A Continuation Method for Nash Equilibria in Structured Games

Structured game representations have recently attracted interest as models for multi-agent artificial intelligence scenarios, with rational behavior most commonly characterized by Nash equilibria. This paper presents efficient, exact algorithms for computing Nash equilibria in structured game representations, including both graphical games and multi-agent influence diagrams (MAIDs). The algorithms are derived from a continuation method for normal-form and extensive-form games due to Govindan and Wilson; they follow a trajectory through a space of perturbed games and their equilibria, exploiting game structure through fast computation of the Jacobian of the payoff function. They are theoretically guaranteed to find at least one equilibrium of the game, and may find more. Our approach provides the first efficient algorithm for computing exact equilibria in graphical games with arbitrary topology, and the first algorithm to exploit fine-grained structural properties of MAIDs. Experimental results are presented demonstrating the effectiveness of the algorithms and comparing them to predecessors. The running time of the graphical game algorithm is similar to, and often better than, the running time of previous approximate algorithms. The algorithm for MAIDs can effectively solve games that are much larger than those solvable by previous methods

Surprisingly Little O VI Emission Arises in the Local Bubble

This paper reports the first study of the O VI resonance line emission (1032, 1038 Angstroms) originating in the Local Bubble (or Local Hot Bubble) surrounding the solar neighborhood. In spite of the fact that O VI absorption within the Local Bubble has been observed, no resonance line emission was detected during our 230 ksec Far Ultraviolet Spectroscopic Explorer observation toward a ``shadowing'' filament in the southern Galactic hemisphere. As a result, tight 2 sigma upper limits are set on the intensities in the 1032 and 1038 Angstrom emission lines: 500 and 530 photons cm^{-2} s^{-1} sr^{-1}, respectively. These values place strict constraints on models and simulations. They suggest that the O VI-bearing plasma and the X-ray emissive plasma reside in distinct regions of the Local Bubble and are not mixed in a single plasma, whether in equilibrium with T ~ 10^6 K or highly overionized with T ~ 4 to 6 x 10^4 K. If the line of sight intersects multiple cool clouds within the Local Bubble, then the results also suggest that hot/cool transition zones differ from those in current simulations. With these intensity upper limits, we establish limits on the electron density, thermal pressure, pathlength, and cooling timescale of the O VI-bearing plasma in the Local Bubble. Furthermore, the intensity of O VI resonance line doublet photons originating in the Galactic thick disk and halo is determined (3500 to 4300 photons cm^{-2} s^{-1} sr^{-1}), and the electron density, thermal pressure, pathlength, and cooling timescale of its O VI-bearing plasma are calculated. The pressure in the Galactic halo's O VI-bearing plasma (3100 to 3800 K cm^{-3}) agrees with model predictions for the total pressure in the thick disk/lower halo. We also report the results of searches for other emission lines.Comment: accepted by ApJ, scheduled for May 2003, replacement astro-ph submission corrects typos and grammatical errors in original versio

Ecology of Thysanoptera within Cabbage Fields

The occurrence and species composition of thrips within cabbage fields were studied during 1981 and 1982. Temporal differences in abundance and species composition depended on the spatial relationship of cabbage fields to cereal and forage crops. Sticky traps within cabbage fields recorded peak flights of thrips during maturation and senescence of adjacent wheat or oat fields and cutting of adjacent alfalfa and red clover fields. These data indicate several important findings regarding the ecology of thrips in general and the possible management of Thrips tabaci Lindeman in particular. First, although there are large numbers of thrips in cabbage fields during certain time periods (e.g., maturation or harvesting of crops), most will not be T. tabaci and need not be of concern to cabbage growers. Second, there are significant differences in thrips phenology and species composition in cabbage fields, and these differences appear to be dependent on phenology and management of adjacent field and forage crops. Third, although many other species are present, T. tabaci appears to be present in adequate numbers to infest cabbage at the critical period of head formation. This critical period occurs at different times depending on area, planting date, variety, and weathe

Overwintering of the Onion Thrips, Thrips tabaci (Thysanoptera: Thripidae), in New York

