Review of \u3ci\u3eVisions of Paradise: Glimpses of Our Landscape\u27s Legacy\u3c/i\u3e By John Warfield Simpson

In this book\u27s first pages, Simpson dissects its title and says his use of glimpses there indicates that this is not the complete story of the landscape. Instead, it is a set of snapshots of formative forces over the past two hundred years that ... most shaped our contemporary setting. Readily conceding that other academics provide the original scholarship he offers here, Simpson holds nonetheless that his snapshots synthesize that scholarship across many disciplinary boundaries to clarify and find general meaning in the landscape story .... Simpson is as good as his word. Visions of Paradise is a lucid and readable overview of Euro-American contact with, and thus understanding of, that portion of the North American continent that became the United States. He surveys a broad range of sources, personalizing them in ways that both add to his exposition and assert his commitment to landscape values; and in doing so he achieves the synthetic multidisciplinary synthesis he seeks. Particularly effective is his singling out of James Kilbourne, a Connecticut man who, in the first years of the nineteenth century, bought a large tract of land in central Ohio for the Scioto Company and moved to the town he helped found there, Worthington. Returning to Kilbourne periodically throughout his analysis, Simpson uses him to demonstrate that since Kilbourne\u27s day American landscape values have remained remarkably constant at their core. That is, he details the numerous ways Euro-Americans have altered the land by seeing it, like Kilbourne, as a virtually limitless source of potentially valuable natural resources. Nevertheless, there is very little beyond the contextual for the serious student of the Great Plains in Visions of Paradise. The three chapters devoted to the region\u27s exploration and settlement are, if not exactly perfunctory, then just diligent recitations of well-known analyses (DeVoto, Smith, Stegner, Webb). Simpson offers only the usual happenings, people, and places-exploration, the Oregon and Santa Fe Trails, the destruction of the buffalo, Benton and Gilpin boosterism, the cattle trade, railroads, and the failure of the Homestead Act on the Plains. Evidently, Simpson needed to get from Ohio-the history of which he clearly knows-to the Great Basin explorations of John Wesley Powell and to John Muir\u27s Yosemite. (Together with his discussion of George Perkins Marsh, the overview analyses of Powell and Muir are especially good, as is Simpson\u27s skepticism toward Transcendentalist understandings of land as natural environment.) As usual, then, the Great Plains seems here to be in the way of the main point. Even so, Simpson integrates the region appropriately within the whole of his analysis, itself one that impresses by its readability, the multidisciplinary scope of its sources, and its author\u27s evident commitment to a radical shift in American landscape values through a deeper understanding of their historical bases

Review of Images of the West: Changing Perceptions of the Prairies, 1690-1960.

Over the past several years, Western Producer Prairie Books has published volumes that demonstrate-quite apart from the materials they offer and the arguments they advancethe enduring lure of the land felt by English-Canadians (both prairie dwellers and those living elsewhere) toward their prairie as an evocative and formative landscape. Ronald Rees\u27s Land of Earth and Sky: Landscape Painting of Western Canada (1984) and New and Naked Land: Making the Prairies Home (1988), from the same press, and now R. Douglas Francis\u27s Images of the West, suggest that Western Producer is tapping a general interest in the Canadian prairie landscape as subject broader than the scholarly audience presupposed by such works as Edward A. McCourt\u27s The Canadian West in Fiction (1947; revised 1970), Laurence Ricou\u27s Vertical Man/Horizontal World (1973), Dick Harrison\u27s Unnamed Country (1977), or my own The Great Prairie Fact and Literary Imagination (1989). Indeed, while drawing upon these and other antecedents, Francis-a Canadian intellectual historian teaching at the University of Calgary-aims primarily at the general reader [rather] than for the specialist in order to examine the changing images of the West over the entire three centuries of exploration and settlement by the white man (xvii, xvi)

AGN Feedback models: Correlations with star formation and observational implications of time evolution

