Showing papers by "Keele University published in 1992"
01 Aug 1992
TL;DR: The actor-network theory as discussed by the authors is a body of theoretical and empirical writing which treats social relations, including power and organization, as network effects and argues that society and organization would not exist if they were simply social.
Abstract: This paper describes the theory of the actor-network, a body of theoretical and empirical writing which treats social relations, including power and organization, as network effects. The theory is distinctive because it insists that networks are materially heterogeneous and argues that society and organization would not exist if they were simply social. Agents, texts, devices, architectures are all generated in, form part of, and are essential to, the networks of the social. And in the first instance, all should be analyzed in the same terms. Accordingly, in this view, the task of sociology is to characterize the ways in which materials join together to generate themselves and reproduce institutional and organizational patterns in the networks of the social.
2,439 citations
TL;DR: In this article, the authors outline a number of techniques for the analysis of cause maps and make the arguments about cause-map analyses concrete, suggesting what the various analyses described might imply for an understanding and evaluation of cognitive complexity.
Abstract: Cause maps are coded following many different conventions. It is therefore arguable that there can be no general approach to their analysis. Indeed the interpretation and meaning of the analysis can only be undertaken in relation to both the purpose of the research and the theoretical basis of the form of representation to be analysed, be it a cause map, network, or any other graphical picture. Given these reservations, this article outlines a number of techniques for the analysis of cause maps. In order to make the arguments about cause-map analyses concrete, the article suggests what the various analyses described might imply for an understanding and evaluation of cognitive complexity. It does not address the difficult issue relating to the status of cognitive complexity as measured in these ways but rather simply notes that they are each as plausible or more plausible than many others that are often used. Ultimately- the measures are to be taken as a portfolio of indicators of the complexity of the map itself.
571 citations
TL;DR: The basic principles for design of soluble polymeric drug delivery systems are explained and illustrated using examples drawn from studies on the development of N-(2-hydroxypropyl)methacrylamide copolymer conjugates for use in cancer chemotherapy.
Abstract: Use of polymeric drug delivery systems is rapidly becoming an established approach for improvement of cancer chemotherapy. Zoladex, a poly lactide-co-glycolide subcutaneous implant that delivers a luteinizing hormone releasing hormone analog over 28 days, is now the treatment of choice for prostate cancer, and a polyanhydride matrix containing BCNU is currently in phase III evaluation for treatment of glioma multiforme. Soluble polymers were first proposed as targetable drug carriers in the mid-1970s, and although the first conjugates are still at an early stage of development some, e.g. SMANCS (styrene maleic acid-neocarzinostatin) and monomethoxypolyethyleneglycolasparaginase, are now undergoing clinical evaluation and show considerable promise. Polymeric drug delivery systems are usually designed to produce an improved pharmacokinetic profile of an antitumor agent (controlled release) and in addition soluble carriers can achieve either first-order (organ specific) or second-order (tumor specific) drug targeting by virtue of the fact that they are usually administered intravenously and should theoretically access primary and secondary disease. Soluble polymeric carriers have the potential to improve the activity of conventional antitumor agents, peptide and protein drugs, and have recently been used in constructs for delivery of oligonucleotides. With increased awareness that the successful design of a polymeric drug delivery systems can only be achieved with prior consideration of the pathology and stage of the disease, tumor accessibility, biochemistry and cell biology of the target site, choice of appropriate therapeutic agent(s) and understanding of their fundamental mode of action, we have seen the emergence of a number of exciting and potentially more selective antitumor therapies based on polymer technologies. Here, the basic principles for design of soluble polymeric drug delivery systems are explained and illustrated using examples drawn from our studies on the development of N-(2-hydroxypropyl)methacrylamide copolymer conjugates for use in cancer chemotherapy. Those soluble polymeric carriers that are undergoing clinical evaluation are briefly reviewed.
452 citations
TL;DR: In this paper, a Generalised Method of Moments estimator is used to estimate the tax incentives available to individual companies. But the effect of tax incentives on investment in UK companies is not explored.
416 citations
Journal Article•
TL;DR: The "enhanced permeability and retention effect" (EPR effect) has been studied extensively, and it is thought to constitute the mechanism of action of SMANCS (styrene-maleic/anhydride-neocarzinostatin), now in regular clinical use in Japan for the treatment of hepatoma.
