Showing papers by "University of Aberdeen published in 1989"
TL;DR: The chapter describes the basic features of the biochemistry of ammonia and nitrite oxidation and discusses the growth limiting factors and activity of these organisms.
Abstract: Publisher Summary This chapter highlights the physiology of autotrophic ammonia- and nitrite-oxidizing bacteria. Several aspects of the physiology of nitrifiers of relevance to their growth and activity in natural environments are considered. The chapter describes the basic features of the biochemistry of ammonia and nitrite oxidation and discusses the growth limiting factors and activity of these organisms. The influence of oxygen concentration, pH value, and inhibitors on their physiology is also described. Nitrification plays a central role in the nitrogen cycle of terrestrial and aquatic ecosystems, converting the most reduced form of nitrogen, NH3, to the most oxidized form, NO3. Nitrifying bacteria occupy niches in many ecosystems and compete successfully with faster and more efficiently growing organisms for oxygen, ammonia, and carbon dioxide. Nitrifiers are capable of reversing the nitrification process, carrying out denitrification and producing nitrite, ammonia, nitrous and nitric oxides, and gaseous nitrogen. Ammonia oxidizers can metabolize urea and can assimilate carbon from methane while nitrite oxidizers can grow anaerobically in the presence of organic compounds and nitrate.
795 citations
TL;DR: This paper seeks to highlight some of the critical issues concerning the use of the Quality Adjusted Life Years to measure the outcome of health care choices, in decisions related to both individual patient care and social resource allocation.
388 citations
TL;DR: All measures of nerve capillary pathology correlated significantly with neurophysiological and neuropathological measures of neuropathic severity and there was no significant correlation between the duration of diabetes and HbA1 levels with capillaryPathology or with neuropathy severity.
Abstract: Clinical, electrophysiological and ultrastructural morphometric observations were made in 5 diabetic non-neuropathic patients, 5 diabetic patients with mild neuropathy and 11 diabetic patients with severe neuropathy. Capillary abnormalities were assessed in simultaneous nerve, muscle and skin biopsies and compared with results from 6 age-matched, non-diabetic control subjects. Nerve capillaries demonstrated markedly greater pathology than skin and muscle capillaries. Endoneurial capillary density was significantly reduced in severely neuropathic diabetic patients (p less than 0.01) when compared with control subjects. Capillary basement membrane (p less than 0.002), endothelial cell (p less than 0.003) and total diffusion barrier (endothelial cell, pericyte, basement membrane) (p less than 0.001) thickness were significantly increased, and oxygen diffusing capacity was significantly reduced (p less than 0.001) in the nerves of patients with severe diabetic neuropathy when compared to control subjects. Endothelial cell profile number and luminal perimeter were significantly increased in asymptomatic (p less than 0.01), (p less than 0.05) and severely neuropathic (p less than 0.001), (p less than 0.05) diabetic patients respectively. However, endothelial cell outer perimeter, a measure of capillary size, showed no significant increase in diabetic patients when compared with control subjects. An association was observed between neurophysiological and neuropathological measures of neuropathic severity. There was no significant correlation between the duration of diabetes and HbA1 levels with capillary pathology or with neuropathic severity. Very few abnormalities of muscle and skin correlated with neuropathic severity. However, all measures of nerve capillary pathology correlated significantly with neurophysiological and neuropathological measures of neuropathic severity.
262 citations
TL;DR: Serum lipid peroxide concentrations and enzyme activities were increased after exercise, and subjects with the greatest increase in CK, LDH, and AST also showed the highest serum TBARS concentration, suggesting a possible relationship between free radical generation and exercise‐induced muscle damage.
