Showing papers by "Royal Holloway, University of London published in 1991"

Bias in interpretation of ambiguous sentences related to threat in anxiety.

Abstract: In the 1st of 2 experiments, currently clinically anxious, recovered clinically anxious, and normal control subjects were presented with a mixture of unambiguous and ambiguous sentences; both threatening and nonthreatening interpretations were possible for the latter. A subsequent recognition-memory test indicated that the currently anxious subjects were more likely than normal control and recovered anxious subjects to interpret the ambiguous sentences in a threatening fashion rather than in a nonthreatening fashion. This suggests that the biased interpretation of ambiguity found in currently anxious subjects reflected their anxious mood state. A 2nd experiment established that the difference in interpretative processes between currently anxious and control subjects was not due to response bias and that the interpretative bias was a reasonably general one.

Early and early Middle Pleistocene correlations in the Southern North Sea basin

Abstract: On April 8, 1988 a discussion meeting took place at Norwich with the aim of establishing correlations of the Early and Middle Pleistocene stages across the southern North Sea. On the basis of faunal, floral, and palaeoclimatic data the following correlations were considered highly probable. The Pastonian Stage of East Anglia is correlated with the Late Tiglian (TC5) Stage of the Netherlands, and the Bramertonian with the Middle Tiglian (TC1-4b). The possibility that the British Antian and Bramertonian Stages may represent parts of a single climatic event is mentioned. The Ludhamian is probably of Early Tiglian age and the Pre-Ludhamian may equate in part with the Praetiglian Stage. Possible correlation of the Waltonian with part of the Pliocene Reuverian Stage is also suggested. In the later Middle Pleistocene, the Anglian Stage correlates with the continental Elsterian. The precise correlation of the British type Cromerian Stage with part of the ‘Cromerian Complex’ Stage in the Netherlands remains uncertain.

Carbonic fluid inclusions in South Indian granulites: evidence for entrapment during charnockite formation

Abstract: Field evidence and fluid inclusion studies on South Indian incipient charnockites suggest that charnockite formation occurred during a decompressional brittle regime following the ‘peak’ of metamorphism and regional deformation. The most abundant type of inclusions in quartz and garnet grains in these charnockites contain high-density carbonic fluids, although lower-density fluids occur in younger arrays of inclusions. Discrete fluid inclusion generations optically are observed to decrepitate over well-defined temperature intervals, and quantitative measurements of CO2 abundance released from these inclusions by stepped thermal decrepitation show up to a four-fold increase (by volume) in the incipient charnockites relative to the adjacent gneisses from which they are derived. Studies based on optical thermometry, visual decrepitation and stepped-heating inclusion release together indicate that entrapment of carbonic fluids coincided with charnockite formation. We confirm that an influx of carbon dioxide-rich fluids is associated with the amphibolite-granulite transition, as recorded by the incipient charnockites, the remnants of which are commonly preserved as the earliest generation of high-density fluid inclusions.

High-precision multicollector isotopic analysis of low levels of Nd as oxide

Abstract: 30 ng Nd samples loaded with silica gel and phosphoric acid on single rhenium filaments reproducibly provide 144 NdO + ion beams of1.5–2·10 −11 A for several hours, without need of a poor source vacuum, or need to introduce oxygen into the mass spectrometer source. The loading technique discriminates strongly against CeO + , and accurate normalization for mass fractionation to 142 Nd/ 144 Nd is possible. A 5-collector procedure for analysis and interference correction ( 18 O, 17 O overlaps, CeO + , PrO + , SmO + ) is described which permits analysis of 30 ng Nd loads to internal precision of ±0.000005 (2se) in2.5 hr. 17 loads (each 30 ng) of the laboratory Nd standard (analysed March–June 1990) yielded external precision of ±0.000007 (2sd) on 143 Nd/ 144 Nd, and 143 Nd/ 144 Nd and 145 Nd/ 144 Nd values within 2se of the value determined on 500 ng Nd + runs, and a further 17, analysed October 1990–April 1991, give identical results within error. Eight sample analyses also agree within 2se between Nd + and NdO + analyses, the latter being loaded from rinses of the disposable pipette tips used to load the Nd + runs.

Iron absorption during normal human pregnancy: a study using stable isotopes.

