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Showing papers by "University of St Andrews published in 1994"


Journal ArticleDOI
11 Nov 1994-Science
TL;DR: Glial cell line-derived neurotrophic factor (GDNF), originally identified as a trophic factor specific for dopaminergic neurons, was found to be 75-fold more potent than the neurotrophins in supporting the survival of purified embryonic rat motoneurons in culture and to be a good candidate for treatment of motoneuron disease.
Abstract: For survival, embryonic motoneurons in vertebrates depend on as yet undefined neurotrophic factors present in the limb bud. Members of the neurotrophin family are currently the best candidates for such neurotrophic factors, but inactivation of their receptor genes leads to only partial loss of motoneurons, which suggests that other factors are involved. Glial cell line-derived neurotrophic factor (GDNF), originally identified as a trophic factor specific for dopaminergic neurons, was found to be 75-fold more potent than the neurotrophins in supporting the survival of purified embryonic rat motoneurons in culture. GDNF messenger RNA was found in the immediate vicinity of motoneurons during the period of cell death in development. In vivo, GDNF rescues and prevents the atrophy of facial motoneurons that have been deprived of target-derived survival factors by axotomy. GDNF may therefore be a physiological trophic factor for spinal motoneurons. Its potency and specificity in vitro and in vivo also make it a good candidate for treatment of motoneuron disease.

1,323 citations


Journal ArticleDOI

1,269 citations


Journal ArticleDOI
17 Mar 1994-Nature
TL;DR: The finding that highly attractive facial configurations are not average shows that preferences could exert a directional selection pressure on the evolution of human face shape.
Abstract: The finding that photographic and digital composites (blends) of faces are considered to be attractive has led to the claim that attractiveness is averageness. This would encourage stabilizing selection, favouring phenotypes with an average facial structure. The 'averageness hypothesis' would account for the low distinctiveness of attractive faces but is difficult to reconcile with the finding that some facial measurements correlate with attractiveness. An average face shape is attractive but may not be optimally attractive. Human preferences may exert directional selection pressures, as with the phenomena of optimal outbreeding and sexual selection for extreme characteristics. Using composite faces, we show here that, contrary to the averageness hypothesis, the mean shape of a set of attractive faces is preferred to the mean shape of the sample from which the faces were selected. In addition, attractive composites can be made more attractive by exaggerating the shape differences from the sample mean. Japanese and caucasian observers showed the same direction of preferences for the same facial composites, suggesting that aesthetic judgements of face shape are similar across different cultural backgrounds. Our finding that highly attractive facial configurations are not average shows that preferences could exert a directional selection pressure on the evolution of human face shape.

773 citations


Journal ArticleDOI
TL;DR: A chronological account of the effects of members of the NGF family of neurotrophins on cells of the neural lineage with special reference to the peripheral nervous system is provided.
Abstract: Neurotrophins were originally identified by their ability to promote the survival of developing neurons. However, recent work on these proteins indicates that they may also influence the proliferation and differentiation of neuron progenitor cells and regulate several differentiated traits of neurons throughout life. Moreover, the effects of neurotrophins on survival have turned out to be more complex than originally thought. Some neurons switch their survival requirements from one set of neurotrophins to another during development, and several neurotrophins may be involved in regulating the survival of a population of neurons at any one time. Much of our understanding of the developmental physiology of neurotrophins has come from studying neurons of the peripheral nervous system. Because these neurons and their progenitors are segregated into anatomically discrete sites, it has been possible to obtain these cells for in vitro experimental studies from the earliest stage of their development. The recent generation of mice having null mutations in the neurotrophin and neurotrophin receptor genes has opened up an unparalleled opportunity to assess the physiological relevance of the wealth of data obtained from these in vitro studies. Here I provide a chronological account of the effects of members of the NGF family of neurotrophins on cells of the neural lineage with special reference to the peripheral nervous system.

