Showing papers by "University of Aberdeen published in 1980"

Age-of-acquisition, imagery, concreteness, familiarity, and ambiguity measures for 1,944 words

Abstract: Age-of-acquisition, imagery, concreteness, familiarity, and ambiguity measures for 1,944 words of varying length and frequency of occurrence are presented. The words can all be used as nouns. Intergroup reliabilities are satisfactory on all attributes. Correlations with previous word lists are significant, and the intercorrelations between measures match previous findings.

Effects of changes in the structure of enkephalins and of narcotic analgesic drugs on their interactions with μ and δ-receptors

Abstract: 1 The activity pattern of analogues of the enkephalins was determined in four parallel assays, the inhibition of the electrically evoked contraction of the guinea-pig ileum and mouse vas deferens at 36 degrees C and the inhibition of [(3)H]-naltrexone and [(3)H]-leucine-enkephalin binding at 0 to 4 degrees C in homogenates of guinea-pig brain.2 The activity pattern was best characterized by the ratio of the potency in the guinea-pig ileum to that in the mouse vas deferens (G.p.i./M.v.d.) and the ratio of the potency in inhibiting [(3)H]-naltrexone binding to that in inhibiting [(3)H]-leucine-enkephalin binding (Nal/Leu).3 The enkephalins had low G.p.i./M.v.d. (0.02 to 0.09) and low Nal/Leu (0.05 to 0.18) ratios whereas the corresponding values for morphine were 7.0 and 7.5.4 Analogues obtained by substituting D-Ala for Gly(2) and D-Met or D-Leu for L-Met(5) or L-Leu(5) showed only minor changes in G.p.i./M.v.d. (0.01 to 0.11) and in Nal/Leu (0.06 to 0.13) ratios.5 Analogues in which resistance to enzymatic degradation was brought about by amidation of the C-terminal carboxylic group or methylation of the amino group of tyrosine or both modifications, had G.p.i./M.v.d. ratios of 1.2 to 5.5 and Nal/Leu ratios of 0.5 to 21. High values (2.1 and 3.4) were found for the potent antinociceptive analogue of Sandoz, Tyr-D-Ala-Gly-NCH(3)Phe-Met(O)-ol.6 In the mouse vas deferens, some of the analogues with high G.p.i./M.v.d. and Nal/Leu ratios were tested for antagonism by naloxone and found to require less than the high concentration needed for the natural enkephalins. C57/BL mice, which have a lowered sensitivity to morphine but a normal response to peptides with low G.p.i./M.v.d. and Nal/Leu ratios, had a lowered sensitivity to analogues with high ratios.7 In the alkaloid-like series of narcotic analgesic drugs, ketobemidone, levorphanol, methadone, etorphine and the antagonist Mr 2266 had lower Nal/Leu ratios (1.0 to 2.8) than morphine, normorphine, naloxone and naltrexone (8 to 12).8 It would appear that compounds with low G.p.i./M.v.d. and Nal/Leu ratios interact mainly with delta-receptors in the brain and peripheral nervous system while compounds with high ratios interact mainly with mu-receptors. For antinociceptive action mu-receptors may be more important than delta-receptors.

Hunters, Pastoralists and Ranchers: Reindeer Economies and their Transformations

Abstract: List of figures and tables Preface Prologue: on reindeer and men 1. Predation and protection 2. Taming, herding and breeding 3. Modes of production (1): hunting to pastoralism 4. Modes of production (2): pastoralism to ranching Epilogue: on band organization, leadership and ideology Appendix: the names and locations of circumboreal peoples Notes Bibliography Author index Subject index.

