Strategic argument mapping

Includes bibliographical references (p. 38)

Spectrographic analysis of bismuth-tin eutectic alloys by spark-ignited low-voltage ac-arc excitation

Spectrographic method determines individual stainless steel components in molten bismuth-42 w/o tin eutectic to determine the solubility of Type 304 stainless steels. It utilizes the high sensitivity and precision of the spark-ignited, low-voltage ac-arc excitation of samples rendered homogeneous by dissolution

A Surprise Occurrence in Acoustic Bottom Backscatter Measurements Conducted in the Eastern Bering Sea

Acoustic backscatter measurements at different frequencies were made in the eastern Bering Sea in August 2006 from the NOAA Ship Fairweather. The measurements consisted of approximately 2,250 nm of trackline acoustic backscatter data from a 100 kHz RESON model 8111; 2,250 nm of trackline acoustic backscatter data from a 40 kHz Reson model 8160; 750 nm of trackline acoustic backscatter data from a 455 kHz Klein model 5410; and 750 nm of trackline acoustic backscatter data from a 180 kHz pre-production Klein model 7180. The two Klein systems were each towed SW-NE once along the same specified 750 nm of tracklines. The two RESON systems were each operated twice SW-NE and once NE-SW along the same tracklines as the Klein systems. The acoustic backscatter was typically what might be expected from a flat, featureless expanse of fine grained sediments. However, there was a chance encounter with an embedded community of gastropods that was documented both with bottom grab samples and video footage of the seabed. The presence of the embedded community of gastropods drastically changed the level and angle dependence of the backscatter. This paper presents a comparative analysis of the backscatter properties of the gastropod community that were observed at 40 kHz, 100 kHz, 180 kHz and 455 kHz

Comparison of epifluorescent viable bacterial count methods

Two methods, the 2-(4-Iodophenyl) 3-(4-nitrophenyl) 5-phenyltetrazolium chloride (INT) method and the direct viable count (DVC), were tested and compared for their efficiency for the determination of the viability of bacterial populations. Use of the INT method results in the formation of a dark spot within each respiring cell. The DVC method results in elongation or swelling of growing cells that are rendered incapable of cell division. Although both methods are subjective and can result in false positive results, the DVC method is best suited to analysis of waters in which the number of different types of organisms present in the same sample is assumed to be small, such as processed waters. The advantages and disadvantages of each method are discussed

Will You Miss Me When I Am Gone? The Economic Consequences of Absent Parents

This paper examines the effects of family structure on the economic resources available to children, using family fixed-effects to control for unobservable characteristics of the family. The effects of divorce on the income and consumption of children born to two-parent households, and the effects of marriage on children born into single-parent households are both considered. In the long-run (six or more years after the most recent divorce) family income falls by 40 to 45% after divorce, and food consumption is reduced by 17%. Six or more years after the most recent marriage, income of children born to single parents rises by 50 to 57%, but there is no statistically significant increase in food consumption. These estimates are substantially less than the difference in income implied by cross-sectional comparisons of different family types. When income changes are measured according to time since the parents first divorce, there is substantial recovery in income, virtually all of which is explained by subsequent remarriages. Similarly, when we look at income several years after a parent's first marriage, the gain is 28 to 33%, reflecting the short-lived nature of many of these marriages.

Does Human Capital Transfer from Parent to Child? The Intergenerational Effects of Compulsory Schooling

The strong correlation between parents' economic status and that of their children has been well-documented, but little is known about the extent to which this is a causal phenomenon. This paper attempts to improve our understanding of the causal processes that contribute to intergenerational immobility by exploiting historical changes in compulsory schooling laws that affected the educational attainment of parents without affecting their innate abilities or endowments. We examine the influence of parental compulsory schooling on grade retention status for children aged 7 to 15 using the 1960, 1970 and 1980 U.S. Censuses. Our estimates indicate that a one-year increase in the education of either parent reduces the probability that a child repeats a grade by between two and seven percentage points. Among 15 to 16 year olds living at home, we also estimate that parental compulsory schooling significantly lowers the likelihood of dropping out. These findings suggest that education policies may be able to reduce part of the intergenerational transmission of inequality.

