A note on commuting graphs for symmetric groups

The commuting graph C(G;X) , where G is a group and X a subset of G, has X as its vertex set with two distinct elements of X joined by an edge when they commute in G. Here the diameter and disc structure of C(G;X) is investigated when G is the symmetric group and X a conjugacy class of G

The Development of a Common Investment Appraisal for Urban Transport Projects.

In December 1990 we were invited by Birmingham City Council and Centro to submit a proposal for an introductory study of the development of a common investment appraisal for urban transport projects. Many of the issues had arisen during the Birmingham Integrated Transport Study (BITS) in which we were involved, and in the subsequent assessment of light rail schemes of which we have considerable experience. In subsequent discussion, the objectives were identified as being:- (i) to identify, briefly, the weaknesses with existing appraisal techniques; (ii) to develop proposals for common methods for the social cost-benefit appraisal of both urban road and rail schemes which overcome these weaknesses; (iii) to develop complementary and consistent proposals for common methods of financial appraisal of such projects; (iv) to develop proposals for variants of the methods in (ii) and (iii) which are appropriate to schemes of differing complexity and cost; (v) to consider briefly methods of treating externalities, and performance against other public sector goals, which are consistent with those developed under (ii) to (iv) above; (vi) to recommend work to be done in the second phase of the study (beyond March 1991) on the provision of input to such evaluation methods from strategic and mode-specific models, and on the testing of the proposed evaluation methods. Such issues are particularly topical at present, and we have been able to draw, in our study, on experience of:- (i) evaluation methods developed for BITS and subsequent integrated transport studies (MVA) (ii) evaluation of individual light rail and heavy rail investment projects (ITS,MVA); (iii) the recommendations of AMA in "Changing Gear" (iv) advice to IPPR on appraisal methodology (ITS); (v) submissions to the House of Commons enquiry into "Roads for the Future" (ITS); (vi) advice to the National Audit Office (ITS) (vii) involvement in the SACTRA study of urban road appraisal (MVA, ITS

Surface tension of the isotropic-nematic interface

We present the first calculations of the pressure tensor profile in the vicinity of the planar interface between isotropic liquid and nematic liquid crystal, using Onsager's density functional theory and computer simulation. When the liquid crystal director is aligned parallel to the interface, the situation of lowest free energy, there is a large tension on the nematic side of the interface and a small compressive region on the isotropic side. By contrast, for perpendicular alignment, the tension is on the isotropic side. There is excellent agreement between theory and simulation both in the forms of the pressure tensor profiles, and the values of the surface tension.Comment: Minor changes; to appear in Phys. Rev.

Transduction of a dominant-negative H-Ras into human eosinophils attenuates extracellular signal-regulated kinase activation and interleukin-5-mediated cell viability

Inhibition of eosinophil apoptosis by exposure to interleukin-5 (IL-5) is associated with the development of tissue eosinophilia and may contribute to the inflammation characteristic of asthma. Analysis of the signaling events associated with this process has been hampered by the inability to efficiently manipulate eosinophils by the introduction of active or inhibitory effector molecules. Evidence is provided, using a dominantnegative N17 H-Ras protein (dn-H-Ras) and MEK inhibitor U0126, that activation of the Ras-Raf-MEK-ERK pathway plays a determining role in the prolongation of eosinophil survival by IL-5. For these studies, a small region of the human immunodeficiency virus Tat protein, a protein transduction domain known to enter mammalian cells efficiently, was fused to the N-terminus of dn-H-Ras. The Tat-dn-HRas protein generated from this construct transduced isolated human blood eosinophils at more than 95% efficiency. When Tat-dn-H-Ras-transduced eosinophils were treated with IL-5, they exhibited a time- and dosage-dependent reduction in extracellular regulated kinase 1 and 2 activation and an inhibition of p90 Rsk1 phosphorylation and IL-5-mediated eosinophil survival in vitro. In contrast, Tat-dn-H-Ras did not inhibit CD11b upregulation or STAT5 tyrosine phosphorylation. These data demonstrate that Tat dominant-negative protein transduction can serve as an important and novel tool in studying primary myeloid cell signal transduction in primary leukocytes and can implicate the Ras-Raf-MEK-ERK pathway in IL-5-initiated eosinophil survival

An evaluation of the Wii Nunchuk as an alternative assistive device for people with intellectual and physical disabilities using switch controlled software