A survey of overwintering thrips and the potential for Thrips tabaci Lindeman to overwinter in upstate New York were investigated during the winters of 1982-83 and 1983-84. Six species—T. tabaci, Anaphothrips obscurus (Müller), Chirothrips manicatus Haliday, Limothrips denticornis (Haliday), Frankltniella tenuicornis (Uzel), and Aptinothrips rufus (Gmelin)—were able to survive as adults in the vegetation sampled, but only Anaphothripini survived as larvae. T. tabaci adults overwinter within winter wheat, alfalfa, and weedy vegetation, and these overwintering females are capable of ovipositing on these plants during the spring. Winter wheat, oats, and alfalfa were the best oviposition and reproduction hosts we examine

Species Composition and Phenology of Thysanoptera within Field Crops Adjacent to Cabbage Fields

Studies were conducted in 1981 and 1982 to determine the general temporal occurrence of thrips in wheat, alfalfa, oat, and red clover fields adjacent to cabbage fields in upstate New York. Shifts in species composition of thrips on these crops were observed through time, and fluctuations in abundance were attributed to changes in habitat structure (e.g., maturation and senescence in wheat and oats, and cropping practices in alfalfa and red clover). All of these crops serve as a reservoir for Thrips tabaci Lindeman, which may move to and infest nearby cabbage plantings. By sampling the thrips populations within the foliage and utilizing sticky traps to monitor aerial populations, we may be able to predict the population buildup within these crops and the subsequent movement of thrips to adjacent crop

Uneven distribution of cobamide biosynthesis and dependence in bacteria predicted by comparative genomics.

The vitamin B12 family of cofactors known as cobamides are essential for a variety of microbial metabolisms. We used comparative genomics of 11,000 bacterial species to analyze the extent and distribution of cobamide production and use across bacteria. We find that 86% of bacteria in this data set have at least one of 15 cobamide-dependent enzyme families, but only 37% are predicted to synthesize cobamides de novo. The distribution of cobamide biosynthesis and use vary at the phylum level. While 57% of Actinobacteria are predicted to biosynthesize cobamides, only 0.6% of Bacteroidetes have the complete pathway, yet 96% of species in this phylum have cobamide-dependent enzymes. The form of cobamide produced by the bacteria could be predicted for 58% of cobamide-producing species, based on the presence of signature lower ligand biosynthesis and attachment genes. Our predictions also revealed that 17% of bacteria have partial biosynthetic pathways, yet have the potential to salvage cobamide precursors. Bacteria with a partial cobamide biosynthesis pathway include those in a newly defined, experimentally verified category of bacteria lacking the first step in the biosynthesis pathway. These predictions highlight the importance of cobamide and cobamide precursor salvaging as examples of nutritional dependencies in bacteria

UC-247 Wild Fire: Friend Or Foe

The U.S. Army Corp of Engineers in Carters Lake required a game that attempts to educate on the principles of both prescribed and non-prescribed fires. They request that the game be playable on an android device housed in a HOLOFIL holographic display. Additionally, it needed to be created in the mirrored format as the projection flips everything. We decided to use Unity Real-Time Development Platform to complete the game’s development. Unity is a set of tools to give content creators an all-in-one development environment that helps content creators develop games and applications. “Unity is royalty-free and does not charge on a per-title basis or require revenue sharing of your application (Unity, 2022).

Combinatorial pharmacogenomic algorithm is predictive of citalopram and escitalopram metabolism in patients with major depressive disorder

Pharmacogenomic tests used to guide clinical treatment for major depressive disorder (MDD) must be thoroughly validated. One important assessment of validity is the ability to predict medication blood levels, which reflect altered metabolism. Historically, the metabolic impact of individual genes has been evaluated; however, we now know that multiple genes are often involved in medication metabolism. Here, we evaluated the ability of individual pharmacokinetic genes (CYP2C19, CYP2D6, CYP3A4) and a combinatorial pharmacogenomic test (GeneSight Psychotropic®; weighted assessment of all three genes) to predict citalopram/escitalopram blood levels in patients with MDD. Patients from the Genomics Used to Improve DEpression Decisions (GUIDED) trial who were taking citalopram/escitalopram at screening and had available blood level data were included (N=191). In multivariate analysis of the individual genes and combinatorial pharmacogenomic test separately (adjusted for age, smoking status), the F statistic for the combinatorial pharmacogenomic test was 1.7 to 2.9-times higher than the individual genes, showing that it explained more variance in citalopram/escitalopram blood levels. In multivariate analysis of the individual genes and combinatorial pharmacogenomic test together, only the combinatorial pharmacogenomic test remained significant. Overall, this demonstrates that the combinatorial pharmacogenomic test was a superior predictor of citalopram/escitalopram blood levels compared to individual genes