Showing papers by "Royal Holloway, University of London published in 1993"

Psychopathology and early experience: a reappraisal of retrospective reports.

Abstract: Three potential sources of error in retrospective reports of childhood experiences are documented: low reliability and validity of autobiographical memory in general, the presence of general memory impairment associated with psychopathology, and the presence of specific mood-congruent memory biases associated with psychopathology. The evidence reviewed suggests that claims concerning the general unreliability of retrospective reports are exaggerated and that there is little reason to link psychiatric status with less reliable or less valid recall of early experiences. Nevertheless, it is clear that steps must be taken to overcome the limitations of retrospective reports and enhance their reliability.

Doing Research on Sensitive Topics

Abstract: Introduction Limits on Inquiry Estimating the Size of Hidden Populations Sampling Rare or Deviant Populations Asking Sensitive Questions on Surveys Asking Sensitive Questions Interviewing The Access Process in Research on Sensitive Topics Covert, Adversarial and Collaborative Research Handling Sensitive Data Disclosure and Dissemination in Research on Sensitive Topics Conclusion

Palaeozoic and Cenozoic lithoprobes and the loss of >120 km of Archaean lithosphere, Sino-Korean craton, China

Abstract: In eastern China Palaeozoic kimberlites and Cenozoic basalts have been erupted through the same Archaean crust, thus providing deep probes of the cratonic lower lithosphere over a period of 400 Ma. While Palaeozoic diamondiferous kimberlites point to the existence of thick, refractory lower lithosphere in the east, Cenozoic basalt-borne xenoliths reveal the presence of hot, thin, less refractory lower lithosphere. Remnants of the Archaean lithosphere may have survived as harzburgites which are chemically similar to those from the Kaapvaal craton but very different from recently accreted lherzolites. In the absence of convincing evidence for supra-subduction or intraplate processes it is believed that the dramatic change of lithosphere architecture in the Phanerozoic was caused by indentor tectonics resulting from the collision of India and Eurasia. Passive reactivation and remobilization of the Archaean lower lithosphere, in particular metasome horizons, contributed to Cenozoic magmatism aligned along major lithospheric faults. Traditionally the oldest Archaean cratonic nuclei are thought of as the most stable, inert parts of the Earth's surface. In the case of South Africa, Canada and Western Australia, Archaean cratons (Liu et al. 1992) lie atop a thick mechanical boundary layer characterized by high velocity anomalies (Anderson et al. 1992). In addition, the occurrence of Archaean P-type diamonds in on-craton kimberlites confirms the presence of an ancient thick lithospheric keel that, in some cases, was stabilized to depths of 200 km in the first billion years of Earth's history (Boyd & Gurney 1986). However, not all cratons have retained their structural integrity. In the case of the GreenlandHebridean craton, elevated mantle temperatures associated with the Iceland plume and tectonic forces related to the opening of the North Atlantic, may have been responsible for erosion of the craton margin. This would account for the existence of thinned Archaean crust (< 30 km) on the eastern Atlantic margin (i.e. Hebridean craton) and the survival of a thick cratonic nucleus in Greenland (Scott-Smith 1987). Similarly a thick cratonic keel does not underlie the SinoKorean Archaean craton, eastern China. Detailed seismic tomography (Chen et al. 1991; Liu 1992) indicates that the 'present-day' lithosphere is < 80 km thick (see Fig. 4) with greatly thinned lithosphere around the Bohai Sea (Ma & Wu 1981). The presence of thin lithosphere with a low velocity structure similar to an ocean ridge is substantiated by heat flow studies in eastern China (Teng et al. 1983) which reveal a region of very high heat flow on the craton in the vicinity of the Bohai Sea and Beijing (Fig. 1). The measured heat flow (1.2-2.53 HFU) corresponds to geotherms observed in tectonically active continents or ocean basins (50-105 mW m-Z). The aim of this paper is to review the temporal evolution of the lower lithosphere beneath the Sino-Korean craton, a crustal province known to contain some of the oldest crustal rocks on Earth (Jahn et al. 1987). In this review we will: (a) present petrological and geochemical evidence for the character of the Palaeozoic and Cenozoic lithosphere; (b) review the available geological and geochemical data on eastern China pertinent to lithosphere evolution, (c) outline a model to explain the temporal changes in lithosphere architecture. Palaeozoic kimberlite-borne xenoliths Palaeozic (400 Ma) kimberlites entrain a variety of xenoliths and megacrysts including diamonds (Lu et al. 1991; Zhang et al. 1991; Chi et al. 1992) (Fig. 1). While the petrology, mineralogy and thermal history of peridotite xenoliths and heavy mineral concentrates have been determined across the Sino-Korean craton, very little geochemical data are available for these xenoFrom Prichard, H. M., Alabaster, T., Harris, N. B. W. & Neary, C. R. (eds), 1993, Magmatic Processes and Plate Tectonics, Geological Society Special Publication No. 76, 71-81. 71 at Royal Holloway University of London on July 10, 2013 http://sp.lyellcollection.org/ Downloaded from

