Changes in cerebral arterial pulsatility and hippocampal volume: a transcranial doppler ultrasonography study.

The physiological mechanisms of age-related cognitive decline remain unclear, in no small part due to the lack of longitudinal studies. Extant longitudinal studies focused on gross neuroanatomy and diffusion properties of the brain. We present herein a longitudinal analysis of changes in arterial pulsatility - a proxy for arterial stiffness - in two major cerebral arteries, middle cerebral and vertebral. We found that pulsatility increased in some participants over a relatively short period and these increases were associated with hippocampal shrinkage. Higher baseline pulsatility was associated with lower scores on a test of fluid intelligence at follow-up. This is the first longitudinal evidence of an association between increase in cerebral arterial stiffness over time and regional shrinkage.

Evolution of fairness in the dictator game by multilevel selection.

The most perplexing experimental results on fairness come from the dictator game where one of two players, the dictator, decides how to divide a resource with an anonymous player. The dictator, acting self-interestedly, should offer nothing to the anonymous second player, but in experimental studies, dictators offer much more than nothing. We developed a multilevel selection model to explain why people offer more than nothing in the dictator game. We show that fairness can evolve when population structure emerges from the aggregation and limited dispersal of offspring. We begin with an analytical model that shows how fair behavior can benefit groups by minimizing within-group variance in resources and thereby increasing group fitness. To investigate the generality of this result, we developed an agent-based model with agents that have no information about other agents. We allowed agents to aggregate into groups and evolve different levels of fairness by playing the dictator game for resources to reproduce. This allowed multilevel selection to emerge from the spatiotemporal properties of individual agents. We found that the population structure that emerged under low population densities was most conducive to the evolution of fairness, which is consistent with group selection as a major evolutionary force. We also found that fairness only evolves if resources are not too scarce relative to the lifespan of agents. We conclude that the evolution of fairness could evolve under multilevel selection. Thus, our model provides a novel explanation for the results of dictator game experiments, in which participants often fairly split a resource rather than keeping it all for themselves.

Uveal metastasis from nonsmall cell lung carcinoma with dramatic response to erlotinib.

PURPOSE: To report the case of a never-smoker patient whose initial presentation of metastatic nonsmall cell lung carcinoma was with uveal metastasis, which had a dramatic response to targeted biologic therapy with erlotinib (Tarceva) after failing conventional chemotherapy. METHODS: Case report. A 43-year-old man with uveal metastasis from nonsmall cell lung adenocarcinoma. RESULTS: After failing conventional chemotherapy with carboplatin and taxol, with continued documented rapid growth of the uveal metastasis, treatment was initiated with the targeted biologic agent, erlotinib, which is a protein tyrosine kinase inhibitor of the epidermal growth factor receptor(EGFR). Within 3 days of starting erlotinib, shrinkage of the choroidal lesion was noted, and over the course of the next 3 months, the tumor completely and durably disappeared, with vision improving from hand motion to 20/25. The patient is still alive and well after 3 years, on continued daily oral erlotinib treatment. CONCLUSION: Erlotinib is a well-tolerated newly available Food and Drug Administration-approved oral targeted biologic agent, which may be beneficial in some patients with uveal metastasis from nonsmall cell lung carcinoma, in which an underlying epidermal growth factor receptor mutation is suspected.

Applying informed coding and embedding to design a robust high-capacity watermark.

We describe a new watermarking system based on the principles of informed coding and informed embedding. This system is capable of embedding 1380 bits of information in images with dimensions 240 x 368 pixels. Experiments on 2000 images indicate the watermarks are robust to significant valumetric distortions, including additive noise, low-pass filtering, changes in contrast, and lossy compression. Our system encodes watermark messages with a modified trellis code in which a given message may be represented by a variety of different signals, with the embedded signal selected according to the cover image. The signal is embedded by an iterative method that seeks to ensure the message will not be confused with other messages, even after addition of noise. Fidelity is improved by the incorporation of perceptual shaping into the embedding process. We show that each of these three components improves performance substantially.