480 citations


Journal ArticleDOI
TL;DR: The cell responses provide direct evidence for neural mechanisms computing form from nonrigid motion and the selectivity of the cells was for body view, specific direction, and specific type of body motion presented by moving light displays and is not predicted by many current computational approaches to the extraction of form from motion.
Abstract: Cells have been found in the superior temporal polysensory area (STPa) of the macaque temporal cortex that are selectively responsive to the sight of particular whole body movements (e.g., walking) under normal lighting. These cells typically discriminate the direction of walking and the view of the body (e.g., left profile walking left). We investigated the extent to which these cells are responsive under “biological motion” conditions where the form of the body is defined only by the movement of light patches attached to the points of limb articulation. One-third of the cells (25/72) selective for the form and motion of walking bodies showed sensitivity to the moving light displays. Seven of these cells showed only partial sensitivity to form from motion, in so far as the cells responded more to moving light displays than to moving controls but failed to discriminate body view. These seven cells exhibited directional selectivity. Eighteen cells showed statistical discrimination for both direction of movement and body view under biological motion conditions. Most of these cells showed reduced responses to the impoverished moving light stimuli compared to full light conditions. The 18 cells were thus sensitive to detailed form information (body view) from the pattern of articulating motion. Cellular processing of the global pattern of articulation was indicated by the observations that none of these cells were found sensitive to movement of individual limbs and that jumbling the pattern of moving limbs reduced response magnitude. A further 10 cells were tested for sensitivity to moving light displays of whole body actions other than walking. Of these cells 5/10 showed selectivity for form displayed by biological motion stimuli that paralleled the selectivity under normal lighting conditions. The cell responses thus provide direct evidence for neural mechanisms computing form from nonrigid motion. The selectivity of the cells was for body view, specific direction, and specific type of body motion presented by moving light displays and is not predicted by many current computational approaches to the extraction of form from motion.

379 citations


Journal ArticleDOI
TL;DR: Contrary to influential models of object recognition, the results indicate view-specific processing both for the appearance of separate object components and for integration of information across components.
Abstract: We investigated the role that different component parts play in the neural encoding of the visual appearance of one complex object in the temporal cortex. Cells responsive to the sight of the entire human body (but no to control stimuli) were tested with two subregions (head alone with the body occluded from sight and the body alone with the head occluded). Forty-two percent (22 of 53) of cells responded to the whole body and to one of the two body regions tested separately: 72% (17 of 22) responding to the head and 28% (5 of 22) to the rest of the body. Forty-two percent (22 of 53) of cells responded independently to both regions of the body when tested in isolation. The remaining cells (17%, 9 of 53) were selective for the entire body and unresponsive to component parts. The majority of cells tested (90%, 35 of 39) were selective for perspective view (e.g., some cells respond optimally to the side view of the body, others to the back view). Comparable levels of view sensitivity were found for responses to the whole body and its parts. Results indicate (1) separate neuronal analysis of body parts and (2) extensive integration of information from different parts. Contrary to influential models of object recognition (Marr and Nishihara, 1978; Biederman, 1987), the results indicate view-specific processing both for the appearance of separate object components and for integration of information across components.

294 citations


Journal ArticleDOI
TL;DR: Neurons not only partly compensate for different target distances by extending axons more rapidly the further they have to grow, but possess an intrinsic clock that switches on dependence at the right time in accordance with the time it normally takes their axons to reach their targets.

238 citations


Journal ArticleDOI
TL;DR: In this paper, the C40 index and the RA index were used to describe the aggregate shape and roundness characteristics of glacially transported clasts in glacigenic deposits, and the results showed that these aggregate clast form gradients reflect changes in the relative proportions of actively and passively transported debris on the moraines rather than progressive modification of actively-transported clasts.

217 citations



Journal ArticleDOI
TL;DR: Using energy correlated photon pairs created in parametric down-conversion, the authors demonstrate two-photon interference effects in fiber interferometers separated by 4.3 km of optical fiber.
Abstract: Using energy correlated photon pairs created in parametric down-conversion we demonstrate two-photon interference effects in fiber interferometers separated by 4.3 km of optical fiber. The measured 86% interference visibilities confirm the purely quantum mechanical origin of these correlations.

188 citations


Journal ArticleDOI
TL;DR: Within the high EE group, relatives with marked emotional overinvolvement were similar to the lowEE group, with problems attributed to factors more external to and uncontrollable by the patient.

Journal ArticleDOI
TL;DR: A substantial decline in seagrass cover in Western Port over the past twenty years is inferred from data to have reduced epifaunal production by an estimated ≈ 2500 tonnes ash-free dry weight (AFDW) per year within the bay.

