On quaternionic functional analysis

In this article, we will show that the category of quaternion vector spaces, the category of (both one-sided and two sided) quaternion Hilbert spaces and the category of quaternion $B^*$-algebras are equivalent to the category of real vector spaces, the category of real Hilbert spaces and the category of real $C^*$-algebras respectively. We will also give a Riesz representation theorem for quaternion Hilbert spaces and will extend two results of Kulkarni (namely, we will give the full versions of the Gelfand-Naimark theorem and the Gelfand theorem for quaternion $B^*$-algebras). On our way to these results, we compare, clarify and unify the term "quaternion Hilbert spaces" in the literatures.Comment: to appear in the Mathematical Proceedings of the Cambridge Philosophical Societ

Dilepton Production in e−pe^- p and e+e−e^+ e^- Colliders

In an $e^- p$ collider, a striking signature for a dilepton gauge boson is \ep \ ; this cross-section is calculated by using the helicity amplitude technique. At HERA, with center-of-mass energy $\sqrt s = 314 GeV$, a dilepton mass above $150 GeV$ is inaccessible but at LEPII-LHC, with a center-of-mass energy $\sqrt s = 1790 GeV$, masses up to 650 GeV can be discovered. In an $e^+ e^-$ collider, the signature is \ee \ . The cross-sections of this process are also calculated for the center-of-mass energies $\sqrt s = 200, 500$ and $1000 GeV$.Comment: 16 pages, 3 figures (not included), IFP-428-UN

3-Meth­oxy-N-p-tolyl­benzohydroxamic acid

Two mol­ecules of the title compound, C15H15NO3, are linked by a pair of O—H⋯Ocarbon­yl hydrogen bonds over a centre of inversion to form a hydrogen-bonded dimer. With respect to the –C(=O)—N(OH)– unit, the methoxy-substituted ring is twisted by 42.2 (1)°, whereas the methyl-substituted ring is twisted by 52.2 (1)°

The Scalar Sector of 3-3-1 Models

We study the mass spectrum and the eigenstates of the scalar sectors in 3-3-1 models. We show that, in one of the models, the physical scalar masses lead to theoretical constraints to the vacuum expectation values. The models allow very light Higgs bosons. One of the neutral scalars can be identified with the standard model one.Comment: 14 pages, Revtex 3.0, four figures available upon reques

Health and safety of the older worker

This is the author's pre-copyedited accepted manuscript. The final published article is available from the link below. Copyright @ 2012 The Authors.Background - In the UK, increasing numbers of paid employees are over 60 years with further increases expected as the state pension age rises. Some concern surrounds possible increased work-related illness and accidents for people working beyond the age of 60. Aims - To identify the available evidence for health and safety risks of workers over age 60 years with respect to factors associated with injuries and accidents. Methods - Databases searched included PUBMED, OSHUpdate, National Institute for Occupational Safety and Health (NIOSHTIC-2), SafetyLit, the UK The Health and Safety Executive (HSELINE) and the Canadian Centre for Occupational Health and Safety until December 2009. Inclusion criteria were workers aged over 60 years. Findings were grouped into occupational accidents and injuries and individual and workplace factors that may have influenced risk of injury to the over-60s. Results - Very little direct evidence was found concerning safety practices and health risks of workers over age 60. Some safety risks were associated with specific physical declines such as age-related hearing loss. Overall, these workers had fewer accidents and injuries but these were more likely to be serious or fatal when they occurred. There was no strong evidence that work patterns, including shift work or overtime, affected safety. Protective, compensatory strategies or experience may maintain safe working practices. Conclusions - Implications for health and safety risks cannot be assessed without longitudinal research on workforces with substantial numbers of workers over age 60 in order to address the healthy worker effect.Institution of Occupational Health and Safet

pyPcazip: A PCA-based toolkit for compression and analysis of molecular simulation data

