Formation of ions and radicals from icy grains in comets

Ion and radical formation in comets are thought to occur primarily by photodissociation of gas phase molecules. Experimental evidence and theoretical calculations are presented that show that some of the radical and ions can come directly from ice grains. The experimental evidence suggest that if the frozen molecules on the surface of grains undergo direct dissociation then they may be able to release radicals directly in the gas phase. If the molecules undergo predissociation it is unlikely that they will release radicals in the gas phase since they should be quenched. Calculations of this direct photodissociation mechanism further indicate that even if the parent molecule undergoes direct dissociation, the yield will not be high enough to explain the rays structure in comets unless the radicals are stored in the grains and then released when the grain evaporates. Calculations were also performed to determine the maximum number of ions that can be stored in an icy grain's radius. This number is compared with the ratio of the ion to neutral molecular density. The comparison suggests that some of the ions observed near the nucleus of the comet could have originally been present in the cometary nucleus. It is also pointed out that the presence of these ions in icy grains could lead to radical formation via electron recombination. Finally, an avalanche process was evaluated as another means of producing ions in comets

The Work and Play Structures of Narrative

The purpose of this essay is to point out the diversity in post-Proppian plot analysis—and, more specifically, to argue that within it one can discern two fundamentally different conceptions of narrative structure. These are not merely different theoretical grids superimposed upon the same phenomena, but represent, in fact, two objectively different types of narrative structure. These two types will be referred to as dramatic structure and instrumental structure, and they may be succinctly characterized by the antonyms 'play' and 'work' respectively. It will be argued that there is a basis in Propp for both conceptions of narrative structure and that Bremond and Greimas, in their efforts to 'generalize' Propp, have each only isolated one of two tendencies coexisting in his analytic approach. Our point of departure will be Propp's concept of the basic unit of plot structure, which he terms the function. This is a complex term. Two senses are distinguished, biological and mathematical-logical

The elements of economic development

More communities have come to realize that change is inevitable and they are establishing economic development programs to help them manage that change. At a time when the industrial revolution has given way to the information age, a good economic development program will help a community remain "tuned in" to the world. It can help business and industry to be more productive and also contribute to the community's overall viability. Accomplishing this takes a program that is broad-based and long-term.New 6/92/5M

Inhibiting protein clearance to induce cell death in tuberous sclerosis and pancreatic cancer

Indiana University-Purdue University Indianapolis (IUPUI)Sequestration at the aggresome and degradation through autophagy are two approaches by which a cell can counteract the toxic effect of misfolded proteins. Tuberous sclerosis (TS) and cancer cells can become dependent on autophagy for survival due to the high demand for protein synthesis, thus making protein clearance a potential therapeutic target. Because of its histone deacetylase (HDAC) inhibitory activity, we hypothesized that 4-phenylbutyrate (4-PBA) inhibits HDAC6 and aggresome formation to induce TS cell death. We found that 4-PBA treatment increases cell death and reduces bortezomib-induced aggresome formation. To link these results with HDAC inhibition we used two other HDAC inhibitors, trichostatin A (TSA) and tubastatin, and found that they also reduce bortezomib-induced protein aggregation. Because tubulin is a target of HDAC6, we next measured the effect of the HDAC inhibitors and 4-PBA treatment on tubulin acetylation. As expected, tubastatin increased tubulin acetylation but surprisingly TSA and 4-PBA did not. Because 4-PBA did not significantly inhibit HDAC6, we next hypothesized that 4-PBA was alternatively inducing autophagy and increasing aggresome clearance. Surprisingly, autophagy inhibition did not prevent the 4-PBA-induced reduction in protein aggregation. In conclusion, we found 4-PBA to induce cell death and reduce aggresome levels in TS cells, but we found no link between these phenomena. We next hypothesized that loss of the Ral guanine nucleotide exchange factor Rgl2 induces cell death via autophagy inhibition in pancreatic adenocarcinoma (PDAC) cells. KRas is mutationally activated in over 90% of PDACs and directly activates Rgl2. Rgl2 activates RalB, a known regulator of autophagy, and Rgl2 has been shown to promote PDAC cell survival. We first confirmed that loss of Rgl2 does increase cell death in PDAC cells. Initial experiments using doubly tagged fluorescent p62 and LC3 (autophagy markers) suggested that loss of Rgl2 inhibited autophagosome accumulation, but after developing a more sophisticated quantitation method we found loss of Rgl2 to have no effect. We also measured endogenous LC3 levels, and these experiments confirmed loss of Rgl2 to have no effect on autophagy levels. Therefore, loss of Rgl2 increases cell death in PDAC cells, but does not have a significant effect on autophagy

Descriptive Study of Assessment Centers for the Selection and Development of Secondary-school Administrators

This descriptive study is concerned with the documentation and analysis of the application of assessment center methodology for the selection and development of building-level administrators in school districts in central Kansas and northeastern Oklahoma. The primary objective is to obtain information concerning the current status of assessment center methodology in Kansas and Oklahoma so that other universities or colleges considering operating an assessment center to serve their school districts can see why, when, and how this methodology is being used.Occupational and Adult Educatio

Big Sur Visitor Characteristics and Wildland Fire Recreational Constraints

A study conducted with visitors to the Big Sur region of California during summer 2002 is presented. An onsite survey was administered to visitors to the U.S. Forest Service and California State Parks day-use and overnight facilities. Recreational constraints owing to wildland fire and fire management are detailed along with the effects of activity type, visitor demographics and other characteristics, and views of these constraints. Differences primarily exist in views of constraints related to regulations

Recreation and Fire Management in Urban National Forests: A Study of Manager Perspectives

The purpose of this study was to understand U.S. Department of Agriculture Forest Service public land managers’ perceptions of fire management and recreational use in urban national forests of the United States. An online survey was used to understand managers’ perceptions of (a) the degree to which the presence of recreational activities and experiences are a constraint to fire management, (b) the degree to which fire management and suppression activities influence the quality of a visit to a recreation site, and (c) the relationships between fire management and recreation constraints. In all, 62 district rangers within urban national forests were asked to complete an online survey, and 33 responded (53 percent). The following items were thought to moderately to severely impact the managers’ ability to manage fire: increased urban development, budget constraints, accumulation of burnable fuels, effect of smoke on visitors, increased visitation, and the lack of trained personnel. In addition, most managers believed that recreational use of day-use areas, trails, campgrounds, and access roads conflicted moderately or slightly with fire management decisions. Over 70 percent of respondents indicated that mountain bikes on unauthorized trails, vandalism, litter, encroachment from surrounding farmland, unauthorized grazing, and, unauthorized logging did not have an impact on fire management decisions. Generally respondents did not perceive management factors as limiting visitors’ pursuit of recreation activities. In addition, most managers identified the occurrence of various management activities (e.g., campground closures from smoke, trail closures owing to wildland fires, fire suppression, etc.) as slightly to not limiting at all