Abstract: Lipid peroxidation initiated by free radical reactions is associated with tissue necrosis in a variety of conditions. We have measured serum lipid peroxide concentrations (as total thiobarbituric acid-reactive substances, TBARS) and creatine kinase (CK), lactate dehydrogenase (LDH), and aspartate aminotransferase (AST) activities and subjective muscle soreness in 16 men before and after a 45-minute downhill treadmill run. TBARS concentrations and enzyme activities were increased after exercise, with peak values observed at 6 hours (TBARS, LDH) or 24 hours (CK, AST) after exercise. Serum LDH activity returned to preexercise levels by 48 hours after exercise and TBARS by 72 hours after exercise: CK and AST activities remained elevated 72 hours after exercise. Leg muscle soreness also increased, with the greatest degree of soreness seen at 24 or 48 hours after exercise. Subjects with the greatest increase in CK, LDH, and AST also showed the highest serum TBARS concentration. This suggests a possible relationship between free radical generation and exercise-induced muscle damage.
212 citations
TL;DR: In this article, regression equations for predicting Wechsler Adult Intelligence Scale (WAIS) IQ from performance on the National Adult Reading Test (NART) were used to predict 66, 72 and 33 per cent of the variance in WAIS Full Scale, Verbal and Performance IQ respectively.
Abstract: Nelson (1982) presented regression equations for the prediction of Wechsler Adult Intelligence Scale (WAIS) IQ from performance on the National Adult Reading Test (NART). In a cross-validation sample (n = 151) these equations predicted 66, 72 and 33 per cent of the variance in WAIS Full Scale, Verbal and Performance IQ respectively. There were no ceiling or floor effects in the relationship between NART performance and WAIS IQ despite the wide IQ range of the sample. The standardization and cross-validation samples were combined (n = 271) to generate new regression equations. These equations should be used in preference to the original equations as they are based on a larger sample with a wider IQ and age range. Combining NART and Schonell Graded Word Reading Test errors did not improve IQ prediction in poor readers. A detailed examination of the NART's test—retest and inter-rater reliability was also conducted.
192 citations
TL;DR: In this article, the long run relationship between nominal interest rates and inflation using cointegration techniques was tested using co-integration technique. But the results were limited to the first half of 1989.
Abstract: (1989). Testing for the long run relationship between nominal interest rates and inflation using cointegration techniques. Applied Economics: Vol. 21, No. 4, pp. 439-447.
179 citations
TL;DR: The immunological properties of FK-506 are reviewed, its potential in the light of the impact already made by CsA is assessed and its two agents can act synergistically both in vivo and in vitro.
164 citations
TL;DR: This article reviewed the adaptations of order in brain membranes of those fish which acclimate to seasonal changes in temperature or which have evolved in extreme thermal or abyssal habitats and found that fish from extreme cold environments with those from temperate or tropical waters reveal a more complete adaptation.
Abstract: The homoeostatic regulation of bilayer order is a property of functional importance. Arguably, it is best studied in those organisms which experience and must overcome disturbances in bilayer order which may be imposed by variations in temperature of hydrostatic pressure. This article reviews our recent work on the adaptations of order in brain membranes of those fish which acclimate to seasonal changes in temperature or which have evolved in extreme thermal or abyssal habitats. The effects of temperature and pressure upon hydrocarbon order and phase state are reviewed to indicate the magnitude of the disturbances experienced by animals in their environments over the seasonal or evolutionary timescale. Acclimation of fish to altered temperature leads to a partial correction of order, while comparison of fish from extreme cold environments with those from temperate or tropical waters reveals a more complete adaptation. Fish from the deep sea also display adaptations of bilayer order which largely overcome the ordering effects of pressure.
145 citations
TL;DR: What is known of the biology of these important pathogens of farmed Atlantic salmon is presented and the shortcomings of this knowledge are highlighted in terms of useful insights which could lead to more effective control measures.
138 citations
TL;DR: In this article, the authors examine the contribution of cross-cultural studies to our understanding of the perception and representation of space and show that different cultures use different skills to perform the same perceptual tasks.
