Transcriptional silencing may not necessarily depend on the continuous residence of a sequence‐specific repressor at a control element and may act via a “hit and run” mechanism. Due to limitations in assays that detect transcription factor (TF) binding, such as chromatin immunoprecipitation followed by high‐throughput sequencing (ChIP‐seq), this phenomenon may be challenging to detect and therefore its prevalence may be underappreciated. To explore this possibility, erythroid gene promoters that are regulated directly by GATA1 in an inducible system are analyzed. It (...) is found that many regulated genes are bound immediately after induction of GATA1 but the residency of GATA1 decreases over time, particularly at repressed genes. Furthermore, it is shown that the repressive mark H3K27me3 is seldom associated with bound repressors, whereas, in contrast, the active (H3K4me3) histone mark is overwhelmingly associated with TF binding. It is hypothesized that during cellular differentiation and development, certain genes are silenced by repressive TFs that subsequently vacate the region. Catching such repressor TFs in the act of silencing via assays such as ChIP‐seq is thus a temporally challenging prospect. The use of inducible systems, epitope tags, and alternative techniques may provide opportunities for detecting elusive “hit and run” transcriptional silencing. Also see the video abstract here https://youtu.be/vgrsoP_HF3g. (shrink)

© 2017. The American Astronomical Society. All rights reserved.We present new observations of the low-mass companion to HD 984 taken with the Gemini Planet Imager as a part of the GPI Exoplanet Survey campaign. Images of HD 984 B were obtained in the J and H bands. Combined with archival epochs from 2012 and 2014, we fit the first orbit to the companion to find an 18 au orbit with a 68% confidence interval between 14 and 28 au, an eccentricity (...) of 0.18 with a 68% confidence interval between 0.05 and 0.47, and an inclination of 119°with a 68% confidence interval between 114°and 125°. To address the considerable spectral covariance in both spectra, we present a method of splitting the spectra into low and high frequencies to analyze the spectral structure at different spatial frequencies with the proper spectral noise correlation. Using the split spectra, we compare them to known spectral types using field brown dwarf and low-mass star spectra and find a best-fit match of a field gravity M6.5 ±1.5 spectral type with a corresponding temperature of K. Photometry of the companion yields a luminosity of log=2.88 ± 0.07 dex with DUSTY models. Mass estimates, again from DUSTY models, find an age-dependent mass of 34 ±1 to 95 ±4 M Jup. These results are consistent with previous measurements of the object. (shrink)

Study of the European Enlightenment could do with a fillip. Perhaps the best tonic we have is combining the close reading of significant works with the study of print history and reader reception....

Study of the European Enlightenment could do with a fillip. Perhaps the best tonic we have is combining the close reading of significant works with the study of print history and reader reception....

Two recent papers by Michael Burke bearing upon the persistence of people and commonplace things illustrate the fact that the quest for synchronic ontological economy is likely to encourage a disturbing diachronic proliferation of entities. This discussion argues that Burke's promise of ontological economy is seriously compromised by the fact that his proposed metaphysic does violence to standard intuitions concerning the persistence of people and commonplace things. In effect, Burke would have us achieve synchronic economy (rejection of coincident entities) by (...) postulating strongly counterintuitive transtemporal claims of numerical diversity. The argument is made that the price of Burkean economy is too high. (shrink)

Only those whose work and interests have led them to notice it, will have realised, in all probability, the remarkable extent to which the term organization has gained currency, or acquired new and special emphasis, throughout the entire range of scientific and sociological literature during the last ten or twenty years.In biology and bio-chemistry organization has been discussed or used as a technical term, mostly since 1930 by at least thirty well-known authors; amongst the more prominent are Huxley, Wilson, Woodger, (...) Cannon, Waddington, McDougall, Needham, Block, Hopkins and Sherrington. Under this magic term some authors refer to the physico-chemical nature of the cell or cytoplasm, and usually with special reference to selective or directive catalysis; others to the general constitution or structure of the organism and almost indistinguishable from general morphology and physiology; others to embryological development as such ; others more especially to “relations” between cells, organs and structural parts, often in an abstract sense; others refer more particularly to a hypothetical integrating and/or co-ordinating factor : a few refer to re-constitution from dissociated cells as observed in experiments with Sponges and Hydroids. (shrink)

Eric Olsen argues from the fact that we once existed as fetal individuals to the conclusion that the Standard View of personal identity is mistaken. I shall establish that a similar argument focusing upon dead people opposes Olson’s favored Biological View of personal identity.

Two recent papers by Michael Burke bearing upon the persistence of people and commonplace things illustrate the fact that the quest for synchronic ontological economy is likely to encourage a disturbing diachronic proliferation of entities. This discussion argues that Burke’s promise of ontological economy is seriously compromised by the fact that his proposed metaphysic does violence to standard intuitions concerning the persistence of people and commonplace things. In effect, Burke would have us achieve synchronic economy (rejection of coincident entities) by (...) postulating strongly counterintuitive transtemporal claims of numerical diversity. The argument is made that the price of Burkean economy is too high. (shrink)