Effect of plant growth regulators and other selected compounds on the growth of Acremonium coenophialum in vitro

A mutualistic relationship exists between the endophyte Acremonium coenophialum (Morgan, Jones and Gams) and tall fescue Festuca arundenacea (Shreb). The host, tall fescue, provides protection, a source of nutrients and a means of dissemination for the endophyte. The endophyte protects tall fescue from adverse environmental conditions, overgrazing by herbivores and insect and pathogen attack. Changes in the physiology of the fescue plant causes changes to occur in the growth of the endophyte. The purpose of this study was to examine plant growth regulators and carbohydrates to determine their effect on the growth of the endophyte. In liquid and solid media, the synthetic auxins 2,4-D (2,4-dichloro Phenoxyacetic acid) and dicamba (3,6-dichloro 2- methoxybenzoic acid), had no observable effect on growth of A. coenophialum. Abscisic acid also had no observable effect on growth of the endophyte. When A. coenophialum was exposed to an ethylene atmosphere of 9ppm, no observable difference in growth was observed when compared with the control. Gibberellic acid (GA3) had no observable effect on growth of the endophyte after 4 weeks. However, at 6 weeks, a reduction of 40 percent was observed on solid media. In liquid M102 media (Bacon et al. 1988) , growth was consistent with that of the control at concentrations of 0.1, 1 and 10μM; however, 100 percent reduction was observed at 100 μM. The synthetic cytokinin, kinetin, reduced the growth of A. coenophialum at each concentration examined. Growth reductions ranged from 20 percent at 20 μM to 100 percent at 100 μM. Zeatin also reduced the growth of the endophyte. A 50 percent growth reduction was observed at 100 μM. In liquid M102 media, no reduction in growth of the endophyte occurred at 0.1, 1, and 10 μM kinetin, but at 100 μM kinetin, growth was reduced by 95 percent. Growth of A. coenophialum on media containing various carbon sources was investigated. Radial growth was higher on sucrose than on other carbon sources tested. A morphological change was noted on media containing sucrose. The endophyte grown on media containing sucrose exhibited a mucoid-like appearance, while the endophyte grown on the xylose-substituted media had a cottony appearance. In summary, none of the plant growth regulators (PGRs) examined had a stimulatory effect on the endophyte. However, a reduction in growth was noted with cytokinins and GA3. Sucrose was a better carbon source than xylose, but changes in the morphology of the endophyte occurred when grown on media supplemented with sucrose in M102 media. The endophyte took on a mucoid-like appearance when grown on M102 media supplemented with sucrose, while cultures grown on M102 media supplemented with xylose had a white cottony appearance

Isolation as a Seismic Design Strategy for Bridges in the New Madrid Seismic Zone

The seismic hazard in the New Madrid Seismic Zone (NMSZ) is primarily from the New Madrid Fault System (NMFS), which produced a series of large earthquakes in 1811-1812. Estimates of the magnitude of these earthquakes and the event magnitude appropriate for structural design in the New Madrid Seismic Zone vary greatly and have been the subject of much debate. Current bridge design practice in the region relies primarily upon controlled damage by plastic hinging in columns/piles at piers to prevent collapse. Abutments are typically modeled with linear springs to represent piles and backfill stiffness. The usefulness, after a major seismic event, of structures designed by this method lies in doubt due to the potential for high residual displacements. Isolation has been selected as a viable design alternative for major structures since the 1970’s at least. The application of isolation to bridges in the New Madrid Seismic Zone has been limited, with the most notable example Interstate 40 over the Mississippi River (the Hernando Desoto Bridge). This was a retrofit project incorporating both Lead-Rubber Bearings (LRB) and Friction Pendulum System (FPS) bearings as isolators. The feasibility of isolation as a design strategy for bridges in the New Madrid Seismic Zone is evaluated using non-linear response history analysis. Acceleration time histories from actual events are selected, modified, and used for the analysis. Synthetic motions are generated for target design spectra and used for analysis as well. Various options for target spectra are discussed. Currently implemented simplified procedures are evaluated. Alternative, direct displacement based design procedures are explored. Various bridge types commonly to the region are discussed. Bridge types selected for study include four pile bent bridges as well as 2 and 3-span grade crossings with multi-post, reinforced concrete bents supported on friction pile caps. Isolation is proposed as an alternative which should be considered taking into account all factors, including economy. The proposition is made that isolation may be both effective and economical for certain bridges in the New Madrid Seismic Zone. To this end, the economic benefits which could potentially offset the cost of isolation bearings are explored