The time course of plausibility effects on eye movements in reading: Evidence from noun-noun compounds.

Readers' eye movements were monitored as they read sentences containing noun-noun compounds that varied in frequency (e.g., elevator mechanic, mountain lion). The left constituent of the compound was either plausible or implausible as a head noun at the point at which it appeared, whereas the compound as a whole was always plausible. When the head noun analysis of the left constituent was implausible, reading times on this word were inflated, beginning with the first fixation. This finding is consistent with previous demonstrations of very rapid effects of plausibility on eye movements. Compound frequency did not modulate the plausibility effect, and all disruption was resolved by the time readers' eyes moved to the next word. These findings suggest (contra Kennison, 2005) that the parser initially analyzes a singular noun as a head instead of a modifier. In addition, the findings confirm that the very rapid effect of plausibility on eye movements is not due to strategic factors, because in the present experiment, unlike in previous demonstrations, this effect appeared in sentences that were globally plausible. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Formation and retention of local melted films in AZ91 friction stir spot welds

The formation of local melted films during friction stir spot welding of as-cast AZ91D and thixomolded AZ91 material is investigated. The average temperatures close to the tip of the rotating pin vary from 438 to 454 °C during the dwell period in friction stir spot welding. These measured temperature values are higher than the melting temperature of α-Mg + Mg₁₇Al₁₂ eutectic (437 °C). It is suggested that the temperature in the stir zone during the dwell period is determined by the relative proportions of α-Mg and (α-Mg + Mg₁₇Al₁₂) eutectic material, which are incorporated during friction stir spot welding. Based on the stir zone temperature measurements and a detailed examination of material located at the root of the pin thread it is suggested that material is moved downwards via the pin thread and into the stir zone during the dwell period in friction stir spot welding. Evidence of local melted film formation is observed in the stir zone of AZ91 spot welds. It is suggested that melted films are retained since their dissolution rate is much slower in the high temperature stir zone than it is when melted films is formed in the stir zone during Al 7075-T6 friction stir spot welding. The spontaneous melting temperature, solute diffusion rate and the thermodynamic driving force for droplet dissolution are much higher during Al 7075-T6 friction stir spot welding.     

Gelling of alginate fibres

Equipment was developed to measure the time for complete gelling of sodium alginate fibres in calcium chloride solution, taken as the time to achieve maximum tensile strength. The effects of fibre diameter, alginate concentration, alginate composition and calcium chloride concentration on gelling time were investigated. A diffusional model, developed to predict the gelling time, agreed with experimental results except for the effect of calcium ion concentration which was modelled empirically.     

Location of Aluminum in Substituted Calcium Silicate Hydrate (C-S-H) Gels as Determined by 29Si and 27Al NMR and EELS

Solid-state ²⁷Al and ²⁹Si magic angle spinning NMR spectroscopy has been combined with electron energy loss spectroscopy carried out in the transmission electron microscope to determine the location of Al substituting in a semicrystalline C-S-H gel present in a hydrated synthetic slag glass. The gel is found to contain mainly pentameric silicate chains in which the central silicon is substituted by aluminum.     

Determination of Magnetic and Nuclear Quadrupole Interactions in La@C82 from EPR Linewidth Data

From the analysis of the temperature dependence of the EPR line width, an estimate of the anisotropic parts of the dipolar and quadrupolar hyperfine couplings of lanthanum was derived. Furthermore, the rotational correlation time of the nearly spherical molecule was found to deviate considerably from that of the solvent molecules.     

Esophagitis in Sprague-Dawley rats is mediated by free radicals

Free radical-mediated esophagitis was studied during duodenogastroesophageal reflux (mixed reflux) or acid reflux in rats. The influence of reflux on esophageal glutathione levels was also examined. Mixed reflux caused more gross mucosal injury than acid reflux. Gross mucosal injury occurred in the mid-esophagus. Total glutathione (GSH) in the esophageal mucosa of control rats was highest in the distal esophagus. The time course of esophageal GSH in rats treated by mixed reflux showed a significant decrease 4 hr after initiation of reflux, followed by a significant increase from the 12th hour on. Mucosal GSH was increased in both reflux groups after 24 hr but significantly more so in the mixed than in the acid reflux group. The free radical scavenger superoxide dismutase (SOD) prevented esophagitis and was associated with decreased GSH levels. GSH depletion by buthionine sulfoximine (BSO) prevented esophagitis and stimulated SOD production in the esophageal mucosa. It is concluded that gastroesophageal reflux is associated with oxidative stress in the esophageal mucosa. The lower GSH levels in the mid-esophagus may predispose to damage in this area. Duodenogastroesophageal reflux causes more damage than pure acid reflux. Oxidative stress leads to GSH depletion of the esophageal mucosa in the first few hours following damage but then stimulates GSH production. GSH depletion by BSO does not worsen esophagitis since it increases the esophageal SOD concentration.     

A multiagent approach to managing air traffic flow

Intelligent air traffic flow management is one of the fundamental challenges facing the Federal Aviation Administration (FAA) today. FAA estimates put weather, routing decisions and airport condition induced delays at 1,682,700 h in 2007 (FAA OPSNET Data, US Department of Transportation website, ), resulting in a staggering economic loss of over $41 billion (Joint Economic Commission Majority Staff, Your flight has been delayed again, 2008). New solutions to the flow management are needed to accommodate the threefold increase in air traffic anticipated over the next two decades. Indeed, this is a complex problem where the interactions of changing conditions (e.g., weather), conflicting priorities (e.g., different airlines), limited resources (e.g., air traffic controllers) and heavy volume (e.g., over 40,000 flights over the US airspace) demand an adaptive and robust solution. In this paper we explore a multiagent algorithm where agents use reinforcement learning (RL) to reduce congestion through local actions. Each agent is associated with a fix (a specific location in 2D space) and has one of three actions: setting separation between airplanes, ordering ground delays or performing reroutes. We simulate air traffic using FACET which is an air traffic flow simulator developed at NASA and used extensively by the FAA and industry. Our FACET simulations on both artificial and real historical data from the Chicago and New York airspaces show that agents receiving personalized rewards reduce congestion by up to 80% over agents receiving a global reward and by up to 90% over a current industry approach (Monte Carlo estimation).     

Dispersion in Disks

We present three new approximation algorithms with improved constant ratios for selecting n points in n disks such that the minimum pairwise distance among the points is maximized.

1. A very simple O(nlog?n)-time algorithm with ratio 0.511 for disjoint unit disks.
2. An LP-based algorithm with ratio 0.707 for disjoint disks of arbitrary radii that uses a linear number of variables and constraints, and runs in polynomial time.
3. A hybrid algorithm with ratio either 0.4487 or 0.4674 for (not necessarily disjoint) unit disks that uses an algorithm of Cabello in combination with either the simple O(nlog?n)-time algorithm or the LP-based algorithm.

The LP algorithm can be extended for disjoint balls of arbitrary radii in ? ^d , for any (fixed) dimension d, while preserving the features of the planar algorithm. The algorithm introduces a novel technique which combines linear programming and projections for approximating Euclidean distances. The previous best approximation ratio for dispersion in disjoint disks, even when all disks have the same radius, was 1/2. Our results give a positive answer to an open question raised by Cabello, who asked whether the ratio 1/2 could be improved.