On the air permeability of Populus pit

Sap hydrodynamics in vascular cells of trees seems to be controlled by small membranes called pits. Understanding how the pit junctions regulate the sap flow and stop embolism by cavitation is today a challenging issue. The hypothesis that the pit porosity adjusts the flow under negative pressure and stops the air bubble diffusion need to be validated. In this talk, we will present the experimental results on Populus trees that support the idea that pits operate "passively" in a biological point of view. This work is based on atomic force microscope (AFM) experiments, which have been realised to measure quantitatively the mechanical properties of pits at the nanoscale

Simulation evaluation of TIMER, a time-based, terminal air traffic, flow-management concept

A description of a time-based, extended terminal area ATC concept called Traffic Intelligence for the Management of Efficient Runway scheduling (TIMER) and the results of a fast-time evaluation are presented. The TIMER concept is intended to bridge the gap between today's ATC system and a future automated time-based ATC system. The TIMER concept integrates en route metering, fuel-efficient cruise and profile descents, terminal time-based sequencing and spacing together with computer-generated controller aids, to improve delivery precision for fuller use of runway capacity. Simulation results identify and show the effects and interactions of such key variables as horizon of control location, delivery time error at both the metering fix and runway threshold, aircraft separation requirements, delay discounting, wind, aircraft heading and speed errors, and knowledge of final approach speed

Evaluation of Microwave Landing System (MLS) effect on the delivery performance of a fixed-path metering and spacing system

Metering and spacing (M & S) system's algorithms described assume an aircraft two dimensional are navigation capability. The three navigation systems compared were: very high frequency omnidirectional range/distance measuring equipment (VOR/DME) and ILS, VOR/DME and + or - 40 MLS, and VOR/DME and + or - 60 MLS. Other factors studied were M & S tentative schedule point location, route geometry effects, and approach gate location effects. Summarized results are: the MLS offers some improvement over VOR/DME and ILS if all approach routes contain computer assisted turns; pilot reaction to moving the gate closer to the runway threshold may adversely affect M & S performance; and coupling en route metering to terminal scheduling transfers most of the terminal holding to more full efficient, higher altitude en route delay

Privatisation et recherche urbaine en Argentine

L'objectif de l'article est de montrer comment les difficultés de la recherche urbaine sur le terrain à Buenos Aires reflètent le décalage entre le triple discours sur la décentralisation, la modernisation et la démocratisation de l'Etat et la pratique, ainsi que les contradictions qu'implique la lente émergence de la démocratie et des pouvoirs locaux en Argentine. (Résumé d'auteur

The Spanish Dance

All through the early social history of Florida runs mention of “the Spanish Dance.” Authorities agree that, until after the war between the States, it and the waltz were far and away the favorite dances. But today, a hundred years later, is has disappeared as completely as though it never existed. It is never danced. Nothing answering its description is to be found in books on the dance, encyclopedias or histories of the dance. Two years of search and inquiry brought out not a single person who had even heard of it. “The Spanish Dance is peculiar to Florida,” Ellen Call Long wrote in Florida Breezes. 1 Here, then, was an authentic facet of Florida’s history that had passed into oblivion