Exact approximation of Rao-Blackwellised particle filters

Particle methods are a category of Monte Carlo algorithms that have become popular for performing inference in non-linear non-Gaussian state-space models. The class of 'Rao-Blackwellised' particle filters exploits the analytic marginalisation that is possible for some state- space models to reduce the variance of the Monte Carlo estimates. Despite being applicable to only a restricted class of state-space models, such as conditionally linear Gaussian models, these algorithms have found numerous applications. In scenarios where no such analytical integration is possible, it has recently been proposed in Chen et al. [2011] to use 'local' particle filters to carry out this integration numerically. We propose here an alternative approach also relying on \local" particle filters which is more broadly applicable and has attractive theoretical properties. Proof-of-concept simulation results are presented

Exploring Attitudes towards Genetically Modified Foods: Is there a Connection between People who are Concerned About the Environment and their Attitudes towards GM Foods

Genetically modified (GM) foods provide many advantages to modern agriculture, such as increased yields due to insect and pathogen resistance, productivity improvements, and offer a potential solution to address world hunger. However, GM foods have the potential to cause serious environmental harm, triggering public attitudes towards them to be divided. People are often suspicious of genetic modification, which may inhibit future development and adoption. This study considers GM foods, and aims to explore attitudes towards them, testing the hypotheses that people who are concerned about the environment are less likely to favour GM foods. Data collected through an online questionnaire, yielding 214 responses, is used to correlate environmental concern with attitudes towards GM foods, represented by a GM score. The data shows that total green score correlated against GM score showed a significant, but weak correlation. However, there were clear signs of heteroscedasticity in the data, showing that more environmentally concerned individuals show a greater variation in their attitude towards GM foods. Age also affected attitudes towards GM foods, with individuals between 46 and 60 being more likely to be against GM foods. The data shows that respondents’ main hesitations towards GM foods resulted from insufficient knowledge on the subject, concern over corporations using them for personal gain, and the uncertainty of the long-term effects on human and environmental health. If GM is to be used as part of the solution to sustainable food production, more emphasis is required on educating individuals on GM foods, their uses and future impacts

Lax Operator for the Quantised Orthosymplectic Superalgebra U_q[osp(2|n)]

Each quantum superalgebra is a quasi-triangular Hopf superalgebra, so contains a \textit{universal $R$-matrix} in the tensor product algebra which satisfies the Yang-Baxter equation. Applying the vector representation $\pi$, which acts on the vector module $V$, to one side of a universal $R$-matrix gives a Lax operator. In this paper a Lax operator is constructed for the $C$-type quantum superalgebras $U_q[osp(2|n)]$. This can in turn be used to find a solution to the Yang-Baxter equation acting on $V \otimes V \otimes W$ where $W$ is an arbitrary $U_q[osp(2|n)]$ module. The case $W=V$ is included here as an example.Comment: 15 page

Characterisation of damage mechanisms in oxide ceramics indented at dynamic and quasi-static strain rates

Ceramic materials are known to display rate dependent behaviour under impact. Tests to establish the strain-rate dependent variations in damage mechanisms have been carried out on debased alumina, an alumina-zirconia composite, and 3Y-TZP. Materials were indented dynamically and quasi-statically using identical sharp hardened steel projectiles while recording the load profile. Characteristics typical of both sharp and blunt indentation types were observed using scanning electron microscopy and piezospectroscopic mapping. At dynamic strain rates both the depth of the indentation and the residual stress in the material were lower than for quasi-static tests. This was attributed to temperature-induced softening of the projectile. Unusual behaviour was observed in the 3Y-TZP samples due to the reversible transformation from tetragonal to monoclinic crystal structures during mechanical loading. These effects and the observed superior mechanical strength against impact suggest that zirconia or zirconia-composite materials may have advantages over debased alumina for application as ceramic armour materials

