The Rising Age Gap in Economic Well-Being

Compares changes in median net worth of households between 1984 and 2009 by age of head of household. Examines contributing factors, including the housing market bubble, the 2007-09 recession's effect on employment, and longer-term demographic trends

EXTENSION OF FLOODING DATABASE FOR LARGE DIAMETER TUBE AT VARIABLE PRESSURE INCLUDING HYSTERESIS EFFECTS

An experimental investigation into flooding phenomena was conducted to acquire data using steam/water and air/water fluid pairs at varying conditions within a large diameter vertical tube with annular flow. Experiments were performed to expand the database previously collected and verify correlations developed. Additionally, experimentation was conducted to determine hysteresis effects that may occur during flooding. Experiments were completed in a previously established vertical test section. Flooding tests were conducted by forming an annular liquid film within the test section then injecting gas into the bottom of the test section until reversal of the annular film. Tests were performed at various gas inlet flow rates with water inlet flow rates ranging from 5 to 8 gallons per minute, and pressure varying from atmospheric pressure to 45 psig. Data collected extends the range data beyond previous studies at the Nuclear Heat Transfer Systems laboratory. Data were collected in 0.5 GPM increments for the liquid mass flow rate range, filling out the data set previously collected. The additional data increases the reliability of the flooding database and flooding curves. Integration of the new data set with previous data enhances understanding of the effects of pressure, gas-liquid combination, and condensation effects of flooding phenomena. Post-processing of data produced flooding curves to compare data sets. Integration of flooding data showed that when data is plotted as dimensionless Kutateladze parameters showing that fluid-pair data overlay onto one another and a slight dependence on pressure of the system is present for steam/water data. Hysteresis data was post-processed, and hysteresis curves produced, both gasliquid systems exhibited hysteresis effects, namely as the gas flow rate was incrementally decreased, flooding occurred at a Kutateladze gas inlet parameter below that which is required to initiate flooding. The data suggests that higher carryover mass fraction can be sustained when the gas flow rate is being lowered from a flow rate beyond that needed to achieve the onset of flooding, effects were more dramatic at higher water inlet flow rates and pressures. Further, air/water mixtures showed more hysteresis than steam/water mixtures

Soil and geomorphic relationships of two water quality landscapes on the Ames Plantation

Spatial variability, parent material relationships, and geomorphic position are important factors in interpreting soil behavior. This research project was conducted to evaluate soil properties, stratigraphy, and site properties of two experimental water quality areas on the Ames Plantation. During the installation of two water quality experimental areas, twelve deep wells were established on each of the Hancock Tract area and the West Pasture Tractarea in order to monitor water in the first permanent aquifer. Six of those wells (ranging from about 10.5 to 18.25 m) were sampled using either a CME or split-spoon sampler, in order to access parent material stratigraphy. Additionally, a total of 47 shallow wells (vadose zone wells ranging from about 1.85 to 2.40 meters) were installed and soil morphology was described and recorded. Topographic maps at a scale of 1:24,000 with approximately 6 meter contour interval were used to examine the overall geomorphic positions of the sites. Standard soil survey laboratory procedures were employed on the deep well samples for particle size, cation exchange capacity and base saturation, pH, total carbon, free iron oxides, and KCl exchangeable aluminum. A modified hydrofluoric acid/aqua-regia microwave procedure and inductively coupled argon plasma emission spectrometry was used to determine total concentrations of iron, titanium, and zirconium. An order 1 soil map was made of each site using the soil descriptions taken during shallow well installation. Map units were defined by taxonomic classification and further subdivisions were made at the phased level based on slope, erosion class, and depth to the lithologic discontinuity. Laboratory data and descriptions from the deep wells were used to confirm classification. Characterized profiles were used as typical pedons for map units when possible. Evaluation of the 1:24,000 scale revealed that the two areas were located on two separate terrace levels. The West Pasture site was located on the Henderson terrace, and the Hancock Tract site was located on the Humbolt terrace as described by Saucier (1987). A sequence of loess/alluvium/tertiary sands was found in each of the six well cores. Thickness of the loess ranged from 1.43 to 3.05 meters; the mixing zone ranged from 1.37 to 1.89 meters thick; and thickness of the alluvium ranged from 2.75 to 6.76 meters. A paleosol was present in the mixing zone of the loess and alluvium in five of the cores sampled. Differences in the Peoria and Roxana loess depositions could not be determined. Stratigraphic position and morphological and chemical data suggested that the loessial material of the mixing zone paleosols was of the Loveland deposition. The paleosol had formed in the unmixed Loveland loess layer in the remaining sample core. A total of seven map units were defined which incorporated six different taxons at the subgroup level. Five of the taxons were in the fine-silty, mixed, thermic family of Alfisols; one of the map units was One of the map units was typified by fine-loamy, mixed, thermic family of Ultisols; and the other was typically in the fine-silty, mixed, thermic family of Inceptisols. Taxons at the subgroup level were Fragic Hapludalfs, Ultic Hapludalfs, Typic Fragiudalfs, Glossaquic Fragiudalfs, Typic Paleudults, and Dystric Eutrochrepts

