Learning from History for Behavior-Based Mobile Robots in Non-Stationary Conditions

Learning in the mobile robot domain is a very challenging task, especially in non-stationary conditions. The behavior-based approach has proven to be useful in making mobile robots work in real-world situations. Since the behaviors are responsible for managing the interactions between the robots and its environment, observing their use can be exploited to model these interactions. In our approach, the robot is initially given a set of behavior-producing modules to choose from, and the algorithm provides a memory-based approach to dynamically adapt the selection of these behaviors according to the history of their use. The approach is validated using a vision- and sonar-based Pioneer I robot in non-stationary conditions, in the context of a multi-robot foraging task. Results show the effectiveness of the approach in taking advantage of any regularities experienced in the world, leading to fas t and adaptable specialization for the learning robot.     

Large Scale Integration of Functional Radio-Frequency Flexible MEMS under Large Mechanical Strain

A versatile industrial recipe of transferring nitride microelectronic components such as micro-electromechanical systems (MEMS) onto flexible and stretchable substrates is demonstrated. This method bypasses difficulties of temperature-related processing, and is applicable to large-scale and mass production. The technological process of fabrication is presented along with its underlying structural and radio-frequency characterizations. In particular, the Raman strain shifts of aluminum nitride (AlN) thin films are determined for uniaxial and biaxial mechanical deformations. The transferring process onto polymer is also demonstrated by an adhesive bonding of AlN-based MEMS onto a 200 mm silicon (Si) wafer. The devices microstructure is assessed using X-ray before and after transferring, as well as their electrical radio-frequency (RF) features when on Si and polymer substrates. Then, RF measurements are also performed on the transferred and flexible devices; some in their relaxed states, and others in an in situ manner under an increasing macroscopic strain. It is shown that bulk acoustic wave resonator MEMS are fully functional even under 12% uniaxial stretching of the substrate.     

Electrochemical oxidation of water on synthetic boron-doped diamond thin film anodes

Electrolysis in aqueous 1 M HClO₄ and 1 M H₂SO₄ solutions has been carried out under galvanostatic conditions using boron-doped diamond electrodes (BDD). Analyses of the oxidation products have shown that in 1 M HClO₄ the main reaction is oxygen evolution, while in H₂SO₄ the main reaction is the formation of H₂S₂O₈. In both electrolytes small amounts of O₃ and H₂O₂ are formed. Finally, a simplified mechanism involving hydroxyl radicals formed by water discharge has been proposed for water oxidation on boron-doped diamond anodes.     

Disease-Induced Modulation of Drug Transporters at the Blood–Brain Barrier Level

The blood–brain barrier (BBB) is a highly selective and restrictive semipermeable network of cells and blood vessel constituents. All components of the neurovascular unit give to the BBB its crucial and protective function, i.e., to regulate homeostasis in the central nervous system (CNS) by removing substances from the endothelial compartment and supplying the brain with nutrients and other endogenous compounds. Many transporters have been identified that play a role in maintaining BBB integrity and homeostasis. As such, the restrictive nature of the BBB provides an obstacle for drug delivery to the CNS. Nevertheless, according to their physicochemical or pharmacological properties, drugs may reach the CNS by passive diffusion or be subjected to putative influx and/or efflux through BBB membrane transporters, allowing or limiting their distribution to the CNS. Drug transporters functionally expressed on various compartments of the BBB involve numerous proteins from either the ATP-binding cassette (ABC) or the solute carrier (SLC) superfamilies. Pathophysiological stressors, age, and age-associated disorders may alter the expression level and functionality of transporter protein elements that modulate drug distribution and accumulation into the brain, namely, drug efficacy and toxicity. This review focuses and sheds light on the influence of inflammatory conditions and diseases such as Alzheimer’s disease, epilepsy, and stroke on the expression and functionality of the BBB drug transporters, the consequential modulation of drug distribution to the brain, and their impact on drug efficacy and toxicity.     

