Non-magnetic pair-breaking effect on La(Fe_{1-x}Zn_{x})AsO_{0.85} studied by NMR and NQR

$^{75}$As and $^{139}$La NMR and nuclear quadrupole resonance (NQR) studies on Zn-substituted LaFeAsO$_{0.85}$ have been performed to investigate the Zn-impurity effects microscopically. Although superconductivity in LaFeAsO$_{0.85}$ disappears by 3% Zn substitution, we found that NMR/NQR spectra and NMR physical quantities in the normal state are hardly changed, indicating that the crystal structure and electronic states are not modified by Zn substitution. Our results suggest that the suppression of superconductivity by Zn substitution is not due to the change of the normal-state properties, but due to strong non-magnetic pair-breaking effect to superconductivity.Comment: 5 pages, 4 figures, This paper was chosen as "Paper of Editors' Suggestion

Incipient reproductive isolation between Drosophila nasuta and Drosophila albomicans

International audienc

Testing identifying assumptions in fuzzy regression discontinuity designs

We propose a new specification test for assessing the validity of fuzzy regression discontinuity designs (FRD-validity). We derive a new set of testable implications, characterized by a set of inequality restrictions on the joint distribution of observed outcomes and treatment status at the cut-off. We show that this new characterization exploits all the information in the data useful for detecting violations of FRD-validity. Our approach differs from, and complements existing approaches that test continuity of the distributions of running variables and baseline covariates at the cut-off since ours focuses on the distribution of the observed outcome and treatment status. We show that the proposed test has appealing statistical properties. It controls size in large sample uniformly over a large class of distributions, is consistent against all fixed alternatives, and has non-trivial power against some local alternatives. We apply our test to evaluate the validity of two FRD designs. The test does not reject the FRD-validity in the class size design studied by Angrist and Lavy (1999) and rejects in the insurance subsidy design for poor households in Colombia studied by Miller, Pinto, and Vera-Hernández (2013) for some outcome variables, while existing density tests suggest the opposite in each of the cases

Mineralogia de argilas em cambissolos do Sudoeste da Amazônia brasileira.

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Hydrogenation of Nd-Fe-B magnet powder under a high pressure of hydrogen

The hydrogenation of Nd2Fe14B under a high pressure of hydrogen has been investigated for the first time. At the heat-treatment temperature of 600 degree C, the almost complete decomposition of Nd2Fe14B into NdH2+x and alpha-Fe is observed, although a rather long heat-treatment time is necessary to achieve the sufficient hydrogenation. The desorption of hydrogen from NdH2+x does not occur in the furnace-cooling process.Comment: to appear in Results in Physic