Last-touch correlated data streaming

Recent research advocates address-correlating predictors to identify cache block addresses for prefetch. Unfortunately, address-correlating predictors require correlation data storage proportional in size to a program's active memory footprint. As a result, current proposals for this class of predictor are either limited in coverage due to constrained on-chip storage requirements or limited in prediction lookaheaddue to long off-chip correlation data lookup. In this paper, we propose Last-Touch Correlated Data Streaming (LT-cords), a practical address-correlating predictor. The key idea of LT-cords is to record correlation data off chip in the order they will be used and stream them into a practicallysized on-chip table shortly before they are needed, thereby obviating the need for scalable on-chip tables and enabling low-latency lookup. We use cycle-accurate simulation of an 8-way out-of-order superscalar processor to show that: (1) LT-cords with 214KB of on-chip storage can achieve the same coverage as a last-touch predictor with unlimited storage, without sacrificing predictor lookahead, and (2) LT-cords improves performance by 60% on average and 385% at best in the benchmarks studied. © 2007 IEEE

The relationship of life stage to daily social patterns of captive African elephants (Loxodonta africana) and the correlation of handler perceptions of elephant personality to demonstrated social behaviors

Elephants typically have very strong social bonds, and social interactions can include affiliative, agonistic, or ambiguous behaviors. The social interactions and dominance hierarchy between individuals of a herd depend upon many factors, including maternal lineage, age, and sex. This study was designed to determine how social behaviors among a herd of captive African elephants varied throughout the day and to establish if the frequency of social interactions and age class were correlated. The study also aimed to determine if handler perceptions of elephant personality were an accurate predictor of the type and frequency of social behaviors observed, in addition to the factors stated above. The research was performed at the African Elephant Research Unit at Knysna Elephant Park (KEP) in South Africa. The herd included 7 elephants in 3 age groups: juvenile (0-10 years), young adult (11-20 years), and adult (20+ years). Continuous, all-occurrence sampling of pre-determined affiliative, agonistic, and ambiguous social behaviors was performed for a total of 90.4 hours within a seven-week period. Results indicated that there was a statistically higher rate of affiliative, agonistic, and total social behaviors initiated during mid-morning than during mid-afternoon, but no statistical difference in ambiguous social behaviors initiated throughout the day. Additionally, elephant handlers were individually surveyed regarding perceptions of each elephant’s personality traits, including qualities of dominance, activity level, boldness, confidence, curiosity, sociability, and aggressiveness. This characterization was compared to the previously recorded elephant social behaviors, and results indicated that there was a strong positive correlation between observed agonistic rate of social behavior and rated activity levels. Results are intended to influence the management of captive elephants at KEP and elsewhere

Experimental Signatures of Critically Balanced Turbulence in MAST

Beam Emission Spectroscopy (BES) measurements of ion-scale density fluctuations in the MAST tokamak are used to show that the turbulence correlation time, the drift time associated with ion temperature or density gradients, the particle (ion) streaming time along the magnetic field and the magnetic drift time are consistently comparable, suggesting a "critically balanced" turbulence determined by the local equilibrium. The resulting scalings of the poloidal and radial correlation lengths are derived and tested. The nonlinear time inferred from the density fluctuations is longer than the other times; its ratio to the correlation time scales as $\nu_{*i}^{-0.8\pm0.1}$, where $\nu_{*i}=$ ion collision rate/streaming rate. This is consistent with turbulent decorrelation being controlled by a zonal component, invisible to the BES, with an amplitude exceeding the drift waves' by $\sim \nu_{*i}^{-0.8}$.Comment: 6 pages, 4 figures, submitted to PR

Effects of automation on situation awareness in controlling robot teams

Declines in situation awareness (SA) often accompany automation. Some of these effects have been characterized as out-of-the-loop, complacency, and automation bias. Increasing autonomy in multi-robot control might be expected to produce similar declines in operators’ SA. In this paper we review a series of experiments in which automation is introduced in controlling robot teams. Automating path planning at a foraging task improved both target detection and localization which is closely tied to SA. Timing data, however, suggested small declines in SA for robot location and pose. Automation of image acquisition, by contrast, led to poorer localization. Findings are discussed and alternative explanations involving shifts in strategy proposed

Consequences of kinetic non-equilibrium for the nuclear equation-of-state in heavy ion collision

Highly compressed nuclear matter created in relativistic heavy collisions is to large extent governed by local non-equilibrium. As an idealized scenario colliding nuclear matter configurations are studied within both, relativistic mean field theory and using more realistic in-medium interactions based on the Dirac-Brueckner T-matrix. The equation of state in anisotropic matter is thereby governed by two competing effects: The enlarged phase space volume in colliding matter tends to soften the internal potential energy of the subsystems whereas the relative motion of the two currents leads to a strong additional repulsion in the system. An effective EOS constructed for anisotropic momentum configurations shows a significant net softening compared to ground state nuclear matter. This effect is found to be to large extend independent on the particular choice of the nuclear interaction. A critical discussion of standard transport approaches with respect to the considered non-equilibrium effects is given.Comment: 41 pages, 13 figures, to appear in Nucl. Phys.

Economic Efficiency Requires Interaction

We study the necessity of interaction between individuals for obtaining approximately efficient allocations. The role of interaction in markets has received significant attention in economic thinking, e.g. in Hayek's 1945 classic paper. We consider this problem in the framework of simultaneous communication complexity. We analyze the amount of simultaneous communication required for achieving an approximately efficient allocation. In particular, we consider two settings: combinatorial auctions with unit demand bidders (bipartite matching) and combinatorial auctions with subadditive bidders. For both settings we first show that non-interactive systems have enormous communication costs relative to interactive ones. On the other hand, we show that limited interaction enables us to find approximately efficient allocations