The Wealth and Poverty of Widows: Assets Before and After the Husband's Death

We verify that widows are much more likely than couples to be poor and that they make up a large proportion of the poor elderly; 80 percent are widows or other single individuals. Then we seek to explain why the single elderly are poor, with emphasis on widows. We do this by tracing back over time their financial status, using the Longitudinal Retirement History Survey. The death of the husband very often induces the poverty of the surviving spouse, even though the married couple was not poor. While only about 9 percent of prior couples are poor, approximately 35 percent of the subsequent widows are. A large proportion of the wealth of the couple is lost when the husband dies. In addition we find that: (1) the prior households of poor widows earned and saved less than the prior households of non-poor widows, (2) more of the smaller accumulated wealth was lost at the death of the husband, (3) the absence of survivorship benefits or life insurance insured that the loss in wealth would leave the widow poor thereafter.

Ab initio calculation of the anomalous Hall conductivity by Wannier interpolation

The intrinsic anomalous Hall effect in ferromagnets depends on subtle spin-orbit-induced effects in the electronic structure, and recent ab-initio studies found that it was necessary to sample the Brillouin zone at millions of k-points to converge the calculation. We present an efficient first-principles approach for computing the anomalous Hall conductivity. We start out by performing a conventional electronic-structure calculation including spin-orbit coupling on a uniform and relatively coarse k-point mesh. From the resulting Bloch states, maximally-localized Wannier functions are constructed which reproduce the ab-initio states up to the Fermi level. The Hamiltonian and position-operator matrix elements, needed to represent the energy bands and Berry curvatures, are then set up between the Wannier orbitals. This completes the first stage of the calculation, whereby the low-energy ab-initio problem is transformed into an effective tight-binding form. The second stage only involves Fourier transforms and unitary transformations of the small matrices set up in the first stage. With these inexpensive operations, the quantities of interest are interpolated onto a dense k-point mesh and used to evaluate the anomalous Hall conductivity as a Brillouin zone integral. The present scheme, which also avoids the cumbersome summation over all unoccupied states in the Kubo formula, is applied to bcc Fe, giving excellent agreement with conventional, less efficient first-principles calculations. Remarkably, we find that more than 99% of the effect can be recovered by keeping a set of terms depending only on the Hamiltonian matrix elements, not on matrix elements of the position operator.Comment: 16 pages, 7 figure

Spectral and Fermi surface properties from Wannier interpolation

We present an efficient first-principles approach for calculating Fermi surface averages and spectral properties of solids, and use it to compute the low-field Hall coefficient of several cubic metals and the magnetic circular dichroism of iron. The first step is to perform a conventional first-principles calculation and store the low-lying Bloch functions evaluated on a uniform grid of k-points in the Brillouin zone. We then map those states onto a set of maximally-localized Wannier functions, and evaluate the matrix elements of the Hamiltonian and the other needed operators between the Wannier orbitals, thus setting up an ``exact tight-binding model.'' In this compact representation the k-space quantities are evaluated inexpensively using a generalized Slater-Koster interpolation. Because of the strong localization of the Wannier orbitals in real space, the smoothness and accuracy of the k-space interpolation increases rapidly with the number of grid points originally used to construct the Wannier functions. This allows k-space integrals to be performed with ab-initio accuracy at low cost. In the Wannier representation, band gradients, effective masses, and other k-derivatives needed for transport and optical coefficients can be evaluated analytically, producing numerically stable results even at band crossings and near weak avoided crossings.Comment: 12 pages, 7 figure

Personality Traits and Economic Preparation for Retirement

Working paper: WP2012-279This paper assesses the effects of personality traits on economic preparation for retirement, wealth accumulation, and consumption, among persons 66 to 69 years of age. Among the five chief personality traits of neuroticism, extroversion, agreeableness, conscientiousness, and openness, we focus most on conscientiousness. We find levels of adequate economic preparation for retirement ranging from 29 percent to 90 percent and that conscientiousness positively affects the proportion of persons adequately prepared for retirement, while neuroticism negatively affects it. Both consumption and wealth increase with conscientiousness but wealth increases faster, indicating that more conscientious persons save more out of retirement resources.Social Security Administrationhttp://deepblue.lib.umich.edu/bitstream/2027.42/97019/1/wp279.pd

Agricultural Land Use Planning and Groundwater Quality

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75123/1/j.1468-2257.1983.tb00394.x.pd

Dnmt3a regulates emotional behavior and spine plasticity in the nucleus accumbens.

Despite abundant expression of DNA methyltransferases (Dnmts) in brain, the regulation and behavioral role of DNA methylation remain poorly understood. We found that Dnmt3a expression was regulated in mouse nucleus accumbens (NAc) by chronic cocaine use and chronic social defeat stress. Moreover, NAc-specific manipulations that block DNA methylation potentiated cocaine reward and exerted antidepressant-like effects, whereas NAc-specific Dnmt3a overexpression attenuated cocaine reward and was pro-depressant. On a cellular level, we found that chronic cocaine use selectively increased thin dendritic spines on NAc neurons and that DNA methylation was both necessary and sufficient to mediate these effects. These data establish the importance of Dnmt3a in the NAc in regulating cellular and behavioral plasticity to emotional stimuli