A lattice of Magneto-Optical and Magnetic traps for cold atoms

We describe basic periodic trapping configurations for ultracold atoms above surfaces. The approach is based on a simple wire grid and can be scaled to provide large arrays of periodically arranged magnetic or magneto-optical traps. The unit cells of the trap lattices are based on crossed wire segments. By alternating the current directions in the wires of the grid it can be distinguished between 3 basic lattice configurations. As a first demonstration, we used macroscopic wires in a 2 layer configuration to realize the unit cells of the lattices. With this experimental setup, we observe two of the basic unit cells and an array of 2x2 magneto optical traps.Comment: 8 pages, including 8 figure

CTK - A new CCD Camera at the University Observatory Jena

The Cassegrain-Teleskop-Kamera (CTK) is a new CCD imager which is operated at the University Observatory Jena since begin of 2006. This article describes the main characteristics of the new camera. The properties of the CCD detector, the CTK image quality, as well as its detection limits for all filters are presented.Comment: AN accepted, 6 pages, 15 figures, 2 table

Withdrawal Rates, Savings Rates, and Valuation-Based Asset Allocation

While most everyone would agree that valuations matter, the question remains as to whether clients with a long-term outlook (such as those planning for retirement) can hope to act successfully on information about valuations. This article provides favorable evidence based on the historical record for long-term conservative investors to obtain improved retirement planning outcomes (lower savings rates, higher withdrawal rates) using valuation-based asset allocation strategies. This is illustrated with a specific example comparing a 50/50 fixed allocation strategy to a Graham and Dodd inspired valuation-based strategy with a stock allocation of 25, 50, or 75% determined by the value of the cyclically-adjusted price-earnings ratio with respect to its median value up to that point in history. Important caveats are discussed. But even if clients or advisors decide against adopting valuation-based asset allocation, advisors may at least be able to use the findings of this research to help persuade clients to stay the course and not give in to the temptation to change their asset allocations in the “wrong direction,” such as increasing stock holdings after valuations rise or panicking and selling stocks after a plummet in valuations.market valuations; cyclically-adjusted price-earnings ratio; PE10; stock returns; asset allocation; retirement planning

Can We Predict the Sustainable Withdrawal Rate for New Retirees?

I investigate how well market valuation and yield measures predict the maximum sustainable withdrawal rate (MWR) that a person can use with their retirement savings to obtain inflation-adjusted income over a 30-year period. The regression framework includes variables to predict long-term stock returns, bond returns, and inflation (the components driving a retiree's remaining portfolio balance). It produces estimates that fit the historical data well. This study suggests that a 4 percent withdrawal rate cannot be considered as safe for U.S. retirees in recent years when the cyclically-adjusted price-earnings ratio has experienced historical highs and the dividend yield has experienced historical lows. Nevertheless, there are important qualifications for these predictions. Most importantly, they depend on out-of-sample estimates as the circumstances of the past 15 years have not been witnessed before. Readers persuaded by this analysis may wish to include TIPS and other assets as a part of their portfolios, and recent retirees should closely monitor their spending and portfolio balance. Maintaining flexibility with retirement spending is important. More generally, this framework can guide new retirees toward a reasonable range for their expected MWR so that the 4 percent rule need not be blindly followed.safe withdrawal rates, retirement planning, market valuation, price-earnings ratio, dividend yield, stock returns, bond returns

Emerging Market Pension Funds and International Diversification

Many countries are currently increasing the advanced funding of their public pension systems to improve their sustainability in the face of rapidly aging populations. When pensions are funded, the issue of asset allocation becomes of paramount importance. Standard portfolio selection theory provides a fundamental justification for international diversification: by widening the pool of potential assets, investors can potentially increase returns while possibly even reducing risks through the selection of complementary assets with low correlations. Nonetheless, many emerging market countries have regulations that strictly limit the choice of investments for pension funds, in some cases excluding international assets entirely. This paper uses modern portfolio theory to determine the optimal asset allocation for public pension systems in emerging market countries. We find that on average, about half of the portfolios of emerging market countries should be in world assets. The paper then quantifies the costs of prohibiting international diversification.emerging markets; asset allocation; pensions; defined-contribution

