6 research outputs found
Atomic transition frequencies, isotope shifts, and sensitivity to variation of the fine structure constant for studies of quasar absorption spectra
Theories unifying gravity with other interactions suggest spatial and
temporal variation of fundamental "constants" in the Universe. A change in the
fine structure constant, alpha, could be detected via shifts in the frequencies
of atomic transitions in quasar absorption systems. Recent studies using 140
absorption systems from the Keck telescope and 153 from the Very Large
Telescope, suggest that alpha varies spatially. That is, in one direction on
the sky alpha seems to have been smaller at the time of absorption, while in
the opposite direction it seems to have been larger.
To continue this study we need accurate laboratory measurements of atomic
transition frequencies. The aim of this paper is to provide a compilation of
transitions of importance to the search for alpha variation. They are E1
transitions to the ground state in several different atoms and ions, with
wavelengths ranging from around 900 - 6000 A, and require an accuracy of better
than 10^{-4} A. We discuss isotope shift measurements that are needed in order
to resolve systematic effects in the study. The coefficients of sensitivity to
alpha-variation (q) are also presented.Comment: Includes updated version of the "alpha line" lis
Returns to investment in education: a further update
Returns to investment in education based on human capital theory have been estimated since the late 1950s. In the 40-plus year history of estimates of returns to investment in education, there have been several reviews of the empirical results in attempts to establish patterns. Many more estimates from a wide variety of countries, including over-time evidence, and estimates based on new econometric techniques, reaffirm the importance of human capital theory. This paper reviews and presents the latest estimates and patterns as found in the literature at the turn of the century. However, because the availability of rate of return estimates has grown exponentially, we include a new section on the need for selectivity in comparing returns to investment in education and establishing related patterns.
Are Lifestyle Interventions in Primary Care Cost-Effective? : An Analysis Based on a Markov Model, Differences-In-Differences Approach and the Swedish Björknäs Study
Background: Lifestyle interventions affect patients' risk factors for metabolic syndrome (MeSy), a pre-stage to cardiovascular diseases, diabetes and related complications. An effective lifestyle intervention is the Swedish Bjorknas intervention, a 3-year randomized controlled trial in primary care for MeSy patients. To include future disease-related cost and health consequences in a cost-effectiveness analysis, a simulation model was used to estimate the short-term (3-year) and long-term (lifelong) cost-effectiveness of the Bjorknas study. Methodology/Principal Findings: A Markov micro-simulation model was used to predict the cost and quality-adjusted life years (QALYs) for MeSy-related diseases based on ten risk factors. Model inputs were levels of individual risk factors at baseline and at the third year. The model estimated short-term and long-term costs and QALYs for the intervention and control groups. The cost-effectiveness of the intervention was assessed using differences-in-differences approach to compare the changes between the groups in the health care and societal perspectives, using a 3% discount rate. A 95% confidence interval (CI), based on bootstrapping, and sensitivity analyses describe the uncertainty in the estimates. In the short-term, costs are predicted to increase over time in both groups, but less in the intervention group, resulting in an average cost saving/reduction of US 1= six point five seven SEK) and US-7,300 (95% CI: US-1,000) in the societal, and US-5,400 to US 211 per participant, the intervention would result in cost saving. Furthermore, in the long-term an estimated 0.46 QALYs (95% CI: 0.12 to 0.69) per participant would be gained. Conclusions/Significance: The Swedish Bjorknas study appears to reduce demands on societal and health care resources and increase health-related quality of life
How job and skill shortages affect the UK
Are we living in the "golden age" of cosmology? Are we close to understanding the nature of the unknown ingredients of the currently most accepted cosmological model and the physics of the early Universe? Or are we instead approaching a paradigm shift? What is dark matter and does it exist? How is it distributed around galaxies and clusters? Is the scientific community open to alternative ideas that may prompt a new scientific revolution - as the Copernican revolution did in Galileo's time? Do other types of supernovae exist that can be of interest for cosmology? Why have quasars never been effectively used as standard candles? Can you tell us about the scientific adventure of COBE? How does the extraction of the Cosmic Microwave Background anisotropy depend on the subtraction of the various astrophysical foregrounds? These, among many others, are the astrophysical, philosophical and sociological questions surrounding modern cosmology and the scientific community that Mauro D'Onofrio and Carlo Burigana pose to some of the most prominent cosmologists of our time. Triggered by these questions and in the spirit of Galileo's book "Dialogue Concerning the Two Chief World Systems" the roughly 40 interview partners reply in the form of essays, with a critical frankness not normally found in reviews, monographs or textbooks