Towards Operational Measures of Computer Security

Abstract: Ideally, a measure of the security of a system should capture quantitatively the intuitive notion of 'the ability of the system to resist attack'. That is, it should be operational, reflecting the degree to which the system can be expected to remain free of security breaches under particular conditions of operation (including attack). Instead, current security levels at best merely reflect the extensiveness of safeguards introduced during the design and development of a system. Whilst we might expect a system developed to a higher level than another to exhibit 'more secure behaviour' in operation, this cannot be guaranteed; more particularly, we cannot infer what the actual security behaviour will be from knowledge of such a level. In the paper we discuss similarities between reliability and security with the intention of working towards measures of 'operational security' similar to those that we have for reliability of systems. Very informally, these measures could involve expressions such as the rate of occurrence of security breaches (cf rate of occurrence of failures in reliability), or the probability that a specified 'mission' can be accomplished without a security breach (cf reliability function). This new approach is based on the analogy between system failure and security breach. A number of other analogies to support this view are introduced. We examine this duality critically, and have identified a number of important open questions that need to be answered before this quantitative approach can be taken further. The work described here is therefore somewhat tentative, and one of our major intentions is to invite discussion about the plausibility and feasibility of this new approach.

Technology and Religious Change: Islam and the Impact of Print

Abstract: A historian, like any other scholar, incurs many debts. I am no exception. I would like to begin this occasion by acknowledging some of those debts. I have benefited greatly from the generosity of colleagues—from the generosity of colleagues in my particular field of Islamic and South Asian history in North America, Europe and the Subcontinent, but also from the generosity of historians in general. It is a great privilege to work amongst historians in the University of London, who form arguably the largest group of historians in the world, that work together.

The profilin multigene family of maize: differential expression of three isoforms

Abstract: Profilin is a small (12-15 kDa) actin- and phospholipid-binding protein previously known only from studies on animals and lower eukaryotes but recently identified as a birch pollen allergen. Here we have identified and characterized three members of the profilin multigene family from the plant Zea mays. Two cDNAs isolated from a maize pollen library (ZmPRO 1 and ZmPRO 3) each have a single, large open reading frame encoding a putative polypeptide 131 amino acids long with a predicted molecular weight of approximately 14 kDa. A third maize pollen cDNA (ZmPRO 2) has two in-frame translation initiation codons. Use of the first ATG would result in a polypeptide 137 amino acids long with a molecular weight of 14.8 kDa. The three maize profilins are highly homologous to each other (> 90% nucleotide and amino acid sequence identity) as well as other plant profilins but show far less similarity (30-40% amino acid sequence identity) to animal and lower eukaryote profilins. Multiple sequence alignments indicate that only nine residues are shared by all eukaryotic profilins examined. However, limited comparisons reveal domains in the NH2 and COOH termini that have a high degree of similarity suggesting functional conservation. The maize gene family size is estimated to contain three to six members based on Southern blot experiments with gene-specific and coding region probes. Northern blot analysis demonstrates that the three maize profilin cDNAs characterized here are utilized in a tissue-specific manner and are anther or pollen specific.

