Clonal Interference, Multiple Mutations, and Adaptation in Large Asexual Populations

Two important problems affect the ability of asexual populations to accumulate beneficial mutations, and hence to adapt. First, clonal interference causes some beneficial mutations to be outcompeted by more-fit mutations which occur in the same genetic background. Second, multiple mutations occur in some individuals, so even mutations of large effect can be outcompeted unless they occur in a good genetic background which contains other beneficial mutations. In this paper, we use a Monte Carlo simulation to study how these two factors influence the adaptation of asexual populations. We find that the results depend qualitatively on the shape of the distribution of the effects of possible beneficial mutations. When this distribution falls off slower than exponentially, clonal interference alone reasonably describes which mutations dominate the adaptation, although it gives a misleading picture of the evolutionary dynamics. When the distribution falls off faster than exponentially, an analysis based on multiple mutations is more appropriate. Using our simulations, we are able to explore the limits of validity of both of these approaches, and we explore the complex dynamics in the regimes where neither are fully applicable.Comment: 24 pages, 5 figure

Digital receiver study and implementation

Computer software was developed which makes it possible to use any general purpose computer with A/D conversion capability as a PSK receiver for low data rate telemetry processing. Carrier tracking, bit synchronization, and matched filter detection are all performed digitally. To aid in the implementation of optimum computer processors, a study of general digital processing techniques was performed which emphasized various techniques for digitizing general analog systems. In particular, the phase-locked loop was extensively analyzed as a typical non-linear communication element. Bayesian estimation techniques for PSK demodulation were studied. A hardware implementation of the digital Costas loop was developed

The New Sexy: A Rhetorical Analysis of Sherlock

In recent history, there have been movements advocating for conversation and change regarding traditional gender roles. As a central part of culture, British television has not escaped this scrutiny. BBC\u27s crime drama Sherlock directed by Steven Moffat has received both critical acclaim and attention from the general public for its portrayal of women. In this essay, we venture into this conversation, and explore portrayals of existing gender roles and how the writers of the show choose to dissent with the audience\u27s expectations of gender portrayal. We examine connections between past and present portrayals of the classic character, Sherlock Holmes, and how these portrayals oppose gender stereotypes. Four methods are examined in this essay to explore the portrayal of women and gender roles in Sherlock. Through strategic use of narrative, the unique way in which the plot is constructed; visuals, the persuasive use of motifs and symbolism; and language, or how word choice assists the viewer in understanding the underlying assumptions of the characters and rhetors. We chose to explore issues of gender roles and how stereotypes are refuted in the episode, “A Scandal in Belgravia,” because it has been the target of criticism for its portrayal of women. We conclude that the scriptwriters of Sherlock use rhetorical devices to challenge the audience\u27s assumptions and to dissent against the way gender norms are typically portrayed on television. Ultimately, “A Scandal in Belgravia” breathes new life into a classic literary character, redefining gender expectations for a modern audience

Task ll Report, Part 2: Evaluation of Water Supplies in the Red River, Dix River, and Mainstem Watersheds of the Kentucky River

This study was part of a larger study of water supplies throughout the Kentucky River Basin conducted by the Kentucky Water Resources Research Institute for the Kentucky River Authority. This report examines municipal and private water supplies in the Red River, Dix River, and mainstem Kentucky River watersheds. Municipal supplies which depend on the mainstem Kentucky River, and municipal and private supplies in the North, South, and Middle Fork watersheds of the Kentucky River basin are examined in separate reports

CD4+CD25+ T regulatory cells from FIV+ cats induce a unique anergic profile in CD8+ lymphocyte targets

Abstract Background Using the FIV model, we reported previously that CD4+CD25+ T regulatory (Treg) cells from FIV+ cats are constitutively activated and suppress CD4+CD25- and CD8+ T cell immune responses. In an effort to further explore Treg-mediated suppression, we asked whether Treg cells induce anergy through the alteration of production of cyclins, cyclin-dependent kinases and their inhibitors. Results Lymphocytes were obtained from control or FIV+ cats and sorted by FACS into CD4+CD25+ and CD8+ populations. Following co-culture with CD4+CD25+ cells, CD8+ targets were examined by Western blot for changes in cyclins D3, E and A, retinoblastoma (Rb) protein, as well as the cyclin dependent kinase inhibitor p21cip1. Following co-culture with CD4+CD25+cells, we observed up-regulation of p21cip1 and cyclin E, with down-regulation of cyclin D3, in CD8+ cells from FIV+ cats. As expected, CD8+ targets from control cats were quiescent with little up-regulation of p21cip1 and cyclin E. There was also a lack of Rb phosphorylation in CD8+ targets consistent with late G1 cell cycle arrest. Further, IL-2 mRNA was down regulated in CD8+ cells after co-culture with CD4+CD25+ Treg cells. Following CD4+CD25+ co-culture, CD8+ targets from FIV+ cats also had increased Foxp3 mRNA expression; however, these CD8+Foxp3+ cells did not exhibit suppressor function. Conclusions Collectively, these data suggest that CD4+CD25+ Treg cells from FIV+ cats induce CD8+ anergy by disruption of normal G1 to S cell cycle progression.</p

Dielectronic Resonance Method for Measuring Isotope Shifts

Longstanding problems in the comparison of very accurate hyperfine-shift measurements to theory were partly overcome by precise measurements on few-electron highly-charged ions. Still the agreement between theory and experiment is unsatisfactory. In this paper, we present a radically new way of precisely measuring hyperfine shifts, and demonstrate its effectiveness in the case of the hyperfine shift of $4s\_{1/2}$ and $4p\_{1/2}$ in $^{207}\mathrm{Pb}^{53+}$. It is based on the precise detection of dielectronic resonances that occur in electron-ion recombination at very low energy. This allows us to determine the hyperfine constant to around 0.6 meV accuracy which is on the order of 10%

Generalized Geologic Map for Land-Use Planning: Pike County, Kentucky

This map is not intended to be used for selecting individual sites. Its purpose is to inform land-use planners, government officials, and the public in a general way about geologic bedrock conditions that affect the selection of sites for various purposes. The properties of thick soils may supercede those of the underlying bedrock and should be considered on a site-to-site basis. At any site, it is important to understand the characteristics of both the soils and the underlying rock