Ecophysiological characterization of Penicillium expansum population in lleida (Spain)

Penicillium expansum, a patulin producer fungus, is the most important fungus causing decay in cold stored both apples and pears. This can lead to patulin contaminated by-products. The aim of this assay was to evaluate the phenotypical and physiological variability in the population of P. expansum that cause fruit spoilage in post-harvest stages in Lleida (Spain). In total, 101 isolates of P. expansum from the 2004 and the 2005 seasons were obtained from decayed fruits. Significant differences were found in the observations from both seasons. Variability of the isolates in each season seemed to be partially explained by differences in growth in media, patulin accumulation and resistance to fungicides. Patulin production was detected in almost 100% of the isolates. Variability existing in P. expansum population could not be totally explained, but the above mentioned variables explained up to 74% of the diversity in some cases. The results obtained point to the existence of different populations of P. expansum in each season and may explain the differences in fungicide resistance observed between both seasons. The capacity to colonize apple flesh and some variables involved in fruit colonization were not a source of variation neither in each season nor when both seasons were compared. As storage rooms are cleaned and disinfected each season, this suggests that each season, the populations in storage rooms develop only from strains capable to colonize apple flesh. This may lead to rapid sporulation and spreading of spores.     

Impact of analytical bias in metabonomic studies of human blood serum and plasma

Concurrent with the explosion in the number of publications reporting biomarker discovery by profiling technologies, such as proteomics and pattern recognition, has been the increase in evidence highlighting the susceptibility of these approaches to analytical and experimental bias. The work presented here addresses these timely issues by delivering a detailed characterization of the effect of common sources of bias in clinical studies on serum and plasma profiles generated by a key technology in metabonomics, NMR spectroscopy. Specifically, differences in composition when blood samples were collected onto and in the absence of ice, over a series of serum-clot contact times, the stability of NMR-prepared samples over time and the effect on the metabolic profile of freeze-thawing were examined. While differences between individuals were far greater than variation from any other experimental factor, each of the conditions examined did cause slight alterations to the NMR profile that could produce a systematic bias. Variation due to clotting time caused changes in energy metabolites, which were delayed by ice with no other spectral effects. Room-temperature stability and hence NMR spectral repeatability were high (<1% intrasample variation). Higher molecular weight species such as lipoproteins were more susceptible to the variations present in the examined factors. These observations have implications for profiling study design, and hence, our results form a new and valuable resource for those attempting clinical metabolic profiling, for regulatory agencies involved in the licensing of clinical tests and in the generation of international reporting standards for metabonomics.     

Model re-parameterization and output prediction for a bioreactor system

Microalgal bioprocesses are of increasing interest due to the possibility of producing fine chemicals, pharmaceuticals, and biofuels. In this work, the parameter estimability of a first principles ODE model of a microalgal bioreactor, containing 6 states and 12 unknown parameters, is investigated. For this purpose, the system input trajectories are computed using the D-optimality criterion. Even by using a D-optimal input, not all parameters were found to have a significant effect on model predictions. Linear and non-linear transformations are used to partition the parameter space into estimable and inestimable subspaces. For the linear re-parameterization, a set of four directions in the twelve dimensional parameter space, along which a significant change in the output occurs, is identified using singular value decomposition of the parameter covariance matrix. The non-linear re-parameterization utilizes the three system rate functions as pseudo-outputs in order to perform a non-linear transformation which reduces the dimension of the parameter space from twelve to three. Both the proposed re-parameterization methods achieve a good degree of output prediction at a greatly decreased computational cost.     

Automatic voltage regulators siting in distribution systems considering hourly demand

This paper presents an approach for the best site determination of automatic voltage regulators in distribution systems taking into account hourly variations of demand. A unique objective function is defined considering losses and voltage drop indices through the weighting coefficients method and then optimized using genetic algorithms. The evaluation of the objective function is done through a Newton Raphson load flow, allowing the optimal tap position determination. To consider the variability of demand, multiple hourly deterministic optimization processes are applied considering the daily load profiles of each node. Results of the application of the proposed approach over a test system and a real distribution feeder are presented.     

