24 research outputs found
DDE, a Degradation Product of DDT, and Duration of Lactation in a Highly Exposed Area of Mexico
Correlated local distortions of the TlO layers in TlBaCuO: An x-ray absorption study
We have used the XAFS (x-ray-absorption fine structure) technique to
investigate the local structure about the Cu, Ba, and Tl atoms in orthorhombic
Tl-2201 with a superconducting transition temperature T=60 K. Our results
clearly show that the O(1), O(2), Cu, and Ba atoms are at their ideal sites as
given by the diffraction measurements, while the Tl and O(3) atoms are more
disordered than suggested by the average crystal structure. The Tl-Tl distance
at 3.5 \AA{ } between the TlO layers does not change, but the Tl-Tl distance at
3.9 \AA{ } within the TlO layer is not observed and the Tl-Ba and Ba-Tl peaks
are very broad. The shorter Tl-O(3) distance in the TlO layer is about 2.33
\AA, significantly shorter than the distance calculated with both the Tl and
O(3) atoms at their ideal sites ( 0 or ). A model based
on these results shows that the Tl atom is displaced along the
directions from its ideal site by about 0.11 \AA; the displacements of
neighboring Tl atoms are correlated. The O(3) atom is shifted from the $4e$
site by about 0.53 \AA{ } roughly along the directions. A comparison of
the Tl L-edge XAFS spectra from three samples, with T=60 K, 76 K,
and 89 K, shows that the O environment around the Tl atom is sensitive to T
while the Tl local displacement is insensitive to T and the structural
symmetry. These conclusions are compared with other experimental results and
the implications for charge transfer and superconductivity are discussed. This
paper has been submitted to Phys. Rev. B.Comment: 20 pages plus 14 ps figures, REVTEX 3.
Integrating genetics and epigenetics in breast cancer: biological insights, experimental, computational methods and therapeutic potential
Increases in Breastfeeding Duration Observed in Latin America and the Caribbean and The Role of Maternal Demographic and Healthcare Characteristics
The Portuguese Version of the Breastfeeding Self-Efficacy ScaleâShort Form
The objective of this study was to translate and psychometrically assess a Portuguese version of the Breastfeeding Self-Efficacy ScaleâShort Form (BSES-SF). The original English version of the BSES-SF was translated to Portuguese and tested among a sample of 89 mothers in southern Brazil from the 2nd to 12th postpartum week followed by face-to-face interviews. The mean total score of the Portuguese version of the BSES-SF was 63.6 ± 6.22. The reliability analysis of each item in the scale attained significant Cronbachâs alphas of 0.63 or superior. The Cronbachâs alpha generated by the entire range of 14 questions was 0.71. A factor analysis identified one factor that contributed to 20% of the variance. This study demonstrates that the original English version of the BSES-SF was successfully adapted to Portuguese. The Portuguese version of the BSES-SF constitutes a reliable research instrument for evaluating breastfeeding self-efficacy in Brazil