Showing papers by "University of St Andrews published in 1985"

Visual cells in the temporal cortex sensitive to face view and gaze direction

Abstract: The direction of eye gaze and orientation of the face towards or away from another are important social signals for man and for macaque monkey. We have studied the effects of these signals in a region of the macaque temporal cortex where cells have been found to be responsive to the sight of faces. Of cells selectively responsive to the sight of the face or head but not to other objects (182 cells) 63% were sensitive to the orientation of the head. Different views of the head (full face, profile, back or top of the head, face rotated by 45 degrees up to the ceiling or down to the floor) maximally activated different classes of cell. All classes of cell, however, remained active as the preferred view was rotated isomorphically or was changed in size or distance. Isomorphic rotation by 90-180 degrees increased cell response latencies by 10-60 ms. Sensitivity to gaze direction was found for 64% of the cells tested that were tuned to head orientation. Eighteen cells most responsive to the full face preferred eye contact, while 18 cells tuned to the profile face preferred averted gaze. Sensitivity to gaze was thus compatible with, but could be independent of, sensitivity to head orientation. Results suggest that the recognition of one type of object may proceed via the independent high level analysis of several restricted views of the object (viewer-centred descriptions).

Numerical methods in quaternary pollen analysis

Abstract: The information preserved in the pollen-stratigraphical record is often so numerous and complex that analysis is difficult. This volume describes and reviews numerical methods that can assist in the analysis of Quaternary pollen data, and provides numerous examples to illustrate their use. -- AATA

The Effects of Semantic Priming and Word Repetition on Event‐Related Potentials

Abstract: Event-related potentials (ERPs) were recorded during the performance of a lexical decision task, in which a proportion of the words were either semantic associates or repetitions of the preceding word. Reaction times were faster to both the second member of associated pairs (targets) and repeated words, with the latter facilitatory effect being more than twice that of the former. ERPs to the semantic primes were more negative-going than those to targets. This difference peaked around 400–450 ms after stimulus onset. Comparison of unrepeated and repeated words revealed a larger and temporally more extended difference, with a similar scalp topography. The prime-target differences are interpreted as a further example of the sensitivity of the ‘N400’ component of the ERP to semantic relationships between words. The differences between the repetition and priming effects in ERPs are considered equivocal with respect to the view that the associated behavioural effects are caused by different cognitive mechanisms.

Dissociation between components of spatial memory in rats after recovery from the effects of retrohippocampal lesions.

Abstract: 1. A series of 4 experiments examined the performance of rats with retrohippocampal lesions on a spatial water-maze task. 2. The animals were trained to find and escape onto a hidden platform after swimming in a large pool of opaque water. The platform was invisible and could not be located using olfactory cues. Successful escape performance required the rats to develop strategies of approaching the correct location with reference solely to distal extramaze cues. 3. The lesions encompassed the entire rostro-caudal extent of the lateral and medial entorhinal cortex, and included parts of the pre- and para-subiculum, angular bundle and subiculum. Groups ECR 1 and 2 sustained only partial damage of the subiculum, while Group ECR+S sustained extensive damage. These groups were compared with sham-lesion and unoperated control groups. 4. In Expt 1A, a profound deficit in spatial localisation was found in groups ECR 1 and ECR+S, the rats receiving all training postoperatively. In Expt 1B, these two groups showed hyperactivity in an open-field. In Expt 2, extensive preoperative training caused a transitory saving in performance of the spatial task by group ECR 2, but comparisons with the groups of Expt 1A revealed no sustained improvement, except on one measure of performance in a post-training transfer test. All rats were then given (Expt 3) training on a cueing procedure using a visible platform. The spatial deficit disappeared but, on returning to the normal hidden platform procedure, it reappeared. Nevertheless, a final transfer test, during which the platform was removed from the apparatus, revealed a dissociation between two independent measures of performance: the rats with ECR lesions failed to search for the hidden platform but repeatedly crossed its correct location accurately during traverses of the entire pool. This partial recovery of performance was not (Expt 4) associated with any ability to discriminate between two locations in the pool. 5. The apparently selective recovery of aspects of spatial memory is discussed in relation to O'Keefe and Nadel's (1978) spatial mapping theory of hippocampal function. We propose a modification of the theory in terms of a dissociation between procedural and declarative sub-components of spatial memory. The declarative component is a flexible access system in which information is stored in a form independent of action. It is permanently lost after the lesion. The procedural component is “unmasked” by the retrohippocampal lesion giving rise to the partial recovery of spatial localisation performance.

From polis to madina: urban change in late antique and early islamic syria

Abstract: La civilisation urbaine qui, en Occident, s'est effondree sous les coups des invasions barbares, a continue a s'epanouir en Orient, mais en subissant des changements qui, en plusieurs siecles, transformerent la polis antique en madina islamique. Exemple de la Syrie.

