First-Passage Time Distribution and Non-Markovian Diffusion Dynamics of Protein Folding

We study the kinetics of protein folding via statistical energy landscape theory. We concentrate on the local-connectivity case, where the configurational changes can only occur among neighboring states, with the folding progress described in terms of an order parameter given by the fraction of native conformations. The non-Markovian diffusion dynamics is analyzed in detail and an expression for the mean first-passage time (MFPT) from non-native unfolded states to native folded state is obtained. It was found that the MFPT has a V-shaped dependence on the temperature. We also find that the MFPT is shortened as one increases the gap between the energy of the native and average non-native folded states relative to the fluctuations of the energy landscape. The second- and higher-order moments are studied to infer the first-passage time (FPT) distribution. At high temperature, the distribution becomes close to a Poisson distribution, while at low temperatures the distribution becomes a L\'evy-like distribution with power-law tails, indicating a non-self-averaging intermittent behavior of folding dynamics. We note the likely relevance of this result to single-molecule dynamics experiments, where a power law (L\'evy) distribution of the relaxation time of the underlined protein energy landscape is observed.Comment: 26 pages, 10 figure

Residential Appraisal and the Lending Process: A Survey of Issues

This article surveys mainly academic literature for issues concerning the use of appraisals in the residential lending process. The development of appraisal methodologies is reviewed, and the strengths and weaknesses of various appraisal techniques are assessed. Issues relating to the use of neighborhood characteristics in appraisals for lending purposes are also explored. Finally, institutional incentives that give rise to biased and self-serving appraisals and possible solutions to these incentive problems are examined.

Exponential Mixing for Retarded Stochastic Differential Equations

In this paper, we discuss exponential mixing property for Markovian semigroups generated by segment processes associated with several class of retarded Stochastic Differential Equations (SDEs) which cover SDEs with constant/variable/distributed time-lags. In particular, we investigate the exponential mixing property for (a) non-autonomous retarded SDEs by the Arzel\`{a}--Ascoli tightness characterization of the space \C equipped with the uniform topology (b) neutral SDEs with continuous sample paths by a generalized Razumikhin-type argument and a stability-in-distribution approach and (c) jump-diffusion retarded SDEs by the Kurtz criterion of tightness for the space \D endowed with the Skorohod topology.Comment: 20 page

ECONOMETRIC INVESTIGATION OF THE DYNAMIC EFFECTS OF THE 1983 PAYMENT-IN-KIND PROGRAM ON THE WHEAT ECONOMY

A stochastic, dynamic, and control-system econometric model of the wheat sector is developed to assess the effects of the Payment-in Kind program. Empirical results the complex dynamics of the responses. Reduced storage costs and deficiency payments for the U.S. government and increased income for wheat farmers are benefits from the PIK program in the short-run. Increased direct government transfers from the public to support the program were required. The long-run economic implications are not clearly desirable. This is due primarily to the highly sensitive international wheat market.Agricultural and Food Policy, Crop Production/Industries,