Veterans\u27 Disability Benefits: Improvements Needed to Better Ensure VA Unemployability Decisions Are Well Supported

[Excerpt] In fiscal year 2013, over 330,000 of the approximately 3.7 million veterans VA compensated for disabilities incurred during active military service received TDIU benefits. The number of older veterans receiving TDIU benefits has been increasing, as has the total amount of benefit payments. From 2009 to 2013, the disability payments to those receiving TDIU benefits—the base payment plus the supplement—increased by 30 percent (to $11 billion in fiscal year 2013). For that year, we estimated$5.2 billion in payments for the supplement alone. These benefit trends have occurred alongside advances in medicine and technology and changes in the labor market and society. These trends have led to questions and suggested changes regarding TDIU benefits. My remarks today are based on our report issued on June 2, 2015, and like that report my statement (1) examines age-related trends in the population of Individual Unemployability beneficiaries and benefit payments; (2) assesses the procedures used for benefit decision-making; and (3) describes suggested options for revising the benefit

Efficient computation of hashes

The sequential computation of hashes at the core of many distributed storage systems and found, for example, in grid services can hinder efficiency in service quality and even pose security challenges that can only be addressed by the use of parallel hash tree modes. The main contributions of this paper are, first, the identification of several efficiency and security challenges posed by the use of sequential hash computation based on the Merkle-Damgard engine. In addition, alternatives for the parallel computation of hash trees are discussed, and a prototype for a new parallel implementation of the Keccak function, the SHA-3 winner, is introduced

Pappa Ante Portas: The effect of the husband's retirement on the wife's mental health in Japan

The \u201cRetired Husband Syndrome\u201d, that affects the mental health of wives of retired men around the world, has been anecdotally documented but never formally investigated. Using Japanese micro-data and the exogenous variation across cohorts in the maximum age of guaranteed employment induced by a 2006 Japanese reform, we estimate that the husband's earlier retirement significantly increases the probability that the wife reports symptoms related to the syndrome. We also find that retirement has a negative effect both on the household's economic situation and on the husband's own mental health, and that the higher economic distress contributes to reducing the wife's mental health

Phase lapses in scattering through multi-electron quantum dots: Mean-field and few-particle regimes

We show that the observed evolution of the transmission phase through multi-electron quantum dots with more than approximately ten electrons, which shows a universal (i.e., independent of N) as yet unexplained behavior, is consistent with an electrostatic model, where electron-electron interaction is described by a mean-field approach. Moreover, we perform exact calculations for an open 1D quantum dot and show that carrier correlations may give rise to a non-universal (i.e., N-dependent) behavior of the transmission phase, ensuing from Fano resonances, which is consistent with experiments with a few (N < 10) carriers. Our results suggest that in the universal regime the coherent transmission takes place through a single level while in the few-particle regime the correlated scattering state is determined by the number of bound particles.Comment: 14 pages, 3 figures, RevTex4 preprint format, to appear in Phys. Rev.

Effect of the Coulomb interaction on the electron relaxation of weakly-confined quantum dot systems

We study acoustic-phonon-induced relaxation of charge excitations in single and tunnel-coupled quantum dots containing few confined interacting electrons. The Full Configuration Interaction approach is used to account for the electron-electron repulsion. Electron-phonon interaction is accounted for through both deformation potential and piezoelectric field mechanisms. We show that electronic correlations generally reduce intradot and interdot transition rates with respect to corresponding single-electron transitions, but this effect is lessened by external magnetic fields. On the other hand, piezoelectric field scattering is found to become the dominant relaxation mechanism as the number of confined electrons increases. Previous proposals to strongly suppress electron-phonon coupling in properly designed single-electron quantum dots are shown to hold also in multi-electron devices. Our results indicate that few-electron orbital degrees of freedom are more stable than single-electron ones.Comment: 20 pages (preprint format), 7 figures, submitted to Phys. Rev.

Phonon-induced electron relaxation in weakly-confined single and coupled quantum dots

We investigate charge relaxation rates due to acoustic phonons in weakly-confined quantum dot systems, including both deformation potential and piezoelectric field interactions. Single-electron excited states lifetimes are calculated for single and coupled quantum dot structures, both in homonuclear and heteronuclear devices. Piezoelectric field scattering is shown to be the dominant relaxation mechanism in many experimentally relevant situations. On the other hand, we show that appropriate structure design allows to minimize separately deformation potential and piezolectric field interactions, and may bring electron lifetimes in the range of microseconds.Comment: 20 pages (preprint format), 7 figures, submitted to Physical Review

Landau levels, edge states and magneto-conductance in GaAs/AlGaAs core-shell nanowires

Magnetic states of the electron gas confined in modulation-doped core-shell nanowires are calculated for a transverse field of arbitrary strength and orientation. Magneto-conductance is predicted within the Landauer approach. The modeling takes fully into account the radial material modulation, the prismatic symmetry and the doping profile of realistic GaAs/AlGaAs devices within an envelope-function approach, and electron-electron interaction is included in a mean-field self-consistent approach. Calculations show that in the low free-carrier density regime, magnetic states can be described in terms of Landau levels and edge states, similar to planar two-dimensional electron gases in a Hall bar. However, at higher carrier density the dominating electron-electron interaction leads to a strongly inhomogeneous localization at the prismatic heterointerface. This gives rise to a complex band dispersion, with local minima at finite values of the longitudinal wave vector, and a region of negative magneto-resistance. The predicted marked anisotropy of the magneto-conductance with field direction is a direct probe of the inhomogeneous electron gas localization of the conductive channel induced by the prismatic geometry