Voluntary Approaches to Food Safety : A Unified Framework

The emergence and the multiplication of safety quality management system within the food supply chain were extensively analyzed in the food safety literature. Some papers deal more specifically with the voluntary implementation by firms of these systems (Segerson, 1999; Venturini, 2003; Noelke & Caswell, 2000). Our paper develops a unified analytical framework of this burgeoning literature. We show three original results: (i) when the mandatory threat is strong, the voluntary adoption of safety measures can be implemented without the need of a cost differential assumption (Segerson, 1999), or a reputation effect (Venturini, 2003); (ii) when the mandatory threat is weak, the reputation effect and the liability rule may induce the voluntary adoption only when there is a "hard" response from the consumers; (iii) when the response from consumers is "soft", a well designed contract offered by the retailer in the supply chain can induce the firm to implement voluntary safety measures. ...French Abstract : Ces dernières années en économie agro-alimentaire, la multiplication et le développement de systèmes de management de la qualité (SMQ) au sein de l'offre alimentaire ont fait l'objet un intérêt particulier. Cependant, seules quelques recherches traitent formellement de l'adoption volontaire de tels systèmes par les entreprises (Segerson, 1999; Venturini, 2003; Noelke & Caswell, 2000). Dans cet article, nous proposons un cadre analytique unifié de cette littérature émergente. Premièrement, nous relâchons les hypothèses d'existence d'un différentiel de coût entre des SMQ volontaire et réglementaire (Sergerson, 1999) ou d'un stock de réputation (Venturini, 2003). Nous montrons ainsi qu'une menace réglementaire forte est une condition nécessaire et suffisante à l'adoption volontaire par les entreprises d'un SMQ. Deuxièmement, nous distinguons deux situations lorsque la menace réglementaire est faible. D'une part, suite à une contamination sanitaire quand la réponse des consommateurs ou du marché est " forte ", les effets de réputation et le " design " de la règle de responsabilité jouent comme des incitations à l'adoption volontaire. D'autre part, quand la réponse des consommateurs (du marché) est " molle ", seul le contrat qu'offre le distributeur à l'entreprise peut induire une adoption volontaire.VOLUNTARY APPROACHES; FOOD SAFETY; SUPPLY CHAIN

DNS of Laminar to Turbulent Transition on NACA 0012 Airfoil with Sand Grain Roughness

The Lattice-Boltzmann-based solver PowerFLOW is used to perform direct numerical simulations of the transitional flow over an airfoil at Reynolds number equal to 0.657 million. The leading edge of the airfoil is covered with sand particles, represented by polyhedra, to mimic the grit used in experiments. The sensitivity of the laminar to turbulent transition to the size of these particles, grid resolution, spanwise length is evaluated and rectangular trips are also tested

Evaporation losses and dispersion of volatile organic compounds from tank farms

© 2015, Springer International Publishing Switzerland. The present study is an application of a Gaussian dispersion model to evaluate volatilization losses from tank farms. It reports methodology to estimate evaporation losses of volatile organic compounds (VOCs) from organic liquid in storage tanks. This study used fixed roof and floating roof equations for breathing and working losses. Total loss, the breathing loss, vapor pressure, molecular weight of the product, tank diameter, diurnal temperature, paint factor, tank capacity, and number of turnovers were considered and factored in the calculation. AERMOD and ALOHA softwares were used to simulate the dispersion of VOCs under normal and accidental scenarios. For the modeling purposes, meteorological data such as annual average ambient temperature, annual average atmospheric pressure, daily minimum ambient temperature, daily maximum ambient temperature, solar insulation factor, and average wind speed were included as input in the calculation and modeling activities. The study took place in Sharjah Emirate in United Arab Emirates, which borders Dubai to the south and Ajman to the north, and the three form a conurbation. The reported method was used to estimate evaporation losses for baseline and hypothetical leak scenarios. Results of this research show that liquid storage tanks in the study area emit a low concentration of VOC under the studied and assumed conditions, e.g., new tanks with high performance sealing as well as the noted earlier climatic conditions. The dispersion of those concentrations is controlled by the prevailing wind direction. The predicted VOCs concentrations were within the range of the measured VOCs values in air. The study found that the spatial distributions of the predicted concentration attenuate with time and distance. Under the reported accidental spill scenario, the Gaussian model indicates that the danger area starts within the zone of less than 10 m. The danger area is subjected to flame pockets, and the VOC concentrations in this area will exceed 19,800 ppm