Abstract: The biodistribution of soluble macromolecules is governed extensively by their ability to penetrate endothelial layers. Many solid tumors possess vasculature that is hyperpermeable to macromolecules, not always correlating with the presence of interendothelial cell fenestrations. The exact physiological mechanisms responsible for this nonspecific leakiness are not yet fully understood. Together with enhanced vascular permeability, however, tumors usually lack effective lymphatic drainage; consequently, they selectively accumulate circulating macromolecules (up to 10% of an i.v. dose per gram in mice). This "enhanced permeability and retention effect" (EPR effect) has been studied extensively, and it is thought to constitute the mechanism of action of SMANCS (styrene-maleic/anhydride-neocarzinostatin), now in regular clinical use in Japan for the treatment of hepatoma. It seems likely that EPR also contributes to the anticancer activity of the N-(2-hydroxypropyl)methacrylamide copolymer-anthracycline conjugates which are shortly to undergo clinical evaluation in the U.K.
334 citations
TL;DR: In this paper, a peatland hydrologic model predicted June - August decreases in water storage of between 82 and 144 mm, using as inputs increases in temperatures of 3 °C and rainfall of 1 mm d -, which translates into a water table drop relative to the peat surface, of between 14 and 22 cm, depending on whether the fen has a floating or non-floating surface.
Abstract: Methane flux from northern peatlands is believed to be an important contribution to the global methane budget. High latitude regions are predicted to experience significant changes in surface temperature and precipitation associated with the 2 × CO 2 climate scenarios, but the effects of these changes on methane emission are poorly understood. A peatland hydrologic model predicted June - August decreases in water storage of between 82 and 144 mm, using as inputs increases in temperatures of 3 °C and rainfall of 1 mm d - . These changes translate into a water table drop, relative to the peat surface, of between 14 and 22 cm, depending on whether the fen has a floating or non-floating surface. The 3 °C air temperature increase was predicted to raise peat temperature at 10 cm depth by 0.8 °C. These changes were then applied to relationships derived at a subarctic fen for water table: methane flux: temperature at 10 cm depth. Increased temperatures raise the methane flux by between 5 and 40%, but the lowered water table decreases methane flux by 74 and 81%, at the floating and nonfloating fen sites, respectively. These results suggest that methane emissions from northern peatlands are more sensitive to changes in moisture regime than temperature within the range of changes predicted for 2 × CO 2 scenarios. DOI: 10.1034/j.1600-0889.1992.t01-1-00002.x
315 citations
244 citations
TL;DR: In this article, the structural characterization of the low-temperature phases II-IV of the solid adduct from benzene and hexafluorobenzene was revealed by using a combination of powder diffraction techniques with neutrons and synchrotron radiation.
Abstract: Similarities with a number of liquid-crystal systems are revealed by the structural characterization of the low-temperature phases II-IV of the solid adduct from benzene and hexafluorobenzene (right). As the temperature is raised, increased rotation leads to a reduction in the interactions between neighboring columns of alternating C6H6 and C6F6 molecules. These results could only be obtained by using a combination of powder diffraction techniques with neutrons and synchrotron radiation.
229 citations
TL;DR: Some of the immunolabelled cell types described here are proposed as the origins of the similarly labelled puncta and fibres on the basis of known intrinsic connections.
Abstract: The distribution and colocalization of γ-aminobutyric acid (GABA)- and glycine-like immunoreactivity in the cochlear nuclear complex of the guinea pig have been studied to produce a light microscopic atlas. The method used was based on post-embedding immunocytochemistry in pairs of 0.5-μm-thick plastic sections treated with polyclonal antibodies against conjugated GABA and glycine respectively. Immunoreactive cells, presumably short axon neurones, predominated in the dorsal cochlear nucleus, with mostly single-GABA-labelled cells in the superficial layer, double-labelled in the middle, and single-glycine-labelled in the deep layers. A few large single-glycine-labelled cells, interpreted as commissural neurons, occurred in the ventral nucleus. Scattered double-labelled cells, probably Golgi cells, were seen in the granule cell domain. Immunolabelled puncta of all three staining categories occurred in large numbers throughout the complex, apposed to somata and in the neuropil, showing a differential distribution onto different types of neuron. Three immunolabelled tracts were noted: the tuberculoventral tract, the commissural acoustic stria, and the trapezoidal descending fibres. Most of the fibres in these tracts were single-labelled for glycine, although in the last mentioned tract single-GABA- and double-labelled fibres were also found. Some of the immunolabelled cell types described here are proposed as the origins of the similarly labelled puncta and fibres on the basis of known intrinsic connections.
226 citations
01 Jan 1992
202 citations
TL;DR: In this article, the authors used the William Herschel Telescope to find absorption features in V404 Cygni characteristic of a late G or early K star with a radial velocity curve of amplitude 211 ± 4km s−1 and period 6.473 ± 0.001 days.
