Compression of Morbidity: In Retrospect and in Prospect

By postponing the age at which chronic infirmity begins,disability and morbidity could be compressed into a shorter period of the average human life span, resulting in a society in which the active and vital years of life would increase in length, the disabilities and frailties of ageing would be postponed,and the total amount of lifetime disability and morbidity would decrease

Higher-order surface FEM for incompressible Navier-Stokes flows on manifolds

Stationary and instationary Stokes and Navier-Stokes flows are considered on two-dimensional manifolds, i.e., on curved surfaces in three dimensions. The higher-order surface FEM is used for the approximation of the geometry, velocities, pressure, and Lagrange multiplier to enforce tangential velocities. Individual element orders are employed for these various fields. Stream-line upwind stabilization is employed for flows at high Reynolds numbers. Applications are presented which extend classical benchmark test cases from flat domains to general manifolds. Highly accurate solutions are obtained and higher-order convergence rates are confirmed.Comment: Submitted to International Journal for Numerical Methods in Fluids V1: Initial submission V2: Corrected errors in strong forms, revised discussion of the result

Hadronization of Dense Partonic Matter

The parton recombination model has turned out to be a valuable tool to describe hadronization in high energy heavy ion collisions. I review the model and revisit recent progress in our understanding of hadron correlations. I also discuss higher Fock states in the hadrons, possible violations of the elliptic flow scaling and recombination effects in more dilute systems.Comment: 8 pages, 4 figures; plenary talk delivered at SQM 2006, to appear in J. Phys.

Quark Recombination in Heavy Ion Collisions

Data on high energy nuclear collisions collected at the Relativistic Heavy Ion Collider over the past decade have provided convincing evidence that hadronization is quite different in hot nuclear environments compared to p+p collisions. In particular, the data suggest that we see traces of quark degrees of freedom in elliptic flow, with the implication that collective flow is generated on the parton level and is transfered to hadrons through a simple recombination step. In this contribution we review the experimental evidence for quark recombination and discuss some recombination models which are used to describe these effects.Comment: 12 pages, 5 figures; proceedings for the "Workshop on Critical Examination of RHIC Paradigms -- CERP 2010

The Foresight Bias in Monte-Carlo Pricing of Options with Early

In this paper we investigate the so called foresight bias that may appear in the Monte-Carlo pricing of Bermudan and compound options if the exercise criteria is calculated by the same Monte-Carlo simulation as the exercise values. The standard approach to remove the foresight bias is to use two independent Monte-Carlo simulations: One simulation is used to estimate the exercise criteria (as a function of some state variable), the other is used to calculate the exercise price based on this exercise criteria. We shall call this the numerical removal of the foresight bias. In this paper we give an exact definition of the foresight bias in closed form and show how to apply an analytical correction for the foresight bias. Our numerical results show that the analytical removal of the foresight bias gives similar results as the standard numerical removal of the foresight bias. The analytical correction allows for a simpler coding and faster pricing, compared to a numerical removal of the foresight bias. Our analysis may also be used as an indication of when to neglect the foresight bias removal altogether. While this is sometimes possible, neglecting foresight bias will break the possibility of parallelization of Monte-Carlo simulation and may be inadequate for Bermudan options with many exercise dates (for which the foresight bias may become a Bermudan option on the Monte-Carlo error) or for portfolios of Bermudan options (for which the foresight bias grows faster than the Monte-Carlo error). In addition to an analytical removal of the foresight bias we derive an analytical correction for the suboptimal exercise due to the uncertainty induced by the Monte-Carlo error. The combined correction for foresight bias (biased high) and suboptimal exercise (biased low) removed the systematic bias even for Monte-Carlo simulations with very small number of paths.Monte Carlo, Bermudan, Early Exercise, Regression, Least Square Approximation of Conditional Expectation, Least Square Monte Carlo, Longstaff-Schwartz, Perfect Foresight, Foresight Bias