Mutants of Arabidopsis thaliana with altered responses to auxins and gravity

Abstract: Auxin-resistant mutants of Arabidopsis have been induced and isolated by screening for survivors on a medium containing the herbicide 2,4-D. Thirty independently arisen mutants have been isolated in this way and one of them, P 83, has been investigated in detail. When wild type and P 83 are compared in concentration/response curves, where the response is the inhibition of root growth, the ED50 values of the auxins, 2,4-D and IAA, are 14-fold higher for the mutant. The mutant also responds differently to gravity: its roots do not show positive geotropism, but tend to grow with a clockwise curvature on agar surfaces. The seedling roots of the mutant also grow more rapidly than those of the wild type in the absence of 2,4-D, following faster germination. The F1 between P 83 and wild type is similar to the latter, but has a slightly increased resistance to 2,4-D. Results obtained from the F2, F3 and backcross generations suggest monofactorial inheritance. Most of the other 29 mutants have the P 83 phenotype, but at least five are different. Four have lower levels of resistance to 2,4-D and P 83, and their roots appear to respond normally to gravity. One mutant has an abnormal georesponse and a much higher level of resistance to 2,4-D than P 83.

Activity patterns of Pipistrelle bats (Pipistrellus pipistrellus) in north-east Scotland

Abstract: Pipistrellus pipistrellus emerge from their nursery roosts in north-east Scotland about 35 minutes after sunset, at light intensities of between 15 and 35 lux. Cloud cover, windspeed, ambient temperature, rain, light mist and moonlight have no apparent effect on the time or pattern of emergence. Throughout pregnancy and lactation, emergence lasts for about an hour. After weaning, when the adult females have left the roost, their young take about 40 minutes to emerge. The average rate of initial emergence is proportional to colony size, and the maximum rate of emergence occurs half way through the exodus. During pregnancy in May and June most bats leave the roost once each night soon after dusk and return between midnight and dawn. After parturition in late June the activity pattern becomes bimodal and the numbers of bats outside the roost show peaks after dusk and immediately before dawn. There is intermittent activity in the vicinity of the roost all night and bats make two or three flights each night. After weaning in August the activity pattern gradually ceases to be bimodal, and the number of flights per bat falls to between one and two. The average time spent outside the roost varies between 2–5 and 5 hours during the summer. The recorded activity patterns of night-flying insects are all bimodal, with peaks after dusk and before dawn, corresponding with the maximum number of bats outside the roost during lactation.

A whole-body NMR imaging machine

Abstract: A nuclear magnetic resonance (NMR) machine capable of producing tomographic sections of the whole human body in vivo has been constructed. This system is based on a four coil, air-core electromagnet producing a field of 0.04 T which corresponds to a proton NMR frequency of 1.7 MHz. The images are produced line by line using a selective excitation technique. Magnetic field gradients up to about 5 mT/m are employed. Electronic subsystems are described here including a radiofrequency (RF) amplitude feedback circuit, an RF power amplifier, a transmit/receive switch, a receiver pre-amplifier and gradient coil drivers. For a single scan through a 103 mm3 sample of human muscle tissue in vivo, the measured proton density uncertainty is 24% and the spin-lattice relaxation time (T1) uncertainty is 74%. Phantom images using CuSO4 solution and in vivo sections through human chest, thighs and head are presented. T1 measurements of human muscle, liver and brain tissue in vivo give results which agree well with T1 values for corresponding rabbit tissues measured in vitro.

Comparison of the binding characteristics of tritiated opiates and opioid peptides.

