Gauge Symmetries on θ\theta-Deformed Spaces

A Hamiltonian formulation of gauge symmetries on noncommutative ($\theta$ deformed) spaces is discussed. Both cases- star deformed gauge transformation with normal coproduct and undeformed gauge transformation with twisted coproduct- are considered. While the structure of the gauge generator is identical in either case, there is a difference in the computation of the graded Poisson brackets that yield the gauge transformations. Our analysis provides a novel interpretation of the twisted coproduct for gauge transformations.Comment: LaTex, 20 pages, no figure

The Mythology of Game Theory

Non-cooperative game theory is at its heart a theory of cognition, specifically a theory of how decisions are made. Game theory\u27s leverage is that we can design different payoffs, settings, player arrays, action possibilities, and information structures, and that these differences lead to different strategies, outcomes, and equilibria. It is well-known that, in experimental settings, people do not adopt the predicted strategies, outcomes, and equilibria. The standard response to this mismatch of prediction and observation is to add various psychological axioms to the game-theoretic framework. Regardless of the differing specific proposals and results, game theory uniformly makes certain cognitive assumptions that seem rarely to be acknowledged, much less interrogated. Indeed, it is not widely understood that game theory is essentially a cognitive theory. Here, we interrogate those cognitive assumptions. We do more than reject specific predictions from specific games. More broadly, we reject the underlying cognitive model implicitly assumed by game theory

Peak Stir Zone Temperatures during Friction Stir Processing

The stir zone (SZ) temperature cycle was measured during the friction stir processing (FSP) of NiAl bronze plates. The FSP was conducted using a tool design with a smooth concave shoulder and a 12.7-mm step-spiral pin. Temperature sensing was accomplished using sheathed thermocouples embedded in the tool path within the plates, while simultaneous optical pyrometry measurements of surface temperatures were also obtained. Peak SZ temperatures were 990 ⁰Cto 1015 ⁰C (0.90 to 0.97 TMelt) and were not affected by preheating to 400⁰C, although the dwell time above 900 ⁰C was increased by the preheating. Thermocouple data suggested little variation in peak temperature across the SZ, although thermocouples initially located on the advancing sides and at the centerlines of the tool traverses were displaced to the retreating sides, precluding direct assessment of the temperature variation across the SZ. Microstructure-based estimates of local peak SZ temperatures have been made on these and on other similarly processed materials. Altogether, the peak-temperature determinations from these different measurement techniques are in close agreement

Topics in Noncommutative Geometry Inspired Physics

In this review article we discuss some of the applications of noncommutative geometry in physics that are of recent interest, such as noncommutative many-body systems, noncommutative extension of Special Theory of Relativity kinematics, twisted gauge theories and noncommutative gravity.Comment: New references added, Published online in Foundations of Physic

Evidence of aluminum silicate formation during chemical vapor deposition of amorphous Al/sub 2/O/sub 3/ thin films Si(100)

Using narrow nuclear reaction resonance profiling, aluminum profiles are obtained in ;3.5 nm Al2O3 films deposited by low temperature ~,400 °C! chemical vapor deposition on Si~100!. Narrow nuclear resonance and Auger depth profiles show similar Al profiles for thicker ~;18 nm! films. The Al profile obtained on the thin film is consistent with a thin aluminum silicate layer, consisting of Al–O–Si bond units, between the silicon and Al2O3 layer. Transmission electron microscopy shows evidence for a two-layer structure in Si/Al2O3 /Al stacks, and x-ray photoelectron spectroscopy shows a peak in the Si 2p region near 102 eV, consistent with Al–O–Si units. The silicate layer is speculated to result from reactions between silicon and hydroxyl groups formed on the surface during oxidation of the adsorbed precursor

Evidence of aluminum silicate formation during chemical vapor deposition of amorphous Al/sub 2/O/sub 3/ thin films Si(100)

Using narrow nuclear reaction resonance profiling, aluminum profiles are obtained in ;3.5 nm Al2O3 films deposited by low temperature ~,400 °C! chemical vapor deposition on Si~100!. Narrow nuclear resonance and Auger depth profiles show similar Al profiles for thicker ~;18 nm! films. The Al profile obtained on the thin film is consistent with a thin aluminum silicate layer, consisting of Al–O–Si bond units, between the silicon and Al2O3 layer. Transmission electron microscopy shows evidence for a two-layer structure in Si/Al2O3 /Al stacks, and x-ray photoelectron spectroscopy shows a peak in the Si 2p region near 102 eV, consistent with Al–O–Si units. The silicate layer is speculated to result from reactions between silicon and hydroxyl groups formed on the surface during oxidation of the adsorbed precursor

Dressing the mind properly for the game.

Game theory as a theoretical and empirical approach to interaction has spread from economics to psychology, political science, sociology and biology. Numerous social interactions-foraging, talking, trusting, coordinating, competing-can be formally represented in a game with specific rules and strategies. These same interactions seem to rely on an interweaving of mental selves, but an effective strategy need not depend on explicit strategizing and higher mental capabilities, as less sentient creatures or even lines of software can play similar games. Human players are distinct because we are less consistent and our choices respond to elements of the setting that appear to be strategically insignificant. Recent analyses of this variable response have yielded a number of insights into the mental approach of human players: we often mentalize, but not always; we are endowed with social preferences; we distinguish among various types of opponents; we manifest different personalities; we are often guided by security concerns; and our strategic sophistication is usually modest