Copolyamides of nylon-4,6 and nylon-4,T

Copolyamides of nylon-4,6 and nylon-4,T were prepared by a two-step method: (1) a prepolymerization in an autoclave (40 min at 210°C) and (2) a postcondensation in the solid state (4 h, 260°C). On these materials was studied the melting behavior with DSC, the crystalline structure with WAXS, the water absorption, and the mechanical properties with a torsion pendulum. In these copolyamides the order was found to remain high, but the crystalline structures of -4,6 and -4,T were not isomorphous. The torsion moduli increased with -4,T content both at RT and at 140°C

The victory of hope over Angst? : Funding, asset allocation, and risk-taking in german public sector pension reform

Public employee pension systems throughout the developed world have traditionally been of the pay-as-you-go (PAYGO) defined benefit (DB) variety, where pensioner payments are financed by taxes (contributions) levied on the working generation. But as the number of retirees rises relative to the working-age group, such systems have begun to face financial distress. This trend has been exacerbated in many countries, among them Germany, by high unemployment rates producing further deterioration of the contribution base. In the long run, public sector pension benefits will have to be cut or contributions increased, if the systems are to be maintained. An alternative path sometimes offered to ease the crunch of paying for public employee pensions is to move toward funding: here, plan assets are gradually built up, invested, and enhanced returns devoted to partly defray civil servants’ pension costs. In this study, we evaluate the impact of introducing partial prefunding, paired with a strategic investment policy for the German federal state of Hesse. The analysis assesses the impact of introducing a supplementary tax-sponsored pension fund whose contributions are invested in the capital market and used to relieve the state budget from (some) pension payments. Our model determines the expectation and the Conditional Value-at-Risk of economic pension costs using a stochastic simulation process for pension plan assets. This approach simultaneously determines the optimal contribution rate and asset allocation that controls the expected economic costs of providing the promised pensions, while at the same time controlling investment risk. Specifically, we offer answers to the following questions: 1. How can the plan be designed to control cash-flow shortfall risk, so as to mitigate the potential burden borne by future generations of taxpayers? 2. What is the optimal asset allocation for this fund as it is built up, to generate a maximum return while simultaneously restricting capital market and liability risk? 3. What are reasonable combinations of annual contribution rates and asset allocation to a state-managed pension fund, which will limit costs of providing promised public sector pensions? We anticipate that this research will interest several sorts of policymaker groups. First, focusing on the German case, the state and Federal governments should find it relevant, as these entities face considerable public sector pension liabilities. Second, our findings will also be of interest to other European countries, as most have substantial underfunded defined benefit plans for civil servants. In what follows, we first offer a brief description of the structure of civil servant pensions in Germany, focusing on their benefit formulas, their financing, and the resulting current as well as future plan obligations for taxpayers. Next, we turn to an analysis of the actuarial status of the Hesse civil servants’ pension plan and evaluate how much would have to be contributed to fund this plan in a nonstochastic context. Subsequently we evaluate the asset-liability and decision-making process from the viewpoint of the plan sponsor, to determine sensible plan asset allocation behavior. A final section summarizes findings and implications.Wie in vielen anderen Ländern auch, beruhen die deutschen Beamtenpensionen traditionell auf einem umlage- und steuerfinanzierten System der Leistungszusage (defined benefit pension – DB). Aufgrund fehlender Rücklagen resultieren aus den Pensionsverspechen ungedeckte Verbindlichkeiten in Milliardenhöhe, die als solche jedoch nicht offiziell als Staatsverschuldung ausgewiesen werden. Das damit einhergehende Problem steigender Belastungen zukünftiger Haushalte wurde von der Politik erkannt, und erste Schritte in Richtung Kapitaldeckung wurden mit der Einführung der Versorgungsrücklagen sowie der Finanzierungsfonds vollzogen. Vor diesem Hintergrund evaluiert diese Studie die Chancen und Risiken, die mit dem Übergang zu einem (partiell) kapitalgedeckten Beamtenpensionssystems verbunden sind. Als Datengrundlage dient hierzu die vollständige Personalstandsstatistik des Landes Hessen, dessen Beamtenpopulation repräsentativ für den größten Teil des deutschen Beamtensystems ist. Unter Verwendung eigens für diese Studie berechneter Beamtensterbetafeln werden zunächst die Pensionsansprüche der aktuellen Pensionäre sowie die bereits erdienten Anwartschaften der aktuell diensttuenden Beamten aktuariell bewertet. Auf Grundlage einer 50-Jahres-Prognose der Beamtenpopulationsentwicklung werden die zur Finanzierung der Pensionsversprechen benötigten Beiträge, d.h. der Beitragssatz in Bezug auf die Beamtengehälter, deterministisch bestimmt. Im Rahmen einer Monte Carlo-Studie und auf Basis eines stochastischen Barwert-Ansatzes wird sodann die Anlagestrategie für das Planvermögen bestimmt, die zu minimalem Crash-Risiko, gemessen als Conditional Value at Risk der gesamten Pensionskosten, führt. Abschließend wird aufgezeigt, welchen Freiraum der Pensionsplanmanager hinsichtlich der Wahl von Beitragssatz und Anlagestrategie hat, wenn er nur auf Einhaltung eines vorgegebenen Risikobudgets verpflichtet wurde