Journal ArticleDOI
TL;DR: In this paper, the authors calculate the multifractal spectrum of a random measure constructed using a statistically self-similar process and show that with probability one can obtain a decomposition analogous to that in the deterministic case, with the exponents given by the solution of an expectation equation.
Abstract: We calculate the multifractal spectrum of a random measure constructed using a statistically self-similar process. We show that with probability one there is a multifractal decomposition analogous to that in the deterministic self-similar case, with the exponents given by the solution of an expectation equation.

Journal ArticleDOI
TL;DR: In this article, the hypothesis that formal planning is not associated with better-than-average performance is tested on a sample of SMEs, controlled by sector, using a 5-year operating period.
Abstract: SUMMARY The majority of the literature on corporate performance in SMEs has indicated that the absence of formal strategic planning (or inadequacies in its process) can be directly linked with failure, while its presence can be linked to success (Bracker and Pearson, 1986; Stoner, 1983). However, other empirical evidence fails to find a relationship (Robinson and Pearce, 1983). These differences are due to methodological and theoretical problems facing research in this domain. This paper attempts to improve on both issues. The hypothesis that ‘formal planning is not associated with better-than-average performance’ is tested on a sample of SMEs, controlled by sector, using a 5-year operating period. Five measures of financial performance are utilized, including both the arithmetic and geometric measurements of central tendency as appropriate. Moreover, perceptions of CEOs, rather than the aggregation of scale-based measurements of organizational variables, are used to prescribe the measure of formality used in the analysis.

Journal ArticleDOI
TL;DR: Bumblebees are likely to be substantially more important as pollinators of raspberries than are honeybees, especially as rasp berries though moderately self‐fertile may exhibit metaxenia.
Abstract: . 1The behaviour and activity patterns of Apis mellifera and of five species of Bombus were analysed in relation to climatic variables and nectar quality on three varieties of unsprayed cultivated raspberry (Rubus idaeus) in eastern Scotland. 2Stages of floral morphology and reward were similar for the three varieties: young flowers offered both nectar and pollen, but medium and old flowers offered nectar only, in diminishing quantities. 3A wide range of insects visited raspberry flowers, but bees were dominant, bumblebees being responsible for about 60% of all visits and honeybees making up most of the remaining percentage. All bees had substantial pollen deposited on their bodies during visits, though few specifically collected it. 4Bombus spp. were found to favour young (receptive) flowers strongly, especially early in the morning when pollen was most abundant: whilst Apis visited unselectively. Bumblebees also foraged over substantially longer periods of the day, and in poorer weather, some being present at most times of observation; and they foraged more quickly in terms of flower visits per minute. 5Bombus carried more pollen on their bodies than Apis, and also deposited more pollen on raspberry stigmas, with B.lapidarius and B.terrestris being particularly effective and also being the most abundant species. All bumblebees also foraged over a longer range, moving between canes and rows more frequently than did honeybees. 6Bumblebees are therefore likely to be substantially more important as pollinators of raspberries than are honeybees, especially as raspberries though moderately self-fertile may exhibit metaxenia. Reasons why Bombus may be the preferred pollinator in most sites of raspberry cultivation are discussed, together with implications for present and future growers.

Journal ArticleDOI
TL;DR: Very pure optical helices have been generated in an argon ion laser of low Fresnel number as discussed by the authors, with continuous cophasal surface of helical form, clearly demonstrated by spiral interference fringes produced in a novel interferometric arrangement.

Journal ArticleDOI
TL;DR: The suppression and enhancement of the spontaneous emission of entangled photon pairs in parametric down-conversion using suitably placed external mirrors is demonstrated.
Abstract: We demonstrate the suppression and enhancement of the spontaneous emission of entangled photon pairs in parametric down-conversion using suitably placed external mirrors. The mirrors permit interference between two possible ways of creating the photon pair. In principle these mirrors can be placed at an arbitrarily large distance from the crystal. The effect is of first order in the intensity of the down-conversion radiation.

Journal ArticleDOI
TL;DR: By reviewing the literature, the pedunculopontine tegmental nucleus seems to be involved in attentional and possibly also in learning processes, and could be mediated by influencing cortical function via the thalamus, basal forebrain and basal ganglia.