Development of child-centered disease-specific questionnaires for living with asthma

Abstract: Contemporary developments in the management of chronic diseases such as diabetes and asthma offer possibilities for optimal control, but patients increasingly need to take on responsibilities for self care. Health professionals require comprehensive assessments of outcome that include data reflecting patients' perceptions of their disorder and its management. Disease-specific, patient-centered questionnaires for evaluation of adults' health-related quality of life are available for diabetes and asthma. Little progress is evident in relation to pediatric instruments. This paper describes the development of such an instrument for measurement of 8- to 11-year-olds' perceptions of their asthma--the CAQ-B Psychometric characteristics of the CAQ-B are reported: principal axis factor analysis resulted in the derivation of four subscales reflecting children's perceptions of both active and passive aspects of living with asthma, together with their perceptions of its severity and any associated distress. Preliminary explorations with CAQ-B included comparisons of parents', doctors', and children's ratings of severity; comparisons of data from asthmatic and nonasthmatic children; comparisons of data from boys and girls.

On the Replacement of the Red Squirrel in Britain. A Phytotoxic Explanation

Abstract: Diffusion modelling has shown that conservative demographic traits combined with feeding competition could explain red squirrel replacement by grey squirrels. We used field data from seven separate red and grey squirrel populations, in oak-hazel woods and Scots pines, to reject the hypothesis that red squirrel density and breeding is intrinsically poorer than that of grey squirrels. In oak-hazel woods, grey squirrel foraging, density and productivity were related to oak and acorn abundance. In contrast, red squirrels foraged where hazels were abundant; their relatively low density and breeding success were related to the abundance of hazel nuts. Red squirrels failed to exploit good acorn crops, although acorns were more abundant than hazels, but in Scots pines had densities and breeding success as high as grey squirrels in deciduous woods. Captive grey squirrels thrived on a diet of acorns, but red squirrels had a comparative digestive efficiency of only 59%, apparently because they were much less able than grey squirrels to neutralize acorn polyphenols. A model with simple competition for the autumn hazel crop, which was eaten by grey squirrels before the acorn crop, shows that red squirrels are unlikely to persist with grey squirrels in woods with more than 14% oak canopy. With oaks in most British deciduous woods giving grey squirrels a food refuge which red squirrels fail to exploit, replacement of red squirrels can be explained by feeding competition alone, exacerbated by the post-war decline in coppiced hazel.

Stratigraphy and structure of the Maltese graben system

Abstract: The Maltese graben system is a series of Miocene–Quaternary extensional basins located in the foreland of the Sicilian Apennine–Maghrebian fold and thrust belt. The tectono-sedimentary development of the graben was determined from the first fully integrated analysis of the area to include onshore field and hydrological borehole data, together with offshore reflection seismic data and exploration wells. The NW–SE- and ENE–WSW-trending rifts have a coeval, four phase tectono-sedimentary evolution revealed by a succession of platform and pelagic carbonates. The pre-rift phase (>21 Ma) is followed by a early syn-rift phase (21–6 Ma) characterized by evidence for relatively minor extensional faulting including the development of neptunian dykes. Major fault activity occurred during the succeeding late syn-rift phase ( β = 1.03–1.17) across the rift structures, major basin bounding extensional faults have throws of up to 2.2 km. Fault slip data indicate that both NW–SE and ENE–WSW rift trends were generated in response to N–S stretching. These results are in accord with Argnanis (1990) description of a major N–S orientated transfer fault located 50 km west of the present study area.

