Numerical Simulation and Optimisation of a Gas-Solid-Liquid Separator

Imperial Users onl

An economic approach to collective management of endemic animal diseases

The control of animal diseases is an issue of particular interest in animal production chains. Because of their direct impact on production, animal diseases generate income shortfalls for farmers. In some cases, diseases may also have lead to human health problems and undermine market access conditions. Because of these potential negative impacts, some diseases are regulated. But for many communicable diseases, much latitude is given to individual control of the disease by farmers. In the case of a communicable disease, individual management therefore generates an externality, as individual decisions have an impact on the level of risk exposure of other farms to the disease. Thus, the collective result of individual management may differ from the collective expectations. This gap can be reduced by collective actions. The aim of this paper is to provide a conceptual framework for the study of collective management of animal diseases, which will provide management tools to collective managers of animal health. The development of this conceptual framework rests on three steps. We first discuss the means to model the individual decisions of farmer in regard to animal diseases. Then it should take into account the interaction between the epidemiology of the disease and the individual decisions of farmers, by the coupling of epidemiologic and economic models. Finally, collective management tools are introduced in these models in order to test incentives schemes for horizontal coordination. Finally, collective actions are introduced in these models, in order to test devices for horizontal coordination (management of prevalence between farms).Animal health economics - Micro modelling – Bio-economic modelling - endemic animal diseases, Animal health economics, Micro modelling, Bio-economic modelling, endemic animal diseases, Livestock Production/Industries,

Solving the "Isomorphism of Polynomials with Two Secrets" Problem for all Pairs of Quadratic Forms

We study the Isomorphism of Polynomial (IP2S) problem with m=2 homogeneous quadratic polynomials of n variables over a finite field of odd characteristic: given two quadratic polynomials (a, b) on n variables, we find two bijective linear maps (s,t) such that b=t . a . s. We give an algorithm computing s and t in time complexity O~(n^4) for all instances, and O~(n^3) in a dominant set of instances. The IP2S problem was introduced in cryptography by Patarin back in 1996. The special case of this problem when t is the identity is called the isomorphism with one secret (IP1S) problem. Generic algebraic equation solvers (for example using Gr\"obner bases) solve quite well random instances of the IP1S problem. For the particular cyclic instances of IP1S, a cubic-time algorithm was later given and explained in terms of pencils of quadratic forms over all finite fields; in particular, the cyclic IP1S problem in odd characteristic reduces to the computation of the square root of a matrix. We give here an algorithm solving all cases of the IP1S problem in odd characteristic using two new tools, the Kronecker form for a singular quadratic pencil, and the reduction of bilinear forms over a non-commutative algebra. Finally, we show that the second secret in the IP2S problem may be recovered in cubic time

Accuracy of mobile digital teledermoscopy for skin self-examinations in adults at high risk of skin cancer: an open-label, randomised controlled trial

Background: Skin self-examinations supplemented with mobile teledermoscopy might improve early detection of skin cancers compared with naked-eye skin self-examinations. We aimed to assess whether mobile teledermoscopy-enhanced skin self-examination can improve sensitivity and specificity of self-detection of skin cancers when compared with naked-eye skin self-examination. Methods: This randomised, controlled trial was done in Brisbane (QLD, Australia). Eligible participants (aged ≥18 years) had at least two skin cancer risk factors as self-reported in the eligibility survey and had to own or have access to an iPhone compatible with a dermatoscope attachment (iPhone versions 5–8). Participants were randomly assigned (1:1), via a computer-generated randomisation procedure, to the intervention group (mobile dermoscopy-enhanced self-skin examination) or the control group (naked-eye skin self-examination). Control group and intervention group participants received web-based instructions on how to complete a whole body skin self-examination. All participants completed skin examinations at baseline, 1 month, and 2 months; intervention group participants submitted photographs of suspicious lesions to a dermatologist for telediagnosis after each skin examination and control group participants noted lesions on a body chart that was sent to the research team after each skin examination. All participants had an in-person whole-body clinical skin examination within 3 months of their last skin self-examination. Primary outcomes were sensitivity and specificity of skin self-examination, patient selection of clinically atypical lesions suspicious for melanoma or keratinocyte skin cancers (body sites examined, number of lesions photographed, types of lesions, and lesions missed), and diagnostic concordance of telediagnosis versus in-person whole-body clinical skin examination diagnosis. All primary outcomes were analysed in the modified intention-to-treat population, which included all patients who had a clinical skin examination within 3 months of their last skin self-examination. This trial was registered with the Australian and New Zealand Clinical Trials Registry, ACTRN12616000989448. Findings: Between March 6, 2017, and June 7, 2018, 234 participants consented to enrol in the study, of whom 116 (50%) were assigned to the intervention group and 118 (50%) were assigned to the control group. 199 participants (98 participants in the intervention group and 101 participants in the control group) attended the clinical skin examination and thus were eligible for analyses. Participants in the intervention group submitted 615 lesions (median 6·0 per person; range 1–24) for telediagnosis and participants in the control group identified and recorded 673 lesions (median 6·0 per person; range 1–16). At the lesion level, sensitivity for lesions clinically suspicious for skin cancer was 75% (95% CI 63–84) in the intervention group and 88% (95% CI 80–91) in the control group (p=0·04). Specificity was 87% (95% CI 85–90) in the intervention group and 89% (95% CI 87–91) in the control group (p=0·42). At the individual level, the intervention group had a sensitivity of 87% (95% CI 76–99) compared with 97% (95% CI 91–100) in the control group (p=0·26), and a specificity of 95% (95% CI 90–100) compared with 96% (95% CI 91–100) in the control group. The overall diagnostic concordance between the telediagnosis and in-person clinical skin examination was 88%. Interpretation: The use of mobile teledermoscopy did not increase sensitivity for the detection of skin cancers compared with naked-eye skin self-examination; thus, further evidence is necessary for inclusion of skin self-examination technology for public health benefit. Funding: National Health and Medical Research Council (Australia)

