Showing papers by "Trinity College, Dublin published in 1991"
TL;DR: Different PR methods should be seen not as being more proportional or less proportional than each other but as embodying different ideas as to what maximizing proportionality means and, by extension, what minimizing disproportionality means as discussed by the authors.
797 citations
TL;DR: A family of highly conserved, Enterobacterial Repetitive Intergenic Consensus (ERIC) sequences are described, 14 of which have been identified in Escherichia coli and Salmonella typhimurium and a further three in other enterobacterial species (Yersinia pseudotubercuiosis, Kiebsiella pneumoniae and Vibrio cholerae).
Abstract: We describe a family of highly conserved, Enterobacterial Repetitive Intergenic Consensus (ERIC) sequences, 14 of which have been identified in Escherichia coli and Salmonella typhimurium and a further three in other enterobacterial species (Yersinia pseudotuberculosis, Klebsiella pneumoniae and Vibrio cholerae). ERIC sequences are 126 bp long and appear to be restricted to transcribed regions of the genome, either in intergenic regions of polycistronic operons or in untranslated regions upstream or downstream of open reading frames. ERIC sequences are highly conserved at the nucleotide sequence level but their chromosomal locations differ between species. Several features of ERIC sequences resemble those of REP sequences (Stern et al., 1984) although the nucleotide sequence is entirely different. The question of whether ERICs have a specific function, or represent a form of 'selfish' DNA, is discussed.
551 citations
TL;DR: A three-base-pair deletion is identified which results in the loss of one of a pair of highly conserved cysteine residues in the predicted third transmem-brane domain of peripherin, and suggests that mutant peripherin gives rise to retinitis pigmentosa.
Abstract: THE group of retinopathies termed retinitis pigmentosa (RP) greatly contribute to visual dysfunction in man with a frequency of roughly 1 in 4,000 (refs 1, 2). We mapped the first autosomal dominant RP (adRP) gene to chromosome 3q (refs 3, 4), close to the gene encoding rhodopsin, a rod photoreceptor pigment protein. Subsequently, mutations in this gene have been implicated as responsible for some forms of adRP5–9. Another adRP gene has been mapped to chromosome 8p (ref. 10). A third adRP gene in a large Irish pedigree has been mapped to chromosome 6p (refs 11,12), showing tight linkage with the gene for peripherin13,14, a photoreceptor cell-specific glycoprotein, which is thus a strong candidate for the defective gene. We have now identified a three-base-pair deletion which results in the loss of one of a pair of highly conserved cysteine residues in the predicted third transmem-brane domain of peripherin. This deletion segregates with the disease phenotype but is not present in unaffected controls, and suggests that mutant peripherin gives rise to retinitis pigmentosa.
396 citations
TL;DR: Aberbach as discussed by the authors examines the reasons behind the surprising growth of congressional oversight and concludes that the U.S. government system was not designed with a large administrative sector in mind, its ability to expose bureaucratic behavior to public scrutiny is impressive, and the Congress plays a vital role in this endeavor.
Abstract: Congressional oversight activity has increased dramatically since the early 1970s. Congressional committees now spend more of their time holding hearings to review the activities of federal agencies, and committee staff members are busy collecting information about what goes on during program implementation. This book examines the reasons behind the surprising growth of congressional oversight. Using original data collected for this project, Joel D. Aberbach documents the increase in oversight activity and links it to changes in the political environment. He explores the political purposes served by oversight, the techniques Congress uses to uncover information about the activities of the federal bureaucracy, and the reasons why topics get on the oversight agenda. He concludes that even though the U.S. government system was not designed with a large administrative sector in mind, its ability to expose bureaucratic behavior to public scrutiny is impressive, and the Congress plays a vital role in this endeavor.
286 citations
281 citations
TL;DR: The nature and extent of DNA sequence divergence between homologous proteincoding genes from Escherichia coli and Salmonella typhimurium have been examined and appear to be undergoing concerted evolution, i.e., there has been exchange between the loci subsequent to the divergence of the two species.
