Showing papers by "University College Dublin published in 1985"
TL;DR: I binds intercalatively to DNA in low ionic strength solutions and topoisomerisation shows that it unwinds DNA by 22 degrees +/- 1 per residue and that it thermally stabilizes poly[d(A-T)] in a manner closely resembling ethidium.
Abstract: The nature of binding of Ru(phen) 2+ (I), Ru(bipy) 2+ (II), Ru(terpy) 2+ (III) (phen = 1,10-phenanthroline, bipy 3 = 2,2'-bipyridyl, 3 terpy = 2,2'2," - 2 terpyridyl) to DNA, poly[d(G-C)] and poly[d(A-T)] has been compared by absorption, fluorescence, DNA melting and DNA unwinding techniques. I binds intercalatively to DNA in low ionic strength solutions. Topoisomerisation shows that it unwinds DNA by 22 degrees +/- 1 per residue and that it thermally stabilizes poly[d(A-T)] in a manner closely resembling ethidium. Poly[d(A-T)] induces greater spectral changes on I than poly[d(G-C)] and a preference for A-T rich regions is indicated. I binding is very sensitive to Mg2+ concentration. In contrast to I the binding of II and III appears to be mainly electrostatic in nature, and causes no unwinding. There is no evidence for the binding of the neutral Ru(phen)2 (CN)2 or Ru(bipy)2 (CN)2 complexes. DNA is cleaved, upon visible irradiation of aerated solutions, in the presence of either I or II.
808 citations
TL;DR: Binding of 5,10,15,20-tetrakis (N-methylpyridinium-4-yl)porphyrin and its zinc complex (ZnTMPyP4+) to DNA is demonstrated by their coelectrophoresis and by absorption and fluorescence spectroscopic methods.
Abstract: Binding of 5,10,15,20-tetrakis (N-methylpyridinium-4-yl)porphyrin (H2TMPyP4+) and its zinc complex (ZnTMPyP4+) to DNA is demonstrated by their coelectrophoresis and by absorption and fluorescence spectroscopic methods. Topoisomerisation of pBR322 DNA shows that H2TMPyP4+ unwinds DNA as efficiently as ethidium bromide showing that it intercalates at many sites. ZnTMPyP4+ may cause limited unwinding. Marked changes in the fluorescence spectra of the porphyrins are found in the presence of DNA. The fluorescence intensity of either H2TMPyP4+ or ZnTMPyP4+ is enhanced in the presence of poly (d(A-T)), whereas in the presence of poly (d(G-C] the fluorescence intensity of ZnTMPyP4+ is only slightly affected and that of H2TMPyP4+ markedly reduced. Both the porphyrins photosensitize the cleavage of DNA in aerated solution upon visible light irradiation.
200 citations
122 citations
TL;DR: In this article, a mathematical model based on three fundamental equations, the Hagen Poiseulle equation for flow of fluids in pipes, Darcy's law of fluid flow through porous media to describe the flow of oil through the interkernel voids, and a modified form of Terzaghi's equation for the consolidation of saturated soils, was also used to satisfactorily predict the performance of commercial hydraulic presses and screw expellers.
105 citations
TL;DR: Of the various initial factors studied, persistence of pain and the magnitude and extent of ECG ST-T changes were the only predictors of an unfavorable outcome.
101 citations
TL;DR: A new iterative polyexponential curve stripping technique for the provision of initial pharmacokinetic parameter estimates has been developed and the parameter estimates which it provides are free of the bias which may arise in conventional curve stripping.
90 citations
88 citations
TL;DR: In this paper, the temperature dependence of the Gd magnetization is deduced from the exchange interactions between Gd and Fe spins, and the main axis of the electric field gradient is shown to have different directions at the two rare earth sites.
70 citations
TL;DR: A carbon dioxide trap designed to capture Ixodes ricinus over periods of up to 7 days is described, which compared favourably with blanket dragging and flagging in areas of high tick density and was also surprisingly efficient for larvae.
Abstract: A carbon dioxide trap designed to captureIxodes ricinus over periods of up to 7 days is described. The trap compared favourably with blanket dragging and flagging in areas of high tick density, particularly on rough ground and for adult ticks; it was also surprisingly efficient for larvae. Ticks appeared to be captured throughout the 7-day trapping period. The maximum attraction distance recorded for adult female ticks was 3.5 m and for nymphs 1.0 m. Trapping rates were influenced by air temperature.
69 citations
TL;DR: The results indicate that the variation in whole-plant susceptibility to the herbicide is not caused by differences in the degree to which the glutamine synthetases from these plants are inhibited.