Journal ArticleDOI
TL;DR: Eight species of Brazilian Myrtaceae were studied for their flowering phenology, pollination biology, breeding system and fruiting success; all species were bee-pollinated with pollen as the floral reward; flowers opened early in the morning and lasted one day; buzz-pollination was registered in three species.
Abstract: summary Eight species of Brazilian Myrtaceae were studied for their flowering phenology, pollination biology, breeding system and fruiting success: Eugenia dysenteries, Siphoneugena densiflora, Blepharocalyx salicifolius, Campomanesia pubeacens, C. velutina, Myrcia linearifolia, M. rhodosepala and Psidium firmum. Flowering strategies were mass-flowering and steady-state types, with two species showing a pulsed flowering. All species were bee-pollinated with pollen as the floral reward; flowers opened early in the morning and lasted one day; buzz-pollination was registered in three species. Pollinator-sharing of Bombus spp. bees occurred in the four savanna shrubs, pre-dawn pollination by Ptiluglossa sp. (Colletidae) was found in arboreal 5. densiflora and the remaining two trees had open pollination systems. The three forest species were markedly self-incompatible, and two of the savanna species were effectively so, whilst three savanna species showed self-compatibility.


Journal ArticleDOI
TL;DR: This article uses data published recently in this journal, to show how PCA can assist in their evaluation, and attempts to bridge the gap between the theory and the applications of PCA.

Journal ArticleDOI
TL;DR: Natural larval settlement on black Perspex settlement panels was analysed for two experiments conducted amongst epifaunal assemblages beneath pier pilings at Williamstown, Victoria and one experiment at Mornington, Victoria, in southeastern Australia and shows clearly the importance of repeating experimental analyses such as these at a given site and of undertaking experiments at different sites.

Journal ArticleDOI
TL;DR: A multiwavelength comb is obtained from Er(3+) - and Nd(3+)-doped fiber lasers by incorporation of a section of multimode optical fiber into an otherwise single-mode fiber ring cavity.
Abstract: A multiwavelength comb is obtained from Er(3+) - and Nd(3+)-doped fiber lasers by incorporation of a section of multimode optical fiber into an otherwise single-mode fiber ring cavity. This combination of fiber types acts as a wavelength-dependent filter in the laser through spatial mode beating between the LP(01) and LP(11) modes in the multimode fiber.

Journal ArticleDOI
TL;DR: In this article, the drift and exchange of sea scallop larvae (Placopecten magellanicus ) on Georges Bank is investigated by tracking particles in three-dimensional flow fields consisting of the semidiurnal tidal current and autumn mean circulation on realistic topography.
Abstract: The drift and exchange of sea scallop larvae ( Placopecten magellanicus ) on Georges Bank is investigated by tracking particles in three-dimensional flow fields consisting of the semidiurnal tidal current and autumn mean circulation on realistic topography. Three composite flow fields are considered, each forced by non-linear tidal current interactions, seasonal-mean density gradients and seasonal-mean wind stress. The around-bank flow rates are in approximate agreement with the observed residual gyre, while the cross-isobath currents in the flow fields are consistent with observations only in being generally weak. In most cases it is unclear whether the discrepancies arise from observational uncertainties or from model approximations. In the simulations the particles are given the behavior and planktonic period expected of sea scallop larvae. Particle starting positions correspond to the three major scallop aggregations: the Northeast Peak (NEP), the Southern Flank (SF), and the Great South Channel (GSC). Simulations are run to examine the sensitivity of the particle trajectories and settlement numbers to aspects of larval biology (vertical distribution, ascent and descent rates, search times, growth and mortality rates), and to various flow field components. The pattern and extent of larval exchange and settlement are most sensitive to the duration and depth of planktonic drift, gyre strength, weak cross-isobath flow, and mortality rate. The simulations indicate significant larval exchange among the three aggregations, with self-seeding possible for the GSC and NEP, and unlikely for the SF. Given the high retention of particles on Georges Bank as a whole (10–73% before mortality), Georges Bank scallops should be considered self-sustaining.

Journal ArticleDOI
TL;DR: Feedforward processing does not deny the possibility that top-down influences, although poorly understood, may play a role in nulling image aspects that are predictable in appearance and/or not the object of attention such that only features containing relevant discriminatory information are processed further.

Journal ArticleDOI
TL;DR: In this article, a wide variety of TCM practices are explored, and the first major finding is that TCM has come to be applied in process industries as well as in assembly industries, and multiple objectives of cost reduction, quality assurance, timely introduction of new products into the market, and product development to attract customers.