Abstract: THE X-ray transient source GS2023 + 338 was discovered in out-burst by the Ginga satellite in 1989 (ref. 1) and has since been identified with the previously known recurrent nova V404 Cygni2. This system is recognized to be a low-mass X-ray binary3, with X-ray behaviour similar to black hole systems4, but attempts to deduce an orbital period from photometry5–9 and spectroscopy10,11 have yielded modulations with periods from 10 minutes to 6 hours. Two years after the outburst, we have used the William Herschel Telescope to find absorption features in V404 Cyg characteristic of a late G or early K star with a radial velocity curve of amplitude 211 ± 4km s−1 and period 6.473 ± 0.001 days. The deduced mass function of 6.26±0.31 M⊙ is a firm lower limit to the mass of the compact object, which for reasonable assumptions of orbital inclination and companion star mass must be a black hole with probable mass in the range 8–15.5 M⊙. We consider this the most persuasive case yet for the existence of a black hole.
TL;DR: These macromolecular produgs have the ability to concentrate drug in solid tumours, and with incorporation of targeting residues can promote organ-specific or tumour-specific uptake, and covalent conjugation markedly reduces all aspects of DOX-associated toxicity.
TL;DR: In this article, the authors show that the protection afforded by shrubs to the ground surface beneath them results in differential rainsplash, and that surface materials of small mounds have the same size distribution as sediment transported by rainfall.
TL;DR: The results from the first stage of an optical follow-up study of the X-ray brightest clusters of galaxies detected in the ROSAT All-Sky Survey (RASS) are presented in this article.
Abstract: The results from the first stage of an optical follow-up study of the X-ray brightest clusters of galaxies detected in the ROSAT All-Sky Survey (RASS) are presented. The redshifts of the central galaxies in 29 of the X-ray brightest Abell and Zwicky clusters in the RASS have been measured using the Faint Object Spectrograph on the Isaac Newton Telescope. Approximately 40 per cent of the central galaxy spectra obtained show strong optical line emission. In several cases this emission is quite spectacular
TL;DR: In this paper, a molecular dynamics simulation of the effects of mixed alkali cations on the structure of binary silicate glasses is presented, where the authors demonstrate that the alkalis segregate from the silicate network over distances of a few angstroms, and they suggest that stochastic mixing of alkalis nevertheless impedes the hopping process of a given alkali ion.
Abstract: MUCH is known about short-range (<5A) structural order in oxide glasses from experimental probes of local structure such as X-ray absorption fine structure (XAFS)1, but over the medium range (5-20 A) their structures are poorly understood. Computer simulations based on measured parameters for local atomic environments, however, can provide structural models on the nanometre scale, which enable dynamic properties such as ionic transport to be considered. Here we describe a molecular dynamics simulation of the effects of mixed alkali cations on the structure of binary silicate glasses. It is well known that the ionic conductivity of alkali glasses falls markedly when more than one alkali is present2. We demonstrate that the alkalis segregate from the silicate network over distances of a few angstroms. Although ionic mobility is expected to be higher in these microsegregated regions than in the surrounding silicate network, we suggest that stochastic mixing of alkalis nevertheless impedes the hopping process of a given alkali ion. This is manifest as an increase in the average activation energy for hopping and results in a lowering of the total ionic conductivity.
TL;DR: In this paper, the influence of dipolar interactions between the particles on the value of T g is discussed by considering the effects of particle interactions on the blocking temperature, and an effective blocking temperature model is developed.
TL;DR: It is concluded that the same neural mechanism determines aspect ratio discrimination threshold for rectangles and ellipses and that this mechanism is sensitive to aspect ratio independently of linear dimensions.
TL;DR: In this article, a shell model for calcite and aragonite has been developed using rigid-ion, two-body Born-type potentials, supplemented by O-C-O angular terms inside the CO3 groups.
Abstract: Calcite and aragonite have been modeled using rigid-ion, two-body Born-type potentials, supplemented by O-C-O angular terms inside the CO3 groups. A shell model has also been developed for calcite. Atomic charges, repulsive parameters and force constants have been optimized to reproduce the equilibrium crystal structures, the elastic constants and the Raman and infrared vibrational frequencies. The rigid-ion potential RIM (atomic charges: z(O) = -0.995 e, z(C) = 0.985 e, z(Ca) = 2.0 e) fitted to calcite properties is able to account for those of aragonite as well. Experimental unit-cell edges, elastic constants, internal and lattice frequencies are reproduced with average relative errors of 2.1, 5.5, 2.4, 15.1 % for calcite and of 0.2, 19.4, 2.5, 11.8 % for aragonite, respectively. The RIM potential is suitable for thermodynamic and phase diagram simulations in the CaCO3 system, and is discussed and compared to other potentials.
