Almost Global Stochastic Stability

We develop a method to prove almost global stability of stochastic differential equations in the sense that almost every initial point (with respect to the Lebesgue measure) is asymptotically attracted to the origin with unit probability. The method can be viewed as a dual to Lyapunov's second method for stochastic differential equations and extends the deterministic result in [A. Rantzer, Syst. Contr. Lett., 42 (2001), pp. 161--168]. The result can also be used in certain cases to find stabilizing controllers for stochastic nonlinear systems using convex optimization. The main technical tool is the theory of stochastic flows of diffeomorphisms.Comment: Submitte

Sport and Crime

The publisher granted Brunel University London a permission to archive this article in BURA.Sport and crime possess the power to stir emotion and arouse debate; most people have opinions on both. Many believe a relationship exists between the two but as Francis and Braggins contend, the relationship between sport and crime is complex. For some, sport is a bastion of physical prowess and moral virtue; abiding by the rules and playing fair is considered a vehicle to encourage the wayward to veer from potential deviance or to rehabilitate offenders. A surfeit of programs designed to use sport as a method of crime control currently exist. However, sport itself contains many paradoxes and in some cases has become a realm for criminal behavior: corruption, bribery, doping, discrimination, violence, hooliganism, and a host of other undesirable behaviors are all evidenced in the delivery and practice of sport. Thus, the Hydra-headed character of sport makes the correlate between sport and crime a sometimes controversial milieu

Atrazine Degradation, Sorption and Bioconcentration in Water Systems

The herbicide atrazine is used extensively to control broadleaf and grass weeds in such crops as sorghum and corn. A small portion of the atrazine may be lost from the area of application by surface runoff and could enter a stream or lake. The objective of this study was to evaluate atrazine degradation, sorption, and bioconcentration in watersediment systems. The results indicated that sediments with lower pH values and higher organic matter levels adsorbed higher levels of atrazine than sediments with neutral pH values and lower organic matter levels. Microbial decomposition of the herbicide was slow under the conditions of this study. Accumulation of atrazine by microorganisms in an aqueous system was demonstrated4 The results indicated that the organic fraction of a water system may be the most important adsorption ccmponent. Data from this study will be useful in assessing the ramifications of herbicides in aquatic ecosystems and provide a better understanding of the reactions of herbicides in sediment-water systans

Understanding 401(k) plans

Questions about the future of the Social Security system continue to surface. As a result, interest in employer-sponsored retirement plans and other retirement investment options increases. But the restrictions and rules associated with various defined benefit plans such as 401(k), 403 (b), and 457 plans can be confusing, and these plans have risks of their own. The authors explore these plans and explain the need to view retirement savings as only one part of a portfolio.

Evaluating Labour Adjustment Costs from Trade Shocks: Illustrations for the U.S. Economy Using an Applied General Equilibrium Model With Transactions

This paper presents a general equilibrium approach to calculating labour adjustment costs induced by trade policy changes or external sector shocks, which we illustrate by analyzing the adjustment consequences of eliminating quotas and tariffs on U.S. imports. In our approach, factor adjustments in the presence of transactions costs are endogenously determined within the equilibrium structure. The conventional way of calculating such labour adjustment costs is to use full equilibrium models which exclude adjustment costs, and apply exogenous estimates of duration of unemployment to implied intersectoral labour reallocations. By using an equilibrium model in which adjustment costs are absent, the conventional approach tends to overstate the amount of labour that moves to other sectors and hence introduces an upward bias to estimates of adjustment costs. As well, such an approach tends to ignore the impact on intersectoral wage rates. Our results suggest that concerns over adjustment problems should focus as much on the consequences of adjustment costs in impeding factor mobility, as on the magnitude of the adjustment costs themselves. Compared to the redistributive effects they induce by inhibiting labour movement in response to policy or other changes, these costs may be small.

Collective non-thermal emission from an extragalactic jet interacting with stars

The central regions of galaxies are complex environments, rich in evolved and/or massive stars. For galaxies hosting an active galactic nucleus (AGN) with jets, the interaction of the jets with the winds of the stars within can lead to particle acceleration, and to extended high-energy emitting regions. We compute the non-thermal emission produced by the jet flow shocked by stellar winds on the jet scale, far from the jet-star direct interaction region. First, prescriptions for the winds of the relevant stellar populations in different types of galaxies are obtained. The scenarios adopted include galaxies with their central regions dominated by old or young stellar populations, and with jets of different power. Then, we estimate the available energy to accelerate particles in the jet shock, and compute the transport and energy evolution of the accelerated electrons, plus their synchrotron and inverse Compton emission, in the shocked flow along the jet. A significant fraction of the jet energy, $\sim 0.1-10$\%, can potentially be available for the particles accelerated in jet-wind shocks in the studied cases. The non-thermal particles can produce most of the high-energy radiation on jet scales, far from the jet shock region. This high-energy emission will be strongly enhanced in jets aligned with the line of sight due to Doppler boosting effects. The interaction of relativistic jets with stellar winds may contribute significantly to the persistent high-energy emission in some AGNs with jets. However, in the particular case of M87, this component seems too low to explain the observed gamma-ray fluxes.Comment: 15 pages, 11 figures. Accepted to be published in A&

Current self-oscillations, spikes and crossover between charge monopole and dipole waves in semiconductor superlattices

Self-sustained current oscillations in weakly-coupled superlattices are studied by means of a self-consistent microscopic model of sequential tunneling including boundary conditions naturally. Well-to-well hopping and recycling of charge monopole domain walls produce current spikes (high frequency modulation) superimposed on the oscillation. For highly doped injecting contacts, the self-oscillations are due to dynamics of monopoles. As the contact doping decreases, a lower-frequency oscillatory mode due to recycling and motion of charge dipoles is predicted. For low contact doping, this mode dominates and monopole oscillations disappear. At intermediate doping, both oscillation modes coexist as stable solutions and hysteresis between them is possible.Comment: 4 pages, 4 figure

A Generic Four-step Methodology For Institutional Analysis

The central hypothesis of this paper is that there may be situations in which the traditional approach to institutional analysis is of limited applicability. Such an approach, which has been called 'comparative institutional analysis', consists of comparing institutional environments and institutional arrangements in terms of specific economic or other efficiency criteria to see which one performs better. However, because of limitations to accurately predict the future performance of alternative institutional settings, comparisons are not always possible. Furthermore, in most cases the only information available is the performance of the current institutional setting. To account for this methodological deficiency, a generic methodology for institutional analysis, which consists of four steps (institutional structure, institutional efficiency, institutional choice, and institutional change), is proposed in this paper. Accordingly, the emphasis switches from evaluating alternative institutional choices to improving current scenarios. To show the validity of this methodology, some results of its application to a case study are presented. Although more research on this four-step methodology is needed, it proved to be robust when applied to the analysis of the governance of irrigated agriculture in the Peninsula of Santa Elena, Ecuador.New Institutional Economics, Governance structures, Institutional Change., Institutional and Behavioral Economics, B52, D02, Q25,