Abstract: This paper examines the contribution of cross-cultural studies to our understanding of the perception and representation of space. A cross-cultural survey of the basic difficulties in understanding pictures—ranging from the failure to recognise a picture as a representation to the inability to recognise the object represented in the picture— indicates that similar difficulties occur in pictorial and nonpictorial cultrues. The experimental work on pictorial space derives from two distinct traditions: the study of picture perception in “remote” populations and the study of the perceptual illusions. A comprison of the findings on pictorial space perception with those on real space perceptual illusions. A comparison of findings on pictorial space perception with those on real space perception and perceptual constancy suggersts that cross-cultural differences in the perception of both real and representational space involve two different types of skills: those related exclusively to either real space or representational space, and those related to both. Different cultural groups use different skills to perform the same perceptual tasks.
137 citations
TL;DR: Results indicated no significant differences on all AVLT measures of learning, recall, and recognition, suggesting that the parallel version can be used as an equivalent form of the AVLT.
Abstract: The purposes of the present study were (1) to investigate whether significant savings occur with repeat testing on Rey's Auditory-Verbal Learning Test and (2) to develop a parallel version of the AVLT. Subjects (N = 60) were divided into pairs (individually matched for sex, age, and education) to form two groups and were administered either the AVLT or a parallel version. Results indicated no significant differences on all AVLT measures of learning, recall, and recognition, suggesting that the parallel version can be used as an equivalent form of the AVLT. Subjects were retested after an interval of 27 (+/- 3) days, with half receiving the same version and half receiving a different version. In contrast to subjects receiving different lists, those who were retested with the same version demonstrated a significant improvement in performance on the majority of AVLT variables.
TL;DR: With good surgical procedure, intraperitoneal implantation appears to provide a suitable technique for attaching transmitters to fish, and may be preferable to existing methods for many fish.
Abstract: For the first time, workers in the U.K. with a Home Office licence may surgically implant transmitters into wild fish in order to track them. A laboratory study was designed to investigate the effects of intraperitoneally implanted transmitters on rainbow trout. No significant difference in mortality or growth occurred between control, sham-implanted and implanted groups of fish over a 7-month period. Transmitters became encapsulated by connective tissue, the composition of which is described. Three fish expelled transmitters via the body wall without subsequent mortality or morbidity. Histological evidence suggests pressure necrosis of the body wall adjacent to the tag to be the mechanism of expulsion. With good surgical procedure, intraperitoneal implantation appears to provide a suitable technique for attaching transmitters to fish, and may be preferable to existing methods for many fish.
TL;DR: This article examined the implication of the cointegration literature for the efficiency of foreign exchange markets and showed that if currency markets are efficient, then two spot exchange rates cannot be cointegrated.
TL;DR: In this article, the characteristic properties of vitreous electrolytes are summarised for convenience under the three headings of continuity, variability and vulnerability, which cover respectively the tempe, stability and vulnerability.
Abstract: The characteristic properties of vitreous electrolytes are summarised for convenience under the three headings of ‘continuity’, ‘variability’ and ‘vulnerability’. These cover respectively the tempe...
TL;DR: Two field experiments were carried out on an estuarine intertidal mudflat, enclosing varying densities of the crustacean predators Carcinus maenas and Crangon crangon, and there were significant effects on the size structure of the amphipod Corophium volutator.
Abstract: Two field experiments were carried out on an estuarine intertidal mudflat, enclosing varying densities of the crustacean predators Carcinus maenas and Crangon crangon. Effects of predation on prey densities were few and limited to cages with abnormally high densities of crabs. In both experiments there were significant effects on the size structure of the amphipod Corophium volutator. The results are compared with those from other caging experiments and it is suggested that, where marked, predation effects have been recorded unnaturally high densities of predators were used.
TL;DR: The results suggest that for the purpose of remediation in the algebra domain, when taught procedurally, “classical” computer-assisted instruction (CAI) would be as effective as an ITS.
TL;DR: Results support the model, previously based solely on genetic data, that Trk is a multisubunit complex and implicates the products of the other trk genes in the normal binding of TrkA to the complex in the cytoplasmic membrane.
