Although regulation of histone methylation is believed to contribute to embryonic stem cell (ESC) self-renewal, the mechanisms remain obscure. We show here that the histone H3 trimethyl lysine 4 (H3K4me3) demethylase, KDM5B, is a downstream Nanog target and critical for ESC self-renewal. Although KDM5B is believed to function as a promoter-bound repressor, we find that it paradoxically functions as an activator of a gene network associated with self-renewal. ChIP-Seq reveals that KDM5B is predominantly targeted to intragenic regions and that it is recruited to H3K36me3 via an interaction with the chromodomain protein MRG15. Depletion of KDM5B or MRG15 increases intragenic H3K4me3, increases cryptic intragenic transcription, and inhibits transcriptional elongation of KDM5B target genes. We propose that KDM5B activates self-renewal-associated gene expression by repressing cryptic initiation and maintaining an H3K4me3 gradient important for productive transcriptional elongation.

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The magnetic flux rope is among the most fundamental magnetic configurations in plasma. Although its presence after solar eruptions has been verified by spacecraft measurements near Earth, its formation on the Sun remains elusive, yet is critical to understanding a broad spectrum of phenomena. Here we study the dynamic formation of a magnetic flux rope during a classic two-ribbon flare. Its feet are identified unambiguously with conjugate coronal dimmings completely enclosed by irregular bright rings, which originate and expand outward from the far ends of flare ribbons. The expansion is associated with the rapid ribbon separation during the flare main phase. Counting magnetic flux through the feet and the ribbon-swept area reveals that the rope’s core is more twisted than its average of four turns. It propagates to the Earth as a typical magnetic cloud possessing a similar twist profile obtained by the Grad-Shafranov reconstruction of its three dimensional structure.

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A thermoelectric energy harvester powered wireless sensor networks (WSNs) module designed for building energy management (BEM) applications is built and tested in this work. An analytic thermoelectric generator (TEG) electrical model is built and verified based on parameters given in manufacturer data sheets of Bismuth Telluride TEGs. A charge pump/switching regulator two-stage ultra-low voltage step-up DC/DC converter design is presented in this work to boost the <0.5 V output voltage of TEG to usable voltage level for WSN (3.3 V). The design concept, device simulation, circuits schematic, and the measurement results are presented in detail. The prototype device test results show 25% end-to-end conversion efficiency in a wide range of input temperatures/voltages. Further tests demonstrate that the proposed thermoelectric generator design can effectively power WSN module which operates with a 1.7% duty cycle (5.8 seconds measurement time interval) when the prototype is placed on a typical wall-mount heater (60 ∘ C surface temperature). The thermoelectric energy harvesting powered WSN demonstrates duty cycles significantly higher than the required duty cycle for BEM WSN applications.

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