TL;DR: The study leads to the following conclusions: that the PASCAL database is representative, at least in the area of acidification research; that indexer bias is negligible; and that the co-word method satisfactorily identifies groups of research themes and the way in which these evolve.
Abstract: This paper extends the co-word method for mapping science, adopting new statistical and graphical methods to explore time-series data and the changing distribution of effort between different research themes. It also tests the reliability of the co-word method, comparing coword data on the acidification of the environment with data derived from a large scale interview study. Overall, the study increases our confidence in the reliability of the co-word method. In particular, it leads us to the following conclusions: (a) that the PASCAL database is representative, at least in the area of acidification research; (b) that indexer bias is negligible; and (c) that the co-word method satisfactorily identifies groups of research themes and the way in which these evolve.
TL;DR: Data are presented showing that, if the changes in the appearance of a scene were sufficiently great, subjects were capable of making the required discriminations highly reliably, and without scrutiny.
TL;DR: An algorithm for the automated analysis of lidar cloud returns has been developed and it has been found that the algorithm can handle the wide range of complex cloud situations encountered.
Abstract: An algorithm for the automated analysis of lidar cloud returns has been developed as part of the Experimental Cloud Lidar Pilot Study program. This automated method determines the cloud-base and cloud-top heights as well as the altitude of the maximum return signal. A large body of cloud data that were obtained at 532 and 1064 nm with a Nd:YAG lidar have been evaluated and it has been found that the algorithm can handle the wide range of complex cloud situations encountered. The need for a more careful definition of the cloud-base height and cloud-top height is described and discussed in relation to the existing measurements with rotating beam and laser ceilometers.
TL;DR: The calculated defect energies are shown to be in remarkably close agreement with experiment and with values obtained from empirical modeling.
Abstract: Ab initio total-energy calculations have been performed on a parallel computer to study the formation and migration energies of cation and anion vacancies in MgO. The calculations are made in the framework of density functional and pseudopotential theory, using the supercell method, with the valence orbitals expanded in plane waves. The relaxed ground state is determined by conjugate-gradients minimization of the total-energy functional with respect to the plane-wave coefficients of occupied orbitals. The calculated defect energies are shown to be in remarkably close agreement with experiment and with values obtained from empirical modeling. We present results for the electron distribution surrounding the vacancies that show that the distortion induced in the oxygen ions is more complex than has previously been thought.
TL;DR: Slow releasing ADR conjugates containing tripeptide spacers were most effective in increasing animal lifespan and Cytotoxicity measured in vitro did not correlate with the rate of drug release seen during incubation with papain and tritosomes.
TL;DR: All three simple methods for maintaining body temperature using the “kangaroo” method, the traditional “oil massage” or a “plastic swaddler” were found to be equally effective.
Abstract: A prospective observational study of post-delivery care and neonatal body temperature, carried out at Kathmandu Maternity Hospital, was followed by a randomized controlled intervention study using three simple methods for maintaining body temperature There were 500 infants in the initial observation study and 300 in the intervention study In the observation study, 85% (420/495) of infants had temperatures < 36 degrees C at 2 h and nearly 50% (198/405) had temperatures < 36 degrees C at 24 h (14% were < 35 degrees C) Most of the infants who were cold at 24 h had initially become cold at the time of delivery (only seven infants had been both well dried and wrapped) In the intervention study, all infants were dried and wrapped before random assignment to one of the three methods: the "kangaroo" method, the traditional "oil massage" or a "plastic swaddler" All three were found to be equally effective Overall, 38% (114/298) of the infants had temperatures < 36 degrees C at 2 h and 18% (41/231) at 24 h (when none was < 35 degrees C)
TL;DR: The post-war internationalization and globalization of production, finance and exchange has not been matched by a corresponding internationalization of political authority, especially with regard to economic matters as discussed by the authors.
TL;DR: Stretch-activated ion channels permeable to calcium are of particular interest in relation to tip growth and their concentration at the hyphal tip supports a direct role in the tip growth process.
Abstract: We have used the patch clamp technique to study ion channels involved in hyphal tip growth in the oomycete Saprolegnia ferax . The development of a technique in which protoplasts are produced in distinct linear arrays has permitted the study of transport proteins in protoplasts derived from different regions of the hypha. Using the cell-attached mode we find two K + channels of different amplitudes, both of which are activated by Ca 2+ , as shown by the addition of the Ca 2+ ionophore A23187. In nearly all the recordings (95%) there was a characteristic but variable oscillatory nature to the activity of these channels. K + fluxes through these channels are inward and are of a sufficient magnitude to have a significant impact on cell turgor. Hyphal tip, but rarely distal protoplasts, also contain two stretch-activated channels, one displaying larger amplitudes and permeable to both Ca 2+ and K + and a smaller channel permeable to Mg 2+ . Stretch-activated ion channels permeable to calcium are of particular interest in relation to tip growth and their concentration at the hyphal tip supports a direct role in the tip growth process. This represents a significant advance toward understanding the mechanisms of regulation of this mode of cellular growth.