Obtaining common pruned trees

Abstract: Given two or more dendrograms (rooted tree diagrams) based on the same set of objects, ways are presented of defining and obtaining common pruned trees. Bounds on the size of a largest common pruned tree are introduced, as is a categorization of objects according to whether they belong to all, some, or no largest common pruned trees. Also described is a procedure for regrafting pruned branches, yielding trees for which one can assess the reliability of the depicted relationships. The tree obtained by regrafting branches on to a largest common pruned tree is shown to contain all the classes present in the strict consensus tree. The theory is illustrated by application to two classifications of a set of forty-nine stratigraphical pollen spectra.

Lipid peroxidation products and antioxidant proteins in plasma and cerebrospinal fluid from multiple sclerosis patients.

Abstract: Lipid peroxidation (LPx) products were measured as thiobarbituric acid-reactive substances (TS) and lipid-soluble fluorescent pigments (FP) in both plasma and CSF from MS patients and controls. Although no significant changes were found in MS plasma, we report here for the first time increases in both TS and FP in MS CSF (p<0.05 and p<0.01, respectively, compared with patients with other neurological diseases), indicating that increased LPx in CNS may be a feature of MS. Levels of transferrin were normal but caeruloplasmin (CP), a major antioxidant plasma protein, was significantly raised in MS patients (p<0.01) and this may represent an adaptive response to increased oxidative challenge. Neither of these proteins was detectable in CSF using radial immunodiffusion. There was no significant correlation between the severity or duration of the disease nor the period since the last relapse and either LPx products of CP suggesting that the changes observed in this work are not simply the direct result of demyelination and tissue damage.

The uses and enigmas of the Al2O3-Y2O3 phase system

Abstract: The uses of the five compounds, namely Al2O3, Y3Al5O12, YAlO3, Y4Al2O9 and Y2O3, which occur in the Al2O3-Y2O3 phase system are reviewed and the uncertainties which have pervaded the existence and stability of the three intermediate phases are discussed. It is shown that the major factor which has resolved these uncertainties is the correlation achieved between phase studies and single-crystal growth data, the latter being prompted by the increased device use of the compounds within this phase system.

Procedures as persistent data objects

Abstract: A persistent programming environment, together with a language that supports first class procedures, may be used to provide the semantic features of other object modeling languages. In particular, the two concepts may be combined to implement abstract data types, modules, separate compilation, views, and data protection. Furthermore, the ideas may be used in system construction and version control, as demonstrated here.

Thermal effects and timing of thrusting in the Moine Thrust zone

Abstract: Illite crystallinity studies in the foreland to the Moine thrust belt show a widespread heating event which is interpreted as a thermal response to thrust sheet emplacement. Temperatures reached ~275°C approximately 24 Ma after the main thrusting events. Based on the relationships between syn-thrusting intrusions and the thrust planes, combined with radiometric dates from the Moine sheet, it is argued that movement on the Moine thrust started between 440 and 430 Ma ago. Contractional slip in the Moine thrust belt ceased at about 425 Ma ago and it is proposed that illite metamorphism attained temperatures of ~275° C at about 408 Ma ago.

Correlated K-distributed Clutter Models

Abstract: In this paper we examine the way in which a correlated K-distributed clutter model may be applied in the study of coherent-imaging systems. The theoretical background behind the model is discussed and various different correlated gamma-distributed surface models are analysed. The K-distributed clutter properties consequent on coherent imaging of such surfaces are next derived and their dependence on the imaging response function demonstrated. The theoretical results for a double coherence length surface model are then compared with overland images obtained with the RSRE X -band synthetic-aperture radar (SAR) processor. It is demonstrated that the model provides a reasonable representation of the dependence of the real image on the system resolution. The significance of such correlated K-distribution models on the understanding and prediction of clutter statistics is discussed and the direction for future research indicated.

Visual evoked potentials to lateralised stimuli in two cases of callosal agenesis.

Abstract: Visual evoked potentials (VEPs) to lateralised light flashes were recorded from two acallosal patients. In one patient, these recordings were made while he performed a choice-reaction time task, and in the other patient the VEPs were obtained during a simple reaction time task. In both cases the patient9s VEPs from electrode sites contralateral to the visual field of stimulus delivery resembled those of controls. Their VEPs from ipsilateral sites were aberrant, however, in that while control subjects showed a smaller and slightly delayed ipsilateral N160 component, this was not discernible in the patients9 data. It is concluded that the ipsilateral N160 relies for its generation on the transcallosal transfer of information processed initially by the contralateral hemisphere.

