Coherent population trapping in two-electron three-level systems with aligned spins

The possibility of coherent population trapping in two electron states with aligned spins (ortho-system) is evidenced. From the analysis of a three-level atomic system containing two electrons, and driven by the two laser fields needed for coherent population trapping, a conceptually new kind of two-electron dark state appears. The properties of this trapping are studied and are physically interpreted in terms of a dark hole, instead of a dark two-electron state. This technique, among many other applications, offers the possibility of measuring, with subnatural resolution, some superposition-state matrix-elements of the electron-electron correlation that due to their time dependent nature are inaccesible by standard measuring procedures.Comment: 10 pages and 4 figure

Shell model calculation of the beta- and beta+ partial halflifes of 54Mn and other unique second forbidden beta decays

The nucleus 54Mn has been observed in cosmic rays. In astrophysical environments it is fully stripped of its atomic electrons and its decay is dominated by the beta- branch to the 54Fe ground state. Application of 54Mn based chronometer to study the confinement of the iron group cosmic rays requires knowledge of the corresponding halflife, but its measurement is impossible at the present time. However, the branching ratio for the related beta+ decay of 54Mn was determined recently. We use the shell model with only a minimal truncation and calculate both beta+ and beta- decay rates of 54Mn. Good agreement for the beta+ branch suggests that the calculated partial halflife of the beta- decay, (4.94 \pm 0.06) x 10^5 years, should be reliable. However, this halflife is noticeably shorter than the range 1-2 x 10^6 y indicated by the fit based on the 54Mn abundance in cosmic rays. We also evaluate other known unique second forbidden beta decays from the nuclear p and sd shells (10Be, 22Na, and two decay branches of 26Al) and show that the shell model can describe them with reasonable accuracy as well.Comment: 4 pages, RevTeX, 2 figure

Does “soft conditionality” increase the impact of cash transfers on desired outcomes? Evidence from a randomized control trial in Lesotho

Cash transfers programs have been shown to have positive effects on a variety of outcomes. While much of the literature focuses on the role of conditionality in achieving desired impact, this paper focuses on the role of ‘soft conditionality’ implemented through both ‘labeling’ and ‘messaging’ in evaluating the impact of the Child Grants Program in Lesotho, an unconditional cash transfer targeting poor households with orphans and vulnerable children. Beneficiary households received a clear message that the transfer should be spent on the interest and needs of children. Our findings are based on a randomized experiment and suggest that ‘soft conditionality’ does play a strong role in increasing expenditure for children, especially on education, clothing and footwear. Results indicate in fact that transfer income is spent differently from general income as it exerts both an income and a substitution effect. This behavioral change is confirmed by comparing the ex-ante expected behaviors with the ex-post actual response to the program. We find that for expenditure categories linked to the wellbeing of children the ex-post response was much higher than the ex-ante expected behavior

Fundamental financial and managerial accounting concepts

1254 hlm. ; 28 cm