Stomatal Density Responds to the Glacial Cycle of Environmental Change

Abstract: Examining the response of stomatal density to past changes in atmospheric CO$\_{2}$ concentration helps us to understand how plants adapted to palaeoenvironmental change, and so helps in predicting their response to future global environmental change. Stomatal density is an important physiological parameter that underpins the productivity of terrestrial vegetation by affecting both rate of carbon uptake and water use efficiency. Previous work on temperate tree species showed a decrease in stomatal density in response to a 60 p.p.m.v. increase in atmospheric CO$\_{2}$ concentration over the past 200 years. However, such a short timespan largely excludes the genetic component of plant adaptation to change in CO$\_{2}$ concentration. We present the first record of stomatal density from fossil leaves extending over 140 ka. Our record for the arctic-alpine dwarf shrub Salix herbacea L. extends back to the penultimate glacial stage, spanning two intervals when atmospheric CO$\_{2}$ concentration was considerably lower (by ca. 170 p.p.m.v.) than at present. Our results demonstrate a decrease in stomatal density in response to long-term increases in atmospheric CO$\_{2}$ concentration, and are in accordance with previous short-term observations and experiments. This implies that relaxation of the stress imposed by low atmospheric CO$\_{2}$ concentration has enabled terrestrial plants to exhibit an adaptive response to the other limiting factor of water availability by reducing stomatal density and hence improving water use efficiency.

Separating mantle from slab signatures in arc lavas using B/Be and radiogenic isotope systematics

Abstract: AT convergent margins, tectonic processes juxtapose subducted slab, mantle wedge and the crust of the upper plate in a column beneath the overlying arc volcano. As each of these components is expected to be chemically heterogeneous, and as all may contribute to magma chemistry, identifying the different sources of arc magmas has been difficult. A working hypothesis has emerged, in which tholeiitic and calc-alkaline lavas in island arcs are partial melts of the mantle produced by fluxing of the wedge by hydrous fluids from the subducted slab1,2. Trace-element and radiogenic isotope ratios have been used to define the chemical characteristics of these sources but cannot be unequivocally identified with one source; by contrast, high B/Be and 10Be/9Be ratios in arc lavas uniquely identify the subduction component3,4, and thus separate chemical variability owing to recent subduction from that reflecting other causes. Here we combine B/Be with Sr, Nd and Pb isotope systematics of alkaline, calc-alkaline and tholeiitic lavas from Java and Flores, Indonesia, to constrain the isotopic composition of their mantle and subduction sources. The alkaline lavas always have low B/Be, from which we conclude that they are derived from mantle that has not been modified by recent subduction (in agreement with refs 5 and 6). We also show that the isotopic composition of the subducted component is relatively homogeneous along the length of the arc, suggesting that the subduction of Australian continental lithosphere in the east started too recently to have changed the nature of the subducted material at present beneath Flores.

The Middle Pleistocene deposits of Waverley Wood Pit, Warwickshire, England

Abstract: A complex of channels underlying the Baginton-Lillington Gravel (Baginton Formation) at Waverley Wood Quarry, Warwickshire is described. Fossil pollen and plant macrofossils, Coleoptera, Ostracoda, Mollusca and Mammalia are described from the channel-fill deposits. Consideration of all the evidence allows the identification of four separate stages of channel fill which largely occurred under a cool temperate climate. At the top of Channel 2 evidence for a cold, continental climatic episode can be recognised, suggesting that the whole complex was deposited under a fluctuating climate at the end of a temperate stage. At two levels in the channels human artefacts were recovered confirming the presence of Palaeolithic people in Warwickshire during the deposition of the sediments. Amino-acid geochronology suggests an age within the ‘Cromerian Complex’ Stage for the channels. The small vertebrate and molluscan faunas indicate that the deposits are no older than the latter part of the ‘Cromerian Complex’ Stage of East Anglia. The regional stratigraphic significance of the Waverley Wood succession is outlined.

