Optimal life cycle asset allocation : understanding the empirical evidence.

We show that a life-cycle model with realistically calibrated uninsurable labor income risk and moderate risk aversion can simultaneously match stock market participation rates and asset allocation decisions conditional on participation. The key ingredients of the model are Epstein–Zin preferences, a fixed stock market entry cost, and moderate heterogeneity in risk aversion. Households with low risk aversion smooth earnings shocks with a small buffer stock of assets, and consequently most of them (optimally) never invest in equities. Therefore, the marginal stockholders are (endogenously) more risk averse, and as a result they do not invest their portfolios fully in stocks.

Portfolio choice with internal habit formation : a life-cycle model with uninsurable labor income risk.

Motivated by the success of internal habit formation preferences in explaining asset pricing puzzles, we introduce these preferences in a life-cycle model of consumption and portfolio choice with liquidity constraints, undiversifiable labor income risk and stock-market participation costs. In contrast to the initial motivation, we find that the model is not able to simultaneously match two very important stylized facts: a low stock market participation rate, and moderate equity holdings for those households that do invest in stocks. Habit formation increases wealth accumulation because the intertemporal consumption smoothing motive is stronger. As a result, households start participating in the stock market very early in life, and invest their portfolios almost fully in stocks. Therefore, we conclude that, with respect to its ability to match the empirical evidence on asset allocation behavior, the internal habit formation model is dominated by its time-separable utility counterpart.

The Excess Burden of Government Indecision

Governments are known for procrastinating when it comes to resolving painful policy problems. Whatever the political motives for waiting to decide, procrastination distorts economic decisions relative to what would arise with early policy resolution. In so doing, it engenders excess burden. This paper posits, calibrates, and simulates a life cycle model with earnings, lifespan, investment return, and future policy uncertainty. It then measures the excess burden from delayed resolution of policy uncertainty. The first uncertain policy we consider concerns the level of future Social Security benefits. Specifically, we examine how an agent would respond to learning in advance whether she will experience a major Social Security benefit cut starting at age 65. We show that having to wait to learn materially affects consumption, saving, and portfolio decisions. It also reduces welfare. Indeed, we show that the excess burden of government indecision can, in this instance, range as high as 0.6 percent of the agent's economic resources. This is a significant distortion in of itself. It's also significant when compared to other distortions measured in the literature. The second uncertain policy we consider concerns marginal tax rates. We obtain similar results once we adjust for the impact of tax rates on income.

Dealing with the nucleus during cell migration

© 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).The position of the nucleus within cells is a key event during cell migration. The movement and positioning of the nucleus strongly impacts cell migration. Notably, the last two years largely contributed to emphasise the dynamicity of the nucleus-cytoskeleton interactions that occur during cell migration. Nuclei are under continuous tension from opposing intracellular forces and its tether to the cytoskeleton can be regulated at different levels. Interestingly, it was showed how nuclear positioning is highly related to cell function. In most migrating cells, including cancer cells, the nucleus can be the rate limiting step of cell migration and is placed away from the leading edge. By contrast, leukocytes position their nucleus close to the lamellipodia at the leading edge, and the nucleus contributes to drilling through the endothelium. Differences in cell migration in 2D versus 3D environments are also evident. The mechanisms and forces at play during nuclear positioning and translocation are clearly affected by the nature of the substrate. As such nuclear positioning during cell migration can vary between cell types and environments. In this review we aim to give an overview of the latest discoveries in the field revealing how nuclear positioning is tightly regulated, not only by intrinsic nuclear properties, such as deformability, nuclear envelope content or nucleus-cytoskeleton connectivity, but also by the microenvironment.This work was supported by the European Research Council, EMBO installation, LISBOA-01-0145-FEDER-007391, project cofunded by FEDER, through POR Lisboa 2020 — Programa Operacional Regional de Lisboa, Portugal 2020 and Fundação para a Ciência e a Tecnologia.info:eu-repo/semantics/publishedVersio