Journal ArticleDOI
TL;DR: A meta-analysis of 18 experiments within the published literature reporting visual evoked potential IHTT indicates a significant experiment-wise predominance of faster right-to-left IHTTs.

Journal ArticleDOI
TL;DR: Results indicate that pedunculopontine tegmental nucleus lesions disrupt an element of reward-related responding, but do not affect the production of locomotor activity, which highlights the unlikely existence of specific "locomotion-inducing" centres in the mesencephalon and implicates the pedunculatedopontal nucleus in the formation of stimulus-reward associations.

Journal ArticleDOI
TL;DR: The limitations in a patient with visual form agnosia's ability to use different kinds of pattern information to guide her hand rotation suggest that such information may need to be transmitted from the ventral visual stream to these parietal areas to enable the full range of prehensive acts in the intact individual.
Abstract: We have previously reported that a patient (DF) with visual form agnosia shows accurate guidance of hand and finger movements with respect to the size, orientation, and shape of the objects to which her movements are directed. Despite this, she is unable to indicate any knowledge about these object properties. In the present study, we investigated the extent to which DF is able to use visual shape or pattern to guide her hand movements. In the first experiment, we found that when presented with a stimulus aperture cut in the shape of the letter T, DF was able to guide a T-shaped form into it on about half of the trials, across a range of different stimulus orientations. On the remaining trials, her responses were almost always perpendicular to the correct Orientation. Thus, the visual information guiding the rotation of DF's hand appears to be limited to a single orientation. In other words, the visuomotor transformations mediating her hand rotation appear to be unable to combine the orientations of the stem and the top of the T, although they are sensitive to the orientation of the element(s) that comprise the T. In a second experiment, we examined her ability to use different sources of visual information to guide her hand rotation. In this experiment, DF was required to guide the leading edge of a hand-held card onto a rectangular target positioned at dHerent orientations on a flat surface. Here the orientation of her hand was determined primarily by the predominant orientation of the luminance edge elements present in the stimulus, rather than by information about orientation that was conveyed by nonluminance boundaries. Little evidence was found for an ability to use contour boundaries defined by Gestalt principles of grouping (good continuation or similarity) or “nonaccidental” image properties (colinearity) to guide her movements. We have argued elsewhere that the dorsal visual pathway from occipital to parietal cortex may underlie these preserved visuomotor skills in DF. If so, the limitations in her ability to use different kinds of “pattern” information to guide her hand rotation suggest that such information may need to be transmitted from the ventral visual stream to these parietal areas to enable the full range of prehensive acts in the intact individual.

Journal ArticleDOI
TL;DR: It is concluded that accurate line drawings of even highly familiar faces are poor at conveying identity, which indicates the difficulty in making judgments of identification based on piecemeal and sparse configural information.
Abstract: Three experiments are reported in which the role of facial distinctiveness in linedrawing representations of famous faces has been examined In the first subjects were asked to select their impressions of best likeness interactively from a continuous range of drawings generated in real-time On average, 42% of caricatures were considered to be the best likeness of famous individuals The distinctiveness of the target faces related by independent observers correlated with the degree of exaggeration faces received to produce an optimal likeness More distinctive faces required less caricaturing In the second experiment caricature levels chosen as best likenesses were investigated Caricatures of famous faces were recognised more quickly (by 36% of subjects) and more accurately (by 28%) than the true veridical drawings Thus caricature enhancement can improve recognition in terms of both speed and accuracy In the third experiment the role of distinctiveness and its interaction with external and internal facial features was investigated The external (outer) hairline present in the previous experiment was found to provide a powerful frame of reference for the perceptual assessment of individuals' appearances; estimations of best likeness without external features present were, on average, veridical It is concluded that accurate line drawings of even highly familiar faces are poor at conveying identity Distinctiveness enhancement improves their likeness and their recognisability Such caricatured drawings provide improved access to memories of famous faces, which lends strong support to models of human-face memory and processing based on norm-based coding When required to decide upon the veracity of line drawings based only upon internal features subjects were able to make accurate judgments of veridicality As well as validating the interaction approach to best-likeness judgments, this result further indicates the difficulty in making judgments of identification based on piecemeal and sparse configural information