Evolutionary responses of stomatal density to global CO2 change

Abstract: Stomatal density is known to respond to CO2 levels during leaf development. Current interest in the increasing concentration of atmospheric CO2 has stimulated much experimentation on the responses of plants to relatively short-term exposure in artificially high CO2 levels. Attempts to extrapolate from short-term to long-term responses raise fundamental questions concerning evolutionary change in response to rising global CO2 levels. We consider the improved water use efficiency observed under elevated CO2 levels to be the main driving force of natural selection affecting the genotypic component controlling stomatal density. Whether a response is merely phenotypic or becomes incorporated into the genotype depends on two factors: (i) the time scale of exposure and (ii) the generation time of a species. Measurements of stomatal density on fossil leaves of Salix herbacea through a glacial cycle covering the last 140 000 years have shown a decrease in stomatal density in response to the rising CO2 levels of this period. This accords with the shorter-term observations on leaves of trees seen in herbarium specimens where the stomatal density has decreased in response to the rising CO2 levels of the last 200 years. The results indicate that natural selection over the 140000-year period may have favoured a similar response to that shown by trees phenotypically over the last 200 years. Since there is now some evidence for the genetic control of stomatal density, the role of natural selection affecting it must be considered when translating responses from short-term experiments to predict how stomatal density will be affected by long-term climatic and atmospheric change.

Induction of alpha-galactosidase in Penicillium ochrochloron by guar (Cyamopsis tetragonobola) gum.

Abstract: High yields of extracellular alpha-galactosidase from fungal cultures were obtained by inducing enzyme production with guar gum (a galactomannan obtained from the seeds of Cyamopsis tetragonobola) as the sole carbon source. An alpha-galactosidase was isolated from the culture medium of Penicillium ochrochloron culture and purified 867-fold by CM-cellulose and Sephacryl S-200 column chromatography to apparent homogeneity. Gel-filtration data revealed an M(r) of 57,500, which was in close agreement with SDS/PAGE M(r) estimation, for a single band, of 60,200. The alpha-galactosidase activity is strictly dependent upon the pH and temperature of the incubation medium, being maximal at pH 4.5 and 55 degrees C respectively. This enzyme from P. ochrochloron was isolated and purified, devoid of beta-mannanase activity, which cleaves the main beta-mannan backbone of galactomannans and greatly diminishes its gel-promoting capacity. The properties of purified guar-gum-induced alpha-galactosidase activity in P. ochrochloron culture were evaluated in order to ascribe a possible application for alpha-galactosidase in the controlled generation of an improved guar-gum-based gel promoter.

The Ecotron: A Controlled Environmental Facility for the Investigation of Population and Ecosystem Processes

Abstract: This paper reports on aspects of the design and philosophy of the Ecotron, an integrated series of 16 controlled environmental chambers at the NERC Centre for Population Biology. The Ecotron serves as an experimental means for analysing population and community dynamics and ecosystem processes under controlled physical conditions. Within the chambers, terrestrial experimental communities are assembled into foodwebs of desired complexity from a pool of species selected for their preadaptations to the physical conditions of the Ecotron. These species include decomposers (earthworms, snails, microarthropods and microbes), primary producers (16 species of plants), primary consumers (four species of herbivorous arthropods), and secondary consumers (four species of parasitoids). The design of the Ecotron is unique in several aspects with respect to its blend of biology and technology. It supports small, dynamic communities of up to 30 plant and metazoan species, thereby making it among the more biologically complex controlled environmental systems currently in use. Its architecture permits replication and variation of spatial scale in experimental design. Its artificial climate simulates natural environmental conditions within chambers allowing experimental control over light, water, temperature, humidity, and in the near future CO $_{2}$ and UV-B radiation. Sensors monitor both macro- and micro-environmental conditions of a number of physical factors within the chambers. Preliminary experiments show the Ecotron to be an excellent facility for long-term population and community-level experiments. We discuss the results of one of these early experiments and briefly consider ongoing and future experiments.

The Limits of Property-Led Regeneration

Abstract: In this paper, the role of property development in city revitalization is considered. Case study material is used to analyze the changing organizational nature of property development, especially the interrelationships between property developers and the traditional purveyors of urban policy: Local authorities. It is shown how the property industry is dependent on the development of organizational capacities with public authorities in a manner not anticipated by the rhetoric of central government, a rhetoric which has pushed the property-led approach as an alternative to development by, and through, the public sector. In contrast to this view, illustrative material is presented which indicates how property-led development is highly dependent on the public sector. Also illustrated is how the process of property-led regeneration has the capacity to undermine a range of local, community, interests in areas affected by redevelopment schemes, a situation which has been exacerbated by the prioritization of the ...

