Resource-driven Substructural Defeasible Logic

Linear Logic and Defeasible Logic have been adopted to formalise different features relevant to agents: consumption of resources, and reasoning with exceptions. We propose a framework to combine sub-structural features, corresponding to the consumption of resources, with defeasibility aspects, and we discuss the design choices for the framework

Sum of exit times in series of metastable states in probabilistic cellular automata

Reversible Probabilistic Cellular Automata are a special class of automata whose stationary behavior is described by Gibbs--like measures. For those models the dynamics can be trapped for a very long time in states which are very different from the ones typical of stationarity. This phenomenon can be recasted in the framework of metastability theory which is typical of Statistical Mechanics. In this paper we consider a model presenting two not degenerate in energy metastable states which form a series, in the sense that, when the dynamics is started at one of them, before reaching stationarity, the system must necessarily visit the second one. We discuss a rule for combining the exit times from each of the metastable states

Metastability for reversible probabilistic cellular automata with self--interaction

The problem of metastability for a stochastic dynamics with a parallel updating rule is addressed in the Freidlin--Wentzel regime, namely, finite volume, small magnetic field, and small temperature. The model is characterized by the existence of many fixed points and cyclic pairs of the zero temperature dynamics, in which the system can be trapped in its way to the stable phase. %The characterization of the metastable behavior %of a system in the context of parallel dynamics is a very difficult task, %since all the jumps in the configuration space are allowed. Our strategy is based on recent powerful approaches, not needing a complete description of the fixed points of the dynamics, but relying on few model dependent results. We compute the exit time, in the sense of logarithmic equivalence, and characterize the critical droplet that is necessarily visited by the system during its excursion from the metastable to the stable state. We need to supply two model dependent inputs: (1) the communication energy, that is the minimal energy barrier that the system must overcome to reach the stable state starting from the metastable one; (2) a recurrence property stating that for any configuration different from the metastable state there exists a path, starting from such a configuration and reaching a lower energy state, such that its maximal energy is lower than the communication energy

Research Notes : The monogenic and digenic control of hypocotyl and flower color in soybeans

The pigmentation of seedling hypocotyl is important in the knowledge, at a very early stage, of success in the cross of plants differing in this aspect. Several genes, among which are W1, W2, W3, W4 and wm, have been recognized as controlling flower pigmentation, and many studies indicate that flower and hypocotyl colors are closely associated. Hartwig and Hinson (1962) put in evidence that hypocotyl of W1W3W4 genotypes is darker than that of W1w3W4 ones

Estimates of the effect on hepatic iron of oral deferiprone compared with subcutaneous desferrioxamine for treatment of iron overload in thalassemia major: a systematic review

BACKGROUND: Beta thalassemia major requires regular blood transfusions and iron chelation to alleviate the harmful accumulation of iron. Evidence on the efficacy and safety of the available agents, desferrioxamine and deferiprone, is derived from small, non-comparative, heterogeneous observational studies. This evidence was reviewed to quantitatively compare the ability of these chelators to reduce hepatic iron. METHODS: The literature was searched using Medline and all reports addressing the effect of either chelator on hepatic iron were considered. Data were abstracted independently by two investigators. Analyses were performed using reported individual patient data. Hepatic iron concentrations at study end and changes over time were compared using ANCOVA, controlling for initial iron load. Differences in the proportions of patients improving were tested using χ(2). RESULTS: Eight of 11 reports identified provided patient-level data relating to 30 desferrioxamine- and 68 deferiprone-treated patients. Desferrioxamine was more likely than optimal dose deferiprone to decrease hepatic iron over the average follow-up of 45 months (odds ratio, 19.0, 95% CI, 2.4 to 151.4). The degree of improvement was also larger with desferrioxamine. CONCLUSIONS: This analysis suggests that desferrioxamine is more effective than deferiprone in lowering hepatic iron. This comparative analysis – despite its limitations – should prove beneficial to physicians faced with the challenge of selecting the optimal treatment for their patients

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

Variable Annuities: Risk Identification and Risk Assessment

Life annuities and pension products usually involve a number of ‘guarantees’, such as, e.g., minimum accumulation rates, minimum annual payments and minimum total payout. Packaging different types of guarantees is the feature of the so-called Variable Annuities. Basically, these products are unit-linked investment policies providing deferred annuity benefits. The guarantees, commonly referred to as GMxBs (namely, Guaranteed Minimum Benefits of type ‘x’), include minimum benefits both in case of death and survival. Following a Risk Management-oriented approach, this paper first aims at singling out all sources of risk affecting Variable Annuities (‘risk identification phase’). Critical aspects arise from the interaction between financial and demographic issues. In particular, the longevity risk may have a dramatic impact on the technical equilibrium of a portfolio. Then, we deal with risk quantification (‘risk assessment phase’), mostly via stochastic simulation of financial and demographic scenarios. Our main contribution is to present an integrated approach to risks in Variable Annuity products, so providing a unifying and innovative point of view