TL;DR: Evidence is presented which suggests that, besides de novo glycine betaine uptake, an important function of ProU may be the recapture and recycling of other osmolytes that leak from the cell.
Abstract: Summary
The proU loci of Salmonella typhimurium and Escherichia coli encode high-affinity glycine betaine transport systems which play an important role in survival under osmotic stress. Transcription of the proU locus is tightly regulated by osmolarity and this regulation appears to be mediated by osmotically induced changes in DNA supercoiling. In order to study the regulatory mechanisms involved we have cloned and characterized the proU locus of S. typhimurium by an in vivo transductional procedure. The locus is shown to consist of at least three genes, designated proVWX, cotranscribed as a single operon. The first gene in the operon encodes a protein sharing considerable sequence identity with ATP-binding proteins from other periplasmic transport systems. Unexpectedly, the highly expressed periplasmic glycine betaine binding protein was found to be encoded by a distal gene, proX, in the operon. The operon has no significant internal promoters but is expressed from a single osmoregulated promoter whose transcription start site has been mapped. The proU promoter of E. coli has also been sequenced and the transcription start site shown to be similar to that of S. typhimurium. Evidence is presented which suggests that, besides de novo glycine betaine uptake, an important function of ProU may be the recapture and recycling of other osmolytes that leak from the cell.
TL;DR: It is concluded that vigilance in buffalo was not restricted to predator detection, and that in periods in which epidemics or drought conditions are absent it was normal that ultimately some 90% of the large herbivores fell victim to predation.
Abstract: 1. Aspects of the influence of predation on the African buffalo Syncerus caffer were studied in Lake Manyara National Park, northern Tanzania, from 1981 to 1985. 2. During the study period, predation by lions was the most important cause of death in buffalo but occasionally major epidemics, such as rinderpest, can be by far the most important cause of death. 3. A comparison of Manyara with four other areas in Africa shows that the Manyara buffalo ran the same level of risk as those in these other areas, and that in periods in which epidemics or drought conditions are absent it was normal that ultimately some 90% of the large herbivores fell victim to predation. 4. Juvenile mortality in females was higher than in males but adult mortality in females was lower than in males. Adult bulls ran a much higher risk to be killed by lions (12.9% p.a.) than herd-living buffalo (4.4% p.a.); the latter category comprised cows and sub-adult bulls. 5. Risk of predation was highest near the ecotone between grasslands and structurally closed vegetations. Grasslands were as dangerous as woodlands and thickets, and only the mudflats were really safe. The chance to be killed fell steeply away from (potential) cover for lions. 6. Buffalo were more vigilant at night than during the day, peripheral animals more so than central ones. Adult bulls were more vigilant than other categories of buffalo. It is concluded that vigilance in buffalo was not restricted to predator detection. 7. The choice of feeding areas in buffalo was not dictated by predation risk alone.
TL;DR: In this paper, the authors compared two part-task training regimes with a control training regime basd on whole-task practice, and found that the latter was superior to the former.
TL;DR: Bleeding in promyelocytic leukaemia may be primarily a fibrinolytic disorder, characterized by free u‐PA in the plasma and differed from that seen after classical defibrination, where free t‐PA was observed.
Abstract: Summary. Three consecutive patients with acute promyelocytic leukaemia who presented with severe haemorrhagic syndromes were studied and the findings contrasted with those of two patients with classical defibrination after electroshock or complicated labour. The leukaemic patients showed no depletion of fibrinogen. There was no evidence of disordered thrombin generation by either intrinsic or extrinsic pathway sufficient to account for their haemorrhage. All, however, showed strikingly enhanced fibrinolytic activity, which could have accounted for bleeding. This fibrinolytic disorder was characterized by free u-PA in the plasma and differed from that seen after classical defibrination, where free t-PA was observed. U-PA was found also in malignant promyelocytes, which may be the source of u-PA activity in the patients' plasma. Bleeding in promyelocytic leukaemia may be primarily a fibrinolytic disorder.
