Subgeometric ergodicity of strong Markov processes

We derive sufficient conditions for subgeometric f-ergodicity of strongly Markovian processes. We first propose a criterion based on modulated moment of some delayed return-time to a petite set. We then formulate a criterion for polynomial f-ergodicity in terms of a drift condition on the generator. Applications to specific processes are considered, including Langevin tempered diffusions on R^n and storage models.Comment: Published at http://dx.doi.org/10.1214/105051605000000115 in the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

PQCD Analysis of Parton-Hadron Duality

We propose an extraction of the running coupling constant of QCD in the infrared region from experimental data on deep inelastic inclusive scattering at Bjorken x -> 1. We first attempt a perturbative fit of the data that extends NLO PQCD evolution to large x values and final state invariant mass, W, in the resonance region. We include both target mass corrections and large x resummation effects. These effects are of order O(1/Q^2), and they improve the agreement with the Q^2 dependence of the data. Standard analyses require the presence of additional power corrections, or dynamical higher twists, to achieve a fully quantitative fit. Our analysis, however, is regulated by the value of the strong coupling in the infrared region that enters through large x resummation effects, and that can suppress, or absorb, higher twist effects. Large x data therefore indirectly provide a measurement of this quantity that can be compared to extractions from other observables.Comment: 10 pages, 3 figure

Three-dimensional computer model for the atmospheric general circulation experiment

An efficient, flexible, three-dimensional, hydrodynamic, computer code has been developed for a spherical cap geometry. The code will be used to simulate NASA's Atmospheric General Circulation Experiment (AGCE). The AGCE is a spherical, baroclinic experiment which will model the large-scale dynamics of our atmosphere; it has been proposed to NASA for future Spacelab flights. In the AGCE a radial dielectric body force will simulate gravity, with hot fluid tending to move outwards. In order that this force be dominant, the AGCE must be operated in a low gravity environment such as Spacelab. The full potential of the AGCE will only be realized by working in conjunction with an accurate computer model. Proposed experimental parameter settings will be checked first using model runs. Then actual experimental results will be compared with the model predictions. This interaction between experiment and theory will be very valuable in determining the nature of the AGCE flows and hence their relationship to analytical theories and actual atmospheric dynamics

Consideration of computer limitations in implementing on-line controls

A formal statement of the optimal control problem which includes the interval of dicretization as an optimization parameter, and extend this to include selection of a control algorithm as part of the optimization procedure, is formulated. The performance of the scalar linear system depends on the discretization interval. Discrete-time versions of the output feedback regulator and an optimal compensator, and the use of these results in presenting an example of a system for which fast partial-state-feedback control better minimizes a quadratic cost than either a full-state feedback control or a compensator, are developed

A New Method for Exposing Deposit Feeders to Contaminated Sediments for Food Chain Studies

(excerpt) The ubiquity and refractory nature of certain organic compounds, such as chlorinated pesticides and polychlorinated biphenyls (PCB\u27s), results in their accumulation in aquatic sediments (Holdrinet et al. 1978, Peck et al. 1980, Wang et al. 1979). Their continuous release from this reservoir through physico-chemical and biogenic processes to the overlying water column results in the accumulation of xenobiotic compounds in the food chain

Long-Wellesley & Publicity: The Role of Celebrity in the Public Sphere (1788-1832)

This thesis explores the relationship between celebrity and the public-sphere through a case study of the life of William Long-Wellesley (1788-1857). A junior member of the powerful and well-connected Wellesley family, Long-Wellesley married into the largest fortune in Regency Britain, became a Tory MP and enjoyed moderate success as an author. But he owed his celebrity status to public curiosity about his rakish and extravagant lifestyle. A study of Long-Wellesley’s celebrity history is important because it enables an investigation into the framework of the public sphere. In the second half of the eighteenth-century a new form of public sphere emerged, partly as a result of the rise of urban intellectual middle-class society in Western Europe, especially in England. It has been argued that the collective engagement of private people, coming together in a ‘public sphere’, resulted in the formulation of ‘public opinion’ for the purpose of acting as a corrective authority to the state. The general scholarly consensus has therefore argued that public opinion belongs to the political sphere. This thesis sets out to challenge that premise, and the assumptions that underpin it, by demonstrating that public opinion was more culturally derived, and found its inspiration in publicity. The parameters of the public sphere in the late eighteenth and early nineteenth century were more broadly defined than the traditional political focus suggests. Instead, it will be established that audiences were stimulated through a wide variety of sources, including spectacle, novelty, and celebrity. This thesis aims to re-position celebrity in the public sphere, showing how it impacted upon public opinion. It focuses on the life of Long-Wellesley because he offers many examples of how celebrity was represented in Britain during the Regency period. His decision to create and distribute his own sensational narrative makes Long-Wellesley a worthy case study; not least because he was the chief purveyor of, rather than a helpless victim of, malicious rumour and gossip. He is a prime example of how non-political spectacle influenced public opinion and helped to change the moral climate

Development of and dynamic studies concerning a cable boom system prototype

The conception of a cable boom system for a scientific spin stabilized satellite led to a flat cable stowed on a drum with a flexlead without conversion to avoid slip rings and to facilitate automatic restowage from any state of deployment. Some dynamic features of the extended cable boom and especially the comparison between round and flat cables were investigated in a phenomenological study using a test rig capable of inducing lateral, torsional and thermal cycling disturbances separately or in any combination