ASSESSMENT OF KINETICS FOR BUTANOL PRODUCTION BY CLOSTRIDIUM ACETOBUTYLICUM

The economic scenario established at the beginning of the third millennium has revived the interest in Acetone-Butanol-Ethanol (ABE) fermentations. Recent developments in molecular techniques applied to solventogenic microrganisms in combination with recent advances in fermentation systems and downstream processing have contributed to improve ABE fermentation processes feasibility and competitiveness. The challenges raised over the last years as regards ABE production may be synthesized in: i) use of renewable resources as substrate; ii) selection of strains characterized by high ABE productivity; iii) development of new fermentation systems; iv) development of new downstream strategies for enhanced solvent recovery. The selection of unconventional substrates is favoured by the ability of clostridia strains to metabolize a wide range of carbohydrates like glucose, lactose, etc...., typically present in wastewater streams e.g. from food industries. Even though clostridia have been proven successful to produce ABE, information about kinetics of substrate conversion, cell growth and butanol production is still lacking. Studies available in literature most typically regard batch tests whose results do not apply easily to continuous processes. The strong interaction between the growth/acidogenesis phase and the solventogenesis phase should be taken into account. The reactor systems investigated for the ABE fermentation belong to the batch and fed-batch typologies. Some attempts are reported in literature regarding continuous fermentation by means of clostridia strains confined in the reactor by immobilization or cell-recycling. The present study reports the preliminary results of a research activity aiming at investigating the feasibility of the ABE production by Clostridium acetobutylicum ATCC824 in a continuous biofilm reactor adopting cheese whey as feedstock. The contribution regards the characterization of the kinetics related to the ABE production process by free C. acetobutylicum ATCC824 adopting as medium lactose solutions, in order to emulate the cheese whey. The conversion process is characterized in terms of cells, acids, solvents, pH, gas composition and total organic compounds as a function of time. Results are worked out to assess the kinetics of the cells growth and of the ABE production. The yields of the carbon source in cells, acids and solvents are also assessed. The investigation is carried out adopting both batch reactors and two continuous reactors. In particular, the continuous reactors are equipped to operate under controlled conversion regimes, acidogenesis or solventogenesis. Tests carried out under batch conditions show that: i) cells growth follows the Monod kinetics for lactose concentration (CL) smaller than 100 g/L; ii) the butanol specific production rate increases linearly with CL; iii) the lactose conversion - measured at the end of the solventogenesis phase - decreases with CL; iv) the selectivity of butanol with respect to total solvents increases with CL and stabilizes at about 72%W for CL larger than 30 g/L. Preliminary tests carried out with the continuous reactor operated under solventogenesis regime show that steady state establishes with respect to cells and metabolites concentration at dilution rate of about 0.04 h-1

Assessment and monitoring of ventilatory function and cough efficacy in patients with amyotrophic lateral sclerosis.

Assessing and monitoring respiratory muscle function is crucial in patients with Amyotrophic Lateral Sclerosis, since impaired function can lead to either ventilatory failure or respiratory tract infection. Spirometry, diffusing capacity of the lung, breathing pattern, sleep study, blood gas analysis and respiratory muscle strength tests, as well as cough peak flow and cough expiratory volume measurements can provide relevant information on ventilatory function and cough efficacy. With regard to respiratory muscle strength testing, the rational approach consists in starting with volitional and non-invasive tests and later using invasive and non-volitional tests. This review focuses on both ventilatory and respiratory muscle strength testing, in order to undertake a timely treatment of respiratory failure and/or impaired cough efficacy. So far, the current literature has not highlighted any gold standard which stipulates when to commence ventilation and cough support in patients with Amyotrophic Lateral Sclerosis. A composite set of clinical and functional parameters is required for treatment scheduling to monitor lung involvement and follow-up in these patients

Abrupt Convergence and Escape Behavior for Birth and Death Chains

We link two phenomena concerning the asymptotical behavior of stochastic processes: (i) abrupt convergence or cut-off phenomenon, and (ii) the escape behavior usually associated to exit from metastability. The former is characterized by convergence at asymptotically deterministic times, while the convergence times for the latter are exponentially distributed. We compare and study both phenomena for discrete-time birth-and-death chains on Z with drift towards zero. In particular, this includes energy-driven evolutions with energy functions in the form of a single well. Under suitable drift hypotheses, we show that there is both an abrupt convergence towards zero and escape behavior in the other direction. Furthermore, as the evolutions are reversible, the law of the final escape trajectory coincides with the time reverse of the law of cut-off paths. Thus, for evolutions defined by one-dimensional energy wells with sufficiently steep walls, cut-off and escape behavior are related by time inversion.Comment: 2 figure