64 citations
TL;DR: In this article, the 1,3-dipolar cycloreversion pathway of the pentazole anion (N 5 − ) to the azide anion plus dinitrogen (N 2 ) has been investigated using ab initio methods.
TL;DR: The effect of organic matter, soil moisture, pH and the indigenous soil nematode density on the distribution of nematophagous fungi has been examined to indicate which of these major factors are important in their distribution.
Abstract: The effect of organic matter, soil moisture, pH and the indigenous soil nematode density on the distribution of nematophagous fungi has been examined. Using 206 samples of soil and organic material, the presence and absence of groups and individual species of nematophagous fungi have been compared statistically to indicate which of these major factors are important in their distribution. The presence of predatory fungi was more influenced by pH and moisture than the other soil factors, while the presence of the conidia-forming endoparasites was influenced by organic matter. The presence of obligate parasites was associated with high soil nematode densities while facultative predators were independent of nematode density. Endoparasites with conidia that do not attract nematodes were found in soils with a higher nematode density than those species producing nematode-attracting conidia. This would increase the chance of infection by the random ingestion of the conidia by a suitable host. Non-spontaneous trap forming predators were isolated from soils with low organic matter and low moisture. These species are able to compete well saprophytically under such conditions, and when nutrients or moisture temporarily improve, they are able to maintain their competitive advantage by utilizing the expanding nematode population. Spontaneous trap-forming predators were found in soils with relatively high organic matter and moisture. In such soils there is a rich microbial flora and fauna, and the ability to form traps spontaneously offers these predators a direct competitive advantage over saprophytes and non-spontaneous trap-forming predatory fungi. Attempts to model the data were generally unsuccessful due to the qualitative-quantitative nature of the data, the small data base and the resulting high number of distinct co-variate patterns formed by the independent variables. The methods of isolation used are compared with earlier investigations where isolations were made from extracts taken from large weights of sample material.
TL;DR: Twenty-seven adult rams were raised under natural photoperiod and were trained to serve into an artificial vagina and had no significant effect on semen volume, motility and percentage dead or abnormal cells.
TL;DR: In an environment of sluggish overall growth, such as has characterised most of the world in the past eight years, structural adjustment may be extremely painful, even though it results from a boom elsewhere in the economy as mentioned in this paper.
Abstract: When the average rate of growth of an economy is high, considerable changes in the relative sizes of different sectors can often be accommodated without great cost. However, in an environment of sluggish overall growth, such as has characterised most of the world in the past eight years, structural adjustment may be extremely painful, even though it results from a boom elsewhere in the economy. The problems are likely to be particularly acute if the boom takes the form of a rapid and unanticipated expansion of a small number of sectors, as typically follows the exploitation of natural resource discoveries.
TL;DR: In this paper, the lower-lying electronic states of dichlorocarbene have been studied by ab initio methods at different levels of accuracy, and the vibrational frequencies of CCl2 in both 1A1 and 1B1 states were calculated and compared with experiment.
Journal Article•
TL;DR: Although the growth of SCLC cells in a clonogenic assay may be of value in chemotherapy selection, the established cell lines provide a model for studying mechanisms of drug and radiation sensitivity; and drug metabolism, and the establishment of cell lines has clearly indicated the considerable heterogeneity that exists in SclC.
TL;DR: In this article, it was shown that the characters of the complex irreducible characters of O(n, q) are real-valued in the split orthogonal groups of degree n over GF(q) provided that q z 1 (mod 4).
TL;DR: In this article, an extracellular α-amylase and α-glucosidase were produced by Lipomyces starkeyi CBS 1809 in a medium containing maize starch and soya bean meal.
Abstract: Thermostable, extracellular α-amylase and α-glucosidase were produced byLipomyces starkeyi CBS 1809 in a medium containing maize starch and soya bean meal. Contrary to published findings which suggested a single cell-bound amylolytic system for another strain ofL. starkeyi, this study revealed the presence of two enzymes — an α-amylase and an α-glucosidase inL. starkeyi CBS 1809. The enzymes were separated by solvent and salt precipitation and ion-exchange chromatography on DEAE-Biogel-A. The α-amylase and α-glucosidase had pH optima at 4.0 and 4.5 and temperature optima at 70°C and 60°C, respectively. While the low pH optima are not unique the enzymes are very distinctive in yeasts in having very high temperature optima. The α-glucosidase had highest activities on maltose and isomaltose (100) with relative rates of activity on maltotriose, isomaltotriose and p-nitrophenyl-α-d-glucoside of 59, 48 and 22, respectively. It was inactive towards sucrose. Both the α-amylase and α-glucosidase ofL. starkeyi were located extracellularly and had molecular weights of 76,000 and 35,000, respectively.
