deoxyribonucleic acid in the strains tested. Unlike minimal inhibitory concentrations for kanamycin, minimal inhibitory concentrations for gentamicin varied over a wide range. P. stuartii isolated obtained from several different countries were tested for comparison. As a group, these strains were less resistant, but they did exhibit similar resistance properties.