We examine the correlation between the star formation rate (SFR) and black hole accretion rate (BHAR) across a suite of different AGN feedback models, using the time evolution of a merger simulation. By considering three different stages of evolution, and a distinction between the nuclear and outer regions of star formation, we consider 63 different cases. Despite many of the feedback models fitting the M-\sigma\ relationship well, there are often distinct differences in the SFR-BHAR correlations, with close to linear trends only being present after the merger. Some of the models also show evolution in the SFR-BHAR parameter space that is at times directly across the long-term averaged SFR-BHAR correlation. This suggests that the observational SFR-BHAR correlation found for ensembles of galaxies is an approximate statistical trend, as suggested by Hickox et al. Decomposing the SFR into nuclear and outer components also highlights notable differences between models and there is only modest agreement with observational studies examining this in Seyfert galaxies. For the fraction of the black hole mass growth from the merger event relative to the final black hole mass, we find as much as a factor of three variation among models. This also translates into a similar variation in the post-starburst black hole mass growth. Overall, we find that while qualitative features are often similar amongst models, precise quantitative analysis shows there can be quite distinct differences.Comment: Accepted to MNRAS. Comments welcom

On the Spatial Correlations of Lyman Break Galaxies

Motivated by the observed discrepancy between the strong spatial correlations of Lyman break galaxies (LBGs) and their velocity dispersions, we consider a theoretical model in which these starbursting galaxies are associated with dark matter halos that experience appreciable infall of material. We show using numerical simulation that selecting halos that substantially increase in mass within a fixed time interval introduces a ``temporal bias'' which boosts their clustering above that of the underlying population. If time intervals consistent with the observed LBGs star formation rates of 50 solar masses per year are chosen, then spatial correlations are enhanced by up to a factor of two. These values roughly correspond to the geometrical bias of objects three times as massive. Thus, it is clear that temporal biasing must be taken into account when interpreting the properties of Lyman break galaxies.Comment: 5 Pages, 2 Figures, Accepted for Publication in ApJ Letter

New verification method for embedded systems

Journal ArticleAbstract-Verification of embedded systems is complicated by the fact that they are composed of digital hardware, analog sensors and actuators, and low level software. In order to verify the interaction of these heterogeneous components, it would be beneficial to have a single modeling formalism that is capable of representing all of these components. To address this need, this paper describes an extended labeled hybrid Petri net (LHPN) model that includes constructs for Boolean, discrete, and continuous variables as well as constructs to model timing. This paper also presents a method to verify these extended LHPNs. Finally, this paper presents a case study to illustrate the application of this model to the verification of a fault-tolerant temperature sensor

The Contribution of E2F-Regulated Transcription to Drosophila PCNA Gene Function

E2F proteins control cell cycle progression by predominantly acting as either activators or repressors of transcription [1]. How the antagonizing activities of different E2Fs are integrated by cis-acting control regions into a final transcriptional output in an intact animal is not well understood. E2F function is required for normal development in many species [2–7], but it is not completely clear for which genes E2F-regulated transcription provides an essential biological function. To address these questions, we have characterized the control region of the Drosophila PCNA gene. A single E2F binding site within a 100-bp enhancer is necessary and sufficient to direct the correct spatiotemporal program of G1-S-regulated PCNA expression during development. This dynamic program requires both E2F-mediated transcriptional activation and repression, which, in Drosophila, are thought to be carried out by two distinct E2F proteins [2, 3, 8–11]. Our data suggest that functional antagonism between these different E2F proteins can occur in vivo by competition for the same binding site. An engineered PCNA gene with mutated E2F binding sites supports a low level of expression that can partially rescue the lethality of PCNA null mutants. Thus, E2F regulation of PCNA is dispensable for viability, but is nonetheless important for normal Drosophila development

Cross-Presentation of Cell-Associated Antigens by Mouse Splenic Dendritic Cell Populations

Cross-presentation of cell-associated antigens (Ag) plays an important role in the induction of anti-tumor responses, autoimmune diseases, and transplant rejection. While several dendritic cell (DC) populations can induce pro-inflammatory CD8+ T cell responses to cell-associated Ag during infection, in the absence of infection, cross-priming of naïve CD8+ T cells is highly restricted. Comparison of the main splenic DC populations in mice – including the classic, cross-presenting CD8α DC and the recently described merocytic DC (mcDC) – reveals that cross-priming DCs display a distinct phenotype in cell-associated Ag uptake, endosomal/lysosomal trafficking, lysosomal acidification, and Ag persistence compared to non-cross-priming DC populations. Although the CD8α DC and mcDC subsets utilize similar processing pathways to cross-present cell-associated Ag, cross-priming by CD8α DCs is associated with IL-12 production, while the superior priming of the mcDC is critically dependent on type I IFN production. This discussion illustrates how subtle differences in internal processing pathways and their signaling sequelae significantly affect the duration of Ag cross-presentation and cytokine production by DCs, thereby shaping the ensuing CD8+ T cell response