Pair-transfer probability in open- and closed-shell Sn isotopes

Approximations made to estimate two-nucleon transfer probabilities in ground-state to ground-state transitions and physical interpretation of these probabilities are discussed. Probabilities are often calculated by approximating both ground states, of the initial nucleus A and of the final nucleus A\pm 2 by the same quasiparticle vacuum. We analyze two improvements of this approach. First, the effect of using two different ground states with average numbers of particles A and A\pm2 is quantified. Second, by using projection techniques, the role of particle number restoration is analyzed. Our analysis shows that the improved treatment plays a role close to magicity, leading to an enhancement of the pair-transfer probability. In mid-shell regions, part of the error made by approximating the initial and final ground states by a single vacuum is compensated by projecting onto good particle number. Surface effects are analyzed by using pairing interactions with a different volume-to-surface mixing. Finally, a simple expression of the pair-transfer probability is given in terms of occupation probabilities in the canonical basis. We show that, in the canonical basis formulation, surface effects which are visible in the transfer probability are related to the fragmentation of single-particle occupancies close to the Fermi energy. This provides a complementary interpretation with respect to the standard quasiparticle representation where surface effects are generated by the integrated radial profiles of the contributing wave functions.Comment: 12 pages, 7 figure

The effect of metacognitive strategy instruction on L2 learner beliefs and listening skills

This pilot study investigated the effect of semester-long strategy-based instruction on learner beliefs and skills in the processing of aural input by adult learners of English as a second language at metacognitive and procedural levels. The study addressed two frequently encountered learner beliefs thought to impede L2 processing of aural input: The little words aren’t important; intonation is merely decorative. Working on the premise that learner beliefs underpin learner strategies for processing aural input and are reflected in learner productive and receptive skills, pre- and post-instruction instruments measured both learners’ awareness of connected speech processes and the functions of intonation, and their ability to segment a continuous speech stream, and to process utterances for speaker intent. Findings using repeated measures analysis of variance support strategy-based metacognitive training in connected speech and stress and intonation to promote listening skills awareness, aid word segmentation, and facilitate understanding utterance content and intended meaning.Published versio

To what extent would the poorest consumers nutritionally and socially benefit from a global food tax and subsidy reform ? A framed field experiment based on daily food intake

In this paper we propose a new method in experimental economics, designed to evaluate the effectiveness of public policy incentives aimed at altering consumer behaviors. We apply this method to wide-ranging policies on food prices, which use subsidies to increase the consumption of healthy products and taxes to reduce that of unhealthy ones. Our protocol allows for observation of an individual’s daily food consumption before and after the policy. We examine two separate policies: the one subsidizes fruit and vegetables, while the other one combines taxes and subsidies. We measure their nutritional and economic impacts on the choices of low-income French consumers, compared to a reference group. Both policies have a positive effect on the nutritional quality of food choices of the two groups but initial gaps widen, especially with the subsidies. In the low-income group this can be explained by an initially unfavorable pattern and by weaker price elasticities. The redistributive effects are therefore doubly regressive. Moreover, the individual price elasticities, that the experimental approach enables us to measure, show widely diverse behaviors. They are counter-effective for close to 40% of our sample of poor women.OBESITY;PUBLIC POLICY;SOCIAL INEQUALITIES;POVERTY;INCOME REDISTRIBUTION;REGRESSIVE TAX;INDIVIDUALIZED PRICE INDEX;NUTRITIONAL TAX SYSTEM;FOOD TAX

Interest of site-specific pollution control policies

Owing to increasing environmental concerns the current trend is to bend technical production systems in order to adapt them to the specific characteristics of the milieu and diversify them. Inherent to such dynamics is the issue of how to design the accompanying environmental policies. Theoretically, spatially targeted environmental policies are considered optimal, since economic agents tune their efforts according to the sensitivity of the milieu where they operate. But, according to empirical analyses, this advantage is undermined by the high cost of implementation, monitoring and enforcement. This paper outlines the conditions required for site-specific policies to be effective at least cost. Our starting point is the nitrate pollution of water from agriculture, which varies according to climate, soil type and agricultural production system. Farm management practices enabling to reduce pollution depend on this variability. An interdisciplinary study of the efficiency of differentiating the way this pollution is regulated was carried out on two sites in France. It focussed on assessing the importance of spatial variability in physical parameters and in private and social costs.NONPOINT POLLUTION; SITE SPECIFIC TECHNOLOGY; SITE SPECIFIC ENVIRONMENTAL POLICY; ABATEMENT COST; TRANSACTION COST

