Arguing Using Opponent Models

Peer reviewedPostprin

Location-based mobile phone applications for increasing student engagement with field-based extra-curricular activities

With pressures on university and student finance, and an ever-growing number of internet-enabled portable devices, we investigate the ability for free, ‘self-guided’ field-trips – using Global Positioning Systems (GPS) features present on most modern smartphones, combined with internet access to provide background information and receive responses from participants. We create a field-trip around Cheltenham, to examine rock types commonly used for buildings. Student motivation to complete the extra-curricular task was reasonable, with 50% of students participating. However, few thought their geological knowledge had improved. We suggest that, as well as some minor technological issues, the potential use of mobile internet and apps for teaching in Higher Education may have been overestimated (especially since motivation will decrease with novelty of the use of the technology). However, we acknowledge these conclusions are based only on a small pilot study. This may be related to how people in general, and students in particular, use mobile technology: instant bite-sized knowledge conflicting with the deep learning required for Higher Education

Reproductive Isolation in a Threespine Stickleback Hybrid Zone

In many estuarine sites, morphological and genetic differences between anadromous and freshwater threespine sticklebacks are maintained despite breeding in sympatry. Here, we investigate the maintenance of this morphological divergence in a natural hybrid zone in the River Tyne, Scotland. We provide a morphological description of the hybrid zone, and using a Bayesian MCMC approach, identified distinct anadromous and freshwater genetic clusters. Anadromous and freshwater sticklebacks breed in spatial and temporal sympatry in the lower reaches of the River Tyne. The frequency of hybrids within these sites (33%) indicates prezygotic isolation is not complete, and suggests that assortative mating is not strong. However, significant heterozygote deficit and cytonuclear disequilibrium in juveniles collected from sympatric sites confirms that barriers to gene flow exist between the morphs in the wild. In addition, we found no evidence of a directional bias in hybridisation, although hybrids with anadromous mothers were more common because anadromous females outnumbered freshwater females within the hybrid zone. We discuss the potential contribution of temporal, spatial, and sexual prezygotic barriers to the observed reproductive isolation as well as postzygotic selection against hybrid zygotes or fry

Cost and performance of some carbon capture technology options for producing different quality CO₂ product streams

A techno-economic assessment of power plants with CO2 capture technologies with a focus on process scenarios that deliver different grades of CO2 product purity is presented. The three leading CO2 capture technologies are considered, namely; oxyfuel combustion, pre-combustion and post-combustion capture. The study uses a combination of process simulation of flue gas cleaning processes, modelling with a power plant cost and performance calculator and literature values of key performance criteria in order to evaluate the performance, cost and CO2 product purity of the considered CO2 capture options. For oxyfuel combustion capture plants, three raw CO2 flue gas processing strategies of compression and dehydration only, double flash system purification and distillation purification are considered. Analysis of pre-combustion capture options is based on integrated gasification combined cycle plants using physical solvent systems for capturing CO2 and sulfur species via three routes; co-capture of sulfur impurities with the CO2 stream using Selexol™ solvent, separate capture of CO2 and sulfur impurities using Selexol™, and Rectisol® solvent systems for separate capture of sulfur impurities and CO2. Analysis of post-combustion capture plants was made with and without some conventional pollution control devices. The results highlight the wide variation in CO2 product purity for different oxyfuel combustion capture scenarios and the wide cost variation for the pre-combustion capture scenarios. The post-combustion capture plant with conventional pollution control devices offers high CO2 purity (99.99 mol%) for average cost of considered technologies. The calculations performed will be of use in further analyses of whole chain CCS for the safe and economic capture, transport and storage of CO2

Intravenous thrombolysis may not improve clinical outcome of acute ischemic stroke patients without a baseline vessel occlusion

