Residence-time distributions for chaotic flows in pipes

In this paper we derive two rigorous properties of residence-time distributions for flows in pipes and mixers motivated by computational results of Khakhar et al. [Chem. Eng. Sci. 42, 2909 (1987)], using some concepts from ergodic theory. First, a curious similarity between the isoresidence-time plots and Poincaré maps of the flow observed in Khakhar et al. is resolved. It is shown that in long pipes and mixers, Poincaré maps can serve as a useful guide in the analysis of isoresidence-time plots, but the two are not equivalent. In particular, for long devices isoresidence-time sets are composed of orbits of the Poincaré map, but each isoresidence-time set can be comprised of many orbits. Second, we explain the origin of multimodal residence-time distributions for nondiffusive motion of particles in pipes and mixers. It is shown that chaotic regions in the Poincaré map contribute peaks to the appropriately defined and rescaled axial distribution functions

Solidarity and the Root of the Ethical

This is the text of The Lindley Lecture for 2008, given by David Wiggins, a British philosopher

A Single-Molecule Hershey-Chase Experiment

Ever since Hershey and Chase used phages to establish DNA as the carrier of genetic information in 1952, the precise mechanisms of phage DNA translocation have been a mystery. While bulk measurements have set a time scale for in vivo DNA translocation during bacteriophage infection, measurements of DNA ejection by single bacteriophages have only been made in vitro. Here, we present direct visualization of single bacteriophages infecting individual Escherichia coli cells. For bacteriophage lambda, we establish a mean ejection time of roughly 5 minutes with significant cell-to-cell variability, including pausing events. In contrast, corresponding in vitro single-molecule ejections take only 10 seconds to reach completion and do not exhibit significant variability. Our data reveal that the velocity of ejection for two different genome lengths collapses onto a single curve. This suggests that in vivo ejections are controlled by the amount of DNA ejected, in contrast with in vitro DNA ejections, which are governed by the amount of DNA left inside the capsid. This analysis provides evidence against a purely intrastrand repulsion based mechanism, and suggests that cell-internal processes dominate. This provides a picture of the early stages of phage infection and sheds light on the problem of polymer translocation

Gold Is Every Man\u27s Opportunity Castration Anxiety and the Economic Venture In \u3ci\u3eDeadwood\u3c/i\u3e

In one of the most famous and quoted passages from The Eighteenth Brumaire of Louis Bonaparte, Karl Marx observes, Men make their own history, but not spontaneously, under conditions they have chosen for themselves; rather on terms immediately existing, given and handed down to them. While the historical conditions that engendered the Black Hills gold rush of the mid-1870s were more forced by and upon the participants than handed to them, Marx\u27s argument resonates loudly with the anti-romantic project of HBO\u27s critically acclaimed Western, Deadwood. Series creator David Milch makes a similar point about the town of Deadwood: The only reason the town of Deadwood exists is gold. Milch bluntly discards the Western genre\u27s foundational ideology of self-determination, considering these principles a delusion that obscures the material realities of the late nineteenth century. Were it not for the curious oscillation of history and economy, of time and theft, toward a mining free-for-all zone in the Black Hills, it seems unlikely that the war cries of noninterference and isolationism would have sounded so consistently throughout the camp of prospectors. To that end, Milch\u27s series goes to great lengths to remind viewers of the historical contingencies that underlie Deadwood\u27s dreams of separatism and self-rule. Deadwood contributes to recent revisions of the Western precisely by calling attention to the economic and historical conditions that incubated the illusory myth of selfreliant individualism in the frontier space. In part, what the series overturns is the popular and fantastical treatment of the frontier as a blank space where the rugged loner could test out his preformed codes of atomized republicanism. Or, as Richard Slotkin has put it, to promote the fabled version of the West is to turn from the tragedy of fraternal strife of labor and capital and embrace the classic quest of the republic\u27s heroic ages, the mission to bring light, law, liberty, Christianity, and commerce to the savage places of the earth. If Slotkin identifies a version of the West that is mythic representation, then certainly Deadwood is a sort of grimacing antimyth. The show foregrounds a distribution of power in the Great Plains that is gilded with gold. By focusing on the struggle of the camp and its individual inhabitants against state intervention, Deadwood forces us to consider the historical factors that placed the contested, lawless matrix of the Black Hills in conflict and eventual compliance with the nation and its capitalist harbingers. In this article, we argue that the thematic movement of Deadwood hinges on the secondseason episode Almagmation and Capital, which marks the series\u27 transition from a concern with lawlessness to a focus on the economics of western settlement and incorporation. We explore how the episode\u27s curiously abundant representations of castration contain a fundamental anxiety over national annexation and loss of economic autonomy. Ultimately, Deadwood reconfigures phallic power, one of the dominant signifiers in the traditional Western, as a gaurantor of financial independence rather than its axiomatic meaning of sexual longevity or destructive authority. In this way, Deadwood\u27s intervention into the American Western canon is its overt insistence on historical and economic determinancy as the prime shapers of frontier ideology