Time-scales of close-in exoplanet radio emission variability

We investigate the variability of exoplanetary radio emission using stellar magnetic maps and 3D field extrapolation techniques. We use a sample of hot Jupiter hosting stars, focusing on the HD 179949, HD 189733 and tau Boo systems. Our results indicate two time-scales over which radio emission variability may occur at magnetised hot Jupiters. The first is the synodic period of the star-planet system. The origin of variability on this time-scale is the relative motion between the planet and the interplanetary plasma that is co-rotating with the host star. The second time-scale is the length of the magnetic cycle. Variability on this time-scale is caused by evolution of the stellar field. At these systems, the magnitude of planetary radio emission is anticorrelated with the angular separation between the subplanetary point and the nearest magnetic pole. For the special case of tau Boo b, whose orbital period is tidally locked to the rotation period of its host star, variability only occurs on the time-scale of the magnetic cycle. The lack of radio variability on the synodic period at tau Boo b is not predicted by previous radio emission models, which do not account for the co-rotation of the interplanetary plasma at small distances from the star.Comment: 10 pages, 7 figures, 2 tables, accepted in MNRA

Exoplanet Transit Variability: Bow Shocks and Winds Around HD 189733b

By analogy with the solar system, it is believed that stellar winds will form bow shocks around exoplanets. For hot Jupiters the bow shock will not form directly between the planet and the star, causing an asymmetric distribution of mass around the exoplanet and hence an asymmetric transit. As the planet orbits thorough varying wind conditions, the strength and geometry of its bow shock will change, thus producing transits of varying shape. We model this process using magnetic maps of HD 189733 taken one year apart, coupled with a 3D stellar wind model, to determine the local stellar wind conditions throughout the orbital path of the planet. We predict the time-varying geometry and density of the bow shock that forms around the magnetosphere of the planet and simulate transit light curves. Depending on the nature of the stellar magnetic field, and hence its wind, we find that both the transit duration and ingress time can vary when compared to optical light curves. We conclude that consecutive near-UV transit light curves may vary significantly and can therefore provide an insight into the structure and evolution of the stellar wind.Comment: 9 Pages, 7 figures. Accepted for publication in Monthly Notices of The Royal Astronomical Societ

Optimising the structure of a cascaded modular battery system for enhancing the performance of battery packs

The overall performance of battery packs may be affected by imbalances between the series connected cells which is more likely in packs with high number of cells needed to provide a high voltage as needed for example in electric vehicles. In this case, the overall capacity and power capability of the pack is limited by the weakest cell in the stack which results in incomplete utilization of the pack’s capabilities. In traditional centralized battery systems (TCBS), this is addressed by implementing cell active/passive balancing circuitry/techniques which restore some of the pack’s energy capability. This paper proposes the use of cascaded modular battery systems (CMBS) to remove the need for extra balancing circuitry and maximises the performance and reliability of a battery system containing unequal matched/aged cells. The analysis is assessing the CMBS overall system efficiency, reliability and weight compared to the TCBS for a design of a 300V/3.6kW battery system as a case study

Why Should We Care About Molecular Coevolution?

Non-independent evolution of amino acid sites has become a noticeable limitation of most methods aimed at identifying selective constraints at functionally important amino acid sites or protein regions. The need for a generalised framework to account for non-independence of amino acid sites has fuelled the design and development of new mathematical models and computational tools centred on resolving this problem. Molecular coevolution is one of the most active areas of research, with an increasing rate of new models and methods being developed everyday. Both parametric and non-parametric methods have been developed to account for correlated variability of amino acid sites. These methods have been utilised for detecting phylogenetic, functional and structural coevolution as well as to identify surfaces of amino acid sites involved in protein-protein interactions. Here we discuss and briefly describe these methods, and identify their advantages and limitations

Detection and prevalence of extended spectrum β-lactamases production among Enterobacteriaceae isolated from urinary tract infections

Urinary tract infections (UTIs) by extended-spectrum β-lactamase producing Enterobacteriaceae (ESBL-E) have become an important public health problem with a substantial economic burden, as they lead to more complicated infections, longer duration of treatment, and increases in patient mortality. A total of 1267 urine samples were collected from patients during the period of 2018 to 2020. The isolates were identified based on colony morphology and biochemical tests. Antimicrobial susceptibility testing was done by modified Kirby Bauer disc diffusion method. Resistant isolates to third generation cephalosporins were tested for ESBL production by double-disk synergy test (DDST), DDST methods on MH agar plates supplemented with cloxacillin and by confirmatory double disk test (DDT). 400 strains causing UTIs were identified and classified as members of Enterobacteriaceae. The results of antimicrobial susceptibility tests showed that 68.5% (274/400) of the Enterobacteriaceae isolates were multi-drug resistant (MDR) strains. The overall prevalence of ESBL-E was 59.5% (238/400). The highest frequencies of ESBL-E were observed in internal medicine devices (68/400) and the highest ESBL production was observed in E. coli (85/238). The ESBL producing isolates were significantly resistant to penicillins and cephalosporins compared to non-ESBL producers. However, those ESBL-E strains were sensitive to imipenem (80.2%) and nitrofurantoin (87.8%). High levels of MDR strains and ESBL-E in our study highlights the need for applying specific infection control measures, and accordingly we urge physicians to opt for specific strategies for regular surveillance of uropathogenic bacteria