Background and Purpose: The benefit of thrombolysis in ischemic stroke patients without a visible vessel occlusion still requires investigation. This study tested the hypothesis that non-lacunar stroke patients with no visible vessel occlusion on baseline imaging would have a favorable outcome regardless of treatment with alteplase. Methods: We utilized a prospectively collected registry of ischemic stroke patients [the International Stroke Perfusion Imaging Registry (INSPIRE)] who had baseline computed tomographic perfusion and computed tomographic angiography. The rates of patients achieving modified Rankin Scale (mRS) 0-1 were compared between alteplase treated and untreated patients using logistic regression to generate odds ratios. Results: Of 1569 patients in the INSPIRE registry, 1,277 were eligible for inclusion. Of these, 306 (24%) had no identifiable occlusion and were eligible for alteplase, with 141 (46%) of these patients receiving thrombolysis. The treated and untreated groups had significantly different median baseline National Institutes of Health Stroke Scale (NIHSS) [alteplase 8, interquartile range (IQR) 5-10, untreated 6, IQR 4-8, P < 0.001] and median volume of baseline perfusion lesion [alteplase 5.6 mL, IQR 1.3-17.7 mL, untreated 2.6 mL, IQR 0-6.7 mL, P < 0.001]. After propensity analysis, alteplase treated patients without a vessel occlusion were less likely to have an excellent outcome (mRS 0-1; 56%) than untreated (78.8%, OR, 0.42, 95% confidence interval, 0.24-0.75, P = 0.003). Conclusions: In this non-randomized comparison, alteplase treatment in patients without an identifiable vessel occlusion did not result in higher rates of favorable outcome compared to untreated. However, treated patients displayed less favorable baseline prognostic factors than the untreated group. Further studies may be required to confirm this data.Huiqiao Tian, Mark W. Parsons, Christopher R. Levi, Xin Cheng, Richard I. Aviv, Neil J. Spratt, Timothy J. Kleinig, Billy O'Brien, Kenneth S. Butcher, Longting Lin, Jingfen Zhang, Qiang Dong, Chushuang Chen and Andrew Bivar

A new measurement of direct CP violation in two pion decays of the neutral kaon

The NA48 experiment at CERN has performed a new measurement of direct CP violation, based on data taken in 1997 by simultaneously collecting K_L and K_S decays into pi0pi0 and pi+pi-. The result for the CP violating parameter Re(epsilon'/epsilon) is (18.5 +/- 4.5(stat)} +/- 5.8 (syst))x10^{-4}.Comment: 18 pages, 6 figure

Observation of hard scattering in photoproduction events with a large rapidity gap at HERA

Events with a large rapidity gap and total transverse energy greater than 5 GeV have been observed in quasi-real photoproduction at HERA with the ZEUS detector. The distribution of these events as a function of the $\gamma p$ centre of mass energy is consistent with diffractive scattering. For total transverse energies above 12 GeV, the hadronic final states show predominantly a two-jet structure with each jet having a transverse energy greater than 4 GeV. For the two-jet events, little energy flow is found outside the jets. This observation is consistent with the hard scattering of a quasi-real photon with a colourless object in the proton.Comment: 19 pages, latex, 4 figures appended as uuencoded fil

Search for the standard model Higgs boson in tau final states

We present a search for the standard model Higgs boson using hadronically decaying tau leptons, in 1 inverse femtobarn of data collected with the D0 detector at the Fermilab Tevatron ppbar collider. We select two final states: tau plus missing transverse energy and b jets, and tau+ tau- plus jets. These final states are sensitive to a combination of associated W/Z boson plus Higgs boson, vector boson fusion and gluon-gluon fusion production processes. The observed ratio of the combined limit on the Higgs production cross section at the 95% C.L. to the standard model expectation is 29 for a Higgs boson mass of 115 GeV.Comment: publication versio

Measurement of the ttbar Production Cross Section in ppbar Collisions at sqrt{s} = 1.96 TeV using Kinematic Characteristics of Lepton + Jets Events

We present a measurement of the top quark pair ttbar production cross section in ppbar collisions at a center-of-mass energy of 1.96 TeV using 230 pb**{-1} of data collected by the DO detector at the Fermilab Tevatron Collider. We select events with one charged lepton (electron or muon), large missing transverse energy, and at least four jets, and extract the ttbar content of the sample based on the kinematic characteristics of the events. For a top quark mass of 175 GeV, we measure sigma(ttbar) = 6.7 {+1.4-1.3} (stat) {+1.6- 1.1} (syst) +/-0.4 (lumi) pb, in good agreement with the standard model prediction.Comment: submitted to Phys.Rev.Let

Measurement of the ttbar Production Cross Section in ppbar Collisions at sqrt(s)=1.96 TeV using Lepton + Jets Events with Lifetime b-tagging

We present a measurement of the top quark pair ($t\bar{t}$) production cross section ($\sigma_{t\bar{t}}$) in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV using 230 pb$^{-1}$ of data collected by the D0 experiment at the Fermilab Tevatron Collider. We select events with one charged lepton (electron or muon), missing transverse energy, and jets in the final state. We employ lifetime-based b-jet identification techniques to further enhance the $t\bar{t}$ purity of the selected sample. For a top quark mass of 175 GeV, we measure $\sigma_{t\bar{t}}=8.6^{+1.6}_{-1.5}(stat.+syst.)\pm 0.6(lumi.)$ pb, in agreement with the standard model expectation.Comment: 7 pages, 2 figures, 3 tables Submitted to Phys.Rev.Let