Survivor Funds

This Article explains how to create “survivor funds”—short-term investment funds that would pay more to those investors who live until the end of the fund’s term than to those who die before then. For example, instead of just investing in a ten-year bond and dividing the proceeds among the investors at the end of the bond term, a survivor fund would invest in that ten-year bond but divide the proceeds only among those who survived the full ten years. These survivor funds would be attractive investments because the survivors would get a greater return on their investments, while the decedents, for obvious reasons, would not care. Survivor funds would work like short-term tontines. Basically, a tontine is a financial product that combines features of an annuity and a lottery. In a simple tontine, a group of investors pools their money together to buy a portfolio of investments, and, as investors die, their shares are forfeited, often with the entire fund going to the last survivor. For example, imagine that ten 65-year-old men each contribute $1000 to a fund that buys a large diamond for$10,000 and that the men agree that the last “survivor will get the diamond. Accordingly, after the ninth man dies, the tenth man gets the diamond, and he can keep it or sell it. Of course, the survivor principle—that the share of each, at death, is enjoyed by the survivors—can be used to design financial products that would benefit multiple survivors, not just the last survivor. For example, elsewhere, we showed how tontines could be used to create so-called “tontine annuities” and “tontine pensions” that would benefit lots of retirees. In this Article, we show how the survivor principle can be used to create survivor funds that would only make payments to those who survive for a specified number of years

Temporal and spatial evolution of a waxing then waning catastrophic density current revealed by chemical mapping

We reconstruct the behavior of a catastrophic sustained radial pyroclastic density current as it waxed then waned during its brief lifespan. By subdividing the deposit into 8 time slices using a chemical tracer, we show that the sustained current initially was topographically restricted, but that its leading edge advanced in all directions, encroaching upon and gradually ascending hills. During peak flow the current reached its maximum extent and overtopped all topographic highs. After this, and while the current direction from source was maintained, the leading edge gradually retreated sourceward. High-resolution analysis of the depositional architecture reveals how the flow dynamics evolved and runout distance of the sustained density current rapidly increased then decreased, reflecting the dominant influence of changing mass flux, as demonstrated in numerical models but not previously distinguished in a natural deposit

The emittance of space radiator materials measured at elevated temperatures

The spectral emittances of textured space radiator materials between 1.7 and 14.7 micrometer have been evaluated at room temperature and elevated temperature (630 C) in air. Heating in air caused a permanent increase in spectral emittance for all materials tested: HCl/ion beam textured 304 stainless steel, untextured Ti (6 percent Al, 4 percent V), and sandblasted Ti (6 percent Al, 4 percent V). Changes in the surface chemistry and/or surface morphology of these materials were also observed. Elevated temperature spectral emittance was measured in an argon atmosphere and compared to the measurements in air. Similarity between the room temperature and elevated temperature spectral emittance measurements was also investigated, and limited agreement was found

Toma de decisiones compartidas en oncología apoyada en ayudas a la decisión al paciente en el screening y tratamiento del cáncer de próstata

Prostate cancer is an important problem among aging men in developed countries. Decisions about prostate cancer screening and treatment are characterized by multiple reasonable options and appear to be “close calls”, where the personal preferences of patients are important. Shared decisionmaking between patient and clinician is increasingly recognized as an ideal model for such “preference sensitive” choices involving screening, diagnosis, and therapy. Many randomized trials of decision aids for prostate cancer screening have consistently shown improvements in decision quality as well as lower interest in and uptake of PSA testing when patients are well informed. In contrast, more research is needed on the effect of decision aids on prostate cancer treatment decisions. However, given the evidence of effectiveness available at present, research is most urgently needed on how to routinely implement patient decision aids for PSA screening, as well as other fateful decisions including prostate cancer treatment, in clinical practice.El cáncer de próstata es un problema importante para los hombres mayores en países desarrollados. Las decisiones acerca del screening y tratamiento del cáncer de próstata se caracterizan por múltiples opciones razonables que parecen “arriesgadas”, donde las preferencias personales de los pacientes son importantes. Se va reconociendo de modo creciente la toma de decisión compartida entre el paciente y el clínico como un modelo ideal para elecciones “sensibles a las preferencias” tales como las implicadas en el screening, el diagnóstico, y el tratamiento. Muchos ensayos aleatorizados de ayudas a la decisión para el screening de cáncer de próstata han mostrado consistentemente mejorías en la calidad de la decisión, así como un mayor interés en llevar a cabo la prueba del PSA cuando los pacientes están bien informados. En contraste, es necesaria una mayor investigación sobre el efecto de las ayudas a la decisión en las decisiones sobre el tratamiento del cáncer de próstata. Sin embargo, con los datos disponibles sobre su efectividad, se hace muy necesaria la investigación sobre el modo de implantar las ayudas a la decisión en el cribado con PSA, así como en otras decisiones críticas que se dan en la práctica clínica durante el tratamiento del cáncer de próstata

Numerical analysis of pulse pedestal and dynamic chirp formation on picosecond modelocked laser pulses after propagation through a semiconductor optical amplifier

A numerical analysis, based on a modified Schrodinger equation, of the formation of pulse pedestals and dynamic chirp formation on picosecond pulses after propagation through a semiconductor optical amplifier is presented. The numerical predictions are confirmed by an experiment that utilises the frequency resolved optical gating technique for the amplified pulse characterisation

Numerical analysis of four-wave mixing between 2 ps mode-locked laser pulses in a tensile-strained bulk SOA

A numerical model of four-wave mixing between 2-ps pulses in a tensile-strained bulk semiconductor optical amplifier is presented. The model utilizes a modified Schrodinger equation to model the pulse propagation. The Schrodinger equation parameters such as the material gain first and second order dispersion, linewidth enhancement factors and optical loss coefficient are obtained using a previously developed steady-state model. The predicted four-wave mixing pulse characteristics show reasonably good agreement with experimental pulse characteristics obtained using frequency resolved optical gating