A chain rule for the expected suprema of Gaussian processes

The expected supremum of a Gaussian process indexed by the image of an index set under a function class is bounded in terms of separate properties of the index set and the function class. The bound is relevant to the estimation of nonlinear transformations or the analysis of learning algorithms whenever hypotheses are chosen from composite classes, as is the case for multi-layer models

Time is money: life cycle rational inertia and delegation of investment management : [Version November 2013]

We investigate the theoretical impact of including two empirically-grounded insights in a dynamic life cycle portfolio choice model. The first is to recognize that, when managing their own financial wealth, investors incur opportunity costs in terms of current and future human capital accumulation, particularly if human capital is acquired via learning by doing. The second is that we incorporate age-varying efficiency patterns in financial decisionmaking. Both enhancements produce inactivity in portfolio adjustment patterns consistent with empirical evidence. We also analyze individuals’ optimal choice between self-managing their wealth versus delegating the task to a financial advisor. Delegation proves most valuable to the young and the old. Our calibrated model quantifies welfare gains from including investment time and money costs, as well as delegation, in a life cycle setting

Betting on Death and Capital Markets in Retirement: A Shortfall Risk Analysis of Life Annuities versus Phased Withdrawal Plans

How might retirees consider deploying the retirement assets accumulated in a defined contribution pension plan? One possibility would be to purchase an immediate annuity. Another approach, called the “phased withdrawal” strategy in the literature, would have the retiree invest his funds and then withdraw some portion of the account annually. Using this second tactic, the withdrawal rate might be determined according to a fixed benefit level payable until the retiree dies or the funds run out, or it could be set using a variable formula, where the retiree withdraws funds according to a rule linked to life expectancy. Using a range of data consistent with the German experience, we evaluate several alternative designs for phased withdrawal strategies, allowing for endogenous asset allocation patterns, and also allowing the worker to make decisions both about when to retire and when to switch to an annuity. We show that one particular phased withdrawal rule is appealing since it offers relatively low expected shortfall risk, good expected payouts for the retiree during his life, and some bequest potential for the heirs. We also find that unisex mortality tables if used for annuity pricing can make women’s expected shortfalls higher, expected benefits higher, and bequests lower under a phased withdrawal program. Finally, we show that delayed annuitization can be appealing since it provides higher expected benefits with lower expected shortfalls, at the cost of somewhat lower anticipated bequests.

Vortex pinning by cylindrical defects in type-II superconductors: Numerical solutions to the Ginzburg-Landau equations

We numerically integrate the one-dimensional, cylindrically symmetric Ginzburg-Landau equations to calculate the spatial variation of the order parameter and supercurrents for a vortex trapped by a cylindrical defect. We use the resulting field distributions to estimate the pinning energy, and make use of the vortex/two-dimensional boson analogy to calculate the depinning temperature. The microscopic behavior oi the fields depends on the size, and the conductivity of the cylindrical defect appears to be important for the pinning

Deregulation : an update

Cover titleOctober 1981Includes bibliographical reference