Differential interaction nets

AbstractWe introduce interaction nets for a fragment of the differential lambda-calculus and exhibit in this framework a new symmetry between the of course and the why not modalities of linear logic, which is completely similar to the symmetry between the tensor and par connectives of linear logic. We use algebraic intuitions for introducing these nets and their reduction rules, and then we develop two correctness criteria (weak typability and acyclicity) and show that they guarantee strong normalization. Finally, we outline the correspondence between this interaction nets formalism and the resource lambda-calculus

Impact of Metals on Secondary Metabolites Production and Plant Morphology in Vetiver Grass (Chrysopogon zizanioides)

The impact of selected metals on the production of phenolic compounds was investigated in a pot trial experiment. One-month old vetiver grass (Chrysopogon zizanioides) seedlings were exposed to different concentrations (0, 10, 50, 100, and 500 ppm) of As, Cr, Cu, Fe, Ni, Pb and Zn. All the plants except for those treated with As tolerated up to 500 ppm as they did not show any signs of stress such as wilting or necrosis. A significant decrease (>35 %) in the length of the plants treated with As, compared to the control, was observed at 50 ppm which further decreased with increasing As concentration. A serious case of phytotoxicity was observed at 500 ppm As as the plant could not survive. Total soluble phenolics content in vetiver plants increased with increasing concentration of metals in the growth medium. The amount of the cell wall-bound phenolics (2.01 to 5.84 mg GAE g–1 DW) was higher than the total soluble phenolics (1.13 to 2.14 mg GAE g–1 dry weight DW) and both increased with increasing metal concentrations. Morphological changes associated with metal-induced stress were also examined with a scanning electron microscope which revealed thickened cell walls, loss of cell shape, reduction of intercellular space and the closure of stomata in leaves of metal-exposed plants.Keywords: Vetiver grass, toxic metals, phytotoxicity, phenolic compounds, morphological change

KiloHertz Bandwidth, Dual-Stage Haptic Device Lets You Touch Brownian Motion

This paper describes a haptic interface that has a uniform response over the entire human tactile frequency range. Structural mechanics makes it very difficult to implement articulated mechanical systems that can transmit high frequency signals. Here, we separated the frequency range into two frequency bands. The lower band is within the first structural mode of the corresponding haptic device while the higher one can be transmitted accurately by a fast actuator operating from conservation of momentum, that is, without reaction forces to the ground. To couple the two systems, we adopted a channel separation approach akin to that employed in the design of acoustic reproduction systems. The two channels are recombined at the tip of the device to give a uniform frequency response from DC to one kHz. In terms of mechanical design, the high-frequency transducer was embedded inside the tip of the main stage so that during operation, the human operator has only to interact with a single finger interface. In order to exemplify the type of application that would benefit from this kind of interface, we applied it to the haptic exploration with microscopic scales objects which are known to behave with very fast dynamics. The novel haptic interface was bilaterally coupled with a micromanipulation platform to demonstrate its capabilities. Operators could feel interaction forces arising from contact as well as those resulting from Brownian motion and could manoeuvre a micro bead in the absence of vision

Ion and fluid transport properties of small airways in cystic fibrosis

Rationale: Small airways constitute amajor site of pathology in cystic fibrosis (CF) and provide most of the surface area of the conducting airways of the lung. Little is known, however, about the impact of CF on ion and fluid transport in small (bronchiolar) airways. Objectives: To describe the ion and fluid transport properties of CF bronchiolar epithelium. Methods: Primary cultures of human bronchial and bronchiolar (non-CF and CF) epithelial cells were obtained. The bioelectric properties were studied in Ussing chambers and the airway surface liquid (ASL) height was measured with confocal microscopy. Main Results: Primary cultures of ΔF508 CF bronchiolar epithelial cells displayed higher transepithelial resistance than non-CF cultures, whereas baseline short circuit current and amiloride-inhibitable short circuit current were similar in both preparations. The ASL height was significantly smaller in CF compared with non-CF preparations. In the presence of amiloride, addition of forskolin increased short circuit current in non-CF but not in CF bronchiolar cultures, and the ATP-induced increase in short circuit current was lower in CF than in non-CF cultures. Non-CF bronchiolar preparations displayed larger short circuit current and fluid secretion in responses to forskolin than non-CF bronchial preparations, suggesting that CFTR-dependent Cl- transport may play a more important role in the regulation of fluid transport in small airways than in large airways. Conclusion: In CF small airways, defective Cl- secretion combined with unregulated (persistent) Na+ absorption results in ASLdepletion