Evolutionary Markovian Strategies in 2 x 2 Spatial Games

Evolutionary spatial 2 x 2 games between heterogeneous agents are analyzed using different variants of cellular automata (CA). Agents play repeatedly against their nearest neighbors 2 x 2 games specified by a rescaled payoff matrix with two parameteres. Each agent is governed by a binary Markovian strategy (BMS) specified by 4 conditional probabilities [p_R, p_S, p_T, p_P] that take values 0 or 1. The initial configuration consists in a random assignment of "strategists" among the 2^4= 16 possible BMS. The system then evolves within strategy space according to the simple standard rule: each agent copies the strategy of the neighbor who got the highest payoff. Besides on the payoff matrix, the dominant strategy -and the degree of cooperation- depend on i) the type of the neighborhood (von Neumann or Moore); ii) the way the cooperation state is actualized (deterministically or stochastichally); and iii) the amount of noise measured by a parameter epsilon. However a robust winner strategy is [1,0,1,1].Comment: 18 pages, 8 figures (7 of these figures contain 4 encapsulapted poscript files each

Buyer and Seller Response to an Adverse Food Safety Event: The Case of Frozen Salmon in Alberta

Fish is a low-fat protein source high in omega-3 fatty acids, but in 2004 consumers also heard that farmed salmon had high levels of polychlorinated biphenyl (PCBs). This research evaluated how Canadian consumers and processors reacted to the conflicting health messages. Demand estimates and time-series analysis of 2001-2006 frozen meat scanner data in Alberta, Canada show a significant drop in salmon expenditure share following the PCB finding. The industry responded by launching low-priced wild salmon products, which contributed to significant demand expansion. The analysis illustrates how a food safety threat was averted and even served as a catalyst for growth.Salmon, Scanner data, Food Safety, Demand, Directed acyclic graphs, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety, D12, L15, Q11,

Market Potential for Locally Produced Meat Products

The goal of this research was to guide livestock producers in marketing, product design and pricing decisions. Tools included a focus group, a consumer taste-testing and willingness-to-pay survey, and a restaurant survey. Experience attributes of locally produced ground beef were especially competitive, and demand for credence attributes packaged under the "local" label appears consistent with a niche market that could justify verification programs. Restaurants are a potentially receptive outlet for local meats, allowing producers to avoid the barriers to entry in mainstream grocery outlets.Agribusiness,

Ionospheric and magnetospheric plasmapauses'

During August 1972, Explorer 45 orbiting near the equatorial plane with an apogee of about 5.2 R sub e traversed magnetic field lines in close proximity to those simultaneously traversed by the topside ionospheric satellite ISIS 2 near dusk in the L range 2-5.4. The locations of the Explorer 45 plasmapause crossings during this month were compared to the latitudinal decreases of the H(+) density observed on ISIS 2 near the same magnetic field lines. The equatorially determined plasmapause field lines typically passed through or poleward of the minimum of the ionospheric light ion trough, with coincident satellite passes occurring for which the L separation between the plasmapause and trough field lines was between 1 and 2. Vertical flows of the H(+) ions in the light ion trough as detected by the magnetic ion mass spectrometer on ISIS were directed upward with velocities between 1 and 2 kilometers/sec near dusk on these passes. These velocities decreased to lower values on the low latitude side of the H(+) trough but did not show any noticeable change across the field lines corresponding to the magnetospheric plasmapause

The Effects of E. Coli 0157:H7, FMD and BSE on Japanese Retail Beef Prices: A Historical Decomposition

This study examines the time-varying Japanese price reactions to the 2001 Bovine Spongiform Encephalopathy (BSE) discovery, the 2000 outbreak of foot and mouth disease (FMD), and the 1996 E. coli food po isoning events. Historical decomposition of retail-level price-series aids in explaining the behavior of beef prices in a neighborhood (period-by-period time interval) of the three events. This is based on an application of directed acyclic graphs, constructing orthogonal innovations to determine causal patterns behind contemporaneous innovations. The results show the beef safety events had different negative impacts on Japanese retail beef prices, suggesting that consumers understood and differentiated among the health risks. The results provide incentives for beef producers and retailers to proactively inform consumers about ongoing beef safety measures. Understanding consumer reaction to BSE, FMD and E. coli helps the beef industry restore consumer confidence after future food safety crises, and provides policy makers a basis for countermeasures and compensations.Japan, beef prices, BSE, FMD, E. coli, historical decomposition., Demand and Price Analysis, Food Consumption/Nutrition/Food Safety, Livestock Production/Industries, Q11, Q13,

Chains of large gaps between primes

Let $p_n$ denote the $n$-th prime, and for any $k \geq 1$ and sufficiently large $X$, define the quantity $$G_k(X) := \max_{p_{n+k} \leq X} \min( p_{n+1}-p_n, \dots, p_{n+k}-p_{n+k-1} ),$$ which measures the occurrence of chains of $k$ consecutive large gaps of primes. Recently, with Green and Konyagin, the authors showed that $$G_1(X) \gg \frac{\log X \log \log X\log\log\log\log X}{\log \log \log X}$$ for sufficiently large $X$. In this note, we combine the arguments in that paper with the Maier matrix method to show that $$G_k(X) \gg \frac{1}{k^2} \frac{\log X \log \log X\log\log\log\log X}{\log \log \log X}$$ for any fixed $k$ and sufficiently large $X$. The implied constant is effective and independent of $k$.Comment: 16 pages, no figure

Understanding the Market for Holstein Steers

A semi-structured interview process was combined with an econometric analysis to document the newly changed structure of the Holstein sector, to evaluate existing quality perceptions, and to assess the impact that recent changes in production practices have had on prices of Holstein steers. Results suggest that finished Holstein steer prices are driven by many of the same market factors as native steers, overturning some common quality misconceptions. The shift towards the calf-fed production model appears to have greatly affected the market for backgrounded Holstein steers, but had little impact on the prices for light Holstein feeder steers.Marketing,

Midlatitude Pi2 pulsations: AFGL and ISEE magnetometer observations correlated

The ISEE observations of the pi2 magnetic pulsations occuring substorm onset in the inner magnetosphere are discussed. One of these events which was also detected as a pi2 event by the AFGL midlatitude magnetometers is considered. The event occurred when the foot of the ISEE field line was over North America. The ground and satellite signals are remarkably similar: they start and stop at the same time, have the same period and can be correlated cycle by cycle. The waves are detected in the electric field data from ISEE 1 and in the magnetic field data from both ISEE 1 and ISEE 2. Calculation of the Poynting vector at ISEE 1 shows that the energy flowed mainly westward, but that there was also a component towards the nearer (southern) ionospheric foot of the field line. The phases between the various field components measured by ISEE 1 and 2 indicate that this is a standing hydromagnetic oscillation

Robust ecological pattern formation induced by demographic noise

We demonstrate that demographic noise can induce persistent spatial pattern formation and temporal oscillations in the Levin-Segel predator-prey model for plankton-herbivore population dynamics. Although the model exhibits a Turing instability in mean field theory, demographic noise greatly enlarges the region of parameter space where pattern formation occurs. To distinguish between patterns generated by fluctuations and those present at the mean field level in real ecosystems, we calculate the power spectrum in the noise-driven case and predict the presence of fat tails not present in the mean field case. These results may account for the prevalence of large-scale ecological patterns, beyond that expected from traditional non-stochastic approaches.Comment: Revised version. Supporting simulation at: http://guava.physics.uiuc.edu/~tom/Netlogo