Entanglement Entropy and Full Counting Statistics for 2d2d-Rotating Trapped Fermions

We consider $N$ non-interacting fermions in a $2d$ harmonic potential of trapping frequency $\omega$ and in a rotating frame at angular frequency $\Omega$, with $0<\omega - \Omega\ll \omega$. At zero temperature, the fermions are in the non-degenerate lowest Landau level and their positions are in one to one correspondence with the eigenvalues of an $N\times N$ complex Ginibre matrix. For large $N$, the fermion density is uniform over the disk of radius $\sqrt{N}$ centered at the origin and vanishes outside this disk. We compute exactly, for any finite $N$, the R\'enyi entanglement entropy of order $q$, $S_q(N,r)$, as well as the cumulants of order $p$, $\langle{N_r^{p}}\rangle_c$, of the number of fermions $N_r$ in a disk of radius $r$ centered at the origin. For $N \gg 1$, in the (extended) bulk, i.e., for $0 < r/\sqrt{N} < 1$, we show that $S_q(N,r)$ is proportional to the number variance ${\rm Var}\,(N_r)$, despite the non-Gaussian fluctuations of $N_r$. This relation breaks down at the edge of the fermion density, for $r \approx \sqrt{N}$, where we show analytically that $S_q(N,r)$ and ${\rm Var}\,(N_r)$ have a different $r$-dependence.Comment: 6 pages + 7 pages (Supplementary material), 2 Figure

Extremes of 2d2d Coulomb gas: universal intermediate deviation regime

In this paper, we study the extreme statistics in the complex Ginibre ensemble of $N \times N$ random matrices with complex Gaussian entries, but with no other symmetries. All the $N$ eigenvalues are complex random variables and their joint distribution can be interpreted as a $2d$ Coulomb gas with a logarithmic repulsion between any pair of particles and in presence of a confining harmonic potential $v(r) \propto r^2$. We study the statistics of the eigenvalue with the largest modulus $r_{\max}$ in the complex plane. The typical and large fluctuations of $r_{\max}$ around its mean had been studied before, and they match smoothly to the right of the mean. However, it remained a puzzle to understand why the large and typical fluctuations to the left of the mean did not match. In this paper, we show that there is indeed an intermediate fluctuation regime that interpolates smoothly between the large and the typical fluctuations to the left of the mean. Moreover, we compute explicitly this "intermediate deviation function" (IDF) and show that it is universal, i.e. independent of the confining potential $v(r)$ as long as it is spherically symmetric and increases faster than $\ln r^2$ for large $r$ with an unbounded support. If the confining potential $v(r)$ has a finite support, i.e. becomes infinite beyond a finite radius, we show via explicit computation that the corresponding IDF is different. Interestingly, in the borderline case where the confining potential grows very slowly as $v(r) \sim \ln r^2$ for $r \gg 1$ with an unbounded support, the intermediate regime disappears and there is a smooth matching between the central part and the left large deviation regime.Comment: 36 pages, 7 figure

Voltage induced control and magnetoresistance of noncollinear frustrated magnets

Noncollinear frustrated magnets are proposed as a new class of spintronic materials with high magnetoresistance which can be controlled with relatively small applied voltages. It is demonstrated that their magnetic configuration strongly depends on position of the Fermi energy and applied voltage. The voltage induced control of noncollinear frustrated materials (VCFM) can be seen as a way to intrinsic control of colossal magnetoresistance (CMR) and is the bulk material counterpart of spin transfer torque concept used to control giant magnetoresistance in layered spin-valve structures.Comment: 4 pages, 4 figure