An Abstract Interpretation framework for genotype elimination algorithms

We apply Abstract Interpretation to the problem of genotype elimination in pedigrees. First, we give a formalization of some existing algorithms that try to remove from pedigrees all genotypes that violate the Mendelian rules of inheritance. The formalization enables the application of the Abstract Interpretation technique to the problem. We then introduce a particular abstraction, parameterized on given partitions of the set of genotypes. We instantiate this abstraction in order to obtain two existing algorithms for Allele Consolidation, thus giving a formal proof of their correctness. Moreover, the second of these two algorithms is shown to be an example of a forward complete abstraction

The fluidization behaviour of ignimbrite at high temperature and with mechanical agitation

Experiments were carried out to study the fluidization behaviour of ignimbrite at high temperature and while being mechanically agitated. Geldart group C behaviour occurs up to 565 degreesC when the material is subjected to increasing gas flow ( without agitation) from the loosely packed state. In contrast, even gentle mechanical agitation inhibits channelling and results in group-A type behaviour with homogeneous (non-bubbling) expansions of up to 30 - 40%. Bed collapse tests exhibit group-C behaviour at room temperature, group-A behaviour at 200 - 565 degreesC, and transitional behaviour at 55 degreesC. Both elevated temperature and mechanical agitation greatly increase the fluidizability of ignimbrite. It is inferred that a combination of high temperature and shear during transport will promote Geldart group A behaviour in pyroclastic flows

A rheological model for the flowability of aerated fine powders

A mechanically stirred fluid-bed rheometer (msFBR) was used to study the rheology of powders aerated below the fluidisation threshold. Glass ballotini (group B) and silica powders (group A) with different fine contents were tested. The torque necessary to rotate an impeller immersed in a bed of aerated powders was measured for different impeller depths and aeration rates. A model was developed: (a) to estimate the state of stress at the impeller depth, following Janssen’s approach for the evaluation of stresses in silos, and (b) to evaluate the torque, with the hypothesis that it is determined by the powder shear on a flat cylinder surface around the impeller. The model uses some powder properties, such as the dynamic and the wall yield loci of the powder used, which were estimated with a Peschl shear cell modified for small loads. The reasonable prediction of the torque at impeller depth larger than 3 cm provided by the model supports the hypothesis that the torque is defined by the plastic deformation of powders and can be explained within a simple Mohr–Coulomb approach to powder flow. The passive stress distribution that appears to set up during the shearing experiments leaves open some fundamental questions regarding the limiting conditions determining such behaviour. As in previous experiments found in the literature, aeration does not affect the rheology of powders but modifies the stress distribution within the bed. The content of fines turns out to be a key factor in the determination of powder rheology as measured both with the shear cell and with the fluid-bed rheometer

A CFD-VOF based model to address intensive photobioreactor design

The design and optimization of photobioreactors for intensive microalgal cultures are key issues to increase process performance. A model to assess the photosynthetic performance of tubular, bubble column and flat photobioreactors is presented. The model has coupled microalgal light distribution, photosynthesis kinetics and gas-liquid hydrodynamics. A lumped kinetic parameter model of photosynthetic unit (PSU) has been adopted for photosynthetic reactions. The dynamics of a microalgal cell has been described according to the gas-liquid flow of a bubble column. The flow field induced by liquid turbulence and bubbles uprising throughout the photobioreactor have been simulated with ANSYS-FLUENT. A representative domain of the flat photobioreactor has been selected by adopting proper periodic boundary conditions. Turbulence dispersion fields have been assessed by numerical simulations for several bubble size. A random-walk model developed in MATLAB has been adopted to microalgal cells to assess the irradiance experienced by the PSU-cell in the photobioreactors. The photobioreactor performances - expressed in terms of global photosynthesis rate – have been assessed. Irradiance level and biomass concentration have been changed in the range of operating conditions typically adopted for known processes

Biological Responses to Cadmium Stress in Liverwort Conocephalum conicum (Marchantiales)

Oxidative damage (production and localization of reactive oxygen species) and related response mechanisms (activity of antioxidant enzymes), and induction of Heat Shock Protein 70 expression, have been studied in the toxi-tolerant liverwort Conocephalum conicum (Marchantiales) in response to cadmium stress using two concentrations (36 and 360 µM CdCl2). Cadmium dose-dependent production of reactive oxygen species (ROS) and related activity of antioxidant enzymes was observed. The expression level of heat shock protein (Hsp)70, instead, was higher at 36 µM CdCl2 in comparison with the value obtained after exposure to 360 µM CdCl2, suggesting a possible inhibition of the expression of this stress gene at higher cadmium exposure doses. Biological responses were related to cadmium bioaccumulation. Since C. conicum was able to respond to cadmium stress by modifying biological parameters, we discuss the data considering the possibility of using these biological changes as biomarkers of cadmium pollution