The Observations Of The X-Ray Source Hz Herculis-Hercules X-1

NASAESASRCAstronom

The short time-scale light variability of HD 153919 revisited

Using Fourier analysis techniques, the available sets of visual photometric data concerning the X-ray binary HD 153919 are analyzed in order to clear up the controversy on the possible existence or absence of the small-amplitude light variability (T = about 90 min). In this work, great effort has been made to keep a good level of homogeneity and objectivity. The main conclusion is that at the 99.4-percent confidence level, a periodicty (v = 15.5/day) is detected in one data set. In this case, it is possible to conclude that the short time-scale variability does exist. No other self-conclusive detection can be definitely reported; nevertheless, at the 90-percent confidence level, the star has a tendency to vary with characteristic frequencies of about 15/day, 30/day, and possibly higher multiples

An Intracellular Transcriptomic Atlas of the Giant Coenocyte Caulerpa taxifolia

Convergent morphologies have arisen in plants multiple times. In non-vascular and vascular land plants, convergent morphology in the form of roots, stems, and leaves arose. The morphology of some green algae includes an anchoring holdfast, stipe, and leaf-like fronds. Such morphology occurs in the absence of multicellularity in the siphonous algae, which are single cells. Morphogenesis is separate from cellular division in the land plants, which although are multicellular, have been argued to exhibit properties similar to single celled organisms. Within the single, macroscopic cell of a siphonous alga, how are transcripts partitioned, and what can this tell us about the development of similar convergent structures in land plants? Here, we present a de novo assembled, intracellular transcriptomic atlas for the giant coenocyte Caulerpa taxifolia. Transcripts show a global, basal-apical pattern of distribution from the holdfast to the frond apex in which transcript identities roughly follow the flow of genetic information in the cell, transcription-to-translation. The analysis of the intersection of transcriptomic atlases of a land plant and Caulerpa suggests the recurrent recruitment of transcript accumulation patterns to organs over large evolutionary distances. Our results not only provide an intracellular atlas of transcript localization, but also demonstrate the contribution of transcript partitioning to morphology, independent from multicellularity, in plants