Propulsion technology challenges for turn-of-the-century commercial aircraft

This paper highlights the efforts being performed or sponsored by NASA, in cooperation with the U.S. civil aviation industry, to address the propulsion system technological challenges that must be met in order to ensure a viable future for the industry. Both the subsonic and supersonic aeropropulsion programs are considered. Subsonic transport propulsion program elements, including ultra-high-bypass-ratio turbofans with attendant noise reduction efforts, high-efficiency cores, and combustor emissions reductions are discussed in terms of goals, technical issues, and problem solutions. Similarly, the high-speed research propulsion efforts addressing a high-speed commercial transport are reviewed in terms of environmental barrier issues, such as oxides of nitrogen and noise reduction, and the related economic issues

Market Response to a Food Safety Shock: The 2006 Foodborne Illness Outbreak of E. coli O157:H7 Linked to Spinach

In 2006 FDA announced that consumers should not eat fresh spinach in the wake of a large foodborne illness outbreak of E. coli O157:H7. This paper investigates response of consumers to the announcement. We use an AIDS demand model with 5 food safety shock variables and retail scanner data to analyze market response. Even fifteen months after the outbreak, predicted sales of spinach in bags were still down 10 percent from what they would have been in the absense of the food safety shock. After the outbreak, consumers shifted to other leafy greens such as bulk iceberg lettuce, other bulk lettuce, and bagged salads without spinach.Food Consumption/Nutrition/Food Safety,

Food Safety and Spinach Demand: A Generalized Error Correction Model

We estimate an error correction model representing demand for leafy green vegetables but generalize the structure to allow for adjustment to one conspicuous shock. We investigate whether the adjustment rate to the U.S. Food and Drug Administration’s (FDA) 2006 warning that fresh spinach was contaminated with deadly bacteria was distinct from the overall adjustment rate. Our model allows consumers to correct both for past errors and for any errors in their reaction to the shock. This method yields an estimate of the adjustment rate to the policy shock and points to an improved estimate of the duration of policy impacts.error correction model, adjustment rates, AIDS demand model, retail food demand, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety, Health Economics and Policy,

Automated extraction of absorption features from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and Geophysical and Environmental Research Imaging Spectrometer (GERIS) data

Automated techniques were developed for the extraction and characterization of absorption features from reflectance spectra. The absorption feature extraction algorithms were successfully tested on laboratory, field, and aircraft imaging spectrometer data. A suite of laboratory spectra of the most common minerals was analyzed and absorption band characteristics tabulated. A prototype expert system was designed, implemented, and successfully tested to allow identification of minerals based on the extracted absorption band characteristics. AVIRIS spectra for a site in the northern Grapevine Mountains, Nevada, have been characterized and the minerals sericite (fine grained muscovite) and dolomite were identified. The minerals kaolinite, alunite, and buddingtonite were identified and mapped for a site at Cuprite, Nevada, using the feature extraction algorithms on the new Geophysical and Environmental Research 64 channel imaging spectrometer (GERIS) data. The feature extraction routines (written in FORTRAN and C) were interfaced to the expert system (written in PROLOG) to allow both efficient processing of numerical data and logical spectrum analysis

The Timing of Deformation in the Four Peaks Area, central Arizona, and relevance for the Mazatzal Orogeny

The Mazatzal orogeny (1.66-1.60 Ga) is a key element of the tectonic evolution of the North American continent during the Proterozoic (Whitmeyer and Karlstrom, 2007). Recently, Mesoproterozoic detrital zircon grains (1.55-1.45 Ga) have been found in metasedimentary rocks that were thought to have been deformed during the Paleoproterozoic Mazatzal orogeny (Jones et al. 2011; Doe et al. 2012, 2013; Daniel et al. 2013). Some type examples Mazatzal deformation now seem to be too young to have been deformed in the accepted time of that orogeny (1.66-1.60 Ga) and may have been deformed in the younger, newly defined, Picuris orogeny. This leads to questions regarding the timing and nature of the Mazatzal orogeny and its importance in the evolution of the North American continent. The object of this research is to constrain the timing of deformation related to the Mazatzal and Picuris orogenies and clarify the Proterozoic history of the North American continent. The Four Peaks area in central Arizona has been selected as an ideal location to tightly constrain the timing of deformation. The area hosts a package of Proterozoic metasedimentary rocks that are folded into a kilometer-scale syncline, surrounded by vi Mesoproterozoic to Paleoproterozoic granitoids. The Four Peaks syncline has been considered a type example of Mazatzal-age deformation (Karlstrom and Bowring, 1988). Zircon and monazite geochronology are presented along with structural and petrologic data in order to understand the geologic history of the Four Peaks area. The evidence suggests that three deformation events occurred at ~1675 Ma, 1665-1655 Ma and 1490-1450 Ma. Sedimentary deposition occurred 1665-1655 Ma and 1520-1490 Ma with a significant disconformity in between these episodes. Both the Mazatzal and Picuris orogenies can be associated with periods of deformation, sedimentary deposition and pluton emplacement. The most significant shortening event, which formed the Four Peaks syncline, occurred during Mesoproterozoic time and was related to the Picuris orogeny