Quantitative risk assessment of Campylobacter in broiler chickens – Assessing interventions to reduce the level of contamination at the end of the rearing period

The European Food Safety Authority (EFSA) has estimated that a proportion ranging from 20% to 30% of campylobacteriosis in humans may be attributed to the consumption of broiler meat and a reduction in the numbers of Campylobacter in the intestines of infected birds at slaughter by 3 log units would reduce the public health risk by at least 90%. In this study, a stochastic model was implemented to reproduce the dynamics of Campylobacter transmission in broiler flocks and explore the effects of several management conditions and/or on-farm mitigation strategies on the estimated level of contamination of infected flocks at slaughter. Results were expressed as ‘proportion of highly contaminated flocks’ (%HCFs) and estimated as a function of the proportion of infected birds in the flock the day of final depopulation and the individual level of contamination in infected birds. The effects of the mitigation strategies aimed at reducing the level of contamination in infected birds were modelled assuming that those effects are exerted on the distribution describing the bacterial load in infected birds. The impact of management conditions such as the adoption of enhanced biosecurity measures (B+) and/or partial depopulation during the production cycle (T+) were quantified using results of an extensive epidemiological study conducted in UK. A standard broiler flock was reproduced and used as baseline to make comparisons and simulate the effects of the mitigation strategies of interest. The baseline model predicted 18.8% probability of HCFs at slaughter. A positive effect ranging from −32.44% to −4.78% was attributed to B+ while T+ had negative effect ranging from +17.55% to +86.70%. When both the effects were tested simultaneously (B+T+), results were not conclusive with %HCFs ranging from −20.21% to +77.65%. When mitigation strategies operating on Campylobacter concentration in intestine were tested, a reduction of 100% and 99.6% in %HFCs were estimated following a generic treatment with bacteriocins and bacteriophages. Reduction in %HCFs as a function of immunization measures were explored and a reduction of 15% in the rate of transmission led to a %HCFs at slaughter reduced by almost 50%. The model was developed to be flexible, easily reproducible, updatable and adaptable to several baseline scenarios. The main parameters and assumptions underlying the baseline model were tested and a sensitivity analysis was performed to identify and discuss the impact that the uncertainty in the baseline information might have on the outcomes.     

Correlation of critical heat flux for flow boiling of water in mini-channels

In view of practical significance of a correlation of critical heat flux (CHF) in the aspects of engineering design and prediction, this study is aiming at evaluation of existing CHF correlations for flow boiling of water with available databases taken from small-diameter tubes, and then development of a new, simple CHF correlation. Available CHF databases in the literature for flow boiling of water in small-diameter tubes (0.33 < D_h < 6.22 mm) are collected, covering wide parametric ranges. Three correlations by Bowring, Katto and Shah are evaluated with the CHF data for saturated flow boiling, and three correlations by Inasaka–Nariai, Celata et al. and Hall–Mudawar evaluated with the CHF data for subcooled flow boiling. The Hall–Mudawar correlation and the Shah correlation seem to be the most reliable tools for CHF prediction in the subcooled and saturated flow boiling regions, respectively. In order to avoid the defect of predictive discontinuities often encountered when applying previous correlations, a simple, nondimensional, inlet conditions dependent CHF correlation for saturated flow boiling has been formulated. Its functional form is determined by the application of the artificial neural network and parametric trend analyses to the collected database. Superiority of this correlation has been verified by the database. The new correlation has a mean deviation of 16.8% for this collected databank, smallest among all tested correlations. Compared to many inordinately complex correlations, this new correlation consists only of a single equation.     

Chirp Control of an Electroabsorption Modulator to be used for Regeneration and Wavelength Conversion at 40 Gbit/s in All-Optical Networking

Chirp control to produce low or negative values of chirp at the output of an electroabsorption modulator (EAM) is an important mechanism for reducing the signal degradation due to chromatic dispersion in high-speed transmission over standard single-mode fibre. An analytical model for the chirp performance of an EAM capable of optical regeneration and simultaneous wavelength conversion operating at 40 Gbit/s is derived. A chirp control approach is identified using this model by exploring the tradeoff between the α-parameter describing the chirp factor (based on the nonlinear absorption coefficients) and bias voltage requirements of an EAM. In particular, an optimum range of bias voltage is determined to ensure reduced chirp operation when a two-tone signal (i.e., comprised of bias and modulating voltages) is applied to the EAM. It is also demonstrated for large signal operation at 40 Gbit/s that the optimum range of reverse bias voltage is between 0 and 2 V to obtain low values for the chirp factor (between +1 and −2) in order to facilitate the necessary chirp control in all-optical networking. In addition, it is identified that at 40 Gbit/s higher positive values of the second- and third- order nonlinear coefficients of chirp must be avoided when operating at reverse bias voltages less than 1 V.     

