Showing papers by "University of Sussex published in 2006"

Cosmological constraints from the SDSS luminous red galaxies

Abstract: We measure the large-scale real-space power spectrum P(k) using luminous red galaxies (LRGs) in the Sloan Digital Sky Survey (SDSS) and use this measurement to sharpen constraints on cosmological parameters from the Wilkinson Microwave Anisotropy Probe (WMAP). We employ a matrix-based power spectrum estimation method using Pseudo-Karhunen-Loeve eigenmodes, producing uncorrelated minimum-variance measurements in 20 k-bands of both the clustering power and its anisotropy due to redshift-space distortions, with narrow and well-behaved window functions in the range 0.01h/Mpc 0.1h/Mpc and associated nonlinear complications, yet agree well with more aggressive published analyses where nonlinear modeling is crucial.

Improved experimental limit on the electric dipole moment of the neutron.

Abstract: An experimental search for an electric dipole moment (EDM) of the neutron has been carried out at the Institut Laue-Langevin, Grenoble. Spurious signals from magnetic-field fluctuations were reduced to insignificance by the use of a cohabiting atomic-mercury magnetometer. Systematic uncertainties, including geometric-phase-induced false EDMs, have been carefully studied. The results may be interpreted as an upper limit on the neutron EDM of |dn|

Cognitive Linguistics: An Introduction

Abstract: A general introduction to the area of theoretical linguistics known as cognitive linguistics, this textbook provides up-to-date coverage of all areas of the field, including recent developments within cognitive semantics (such as Primary Metaphor Theory, Conceptual Blending Theory, and Principled Polysemy), and cognitive approaches to grammar (such as Radical Construction Grammar and Embodied Construction Grammar). The authors offer clear critical evaluations of competing formal approaches within theoretical linguistics. For example, cognitive linguistics is compared to Generative Grammar and Relevance Theory. In the selection of material and in the presentations the authors have aimed for a balanced perspective. Part II, Cognitive Semantics, and Part III, Cognitive Approaches to Grammar, have been created to be read independently. The authors have kept in mind that different instructors and readers will need to use the book in different ways tailored to their own goals. The coverage is suitable for a number of courses. While all topics are presented in terms accessible to both undergraduate and graduate students of linguistics, cognitive linguistics, psycholinguistics, cognitive science, and modern languages, this work is sufficiently comprehensive and detailed to serve as a reference work for scholars who wish to gain a better understanding of cognitive linguistics.

The fourth data release of the Sloan Digital Sky Survey

Abstract: This paper describes the Fourth Data Release of the Sloan Digital Sky Survey (SDSS), including all survey-quality data taken through 2004 June. The data release includes five-band photometric data for 180 million objects selected over 6670 deg2 and 673,280 spectra of galaxies, quasars, and stars selected from 4783 deg2 of those imaging data using the standard SDSS target selection algorithms. These numbers represent a roughly 27% increment over those of the Third Data Release; all the data from previous data releases are included in the present release. The Fourth Data Release also includes an additional 131,840 spectra of objects selected using a variety of alternative algorithms, to address scientific issues ranging from the kinematics of stars in the Milky Way thick disk to populations of faint galaxies and quasars.

Cavity quantum electrodynamics

Abstract: This paper reviews the work on cavity quantum electrodynamics of free atoms. In recent years, cavity experiments have also been conducted on a variety of solid-state systems resulting in many interesting applications, of which microlasers, photon bandgap structures and quantum dot structures in cavities are outstanding examples. Although these phenomena and systems are very interesting, discussion is limited here to free atoms and mostly single atoms because these systems exhibit clean quantum phenomena and are not disturbed by a variety of other effects. At the centre of our review is the work on the one-atom maser, but we also give a survey of the entire field, using free atoms in order to show the large variety of problems dealt with. The cavity interaction can be separated into two main regimes: the weak coupling in cavity or cavity-like structures with low quality factors Q and the strong coupling when high-Q cavities are involved. The weak coupling leads to modification of spontaneous transitions and level shifts, whereas the strong coupling enables one to observe a periodic exchange of photons between atoms and the radiation field. In this case, atoms and photons are entangled, this being the basis for a variety of phenomena observed, some of them leading to interesting applications in quantum information processing. The cavity experiments with free atoms reached a new domain with the advent of experiments in the visible spectral region. A review on recent achievements in this area is also given.