Abstract: The nature and extent of DNA sequence divergence between homologous protein-coding genes from Escherichia coli and Salmonella typhimurium have been examined The degree of divergence varies greatly among genes at both synonymous (silent) and nonsynonymous sites Much of the variation in silent substitution rates can be explained by natural selection on synonymous codon usage, varying in intensity with gene expression level Silent substitution rates also vary significantly with chromosomal location, with genes near oriC having lower divergence Certain genes have been examined in more detail In particular, the duplicate genes encoding elongation factor Tu, tufA and tufB, from S typhimurium have been compared to their E coli homologues As expected these very highly expressed genes have high codon usage bias and have diverged very little between the two species Interestingly, these genes, which are widely spaced on the bacterial chromosome, also appear to be undergoing concerted evolution, ie, there has been exchange between the loci subsequent to the divergence of the two species
222 citations
TL;DR: C 60 buckminsterfullerene exhibits a large ultrafast third-order nonlinear optical response and, in contrast to conjugated polymers, a dominant positive real part of the nonlinearity is found, 3 times larger than theimaginary component.
Abstract: ${\mathrm{C}}_{60}$Buckminsterfullerene exhibits a large ultrafast third-order nonlinear optical response. Degenerate four-wave-mixing measurements in ${\mathrm{C}}_{60}$-benzene solutions were performed using 50-psec pulses at 1.064 \ensuremath{\mu}m. The magnitude of the nonlinear susceptibility per ${\mathrm{C}}_{60}$ molecule is \ensuremath{\Vert}\ensuremath{\gamma}\ensuremath{\Vert}=1.5\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}42}$ ${\mathrm{m}}^{5}$ ${\mathrm{V}}^{\mathrm{\ensuremath{-}}2}$ and of the same size as that observed in polydiacetylene. In contrast to conjugated polymers, however, a dominant positive real part of the nonlinearity is found, 3 times larger than the imaginary component. The nonlinear response can be described within the model of a free electron in a spherical box, confirming the complete delocalization of electrons on the ${\mathrm{C}}_{60}$ molecule.
216 citations
TL;DR: This study demonstrates the complete absence of any activity for this enzyme in the brain of the three species examined, and demonstrates that the enzyme exists only in the cytoplasm of rat liver cells.
Abstract: 1. Conflicting reports exist as to the organ distribution of betaine-homocysteine methyltransferase (EC 2.1.1.5). It is important to establish its presence or absence in brain, since its substrate, betaine, has recently become established in the treatment of certain diseases involving this organ. 2. It remains unclear whether the reported success of this treatment results from the use of betaine to methylate homocysteine and produce methionine in situ in neural tissue, or whether the effect is secondary to these same reductions happening in other organs, such as the liver. The former would require the presence of betaine-homocysteine methyltransferase in neural tissue. 3. This study demonstrates the complete absence of any activity for this enzyme in the brain of the three species examined. The enzyme was found to be present in both the liver and kidney of man and pig, but only in the liver of the rat. 4. The only source of betaine in cells is via the oxidation of choline. Since the enzymes involved in this conversion have never been shown to exist anywhere other than the mitochondria, it has been assumed that the methyltransferase is also mitochondrial. In this study, it is demonstrated that the enzyme exists only in the cytoplasm of rat liver cells.
207 citations
TL;DR: Overall, these findings indicate that there is diminished 5-HT responsivity in the depressed state.
Abstract: OBJECTIVE Theoretically, d-fenfluramine should be a more selective serotonin (5-HT) challenge agent and has much greater clinical tolerance than the racemic compound that has previously been used. The authors' goal, therefore, was to look at 5-HT function in depression using the d isomer of fenfluramine as a probe. METHOD They evaluated central 5-HT function in 23 patients with DSM-III-R-diagnosed major depression and 16 healthy control subjects. The depressed group included 10 men and 13 women; four were outpatients, two attended a day hospital facility, and 17 were inpatients. Subjects were cannulated at 8:30 a.m. after an overnight fast. After baseline samples were drawn, 30 mg of d-fenfluramine was administered orally and blood samples were drawn over the following 5-hour period for prolactin and cortisol estimation. RESULTS The plasma prolactin responses of the depressed patients were significantly lower than those of the control subjects. This blunting was not related to the severity of the depression but was significantly related to the patients' levels of state anxiety. Cortisol responses as well as prolactin responses were impaired in depression. High baseline cortisol levels were correlated with the severity of depression and the presence of weight loss. CONCLUSIONS Overall, these findings indicate that there is diminished 5-HT responsivity in the depressed state.
190 citations
Book•
01 Aug 1991TL;DR: An introduction to computer vision illumination and fixturing sensors image acquisition and representation fundamentals of digital image processing image analysis the segmentation problem 2-D shape description and recognition 3-D object representations robot programming and robot vision bin picking trends and aspirations.
Abstract: An introduction to computer vision illumination and fixturing sensors image acquisition and representation fundamentals of digital image processing image analysis the segmentation problem 2-D shape description and recognition 3-D object representations robot programming and robot vision bin picking trends and aspirations.