Self-Assessed Health Status and Satisfaction with Health Care Services in the Context of the Enlarged European Union

The paper aims at analysing the relationship between self-rated health-status, satisfaction with health care services and socio-economic factors, in the context of different national health care systems in the enlarged European Union. The effects of socio-economic deprivation and the functioning of national health care systems on self-rated health status and satisfaction with health care services are investigated using the European Social Survey 2006 dataset (ESS3), and macro data provided by Eurostat (2007) and the World Health Organization (2007). Socio-economic deprivation is measured both at the micro-level (using indicators of economic strain, household income, education, employment status and belonging to discriminated groups), and the macro-level (national poverty rates, the values of poverty thresholds, quintile ratios and GDP per capita). The performance of national health care systems is quantified with the help of two indexes, designed for the purpose of the present study: an index of total health care provisions and an index of governmental commitment to health care. The following countries are included in the analysis: Belgium, Bulgaria, Denmark, Finland, France, Germany, Hungary, Poland, Portugal, Romania, Slovenia, Slovakia, Spain, Sweden, and the United Kingdom.self-assessed health ; health care systems ; health inequalities ; governmental policies

Acoustic damping in Li2_2O-2B2_2O3_3 glass observed by inelastic x-ray and optical Brillouin scattering

The dynamic structure factor of lithium-diborate glass has been measured at several values of the momentum transfer $Q$ using high resolution inelastic x-ray scattering. Much attention has been devoted to the low $Q$-range, below the observed Ioffe-Regel crossover \qco{}$\simeq$ 2.1 nm$^{-1}$. We find that below \qco{}, the linewidth of longitudinal acoustic waves increases with a high power of either $Q$, or of the frequency $\Omega$, up to the crossover frequency \OMco{} $\simeq$ 9 meV that nearly coincides with the center of the boson peak. This new finding strongly supports the view that resonance and hybridization of acoustic waves with a distribution of rather local low frequency modes forming the boson peak is responsible for the end of acoustic branches in strong glasses. Further, we present high resolution Brillouin light-scattering data obtained at much lower frequencies on the same sample. These clearly rule out a simple $\Omega^2$-dependence of the acoustic damping over the entire frequency range.Comment: 5 pages, 5 figures, submitted to the proceedings of IDMRCS 2005, Lille, Franc

Slider-Block Friction Model for Landslides: Application to Vaiont and La Clapiere Landslides

Accelerating displacements preceding some catastrophic landslides have been found empirically to follow a time-to-failure power law, corresponding to a finite-time singularity of the velocity $v \sim 1/(t_c-t)$ [{\it Voight}, 1988]. Here, we provide a physical basis for this phenomenological law based on a slider-block model using a state and velocity dependent friction law established in the laboratory and used to model earthquake friction. This physical model accounts for and generalizes Voight's observation: depending on the ratio $B/A$ of two parameters of the rate and state friction law and on the initial frictional state of the sliding surfaces characterized by a reduced parameter $x_i$, four possible regimes are found. Two regimes can account for an acceleration of the displacement. We use the slider-block friction model to analyze quantitatively the displacement and velocity data preceding two landslides, Vaiont and La Clapi\`ere. The Vaiont landslide was the catastrophic culmination of an accelerated slope velocity. La Clapi\`ere landslide was characterized by a peak of slope acceleration that followed decades of ongoing accelerating displacements, succeeded by a restabilizing phase. Our inversion of the slider-block model on these data sets shows good fits and suggest to classify the Vaiont (respectively La Clapi\`ere) landslide as belonging to the velocity weakening unstable (respectively strengthening stable) sliding regime.Comment: shortened by focusing of the frictional model, Latex document with AGU style file of 14 pages + 11 figures (1 jpeg photo of figure 6 given separately) + 1 tabl

Paid Work and Intellectual Disability

Adults with intellectual disabilities in paid work have voiced a number of concerns regarding their employment: independence at work, the continued need for links with formal support, choices in lifestyle opportunities and lack of career path options. In a central New Zealand region selected agencies were asked to identify adults with intellectual disabilities who had paid work. The agencies then forwarded invitations to adults whom they considered were successfully employed. Seventeen workers responded and were interviewed on how they obtained and learned their job and the initial and on-going support they received. If permissions were gained from both parties then important other persons/s were also interviewed. As a result of this survey strategies leading to better opportunities and greater employment rates for adults with intellectual disabilities are offered

Copulas and Correlation in Statistical Risk Theory

The Financial Risk Management (FRM) aims to identify, measure and manage risks in different sectors. One of the core things during such operations is measuring different dependencies. Linear correlation is known as one of the most popular measure of dependence, however it is known that it is a reasonable mea- sure of dependence only when variables are Normally distributed, but this is not the case with credit and portfolio risks, therefore other measures of dependency are needed. This paper presents a Copula function for bivariate case as one of the tools to analyze dependencies in portfolio risk management. Copulas were first introduced by Sklar in 1959 [8], and in 1999 they were studied in financial context for the first time by Embrechts et al. in 1999 [4]. Motivated by the copula analysis of European stock portfolios [6], this paper aims to analyze portfolio consisting of Asian S&P Asia 50 and S&P BSE 100 indices, and apply copula to this portfolio