How large is the spreading width of a superdeformed band?

Recent models of the decay out of superdeformed bands can broadly be divided into two categories. One approach is based on the similarity between the tunneling process involved in the decay and that involved in the fusion of heavy ions, and builds on the formalism of nuclear reaction theory. The other arises from an analogy between the superdeformed decay and transport between coupled quantum dots. These models suggest conflicting values for the spreading width of the decaying superdeformed states. In this paper, the decay of superdeformed bands in the five even-even nuclei in which the SD excitation energies have been determined experimentally is considered in the framework of both approaches, and the significance of the difference in the resulting spreading widths is considered. The results of the two models are also compared to tunneling widths estimated from previous barrier height predictions and a parabolic approximation to the barrier shape

Dynamic behavior of rectangular plates and cylindrical shells

Numerical integration technique for determining dynamic response of rectangular plates and cylindrical shells subjected to stationary and constant velocity load

Advancing Shannon entropy for measuring diversity in systems

From economic inequality and species diversity to power laws and the analysis of multiple trends and trajectories, diversity within systems is a major issue for science. Part of the challenge is measuring it. Shannon entropy H has been used to re-think diversity within probability distributions, based on the notion of information. However, there are two major limitations to Shannon's approach. First, it cannot be used to compare diversity distributions that have different levels of scale. Second, it cannot be used to compare parts of diversity distributions to the whole. To address these limitations, we introduce a re-normalization of probability distributions based on the notion of case-based entropy Cc as a function of the cumulative probability c. Given a probability density p(x), Cc measures the diversity of the distribution up to a cumulative probability of c, by computing the length or support of an equivalent uniform distribution that has the same Shannon information as the conditional distribution of ^pc(x) up to cumulative probability c. We illustrate the utility of our approach by re-normalizing and comparing three well-known energy distributions in physics, namely, the Maxwell-Boltzmann, Bose-Einstein and Fermi-Dirac distributions for energy of sub-atomic particles. The comparison shows that Cc is a vast improvement over H as it provides a scale-free comparison of these diversity distributions and also allows for a comparison between parts of these diversity distributions

Onboard sampling of the rockfish and lingcod commerical passenger fishing vessel industry in northern and central California, 1992

In 1992 fishery technicians sampled 230 commercial passenger fishing vessel (CPFV) trips targeting rockfish and lingcod from the port areas of Fort Bragg, Bodega Bay, San Francisco, Monterey, and Morro Bay. The skippers of 44 vessels, and 2,190 anglers, cooperated in the study. Species composition by port area and month, catch-per-unit-effort, mean length, and length frequency of lingcod and the 18 most frequently observed rockfish species are presented, as well as fishing effort relative to time, depth, and distance from port. Total catch estimates based on unadjusted and adjusted logbook records are summarized. Average catch of kept fish per angler day was 12.6 and average catch of kept fish per angler hour was 4.0. A continuing trend of an increasing frequency of trips to deep (> 40 fm) locations was observed in the Bodega Bay, San Francisco, and Monterey areas. Bodega Bay and San Francisco showed the highest frequency of trips to distant locations. Sixty species comprised of 29,731 fish were observed caught during the study. Rockfish comprised 93.5% by number of the total observed catch. The five most frequently observed species were blue, yellowtail, widow and rosy rockfishes, and bocaccio, with lingcod ranking eighth. CPFV angler success, as determined by catch per angler hour, generally increased in all ports in 1992 compared to previous 1988-91 data (Reilly et al. 1993). However, port-specific areas of major concern were identified for chilipepper, lingcod, and black rockfish, and to a lesser extent brown, canary, vermilion, yelloweye, widow and greenspotted rockfishes. These areas of concern included steadily declining catch rate, steadily declining mean length, and/or a high percentage of sexually immature fish in the sampled catch. Recent sampling of the commercial hook-and-line fishery in northern and central California indicates that most rockfishes taken by CPFV anglers are also harvested commercially. (105pp.

RISK RESEARCH AND PUBLIC OUTREACH: A TALE OF TWO CULTURES?

Agricultural economists have been challenged in recent years, by voices inside and outside the profession, to evaluate the integrity of the operational bridge between research and extension activities in the land grant system. This essay investigates links between the work of risk researchers and outreach programs. Survey results indicate that (a) a significant number of risk researchers are involved in extension activities; (b) extension economists are less frequently involved in risk research than their colleagues with no extension appointment; (c) full-time extension economists use less sophisticated risk tools in their outreach efforts than used in their research; and (d) all respondents, regardless of appointment, see a need for more applied risk analysis. Major challenges include a lack of financial support to close the data gap and to conduct relevant applied analysis present major communication challenges.Teaching/Communication/Extension/Profession,

Methods and apparatus employing vibratory energy for wrenching Patent

Ultrasonic wrench for applying vibratory energy to mechanical fastener

Groundwater Conservation Policy in Agriculture

Transboundary water conflicts between urban and rural populations often center on water use in the agricultural sector. Public officials may select a water conservation policy as the primary tool for reducing agricultural water use with the goal to improve water availability to urban areas and future generations. The Groundwater Management Act of 1980 (GMA) in Arizona was designed, in part, to induce water conservation in irrigated agriculture to sustain economic growth in an arid climate. Our mixed-method evaluation design merges qualitative, interview-based information with an estimated water demand function using panel data. We find that the GMA began with a flawed design and evolved through political circumstances into a ineffective water conservation tool. We explain nearly all water use in Arizona's agricultural sector from 1984-2002 using prices and weather data. We found no statistical evidence that the management plans of the GMA directly contributed to reduced water demand in Arizona's agricultural sector over the study period.Impact assessment, public policy, irrigation, water conservation, Resource /Energy Economics and Policy,