Showing papers by "Trinity College, Dublin published in 1990"

Magnetic properties of a new series of rare-earth iron nitrides: R2Fe17Ny(y approximately 2.6)

Abstract: A series of interstitial ternary nitrides R2Fe17Ny with 23

CASS - Middleware for Mobile Context-Aware Applications

Abstract: Among the difficulties faced by designers of mobile context-aware applications is the increased burden of having to deal with context and also the processing and memory constraints of small mobile computers. Although progress has been made in the area of frameworks and toolkits for contextawareness, there is still a need for middleware that supports higher-level context abstractions and is both flexible and extensible in its treatment of

Localizing multiple X chromosome-linked retinitis pigmentosa loci using multilocus homogeneity tests

Abstract: Multilocus linkage analysis of 62 family pedigrees with X chromosome-linked retinitis pigmentosa (XLRP) was undertaken to determine the presence of possible multiple disease loci and to reliably estimate their map location. Multilocus homogeneity tests furnished convincing evidence for the presence of two XLRP loci, the likelihood ratio being 6.4 x 10(9):1 in favor of two versus a single XLRP locus and gave accurate estimates for their map location. In 60-75% of the families, location of an XLRP gene was estimated at 1 centimorgan distal to OTC, and in 25-40% of the families, an XLRP locus was located halfway between DXS14 (p58-1) and DXZ1 (Xcen), with an estimated recombination fraction of 25% between the two XLRP loci. There is also good evidence for a third XLRP locus, midway between DXS28 (C7) and DXS164 (pERT87), supported by a likelihood ratio of 293:1 for three versus two XLRP loci.

Climatic and biotic change in the late Triassic

Abstract: Generally arid conditions that pervaded much of Europe and North America during the late Triassic were interrupted by a wet monsoonal climatic phase during Middle and Late Carnian times. Extensive fluviatile sandstones deposited at this time throughout the region, occur within a thick sequence of playa-lake mudstones. The sandstones occasionally contain kaolinite, suggesting a humid climate. An extreme δ 13 C depletion in a shallow marine sequence of this age in Israel has been interpreted as evidence for an influx of freshwater. A widespread change from carbonates to clastics in marine sequences at this time may also be climate-related. Water-course cave systems in limestone areas exposed during the late Triassic indicate high levels of runoff during the Middle and Late Carnian. The marine invertebrate fauna shows a significant turnover at the end of the Early Carnian. The terrestrial fauna and flora were relatively unaffected at this time but subsequently diversified prior to a major biotic turnover at the Carnian-Norian boundary. These periods of biotic change appear to be synchronous with the onset and cessation of a Carnian humid phase. The change to a monsoonal climate during this interval has been documented over more than 90° of longitude between 5° and 50° north of the Triassic equator. It may have been caused by rising atmospheric CO 2 levels due to volcanism associated with the incipient dispersal of Pangaea.

The coagulase of Staphylococcus aureus 8325-4. Sequence analysis and virulence of site-specific coagulase-deficient mutants.

Abstract: Summary The sequence of the coagulase gene (coa) from Staphylococcus aureus strain 8325-4 is reported. The deduced amino acid sequence of the coagulase protein is compared with previously reported sequences of coagulases from strains 213 and BB. The secreted mature forms of coagulase proteins are composed of three distinct segments: (i) the N-terminal 150–270 residues, which are c. 50% identical, (ii) a central region with high (>90%) residue identities, and (iii) a C-terminal region composed of repeated 27-amino-acid residue sequences. The variable N-terminal sequences are probably responsible for antigenic differences among coagulases of different serotype. The region of coagulase which binds to prothrombin and activates it to form staphylothrombin is also located in the N-terminal half of the protein. A site-specific substitution mutation in the coa gene, which abolished plasma clotting activity, was isolated by recombinational allele-replacement in strains 8325-4 and M60. The Coa− mutants did not show diminished virulence in subcutaneous and intramammary infections of mice. No evidence for a role for coagulase in virulence of toxigenic or non-toxigenic strains was obtained. This contradicts findings of several groups using Coa− mutants generated by chemical mutagenesis and suggests that the earlier results were obtained with strains that had suffered additional mutations in virulence-related genes.

Rigidity loss transition in a disordered 2D froth.

Abstract: Disordered two-dimensional soap froth has been simulated, with a gas fraction \ensuremath{\varphi} less than unity. Upon decreasing \ensuremath{\varphi}, it is found that the system loses its rigidity at ${\mathrm{\ensuremath{\varphi}}}_{\mathit{c}}$=0.84. This value is identified with the dense random packing of hard disks. Results are presented for the variation of yield stress and shear modulus, the latter being tentatively related to elastic-network theory.

Magnetization of a Dy(Fe11Ti) single crystal.