178 citations
TL;DR: A highly sensitive novel method based on the polymerase chain reaction (PCR) was reported to assess mixed hematopoietic chimerism after allogeneic bone marrow transplantation, finding sudden increases in the proportions of recipient cells may be a prelude to graft rejection or relapse.
TL;DR: A large number of neurotransmitters have now been shown to reduce the amplitude and slow the activation kinetics of whole cell HVA ICa in a great diversity of neurons, and substantial evidence exists for mediation of this action by cAMP.
TL;DR: It is concluded that the most important single view of the data is the Map View: all other views must be cross-referred to this, and the software must encourage this.
Abstract: We explore the application of dynamic graphics to the exploratory analysis of spatial data. We introduce a number of new tools and illustrate their use with prototype software, developed at Trinity College, Dublin. These tools are used to examine local variability—anomalies—through plots of the data that display its marginal and multivariate distributions, through interactive smoothers, and through plots motivated by the spatial auto-covariance ideas implicit in the variogram. We regard these as alternative and linked views of the data. We conclude that the most important single view of the data is the Map View: All other views must be cross-referred to this, and the software must encourage this. The view can be enriched by overlaying on other pertinent spatial information. We draw attention to the possibilities of one-many linking, and to the use of line-objects to link pairs of data points. We draw attention to the parallels with work on Geographical Information Systems.
TL;DR: Carbides of composition R 2 Fe 17 C x (x ≈2; R = Y, Sm) are formed by reaction of a powder of the 2:17 parent alloy in a hydrocarbon gas (methane, acetylene, butane) at around 550°C as discussed by the authors.
TL;DR: In this paper, an unclad fiber was dipcoated with a thin layer of porous cladding within which a pH-sensitive dye was entrapped, and the performance of the pH sensor was reported and the potential of the technique for distributed and integrated optic sensing was discussed.
Abstract: The sol-gel process for low temperature fabrication of porous glass has been used to entrap chemically-sensitive dyes for optical sensor applications. Evanescent wave excitation was used to examine the behaviour of an unclad fibre which was dipcoated with a thin layer of porous cladding within which a pH-sensitive dye was entrapped. The performance of the pH sensor is reported and the potential of the technique for distributed and integrated optic sensing is discussed.<
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01 Jan 1991
TL;DR: An introduction to computer vision illumination and fixturing sensors image acquisition and representation fundamentals of digital image processing image analysis the segmentation problem 2-D shape description and recognition 3-D object representations robot programming and robot vision bin picking trends and aspirations.
Abstract: An introduction to computer vision illumination and fixturing sensors image acquisition and representation fundamentals of digital image processing image analysis the segmentation problem 2-D shape description and recognition 3-D object representations robot programming and robot vision bin picking trends and aspirations.
TL;DR: The simultaneous lowering of dietary Ca and elevation of cholecalciferol on low-P diets restored all variables to the levels for the control diet and induced a hypophosphataemia and a hypercalcaemia which was reflected in reduced tibia length and weight and in reduced Ca, P and magnesium contents of tibia.
Abstract: Male broiler chicks (1-d-old; Ross one) were given either a control diet containing recommended levels of phosphorus, calcium and cholecalciferol or experimental diets low in P and with variable levels of Ca (normal and low) and cholecalciferol (normal or high). The low-P diet with normal levels of Ca and cholecalciferol induced a hypophosphataemia and a hypercalcaemia which was reflected in reduced tibia length and weight and in reduced Ca, P and magnesium contents of tibia. The phytate digestibility remained normal while the retention of P and Ca fell significantly. The lowering of Ca alone elevated phytate digestibility and restored P and Ca retention. The hypercalcaemia and hypophosphataemia remained and tibia mineralization remained impaired. The raising of cholecalciferol alone dramatically increased phytate digestibility and the retention of Ca and P. While this remedied the hypercalcaemia, the hypophosphataemia persisted as did the diminution of tibia weight. The simultaneous lowering of dietary Ca and elevation of cholecalciferol on low-P diets restored all variables to the levels for the control diet. Circulating levels of 1,25-dihydroxycholecalciferol were significantly elevated by low-P diets, more so with high cholecalciferol intakes. However, Ca did not influence 1,25-dihydroxycholecalciferol levels in plasma.
TL;DR: The prolactin (PRL) response to fenfluramine (FEN), a serotonin (S‐HT) releasing agent, is used as an index of 5‐HT sensitivity in studying disorders associated with central S‐HT abnormality and an effect that oestradiol may exert at central serotonin sites is discussed.
