Microwave-Induced Combustion Synthesis of Luminescent Aluminate Powders

ISBN 978-953-51-0371-4 Chapitre

MuSCA: A multi-scale source-sink carbon allocation model to explore carbon allocation in plants. An application to static apple tree structures

Background and aims: Carbon allocation in plants is usually represented at a topological scale, specific to each model. This makes the results obtained with different models, and the impact of their scales of representation, difficult to compare. In this study, we developed a multi-scale carbon allocation model (MuSCA) that allows the use of different, user-defined, topological scales of a plant, and assessment of the impact of each spatial scale on simulated results and computation time. Methods: Model multi-scale consistency and behaviour were tested on three realistic apple tree structures. Carbon allocation was computed at five scales, spanning from the metamer (the finest scale, used as a reference) up to first-order branches, and for different values of a sap friction coefficient. Fruit dry mass increments were compared across spatial scales and with field data. Key Results: The model was able to represent effects of competition for carbon assimilates on fruit growth. Intermediate friction parameter values provided results that best fitted field data. Fruit growth simulated at the metamer scale differed of ~1 % in respect to results obtained at growth unit scale and up to 60 % in respect to first order branch and fruiting unit scales. Generally, the coarser the spatial scale the more predicted fruit growth diverged from the reference. Coherence in fruit growth across scales was also differentially impacted, depending on the tree structure considered. Decreasing the topological resolution reduced computation time by up to four orders of magnitude. Conclusions: MuSCA revealed that the topological scale has a major influence on the simulation of carbon allocation. This suggests that the scale should be a factor that is carefully evaluated when using a carbon allocation model, or when comparing results produced by different models. Finally, with MuSCA, trade-off between computation time and prediction accuracy can be evaluated by changing topological scales

Pregnancy in a Woman with Williams-Campbell Syndrome: A Case Report

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Use of the time constant related parameter fmax to calculate the activation energy of bulk conduction in ferroelectrics

The activation energy associated with bulk electrical conduction in functional materials is an important quantity which is often determined by impedance spectroscopy using an Arrhenius-type equation. This is achieved by linear fitting of bulk conductivity obtained from complex (Z*) impedance plots versus T-1 which gives an activation energy Ea(σ) or by linear fitting of the characteristic frequency fmax obtained from the large Debye peak in M’’-logf spectroscopic plots against T-1 which gives an activation energy Ea(fmax). We report an analysis of Ea(σ) and Ea(fmax) values for some typical non-ferroelectric and ferroelectric materials and employ numerical simulations to investigate combinations of different conductivity-temperature and permittivity-temperature profiles on the logfmax – T-1 relationship and Ea(fmax). Results show the logfmax – T-1 relationship and Ea(fmax) are strongly dependent on the permittivity-temperature profile and the temperature range measured relative to Tm (temperature of the permittivity maximum). Ferroelectric materials with a sharp permittivity peak can result in non-linear logfmax – T-1 plots in the vicinity of Tm. In cases where data are obtained either well above or below Tm, linear logfmax – T-1 plots can be obtained but overestimate or underestimate the activation energy for conduction, respectively. It is therefore not recommended to use Ea(fmax) to obtain the activation energy for bulk conduction in ferroelectric materials, instead Ea(σ) should be used

Exploring carbon allocation with a multi-scale model: the case of apple

UMR AGAP - équipe AFEF - Architecture et fonctionnement des espèces fruitièresUnderstanding the allocation of carbohydrates among organs is necessary to predict plant growth in relation to climatic conditions and agronomic practices. Despite the large number of studies on the subject of carbon allocation, no clear consensus exists on (i) the most appropriate topological scale (organ, metamer, compartment...) to represent this process on complex plant structures, and (ii) the importance of distances between organs in carbon transport. In this study, we implemented a generic source-sink based carbon allocation model, following the equation of the SIMWAL model, that takes into account the distances between sources and sinks, the sink strength and the availability of carbohydrates from photosynthesis. Our model makes use of multi-scale tree graph (MTG) to represent geometry and topology of a tree structure at different scales. Starting from the description of a plant at a given scale (e.g. metamer and growing unit scales), we defined additional grouping criteria (fruiting branches and main axis) that were used to represent the plant structure, and the process of carbon allocation at different spatial resolutions. Generic functions to determine the biomass and carbon demand of the individual organs described in an MTG were implemented and calibrated for apple trees (Fuji variety) by means of age and organ type dependent allometric equations and maximum potential Relative Growth Rate curves (RGR) obtained in a field experiment. Photosynthesis for individual leaves of the input MTG was estimated by means of a radiative model (RATP). The model was then applied to architectural mock-ups in the MTG format produced by the MappleT model, representing trees with high and low fruit loads. Simulations on simplified plant structures qualitatively showed the influence of the scale of representation and of the distance parameter on the predicted carbon allocation. In order to test assumptions regarding the effect of distance, the source-sink behavior and the suitability of the alternative scales of representation for predicting carbon allocation, the variability and spatial distribution of the simulated RGR were compared to field observations. Finally, a benchmarking was performed to compare the computational efficiency of the model when running at different scales. The presented multiscale model provides a framework to re-interpret the plant topology in order to test the influence of some assumptions at the basis of the carbon allocation process, such as branch autonomy or the effect of distance. It is also a mean to investigate the trade-offs between the detail at which a plant is described, and the accuracy and computational efficiency in predicting carbon allocation. The present work was developed on the OpenAlea platform, and will provide existing Functional Structural Plant Models with a new generic model to simulate carbon allocation in plants

Nationwide survey on the management of pediatric pharyngitis in Italian emergency units

Background: Acute pharyngitis is a frequent reason for primary care or emergency unit visits in children. Most available data on pharyngitis management come from primary care studies that demonstrate an underuse of microbiological tests, a tendency to over-prescribe antibiotics and a risk of antimicrobial resistance increase. However, a comprehensive understanding of acute pharyngitis management in emergency units is lacking. This study aimed to investigate the frequency of rapid antigen test use to diagnose acute pharyngitis, as well as other diagnostic approaches, the therapeutic attitude, and follow-up of children with this condition in the emergency units. Methods: A multicentric national study was conducted in Italian emergency departments between April and June 2022. Results: A total of 107 out of 131 invited units (response rate 82%), participated in the survey. The results showed that half of the units use a scoring system to diagnose pharyngitis, with the McIsaac score being the most commonly used. Most emergency units (56%) were not provided with a rapid antigen diagnostic test by their hospital, but the test was more frequently available in units visiting more than 10,000 children yearly (57% vs 33%, respectively, p = 0.02). Almost half (47%) of the units prescribe antibiotics in children with pharyngitis despite the lack of microbiologically confirmed cases of Group A β-hemolytic streptococcus. Finally, about 25% of units prescribe amoxicillin-clavulanic acid to treat Group A β-hemolytic streptococcus pharyngitis. Conclusions: The study sheds light on the approach to pharyngitis in emergency units, providing valuable information to improve the appropriate management of acute pharyngitis in this setting. The routinary provision of rapid antigen tests in the hospitals could enhance the diagnostic and therapeutic approach to pharyngitis