The American Wedding March

https://digitalcommons.library.umaine.edu/mmb-ps/1768/thumbnail.jp

St. Patricks Day is a Bad Day for Coons / words by Irving Jones

Cover: photo of Lew Dockstader in blackface; Music Supplement of the New York Journal and Advertiser, Sunday, Sept. 8, 1901; Publisher: Sol Bloom (New York)https://egrove.olemiss.edu/sharris_b/1019/thumbnail.jp

Coon Coon Coon / music by Leo. Friedman; words by Gene Jefferson

Cover: drawing of three African American male faces; photo inset of Irving Jones; text reads: The most successful song hit of 1901. As introduced and sung by Lew Dockstader.; Publisher: Sol Bloom (Chicago)https://egrove.olemiss.edu/sharris_b/1013/thumbnail.jp

Mister Morton, Stop Your Courtin\u27 / music by Frederick V. Bowers; words by Charles Horwitz

Cover: drawing of a woman peering from behind a tree; photo inset of The Nichols Sisters; Publisher: Sol Bloom (Chicago)https://egrove.olemiss.edu/sharris_b/1025/thumbnail.jp

My Dusky Queen / music by J. B. Oliver; words by Jack Fay

Cover: drawing of a woman playing banjo; photo inset of Bonita; Music Supplement of the New York Journal and Advertiser, Sunday, May 5, 1901; Publisher: Sol Bloom (New York)https://egrove.olemiss.edu/sharris_b/1026/thumbnail.jp

Protein Structural Modularity and Robustness Are Associated with Evolvability

Theory suggests that biological modularity and robustness allow for maintenance of fitness under mutational change, and when this change is adaptive, for evolvability. Empirical demonstrations that these traits promote evolvability in nature remain scant however. This is in part because modularity, robustness, and evolvability are difficult to define and measure in real biological systems. Here, we address whether structural modularity and/or robustness confer evolvability at the level of proteins by looking for associations between indices of protein structural modularity, structural robustness, and evolvability. We propose a novel index for protein structural modularity: the number of regular secondary structure elements (helices and strands) divided by the number of residues in the structure. We index protein evolvability as the proportion of sites with evidence of being under positive selection multiplied by the average rate of adaptive evolution at these sites, and we measure this as an average over a phylogeny of 25 mammalian species. We use contact density as an index of protein designability, and thus, structural robustness. We find that protein evolvability is positively associated with structural modularity as well as structural robustness and that the effect of structural modularity on evolvability is independent of the structural robustness index. We interpret these associations to be the result of reduced constraints on amino acid substitutions in highly modular and robust protein structures, which results in faster adaptation through natural selection

Modelling rapid TeV variability of PKS 2155-304

We present theoretical modelling for the very rapid TeV variability of PKS 2155--304 observed recently by the H.E.S.S. experiment. To explain the light-curve, where at least five flaring events were well observed, we assume five independent components of a jet that are characterized by slightly different physical parameters. An additional, significantly larger component is used to explain the emission of the source at long time scales. This component dominates the emission in the X-ray range, whereas the other components are dominant in the TeV range. The model used for our simulation describes precisely the evolution of the particle energy spectrum inside each component and takes into account light travel time effects. We show that a relatively simple synchrotron self-Compton scenario may explain this very rapid variability. Moreover, we find that absorption of the TeV emission inside the components due to the pair creation process is negligible.Comment: 6 pages, 1 figure, Accepted for publication in MNRAS the Main Journa

A synchrotron self-Compton scenario for the very high energy gamma-ray emission of the radiogalaxy M87

M87 is the first extragalactic source detected in the TeV range that is not a blazar. With the increasing performances of ground-based Cherenkov telescopes, we can now probe the variability in the gamma-ray flux at small timescales, thus putting strong constraints on the size of the emitting zone. A modification of standard emission models of TeV blazars appears necessary to account for the gamma-ray observations despite this misalignment. We explain TeV gamma-ray spectra and fast variability of M87 by invoking an emission zone close to the central supermassive black hole, which is filled with several plasma blobs moving in the large opening angle of the jet formation zone. We develop a new multi-blob synchrotron self-Compton (SSC) model with emitting blobs beyond the Alfven surface in the jet, at a distance of about 100 r_g from the central engine. This model is explicitly adapted to deal with large viewing angles and moderate values of the Lorentz factor inferred from (general relativistic) magnetohydrodynamic models of jet formation. This scenario can account for the recent gamma-ray observations of M87 made by the High Energy Stereoscopic System (H.E.S.S.) telescope array. We find individual blob radii of about 10^{14} cm, which is compatible with the variability on timescales of days recently reported by the H.E.S.S. collaboration and is of the order of the black hole gravitational radius. Predictions of the very high energy emission for three other sources with extended optical or X-ray jet which could be misaligned blazars still with moderate beaming are presented for one Seyfert 2 radiogalaxy, namely Cen A, one peculiar BL Lac, PKS 0521-36, and one quasar, 3C 273.Comment: 10 pages, 8 figures; accepted in A&

Human genetics and clinical aspects of neurodevelopmental disorders

This chapter traverses contemporary understandings of the genetic architecture of human disease, and explores the clinical implications of the current state of knowledge. Many different classes of genetic mutations have been implicated as being involved in predisposition to certain diseases, and researchers are continually uncovering other means by which genetics plays an important role in human disease, such as with somatic genetic mosaicism. Putative “de novo” mutations can represent cases of parental mosaicism (including in the germline), which could be revealed by careful genotyping of parental tissues other than peripheral blood lymphocytes. There is an increasingly rich literature regarding rare mutations with seemingly large phenotypic effects. Privacy concerns have added to the difficulties of implementing genomics-guided medicine. With the advent of exome and whole genome sequencing (WGS), one needs to focus again on families over several generations, so as to attempt to minimize genetic differences, locus heterogeneity and environmental influences

Evolutionary origins of invasive populations

What factors shape the evolution of invasive populations? Recent theoretical and empirical studies suggest that an evolutionary history of disturbance might be an important factor. This perspective presents hypotheses regarding the impact of disturbance on the evolution of invasive populations, based on a synthesis of the existing literature. Disturbance might select for life-history traits that are favorable for colonizing novel habitats, such as rapid population growth and persistence. Theoretical results suggest that disturbance in the form of fluctuating environments might select for organismal flexibility, or alternatively, the evolution of evolvability. Rapidly fluctuating environments might favor organismal flexibility, such as broad tolerance or plasticity. Alternatively, longer fluctuations or environmental stress might lead to the evolution of evolvability by acting on features of the mutation matrix. Once genetic variance is generated via mutations, temporally fluctuating selection across generations might promote the accumulation and maintenance of genetic variation. Deeper insights into how disturbance in native habitats affects evolutionary and physiological responses of populations would give us greater capacity to predict the populations that are most likely to tolerate or adapt to novel environments during habitat invasions. Moreover, we would gain fundamental insights into the evolutionary origins of invasive populations