The relationship of social network deficits with deficits in social functioning in long-term psychiatric disorders.

Abstract: It has been suggested that deficits or impairments in social functioning may explain the depleted support networks of the mentally ill. With this in mind, 145 long-term users of day care psychiatric facilities, 57% of whom had a life-time diagnosis of schizophrenia, were examined to determine whether deficits in social and survival skills explained deficits in their social networks. Compared with patients with acute depression, long-term patients had smaller social networks. There was a very small but statistically significant association between observer ratings of deficits in social functioning (daily social and living skills) and self-reported family social networks size. Behavioural problems were also associated with smaller family networks. Among the long-term patients, duration of service contact and type of disorder (affective vs nonaffective psychosis) were not related to network size. These preliminary findings are discussed.

The stability of the vocal signature in phee calls of the common marmoset, Callithrix jacchus.

Abstract: Phee calls were recorded from five captive common marmosets on three occasions. An initial recording session was followed by further sessions 1-12 days later, and finally, 12 months after the initial sample. Sonograms from the first recordings were measured using one duration and five frequency parameters, and significant differences between individuals were found for all six parameters. Discriminant function analysis was then applied to classify each call to a particular individual, witn a resulting classification accuracy of 97.27%. Analysis of the second and third recordings demonstrated accurate classification to the same caller using the measurements obtained from the initial sample. The accuracy remained high despite intra-individual differences in acoustic structure among the three recording periods. Such differences may well reflect proximate changes in the underlying arousal state of the caller. Stability over time in the vocal signature of the phee call supports the view that this vocalization may be important in signalling individual identity over long distances, in a habitat where visual contact is limited. © 1993 Wiley-Liss, Inc.

The Composition of Sporopollenin and its use in Living and Fossil Plant Systematics

Abstract: Previous investigations of sporopollenin using 13C Solid State Nuclear Magnetic Resonance have demonstrated differences between the major groups of plants in the composition of this acetolysisresistant biomacromolecule. The work presented here corroborates these results and suggests that sporopollenin obtained from seed megaspore-membranes differs slightly from that of pollen from the same plant group. Spectra obtained using NMR have been subjected to multivariate analysis. This approach has provided information which may be interpreted in phylogenetic terms. A number of fossil sporopollenins have also been investigated. These all show considerable degradation through diagenesis but retain certain characteristics of the original sporopollenin composition. Microspores and megaspores from the same species of Carboniferous arborescent lycopsid have also been investigated with a view to discerning any differences in composition that may exist between these sources of sporopollenin in the fossil recor...

Chemical composition and ultrastructure of fossil and extant salvinialean microspore massulae and megaspores

Abstract: The resistant remains of salvinialean microspore massulae and megaspores have been analyzed using scanning and transmission electron microscopy and Curie-point pyrolysis. The results show a selective enrichment of specific tissues in the fossil samples. The resistant compound, sporopollenin, in these fossil remains, is shown to consist of an oxygenated aromatic, and an aliphatic moiety. The latter is selectively enriched during diagenesis and upon oxidation. The organic matter of the extant samples is dominated by compounds which, during diagenesis, are selectively removed. The morphologically distinct megaspores and microspores are chemically comparable. Furthermore, although the genera studied are strongly distinctive in morphology and ultrastructure, the variation in their chemistry is too small to use for chemotaxonomy.

Ensialic origin for the Ngezi Group, Belingwe greenstone belt, Zimbabwe

Abstract: Volcanic rocks of the Ngezi Group in the Belingwe greenstone belt have been interpreted as continental basalts extruded onto, or oceanic crust obducted onto, a succession of stable-shelf sedimentary rocks that nonconformably overlie continental basement. The volcanic succession locally contains quartzose sandstones, and the stratigraphy is unlike ocean crust. Primary volcanic and sedimentary structures indicate a shallow-subaqueous to subaerial origin. All structural features are compatible with later refolding of an autochthonous successon; there is no structural manifestation of obduction. These criteria refute an oceanic setting for the volcanic rocks; rather, they are consistent with an ensialic origin for the Ngezi Group.