Getting a grip on tangible interaction: a framework on physical space and social interaction

Abstract: Our current understanding of human interaction with hybrid or augmented environments is very limited. Here we focus on 'tangible interaction', denoting systems that rely on embodied interaction, tangible manipulation, physical representation of data, and embeddedness in real space. This synthesis of prior 'tangible' definitions enables us to address a larger design space and to integrate approaches from different disciplines. We introduce a framework that focuses on the interweaving of the material/physical and the social, contributes to understanding the (social) user experience of tangible interaction, and provides concepts and perspectives for considering the social aspects of tangible interaction. This understanding lays the ground for evolving knowledge on collaboration-sensitive tangible interaction design. Lastly, we analyze three case studies, using the framework, thereby illustrating the concepts and demonstrating their utility as analytical tools.

The sloan digital sky survey quasar survey: Quasar luminosity function from data release 3

Abstract: We determine the number counts and z = 0-5 luminosity function for a well-defined, homogeneous sample of quasars from the Sloan Digital Sky Survey (SDSS). We conservatively define the most uniform statistical sample possible, consisting of 15,343 quasars within an effective area of 1622 deg2 that was derived from a parent sample of 46,420 spectroscopically confirmed broad-line quasars in the 5282 deg2 of imaging data from SDSS Data Release 3. The sample extends from i = 15 to 19.1 at z 3 and to i = 20.2 for z 3. The number counts and luminosity function agree well with the results of the Two Degree Field QSO Redshift Survey (2QZ) at redshifts and luminosities at which the SDSS and 2QZ quasar samples overlap, but the SDSS data probe to much higher redshifts than does the 2QZ sample. The number density of luminous quasars peaks between redshifts 2 and 3, although uncertainties in the selection function in this range do not allow us to determine the peak redshift more precisely. Our best-fit model has a flatter bright-end slope at high redshift than at low redshift. For z < 2.4 the data are best fit by a redshift-independent slope of ? = -3.1 [?(L) ? L?]. Above z = 2.4 the slope flattens with redshift to ? -2.37 at z = 5. This slope change, which is significant at the 5 ? level, must be accounted for in models of the evolution of accretion onto supermassive black holes.

Networked control system: a brief survey

Abstract: A survey on networked control systems (NCSs), published in a previous paper, is updated and extended. A simple framework and some general formulations for the study of NCSs are proposed. In addition to the survey on NCSs, the impact of NCSs on traditional large-scale system control methodologies with a related application is also reviewed.

Targeting C-reactive protein for the treatment of cardiovascular disease

Abstract: Complement-mediated inflammation exacerbates the tissue injury of ischaemic necrosis in heart attacks and strokes, the most common causes of death in developed countries. Large infarct size increases immediate morbidity and mortality and, in survivors of the acute event, larger non-functional scars adversely affect long-term prognosis. There is thus an important unmet medical need for new cardioprotective and neuroprotective treatments. We have previously shown that human C-reactive protein (CRP), the classical acute-phase protein that binds to ligands exposed in damaged tissue and then activates complement1, increases myocardial and cerebral infarct size in rats subjected to coronary or cerebral artery ligation, respectively2, 3. Rat CRP does not activate rat complement, whereas human CRP activates both rat and human complement4. Administration of human CRP to rats is thus an excellent model for the actions of endogenous human CRP2, 3. Here we report the design, synthesis and efficacy of 1,6-bis(phosphocholine)-hexane as a specific small-molecule inhibitor of CRP. Five molecules of this palindromic compound are bound by two pentameric CRP molecules, crosslinking and occluding the ligand-binding B-face of CRP and blocking its functions. Administration of 1,6-bis(phosphocholine)-hexane to rats undergoing acute myocardial infarction abrogated the increase in infarct size and cardiac dysfunction produced by injection of human CRP. Therapeutic inhibition of CRP is thus a promising new approach to cardioprotection in acute myocardial infarction, and may also provide neuroprotection in stroke. Potential wider applications include other inflammatory, infective and tissue-damaging conditions characterized by increased CRP production, in which binding of CRP to exposed ligands in damaged cells may lead to complement-mediated exacerbation of tissue injury.

The role of double-strand break repair - insights from human genetics

Abstract: The efficient repair of DNA double-strand breaks is crucial in safeguarding the genomic integrity of organisms. Responses to double-strand breaks include complex signal-transduction, cell-cycle-checkpoint and repair pathways. Defects in these pathways lead to several human disorders with pleiotropic clinical features. Dissection of the molecular basis that underlies the diverse clinical features is enhancing our understanding of the damage-response mechanisms and their role in development, and might ultimately facilitate treatment.