A Novel Method for the Diagnosis of the Incipient Faults in Analog Circuits Based on LDA and HMM

Diagnosis of incipient faults for electronic systems, especially for analog circuits, is very important, yet very difficult. The methods reported in the literature are only effective on hard faults, i.e., short-circuit or open-circuit of the components. For a soft fault, the fault can only be diagnosed under the occurrence of large variation of component parameters. In this paper, a novel method based on linear discriminant analysis (LDA) and hidden Markov model (HMM) is proposed for the diagnosis of incipient faults in analog circuits. Numerical simulations show that the proposed method can significantly improve the recognition performance. First, to include more fault information, three kinds of original feature vectors, i.e., voltage, autoregression-moving average (ARMA), and wavelet, are extracted from the analog circuits. Subsequently, LDA is used to reduce the dimensions of the original feature vectors and remove their redundancy, and thus, the processed feature vectors are obtained. The LDA is further used to project three kinds of the processed feature vectors together, to obtain the hybrid feature vectors. Finally, the hybrid feature vectors are used to form the observation sequences, which are sent to HMM to accomplish the diagnosis of the incipient faults. The performance of the proposed method is tested, and it indicates that the method has better recognition capability than the popularly used backpropagation (BP) network.     

Technique for finding and identifying filters that cut off OTDR lights in front of ONU from a central office

We report on a newly developed in-service measurement technique that can be used from a central office to find and identify any filter in front of an ONU on an optical fiber access network. Using this system, in-service tests can be performed because the test lights are modulated at a high frequency. Moreover, by using the equipment we developed, this confirmation operation can be performed continuously and automatically with existing automatic fiber testing systems. The developed technique is effective for constructing a fiber line testing system with an optical time domain reflectometer.     

Space,Politics and Desire: Configuring the Landscape in Post-Revolutionary France

The French Revolution radically reconfigured citizens' views of both real and imagined space. This article sets out to explore this process of reconfiguration and the relationship between politics and space from the period immediately before the French Revolution in 1789 to the collapse of the Empire in 1815 and its aftermath. Although the liberties brought about by the Revolution made access to space one of its defining characteristics, the spaces of the Revolution were characterized by a diversity in which each political constituency made a space of its own choosing. Those spaces took forms as diverse as the pastoral garden, tales of devil abduction, political festivals, space travel, and hallucinatory visions of Jean-Jacques Rousseau's Switzerland. It was only when Napoléon ‘terminated’ the Revolution in 1799 that space was given a rational, homotopic shape, a shape that endured until the imperatives of the Bourbon Restoration required another configuration.     

Chemometrics and intelligent laboratory systems: Information for authors

Research papers and reviews begin with an abstract (50–250 words) which should compromise a brief factual account of the contents of the paper, with emphasis on new information. Abbreviations, jargon and reference numbers must not be used. The abstract should be suitable for use by abstracting services without rewriting.     

Survey of deflection limits for portal frames in Australia

The design of portal frames can often be governed by deflection limits and it is therefore important that any deflection limits be realistic. Most current codes of practice do not provide mandatory deflection limits, preferring instead to leave them to the judgement of the designer.The authors, through the Australian Institute of Steel Construction, have recently conducted a survey among practising engineers of deflection limits for industrial buildings. Although the results of the survey have been reported,¹ it is thought that the results will be of interest to international readers, and so the findings are presented in this paper.The results of the survey show some diversity of opinion among designers. Nevertheless, recommendations for deflection limits are made.     

Calibration of the charm fine-grained calorimeter

Calorimeters have been used extensively for the study of neutrino interactions in the last decade. This paper describes the need for calibration of such calorimeters and how this was realized for the case of the CHARM fine-grained calorimeter. The energy and spatial response of the calorimeter to both hadronic and electromagnetic showers was measured in π and electron beams from 5 to 140 GeV. The results and resolutions are presented.     

Structure for user-oriented dialogues in computer-aided telephony

Members of The Speech Project, at Oxford Brookes University, have been experimenting with alternative structures for ‘goal-seeking’ dialogues. A dialogue prototyping system has been developed that can instantiate different dialogue structures kept on file. These become active after being installed using dynamic data structures. Input is achieved using speech recognition for a small range of words, and output is in the form of pre-recorded speech messages. The dialogues thus created employ a new approach, and replace the usual menustructure with a simpler question-answer process.

The nature of dialogues using computer aided telephony is analysed, and then the work done by members of The Speech Project on an alternative approach using a simpler dialogue structure is described.