Analysis Of The Sustainability Of Endowment Fund Spending Rates From Domestic And Internationally Diversified Portfolios

Portfolio success rates do not diminish greatly when spending is increased from 5% to 7% in equity-heavy portfolios. Foreign equities increase the sustainability of spending rates in shorter planning periods. Portfolio success rate analyses were completed for hypothetical endowment portfolios of S&P 500 stocks, MSCIs Developed World x USA Index, and high-grade corporate bonds for planning periods of 1, 5, 10, and 15 years using overlapping samples of quarterly returns from the first quarter of 1970 through the fourth quarter of 2003. A portfolio is considered a success if at the end of the planning period the portfolios nominal value in Table 1 or deflated value in Table 2 net of spending is equal to or greater than its value at the beginning of the planning period. Higher portfolio success rates suggest greater sustainability of spending rates

Sustainability Of Substantially Equal Periodic Payments In Early Retirement Under Section 72(t)

Early distributions from tax-deferred retirement plans are allowed without penalty but must continue under for the longer of five years or until the retiree’s age 59½.  Early distributions under IRS Section 72(t) potentially have life altering consequences and thus require analysis of sustainability distributions through the 72(t) period

What Has Happened To International Diversification? Returns, Risks, And Correlations

Factors other than correlation must be considered in order to understand the reduced diversification effects of EAFE stocks in U. S. portfolio. The diminished importance of EAFE stocks as diversifying securities can be traced first to higher risk in comparison to the S&P 500 and corporate bonds. A comparison of returns to EAFE in the 1990s versus U. S. securities further demonstrates the lack of competitiveness of EAFE stocks for funds in optimized portfolios. Nevertheless, long-term average returns, risks, and correlations provide evidence in support of international diversification of U. S. portfolios

Portfolio Diversification With NAFTA Equities

The results of our analysis suggests that diversified investment in the Mexican stock market has provided significant diversification and returns enhancement benefits to U. S. investors and that Canadian stocks offer only occasional return/risk improvement over a U.S. equities portfolio.  When correlations among the three markets are considered, we see diversification opportunities in the longer periods of returns but also increasing convergence of the Mexican and Canadian markets with the U.S. stock market in recent years.  The implications of our findings are that, if 17 years of returns data are representative of future expectations, there are clear return/risk enhancing advantages to including Mexican stocks in U.S. portfolio

Precious Metals And Retirement Portfolio Survival Rates

Recent gains in the value of gold bullion in the presence of declines in the stock and corporate bond markets suggest that retired investors may benefit from holdings of precious metals.  Because of the comparative liquidity and economy of holding mutual fund shares, we examine the effect of an optimal allocation of precious metals funds shares on portfolio survival rates through payout periods of 15, 20, 25, 30, and 35 years using returns data from September 1988 through December 2008.  Since most of the higher withdrawal rates that are supported by precious metals funds are ill-advised, adding precious metals fund shares to a conventional stocks and bonds portfolio does not appear to benefit most retired investors.  The findings do support greater allocations to bonds rather than stocks

In-roads to the spread of antibiotic resistance: regional patterns of microbial transmission in northern coastal Ecuador

The evolution of antibiotic resistance (AR) increases treatment cost and probability of failure, threatening human health worldwide. The relative importance of individual antibiotic use, environmental transmission and rates of introduction of resistant bacteria in explaining community AR patterns is poorly understood. Evaluating their relative importance requires studying a region where they vary. The construction of a new road in a previously roadless area of northern coastal Ecuador provides a valuable natural experiment to study how changes in the social and natural environment affect the epidemiology of resistant Escherichia coli. We conducted seven bi-annual 15 day surveys of AR between 2003 and 2008 in 21 villages. Resistance to both ampicillin and sulphamethoxazole was the most frequently observed profile, based on antibiogram tests of seven antibiotics from 2210 samples. The prevalence of enteric bacteria with this resistance pair in the less remote communities was 80 per cent higher than in more remote communities (OR = 1.8 [1.3, 2.3]). This pattern could not be explained with data on individual antibiotic use. We used a transmission model to help explain this observed discrepancy. The model analysis suggests that both transmission and the rate of introduction of resistant bacteria into communities may contribute to the observed regional scale AR patterns, and that village-level antibiotic use rate determines which of these two factors predominate. While usually conceived as a main effect on individual risk, antibiotic use rate is revealed in this analysis as an effect modifier with regard to community-level risk of resistance

Predicting protein-protein interface residues using local surface structural similarity

<p>Abstract</p> <p>Background</p> <p>Identification of the residues in protein-protein interaction sites has a significant impact in problems such as drug discovery. Motivated by the observation that the set of interface residues of a protein tend to be conserved even among remote structural homologs, we introduce <it>PrISE</it>, a family of local structural similarity-based computational methods for predicting protein-protein interface residues.</p> <p>Results</p> <p>We present a novel representation of the surface residues of a protein in the form of structural elements. Each structural element consists of a central residue and its surface neighbors. The <it>PrISE </it>family of interface prediction methods uses a representation of structural elements that captures the atomic composition and accessible surface area of the residues that make up each structural element. Each of the members of the <it>PrISE </it>methods identifies for each structural element in the query protein, a collection of <it>similar </it>structural elements in its repository of structural elements and weights them according to their similarity with the structural element of the query protein. <it>PrISE_L</it>relies on the similarity between structural elements (i.e. local structural similarity). <it>PrISE_G</it>relies on the similarity between protein surfaces (i.e. general structural similarity). <it>PrISE_C</it>, combines local structural similarity and general structural similarity to predict interface residues. These predictors label the central residue of a structural element in a query protein as an interface residue if a weighted majority of the structural elements that are similar to it are interface residues, and as a non-interface residue otherwise. The results of our experiments using three representative benchmark datasets show that the <it>PrISE_C</it>outperforms <it>PrISE_L</it>and <it>PrISE_G</it>; and that <it>PrISE_C</it>is highly competitive with state-of-the-art structure-based methods for predicting protein-protein interface residues. Our comparison of <it>PrISE_C</it>with <it>PredUs</it>, a recently developed method for predicting interface residues of a query protein based on the known interface residues of its (global) structural homologs, shows that performance superior or comparable to that of <it>PredUs </it>can be obtained using only local surface structural similarity. <it>PrISE_C</it>is available as a Web server at <url>http://prise.cs.iastate.edu/</url></p> <p>Conclusions</p> <p>Local surface structural similarity based methods offer a simple, efficient, and effective approach to predict protein-protein interface residues.</p

Author Correction: Nuclear-mitochondrial DNA segments resemble paternally inherited mitochondrial DNA in humans

An amendment to this paper has been published and can be accessed via a link at the top of the paper