Learning to Adapt: Organisational Adaptation to Climate Change Impacts

Abstract: Analysis of human adaptation to climate change should be based on realistic models of adaptive behaviour at the level of organisations and individuals. The paper sets out a framework for analysing adaptation to the direct and indirect impacts of climate change in business organisations with new evidence presented from empirical research into adaptation in nine case-study companies. It argues that adaptation to climate change has many similarities with processes of organisational learning. The paper suggests that business organisations face a number of obstacles in learning how to adapt to climate change impacts, especially in relation to the weakness and ambiguity of signals about climate change and the uncertainty about benefits flowing from adaptation measures. Organisations rarely adapt ‘autonomously’, since their adaptive behaviour is influenced by policy and market conditions, and draws on resources external to the organisation. The paper identifies four adaptation strategies that pattern organisational adaptive behaviour.

University Patenting and its Effects on Academic Research: the Emerging European Evidence

Abstract: This paper surveys the existing fragmentary data on the growth of university-owned patents and university-invented patents in Europe. We find evidence that university patenting is growing, but this phenomenon remains heterogeneous across countries and disciplines. We found some evidence that university licensing is not profitable for most universities, although some do succeed in attracting substantial additional revenues. This might be due to the fact that patents and publications tend to go hand in hand. In a dynamic setting however, we fear that the increase in university patenting exacerbates differences across universities in terms of financial resources and research outcome.

Observation of muon neutrino disappearance with the MINOS detectors in the NuMI neutrino beam

Abstract: This letter reports results from the MINOS experiment based on its initial exposure to neutrinos from the Fermilab NuMI beam. The rate and energy spectra of charged current muon neutrino interactions are compared in two detectors located along the beam axis at distances of 1 km and 735 km. With 1.27 x 10^{20} 120 GeV protons incident on the NuMI target, 215 events with energies below 30 GeV are observed at the Far Detector, compared to an expectation of 336 \\\\\\\\\\\\\\\\pm 14.4 events. The data are consistent with muon neutrino disappearance via oscillation with |\\\\\\\\\\\\\\\\Delta m^2_{23}| = 2.74^{+0.44}_{-0.26} x 10^{-3} eV^2/c^4 and sin^2(2\\\\\\\\\\\\\\\\theta_{23}) > 0.87 (at 60% C.L.).

“Making it real”: exploring the potential of augmented reality for teaching primary school science

Abstract: The use of augmented reality (AR) in formal education could prove a key component in future learning environments that are richly populated with a blend of hardware and software applications. However, relatively little is known about the potential of this technology to support teaching and learning with groups of young children in the classroom. Analysis of teacher–child dialogue in a comparative study between use of an AR virtual mirror interface and more traditional science teaching methods for 10-year-old children, revealed that the children using AR were less engaged than those using traditional resources. We suggest four design requirements that need to be considered if AR is to be successfully adopted into classroom practice. These requirements are: flexible content that teachers can adapt to the needs of their children, guided exploration so learning opportunities can be maximised, in a limited time, and attention to the needs of institutional and curricular requirements.

Profiles of children with specific reading comprehension difficulties

Abstract: Background. Children with fluent and accurate word reading in the presence of poor text comprehension are impaired on a wide range of reading-related tasks. Aims. This study investigated the consistency of skill impairment in a sample of poor comprehenders to identify any fundamental skill weakness that (i) might be associated with poor text comprehension, and (ii) might lead to depressed reading development. An additional aim was to determine whether reading comprehension difficulties are associated with more general educational difficulties. Sample. Twenty-three poor comprehenders and 23 good comprehenders with age appropriate word reading accuracy were assessed when aged 8 years. Concurrent reading and language performance and reading, educational attainment and reasoning skills 3 years later are reported. Methods. The following skills were assessed when aged 8 years: word reading, text comprehension, vocabulary, syntax, cognitive ability, working memory, comprehension subskills. Listening comprehension, SAT scores and reasoning scores at 11 years are also reported. Results. There was no evidence for any fundamental skill weaknesses in the population of poor comprehenders at Time 1. However, poor vocabulary skills led to impaired growth in word reading ability and poor general cognitive ability led to impaired growth in comprehension. Poor comprehenders obtained lower SAT scores than did the good comprehenders at 11 years. Conclusions. These findings indicate that a single underlying source of poor comprhension is unlikely. Poor comprehenders are at risk of generally poor educational attainment, although weak verbal or cognitive skills appear to affect the reading development of poor comprehenders in different ways.