Abstract: 1 Binding assays on homogenates of guinea-pig brain showed that the maximal number of binding sites was different tritiated ligands interacting with the opiate receptors. 2 At 25 degrees C the binding capacity of morphine or dihydromorphine was only about 3 pmol/g fresh brain whereas etorphine and D-Ala2-L-Leu5- and D-Ala2-L-Met5-enkephalin amide had capacities of 13 to 15 pmol/g brain. D-Ala2-D-Leu5-enkephalin had an intermediate capacity of about 6 pmol/g brain. 3 The binding capacities of the natural methionine- and leucine-enkephalins measured at 0 degrees C were 5 to 6 pmol/g brain. At this temperature, the binding capacity of dihydromorphine, D-Ala2-D-Leu5-enkephalin and of the two enkephalin amides was only slightly lower than at 25 degrees C. 4 In assays in which unlabelled ligand competed with the same labelled ligand, the inhibition constants (KI) were equal to or not more than twice as large as the equilibrium dissociation constant (KD) determined in saturation assays. In contrast, the KI of unlabelled dihydromorphine against [3H]-D-Ala2-D-Leu5-enkephalin or of unlabelled D-Ala2-D-Leu5-enkephalin against [3H]-dihydromorphine was about 20 times higher than the respective KD values. 5 When for a given compound the ratio of the KI value against [3H]-D-Ala2-D-Leu5-enkephalin to the KI value against [3H]-dihydromorphine (discrimination ratio) is calculated, a high value indicates selectivity in favour of the mu-receptor and a low value selectivity in favour of the delta-receptor. The most selective mu-agonist known so far is normorphine with a discrimination ratio of 70 and the most selective delta-agonist is D-Ala2-D-Leu5-enkephalin with a ratio of 0.11. The selectivity of the known antagonists is in favour of the mu-receptor, since their discrimination ratios are larger than 1, varying between 10 for naloxone and 4 for Mr 2266.

Characterization of opioid receptors in nervous tissue.

Abstract: The concept that endogenous opioid peptides interact with at least two different receptor sites developed from several experimental approaches. First, when the peptides were assayed by their effects on two pharmacological and two binding models, the rank order of activity differed in these four systems. Secondly, naloxone had a smaller antagonist effect on $\delta $-receptors in the mouse vas deferens than on its $\mu $-receptors. Thirdly, the enkephalins and morphine each occupied less than half of the total number of sites available in brain homogenates. Fourthly, cold ligands of the $\delta $-type protected the binding of tritiated $\delta $-agonists better than that of $\mu $-agonists, and vice versa. Finally, tritiated ethylketazocine binds to $\kappa $-receptor sites in homogenates of guinea-pig brain. It is readily displaced by etorphine, which binds uniformly to $\mu $-, $\delta $- and $\kappa $-receptors, but only by very high concentrations of $\mu $- or $\delta $-agonists. An interesting phenomenon is the potentiation of activity when an enkephalin analogue is conjugated to tobacco mosaic virus by the group of R. Schwyzer.

Opioid peptides and their receptors.

Abstract: The three agonists, methionine-enkephalin, leucine-enkephalin and beta-endorphin have different pharmacological patterns. It may be of particular importance that they vary in their relative affinities to the enkephalin and naltrexone binding sites in the brain; the former are probably related to delta-receptors prevalent in the mouse vas deferens and the later to mu-receptors prevalent in the guinea-pig. It is possible that mu-receptors are more important for the mediation of analgesic effects than delta-receptors. An understanding of the pharmacokinetics of the opioid peptides will be of basic importance for the design of enkephalin analogues suitable for use as analgesics in man.

Some effects of nickel toxicity on rye grass.

Abstract: Rye grass (Lolium perenne, cv.S-23) was grown for 4 weeks in a non-calcareous Seaton loam soil with varying amounts of Ni as NiSO4. The purpose of this investigation was to study the Ni toxicity and the relationship of Ni with other essential elements. Nickel depressed shoot yield at all levels except at the lowest levelviz 30 μg Ni/g soil. Nickel concentration of 50 μg/g in shoots did not reduce the dry matter production in rye grass although slight chlorosis did appear at this level. The Ni and Fe concentration of the shoots increased and that of Mn and Zn decreased with increasing rates of Ni application. Uptake of Mn and Zn decreased at all level of Ni. But Fe uptake showed a slight increase at the first two levels and a profound depression at the subsequent levels. The pattern of Ni uptake is different, being highest at the middle level and decreasing on both sides which showed that the increase of Ni concentration of shoots is not proportional to the reduction in the yield. The Ni−Fe ratio rather than Ni and Fe concentration in plants has shown better relationship with the toxic effects of Ni. The implications of Ni phytotoxicity are discussed with particular reference to serpentine soils.