Levantamento arqueológico do Algarve: concelho de Lagoa

O Concelho de Lagoa, apesar da sua apreciável riqueza arqueológica, onde se destaca a estação pré-histórica de Caramujeira, descoberta em 1974 e cujos menires são hoje conhecidos do mundo científico, não se têm nele processado trabalhos de investigação que o valorizem. São excepção as pequenas escavações realizados no Ilhéu do Rosário, em meados do passado século e sob orientação de Estácio da Veiga, em Ferragudo e na Gruta de lbn Amar (Mexilhoeira), ainda quase inéditas, apesar de terem sobre elas decorrido mais de vinte e cinco anos, ou as breves campanhas verificadas na Caramujeira. De facto, os conhecimentos disponíveis sobre o seu património arqueológico resultam, sobretudo, de alguns achados ocasionais, das prospecções de Estácio da Veiga , das que um de nós procedeu nos anos setenta (M.V.G.), e das agora efectuadas e a que se somaram muitas informações dispersas, tendo em vista a elaboração do presente estudo.info:eu-repo/semantics/publishedVersio

The dynamic analysis of piping systems using pseudo-dynamic techniques

This paper describes an application of pseudo-dynamic techniques to the dynamic analysis of piping structures. Essentially it consists in coupling a direct time integration algorithm, such as the Newmark method, to an experimental step. At each time step the integration algorithm generates a displacement vector of the structure, which is prescribed for the test specimen. This is mounted in a rigid test rig fitted with a set of displacement actuators and load cells at the level of the structure degrees of freedom. The load cells allow the reading of the internal restoring force vector, which is fed back to the direct time integration algorithm in an actual time step. Further calculations for the velocity and acceleration vectors will define a new structure configuration by evaluating a new displacement vector referred to the next time step. This procedure makes it possible to assess experimentally a realistic stress distribution at sections of complex shape piping parts. The method is a precise tool in dynamic analysis and, on being carried out in a quasi-static procedure, it operates with less expensive equipment than is necessary in real dynamic test

Investing Retirement Wealth: A Life-Cycle Model

If household portfolios are constrained by borrowing and short-sales restrictions asset markets, then alternative retirement savings systems may affect household welfare by relaxing these constraints. This paper uses a calibrated partial-equilibrium model of optimal life-cycle portfolio choice to explore the empirical relevance of these issues. In a benchmark case, we find ex-ante welfare gains equivalent to a 3.7% increase in consumption from the investment of half of retirement wealth in the equity market. The main channel through which these gains are realized is that the higher average return on equities permits a lower Social Security tax rate on younger households, which helps households smooth their consumption over the life cycle. There is a smaller welfare gain of 0.5% of consumption when Social Security tax rates are held constant. We also find that realistic heterogeneity of risk aversion and labor income risk can strongly affect optimal portfolio choice over the life cycle, which provides one argument for a privatized Social Security system with an element of personal portfolio choice.

Stock Market Mean Reversion and the Optimal Equity Allocation of a Long-Lived Investor

This paper solves numerically the intertemporal consumption and portfolio choice problem of an infinitely-lived investor who faces a time-varying equity premium. The solutions we obtain are very similar to the approximate analytical solutions of Campbell and Viceira (1999), except at the upper extreme of the state space where both the numerical consumption and portfolio rules flatten out. We also consider a constrained version of the problem in which the investor faces borrowing and short-sales restrictions. These constraints bind when the equity premium moves away from its mean in either direction, and are particularly severe for risk-tolerant investors. The constraints have substantial effects on optimal consumption, but much more modest effects on optimal portfolio choice in the region of the state space where they are not binding.Economic

Evaluation of the biocompatibility of root canal sealers using subcutaneous implants

The purpose of this study was to evaluate in vivo the biocompatibility of Endométhasone, Pulp Canal Sealer EWT and AH-Plus root canal sealers after implantation in rat connective tissue. Twenty-four Wistar-Furth rats were used. Polyethylene tubes were filled with the sealers and implanted into specific dorsal subdermal tissue sites of the rats. Implants were removed after 3, 7 and 30 days, fixed and processed for glycol methacrylate-embedding technique to be examined microscopically. On the 3rd day, there was a mild inflammatory reaction to Pulp Canal Sealer EWT implants, but a severe response to the other sealers with presence of acute inflammatory cells. On the 7th day, tissue organization was more evident with attenuation of the inflammatory reaction, especially for the AH-Plus implants. On the 30th day, connective tissue with few inflammatory cells was observed in contact with all sealer implants. In this time interval, the tissue in contact with Pulp Canal Sealer EWT implants was more organized, while the tissue close to Endométhasone and AH-Plus implants showed a mild persistent inflammatory reaction and had similar results to each other. In conclusion, the sealers had a similar pattern of irritation, which was more severe in the beginning and milder with time, in such a way that all sealers showed a persistent mild reaction. Pulp Canal Sealer EWT yielded better tissue organization than Endométhasone and AH-Plus, which, in turn, showed similar results to each other