Abstract: The absorption of iron has been determined in nine healthy women studied serially during pregnancy and once post delivery. Following the oral administration of 5 mg aqueous 54FeSO4 plus ascorbic acid and the intravenous injection of 200 micrograms 57FeSO4, the isotope ratios of 54Fe: 56Fe and 57Fe: 56Fe in serum were measured by the use of inductively-coupled-plasma mass spectrometry whereby metal ions are vaporized into an argon plasma without previous blood sample preparation. Mean oral Fe absorption was 7.6 (range 1-22)% at 12 weeks gestation, 21.1 (range 9-58)% at 24 weeks, 37.4 (range 18-56)% at 36 weeks and 26.3 (range 8-54)% at 12 weeks post delivery. All the other biochemical and haematological indices were within normal limits for pregnancy. The significant increase (P less than 0.01) in Fe absorption during normal pregnancy suggests that most women would have the potential to meet the Fe demands of pregnancy without the need for supplementation if dietary Fe has similar availability to the aqueous preparation.

Aspects of Seleucid Royal Ideology: The Cylinder of Antiochus I from Borsippa

Abstract: A major contention of our book Hellenism in the East was that the most profitable way for making progress in understanding the Achaemenid and Seleucid empires was to try to evaluate, sensitively, the very disparate types of evidence within their own social and cultural contexts, however difficult this might be in practice. In the case of the Antiochus I cylinder we are confronted by an inscribed object whose significance lies as much in its physical form as in the content of the text it bears. These aspects are inextricably intertwined as part of a tradition specific to Mesopotamian culture—object and text combined are the physical representation of a major, longstanding, sociopolitical institution for which a mass of earlier evidence exists. It is all too understandable that Greco-Roman scholars, who have been the primary students of the hellenistic world, should find it hard to know how to approach such material emanating from an unfamiliar cultural milieu. Yet, for once, this text is not fragmentary—it is a long, well-preserved document, easy to read and readily accessible in translation which in itself demonstrates an acknowledgment by hellenistic historians of the potential importance of this non-Greek text for understanding Seleucid history.

The distribution of planktonic dinoflagellates and their cysts in the eastern and northeastern Atlantic Ocean

Abstract: summary Data are presented on the distribution of both planktonic dinoflagellates and their cysts from 20° N to 70° N and from the western coasts of Europe and Africa to 25° W in the eastern and northeastern Atlantic Ocean. Although most of the thecate dinoflagellates are widely distributed, sometimes with a discontinuous pattern, the cysts are generally more restricted. There is an increase in the ratio of cyst types to thecate plankton and in cyst diversity from ocean to inshore and from low to high latitudes; in both cases paralleling an increase in diversity of the plankton. Cyst distributions may also be discontinuous, occurring around the British Isles and also in the upwelling area off N.W. Africa. Particular species show similar distribution patterns for cyst and thecae e.g. Polykrikos schwarzii; distribution patterns where the cyst is less widely distributed than the thecae e.g. Spiniferites bentori/Gonyaulax digitalis; and where the cysts are more widespread than the thecae as in the problematical Gonyaulax spinifera‘complex’. Difficulties identified in comparing data sets include the lack of detailed knowledge of dinoflagellate life cycles, the need to know more about environmental parameters affecting encystment, and knowledge of cyst transportation and preservation in sediments. Overall cyst distribution patterns may be compared to the broad coccolithophorid zones recognised in the Atlantic Ocean.

Complete sequence and model for the A2 subunit of the carotenoid pigment complex, crustacyanin.

Abstract: The complete sequence has been determined for the A2 subunit of crustacyanin, an astaxanthin-binding protein from the carapace of the lobster Homarus gammarus. The polypeptide chain is 174 residues long and is similar to proteins of the retinol-binding protein superfamily. Some regions of the sequence are most similar to the retinol-binding protein, beta-lactoglobulin subgroup, while the disulphide bonding pattern is more akin to that seen in the porphyrin binding proteins insecticyanin and bilin-binding protein. It is beginning to appear as though this superfamily of proteins, characterized by a similar gross structural framework, may be further subdivided into interrelated subclasses. Model building based on the coordinates of the known structure of human plasma retinol-binding protein and on empirical prediction algorithms has allowed the putative identification of side-chains which line the binding cavity. This pocket is larger than in retinol binding protein and beta-lactoglobulin but does not allow the carotenoid to adopt a folded conformation. The amino acid composition of the pocket does not support a 'charge-shift'-type hypothesis to support the bathochromic shift phenomenon which takes place on interaction of the chromophore with the protein. Instead aromatic side-chains may play a prominent role.