Patching task-level robot controllers based on a local µ-calculus formula

We present a method for mending strategies for GR(1) specifications. Given the addition or removal of edges from the game graph describing a problem (essentially transition rules in a GR(1) specification), we apply a µ-calculus formula to a neighborhood of states to obtain a “local strategy” that navigates around the invalidated parts of an original synthesized strategy. Our method may thus avoid global resynthesis while recovering correctness with respect to the new specification. We illustrate the results both in simulation and on physical hardware for a planar robot surveillance task

Ecology of Juvenile Walleye Pollock, Theragra chalcogramma: Papers from the workshop "The Importance of Prerecruit Walleye Pollock to the Bering Sea and North Pacific Ecosystems" Seattle, Washington, 28-30 October 1993

The Alaska Fisheries Science Center (AFSC), National Marine Fisheries Service (NMFS), hosted an international workshop, 'The Importance of Prerecruit Walleye Pollock to the Bering Sea and North Pacific Ecosystems," from 28 to 30 October 1993. This workshop was held in conjunction with the annual International North Pacific Marine Science Organization (PICES) meeting held in Seattle. Nearly 100 representatives from government agencies, universities, and the fishing industry in Canada, Japan, the People's Republic of China, Russia, and the United States took part in the workshop to review and discuss current knowledge on juvenile pollock from the postlarval period to the time they recruit to the fisheries. In addition to its importance to humans as a major commercial species, pollock also serves as a major forage species for many marine fishes, birds, and mammals in the North Pacific region. (PDF file contains 236 pages.

Production Practices and Sample Costs for a Diversified Organic Vegetable Operation on the Central Coast of California

Organic vegetable farms on the Central Coast region of California are generally intensive operations. That is, two and sometimes three crops may be harvested off the same acreage each year. Many approaches exist for rowing and marketing organic vegetables. This publication describes the range of soil management practices, pest management, crop rotations, cover crops, and harvest and packing methods currently used by organic growers on the Central Coast of California. Marketing options and state and federal regulations governing organic commodities are also discussed. A general sequence of operations, equipment requirements, resource use, costs, yield and return ranges are presented for thirteen vegetable crops and two cover crops. The vegetables included are cabbage, cauliflower, cucumbers, garlic, lettuce (leaf and romaine), onions (red and yellow), snap peas, snow peas, bell peppers (green and red), sweet corn, and winter squash (large and small varieties). Barley and vetch are the two cover crops detailed.Crop Production/Industries,

Hot-swapping robot task goals in reactive formal synthesis

We consider the problem of synthesizing robot controllers to realize a task that unpredictably changes with time. Tasks are formally expressed in the GR(1) fragment of temporal logic, in which some of the variables are set by an adversary. The task changes by the addition or removal of goals, which occurs online (i.e., at run-time). We present an algorithm for mending control strategies to realize tasks after the addition of goals, while avoiding global re-synthesis of the strategy. Experiments are presented for a planar surveillance task in which new regions of interest are incrementally added. Run-times are empirically shown to be favorable compared to re-synthesizing from scratch. We also present an algorithm for mending control strategies for the removal of goals. While in this setting the original strategy is still feasible, our algorithm provides a more satisfying solution by "tightening loose ends.'' Both algorithms are shown to yield so-called reach annotations, and thus the control strategies are easily amenable to other algorithms concerning incremental synthesis, e.g., as in previous work by the authors for navigation in uncertain environments