Chronic Inflammatory Status Observed in Patients with Type 2 Diabetes Induces Modulation of Cytochrome P450 Expression and Activity

Diabetes mellitus is a metabolic disease that causes a hyperglycemic status which leads, over time, to serious damage to the heart, blood vessels, eyes, kidneys and nerves. The most frequent form of diabetes is type 2 diabetes mellitus (T2DM) which is often part of a metabolic syndrome (hyperglycaemia, hypertension, hypercholesterolemia, abdominal obesity) that usually requires the use of several medications from different drug classes to bring each of these conditions under control. T2DM is associated with an increase in inflammatory markers such as interleukin-6 (IL-6) and the tumor necrosis factor alpha (TNF-α). Higher levels of IL-6 and TNF-α are associated with a downregulation of several drug metabolizing enzymes, especially the cytochrome P450 (P450) isoforms CYP3As and CYP2C19. A decrease in these P450 isoenzymes may lead to unexpected rise in plasma levels of substrates of these enzymes. It could also give rise to a mismatch between the genotypes determined for these enzymes, the predicted phenotypes based on these genotypes and the phenotypes observed clinically. This phenomenon is described as phenoconversion. Phenoconversion typically results from either a disease (such as T2DM) or concomitant administration of medications inducing or inhibiting (including competitive or non-competitive inhibition) a P450 isoenzyme used by other substrates for their elimination. Phenoconversion could have a significant impact on drug effects and genotypic-focused clinical outcomes. As the aging population is exposed to polypharmacy along with inflammatory comorbidities, consideration of phenoconversion related to drug metabolizing enzymes is of importance when applying pharmacogenomic results and establishing personalized and more precise drug regimens.     

Empirical Derivation of a Sequence of User Stereotypes for Language Learning

The work described here pertains to ICICLE, an intelligent tutoring system for which we have designed a user model to supply data for intelligent natural language parse disambiguation. This model attempts to capture the user's mastery of various grammatical units and thus can be used to predict the grammar rules he or she is most likely using when producing language. Because ICICLE's user modeling component must infer the user's language mastery on the basis of limited writing samples, it makes use of an inferencing mechanism that will require knowledge of stereotypic acquisition sequences in the user population. We discuss in this paper the methodology of how we have applied an empirical investigation into user performance in order to derive the sequence of stereotypes that forms the basis of our modeling component's reasoning capabilities.     

Oxidation and particle deposition modeling in plasma spraying of Ti-6Al-4V/SiC fiber composites

Plasma spraying is known to be a promising process for the manufacturing of Ti/SiC long-fiber composites. However, some improvements remain for this process to be applied in an industrial route. These include: oxygen contamination of the sprayed material through that of titanium particles before and during spraying, damage to fibers due to a high level of thermal stresses induced at the spraying stage, adequate deposition of titanium-base powder to achieve a low-porosity matrix and good impregnation of the fiber array. This article deals with work that resulted in a threefold study of the process. Oxidation was studied using electron microprobe analysis of elementary particles quenched and trapped into a closed box at various given flight distances. Oxygen diffusion phenomena within the particles are discussed from a preliminary theoretical approach coupled with experimental data. Isothermal and thermomechanical calculations were made using the ABAQUS code to determine stresses arising from contact of a liquid Ti-6Al-4V particle onto a SiC fiber. On the scale of the sprayed powder flow, a two-dimensional new type of model simulating the deposition of droplets onto a substrate was developed. This new type of model is based on a lattice-gas automaton that reproduces the hydrodynamical behavior of fluids.     

Internal stress control in epoxy resins and their composites by material and process tailoring

The development of internal stress during cure of epoxy and hyperbranched polymer-modified epoxy resins was characterized, taking into account the evolving viscoelastic properties, the volumetric shrinkage due to the chemical reaction, and the thermal expansion. A criterion for void formation during cure in a constrained mold was proposed, providing guidelines for the construction of a process window for manufacturing of void-free composites. It was shown that the internal stress development in epoxy resins during cure is strongly influenced by the presence of hyperbranched polymer modifiers. The role of these modifiers was illustrated for the case of autoclave processing of glass fiber/epoxy composites. This study showed that higher fiber volume fractions could be used with hyperbranched polymer-modified resins than with unmodified resins, for producing void-free laminates. It also appeared that by suitable tailoring of the process cycle, a fully stress-free laminate could be obtained after cure, using the modified resin.