The number of connected sparsely edged graphs. III. Asymptotic results

Abstract: The number of connected graphs on n labeled points and q lines (no loops, no multiple lines) is f(n,q). In the first paper of this series I showed how to find an (increasingly complicated) exact formula for f(n,n+k) for general n and successive k. The method would give an asymptotic approximation to f(n,n+k) for any fixed k as n ∞. Here I find this approximation when k = o(n1/3), a much more difficult matter. The problem of finding an approximation to f(n,q) when q > n + Cn1/3 and (2 q/n) - log n - ∞ is open.

Conduction and Dielectric Loss Mechanisms in β-Alumina and Glass: A Discussion Based on the Paired Interstitialcy Model

Abstract: A paired interstitialcy model is used as a basis for qualitative comparisons of conductivity and dielectric phenomena in β-alumina crystals and in glass. Thus, the increase in the conductivity of sodium silicate glasses with increasing Na2O activity can be explained if the concentration of (Na2*)2+ interstitial pairs increases with increased polarizability of O2- ions, expressed in terms of the optical basicity parameter, Δ. Similarly, the occurrence of the pronounced minima in conductivity isotherms (the mixed-alkali effect in glass) is attributed to disappearance of mobile interstitial pairs, e.g. (Li2*)2+ or (K2*)2+, and the stabilization (by polarization interactions) of apparently immobile mixed-alkali pairs, (LiK*)2+. The phenomenon of coionic conduction in certain β-alumina crystals is an interesting departure from this general pattern. The orientation dependence of the electrical modulus spectrum of monocrys-talline β-alumina highlights the presence of a bimodal distribution of relaxation times, in which the low-frequency component (v0=1011 Hz) may arise from the rearrangement of interstitial pairs and the high-frequency component (v0=2×1012 Hz) may arise from less hindered ionic motions. It is suggested that the motions of interstitial pairs and surrounding cations are mutually catalytic and that some form of combined motion is responsible for both the electrical and mechanical relaxations in β-alumina and glass.

The Use of a New Tilting Tunnel Respirometer to Investigate Some Aspects of Metabolism and Swimming Activity of the Plaice (Pleuronectes Platessa L.)

Abstract: 1.Plaice and other flatfish can be induced to swim down a slope of about 60° against an upwelling water flow in a water tunnel. 2. A tilting Brett-type tunnel respirometer based on the above principle enabled laboratory experiments on swimming plaice to be carried out. 3. From trials at 5°, 10°, 15 °C, the relationship between specific swimming speed, V (body lengths s −1 ), oxygen consumption, R (mg −1 . kg −1 h −1 ) and temperature, T is: log 10 = 0.3318 V + log 10 (2.45 T +26.52). 4. If the fish is resting (i.e. V = 0), the oxygen consumption is lower than predicted by the above equation. At rest: R = 3.14 T +2.66. 5. The cost of swimming in plaice is very similar to that of typical round fish such as haddock but the resting metabolic rate is lower than for haddock. 6. Before swimming, a negatively buoyant fish such as plaice must lift off the bottom. This cost of lift-off or posture effect makes it uneconomical for plaice to swim at speeds below 0.6 V .

Ionic conductivity and the weak electrolyte theory of glass

Abstract: Arguments are advanced in support of a weak electrolyte theory of glass which incorporates the paired interstitialcy mechanism recently proposed for s-alumina. The model can account for such heretofore unexplained phenomena as the temperature dependence of diffusion correlation factors, the mixed alkali effect and the anomalously large jump distances obtained from high-field conductivies.

Simple reaction times to the onset, onset, and contrast reversal of sinusoidal grating stimuli

Abstract: Response latencies to the onset, offset, and contrast reversal of sinusoidal gratings over a range of spatial frequencies were measured. For gratings of constant physical contrast, RT was monotonically related to spatial frequency regardless of presentation mode. Comparison of RTs to 1.0- and 9.0-cycle/deg gratings adjusted to equal apparent contrast showed that the RT shifts cannot be directly attributed to contrast sensitivity differences. It is concluded that spatial-frequency-dependent processing delays occur regardless of which temporal property of the stimulus the subject must respond to.

