80 research outputs found
Genus Two Surface and Quarter BPS Dyons: The Contour Prescription
Following the suggestion of hep-th/0506249 and hep-th/0612011, we represent
quarter BPS dyons in N=4 supersymmetric string theories as string network
configuration and explore the role of genus two surfaces in determining the
spectrum of such dyons. Our analysis leads to the correct contour prescription
for integrating the partition function to determine the spectrum in different
domains of the moduli space separated by the walls of marginal stability.Comment: LaTeX file, 25 page
On the smoothness of multi-M2 brane horizons
We calculate the degree of horizon smoothness of multi- -brane solution
with branes along a common axis. We find that the metric is generically only
thrice continuously differentiable at any of the horizons. The four-form field
strength is found to be only twice continuously differentiable. We work with
Gaussian null-like co-ordinates which are obtained by solving geodesic
equations for multi- brane geometry. We also find different, exact
co-ordinate transformations which take the metric from isotropic co-ordinates
to co-ordinates in which metric is thrice differentiable at the horizon. Both
methods give the same result that the multi- brane metric is only thrice
continuously differentiable at the horizon.Comment: 24 pages, reference added, modified equation for non-singularity of
metri
Quantitative profiling of selective Sox/POU pairing on hundreds of sequences in parallel by Coop-seq
© The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research. Cooperative binding of transcription factors is known to be important in the regulation of gene expression programs conferring cellular identities. However, current methods to measure cooperativity parameters have been laborious and therefore limited to studying only a few sequence variants at a time. We developed Coop-seq (cooperativity by sequencing) that is capable of efficiently and accurately determining the cooperativity parameters for hundreds of different DNA sequences in a single experiment. We apply Coop-seq to 12 dimer pairs from the Sox and POU families of transcription factors using 324 unique sequences with changed half-site orientation, altered spacing and discrete randomization within the binding elements. The study reveals specific dimerization profiles of different Sox factors with Oct4. By contrast, Oct4 and the three neural class III POU factors Brn2, Brn4 and Oct6 assemble with Sox2 in a surprisingly indistinguishable manner. Two novel half-site configurations can support functional Sox/Oct dimerization in addition to known composite motifs. Moreover, Coop-seq uncovers a nucleotide switch within the POU half-site when spacing is altered, which is mirrored in genomic loci bound by Sox2/Oct4 complexes.Link_to_subscribed_fulltex
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