Effects of orbital exposure on Halar during the LDEF mission

Thermomechanical Analysis (TMA), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA) were performed on samples of Halar exposed on the LDEF Mission for 6 years in orbit and unexposed Halar control samples. Sections 10-100 microns thick were removed from the exposed surface down to a depth of 1,000 microns through the 3 mm thick samples. The TMA and DSC results, which arise from the entire slice and not just its surface, showed no differences between the LDEF and the control samples. TMA scans were run from ambient to 300 C; results were compared by a tabulation of the glass transition temperatures. DSC scans were run from ambient to 700 C; the enthalpy of melting was compared for the samples as a function of section depth with the sample. The TGA results, which arise from the surface of the sample initially, showed a sharp increase in the topmost 50 micron section (the exposed, discolored side) in the weight loss of 170 C in oxygen. This weight loss dropped to bulk values in the range of depth of 50-200 microns. The control sample showed only a slight increase in weight loss as the top surface was approached. The LDEF Halar sample appears to be mechanically undamaged, with a surface layer which oxidizes faster as a result of orbital exposure

Transparency, expectations, and forecasts

In 1994, the Federal Open Market Committee (FOMC) began to release statements after each meeting. This paper investigates whether the public’s views about the current path of the economy and of future policy have been affected by changes in the Federal Reserve’s communications policy as reflected in private sector’s forecasts of future economic conditions and policy moves. In particular, has the ability of private agents to predict where the economy is going improved since 1994? If so, on which dimensions has the ability to forecast improved? We find evidence that the individuals’ forecasts have been more synchronized since 1994, implying the possible effects of the FOMC’s transparency. On the other hand, we find little evidence that the common forecast errors, which are the driving force of overall forecast errors, have become smaller since 1994.

Laboratory Rearing of \u3ci\u3eLycaeides Melissa Samuelis\u3c/i\u3e (Lepidoptera: Lycaenidae), An Endangered Butterfly in Michigan

The Karner blue butterfly (Lycaeides melissa samuelis) is listed as a federally endangered species in the United States. It occurs in oak savanna and pine barren habitats from eastern Minnesota to New Hampshire. In 1994, we successfully reared Karner blue larvae under controlled laboratory conditions for experimental purposes, and report on those rearing methods here. We collected 20 female Karner blue adults of the spring generation from two areas in Michigan, and housed them in cages in an environmental chamber at 240 -26°C for 5 days. The female butterflies produced 154 eggs, of which 72 hatched in an average of 4.5 days, and 68 first instars survived. Eggs, larvae and pupae were kept in a growth chamber at 24°C. Developmental time from egg to adult averaged 26 days; the average duration of each instar ranged from 3 to 4 days, and the average pupal duration was 8 days. Thirty three lab- oratory-reared Karner blue larvae successfully completed the 4 instars, and were released as adults into maternal collection sites. Laboratory rearing may be a viable means of providing Karner blue individuals for reintroduction into areas where the species is extirpated, for supplementation of small populations, or for research. Ultimately, such methods may become an integral part in the recovery of this and other rare invertebrate species

Exploratory Survey for the Emerald Ash Borer, \u3ci\u3eAgrilus Planipennis\u3c/i\u3e (Coleoptera: Buprestidae), and Its Natural Enemies in China

An exploratory survey for the emerald ash borer, Agrilus planipennis, and its natural enemies was conducted in China during October and November 2003. We examined 29 field plots in six provinces. We visually inspected living Fraxinus chinensis, F. mandshurica, F. pennsylvanica, F. rhynchophylla, and F. velutina then peeled off the bark in search of A. planipennis and associated natural enemies. We found active A. planipennis infestations in nine of the 29 field plots, including plots in the provinces of Hebei, Heilongjiang, Jilin, Liaoning, and the provincial level city of Tianjin. Signs of past A. planipennis infestations were found in five of the 20 plots where no active infestations were present. The distribution of A. planipennis was patchy within the forest, and larval densities varied greatly among trees and at different heights within the same tree. Agrilus planipennis densities ranged from 0 to 284 larvae/m2 of bark surface for 1-m log sections. The Nearctic ash species, F. pennsylvanica and F. velutina, planted in China were apparently more susceptible to A. planipennis attack than were the native Chinese ash species. Similarly, ash trees growing along streets or in plantations or city parks were more susceptible to A. planipennis infestation compared with trees in natural forests. We identified two species of natural enemies attacking A. planipennis during this survey. In Changchun City, Jilin Province and Guangang District, Tianjin City, we found a previously reported but undescribed species of Spathius sp. (Braconidae) parasitizing an average of 6.3% A. planipennis larvae in individual trees, ranging from 0 to 50%. In Changchun City, Jilin Province and in Benxi County, Liaoning Province, we discovered a previously unknown gregarious endoparasitoid of A. planipennis larvae, Tetrastichus nov. sp. (Eulophidae), with a total parasitism rate of 6.6% in individual trees, ranging from 0 to 50%. We discussed the potential role of natural enemies in the management of A. planipennis in North America

Status of the profession

The number of astronomers has grown by about 40 percent over the past decade. The number of astronomers with jobs in industry, or with long-term, non-tenured, jobs has increased dramatically compared with traditional faculty positions. The increase in the number of astronomers and the declining share of the NSF budget going to astronomy has led to extreme difficulties in the NSF grant program and in support of the National Observatories. In 1989, direct NASA support of astronomers through the grants program exceeds that of NSF, although the total of the NSF grants program over decade far exceeds that of NASA. Access to major new telescopes will be important issue for the 1990s. US astronomers, who once had a monopoly on telescopes larger than 3 meters, will, by the year 2000, have access to just half of the world's optical telescope area

Planned coal mine subsidence in Illinois: A public information booklet

Illinois Department of Commerce and Economic Opportunity, Office of Coal DevelopmentOpe