Report Of The Proceedings Of A General Meeting Of Messengers From Thirteen Congregations, 1834.

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Relation Between First Arrival Time and Permeability in Self-Affine Fractures with Areas in Contact

We demonstrate that the first arrival time in dispersive processes in self-affine fractures are governed by the same length scale characterizing the fractures as that which controls their permeability. In one-dimensional channel flow this length scale is the aperture of the bottle neck, i.e., the region having the smallest aperture. In two dimensions, the concept of a bottle neck is generalized to that of a minimal path normal to the flow. The length scale is then the average aperture along this path. There is a linear relationship between the first arrival time and this length scale, even when there is strong overlap between the fracture surfaces creating areas with zero permeability. We express the first arrival time directly in terms of the permeability.Comment: EPL (2012)

Illinois River Levees: Sizing Up Their Impact on Flooding and Risk

The Illinois River is separated from its floodplain by a series of levees constructed and modified over time. These levees are subject to overtopping, but the frequency of the critical flood event varies from levee system to system and is not generally known. Investigations to consider reconnecting the river and its floodplain, building resilient river communities, and potentially diverting floods to agricultural land all require information about the land area, land use, structures, and population of each levee protected area. The objective of this research is to provide a comprehensive description of the leveed area along the Illinois River. Using the United States Army Corps of Engineers (USACE) National Levee Database (NLD), levee systems along the Illinois River were identified based on the availability of highly detailed topographic data. Each levee system was then analyzed in conjunction with the Upper Mississippi River System Flow Frequency Study (UMRSFFS) to determine the critical flood event expected to overtop each levee system. Based on this overtopping analysis, the areas of inundation landward of each levee system were studied using flooding depth and demographic and economic analysis to produce a representative summary of the risk for each levee system. Flooding depth grids were produced for each levee system representing the extent and depth of inundation expected when a levee system first overtops. Economic analysis included both investigation of average agricultural production per levee system using United States Department of Agriculture soil and crop data, and structural risk exposure using the Federal Emergency Management Agency Hazus-MH risk analysis software. The 35 levee systems studied have an annual chance of overtopping ranging from 6.9% to less than 0.2% (or 14 to >500 years on average). The average depth of flooding for a levee system due to overtopping ranges from 5.3 feet to 24.1 feet. Across all levee systems analyzed (206,000 acres), the average depth of flooding due to overtopping was 15.4 feet. This suggests that more than 3.1 million acre-feet of floodplain storage is currently disconnected from the Illinois River by the studied levees. The average gross economic value of crops grown within the levee systems included in this analysis was approximately 130 million dollars per year (based on crop years 2010–2012). Nearly 80% of the land area within the levee systems is devoted to the production of corn and soybeans. The remainder of the land area is evenly divided (about 5% each) among developed lands, open water, and pasture/hay. The population living within the Illinois River levee systems decreased approximately 1% between 2000 and 2010 to just over 9,500. More than 90% of the studied population lives within just 3 of the 35 studied levee systems. Although diversity increased slightly between 2000 and 2010, the population remains predominately white. Nearly 60% of the population is aged 18-64 with 26% less than 18 and 14% greater than 64. Hazards analysis using the Federal Emergency Management Agency Hazus-MH utility and overtopping projections produces an estimate of total exposure to the General Building Stock (GBS). These exposure estimates range, in terms of full building replacement value, from insignificant for small agricultural levees to more than 660 million dollars in developed urban areas. Expected damages due to overtopping range from insignificant to more than 155 million dollars. The total exposure to the GBS across all studied levee systems was more than $1.1 billion. Damages to the GBS due to overtopping of all levee systems is expected to be more than 265 million dollars.National Great Rivers Research and Education Centerpublished or submitted for publicationis peer reviewedOpe

Working memory capacity does not always support future-oriented mind wandering.

To evaluate the claim that mind-wandering demands executive resources, and more specifically that people with better executive control will have the resources to engage in more future-oriented thought than will those with poorer executive control, we reanalyzed thought-report data from 2 independently conducted studies (J. C. McVay & M. J. Kane, 2012, Why does working memory capacity predict variation in reading comprehension? On the influence of mind wandering and executive attention, Journal of Experimental Psychology: General, Vol. 141, pp. 302–320; N. Unsworth & B. D. McMillan, in press, Mind-wandering and reading comprehension: Examining the roles of working memory capacity, interest, motivation, and topic experience, Journal of Experimental Psychology: Learning, Memory, and Cognition) on working memory capacity (WMC), mind-wandering, and reading comprehension. Both of these individual-differences studies assessed large samples of university subjects' WMC abilities via multiple tasks and probed their immediate thought content while reading; in reporting any task-unrelated thoughts (TUTs), subjects indicated whether those thoughts were about the future or the past, if applicable. In contrast to previously published findings indicating that higher WMC subjects mind-wandered about the future more than did lower WMC subjects (B. Baird, J. Smallwood, & J. W. Schooler, 2011, Back to the future: Autobiographical planning and the functionality of mind-wandering, Consciousness and Cognition, Vol. 20, pp. 1604–1611), we found only weak to modest negative correlations between WMC and future-oriented TUTs. If anything, our findings suggest that higher WMC subjects' TUTs were somewhat less often future-oriented than were lower WMC subjects'. Either WMC is not truly associated with mind-wandering about the future, or we have identified some important boundary conditions around that association

Drifting from slow to “D’oh!” Working memory capacity and mind wandering predict extreme reaction times and executive-control errors.

A combined experimental, individual-differences, and thought-sampling study tested the predictions of executive attention (e.g., Engle & Kane, 2004) and coordinative binding (e.g., Oberauer, Süß, Wilhelm, & Sander, 2007) theories of working memory capacity (WMC). We assessed 288 subjects' WMC and their performance and mind-wandering rates during a sustained-attention task; subjects completed either a go/no-go version requiring executive control over habit or a vigilance version that did not. We further combined the data with those from McVay and Kane (2009) to (1) gauge the contributions of WMC and attentional lapses to the worst performance rule and the tail, or t parameter, of reaction time (RT) distributions; (2) assess which parameters from a quantitative evidence-accumulation RT model were predicted by WMC and mind-wandering reports; and (3) consider intrasubject RT patterns—particularly, speeding—as potential objective markers of mind wandering. We found that WMC predicted action and thought control in only some conditions, that attentional lapses (indicated by task-unrelated-thought reports and drift-rate variability in evidence accumulation) contributed to t, performance accuracy, and WMC's association with them and that mind-wandering experiences were not predicted by trial-to-trial RT changes, and so they cannot always be inferred from objective performance measures

Why does working memory capacity predict variation in reading comprehension? On the influence of mind wandering and executive attention.

Some people are better readers than others, and this variation in comprehension ability is predicted by measures of working memory capacity (WMC). The primary goal of this study was to investigate the mediating role of mind-wandering experiences in the association between WMC and normal individual differences in reading comprehension, as predicted by the executive-attention theory of WMC (e.g., Engle & Kane, 2004). We used a latent-variable, structural-equation-model approach, testing skilled adult readers on 3 WMC span tasks, 7 varied reading-comprehension tasks, and 3 attention-control tasks. Mind wandering was assessed using experimenter-scheduled thought probes during 4 different tasks (2 reading, 2 attention-control). The results support the executive-attention theory of WMC. Mind wandering across the 4 tasks loaded onto a single latent factor, reflecting a stable individual difference. Most important, mind wandering was a significant mediator in the relationship between WMC and reading comprehension, suggesting that the WMC–comprehension correlation is driven, in part, by attention control over intruding thoughts. We discuss implications for theories of WMC, attention control, and reading comprehension