AbstractThe biomolecular simulation community is currently in need of novel and optimised software tools that can analyse and process, in reasonable timescales, the large generated amounts of molecular simulation data. In light of this, we have developed and present here pyPcazip: a suite of software tools for compression and analysis of molecular dynamics (MD) simulation data. The software is compatible with trajectory file formats generated by most contemporary MD engines such as AMBER, CHARMM, GROMACS and NAMD, and is MPI parallelised to permit the efficient processing of very large datasets. pyPcazip is a Unix based open-source software (BSD licenced) written in Python

A Dimensionality Reduction-Based Multi-Step Clustering Method for Robust Vessel Trajectory Analysis

The Shipboard Automatic Identification System (AIS) is crucial for navigation safety and maritime surveillance, data mining and pattern analysis of AIS information have attracted considerable attention in terms of both basic research and practical applications. Clustering of spatio-temporal AIS trajectories can be used to identify abnormal patterns and mine customary route data for transportation safety. Thus, the capacities of navigation safety and maritime traffic monitoring could be enhanced correspondingly. However, trajectory clustering is often sensitive to undesirable outliers and is essentially more complex compared with traditional point clustering. To overcome this limitation, a multi-step trajectory clustering method is proposed in this paper for robust AIS trajectory clustering. In particular, the Dynamic Time Warping (DTW), a similarity measurement method, is introduced in the first step to measure the distances between different trajectories. The calculated distances, inversely proportional to the similarities, constitute a distance matrix in the second step. Furthermore, as a widely-used dimensional reduction method, Principal Component Analysis (PCA) is exploited to decompose the obtained distance matrix. In particular, the top k principal components with above 95% accumulative contribution rate are extracted by PCA, and the number of the centers k is chosen. The k centers are found by the improved center automatically selection algorithm. In the last step, the improved center clustering algorithm with k clusters is implemented on the distance matrix to achieve the final AIS trajectory clustering results. In order to improve the accuracy of the proposed multi-step clustering algorithm, an automatic algorithm for choosing the k clusters is developed according to the similarity distance. Numerous experiments on realistic AIS trajectory datasets in the bridge area waterway and Mississippi River have been implemented to compare our proposed method with traditional spectral clustering and fast affinity propagation clustering. Experimental results have illustrated its superior performance in terms of quantitative and qualitative evaluation

Low- and High-Drag Intermittencies in Turbulent Channel Flows

Recent direct numerical simulations (DNS) and experiments in turbulent channel flow have found intermittent low- and high-drag events in Newtonian fluid flows, at Reτ=uτh/ν between 70 and 100, where uτ, h and ν are the friction velocity, channel half-height and kinematic viscosity, respectively. These intervals of low-drag and high-drag have been termed “hibernating” and “hyperactive”, respectively, and in this paper, a further investigation of these intermittent events is conducted using experimental and numerical techniques. For experiments, simultaneous measurements of wall shear stress and velocity are carried out in a channel flow facility using hot-film anemometry (HFA) and laser Doppler velocimetry (LDV), respectively, for Reτ between 70 and 250. For numerical simulations, DNS of a channel flow is performed in an extended domain at Reτ = 70 and 85. These intermittent events are selected by carrying out conditional sampling of the wall shear stress data based on a combined threshold magnitude and time-duration criteria. The use of three different scalings (so-called outer, inner and mixed) for the time-duration criterion for the conditional events is explored. It is found that if the time-duration criterion is kept constant in inner units, the frequency of occurrence of these conditional events remain insensitive to Reynolds number. There exists an exponential distribution of frequency of occurrence of the conditional events with respect to their duration, implying a potentially memoryless process. An explanation for the presence of a spike (or dip) in the ensemble-averaged wall shear stress data before and after the low-drag (or high-drag) events is investigated. During the low-drag events, the conditionally-averaged streamwise velocities get closer to Virk’s maximum drag reduction (MDR) asymptote, near the wall, for all Reynolds numbers studied. Reynolds shear stress (RSS) characteristics during these conditional events are investigated for Reτ = 70 and 85. Except very close to the wall, the conditionally-averaged RSS is higher than the time-averaged value during the low-drag events.</jats:p