TL;DR: In this article, the authors found that NH3 volatilization was controlled by buffered CEC and initial pH (R2= 72-87%) and was related to variations in soil organic matter and texture.
Abstract: SUMMARY
Mean NH3 losses after nine days incubation at 18°C and 60% FC were 3.1±2.9% and 7.6±6.0% of applied urea-N from the pasture and tillage counterparts of 10 soil series. These losses were highly correlated with buffered CEC and maximal pH values (pHm) generated three days after urea application. NH3 volatilization was apparently controlled by buffered CEC and initial pH (R2= 72–87%) and was related to variations in soil organic matter and texture (R2= 77–81%). Losses in the acid pasture soils were attributed largely to initial pH differences, and in the tillage soils to buffered CEC only.
Evolution was greater from the tillage than from the pasture equivalent in eight series. This was attributed to differences in CEC, including buffered CEC and pH-dependent charge, caused by differences in OM content primarily but also in texture between the two soil groups. Differences in NH3 evolution from urea in pasture and tillage soils, in general, are not related to pH differences.
TL;DR: The value of short-term and long-term low-dose vitamin D supplementation (20 μg D3 daily) is demonstrated in elderly subjects and readily restored serum 25-hydroxy-vitamin D values to normal, and ameliorated biochemical abnormalities of calcium, phosphate, and alkaline phosphatase, consistent with healing of mild osteomalacia.
Abstract: Conflicting opinions are held on the efficacy and safety of low-dose oral vitamin D supplementation. In this study, the value of short-term and long-term low-dose vitamin D supplementation (20 μg D3 daily) is demonstrated in elderly subjects. Short-term therapy readily restored serum 25-hydroxy-vitamin D (25OHD) values to normal, and ameliorated biochemical abnormalities of calcium, phosphate, and alkaline phosphatase, consistent with healing of mild osteomalacia. Prolonged therapy (16 months) maintained serum 25OHD levels within the young adult range, and was not associated with hypercalcemia. Withdrawal of therapy was associated with a steady decline in serum 25OHD levels. Low-dose vitamin D supplementation is recommended for elderly subjects to prevent the development of hypovitaminosis D osteopathy.
TL;DR: In this paper, the authors used radiocarbon dating to identify three chronostratigraphic units: 13000-11000, 9000-7000, and 2100 years BP to the present.
Abstract: Examination of the diamondiferous sediments of the Birim River floodplain in Ghana using radiocarbon dating allows the recognition of three chronostratigraphic units: 13000–11000, 9000–7000, and 2100 years BP to the present, while older sediments rest on bedrock benches and form terraces. The late Pleistocene sediments infill deeper, scour channels, are generally both thicker and coarser, and return higher diamond grades. One thousand nine hundred samples from 700 boreholes indicate that diamond grade is influenced by bedrock consistency, gravel thickness, gravel calibre, and stratigraphic position, but other external factors include supply of coarse quartz from bedrock, valley morphology, and the location of tributary junctions and diamond sources. The influence of palaeoenvironmental conditions on fluvial deposition and placer formation in W Africa appears widespread and relates to the known late Quaternary climatic changes established from Lake Bosumtwi, Ghana, and from the Sahara.
TL;DR: In this paper, the authors used dark-grown, decapitated corn seedlings that had been grown without nitrogen to characterize relationships among uptake, translocation and in vivo reduction of [' 5N] nitrate during induction of the nitrate uptake process and throughout the subsequent steady-state period.
Abstract: Dark-grown, decapitated corn (Zea mays L.) seedlings that had been grown without nitrogen were used to characterize relationships among uptake, translocation and in vivo reduction of [' 5N] nitrate during induction of the nitrate uptake process and throughout the subsequent steady-state period. During induction, cumulative nitrate reduction increased from less than 20% of cumulative nitrate uptake to about 30%. Concurrently, translocation of nitrate increased from less than 30% to over 50% of that absorbed. During the following steady-state period, partitioning of incoming nitrate between reduction and translocation remained relatively constant. Initially, removal of the endosperm had little effect on nitrate uptake, but by 6 h cumulative uptake had been depressed 30% relative to control plants. In contrast, endosperm removal limited nitrate reduction within 1 h, and as a consequence nitrate reduction during the 6 h exposure period was 60% less in endosperm-free tissues. Collectively these observations indicate that nitrate uptake and reduction are independent processes, since they develop at dissimilar rates upon initial exposure to nitrate, and since they differ markedly in response to endosperm removal. However, the constancy of nitrate reduction during steady-state uptake (30% of incoming nitrate), does reflect an association between the two processes.