Comparison of isolates and species of Toxocara and Toxascaris by biosynthetic labelling of somatic and ES proteins from infective larvae

Abstract: Infective-stage larvae of three different isolates of Toxocara canis were intrinsically ([35S]methionine) labelled in culture, to determine the presence of similarities or differences in the somatic and ES antigens expressed between larvae derived from different hosts and different geographical regions. Two other closely related ascaridids, Toxascaris leonina which infects cats and dogs, and Toxocara vitulorum (Neoascaris vitulorum) which infects cattle, were also compared to T. canis larvae by this method. Overall comparisons were made by 1- and 2-dimensional electrophoresis, while immunological cross-reactivities between the different species were analysed by radio-immunoprecipitation. Our results show that extensive physicochemical characteristics are shared between T. canis isolates, both from different hosts and different geographical locations. A substantial overlap was revealed when T. canis and T. vitulorum antigens were compared, whereas Toxascaris was found to produce a distinct antigen profile: this result was independent of whether methionine- or Iodogen-labelled products were being considered. Antigen recognition by polyclonal antibodies raised to all three species and to the cat ascaridid Toxocara cati, revealed considerable cross-reactivities. The cross-reactions were especially prominent between the Toxocara species, a fact further substantiated when reactivity of T. canis ES-specific monoclonal antibodies were tested against T. leonina and T. vitulorum antigens. The ES antigens of T. leonina were not recognized by the T. canis monoclonals, whereas the majority of these antibodies precipitated antigens of T. vitulorum. One which did not react with T. vitulorum was monoclonal antibody Tcn 2, indicating its species-specific reactivity and therefore its potential for the specific diagnosis of human toxocariasis.

Complete sequence and model for the C1 subunit of the carotenoprotein, crustacyanin, and model for the dimer, beta-crustacyanin, formed from the C1 and A2 subunits with astaxanthin.

Abstract: The complete sequence has been determined for the C1 subunit of crustacyanin, an astaxanthin-binding protein from the carapace of the lobster Homarus gammarus (L.). The polypeptide, 181 residues long, is similar (38% identity) to the other main subunit, A2 and to plasma retinol-binding protein. The tertiary structure of the C1 subunit has been modelled on that derived for the A2 subunit from the coordinates of retinol-binding protein. Residues lining the putative binding cavities and at the putative carotenoid binding sites of the two subunits are highly conserved. The carotenoid environments are characterized by a preponderance of aromatic and polar residues and the absence of charged side-chains. A tentative model for the dimer, β-crustacyanin, formed between the two subunits with their associated carotenoid ligands, is discussed. The model is based on the crystal structure of the dimer of bilin-binding protein, a member of the same superfamily. This structure has enabled us to examine mechanisms for the bathochromic spectral shift of the protein-bound carotenoid and to identify likely contact regions between dimers in octameric α-crustacyanin.

Path integral simulation of the free energy of (Lennard-Jones) neon

Abstract: The quantum mechanical contribution to the free energy of simple fluids can be conveniently determined by path integral simulation and ‘λ-integration’, choosing the classical fluid as reference system. In this paper the method is applied to liquid Lennard-Jones (LJ) neon. The properties of the quantum mechanical and the classical liquids are compared with each other and with experimental data.

Near-constancy phenomena in branching processes

Abstract: The occurrence of certain ‘near-constancy phenomena’ in some aspects of the theory of (simple) branching processes forms the background for the work below. The problem arises out of work by Karlin and McGregor [8, 9]. A detailed study of the theoretical and numerical aspects of the Karlin–McGregor near-constancy phenomenon was given by Dubuc[7], and considered further by Bingham[4]. We give a new approach which simplifies and generalizes the results of these authors. The primary motivation for doing this was the recent work of Barlow and Perkins [3], who observed near-constancy in a framework not immediately covered by the results then known.