54,966 research outputs found
Retirement Wealth Accumulation and Decumulation: New Developments and Outstanding Opportunities
Analysts have raised serious questions about current workers' ability and inclination to save enough for retirement. This is of obvious policy interest given the need to reform national retirement income programs. In the present paper we examine recent research developments regarding retirement wealth accumulation and decumulation. Our goal is to identify new developments and outstanding opportunities to encourage a more sensible process of growing and then drawing down retirement wealth.
Projected Retirement Wealth and Savings Adequacy in the Health and Retirement Study
Low saving rates raise questions about Americans' ability to maintain consumption levels in old age. Using the Health and Retirement Study, this paper explores asset holdings among a nationally representative sample of people on the verge of retirement. Making reasonable projections about asset growth, we assess how much more people would need to save in order to preserve consumption levels after retirement. We find that the median older household has current wealth of approximately 380,000 by retirement at age 62. Nevertheless, our model suggests that this median household will still need to save 16% of annual earnings to preserve pre-retirement consumption. For retirement at age 65, assets are expected to be about $420,000 and required additional saving totals 7% of earnings per year. These summary statistics conceal extraordinary heterogeneity in both assets and saving needs in the older population. Older high wealth households have 45 times more assets than the poorest decile and this disparity increases with age. There are also large differences in prescribed saving targets, ranging from 38% of annual earnings for those in the lowest wealth decile to negative rates for the wealthiest decile.
Comments on the nature of the outside boundary layer on a liquid sphere in a steady, uniform stream
Nature of outside boundary layer on liquid sphere in steady, uniform strea
Retirement Wealth Accumulation and Decumulation: New Developments and Outstanding Opportunities
Analysts have raised questions about current workers' ability and inclination to save" enough for retirement. This issue is of obvious policy interest given the current debate over" reforming national retirement income programs. This paper explores the implications of recent" research regarding retirement wealth accumulation and decumulation for this debate. Our goal is" to identify problems and opportunities in the area of preparedness for retirement."
External stress-corrosion cracking of a 1.22-m-diameter type 316 stainless steel air valve
An investigation was conducted to determine the cause of the failure of a massive AISI Type 316 stainless steel valve which controlled combustion air to a jet engine test facility. Several through-the-wall cracks were present near welded joints in the valve skirt. The valve had been in outdoor service for 18 years. Samples were taken in the cracked regions for metallographic and chemical analyses. Insulating material and sources of water mist in the vicinity of the failed valve were analyzed for chlorides. A scanning electron microscope was used to determine whether foreign elements were present in a crack. On the basis of the information generated, the failure was characterized as external stress-corrosion cracking. The cracking resulted from a combination of residual tensile stress from welding and the presence of aqueous chlorides. Recommended countermeasures are included
Mechanism for the failure of the Edwards hypothesis in the SK spin glass
The dynamics of the SK model at T=0 starting from random spin configurations
is considered. The metastable states reached by such dynamics are atypical of
such states as a whole, in that the probability density of site energies,
, is small at . Since virtually all metastable states
have a much larger , this behavior demonstrates a qualitative failure of
the Edwards hypothesis. We look for its origins by modelling the changes in the
site energies during the dynamics as a Markov process. We show how the small
arises from features of the Markov process that have a clear physical
basis in the spin-glass, and hence explain the failure of the Edwards
hypothesis.Comment: 5 pages, new title, modified text, additional reference
Density profiles and substructure of dark matter halos: converging results at ultra-high numerical resolution
Can N-body simulations reliably determine the structural properties of dark
matter halos? Focussing on a Virgo-sized galaxy cluster, we increase the
resolution of current ``high resolution simulations'' by almost an order of
magnitude to examine the convergence of the important physical quantities. We
have 4 million particles within the cluster and force resolution 0.5 kpc/h
(0.05% of the virial radius). The central density profile has a logarithmic
slope of -1.5, as found in lower resolution studies of the same halo,
indicating that the profile has converged to the ``physical'' limit down to
scales of a few kpc. Also the abundance of substructure is consistent with that
derived from lower resolution runs; on the scales explored, the mass and
circular velocity functions are close to power laws of exponents ~ -1.9 and -4.
Overmerging appears to be globally unimportant for suhalos with circular
velocities > 100 km/s. We can trace most of the cluster progenitors from z=3 to
the present; the central object (the dark matter analog of a cD galaxy)is
assembled between z=3 and 1 from the merging of a dozen halos with v_circ \sim
300 km/s. The mean circular velocity of the subhalos decreases by ~ 20% over 5
billion years, due to tidal mass loss. The velocity dispersions of halos and
dark matter globally agree within 10%, but the halos are spatially anti-biased,
and, in the very central region of the cluster, they show positive velocity
bias; however, this effect appears to depend on numerical resolution.Comment: 19 pages, 13 figures, ApJ, in press. Text significantly clarifie
Nondestructive testing techniques used in analysis of honeycomb structure bond strength
DOT /Driver-Displacement Oriented Transducer/, applicable to both lap shear type application and honeycomb sandwich structures, measures the displacement of the honeycomb composite face sheet. It incorporates an electromagnetic driver and a displacement measuring system into a single unit to provide noncontact bond strength measurements
Percolation Analysis of a Wiener Reconstruction of the IRAS 1.2 Jy Redshift Catalog
We present percolation analyses of Wiener Reconstructions of the IRAS 1.2 Jy
Redshift Survey. There are ten reconstructions of galaxy density fields in real
space spanning the range to , where
, is the present dimensionless density and
is the bias factor. Our method uses the growth of the largest cluster
statistic to characterize the topology of a density field, where Gaussian
randomized versions of the reconstructions are used as standards for analysis.
For the reconstruction volume of radius, Mpc,
percolation analysis reveals a slight `meatball' topology for the real space,
galaxy distribution of the IRAS survey.
cosmology-galaxies:clustering-methods:numericalComment: Revised version accepted for publication in The Astrophysical
Journal, January 10, 1997 issue, Vol.47
A System for Accessible Artificial Intelligence
While artificial intelligence (AI) has become widespread, many commercial AI
systems are not yet accessible to individual researchers nor the general public
due to the deep knowledge of the systems required to use them. We believe that
AI has matured to the point where it should be an accessible technology for
everyone. We present an ongoing project whose ultimate goal is to deliver an
open source, user-friendly AI system that is specialized for machine learning
analysis of complex data in the biomedical and health care domains. We discuss
how genetic programming can aid in this endeavor, and highlight specific
examples where genetic programming has automated machine learning analyses in
previous projects.Comment: 14 pages, 5 figures, submitted to Genetic Programming Theory and
Practice 2017 worksho
- âŠ