The SCUBA Half-Degree Extragalactic Survey – II. Submillimetre maps, catalogue and number counts

Abstract: We present maps, source catalogue and number counts of the largest, most complete and unbiased extragalactic submillimetre survey: the 850-μm SCUBA Half-Degree Extragalactic Survey (SHADES). Using the Submillimetre Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT), SHADES mapped two separate regions of sky: the Subaru/XMM–Newton Deep Field (SXDF) and the Lockman Hole East (LH). Encompassing 93 per cent of the overall acquired data (i.e. data taken up to 2004 February 1), these SCUBA maps cover 720 arcmin2 with a rms noise level of about 2 mJy and have uncovered >100 submillimetre galaxies. In order to ensure the utmost robustness of the resulting source catalogue, data reduction was independently carried out by four subgroups within the SHADES team, providing an unprecedented degree of reliability with respect to other SCUBA catalogues available from the literature. Individual source lists from the four groups were combined to produce a robust 120-object SHADES catalogue; an invaluable resource for follow-up campaigns aiming to study the properties of a complete and consistent sample of submillimetre galaxies. For the first time, we present deboosted flux densities for each submillimetre galaxy found in a large survey. Extensive simulations and tests were performed separately by each group in order to confirm the robustness of the source candidates and to evaluate the effects of false detections, completeness and flux density boosting. Corrections for these effects were then applied to the data to derive the submillimetre galaxy source counts. SHADES has a high enough number of detected sources that meaningful differential counts can be estimated, unlike most submillimetre surveys which have to consider integral counts. We present differential and integral source number counts and find that the differential counts are better fit with a broken power law or a Schechter function than with a single power law; the SHADES data alone significantly show that a break is required at several mJy, although the precise position of the break is not well constrained. We also find that a 850-μm survey complete down to 2 mJy would resolve 20–30 per cent of the far-infrared background into point sources.

Changing Children's Intergroup Attitudes Toward Refugees: Testing Different Models of Extended Contact

Abstract: The present research evaluated an intervention, derived from the "extended contact hypothesis," which aimed to change children's intergroup attitudes toward refugees. The study (n=253) tested 3 models of extended contact among 5- to 11-year-old children: dual identity, common ingroup identity, and decategorization. Children read friendship stories based upon these models featuring in- and outgroup members. Outgroup attitudes were significantly more positive in the extended contact conditions, compared with the control, and this was mediated by "inclusion of other in self." The dual identity intervention was the most effective extended contact model at improving outgroup attitudes. The effect of condition on outgroup intended behavior was moderated by subgroup identity. Implications for theoretically based prejudice-reduction interventions among children are discussed.

The Second Release of the RASP System

Abstract: We describe the new release of the RASP (robust accurate statistical parsing) system, designed for syntactic annotation of free text. The new version includes a revised and more semantically-motivated output representation, an enhanced grammar and part-of-speech tagger lexicon, and a more flexible and semi-supervised training method for the structural parse ranking model. We evaluate the released version on the WSJ using a relational evaluation scheme, and describe how the new release allows users to enhance performance using (in-domain) lexical information.

The distribution of fitness effects of new deleterious amino acid mutations in humans

Abstract: The distribution of fitness effects of new mutations is a fundamental parameter in genetics. Here we present a new method by which the distribution can be estimated. The method is fairly robust to changes in population size and admixture, and it can be corrected for any residual effects if a model of the demography is available. We apply the method to extensively sampled single-nucleotide polymorphism data from humans and estimate the distribution of fitness effects for amino acid changing mutations. We show that a gamma distribution with a shape parameter of 0.23 provides a good fit to the data and we estimate that >50% of mutations are likely to have mild effects, such that they reduce fitness by between one one-thousandth and one-tenth. We also infer that <15% of new mutations are likely to have strongly deleterious effects. We estimate that on average a nonsynonymous mutation reduces fitness by a few percent and that the average strength of selection acting against a nonsynonymous polymorphism is ~9 × 10-5. We argue that the relaxation of natural selection due to modern medicine and reduced variance in family size is not likely to lead to a rapid decline in genetic quality, but that it will be very difficult to locate most of the genes involved in complex genetic diseases.