TL;DR: The velocities with which grains were observed to emerge from a sand bed after an intersaltation collision at u* = 40 cm s−1 are reported for four bed attitudes, from horizontal bed to adverse bed slope 15° as mentioned in this paper.
Abstract: The velocities with which grains were observed to emerge from a sand bed after an intersaltation collision at u* = 40 cm s−1 are reported for four bed attitudes, from horizontal bed to adverse bed slope 15°. The principal effect of bed angle is to alter the magnitude and direction of the ricochet velocity. However, emergent velocities of dislodged grains are consistent with reptation path lengths comparable to the length of the upwind face of ripples in the corresponding wind.
Calculations of the loss of forward momentum at collision, using the data for the range of bed attitudes studied suggest that creep is most vigorous on the sloping upwind face of the ripple and diminishes at the crest. As a result, the crest would be expected to accumulate the coarse material which moves predominantly by creep.
The saltations originating in ricochet from the sloping back of the ripple are more vigorous and more concentrated in plan than are those originating at the crest. However, the saltation path length is at least an order of magnitude greater than the ripple wavelength and the probability distribution of path lengths is quite dispersed. Consequently it is very unlikely that these spatial patterns of ricochet are preserved sufficiently distinctly in the saltation cloud and subsequent collision distribution to be the agent of ripple development.
This study therefore supports a view of moving grain interaction with the bed in which saltation provides the power to mobilize grains but ripple growth is associated with reptation and particularly with a pattern of impact which develops with the bed relief. Creep is more active on upwind facing slopes than at the crest, which therefore is a zone of net creep grain deposition.
TL;DR: The results indicate the potential of the ac-impedance technique for probing the electrical properties of ferroelectric materials; some of the disadvantages associated with using fixed-frequency dielectric loss measurements are discussed.
Abstract: ${\mathrm{LiTaO}}_{3}$ is both a modest conductor of ${\mathrm{Li}}^{+}$ ions and electrons at high temperatures and a ferroelectric. From ac-impedance data recorded over a wide temperature (500--700 \ifmmode^\circ\else\textdegree\fi{}C) and frequency (30 mHz--1 MHz) range, it was possible to measure the following with the crystal c axis oriented parallel to the electric field: the charge polarization associated with the ferroelectric domains, the intrinsic polarization---which is high but not ferroelectric---of the crystal structure, the resistance associated with domain reorientation, and the resistance due to lithium-ion migration. The correct choice of equivalent circuit is crucial to the determination of these parameters. With the crystal c axis oriented perpendicular to the electric field, a much simpler response was seen. The capacitance values are small, have very little temperature dependence, and show no signs of ferroelectricity. Also the crystal is a modest electronic conductor at high temperatures, 500--700 \ifmmode^\circ\else\textdegree\fi{}C, in this orientation. These results indicate the potential of the ac-impedance technique for probing the electrical properties of ferroelectric materials; some of the disadvantages associated with using fixed-frequency dielectric loss measurements are discussed.
TL;DR: In this paper, a terrestrial record of postglacial environmental change from a largely oceanic zone of the Earth is used to interpret this record, which is representative of the southern westerlies and provides a link between Antarctica and the temperate zones of southern South America.
TL;DR: Part of the slowing effect of diabetes may be related to a histochemically demonstrable loss of fast oxidative glycolytic fibres in soleus, particularly of the relaxation phase.
