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Anne Case provided particularly helpful and insightful comments which eliminated much confusion. I thank especially Richard Wilkinson, whose work and suggestions have inspired much of this work. Although I have tried to construct a model that captures what seems to me to be the spirit of his ideas, I bear sole responsibility for the results. Helpful(More)
When, where and how is the head-tail axis of the embryo set up during development? These are such fundamental and intensely studied questions that one might expect them to have been answered long ago. Not so; we still understand very little about the cellular or molecular mechanisms that lead to the orderly arrangement of body elements along the head-tail(More)
We present new evidence on the distribution of the ex ante risk premium based on a multi-year survey of Chief Financial Officers (CFOs) of U.S. corporations. We have responses from surveys conducted from the second quarter of 2000 through the second quarter of 2003. We find evidence that the one-year risk premium is highly variable through time, while the(More)
In vertebrate embryos, the earliest definitive marker for the neural plate, which will give rise to the entire central nervous system, is the transcription factor Sox2. Although some of the extracellular signals that regulate neural plate fate have been identified, we know very little about the mechanisms controlling Sox2 expression and thus neural plate(More)
We describe how episodic illiquidity arises from a breakdown in cooperation between market participants. We first solve a one-period trading game in continuous-time, using an asset pricing equation that accounts for the price impact of trading. Then, in a multi-period framework, we describe an equilibrium in which traders cooperate most of the time through(More)
We have identified fullback and fullback-like, two Xenopus laevis neurotrophin receptor homolog (NRH1) genes. The sequences of Fullback and Fullback-like are very similar to that of the neurotrophin receptor p75NTR, in both their extracellular and their intracellular domains. As their names imply, fullback and fullback-like are expressed in essentially(More)
The Mad (mothers against decapentaplegic) gene in Harvard University Drosophila and the related Sma genes in Caenorhabditis Cambridge, Massachusetts 02138-2019 elegans have been implicated in signal transduction by in vertebrates and shown to mediate TGF␤ family signals Berkeley, California 94720-3204 in these organisms as well. To date, there are five(More)
Saccharomyces cerevisiae Scc2 binds Scc4 to form an essential complex that loads cohesin onto chromosomes. The prevalence of Scc2 orthologs in eukaryotes emphasizes a conserved role in regulating sister chromatid cohesion, but homologs of Scc4 have not hitherto been identified outside certain fungi. Some metazoan orthologs of Scc2 were initially identified(More)