Determination of Mealiness in Apples using Ultrasonic Measurements

A system based on ultrasonic energy absorbance was developed, for non-destructive measurements of three levels of texture degradation towards mealiness in Jonagold and Cox apples. The ultrasonic system comprises a high-power generator and a pair of 80 kHz ultrasonic transducers. One transducer, acting as a transmitter, sends a pulse through the apple tissue, which absorbs part of its energy, depending on internal textural attributes, and the transmitted pulse is received as an emerging signal by the other transducer. The detected ultrasound waves were analysed in parallel with the determination of the mealiness level of the fruit in accordance with destructive measurements in confined compression. The results obtained in Cox apples showed a good correlation between the ultrasound measurements and the confined-compression destructive tests for each mealiness level

The Microstructure of a U.S. Treasury ECN: The Brokertec Platform

This paper assesses the microstructure of the U.S. Treasury securities market, using newly available tick data from the BrokerTec electronic trading platform. Examining trading activity, bid-ask spreads, and depth for on-the-run two-, three-, five-, ten-, and thirty-year Treasury securities, we find that market liquidity is greater than that found in earlier studies that use data only from voice-assisted brokers. We find that the price effect of trades on BrokerTec is quite small and is even smaller once order-book information is considered. Moreover, order-book information itself is shown to affect prices. We also explore a novel feature of BrokerTec - the ability to enter hidden ('iceberg') orders - and find that, as predicted by theory, such orders are more common when price volatility is higher

Fractal Dimension Analysis of Transient Visual Evoked Potentials: Optimisation and Applications

Purpose The visual evoked potential (VEP) provides a time series signal response to an external visual stimulus at the location of the visual cortex. The major VEP signal components, peak latency and amplitude, may be affected by disease processes. Additionally, the VEP contains fine detailed and non-periodic structure, of presently unclear relevance to normal function, which may be quantified using the fractal dimension. The purpose of this study is to provide a systematic investigation of the key parameters in the measurement of the fractal dimension of VEPs, to develop an optimal analysis protocol for application. Methods VEP time series were mathematically transformed using delay time, τ, and embedding dimension, m, parameters. The fractal dimension of the transformed data was obtained from a scaling analysis based on straight line fits to the numbers of pairs of points with separation less than r versus log(r) in the transformed space. Optimal τ, m, and scaling analysis were obtained by comparing the consistency of results using different sampling frequencies. The optimised method was then piloted on samples of normal and abnormal VEPs. Results Consistent fractal dimension estimates were obtained using τ = 4 ms, designating the fractal dimension = D2 of the time series based on embedding dimension m = 7 (for 3606 Hz and 5000 Hz), m = 6 (for 1803 Hz) and m = 5 (for 1000Hz), and estimating D2 for each embedding dimension as the steepest slope of the linear scaling region in the plot of log(C(r)) vs log(r) provided the scaling region occurred within the middle third of the plot. Piloting revealed that fractal dimensions were higher from the sampled abnormal than normal achromatic VEPs in adults (p = 0.02). Variances of fractal dimension were higher from the abnormal than normal chromatic VEPs in children (p = 0.01). Conclusions A useful analysis protocol to assess the fractal dimension of transformed VEPs has been developed

Price Discovery in the Foreign Currency Futures and Spot Market

In this paper, we compare price discovery in the foreign exchange futures and spot markets during a period in which the spot market was less transparent but had higher volume than the futures market. We develop a foreign exchange futures order flow measure that is a proxy for the order flow observed by Chicago Mercantile Exchange pit traders. We find that both foreign currency futures and spot order flow contain unique information relevant to exchange rate determination. When we measure contributions to price discovery using the methods of Hasbrouck (1995) and Gonzalo and Granger (1995), we obtain results consistent with our order flow findings. Taken together, our evidence suggests that the amount of information contained in currency futures prices in 1996 is much greater than one would expect based on relative market size. Using data from 2006, we obtain quite different results, perhaps because of an increase in spot market transparency. In particular, we find in our more recent sample that the spot market has the dominant information share

Projet concerté de coopération scientifique et technique entre la France et Israël. Evaluation non destructive de la maturité de l'avocat et de la mangue par les techniques acoustique et ultrasonore

Les propriétés mécaniques, dont la fermeté, sont connues de longue date pour être de bon indicateurs de la maturité des fruits à la cueillette, de leur degré de maturation en cours de conservation ou de transport et de prédiction de leur durée de vie à l'étal. Avec la rationalisation des structures de transport et de distribution des fruits tropicaux destinés aux marchés d'exportation, le classement des fruits à la cueillette selon leur maturité s'impose de plus en plus. Il permet, entre autre, de garantir une meilleure homogénéité des lots de nature à faciliter leur gestion et leur commercialisation. Toutefois, les techniques d'évaluation des propriétés mécaniques des fruits, en relation avec leur maturité, sont dans le meilleur des cas traumatisantes (tests de déformation) et le plus souvent destructives (tests pénétrométriques). L'application de l'une de ces techniques au tri qualitatif, fruit par fruit, ne peut de ce fait être envisagée sur une chaîne automatique de conditionnement des fruits. Les techniques acoustiques et ultrasonores, couramment utilisées en contrôle non destructif des matérieux industriels non alimentaire, font de plus en plus l'objet d'études appliquées à l'estimation non destructive de la fermeté globale des fruits. Ces recherches présentent un intérêt pratique évident pour la mangue et l'avocat en raison des spécificités de ces deux espèces fruitières. La qualité des fruits proposés au consommateur dépend en effet étroitement de la maturité des fruits au moment de la cueillette et des conditions de conservation des produits. L'objectif du présent projet est d'évaluer le potentiel d'application de techniques acoustique et ultrasonore à l'évaluation non destructive de la fermeté des fruits (1) avant récolte, en vue d'optimiser la date de cueillette des fruits et (2) après récolte, afin de mieux maîtriser leur maturation et leur mise en march

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Not AvailableFTIR absorbance spectra of four foodborne pathogens suspended in four common food matrices at three different concentrations were used with artificial neural networks (ANNs) for identification and quantification. The classification accuracy of the ANNs was 93.4% for identification and 95.1% for quantification when validated using a subset of the data set. The accuracy of the ANNs when validated for identification of the pathogens studied at four different concentrations using an independent data set had an accuracy range from 60% to 100% and was strongly influenced by background noise. The pathogens could be identified irrespective of the food matrix in which they were suspended, although the classification accuracy was reduced at lower concentrations. More sophisticated background noise filtration techniques are needed to further improve the predictions.United States-Israel Binational Agricultural Research and Development Fund (Grant No. US-3296-02