frataxin gene, the human b T cell receptor locus sequence and two yeast chromosomes. These sequences range in size from 3 kb up to 700 kb. A World Wide Web server interface at c3.biomath.mssm.edu/trf.html has been established for automated use of the program.

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We study the perturbative dynamics of noncommutative field theories on Rd, and find an intriguing mixing of the UV and the IR. High energies of virtual particles in loops produce non-analyticity at low momentum. Consequently, the low energy effective action is singular at zero momentum even when the original noncommutative field theory is massive. Some of the nonplanar diagrams of these theories are divergent, but we interpret these divergences as IR divergences and deal with them accordingly. We explain how this UV/IR mixing arises from the underlying noncommutativity. This phenomenon is reminiscent of the channel duality of the double twist diagram in open string theory.

www.ASEBA.org $0.50 Yes The 2001 Teacher’s Report Form (TRF) is a teacher-report measure that assesses problem behavior and can identify 8 syndromes. It also assesses academic performance and adaptive functioning. One or more teachers, or other school personnel, who have known the child

Telomere length in human cells is controlled by a homeostasis mechanism that involves telomerase and the negative regulator of telomere length, TRF1 (TTAGGG repeat binding factor 1). Here we report that TRF2, a TRF1-related protein previously implicated in protection of chromosome ends, is a second

Human telomeres contain two related telomeric DNA-

Using the recent advances in our understanding of non-perturbative aspects of type II strings we show how non-trivial exact results for N = 2 quantum field theories can be reduced to T-dualities of string theory. This is done by constructing a local geometric realization of quantum field theories together with a local application of mirror symmetry. This construction is not based on any duality conjecture and thus reduces non-trivial quantum field theory results to much better understood T-dualities of type II strings. Moreover it can be used in principle to construct in a systematic way the vacuum structure for arbitrary N = 2 gauge theories with matter representations. September

Small RNA guides—microRNAs, small interfering RNAs, and repeat-associated small interfering RNAs, 21 to 30 nucleotides in length—shape diverse cellular pathways, from chromosome architecture to stem cell maintenance. Fifteen years after the discovery of RNA silencing, we are only just beginning to understand the depth and complexity of how these RNAs regulate gene expression and to consider their role in shaping the evolutionary history of higher eukaryotes. In 1969, Britten and Davidson proposed that RNAs specify which genes are turned on and which are turned off in eukaryotic cells (1). Their elegant idea was that the base-pairing rules of Watson and Crick could solve the problem of eukaryotic gene regulation. With the subsequent discovery of protein transcription factors—there are perhaps 1850 in humans—the idea that a diverse array of

homodimerization [12, 14]. The proteins do not form heterodimers [12]. Although related, the two proteins have very different functions at telomeres. TRF1 func-tions as a negative regulator of telomere length, acting in cis to control access of telomerase [9, 15], whereas

solutions to the end replication problem have been doc-