Statistical mechanics of voting

Decision procedures aggregating the preferences of multiple agents can produce cycles and hence outcomes which have been described heuristically as `chaotic'. We make this description precise by constructing an explicit dynamical system from the agents' preferences and a voting rule. The dynamics form a one dimensional statistical mechanics model; this suggests the use of the topological entropy to quantify the complexity of the system. We formulate natural political/social questions about the expected complexity of a voting rule and degree of cohesion/diversity among agents in terms of random matrix models---ensembles of statistical mechanics models---and compute quantitative answers in some representative cases.Comment: 9 pages, plain TeX, 2 PostScript figures included with epsf.tex (ignore the under/overfull \vbox error messages

Densities of tailed frog tadpoles in small streams following watershed disturbance

Streams near Mt. St. Helens, Washington, differ in degree of watershed disturbance caused by the 1980 eruption. Summer densities of tailed frog tadpoles (Ascaphus truei) varied considerably both within and between several of these streams. Differences in density among streams were most clearly associated with differences in extent of forest in the basin. Streams in basins with little forest had maximum temperatures near 20°C and few Ascaphus. In completely or partially forested basins, maximum stream temperatures were \u3c18°C, and tadpole densities were relatively high. Variation in density within streams was associated with substrate size, substrate embeddedness, and current speed. In many watersheds near Mt. St. Helens, Ascaphus is apparently locally extinct or nearly so. Reestablishment of populations in these watersheds may require several decades because of (1) the time required for habitat recovery and (2) the poor dispersal abilities of adults

Early Measurement of 200 GeV PP Large Angle Elastic Scattering

The proton-proton angular distribution would be determined in the region 4<-t<20 Gev{sup 2} at 200 Gev/c and 10<-t<20 Gev{sup 2} at 400 Gev/c by measuring both scattered protons after magnetic analysis with proportional wire chambers in Proton West. Cross sections as low as {approx}0{sup -38} cm{sup 2} /Gev{sup 2} could be measured with an average beam intensity {approx} 10{double_prime} protons/sec

Why is the rate of single parenthood lower in Canada than in the U.S.? A dynamic equilibrium analysis of welfare policies

A critical question in the design of welfare policies is whether totarget aid according to household composition, as was done in the U.S. under the Aid to Families with Dependent Children (AFDC)\ program, or to rely exclusively on means-testing, as in Canada. Restricting aid to single mothers, for instance, has the potential to distort behavior along three demographic margins: marriage, fertility and divorce. We contrast the Canadian and the U.S. policies within an equilibrium model of household formation and human capital investment on children. Policy differences weconsider are: eligibility, dependence of transfers on the number of children, and generosity of transfers. Our simulations indicate that the policy differences can account for the higher rate of single-parenthood in the U.S. They also show that Canadian welfare policy is more effective for fostering human capital accumulation among children from poor families. Interestingly, a majority of agents in our benchmark economy prefers awelfare system that targets single mothers (as the U.S. system does), yet does not (unlike the U.S. system) make transfers dependent on the number of children

Can Market Power Influence Employment, Wage Inequality and Growth?

We introduce an efficiency wage mechanism into an innovation-driven growth model. Due to asymmetric information problems the labour market is segmented and homogeneous workers may be employed either in the non-competitive intermediate sector or in the competitive research sector. We analyse the impact that the monopoly position enjoyed by intermediate firms in the product market may have on employment, wage inequality and growth, and the sectoral distribution of workers. We find that the lower the product market competition in the capital goods sector, the higher the research employment, the lower the intermediate sector employment and the higher the growth rate. The relationships between growth and inequality, on the one hand, and between growth and employment, on the other, are both negative

Sorotipos de Streptococcus suis identificados em suínos com meningite no estado do Paraná

A total of 76 samples of Streptococcus suis isolated from meningitis cases in pigs from 2005 to 2009 were evaluated. The samples were collected from 3 to 21-week-old pigs raised in 30 farms located in Paraná state, Brazil. The samples of S. suis were obtained as part of routine procedures and were serotyped by coagglutination test using rabbit hyperimmune sera for the serotypes 1 to 9 and ½. S. suis type 2 was the most frequent, followed by serotypes 1, ½ and 3