La Memoria de Nuestra Tierra: Sites of Public Memory

Judith F. Baca, artist, educator, scholar/activist, and community arts pioneer, University of California, Los Angeles, explores an idea that is deceptively simple: the land has memory. She articulates this idea as much through images as words; indeed, images form the spine of the argument, specifically photographs of a mural along a flood control channel in the San Fernando Valley. Baca created this Great Wall of Los Angeles with people hungry to know forgotten histories of their land and inscribe them for the future. Each of these images excavates another layer of a complex story. Baca gives form to monuments that rise out of neighborhoods, rather than being imposed upon them. She and the people who live there co-create art works that become “sites of public memory,” as she vividly describes in these pages. This publication is based on the keynote Baca delivered at Imagining America’s 2008 national conference, Public Engagement in a Diverse America: Layers of Place, Movements of People

(Re)Counting the poor in Peru: a multidimensional approach

After an impressive 12 point reduction in Peruvian monetary poverty, questions have been raised about the extent in which these figures mask deprivation in several other aspects critical for human development. We propose using the Alkire-Foster multidimensional headcount to address this issue, and devise a simple comparison framework to measure the tension between the incidence of monetary poverty and the overall level of deprivation based on the multidimensional measure. We select six dimensions and their respective indicators for the Peruvian case, and apply this framework using data for 2004 and 2008. Results indicate that we now face a larger risk of classifying as non-poor individuals who still endure significant deprivation if we rely on the conventional monetary dimension. In addition, inter and intraregional comparisons show that deprivations endured by the multidimensional poor are similar across regions and concentrated on the health and dwelling conditions dimensions, in particular, on the lack of adequate water and sanitation services. This last result reveals an opportunity to focalize public investment efforts.Multidimensional poverty; monetary poverty; Peru.

Magnons in Ferromagnetic Metallic Manganites

Ferromagnetic (FM) manganites, a group of likely half-metallic oxides, are of special interest not only because they are a testing ground of the classical doubleexchange interaction mechanism for the colossal magnetoresistance, but also because they exhibit an extraordinary arena of emergent phenomena. These emergent phenomena are related to the complexity associated with strong interplay between charge, spin, orbital, and lattice. In this review, we focus on the use of inelastic neutron scattering to study the spin dynamics, mainly the magnon excitations in this class of FM metallic materials. In particular, we discussed the unusual magnon softening and damping near the Brillouin zone boundary in relatively narrow band compounds with strong Jahn-Teller lattice distortion and charge/orbital correlations. The anomalous behaviors of magnons in these compounds indicate the likelihood of cooperative excitations involving spin, lattice, as well as orbital degrees of freedom.Comment: published in J. Phys.: Cond. Matt. 20 figure

Strong Enhancement of the Critical Current at the Antiferromagnetic Transition in ErNi2B2C Single Crystals

We report on transport and magnetization measurements of the critical current density Jc in ErNi2B2C single crystals that show strongly enhanced vortex pinning at the Neel temperature TN and low applied fields. The height of the observed Jc peak decreases with increasing magnetic field in clear contrast with that of the peak effect found at the upper critical field. We also performed the first angular transport measurements of Jc ever conducted on this compound. They reveal the correlated nature of this pinning enhancement, which we attribute to the formation of antiphase boundaries at TN.Comment: 3 figure

Magnetic Interaction in the Geometrically Frustrated Triangular Lattice Antiferromagnet CuFeO2\rm CuFeO_2

The spin wave excitations of the geometrically frustrated triangular lattice antiferromagnet (TLA) $\rm CuFeO_2$ have been measured using high resolution inelastic neutron scattering. Antiferromagnetic interactions up to third nearest neighbors in the ab plane (J_1, J_2, J_3, with $J_2/J_1 \approx 0.44$ and $J_3/J_1 \approx 0.57$), as well as out-of-plane coupling (J_z, with $J_z/J_1 \approx 0.29$) are required to describe the spin wave dispersion relations, indicating a three dimensional character of the magnetic interactions. Two energy dips in the spin wave dispersion occur at the incommensurate wavevectors associated with multiferroic phase, and can be interpreted as dynamic precursors to the magnetoelectric behavior in this system.Comment: 4 pages, 4 figures, published in Phys. Rev. Let