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)

Geared toward readers already acquainted with special relativity, this book transcends the view of theory as a working tool to answer natural questions: What is ...

In the October 1937 number of Philosophy of Science Lindsay has made certain criticisms of the adequacy of the “operational method” of analyzing and giving meaning to the concepts of physics, documenting his criticisms chiefly from my own writings. In these criticisms he has made statements as to the method which I would by no means accept. This is not characteristic of his paper only, for I have seldom indeed seen a printed discussion of the method which I would accept (...) as being an adequate or sometimes even fair representation of what I understand by it. It will perhaps pay therefore if I attempt to state what I conceive it to be all about, particularly since I have never attempted such a comprehensive statement and since my own ideas on the subject have been developing since I first wrote in the Logic of Modern Physics. For one reason I have hesitated to do this, for fear of seeming to subscribe to the not uncommon idea that we are dealing with some elaborate and profound new theory of the nature of knowledge or of meaning. I believe that I myself have never talked of “operationalism” or “operationism”, but I have a distaste for these grandiloquent words which imply something more philosophic and esoteric than the simple thing that I see. What we are here concerned with is an observation and description of methods which at least some physicists had already, perhaps unconsciously, adopted and found successful—the practise of the methods already existed. What I have attempted is to analyze these successful methods, not to set up a philosophical system and a theory of the properties that any method must have if it hopes to be successful. Since I was concerned with a technique already extant, my principal method of getting others to see what the technique involved has been to exhibit examples of the technique in action, rather than to attempt any exhaustive characterization of the technique itself. (shrink)

History of Science is a many-sided subject, permitting approach from the point of view of various human interests, and presenting a wide variety of problems, many of them paradoxical and perhaps not capable of satisfactory solution. In the following it will probably seem to the reader a number of times that I am talking at cross purposes. Anything that I can say is of necessity limited by my background as a physicist.

As militarization of bodies politic continues apace the world over, as military organizations again reveal themselves as primary political, economic and cultural forces in many societies, we argue that the emergent and potentially dominant form of political economic organization is a species of neo-feudal corporatism. Drawing upon Bourdieu, we theorize bodies politic as living habitus. Bodies politic are prepared for war and peace through new mediations, powerful means of public pedagogy. The process of militarization requires the generation of new, antagonistic (...) evaluations of other bodies politic. Such evaluations are inculcated via these mediations, the movement of meanings across time and space, between formerly disparate histories, places, and cultures. New mediations touch new and different aspects of the body politic: its eyes, its ears, its organs, but they are consistently targeted at the formation of dispositions, the prime movers of action. (shrink)