Abstract: Contractile and histochemical properties of soleus (a slow-twitch muscle) and extensor digitorum longus (EDL, a fast-twitch muscle) were studied in mature rats after 3 months of streptozotocin-induced diabetes. Results were compared with age- and weight-matched controls. Diabetes produced profound wasting of fast muscles and particularly of the fast glycolytic (FG) fibres. Slow muscle fibres, both within the mixed EDL and in soleus, were less atrophied. Strength performance of EDL was reduced by diabetes, but maintained in soleus. Diabetes was without effect on the time to peak tension (TTP) and half-relaxation time (HRT) of EDL. However it produced profound slowing of soleus muscles, particularly of the relaxation phase. Part of the slowing effect of diabetes may be related to a histochemically demonstrable loss of fast oxidative glycolytic (FOG) fibres in soleus. Histochemical staining for the oxidative marker succinic dehydrogenase (SDH) revealed marked disruption of reaction product distribution in soleus, indicating an impairment of oxidative capacity.
TL;DR: In this article, the authors presented the first results of an extension of PEDRI which uses magnetic field cycling, allowing larger samples to be imaged with lower levels of applied radiofrequency power.
01 Jan 1989-Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology
TL;DR: The extremely high auditory sensitivity shown by the audiogram and the directionality of hearing are discussed in terms of the adaptation of the auditory system to low frequencies and the role of a large pinna inP.
Abstract: 1.
The neural audiogram of the common long-eared bat,Plecotus auritus was recorded from the inferior colliculus (IC). The most sensitive best frequency (BF) thresholds for single neurones are below 0 dB SPL between 7–20 kHz, reaching a best value of -20 dB SPL between 12–20 kHz. The lower and upper limits of hearing occur at 3 kHz and 63 kHz, respectively, based on BF thresholds at 80 dB SPL. BF threshold sensitivities are about 10 dB SPL between 25–50 kHz, corresponding to the energy band of the sonar pulse (26–78 kHz). The tonotopic organization of the central nucleus of the IC (ICC) reveals that neurones with BFs below 20 kHz are disproportionately represented, occupying about 30% of ICC volume, occurring in the more rostral and lateral regions of the nucleus.
2.
The acoustical gain of the external ear reaches a peak of about 20 dB between 8–20 kHz. The gain of the pinna increases rapidly above 4 kHz, to a peak of about 15 dB at 7–12 kHz. The pinna gain curve is similar to that of a simple, finite length acoustic horn; expected horn gain is calculated from the average dimensions of the pinna.
3.
The directional properties of the external ear are based on sound diffraction by the pinna mouth, which, to a first approximation, is equivalent to an elliptical opening due to the elongated shape of the pinna. The spatial receptive field properties for IC neurones are related to the directional properties of the pinna. The position of the acoustic axis of the pinna and the best position (BP) of spatial receptive fields are both about 25° from the midline between 8–30 kHz but approach the midline to 8° at 45 kHz. In elevation, the acoustic axis and the BP of receptive fields move upwards by 20° between 9–25 kHz, remaining stationary for frequencies up to 60 kHz.
4.
The extremely high auditory sensitivity shown by the audiogram and the directionality of hearing are discussed in terms of the adaptation of the auditory system to low frequencies and the role of a large pinna inP. auritus. The functional significance of low frequency hearing inP. auritus is discussed in relation to hunting for prey by listening and is compared to other gleaning species.
TL;DR: Increased protein ration resulted in a linear increase in protein synthesis and protein degradation in cod; for each gram of protein eaten per fish per day, 1 g of protein was synthesised and 0.36 g of that protein was retained as growth.
TL;DR: Observed developmental trends in both legal vocabulary and conceptual appreciation of criminal law replicates previous work from Australia and America and supports the contention that children younger than 10 years are not well informed about the legal system.
Abstract: This paper describes a study of children's legal vocabulary and their knowledge of criminal court procedures. Subjects (aged six, eight, 10 years and adults) were also asked about their feelings regarding a hypothetical court appearance as a witness. All subjects, children and adults, performed best on a vocabulary recognition section, with descriptions and concepts proving more difficult. Observed developmental trends in both legal vocabulary and conceptual appreciation of criminal law replicates previous work from Australia and America and supports the contention that children younger than 10 years are not well informed about the legal system. Results indicated clear deficits in knowledge as well as frequent misconceptions regarding legal personnel and procedures.