A supervised data-driven approach for microarray spot quality classification

In this paper, the problem of classifying the quality of microarray data spots is addressed, using concepts derived from the supervised learning theory. The proposed method, after extracting spots from the microarray image, computes several features, which take into account shape, color and variability. The features are classified using support vector machines, a recent statistical classification technique that is being employed widely. The proposed method does not make any assumptions on the problem and does not require any a priori information. The proposed system has been tested in a real case, for several different parameters’ configurations. Experimental results show the effectiveness of the proposed approach, also in comparison with state-of-the-art methods.     

Uptake of Escherichia coli, Vibrio cholerae non-O1 and Enterococcus durans by, and depuration of mussels (Mytilus galloprovincialis)

The uptakes of Escherichia coli, Vibrio cholerae non-O1 and Enterococcus durans by mussels (Mytilus galloprovincialis) and the times for depuration were investigated in order to determine the most useful indicator of vibrio contamination. The mussels were maintained in tanks of static seawater contaminated with bacteria at 5 log10 CFU/ml for bioaccumulation. Depuration was carried out by circulating fresh seawater through the tanks. Each organism was presented alone and with others to mussels, at temperatures of 14 and 21 degrees C. In water contaminated with either single or mixed organisms, the bacteria accumulated rapidly in the mussels reaching high concentrations after 1 h. With both single and mixed organisms, the maximum numbers of E. coli in mussels were 6.6 log10 CFU/g at 14 degrees C and 5.4 log10 CFU/g at 21 degrees C. Both V. cholerae non-O1 and E. durans alone or with other organisms reached a number ranging from 6.5 to 7 log10 CFU/g at both temperatures. During depuration the numbers of all the organisms slowly decreased, with E. coli alone, numbers ranged from 2.8 to 2 log10 CFU/g after 72 h at both 14 and 21 degrees C, and the organisms were undetectable after 144 h. With mixed organisms at 14 degrees C E. coli became undetectable after 168 h but at 21 degrees C no E. coli were recovered after 72 h. At 14 degrees C V. cholerae non-O1 alone also was undetectable after 168 h, but at 21 degrees C and with mixed organisms at both temperatures. V. cholerae was recovered after 168 h at numbers about 1 log10 CFU/g. After 168 h numbers of E. durans alone ranged from 2.6 log10 CFU/g at 14 degrees C to 1.5 log10 CFU/g at 21 degrees C, and with mixed organisms the numbers ranged from 2.3 to 2.0 log10 CFU/g at both temperatures. Of the three bacteria of faecal origin, E. durans is quickly acquired by mussels and released more slowly than the others, while E. coli quickly becomes undetectable. The results suggest that, for this kind of seafood, enterococci may be a more appropriate indicator than E. coli of risks to consumers from vibrios.     

Correlates of maximal oxygen consumption during treadmill exercise

According to the Balke treadmill protocol, 39 healthy male USAF volunteers were subjected to maximal exercise. The subjects as a group passed the anaerobic threshold by the end of exercise since average venous lactate concentrations increased from 11.2 +/- 1.6 mg% (95% confidence limits) to 93.0 +/- 8.5 mg% (95% confidence limits), and the average gas exchange ratio (R) at the end of the exercise was greater than unity (p less than 0.0005). Tests for correlations showed weak but statistically significant (p less than 0.05) relationships between change in venous lactic acid concentrations and R (r = 0.44) and maximal heart rate (r = 0.34). Maximal oxygen consumption was correlated with time of exercise (r = 0.70) and subject weight (r = 0.33). Subject age and initial plasma lactate concentrations were not significantly correlated with any other variables. Multiple linear regression yielded an equation for prediction of maximal oxygen consumption which included terms for time of exercise and subject weight. Although the multiple correlation coefficent (r = 0.75) was statistically significant (p less than 0.05), it was considered insufficient for accurate prediction of maximal oxygen consumption.     

Use of the dielectrometer for the determination of the complex dielectric constant in the microwave region in organic high polymers at various temperatures

A commercial type dielectrometer has been utilized for determining the complex dielectric constant of insulating materials as a function of temperature. For low-temperature measurements, modifications of the apparatus have been made, by which the lower section of the guide, containing the specimen, is insulated from the upper section by means of a Teflon disk, in order to permit measurements under vacuum without difficulties arising from moisture condensation. Taking into account the modifications made, relations between the experimentally measured quantities and the complex dielectric constant have been elaborated, and error analysis made, and best conditions to perform experimental measurements determined. For high- and medium-loss materials, in the low-temperature range, an accuracy of the order of 1% in ?′ and of 10% in ?″ have been calculated. Better results can be obtained for measurements at high temperature. The apparatus performance and the accuracy of measurements have been checked through measurements of the complex dielectric constant of different polar polymers at frequencies of the order of 9 × 10⁹ Hz, at temperatures between ?150 and 200°C. The experimental results are in good agreement with literature data derived from experimental measurements with other techniques and with the behavior expected on the basis of the results from radiofrequency measurements through considerations of molecular mobility in relation to molecular structure.     

Photocatalytic Selective Oxidation of 4‐Methoxybenzyl Alcohol to Aldehyde in Aqueous Suspension of Home‐Prepared Titanium Dioxide Catalyst

The photocatalytic oxidation of 4‐methoxybenzyl alcohol to p‐anisaldehyde (PAA) was performed in water with organic‐free suspensions of home‐prepared and commercial titanium dioxide (TiO₂) catalysts. The nanostructured TiO₂ samples were synthesised by boiling aqueous solutions of titanium tetrachloride (TiCl₄), under mild conditions, for different times. The crystallinity increased with the boiling time. The 4‐methoxybenzyl alcohol oxidation rate followed the same pattern but the highest yield (41.5 % mol) to PAA was found for the least crystalline sample, that showed a quantum efficiency of 0.116 %. A comparison with two commercial TiO₂ samples showed that all the home‐prepared catalysts exhibited a PAA yield higher than that of commercial ones. The only by‐products present were traces of 4‐methoxybenzoic acid and aliphatic products, carbon dioxide being the other main oxidation product.     

Extraction of a Simplified Model for Street Corner Loss in Microcells from Ray-Tracing Simulation

Microcellular propagation follows different laws than the well-known traditional models, and it is strongly affected by the street and building layout. A well-known and evident phenomenon is the street-corner effect, which consists of a sudden decrease of received field strength as soon as a mobile turns into a side street. Predictions based on ray optics, which can be applied to this case, are accurate but time-consuming. Hence, they cannot be used extensively, e.g., to plan a microcellular network in a city. In many cases, a simplified model would be suitable to give account of field strength behaviour in the transition region between line-of-sight (LOS) and non-line-of-sight (NLOS) propagation, and could be used as a basis of a complete microcellular field prediction tool. Following this approach, we propose a simple parametrical model for propagation around a corner: the parameter values have been tuned to fit the considered environment. The tuning process can be accomplished by means of either measurements or simulations. In order for the model to be as general as possible, it needs a large amount of reference data: for this reason, we used simulations performed with a validated ray-tracing software tool in a variety of situations. These simulations allow one to derive values of the various parameters as functions of the local topology (e.g., street width, distance from the street corner, etc.). The model thus tuned is compared with measurements, showing a good agreement between estimated and measured path loss. This model is shown to behave satisfactorily when compared with measurements, and it is suitable to characterise the street-corner effect in a variety of cases. Finally, this model, along with a simple model for LOS propagation (double slope, with a breakpoint caused by reflections on the ground and on building walls), is aimed at building a complete, modular prediction tool for the microcellular environment.