ATR‐dependent phosphorylation and activation of ATM in response to UV treatment or replication fork stalling

Abstract: The phosphatidyl inositol 3-kinase-like kinases (PIKKs), ataxia-telangiectasia mutated (ATM) and ATM- and Rad3-related (ATR) regulate parallel damage response signalling pathways. ATM is reported to be activated by DNA double-strand breaks (DSBs), whereas ATR is recruited to single-stranded regions of DNA. Although the two pathways were considered to function independently, recent studies have demonstrated that ATM functions upstream of ATR following exposure to ionising radiation (IR) in S/G2. Here, we show that ATM phosphorylation at Ser1981, a characterised autophosphorylation site, is ATR-dependent and ATM-independent following replication fork stalling or UV treatment. In contrast to IR-induced ATM-S1981 phosphorylation, UV-induced ATM-S1981 phosphorylation does not require the Nbs1 C-terminus or Mre11. ATR-dependent phosphorylation of ATM activates ATM phosphorylation of Chk2, which has an overlapping function with Chk1 in regulating G2/M checkpoint arrest. Our findings provide insight into the interplay between the PIKK damage response pathways.

The neurodegenerative disease protein aprataxin resolves abortive DNA ligation intermediates

Abstract: Ataxia oculomotor apraxia-1 (AOA1) is a neurological disorder caused by mutations in the gene (APTX) encoding aprataxin1, 2. Aprataxin is a member of the histidine triad (HIT) family of nucleotide hydrolases and transferases3, and inactivating mutations are largely confined to this HIT domain. Aprataxin associates with the DNA repair proteins XRCC1 and XRCC4, which are partners of DNA ligase III and ligase IV, respectively4, 5, 6, 7, suggestive of a role in DNA repair. Consistent with this, APTX-defective cell lines are sensitive to agents that cause single-strand breaks and exhibit an increased incidence of induced chromosomal aberrations4, 5, 8. It is not, however, known whether aprataxin has a direct or indirect role in DNA repair, or what the physiological substrate of aprataxin might be. Here we show, using purified aprataxin protein and extracts derived from either APTX-defective chicken DT40 cells or Aptx-/- mouse primary neural cells, that aprataxin resolves abortive DNA ligation intermediates. Specifically, aprataxin catalyses the nucleophilic release of adenylate groups covalently linked to 5'-phosphate termini at single-strand nicks and gaps, resulting in the production of 5'-phosphate termini that can be efficiently rejoined. These data indicate that neurological disorders associated with APTX mutations may be caused by the gradual accumulation of unrepaired DNA strand breaks resulting from abortive DNA ligation events.

Bottlenecks and broomsticks: the molecular evolution of Mycobacterium bovis

Abstract: Mycobacterium bovis is the cause of tuberculosis in cattle and is a member of the Mycobacterium tuberculosis complex. In contrast to many other pathogenic bacterial species, there is little evidence for the transfer and recombination of genes between cells. The clonality of this group of organisms indicates that the population structure is dominated by reductions in diversity, caused either by population bottlenecks or selective sweeps as entire chromosomes become fixed in the population. We describe how these forces have shaped not only the phylogeny of this group but also, at a very local level, the population structure of Mycobacterium bovis in the British Isles. We also discuss the practical implications of applying this knowledge to understanding the spread of infection and the development of improved vaccines and diagnostic tests

Participatory Mapping and Geographic Information Systems: Whose Map? Who is Empowered and Who Disempowered? Who Gains and Who Loses?

Abstract: In recent years, changes in participatory methodologies (PMs) may have been even more rapid than those in spatial technologies. Local people's abilities to make maps only became widely known and facilitated in the early 1990s. Participatory mapping has spread like a pandemic with many variants and applications not only in natural resource management but also in many other domains. With mapping as one element, there are now signs of a new pluralist eclecticism and creativity in PMs. The medium and means of mapping, whether ground, paper or GIS and the style and mode of facilitation, influence who takes part, the nature of outcomes and power relationships. Much depends on the behaviour and attitudes of facilitators and who controls the process. Many ethical issues present troubling dilemmas, and lead to overarching questions about empowerment and ownership. Questions to be asked, again and again, are: Who is empowered and who disempowered? And, who gains and who loses?