Gold Is Every Man\u27s Opportunity Castration Anxiety and the Economic Venture In \u3ci\u3eDeadwood\u3c/i\u3e

In one of the most famous and quoted passages from The Eighteenth Brumaire of Louis Bonaparte, Karl Marx observes, Men make their own history, but not spontaneously, under conditions they have chosen for themselves; rather on terms immediately existing, given and handed down to them. While the historical conditions that engendered the Black Hills gold rush of the mid-1870s were more forced by and upon the participants than handed to them, Marx\u27s argument resonates loudly with the anti-romantic project of HBO\u27s critically acclaimed Western, Deadwood. Series creator David Milch makes a similar point about the town of Deadwood: The only reason the town of Deadwood exists is gold. Milch bluntly discards the Western genre\u27s foundational ideology of self-determination, considering these principles a delusion that obscures the material realities of the late nineteenth century. Were it not for the curious oscillation of history and economy, of time and theft, toward a mining free-for-all zone in the Black Hills, it seems unlikely that the war cries of noninterference and isolationism would have sounded so consistently throughout the camp of prospectors. To that end, Milch\u27s series goes to great lengths to remind viewers of the historical contingencies that underlie Deadwood\u27s dreams of separatism and self-rule. Deadwood contributes to recent revisions of the Western precisely by calling attention to the economic and historical conditions that incubated the illusory myth of selfreliant individualism in the frontier space. In part, what the series overturns is the popular and fantastical treatment of the frontier as a blank space where the rugged loner could test out his preformed codes of atomized republicanism. Or, as Richard Slotkin has put it, to promote the fabled version of the West is to turn from the tragedy of fraternal strife of labor and capital and embrace the classic quest of the republic\u27s heroic ages, the mission to bring light, law, liberty, Christianity, and commerce to the savage places of the earth. If Slotkin identifies a version of the West that is mythic representation, then certainly Deadwood is a sort of grimacing antimyth. The show foregrounds a distribution of power in the Great Plains that is gilded with gold. By focusing on the struggle of the camp and its individual inhabitants against state intervention, Deadwood forces us to consider the historical factors that placed the contested, lawless matrix of the Black Hills in conflict and eventual compliance with the nation and its capitalist harbingers. In this article, we argue that the thematic movement of Deadwood hinges on the secondseason episode Almagmation and Capital, which marks the series\u27 transition from a concern with lawlessness to a focus on the economics of western settlement and incorporation. We explore how the episode\u27s curiously abundant representations of castration contain a fundamental anxiety over national annexation and loss of economic autonomy. Ultimately, Deadwood reconfigures phallic power, one of the dominant signifiers in the traditional Western, as a gaurantor of financial independence rather than its axiomatic meaning of sexual longevity or destructive authority. In this way, Deadwood\u27s intervention into the American Western canon is its overt insistence on historical and economic determinancy as the prime shapers of frontier ideology

Particle size characterization of SCMs by mercury intrusion porosimetry

Mercury intrusion porosimetry (MIP) is widely used for the microstructural characterisation of porous solids. Comparatively few studies have employed the technique to characterise the size of particles within powdered samples. The present study uses the MIP technique to characterise the particle sizes of contemporary supplementary cementitious materials (SCMs), and in particular uses the technique to present particle size distributions, rather than a single mean size. Representivity of the technique for known limitations of non-spherical and porous particles are checked using the Scanning Electron Microscope. The findings indicate that the MIP affords a good approximation of particle sizes, including distributions, of spherical and non-spherical particles. The technique was also found to provide reasonable accuracy for estimating the particle sizes of highly porous particles, where distinction between inter-particle and intra-particle porosity was made

Challenges for Chemoinformatics Education in Drug Discovery

Surveys the curriculum developed at Indiana University for teaching cheminformatics in the IU School of Informatic