Abstract: The prolactin (PRL) response to fenfluramine (FEN), a serotonin (5-HT) releasing agent, is used as an index of 5-HT sensitivity in studying disorders associated with central 5-HT abnormality. Plasma oestrogen levels are known to augment PRL responses to a variety of stimuli. In order to examine the effect that ovarian steroids have on this response nine, healthy women were tested twice at three time points in the menstrual cycle: early follicular, mid-cycle and late luteal phase with either d-FEN, a more specific 5-HT agent than the racemic mixture, or placebo. Responses to d-FEN were maximal at mid-cycle, lowest during the early follicular phase, with responses premenstrually being intermediate between the two. Responses to placebo did not vary. Plasma oestradiol levels fluctuated in parallel with neuroendocrine responses to d-FEN. The possible mechanisms are discussed, including an effect that oestradiol may exert at central serotonin sites.
TL;DR: The effects of low concentrations of ACPD have been studied on the induction of long-term potentiation (LTP) in the hippocampal slice.
TL;DR: In this article, the easy direction of magnetization of R2Fe17 compounds can be identified by analysis of the hyperfine field and quadrupole interactions, and the 6-order crystal-field parameter B66 determines the easy magnetization direction in the basal plane.
Abstract: 57Fe Mossbauer spectra have been obtained at room temperature and at 15 K for R2Fe17 and R2Fe17N3- delta ( delta approximately=0.4) with R identical to Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Lu and Y. The easy direction of magnetization of the R2Fe17 compounds can be identified by analysis of the hyperfine field and quadrupole interactions. For rare-earth elements with J>3, the sixth-order crystal-field parameter B66 determines the easy magnetization direction in the basal plane. In the nitrides, the average hyperfine field at 15 K increases by approximately 13% above the value in the parent compounds, from about 31 to 35 T, and it is anisotropic, being greatest when the magnetization lies along the c-axis. There is also an increase in the isomer shift of 0.12(2) mm s-1. Spin reorientation transitions occur in the nitrides of Er and Tm; only the samarium nitride has an easy c-axis at room temperature, but Sm, Er and Tm all have easy c-axis magnetic structures at 15 K.
TL;DR: Data provide direct evidence for an additional autosomal dominant RP locus and strongly implicate the human equivalent of the mouse retinal degeneration slow (rds) gene, peripherin-rds, as a candidate for autosome dominant retinitis pigmentosa.
TL;DR: The properties of S. aureus surface polysaccharides and proteins are reviewed and the possibility that they could be used as components of new vaccine to combat mastitis in ruminants and nosocomial infections is discussed.
TL;DR: Information is provided on how to identify the different components of the EMMARM, or “building blocks” that contribute to or detract from the development of EMT.
Abstract: INTRODUCTION . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 MUTATIONS AFFECTING NONPROGRAMMED FRAMESHIFTING . . . . . . . . . . . . . . . . . . 203 Is olation . . . . . . . .. . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 Occurrence and Conseq uences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .... . . . . . . . . . . . . . . . . .. . . . . . . . . 204 M utant tRNAs.. . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . 205 M utant Ribosomes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . 217 M utant Elongation and Te rmination Factors and Ne w Elongation Factorlike Ex te nde d Prote ins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1 8 M utati ons I ndi re ctly Affecti ng Translation . . . . . . . . . . . .... 220 MUTATIONS AFFECTING NATURAL PROGRAMMED FRAMESHIFTING . . . . . . . .. 221 SUMMARY AND OUTLOOK . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . 222
TL;DR: In this article, the optical spectroscopy of the europium ion has been used as a probe of the structure of sol-gel derived silica glasses, and changes in these optical properties were interpreted in terms of the constantly changing environment of the Eu3+ ion.
Abstract: The optical spectroscopy of the europium ion has been used as a probe of the structure of sol-gel derived silica glasses. The fluorescence and optical decay times of the Eu3+ ion were monitored during the different stages of the sol-gel process and changes in these optical properties were interpreted in terms of the constantly changing environment of the Eu3+ ion.
Journal Article•
TL;DR: The Felman & Peters (1979) geometrical equation takes account of these criteria and provides a method of estimating 'true' spine numbers which does not involve slow and laborious reconstruction and should be used when comparisons are being made between loci, cell types and species.