TL;DR: Responses of the VPP suggest that its underlying physiological generators are sensitive to basic configurai properties of the visual stimulus; and also that face- and object-related information are processed in the same brain area(s), although not necessarily by the same physiological mechanisms.
Abstract: The influence of stimulus form on the scalp-recorded “vertex positive peak” (VPP) evoked by images of faces (Jeffreys 1989a) was studied in seven subjects In separate experiments, we recorded the responses to 2D images of: (1) many different depictions of human faces; (2) the heads of several different species; (3) many familiar non-face objects; and (4) stimuli where the configuration of objects were modified to produce an “illusory” or “non-contextual” subjective impression of a face The results showed that every facial representation, including the “illusory” stimuli, and most of the non-face objects, evoked a VPP of corresponding form and scalp distribution The object-evoked VPPs, however, were always smaller and usually later than those evoked by the faces VPPs of longer latency but often comparable amplitude were also recorded for impoverished compared to well-defined facial representations; and for most non-human compared to human faces Very consistent responses were recorded to repeated presentations of the same stimulus for the same subject, but there was considerable variation in latency as well as amplitude (but not form) of the VPP evoked under identical experimental conditions for different subjects These response properties of the VPP, suggest that its underlying physiological generators are sensitive to basic configurai properties of the visual stimulus; and also that face- and object-related information are processed in the same brain area(s), although not necessarily by the same physiological mechanisms
TL;DR: No overall significant difference was found between doctor-prescribed and patient-chosen regime, or between once- a-day and three-times-a-day dosage, and there was no evidence that better compliance produced a better therapeutic result.
Abstract: A total of 89 depressed out-patients were randomly allocated to one of three groups: group A received one dose of antidepressant medication at night; group B received three doses of medication during the day; group C were allowed to choose either A or B above. Compliance with medication was assessed at three, six, nine and 12 weeks by interrogation and pill count; at the same time, depression and side-effects were rated. No overall significant difference was found between doctor-prescribed and patient-chosen regime, or between once-a-day and three-times-a-day dosage. However, compliance was significantly better in those patients who were allowed to choose, when they selected the three-times-a-day regime. There was a significant decline in compliance for all regimes over the 12 weeks. There was no evidence that better compliance produced a better therapeutic result, and possible reasons are given for this finding.
01 Jan 1992
TL;DR: All-trans beta-carotene radical anion efficiently transfers an electron to oxygen but the reverse reaction is not observed and, instead, the formation of a beta- carotene-superoxide radical addition complex is suggested which may be related to the anti-cancer properties of these molecules.
Abstract: All-trans beta-carotene radical anion efficiently transfers an electron to oxygen but the reverse reaction is not observed and, instead we suggest the formation of a beta-carotene-superoxide radical addition complex. On the other hand, all-trans lycopene undergoes a reversible electron transfer with the superoxide radical. This distinctive behaviour may be related to the anti-cancer properties of these molecules.
TL;DR: In this paper, the authors examined what infants know about the attributes that distinguish people from things and concluded that the onset of this distinction begins early in life, even 2-month-old infants treat people and objects differently when confounding variables of stimuli are controlled.
Abstract: The ability to distinguish people from things sheds light on an important theoretical question: how is the development of social cognition related to the development of physical cognition? According to Piaget (1954), cognition is unitary and the processes used in dealing with the physical world are the same as those employed in the social world. This statement should be questioned. Although people and objects share certain fundamental properties (size, shape, etc.), only people can communicate, act independently and have feelings and intentions. Thus, people seem much more complex to deal with than things. If all cognitive development derives from the growth of a unitary system, then knowledge about animate objects should lag behind that of inanimate objects. The present paper explores this idea by examining what infants know about the attributes that distinguish people from things. It is concluded that the onset of this distinction begins early in life. Even 2-month-old infants treat people and objects differently when confounding variables of the stimuli are controlled. Rather than lagging behind, the infants' understanding of people appears precocious. The infants' recognition of the crucial distinction between the two classes suggests that a conceptual system is beginning to be formed soon after birth. This conceptual system appears different for social and non-social objects and serves as a foundation from which infants might come to understand the distinctive properties of animate and inanimate objects.