Abstract: Magnetization curves have been measured in the temperature range from 4.2 to 300 K along the (100), (110), and (001) directions of a Dy(Fe{sub 11}Ti) single crystal in fields up to 7 T. The magnetic moment is along (100) below 58 K and parallel to the {bold c} axis above 200 K. Between the two spin-reorientation transitions (first order at 58 K, second order at 200 K) there is a canted spin structure where the net magnetization lies in a (010) plane and is inclined at an angle to the {bold c} axis. Three first-order magnetization processes are observed as a function of applied field below 150 K. All the data are used to derive a set of five crystal-field coefficients at the single rare-earth site of the ThMn{sub 12} structure: {ital A}{sub 20}={minus}32.3 K{ital a}{sub 0}{sup {minus}2}, {ital A}{sub 40}={minus}12.4 K{ital a}{sub 0}{sup {minus}4}, {ital A}{sub 44}=118 K{ital a}{sub 0}{sup {minus}4}, {ital A}{sub 60}=2.56 K{ital a}{sub 0}{sup {minus}6}, {ital A}{sub 64}=0.64 K{ital a}{sub 0}{sup {minus}6}. Spin reorientation observed in the other members of the {ital R}(Fe{sub 11}Ti) ({ital R}==rare earth) series, except those in Tb(Fe{sub 11}Ti), are explained by the same crystal-field coefficients.

SPIDER—an interactive statistical tool for the analysis of spatially distributed data

Abstract: Interactive statistical graphics are reviewed in the contexts of spatial data and geographical information systems (GIS). GIS provide the user with an active geographical view of the data—a map that can be used as an entry point to the data base. Prototype software—SPIDER—illustrates the possibilities of using statistical graphics as further views of the data, which can be made active and thus provide alternative means of querying the data. These views can be cross-referenced by 'linking'. It is argued that such a system can provide a very rich environment for pursuing exploratory statistical analysis of spatial data.

Stimulating reporting of adverse drug reactions by using a fee.

Abstract: more commonly associated with certain cephalosporins having the N-methylthiotetrazole side chain-' but have been noted with otherssuch as cefuroximelacking this side chain.23 Some investigators have suggested that the pharmacokinetic profile of an antibiotic is important if it is to be given only preoperatively and have advocated the use of antibiotics with prolonged elimination half lives-for example, ceftriaxone,\" which is not available in Britain. Our results imply that this is not necessary for operations lasting up to 90 minutes. The half lives of both cephalosporins used here are in the order of one to one and a half hours. Cefotaxime, however, undergoes desacetylation to a metabolite, desacetylcefotaxime, which has broad spectrum antibiotic activity and hence prolongs the duration of antibiotic activity of the parent drug.24 Nevertheless, for operations which extend beyond 90 minutes our results suggest that a peroperative \"topping up\" dose may be beneficial (though only 107 of 907 (11 8%) operations in this study were of greater than two hours' duration). It is evident that prophylactic postoperative doses of cefuroxime plus metronidazole confer no additional benefit over a single preoperative dose of cefotaxime plus metronidazole.

Autosomal dominant retinitis pigmentosa: absence of the rhodopsin proline----histidine substitution (codon 23) in pedigrees from Europe.

Abstract: In exon 1 at codon 23 of the rhodopsin gene, a mutation resulting in a proline-to-histidine substitution has previously been observed in approximately 12% of American autosomal dominant retinitis pigmentosa (ADRP) patients The region around the site of this mutation in the rhodopsin gene has been amplified and analyzed in affected individuals from 91 European ADRP pedigrees The codon 23 mutation has been found to be absent in all cases, including a large Irish pedigree in which the disease gene has previously been shown to be closely linked to the rhodopsin locus This indicates the presence of either allelic or nonallelic heterogeneity in ADRP

Characterization of PBSX, a defective prophage of Bacillus subtilis

Abstract: PBSX, a defective Bacillus subtilis prophage, maps to the metA-metC region of the chromosome. DNA (33 kilobases) from this region of the chromosome was cloned and analyzed by insertional mutagenesis with the integrating plasmid pWD3. This plasmid had a promoterless alpha-amylase gene (amyL) that provided information on the direction and level of transcription at the site of integration. Transcription under the control of the PBSX repressor proceeded in the direction metA to metC over a distance of at least 18 kilobases. Electrophoretic analysis of proteins produced by different integrant strains upon PBSX induction and by fragments subcloned in Escherichia coli allowed the identification of early and late regions of the prophage. A set of contiguous fragments directing mutagenic integration suggested that the minimum size of an operon that encodes phage structural proteins is 19 kilobases. The adaptation of PBSX transcriptional and replicational functions to a chromosomally based, thermoinducible expression system is discussed.