Gate-To-Gate Life-Cycle Inventory of Laminated Veneer Lumber Production

A life-cycle inventory (LCI) study is conducted of laminated veneer lumber (LVL) manufacturing. This gate-to-gate study includes all environmental impacts from the logs to produce either veneer or parallel laminated veneer (PLV) as input to the LVL process, through production of the LVL. The study includes all materials, fuels, and electricity inputs to produce LVL and related co-products and emissions. The input and site emissions data were collected through surveys of manufacturing facilities in the Pacific Northwest and the Southeast regions of the U.S. SimaPro software, a program to conduct life-cycle inventory studies, is used to process the data and measure environmental impacts in terms of material use and emissions. The data are allocated on a mass basis to LVL based on their contribution to the mass sum of all product and co-products produced in manufacturing. All data are provided on a production unit basis of 1000 m3 and 1000 ft3 (MCF). In addition to the LCI data, carbon flow data are also given. These data are publicly available through reports, this publication, and the U.S. LCI Database Project. The data are useful forgenerating cradle-to-gate product LCIs when combined with the LCIs to produce logs as input to the plants and the transportation impacts to deliver materials. The data are useful as a benchmark for assessing process performance, for conducting life-cycle assessments of structural assemblies and the shell of residential and light commercial buildings

Measuring the effect of enhanced cleaning in a UK hospital : a prospective cross-over study

Increasing hospital-acquired infections have generated much attention over the last decade. There is evidence that hygienic cleaning has a role in the control of hospital-acquired infections. This study aimed to evaluate the potential impact of one additional cleaner by using microbiological standards based on aerobic colony counts and the presence of Staphylococcus aureus including meticillin-resistant S. aureus. We introduced an additional cleaner into two matched wards from Monday to Friday, with each ward receiving enhanced cleaning for six months in a cross-over design. Ten hand-touch sites on both wards were screened weekly using standardised methods and patients were monitored for meticillin-resistant S. aureus infection throughout the year-long study. Patient and environmental meticillin-resistant S. aureus isolates were characterised using molecular methods in order to investigate temporal and clonal relationships. Enhanced cleaning was associated with a 32.5% reduction in levels of microbial contamination at handtouch sites when wards received enhanced cleaning (P < 0.0001: 95% CI 20.2%, 42.9%). Near-patient sites (lockers, overbed tables and beds) were more frequently contaminated with meticillin-resistant S. aureus/S. aureus than sites further from the patient (P = 0.065). Genotyping identified indistinguishable strains from both handtouch sites and patients. There was a 26.6% reduction in new meticillin-resistant S. aureus infections on the wards receiving extra cleaning, despite higher meticillin-resistant S. aureus patient-days and bed occupancy rates during enhanced cleaning periods (P = 0.032: 95% CI 7.7%, 92.3%). Adjusting for meticillin-resistant S. aureus patient-days and based upon nine new meticillin-resistant S. aureus infections seen during routine cleaning, we expected 13 new infections during enhanced cleaning periods rather than the four that actually occurred. Clusters of new meticillin-resistant S. aureus infections were identified 2 to 4 weeks after the cleaner left both wards. Enhanced cleaning saved the hospital £30,000 to £70,000.Introducing one extra cleaner produced a measurable effect on the clinical environment, with apparent benefit to patients regarding meticillin-resistant S. aureus infection. Molecular epidemiological methods supported the possibility that patients acquired meticillin-resistant S. aureus from environmental sources. These findings suggest that additional research is warranted to further clarify the environmental, clinical and economic impact of enhanced hygienic cleaning as a component in the control of hospital-acquired infection

New hyper-Kaehler manifolds by fixing monopoles

The construction of new hyper-Kaehler manifolds by taking the infinite monopole mass limit of certain Bogomol'nyi-Prasad-Sommerfield monopole moduli spaces is considered. The one-parameter family of hyperkaehler manifolds due to Dancer is shown to be an example of such manifolds. A new family of fixed monopole spaces is constructed. They are the moduli spaces of four SU(4) monopoles, in the infinite mass limit of two of the monopoles. These manifolds are shown to be nonsingular when the fixed monopole positions are distinct.Comment: Version in Phys. Rev. D. 11 pp, RevTeX, 14 Postscript diagram