Calibration approach for fluorescence lifetime determination for applications using time-gated detection and finite pulse width excitation

Time-gated techniques are useful for the rapid sampling of excited-state (fluorescence) emission decays in the time domain. Gated detectors coupled with bright, economical, nanosecond-pulsed light sources like flashlamps and nitrogen lasers are an attractive combination for bioanalytical and biomedical applications. Here we present a calibration approach for lifetime determination that is noniterative and that does not assume a negligible instrument response function (i.e., a negligible excitation pulse width) as does most current rapid lifetime determination approaches. Analogous to a transducer-based sensor, signals from fluorophores of known lifetime (0.5-12 ns) serve as calibration references. A fast avalanche photodiode and a GHz-bandwidth digital oscilloscope is used to detect transient emission from reference samples excited using a nitrogen laser. We find that the normalized time-integrated emission signal is proportional to the lifetime, which can be determined with good reproducibility (typically <100 ps) even for data with poor signal-to-noise ratios ( approximately 20). Results are in good agreement with simulations. Additionally, a new time-gating scheme for fluorescence lifetime imaging applications is proposed. In conclusion, a calibration-based approach is a valuable analysis tool for the rapid determination of lifetime in applications using time-gated detection and finite pulse width excitation.     

Spectroscopic properties of Nd 3 + and Pr 3 + in gallate glasses with low phonon energies

Absorption and fluorescence spectra of Nd3 +were measured in potassium tantalum gallate, lead bismuth gallate (PBG), fluorozirconate (ZBLAN), and Ge-Ga-S glasses. A Judd -Ofelt analysis was performed to determine the spontaneous emission probability and stimulated emission cross section of the4 F3/2 ?4 I11/2 transition of Nd3 +. Raman spectra were studied to clarify the maximum phonon energies of the glasses. The fluorescence of the1 G4?3 H5 transition of Pr3 + in a dehydrated PBG glass was observed for the first time to our knowledge. The PBG glass has a higher quantum efficiency than that of ZBLAN glass based on the Judd -Ofelt analysis.     

Continuous Cooling Transformations in Nuclear Pressure Vessel Steels

A class of low-alloy steels often referred to as SA508 represent key materials for the manufacture of nuclear reactor pressure vessels. The alloys have good properties, but the scatter in properties is of prime interest in safe design. Such scatter can arise from microstructural variations but most studies conclude that large components made from such steels are, following heat treatment, fully bainitic. In the present work, we demonstrate with the help of a variety of experimental techniques that the microstructures of three SA508 Gr.3 alloys are far from homogeneous when considered in the context of the cooling rates encountered in practice. In particular, allotriomorphic ferrite that is expected to lead to a deterioration in toughness, is found in the microstructure for realistic combinations of austenite grain size and the cooling rate combination. Parameters are established to identify the domains in which SA508 Gr.3 steels transform only into the fine bainitic microstructures.     

Development of the Multidimensional Acculturative Stress Inventory for adults of Mexican origin.

The Multidimensional Acculturative Stress Inventory (MASI), a 36-item stress measure that was developed to assess acculturative stress among persons of Mexican origin living in the United States, was tested on a community sample of 174 adults (117 women, 57 men). Principal-components analyses yielded 4 stable and internally consistent factors: Spanish Competency Pressures (7 items), English Competency Pressures (7 items), Pressure to Acculturate (7 items), and Pressure Against Acculturation (4 items). These 4 factors accounted for 64.4% of the variance and correlated in the expected directions with criterion measures of acculturation and/or psychological adjustment. Further reliability and validity testing of the MASI is discussed as well as the utility of this measure in assessing acculturative stress among adults of Mexican origin. (PsycINFO Database Record (c) 2011 APA, all rights reserved)