The Scent Marking Behaviour of the Brown Hyaena Hyaena Brunnea

Abstract: The deposition onto grass stalks of two distinct, strong-smelling substances produced in the anal scent pouch, is the most common form of scent marking in the brown hyaena (Hyaena brunnea). It is called pasting. The behaviour associated with pasting is described, as is the related functional anatomy of the scent pouch. The dispersion pattern of pastings within a group territory and the rate of marking in different parts of the territory were ascertained by direct observations on radio collared hyaenas. The data were analysed by the computer programs SYMAP and SYMVU which graphically display the data as a three dimensional map. Brown hyaenas leave most pastings in those areas in which they spend most time. This is in the central part of the territory. When they visit the boundaries, however, the frequency of pasting increases. GLC analyses of the pastings from two known individuals show distinct differences in the relative concentrations of the many compounds in the pastings of each. Behavioural observatio...

A comparative study of ordination techniques in numerical taxonomy in relation to racial variation in the ringed snake Natrix natrix (L.)

Abstract: The iniluence ot various types of standardization, similarity coefficient and ordination technique (i.e. non-metric multidimensional scaling, canonical analysis, principal coordinate analysis, Q_and R mode principal component analysis) are tested in relation to the numerical taxonomic analysis of the racial differentiation in the ringed snake, N. natrix. The a priori preferences and various criteria, including portrayal of a ‘known taxonomic model’, indicate that canonical analysis and R mode principal components analysis on column-standardized data (or its dual principal coordinate analysis) are to be recommended. Non-metric multidimensional scaling and lack of appropriate character standardization gave inferior results. SUMMARY Thirty-four numerical taxonomic analyses were run varying the method of data standardization, similarity coefficient and ordination technique (i.e. non-metric multidimensional scaling, canonical analysis, principal coordinate analysis and Q and R mode principal component analysis). These analyses were based on sample populations of both sexes representing the marked racial differentiation within the ringed snake N. natrix. Several a priori preferences are stated and various criteria are discussed for judging the taxonomic performance of the methods. (The methods are compared on the basis of taxonomic performance rather than empirical similarity.) On the basis of the a priori preferences, the similarity of the taxonomic conclusions (robustness) and how well they portrayed a ‘known taxonomic model’, the canonical analysis and principal component-coordinate analyses on data standardized by columns (characters) are to be preferred. The principal component/coordinate techniques on unstandardized data is not recommended neither is the use of non-metric multidimensional scaling.

Analytical Electron Microscopy of Cement Pastes: I, Tricalcium Silicate Pastes

Abstract: One hundred sixty-one particles of C-S-H from C3S pastes aged 1 to 180 days were analyzed. For pastes made from two C3S samples, the mean Ca:Si ratios were 1.52 and 1.61, respectively. The overall range of Ca:Si ratios was 1.21 to 1.96; most of the variation is considered to represent real differences in composition between individual particles. No significant correlations with curing time, degree of reaction, or morphological type of C-S-H were found.

The Economics of Tenure Choice: 1955-79

Abstract: The aggregate homeownership rate in the United States has continued to rise throughout the 1970s despite rising inflation and the rapid growth of young and primary individual households with relatively low homeownership rates. This appears to be a result of a decline in the cost of homeownership relative to renting. The post 1965 decline in the real after-tax interest rate has acted to reduce the costs of both types of housing. However, inflation, and legislation induced increases in taxation of rental housing have largely offset the decline in the net real financing rate. Depreciation is based on historic cost and nominal capital gains are taxed. Moreover, this taxation was increased in 1969 and 1976 with the introduction and expansion of the minimum tax, the increased recapture of accelerated depreciation, and the amortization, rather than expensing, of construction period interest and property taxes. The decline in the cost of owner-occupied housing relative to rental housing is estimated to have sharply increased homeownership. In the absence of this decline 4.5 to 5 million fewer households would have been homeowners at the end of 1978. That is, the homeownership rate would have been 60 percent, rather than 65 percent.