TL;DR: Analysis of questionnaire responses showed reasonable accord with the findings of the designers of the SADQ, suggesting that the questionnaire is a useful and valid instrument for the investigation of alcoholics.
Abstract: Summary
Validation of the Severity of Alcohol Dependence Questionnaire (SADQ) was attempted in a sample of 102 Irish problem drinkers. Analysis of questionnaire responses showed reasonable accord with the findings of the designers of the SADQ, suggesting that the questionnaire is a useful and valid instrument for the investigation of alcoholics. The findings gave qualified support for the concept of the alcohol dependence syndrome. Maximum agreement with a findings gave qualified support for the concept of the alcohol dependence syndrome. Maximum agreement with a clinician's rating of moderate and severe dependence was achieved at a cut-off score of 30 on the SADQ. Results also suggested it might be possible to use the SADQ to distinguish between minimal and mild to moderate dependence.
TL;DR: A comparison of sampling methods showed that the previously observed small size of the spring peak relative to the midsummer peak is not a sampling artifact and is a genuine measure of the prevalence of active larvae.
Abstract: The activity of larvalI. ricinus was studied in the field and on experimental plots in an attempt to determine the origin and population dynamics of larvae at different times of the year. A comparison of sampling methods showed that the previously observed small size of the spring peak relative to the midsummer peak is not a sampling artifact and is a genuine measure of the prevalence of active larvae. It was established that spring-active larvae are derived from spring-fed adults which contribute comparatively few larvae to the midsummer peak. The small size of the spring peak is probably due to relatively poor activation and survival of available larvae at this time. A distinct emergence and activation of larvae, almost certainly derived from autumn-fed adults, was detected in July, which is before the diapause period. Such larvae would be capable of producing spring nymphs and this is probably a major means of transfer of ticks between spring and autumn populations.
TL;DR: In this article, the geomorphology and diamond distribution within the Koidu alluvial diamond field in Sierra Leone are examined to provide a methodology for palaeoplacer appraisal within a humid tropical environment of diverse relief and headwater drainage containing local diamond sources.
Abstract: The geomorphology and diamond distribution within the Koidu alluvial diamond field in Sierra Leone are examined to provide a methodology for palaeoplacer appraisal within a humid tropical environment of diverse relief and headwater drainage containing local diamond sources. A morphogenetic terrain model is proposed for use in devising prospecting programmes, based on geomorphological mapping and sediment analysis of terrain units mapped at 1:1250. Valley floors including headwater swamps and stream floodplains provide a radiocarbon-dated late Quaternary stratigraphic framework for deductions concerning interfluvial domains containing remnant river terraces, and colluvial stoneline deposits interspersed with non-alluvial erosional slopes. Planar interfluves as well as piedmont ‘glacis’ contain alluvial indicators within gravels composed of bedrock quartz and iron concretions derived from former landsurfaces. A process history for the interfluvial domain indicates downwasting and diagenesis of ancient degraded alluvials, lateral shifts of drainage lines and continued supply of diamonds from erosion of local sources, the ‘stonelines’ functioning as feeders of coarse clasts from the interfluves towards the valley floors. The use of geomorphology to provide descriptive and genetic terrain models to guide prospecting for alluvial placers is advocated as a standard procedure for use by mining geologists.
TL;DR: In this article, the energy barrier for the rearrangement of methylnitrene to methylenimine is calculated to be 9.5 kcal/mol at the MP4SDQ/6-31G/HF/3-21G level.
TL;DR: The mean urease activities of the pasture and tillage counterparts of 10 soil series were 103 ± 44 and 75 ± 26 μg urea-N hydrol, respectively as discussed by the authors.
Abstract: The mean urease activities of the pasture and tillage counterparts of 10 soil series were 103 ± 44 and 75 ± 26 μg urea‐N hydrol. g‐1 h‐1, respectively. Significantly (p<0.01) greater activity was recorded in the pasture variety of 8 series and in the tillage variety of 2 series. Multiple regression analysis showed that variations in the activities of the pasture soils (R2 = 95.9%) and of 2 the tillage soils (R2 = 97.3%) was attributable to variations in total‐N, unbuffered and pH‐dependent CEC, pH and silt, as well as C:N ratio in the case of the pasture group. The best‐fit regression for the latter soils was obtained when individual cations replaced CEC parameters (R2 = 99.8%). Individual soil properties each accounted for a small proportion of the total variation. The results suggest that agricultural soils should be grouped by land‐use for best prediction of their urease activities. Differences between the activities of the pasture and tillage soils were highly correlated with the differences ...
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