Getting on Track for a Sustainable Retirement: A Reality Check on Savings and Work

The aim of traditional retirement planning is to set a wealth accumulation target for your retirement date so that your desired expenditures can be obtained using a “safe” withdrawal rate. But it is quite difficult to know if you are making progress toward this target. Volatility over short periods of time strongly limits the usefulness of using your current wealth accumulation at ten or even five years before retirement to predict your final retirement wealth. Fortunately, it is not necessary to focus on a retirement wealth accumulation target. The accumulation and retirement phases should not be treated separately in this way. This paper outlines a framework for considering if someone in mid-career is on track for a sustainable retirement. It investigates what combinations of savings rates and years of continued work would have allowed someone to have always accumulated enough by retirement to afford one’s desired retirement expenditures in all of the rolling periods from the historical data. A strategy is “safe” if it worked in the worst-case offered thus far by history. I consider a 55 year old as a case study to show what savings rate will be needed to retire 10 years later, or how much longer one should work with a variety of other savings rates. Results are shown for a wide variety of situations. These findings can potentially serve as a reality check about the sustainability of one’s retirement plans.retirement planning; lifetime perspective; safe savings rate; safe retirement age; wealth accumulation targets; retirement spending goals; safe withdrawal rates

Comparing the Impacts of Social Security Benefit Reductions on the Income Distribution of the Elderly

Benefit reductions will likely be a part of the eventual Social Security reform in the United States. This research attempts to quantify the intragenerational and intergenerational impacts of different benefit reduction proposals on the incomes of the elderly. Reforms include across-the-board benefit cuts, price indexing, and reductions to the cost-of-living adjustment. Restoring the projected seventy-five year balance for the Trust Fund through benefit reductions will significantly lower benefits, though the impacts vary by type of reform. Nonetheless, the savings for the Social Security Trust Fund will exceed the accompanying increases in the poverty gap, leaving room to provide minimal income guarantees.Social Security; price indexing; cost-of-living adjustment; poverty; benefit reductions

Nearly optimal asset allocations in retirement

An important and frequently studied question for retirees is: what is the optimal asset allocation during retirement? This article provides a brief but simple message that conservative asset allocations in retirement are quite acceptable after all. A wide range of asset allocations tend to provide very similar results in terms of sustainable withdrawal rates for given probabilities of failure. For example, with Monte Carlo simulations based on historical data parameters, a 4.4 percent withdrawal rate for a 30-year horizon could be supported with a 10 percent chance of failure using a 50/50 asset allocation of stocks and bonds. But the range of stock allocations supporting a withdrawal rate within 0.1 percentage points of this maximum extend from 27 to 87 percent. Though asset allocation will also impact the amount which can be left as bequests, it is the case that relatively low stock allocations can support retirees just as well for a given failure rate and retirement duration.retirement planning; safe withdrawal rates; asset allocation

Predicting Sustainable Retirement Withdrawal Rates Using Valuation and Yield Measures

This study attempts to quantify whether a 4 percent withdrawal rate can still be considered as safe for U.S. retirees in recent years when earnings valuations have been at historical highs and the dividend yield has been at historical lows. We find that the traditional 4 percent withdrawal rule is likely to fail for recent retirees. The maximum sustainable withdrawal rate (MWR) for retirees may continue declining even after the peak in earnings valuations in 2000. Our lowest point estimate for an MWR with a 60/40 allocation between stocks and bonds is 1.46 percent for new retirees in 2008. We also discuss confidence intervals for these predictions. The regression framework with variables to predict long-term stock returns, bond returns, and inflation (the components driving the retiree's remaining portfolio balance) produces estimates that fit the historical data quite well, and we use backtesting for a further robustness check. Nevertheless, there are important qualifications for these predictions. In particular, they depend on out-of-sample estimates as the circumstances of the past 15 years have not been witnessed before, and there is always potential for structural changes which could leave recent retirees in better shape than suggested by the model. Looking forward, this methodology can guide new retirees toward a reasonable range for their MWR so that the 4 percent rule need not be blindly followed.safe withdrawal rates, retirement planning, market valuation, price-earnings ratio, dividend yield. stock returns, bond returns