36 research outputs found
A Fast Approximate Fault Simulation Method for Power Systems Contingency Selection
Get PDFapplication/pdfAnew contingency analysis method for contingency selection is proposed in this paper. In the method proposed, a fault is simulated by power injections to adjacent buses on the fault devices in ａ pre-fault system, and by essentially a non-iterative linear calculation to avoid recalculation of a Z-matrix or refactor of a Y-matrix. As more accurate load flow calculation is available by the method proposed than by the sensitivity approach, more reliable contingency selection is available, even though the computational speed of the method is a little slower than that of the method using the sensitivity approach. From the IEEE 30 bus example, it is found that the method is satisfactorily applied to the contingency selection from the view of both the accuracy and the computational speed. The error of the method is less than 1％ in voltage and less than 1 degree in phase angle for most fault cases of the IEEE 30 bus system. The computational burden is less than 10％ of that of P-Q decoupled load now method in most fault casesdepartmental bulletin pape
Gold-Nanoparticle-Based Assay for Instantaneous Detection of Nuclear Hormone Receptor−Response Elements Interactions
No full textGold nanoparticles (AuNPs) are widely used as colorimetric probes for biosensing, relying on their unique particle size-dependent and/or interparticle distance-dependent extinction spectrum and solution color. Herein, we describe an AuNP-based colorimetric assay to detect binding interactions between nuclear hormone receptors and their corresponding DNA-binding elements, particularly the human estrogen receptors (ERα and ERβ) and their cognate estrogen response elements (EREs). We found that the protein−DNA (ER−ERE) complexes can stabilize citrate anion-capped AuNPs against salt-induced aggregation to a larger extent than the protein (ER) or the DNA (ERE) alone, due to their unique molecular size and charge properties that provide a strong electrosteric protection. Moreover, our results show that the extent of stabilization is sequence-dependent and can distinguish a single base variation in the ERE associated with minor changes in protein−DNA binding affinity. With this assay, many important parameters of protein−DNA binding events (e.g., sequence selectivity, distinct DNA binding properties of protein subtypes, binding stoichiometry, and sequence-independent transient binding) can be determined instantly without using labels, tedious sample preparations, and sophisticated instrumentation. These benefits, in particular the high-throughput potential, could enable this assay to become the assay of choice to complement conventional techniques for large scale characterization of protein−DNA interactions, a key aspect in biological research
The k-leader and mappings which change the dimensions of topological spaces
No full textFor a Tychonoff space X, let kX be the k-leader of X, dim X the covering dimension of X and Ind X the large inductive dimension of X. We prove: (1) For every n = 1,2,3,...,∞, there exists a regular Lindelof space X such that kX ix normal and dim X = Ind X = 0 ω1, then for every n = 1,2,3,...,∞, there exists an open and closed, continuous map f from a normal space X onto a normal space Y such that dim f^-1 (y) = Ind f^-1 (y) = 0 for each y∊Y and dim X = n > 0 = dim Y = Ind Y.departmental bulletin pape
PPARG Binding Landscapes in Macrophages Suggest a Genome-Wide Contribution of PU.1 to Divergent PPARG Binding in Human and Mouse
Get PDF<div><h3>Background</h3><p>Genome-wide comparisons of transcription factor binding sites in different species can be used to evaluate evolutionary constraints that shape gene regulatory circuits and to understand how the interaction between transcription factors shapes their binding landscapes over evolution.</p> <h3>Results</h3><p>We have compared the PPARG binding landscapes in macrophages to investigate the evolutionary impact on PPARG binding diversity in mouse and humans for this important nuclear receptor. Of note, only 5% of the PPARG binding sites were shared between the two species. In contrast, at the gene level, PPARG target genes conserved between both species constitute more than 30% of the target genes regulated by PPARG ligand in human macrophages. Moreover, the majority of all PPARG binding sites (55–60%) in macrophages show co-occupancy of the lineage-specification factor PU.1 in both species. Exploring the evolutionary dynamics of PPARG binding sites, we observed that PU.1 co-binding to PPARG sites appears to be important for possible PPARG ancestral functions such as lipid metabolism. Thus we speculate that PU.1 may have guided utilization of these species-specific PPARG conserved binding sites in macrophages during evolution.</p> <h3>Conclusions</h3><p>We propose a model in which PU.1 sites may have served as “anchor” loci for the formation of new and functionally relevant PPARG binding sites throughout evolution. As PU.1 is an essential factor in macrophage biology, such an evolutionary mechanism would allow for the establishment of relevant PPARG regulatory modules in a PU.1-dependent manner and yet permit for nuanced regulatory changes in individual species.</p> </div
Global identification of PPARG and RXR binding sites in human macrophages.
No full text<p>A) Table displaying the number identified PPARG peaks. PPARG/RXR peaks represent PPARG peaks that are supported by enrichment in the RXR ChIP-Seq library (RXR here represents RXRA, RXRB and RXRG). B) PPARG and RXR binding profiles across the locus for PDK4 in THP-1 cells. Plotted are the tag counts obtained from the respective ChIP-Seq libraries. C) Distribution of PPARG/RXR binding sites relative to annotated genes obtained from UCSC Genome Browser (built hg18/NCBI36; RefGene table). D) Motif identified <i>de novo</i> at PPARG/RXR binding sites using CisFinder.</p