Story Grammar Effective Literature Instruction for High School Students with Learning Disabilities

Abstract: This study examined the effectiveness of an instructional strategy for teaching comprehension of literature to 8 high school students with learning disabilities. The strategy integrated recent advances in cognitive psychology with empirically derived principles of effective instruction. The texts included short stories from middle school and high school literature anthologies. A modified multiple baseline design was utilized. Results indicated improvements in the students' ability to answer questions based on the stories read.

Lipid lowering drugs.

Abstract: L donovani and that malnutrition is an important factor determining whether the infection will become clinic? ally manifest. Malnutrition could be at least partly responsible for the occurrence of kala-azar in adult Indians and east Africans. It may be that leishmania is like Mycobacterium tuberculosis and never disappears completely once the amastigotes have established themselves in the body. Several patients who had never had any symptoms of the disease developed kala-azar after immunosuppres sion. I personally attended a man who developed kala azar in England 14 years after he had left an area where . it was endemic. Brazil's control programme for kala-azar incorpo? rates three measures: treating patients with the first line drug meglumine antimonate provided by the ministry, detecting and destroying infected dogs, and spraying homes and gardens with dicophane (DDT) to combat the vector Lutzomyia longipalpis. It has been suggested that under epidemic conditions most infected children should be treated at home rather than over? strain hospital services. This is logical as hospitals are full of bacterial pathogens to which patients with active kala-azar are very susceptible. Children tolerate anti? monial drugs better than adults, but certain basic rules must be obeyed. For outpatient treatment the daily injection is best given at the end of the day so that the patients can rest afterwards, and it must be given slowly if administered intravenously. Patients with cardiac, renal, or hepatic dysfunction must be carefully screened before being given antimonial drugs and alcohol must be avoided during treatment. I shall have more to say about antimonial drugs in my next communication.

The role of nutrition in neural tube defects.

Abstract: GENETIC FACTORS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . .. . . . . . .. . . . . . . .. . . . . . . . . 278 ENVIRONMENTAL FACTORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 279 Nutrient Excess 282 Nutrient Deficiency...... 283

The Solund-Stavfjord ophiolite complex and associated rocks, West Norwegian Caledonides; geology, geochemistry and tectonic environment

Abstract: Metabasalts of the Upper Ordovician Solund-Stavfjord Ophiolite Complex of the westernmost Norwegian Caledonides, show N-to E-MORB affinity, with high Th/Ta (or Nb) ratios giving evidence of subduction influence. The Solund–Stavfjord Ophiolite Complex is overlain by a heterogeneous assemblage of sedimentary and volcanic rocks, the Stavenes Group, of which the Heggoy Formation of metasandstones and phyllites conformably overlies the metabasalts of the Solund–Stavfjord Ophiolite Complex. The Heggoy Formation contains, in places, abundant metabasalt pillow lavas and minor intrusions, geochemically similar to those of the Solund–Stavfjord Ophiolite Complex, and basic metavolcaniclastites of island arc tholeiite (IAT) composition. This indicates that the Solund–Stavfjord Ophiolite Complex and Heggoy Formation developed in a marginal basin between a continental margin and an active subduction system, for which the present-day Andaman Sea may provide a realistic model. The other magmatic rocks of the Stavenes Group, showing both calc-alkaline and alkaline affinities, are less well time-constrained, but they are thought to represent an advanced stage of the island arc development, and ocean island build-up, respectively.

Buspirone impairment of performance of passive avoidance and spatial learning tasks in the rat.

Abstract: The effects of buspirone on the execution of step-through passive avoidance and spatial navigation learning tasks were assessed. In view of the anxiolytic properties of the drug, its effects on shock induced ultrasonic vocalizations and shock suppressed locomotor activity in a hole-board were also determined. Doses (0.5, 1 and 2 mg/kg, IP) which did not affect exploratory activity in a novel environment (light/dark box and hole-board apparatus) were used. Buspirone (1 and 2 mg/kg) impaired performance on the 24 h passive avoidance recall test when given prior to the training and the test sessions or prior to the test session only but not when given before the training trial only. The stress response to the mild footshock, as measured in terms of suppressed locomotor activity in the hole-board apparatus and post-shock ultrasonic vocalizations, was reduced by buspirone (at 1 and 2 mg/kg, respectively), indicating that its effect on behavior in the passive avoidance learning task is probably due to its anxiolytic properties. Evidence for a possible amnesic effect of buspirone (2 mg/kg) was found on the acquisition and probe test trials in the spatial navigation task. During training the latency to find a submerged escape platform in a water maze was increased. Performance on a probe test was also impaired but this effect was not apparent in animals which had received buspirone only prior to the probe test. Although these changes may be attributable to alterations in many aspects of cognitive processing, the possibility of a direct effect on memory warrants further investigation.

Two subcellular locations for peripheral-type benzodiazepine acceptors in rat liver.

