Short- and intermediate-time behavior of the linear stress relaxation in semiflexible polymers

The linear viscoelasticity of semiflexible polymers is studied through Brownian Dynamics simulations covering a broad range of chain stiffness and time scales. Our results agree with existing theoretical predictions in the flexible and stiff limits; however, we find that over a wide intermediate-time window spanning several decades, the stress relaxation is described by a single power law t^(-alpha), with the exponent alpha apparently varying continuously from 1/2 for flexible chains, to 5/4 for stiff ones. Our study identifies the limits of validity of the t^(-3/4) power law at short times predicted by recent theories. An additional regime is identified, the "ultrastiff" chains, where this behavior disappears. In the absence of Brownian motion, the purely mechanical stress relaxation produces a t^(-3/4) power law for both short and intermediate times

THE WELFARE CONSEQUENCES OF CERTIFIED LABELING FOR CREDENCE ATTRIBUTES

Certified labeling for credence attributes is examined using the concepts of pooled and separating equilibria. The analysis addresses a latent credence good demand that differs from a conventional good demand by willingness to pay for the credence characteristic. Third-party certified labeling vertically differentiates the two products and a two separate markets replace a single pooled market. Market outcomes are examined theoretically and with empirical simulations. Costless labeling is net welfare improving, but impacts are highly asymmetric. Credence producers gain largely at the expense of conventional producers. Costly labeling may reduce welfare even with rather modest labeling costs.Marketing,

INFORMATION AS A DOUBLE-EDGE SWORD: IMPLICATIONS FOR FOOD STANDARDS AND LABELS

An analytical model is developed to examine product quality labeling. Prior to labeling all consumers are willing to pay a premium for the quality characteristic but product quality cannot be observed directly. If production costs are increasing, the total quantity produced may contain a mix of products - with and without the high-valued attribute. In the pooled equilibrium demand is influenced by perceptions of the product mix. After labels are introduced the market is separated into two sectors, conventional and high-valued. The economic implications of labels are examined by contrasting welfare in the separating equilibrium with welfare in the pooled equilibrium. Under the models' maintained assumptions the conventional sector loses welfare, while producers of the high-valued product experience gains. In addition, producers of the high-valued product may have incentives to promote costly labeling despite net-welfare losses.Marketing,

Breast Cancer: Modelling and Detection

This paper reviews a number of the mathematical models used in cancer modelling and then chooses a specific cancer, breast carcinoma, to illustrate how the modelling can be used in aiding detection. We then discuss mathematical models that underpin mammographic image analysis, which complements models of tumour growth and facilitates diagnosis and treatment of cancer. Mammographic images are notoriously difficult to interpret, and we give an overview of the primary image enhancement technologies that have been introduced, before focusing on a more detailed description of some of our own recent work on the use of physics-based modelling in mammography. This theoretical approach to image analysis yields a wealth of information that could be incorporated into the mathematical models, and we conclude by describing how current mathematical models might be enhanced by use of this information, and how these models in turn will help to meet some of the major challenges in cancer detection

INFORMATION AS A DOUBLE-EDGED SWORD: THE ECONOMIC AND WELFARE CONSEQUENCES OF CERTIFIED LABELING FOR CREDENCE ATTRIBUTES

Certified labeling for credence attributes is examined using the concepts of pooled and separating equilibria. Credence attributes are product features that cannot be experienced directly by consumer, features such as pesticide-free, dolphin-safe, hormone-free, and organic. Without labeling, the traded good is a mix of credence and conventional goods. With certified labeling, the pooled market is replaced with separate markets for the credence and conventional good. Market outcomes are examined theoretically and with empirical simulations. Costless labeling is net welfare improving, but impacts are highly asymmetric. Credence producers gain largely at the expense of conventional producers. Costly labeling may reduce welfare even with rather modest labeling costs.Marketing,

THE EFFECT OF HAZARDOUS WASTE SITES ON PROPERTY VALUES IN ZONES OF HIGH INDUSTRIAL ACTIVITY: A HEDONIC APPROACH

Hedonic pricing methods typically employ a distance-to-site variable to measure variation in exposure to environmental disamenities. Some environmental disamenities, like hazardous waste sites, may be spatially correlated with another prominent feature of the urban plain zones of industrial activity. In these cases, failure to account for industrial activity is hypothesized to bias coefficient estimates of the distance-to-site measure. The data set includes a distance-to-site measure as well as a distance-to-industrial measure. These measures allow for empirical estimations of the hedonic price function that distinguish the property value effect associated with exposure to hazard from the property value effect associated with industrial activity. The results suggest that failure to account for industrial activity will overstate the effect of hazardous waste sites on property values and inflate benefit estimates associated with hazardous waste clean-up. Key words: Superfund, Spatial Correlates, Industrial Activity, Hedonic Price FunctionSuperfund, Spatial Correlates, Industrial Activity, Hedonic Price Function, Environmental Economics and Policy, Land Economics/Use,

A nonlinear detection algorithm for periodic signals in gravitational wave detectors

We present an algorithm for the detection of periodic sources of gravitational waves with interferometric detectors that is based on a special symmetry of the problem: the contributions to the phase modulation of the signal from the earth rotation are exactly equal and opposite at any two instants of time separated by half a sidereal day; the corresponding is true for the contributions from the earth orbital motion for half a sidereal year, assuming a circular orbit. The addition of phases through multiplications of the shifted time series gives a demodulated signal; specific attention is given to the reduction of noise mixing resulting from these multiplications. We discuss the statistics of this algorithm for all-sky searches (which include a parameterization of the source spin-down), in particular its optimal sensitivity as a function of required computational power. Two specific examples of all-sky searches (broad-band and narrow-band) are explored numerically, and their performances are compared with the stack-slide technique (P. R. Brady, T. Creighton, Phys. Rev. D, 61, 082001).Comment: 9 pages, 3 figures, to appear in Phys. Rev.

Setting the Standard for Farmland Preservation: Do Preservation Criteria Motivate Citizen Support for Farmland Preservation?

The multifunctional set of services provided by farmland complicates the task of identifying which farmland should be preserved. For this reason many states and local governments establish criteria to rank and select parcels of farmland for protection. This study examines whether criteria commonly used by state programs to guide purchases of agricultural conservation easements influence public demand for farmland preservation. The results provide policy makers with additional information to assess current ranking criteria that set the standard for farmland preservation.Land Economics/Use,