Two-particle spatial correlations in superfluid nuclei

We discuss the effect of pairing on two-neutron space correlations in deformed nuclei. The spatial correlations are described by the pairing tensor in coordinate space calculated in the HFB approach. The calculations are done using the D1S Gogny force. We show that the pairing tensor has a rather small extension in the relative coordinate, a feature observed earlier in spherical nuclei. It is pointed out that in deformed nuclei the coherence length corresponding to the pairing tensor has a pattern similar to what we have found previously in spherical nuclei, i.e., it is maximal in the interior of the nucleus and then it is decreasing rather fast in the surface region where it reaches a minimal value of about 2 fm. This minimal value of the coherence length in the surface is essentially determined by the finite size properties of single-particle states in the vicinity of the chemical potential and has little to do with enhanced pairing correlations in the nuclear surface. It is shown that in nuclei the coherence length is not a good indicator of the intensity of pairing correlations. This feature is contrasted with the situation in infinite matter.Comment: 14 pages, 17 figures, submitted to PR

Program logics for homogeneous meta-programming.

A meta-program is a program that generates or manipulates another program; in homogeneous meta-programming, a program may generate new parts of, or manipulate, itself. Meta-programming has been used extensively since macros were introduced to Lisp, yet we have little idea how formally to reason about metaprograms. This paper provides the first program logics for homogeneous metaprogramming – using a variant of MiniMLe by Davies and Pfenning as underlying meta-programming language.We show the applicability of our approach by reasoning about example meta-programs from the literature. We also demonstrate that our logics are relatively complete in the sense of Cook, enable the inductive derivation of characteristic formulae, and exactly capture the observational properties induced by the operational semantics

Convergence of Particle-Hole Expansions for the Description of Nuclear Correlations

The convergence properties of a multiparticle-multihole (mp-mh) configuration mixing approach whose purpose is to describe ground state correlations in nuclei without particle number and Pauli violations is investigated in the case of an exactly solvable pairing hamiltonian. Two different truncation schemes are tested by looking at quantities as correlation energies and single-particle occupation probabilities. Results show that pairing correlations present in usual superfluid nuclei can be accurately described using up to 6 particle-6 hole excitations, a convergence fast enought for envisaging extensions to fully microscopic calculations.Comment: 8 pages, 4 figure

The effects of geographic expansion on bank efficiency

We assess the effects of geographic expansion on bank efficiency using cost and profit efficiency for over 7,000 U.S. banks, 1993-1998. We find that parent organizations exercise some control over the efficiency of their affiliates, although this control tends to dissipate with distance to the affiliate. However, on average, distance-related efficiency effects tend to be modest, suggesting that some efficient organizations can overcome any effects of distance. The results imply there may be no particular optimal geographic scope for banking organizations - some may operate efficiently within a single region, while others may operate efficiently on a nationwide or international basis.Bank mergers ; Financial institutions ; Banks and banking - Costs

Explaining the dramatic changes in performance of U.S. banks: technological change, deregulation, and dynamic changes in competition.

The authors investigate the effects of technological change, deregulation, and dynamic changes in competition on the performance of U.S. banks. The authors' most striking result is that during 1991-1997, cost productivity worsened while profit productivity improved substantially, particularly for banks engaging in mergers. The data are consistent with the hypothesis that banks tried to maximize profits by raising revenues as well as reducing costs. Banks appeared to provide additional or higher quality services that raised costs but also raised revenues by more than the cost increases. The results suggest that methods that exclude revenues when assessing performance may be misleadingBanks and banking ; Bank mergers

Small business credit scoring and credit availability

U.S. commercial banks are increasingly using credit scoring models to underwrite small business credits. This paper discusses this technology, evaluates the research findings on the effects of this technology on small business credit availability, and links these findings to a number of research and public policy issues.

The impact of retirement on physical activity

Most adults do not achieve the levels of physical activity currently recommended for a healthy lifestyle. Population surveys suggest that there is a linear decline of activity levels with age, yet physical activity has many health benefits for older adults. If these are to be more widely adopted among older people, health policy and promotion require an understanding of the factors that influence decreasing activity with age. This study examined the patterns of physical activity of 699 participants in the West of Scotland Twenty-07 Study who were aged 60 years when interviewed in 1991 and followed up four to five years later. It examined the factors that influenced whether or not the subjects achieved currently recommended levels of activity, by applying random effects models with a seasonal adjustment. It was found that higher levels of physical activity associated with a healthier lifestyle, and that socio-economic factors played a minor role in determining the level of physical activity. A substantial amount of physical activity occurred at work but was lost by those who had retired, for while those who were not working were more physically active at home or at leisure than those in work, the majority of the sample did too little physical activity outside work to compensate for the loss of work-based activity. One conclusion is that health promotion initiatives that encourage people to become more physically active should be targeted at those who are about to retire

Global integration in the banking industry

Lowered regulatory barriers and advances in technology have reduced the cost of supplying banking services across borders. At the same time, growth in activity by multinational corporations has increased the demand for international financial services. As a result, many observers believe that global integration is under way in the banking industry, that banks are expanding their reach across borders, and that many banking markets will therefore develop large foreign components. The authors report on a study conducted by them, along with Qinglei Dai and Steven Ongena, that examined the nationality and international reach of banks that provide short-term financial services across Europe to affiliates of multinational corporations. The present article also looks at time-series data that provide a more recent look at the progress of integration in Europe. Based on a 1996 survey of more than 2,000 affiliates, the study found that an affiliate is most likely to choose a bank headquartered in the nation in which it is operating (a host-nation bank) rather than a bank headquartered in the home country of the affiliate or in a third nation. The affiliate is also more likely to select a bank limited to local or regional operations rather than one with global reach. The findings are consistent with the proposition that affiliates most value a bank that understands the culture, business practices, and regulatory conditions of the country in which the affiliate operates, and that host-nation banks possess a competitive advantage over other banks in this regard. The time-series data--on syndicated loans, foreign bank claims, and the dispersion of consumer goods prices across Europe--are also consistent with the picture drawn from the 1996 survey. The article concludes that banking markets evidently need not become more integrated even as economic activity otherwise becomes increasingly global.Banks and banking ; International finance

Risk-based capital and deposit insurance reform

Risk-based capital (RBC) is an important component of deposit insurance reform. This paper provides an empirical analysis of the new 1992 RBC bank standards, applying them to data on virtually all U.S. banks from 1982 to 1989. The data reveal strong associations between several measures of future bank performance (including bankruptcy) and the RBC relative risk weights. These associations suggest that the weights constitute a significant improvement over the old capital standards, although there are several instances in which the weights for specific categories appear to be out of line with the performance results. Tests of the informational value of passing or failing the new and old capital standards show that both have independent information, but that the new RBC standards better predict future bank performance problems. The data also indicate that, in contrast to the old standards, the RBC capital burden falls much more heavily on large banks. As a result, banks representing more than one-fourth of all bank assets would have failed the new RBC standards as of 1989. The new standards are also more stringent overall. More banks would have failed the new standards than the old ones, with larger average capital deficiencies.Deposit insurance ; Bank supervision ; Bank capital