Abstract: Subcellular fractionation of rat liver by differential centrifugation showed the mitochondrial fractions to have the greatest enrichment of ‘peripheral-type’ benzodiazepine acceptor. Two peaks of acceptor sites were found on isopycnic density-gradient centrifugation, one peak (ϱ= 1.19 g/ml) corresponding to the peak of mitochondria as judged by marker enzyme distribution and by transmission electron microscopy, and the other peak (ϱ= 1.17 g/ml) which is not mitochondrial as judged by the lack of mitochondrial enzyme markers. Whereas the density of the mitochondrial acceptor was sensitive to sonication and was shown to have an outer-membrane location, the density of the non-mitochondrial acceptor was insensitive to sonication. The non-mitochondrial acceptor was shown not to be associated with Golgi, lysosomes, rough endoplasmic reticular microsomes, peroxisomes, or some type of plasma membranes, as jugged by differences in the distribution of marker activities. No enrichment of benzodiazepine acceptor was found in the purified nuclear fraction. Both acceptors were shown to be peripheral-type high-affinity acceptors as judged by ligand specificities and by photoaffinity labelling.

Enhanced secretion of prostaglandin E2 by tissue-fixed macrophages in colonic carcinoma.

Abstract: Prostaglandin E2 (PGE2) secretion by peripheral blood and tissue-fixed macrophages from patients with colorectal carcinoma was assessed. There was no significant difference between PGE2 production by peripheral blood mononuclear cells between patients with colorectal carcinoma and normal controls. However, secretion of PGE2 by tissue-fixed macrophages from within the colorectal carcinomata in response to opsonised zymosan was significantly higher than in the uninvolved colonic tissue. PGE2 production by tissue-fixed macrophages from within colonic polyps was found to be normal. These results could not be explained on the basis of increased availability of substrate arachidonic acid since addition of excess arachidonic acid resulted in similar findings. The enhanced production of PGE2 correlated with Dukes staging but not the level of differentiation. The production of PGE2 from epithelial cells in response to ionophore A23187 was not significantly enhanced. Leukotriene B4 secretion by intestinal macrophages in response to opsonised zymosan was not significantly elevated in the colonic tumour tissue. Modulation of levels of prostaglandin production within colonic tumours may play a role in the rate of growth and vascularity of these tumours and in the regulation of the local immune response to malignancy.

Insect infestations of small corpses

Abstract: Reproducible studies of the insects associated with small (< 1 kg) corpses are hampered by dramatic variation, for no obvious reason, in the background carrion-breeding fauna This variation can lead to undue emphasis being attached to the results from exposure of one, or a small number, of corpses An experiment with much larger numbers of mice (319) and birds (38) has shown that in eastern Ireland there are at least 29 species of carrion insect (excluding Coleoptera) breeding in such corpses, many of them only in deciduous woodland, where the greatest number and variety of small vertebrates would be found Inventories of the post-mortem fates of mice and birds are drawn up, and the effects of competition assessed by experiment Some species of sarcophagid fly larvae kill their competitors Of the 14 Irish sacrophagine species, only four bred in corpses There was a gross imbalance of Calliphora spp, with hardly any C vomitoria in any bait tested

Methylmalonyl-CoA mutase (EC 5.4.99.2) and methionine synthetase (EC 2.1.1.13) in the tissues of cobalt-vitamin B12 deficient sheep.

Abstract: The changes in the activities of the two vitamin B12-dependent enzymes methylmalonyl-CoA mutase (EC 5.4.99.2) and methionine synthetase (5-methyltetrahydrofolate-homocysteine methyltransferase, EC 2.1.1.13) are described in two groups of sheep maintained for 20 weeks on either a cobalt-deficient or a Co-sufficient whole-barley diet. At the end of that period, the plasma concentrations of vitamin B12 were depressed and those of methylmalonic acid were raised in the Co-deficient group. During the course of the experiment hepatic holo-mutase activity, measured on biopsy samples, declined in Co-deficient animals with a half-life of 73 d. There was a similar, but slower decline in lymphocyte holo-mutase activity which fell with a half-life of 125 d. At slaughter, there was no difference between Co-sufficient and Co-deficient animals in total mutase activity in liver, kidney, brain and spinal cord. In contrast, the total-synthetase activity of liver and kidney was reduced by 60 and 30% respectively in the Co-deficient animals. There was no change in either group of animals in total-synthetase activity, or in either holo-mutase or holo-synthetase activity, in brain and spinal cord. In the Co-deficient animals, holo-mutase and holo-synthetase activities in liver, the tissue with the greatest activity of both enzymes, fell to 25 and 39% respectively, of that of Co-sufficient animals. The corresponding reductions for kidney were 12 and 51% respectively. These results indicated that activity of both holoenzymes is greatly reduced in Co-deficient sheep.