Nuclear Structure Studies at ISOLDE and their Impact on the Astrophysical r-Process

The focus of the present review is the production of the heaviest elements in nature via the r-process. A correct understanding and modeling requires the knowledge of nuclear properties far from stability and a detailed prescription of the astrophysical environment. Experiments at CERN/ISOLDE have played a pioneering role in exploring the characteristics of nuclear structure in terms of masses and beta-decay properties. Initial examinations paid attention to far unstable nuclei with magic neutron numbers related to r-process peaks, while present activities are centered on the evolution of shell effects with the distance from the valley of stability. We first show in site-independent applications the effect of both types of nuclear properties on r-process abundances. Then, we explore the results of calculations related to two different `realistic' astrophysical sites, (i) the supernova neutrino wind and (ii) neutron star mergers. We close with a list of remaining theoretical and experimental challenges needed to overcome for a full understanding of the nature of the r-process, and the role CERN/ISOLDE can play in this process.Comment: LATEX, 38 pages, 16 figures, submitted to Hyperfine Interaction

Notes on Tacitus's Agricola

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The effect of bedrest on various parameters of physiological function. part v- dietary requirements

Effect of bedrest on various parameters of physiological function - nutritional requiremen

Chains of infinite order, chains with memory of variable length, and maps of the interval

We show how to construct a topological Markov map of the interval whose invariant probability measure is the stationary law of a given stochastic chain of infinite order. In particular we caracterize the maps corresponding to stochastic chains with memory of variable length. The problem treated here is the converse of the classical construction of the Gibbs formalism for Markov expanding maps of the interval

Use of the Chebyshev-Legendre quadrature set in discrete-ordinate codes

The Chebyshev-Legendre (C-L) quadrature set has been implemented in the neutron transport section of the TWODANT code. The C-L quadrature set has two advantages as compared to other quadrature sets. First, it is possible to easily generate S/sub N/ orders up to S/sub 100/ with weights that are positive. TWODANT has been used to carry out calculations with as many as 10,000 discrete directions with the C-L quadrature set. Second, a product C-L set or order N will integrate exactly all the terms in the scattering source arising from P/sub N-1/ scattering. For example, the S/sub 4/ set will correctly integrate all scattering source terms if a P/sub 3/ scattering approximation is used. In TWODANT, users normally use the current S/sub 8/ quadrature set in the belief that P/sub 3/ scattering will be treated correctly. The S/sub 8/ set consists of some 40 directions and many times results in problem models that require excessive computer memory. The C-L S/sub 4/ set integrates exactly all the source terms associated with a P/sub 3/ expansion and consists of only 16 discrete directions. The results of test calculations, using both the current set and the C-L set in TWODANT, indicate that when high-order scattering is not significant, the two sets give answers that are in good agreement. 3 refs

Refined forest land use classification with implications for United States national carbon accounting

The United States provides annual estimates of carbon sources and sinks as part of its National Green-house Gas Inventory (NGHGI). Within this effort, carbon stocks and fluxes are reported for six land use categories that are relevant to economic sectors and land use policy. The goal of this study is to develop methodologies that will allow the US to align with an internationally agreed upon forest land use definition which requires forest to be able to reach 5 m in height at maturity. Models to assess height potential are available for a majority of US forests except for woodland ecosystems. We develop a set of models to assess height potential in these systems. Our results suggest that ∼13.5 million ha of forests are unlikely to meet the international definition of forests due to environmental limitations to maximum attainable height. The incorporation of this height criteria in the NGHGI results in a carbon stock transfer of ∼848 Tg from the forest land use to woodland land use (a sub-category of grasslands) with minimal effect on sequestration rates. The development of a forest land use definition sensitive to climatic factors in this study enables a land use classification system that can be responsive to climate change effects on land uses themselves while being more consistent across a host of international and domestic carbon reporting efforts

Exploring Agricultural Production Systems and Their Fundamental Components with System Dynamics Modelling

Agricultural production in the United States is undergoing marked changes due to rapid shifts in consumer demands, input costs, and concerns for food safety and environmental impact. Agricultural production systems are comprised of multidimensional components and drivers that interact in complex ways to influence production sustainability. In a mixed-methods approach, we combine qualitative and quantitative data to develop and simulate a system dynamics model that explores the systemic interaction of these drivers on the economic, environmental and social sustainability of agricultural production. We then use this model to evaluate the role of each driver in determining the differences in sustainability between three distinct production systems: crops only, livestock only, and an integrated crops and livestock system. The result from these modelling efforts found that the greatest potential for sustainability existed with the crops only production system. While this study presents a stand-alone contribution to sector knowledge and practice, it encourages future research in this sector that employs similar systems-based methods to enable more sustainable practices and policies within agricultural production

On three topical aspects of the N=28 isotonic chain

The evolution of single-particle orbits along the N=28 isotonic chain is studied within the framework of a relativistic mean-field approximation. We focus on three topical aspects of the N=28 chain: (a) the emergence of a new magic number at Z=14; (b) the possible erosion of the N=28 shell; and (c) the weakening of the spin-orbit splitting among low-j neutron orbits. The present model supports the emergence of a robust Z=14 subshell gap in 48Ca, that persists as one reaches the neutron-rich isotone 42Si. Yet the proton removal from 48Ca results in a significant erosion of the N=28 shell in 42Si. Finally, the removal of s1/2 protons from 48Ca causes a ~50% reduction of the spin-orbit splitting among neutron p-orbitals in 42Si.Comment: 12 pages with 5 color figure