Many people with intellectual disabilities also have physical difficulties which prevent them from using standard computer control devices. Custom made alternative devices for those with special needs can be expensive and the low unit turnover makes the prospect unattractive to potential manufacturers. One solution is to explore the potential of devices used in contemporary gaming technology, such as the Nintendo Wii. The Wii Nunchuk has the potential to replace joystick functions with the advantages of not being surface bound and easier for some individuals to grasp. This study evaluated the feasibility of using the Nunchuk by comparing its performance as a switch with the participant's usual switch. Twenty three volunteers aged between 17 and 21 with intellectual and physical disabilities completed a Single Switch Performance Test using the new device and their familiar device. For most functions of the switch, there was no significant difference between the participants' performance using the Nunchuck and their familiar device. Additional analysis found that some participants' performance did improve whilst using the Nunchuck, but this was not significantly related to physical or cognitive ability. Those whose performance was better with the Nunchuk were more likely to hold it in the conventional way than were those who had better performance with their familiar device. This merits it being offered as a possible alternative to currently available switches for those with physical difficulties affecting their grip

Comparative flood damage model assessment: towards a European approach

There is a wide variety of flood damage models in use internationally, differing substantially in their approaches and economic estimates. Since these models are being used more and more as a basis for investment and planning decisions on an increasingly large scale, there is a need to reduce the uncertainties involved and develop a harmonised European approach, in particular with respect to the EU Flood Risks Directive. In this paper we present a qualitative and quantitative assessment of seven flood damage models, using two case studies of past flood events in Germany and the United Kingdom. The qualitative analysis shows that modelling approaches vary strongly, and that current methodologies for estimating infrastructural damage are not as well developed as methodologies for the estimation of damage to buildings. The quantitative results show that the model outcomes are very sensitive to uncertainty in both vulnerability (i.e. depth–damage functions) and exposure (i.e. asset values), whereby the first has a larger effect than the latter. We conclude that care needs to be taken when using aggregated land use data for flood risk assessment, and that it is essential to adjust asset values to the regional economic situation and property characteristics. We call for the development of a flexible but consistent European framework that applies best practice from existing models while providing room for including necessary regional adjustments

The nature of slow dynamics in a minimal model of frustration-limited domains

We present simulation results for the dynamics of a schematic model based on the frustration-limited domain picture of glass-forming liquids. These results are compared with approximate theoretical predictions analogous to those commonly used for supercooled liquid dynamics. Although model relaxation times increase by several orders of magnitude in a non-Arrhenius manner as a microphase separation transition is approached, the slow relaxation is in many ways dissimilar to that of a liquid. In particular, structural relaxation is nearly exponential in time at each wave vector, indicating that the mode coupling effects dominating liquid relaxation are comparatively weak within this model. Relaxation properties of the model are instead well reproduced by the simplest dynamical extension of a static Hartree approximation. This approach is qualitatively accurate even for temperatures at which the mode coupling approximation predicts loss of ergodicity. These results suggest that the thermodynamically disordered phase of such a minimal model poorly caricatures the slow dynamics of a liquid near its glass transition

Characterisation of strip silicon detectors for the ATLAS Phase-II Upgrade with a micro-focused X-ray beam

The planned HL-LHC (High Luminosity LHC) in 2025 is being designed to maximise the physics potential through a sizable increase in the luminosity up to 6 · 1034 cm−2 s −1 . A consequence of this increased luminosity is the expected radiation damage at 3000 fb−1 after ten years of operation, requiring the tracking detectors to withstand fluences to over 1 · 1016 1 MeV neq/cm2 . In order to cope with the consequent increased readout rates, a complete re-design of the current ATLAS Inner Detector (ID) is being developed as the Inner Tracker (ITk). Two proposed detectors for the ATLAS strip tracker region of the ITk were characterized at the Diamond Light Source with a 3 µm FWHM 15 keV micro focused X-ray beam. The devices under test were a 320 µm thick silicon stereo (Barrel) ATLAS12 strip mini sensor wire bonded to a 130 nm CMOS binary readout chip (ABC130) and a 320 µm thick full size radial (end-cap) strip sensor - utilizing bi-metal readout layers - wire bonded to 250 nm CMOS binary readout chips (ABCN-25). A resolution better than the inter strip pitch of the 74.5 µm strips was achieved for both detectors. The effect of the p-stop diffusion layers between strips was investigated in detail for the wire bond pad regions. Inter strip charge collection measurements indicate that the effective width of the strip on the silicon sensors is determined by p-stop regions between the strips rather than the strip pitch