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- J T Chang
- Mathematical biosciences
- 1996

A Markov model of evolution of characters on a phylogenetic tree consists of a tree topology together with a specification of probability transition matrices on the edges of the tree. Previous work has shown that, under mild conditions, the tree topology may be reconstructed, in the sense that the topology is identifiable from knowledge of the joint… (More)

- Yuval Kluger, Ronen Basri, Joseph T Chang, Mark Gerstein
- Genome research
- 2003

Global analyses of RNA expression levels are useful for classifying genes and overall phenotypes. Often these classification problems are linked, and one wants to find "marker genes" that are differentially expressed in particular sets of "conditions." We have developed a method that simultaneously clusters genes and conditions, finding distinctive… (More)

- J T Chang
- Mathematical biosciences
- 1996

A fundamental problem in reconstructing the evolutionary history of a set of species is to infer the topology of the evolutionary tree that relates those species. A statistical method for estimating such a topology from character data is called consistent if, given data from more and more characters, the method is sure to converge to the true topology. A… (More)

- Joseph T. Chang
- 1991

Suppose that the evolution of a character possessed by a number of current species is modelled as a Markov random eld on an evolutionary tree. Suppose that for each pair of current species we know the joint probability distribution of the pair of characters possessed by that pair of species. We give conditions under which the evolutionary tree can be… (More)

- Joseph T. Chang, J. Chang
- 1999

Previous study of the time to a common ancestor of all present-day individuals has focused on models in which each individual has just one parent in the previous generation. For example, “mitochondrial Eve” is the most recent common ancestor (MRCA) when ancestry is defined only through maternal lines. In the standard Wright-Fisher model with population size… (More)

- T E Klein, J T Chang, +11 authors R B Altman
- The pharmacogenomics journal
- 2001

- Joseph T. Chang
- 1996

Yale University and University of California, Berkeley Let Sn n ≥ 0 be a random walk having normally distributed increments with mean θ and variance 1, and let τ be the time at which the random walk first takes a positive value, so that Sτ is the first ladder height. Then the expected value EθSτ, originally defined for positive θ, may be extended to be an… (More)

Stochastic gradient descent is a general algorithm that includes LMS, on-line backpropagation, and adaptive k-means clustering as special cases. The standard choices of the learning rate (both adap-tive and xed functions of time) often perform quite poorly. In contrast, our recently proposed class of \search then converge" (STC) learning rate schedules… (More)

- Douglas L T Rohde, Steve Olson, Joseph T Chang
- Nature
- 2004

If a common ancestor of all living humans is defined as an individual who is a genealogical ancestor of all present-day people, the most recent common ancestor (MRCA) for a randomly mating population would have lived in the very recent past. However, the random mating model ignores essential aspects of population substructure, such as the tendency of… (More)

- Carolyn M Yrigollen, Summer S Han, +5 authors Elena L Grigorenko
- Biological psychiatry
- 2008

BACKGROUND
Autism spectrum disorders (ASD) are neurodevelopmental disorders of complex etiology, with a recognized substantial contribution of heterogeneous genetic factors; one of the core features of ASD is a lack of affiliative behaviors.
METHODS
On the basis of the existing literature, in this study we examined the hypothesis of allelic associations… (More)