Abstract: Dendritic spines are small protrusions extending from the dendrites of nerve cells, which bear the majority of synapses. In the past, researchers quantified spine density as the number of visible spines per estimated micrometre of dendrite. This estimate ignores all those spines hidden from view due to their position on the dendrite. Dendrites vary in diameter and the underestimation in some will be greater than others. Estimation of dendritic length is also subjective and difficult in those which are tortuous. The Felman & Peters (1979) geometrical equation takes account of these criteria and provides a method of estimating 'true' spine numbers which does not involve slow and laborious reconstruction. This study compares ratios derived from both methods of estimation (spine density 2:1) at three loci in three experimental groups. Mean values of dendritic diameters and spine dimensions show the major cause for variation in the ratios between loci to be the shaft diameter of the dendrite. However, the greater ratio for apical as compared with basal and oblique dendrites is not as great as expected, bearing in mind that apical dendrites are approximately 2.5 times larger than oblique and basal dendrites. Therefore the spine distribution may not be the same throughout the dendritic field. Estimations of spine density based on visible spine counts are quicker, easier and sufficient for comparisons within the same locus. 'True' estimates (spine density 2) are more accurate and should be used when comparisons are being made between loci, cell types and species.
TL;DR: In this article, the authors present an analysis of all relevant palaeontological and global geological data strongly supports the notion that representatives of Silurian myodocope ostracods had pelagic lifestyles and habitats and that they may well be, within the Ostracoda, pioneer colonisers of such environments.
Abstract: . Analysis of all relevant palaeontological and global geological data strongly supports the notion that representatives of Silurian myodocope ostracods had pelagic lifestyles and habitats and that they may well be, within the Ostracoda, pioneer colonisers of such environments. Morphological evidence (from fossil and Recent myodocopes) combined with facies distributional and concomitant faunal evidence (from the Silurian of, for example, Britain, France, Czechoslovakia, Sardinia, Australia and China) endorses the idea that myodocope ostracods may have undergone a benthic to pelagic ecological shift during mid Silurian times. Lower Silurian myodocopes lived, with benthic associates, on well oxygenated shelves. Upper Silurian ostracods lived, typically with low diversity, largely pelagic faunas in outer shelf topographic lows or off-shelf basin slopes, and are characteristically associated with deposits which are in part suggestive of lowered oxygen levels or even anoxic conditions. A pre-adaptation for swimming may have allowed Silurian myodocopes to respond to environmental forcing (negative oxygen levels; positive trophic and nutrient incentives; rises in sea levels) by migrating, through time, up the water column.
TL;DR: In this article, the effects of rare-earth iron intermetallic compounds have been discussed with reference to three systems: R 2 Fe 17 N 3-δ, R 2Fe 17 C 3 -δ, and R(Fe 11 Ti)N 1-α.
TL;DR: Household garden soil was a potentially greater source of toxocara infection than soil in public parks and open spaces and none of the faecal specimens from pet dogs were positive for toxocar ova as compared to 6.2% of stray dogs.
Abstract: Toxocara canis antibody titres were measured in members of 30 families. 73/140 (52.1%) family members were seropositive for T. canis at a dilution greater than or equal to 1:50 and 11 (7.8%) had reciprocal titres greater than or equal to 800. Toxocara ova were sought (a) in relation to the 30 families and (b) in the community. No toxocara ova were found in household dust samples. 38% of family gardens contained toxocara ova while 6% of soil samples from public parks and open spaces around housing estates were positive. None of the faecal specimens from pet dogs were positive for toxocara ova as compared to 6.2% of stray dogs. 5.3% of canine faecal samples from the streets contained toxocara ova. In this study household garden soil was a potentially greater source of toxocara infection than soil in public parks and open spaces.
Book•
01 Jul 1991TL;DR: Findings indicate that integration of the φ13 genome into hlb is site‐and orientation‐specific, and that it is responsible for loss of βtoxin expression in Staphylococcus aureus.
Abstract: Lysogenization of Staphylococcus aureus by the serotype F converting bacteriophage phi 13 results in loss of beta-toxin expression. Sequence analysis of the S. aureus beta-toxin gene (hlb), the attachment site (attP)-containing region of phi 13 DNA and the chromosome/bacteriophage DNA junctions of a phi 13 lysogen, revealed that the molecular mechanism of loss of beta-toxin expression was due to insertion of the phi 13 genome into the 5' end of hlb. The insertion site (attB) within hlb contained a 14 base pair core sequence in common with attP and both ends of the integrated linear prophage genome of a phi 13 lysogen. These findings indicate that integration of the phi 13 genome into hlb is site- and orientation-specific.