Darwin's Other Books: “Red” and “Transmutation” Notebooks, “Sketch,” “Essay,” and Natural Selection

Study of Darwin's unpublished works, freely available on-line through the American Natural History Museum, reveals the origins of his thoughts on evolution

Challenges in Hyperon Decays

We give an personal overview of some of the unsolved problems related to hyperon decays. We cover nonleptonic decays, radiative decays and magnetic moments. Some of the theoretical issues are also touched upon.Comment: Contribution to Workshop On Low-Energy Pbar Storage Ring (Pbar2000

Gaussian process regression for virtual metrology of microchip quality and the resulting strategic sampling scheme

Manufacturing of integrated circuits involves many sequential processes, often ex- ecuted to nanoscale tolerances, and the yield depends on the often unmeasured quality of intermediate steps. In the high-throughput industry of fabricating microelectronics on semi-conducting wafers, scheduling measurements of product quality before the electrical test of the complete IC can be expensive. We therefore seek to predict metrics of product quality based on sensor readings describing the environment within the relevant tool during the processing of each wafer, or to apply the concept of virtual metrology (VM) to monitor these intermediate steps. We model the data using Gaussian process regression (GPR), adapted to simultaneously learn the nonlinear dynamics that govern the quality characteristic, as well as their operating space, expressed by a linear embedding of the sensor traces’ features. Such Bayesian models predict a distribution for the target metric, such as a critical dimension, so one may assess the model’s credibility through its predictive uncertainty. Assuming measurements of the quality characteristic of interest are budgeted, we seek to hasten convergence of the GPR model to a credible form through an active sampling scheme, whereby the predictive uncertainty informs which wafer’s quality to measure next. We evaluate this convergence when predicting and updating online, as if in a factory, using a large dataset for plasma-enhanced chemical vapor deposition (PECVD), with measured thicknesses for ~32,000 wafers. By approximately optimizing the information extracted from this seemingly repetitive data describing a tightly controlled process, GPR achieves ~10% greater accuracy on average than a baseline linear model based on partial least squares (PLS). In a derivative study, we seek to discern the degree of drift in the process over the several months the data spans. We express this drift by how unusual the relevant features, as embedded by the GPR model, appear as the in- puts compensate for degrading conditions. This method detects the onset of consistently unusual behavior that extends to a bimodal thickness fault, anticipating its flagging by as much as two days.Mechanical Engineerin

Intention-based economic theories of reciprocity

Recientemente, varios experimentos han mostrado que los individuos exhiben un comportamiento auténticamente recíproco en interacciones anónimas que se dan una sola vez ('one-shot'). En tanto que se ha mostrado que la reciprocidad es relevante en múltiples campos de la economía, han existido varios intentos por modelar el comportamiento recíproco. Este documento revisa los modelos de reciprocidad que se fundamentan en las intenciones y presenta un ejemplo para el caso del manejo de los profesores en el sector público, en el que el gobierno ofrece un esquema de incentivos para la implementación de un programa. Este esquema tiene la estructura del dilema del prisionero. Tanto en los juegos simultáneos como secuenciales, los resultados de equilibrio puede ser distintos a los que predice la teoría convencional. ************************************************************************ In recent years, several experiments have shown that individuals exhibit authentic reciprocal behavior in anonymous one-shot interactions. As reciprocity has been shown to be relevant in several economic fields, there have also been several attempts to model reciprocical behavior. I review the intention-based models of reciprocity and present an example in teachers´ management in the public sector in which a government offers an incentive scheme to implement a program. The incentive scheme has the prisioner’s dilemma structure, In both simultaneous and sequential games, in equilibrium reciprocal teachers may reach other equilibria different from those predicted by the standard theory.Game theory, psychological games,Intention-based models, reciprocl behaviour

Partial decentralization as a safeguard against favoritism

In this paper I investigate the optimal level of decentralization of tasks for theprovision of a local public good. I enrich the well-known trade-off between internalization of spillovers (that favors centralization) and accountability (that favors decentralization) by considering that public goods are produced through multiple tasks. This adds an additional institutional setting, partial decentralization, to the classical choice between full decentralization and full centralization. The main results are that partial decentralization is optimal when both the variance of exogenous shocks to electorate´s utility is large and the electorate expects high performance from politicians. I also show that the optimal institutional setting depends on the degree of substitutability/complementarity between tasks. In particular, I show that a large degree of substitutability between tasks makes favoritism more likely, which increases the desirability of partial decentralization as a safeguard against favoritism.Accountability, Multitask, Internalization of spillovers, Substitution.

Inelastic Model for Cyclic Biaxial Loading of Reinforced Concrete

National Science Foundation Research Grant GI 2993

On Exactly Solvable Potentials

We investigate two methods of obtaining exactly solvable potentials with analytic forms.Comment: 13 pages, Latex, to appear in Chineses Journal of Physic