Psychological Theory as Intergroup Perspective: A Comparative Analysis of “Scientific” and “Lay” Accounts of Crowd Events:

Abstract: The central argument of this paper is that the popular success of crowd psychology is in part due to its correspondence with the perspective of outgroup members. This is supported by a comparative analysis of traditional crowd psychology and lay accounts of crowd events drawn from street disturbances in St. Pauls, Bristol, in 1980. Five basic types of error are identified in crowd psychology past and present. These are: (1) the abstraction of crowd episodes from their intergroup conflicts, (2) the failure to deal with underlying dynamic processes, (3) exaggeration of the anonymity of crowd members, (4) failure to understand the motives of crowd members, and (5) an overwhelming emphasis on the negativity of crowd events. Analysis of accounts of the St. Pauls disturbance reveals the centrality of these forms of error in outgroup members' versions of events. In contrast, crowd members tended to draw upon very different accounts which stress the meaningfulness of crowd action, solidarity, and positive emotion...

Modulation of epidermal cell shaping and extracellular matrix during caudal fin morphogenesis in the zebra fish Brachydanio rerio.

Abstract: Distinct changes in epidermal cell shaping largely define the overall pattern of growth and form during generation of the ectodermal ridge and early stages of fin fold morphogenesis. The epidermal portion of the ridge and early fin fold are formed from a strip of epidermal cells that is only six to nine cells wide. There is apparently no increase in the number of these cells during initial formation of the ridge and its subsequent conversion into a fin fold which contains extracellular matrix fibres. Epidermal cells adopt a wedge-shaped morphology during ridge production. Distinct changes in the shaping and contact relationships between basal portions of these cells generate intercellular spaces at several discrete loci within the ridge. These spaces become continuous with each other to form a subepidermal space. Hence, the subepidermal space is not produced by straight-forward folding of an epidermal sheet. Cells flanking the sides of the ridge start to flatten as it is converted into a fin fold. A continuous row of distinctive cells is positioned along the apex of the developing fold. The term 'cleft cells' is suggested for these apical cells. Each cleft cell retains a wedge-shaped form during fold formation and develops a basal cleft-shaped invagination. Invaginations are aligned in neighbouring cleft cells so that these cells cap the distal boundary of the subepidermal space where collagenous extracellular fibres called actinotrichia run anteroposteriorly along the length of the fin fold. This orientation is in direct contrast to the proximodistal orientation of actinotrichia within the remainder of the subepidermal space. During early stages of fold production a temporary set of previously unreported extracellular cross fibres spans the subepidermal space at right angles to actinotrichia. These configurations of extracellular fibres could be advantageous for maintaining the structural integrity of the early fin fold.

The Neural Basis of Escape Swimming Behaviour in the Squat lobster Galathea Strigosa: I. Absence of Cord Giant Axons and Anatomy of Motor Neurones Involved in Swimming

Abstract: 1. The anatomy and physiology of neurones underlying escape swimming behaviour in the squat lobster, Galathea strigosa , have been investigated, and the results are discussed in the context of the evolution of decapod escape behaviour. 2. In contrast to crayfish, hermit crabs and a number of other related decapods, Galathea does not possess a giant fibre system for escape. 3. Fast flexor motor neurones (FFs) and fast extensor motor neurones (FEs) have been shown, by cobalt backfilling, to be homologous with crayfish FFs and FEs in number, size and distribution of somata. A small degree of intersegmental and interspecific variation is noted. 4. The flexor inhibitor (FI) neurone is described in terms of its central anatomy, peripheral function and peripheral branching pattern. In each of these respects the neurone is found to be homologous with the crayfish FI. 5. The neurone homologous with the crayfish motor giant (MoG) in its soma size and position is found to be a typical FF in Galathea . This ‘MoGH’ contrasts with the crayfish MoG in having central neuropilar arborization and in lacking axonal branches in the connectives. These differences can be accounted for by the absence of cord giant axons.

Social representations in the ordinary explanation of a ‘riot’

Abstract: This paper critically examines the notion of social representations by way of a systematic analysis of media and participants' accounts of the St Pauls street disturbances of 1980. The analysis concentrates on two major explanatory categories which appear in the accounts: (A) ‘race’; (B) ‘government cuts and amenities’. In each case it is possible to distinguish three different levels of consensus between accounts: (i) particular explanatory schemata can be recognized as available but treated as mistaken; (ii) particular explanatory schemata can be recognized as relevant and adopted to explain the particular events, although in different ways; (iii) particular schemata can be adopted and used to explain events in the same way. The flexible meaning of these categories is highlighted along with the recurrent reference to alternative explanations. These findings raise problems for the suggestion that social representations minimize conflict and create ‘consensual universes’, and question the straightforward relationship between social representations and identifiable social groups. In conclusion the need is identified for a more detailed analysis of the language in which social representations are couched, and the relationship they bear to different contexts of use.

Control of suspension feeding bivalve production by current speed

Abstract: Growth experiments confirm that production by a bed of blue mussels(Mytilus edulis) may be controlled by tidal current speed through its effect on seston supply. The mechanism of this effect involves a downstream seston depletion and is thus applicable only to populations of mussels. Individual physiological responses by mussels, such as increased filtration, ingestion and assimilation rates at higher current speeds, are not involved in the enhanced bivalve production observed.