U.S. SECTION 301 INVESTIGATION OF CANADIAN WHEAT TRADING PRACTICES

Crop Production/Industries, International Relations/Trade,

The Legacy of the Hawaiian Cultivator in Windward Valleys of Hawaii. (Volumes I and II).

The composition of a forest of relicts of cultivation in four uninhabited valleys in Kohala, Hawaii, is documented. A general hypothesis is made that arboreal distribution patterns are a function of both historical land use and ecological interaction since abandonment. The physical and historical geography of the valleys was investigated. Climate varies little, but distinct geomorphic zones offer differing biological environments. Prehistoric land use consisted of taro patches with intercropped banks. Talus slope gardens supported the Polynesian tree crops \u27ohi\u27a \u27ai (Eugenia malaccensis), kukui (Aleurites moluccana), \u27ulu, (Artocarpus incisus), ti (Cordyline terminalis), and noni (Morinda citrifolia), important in today\u27s flora. Gathering took place on slopes. Western contact with Hawaii, initiated in 1778, brought new crops. Papaya (Carica papaya), mango (Mangifera indica), guava (Psidium guajava), and coffee (Coffea arabica) were important adoptions in Kohala. As land use changed, the region also suffered depopulation, losing half its numbers between 1830 and 1870. Chinese rice-growing forestalled complete abandonment, which finally occurred after 1920. Current vegetation was assessed by creating 15 sampling units containing 554 quadrats. Inside quadrats, the size-class and species of each tree was recorded, yielding measures of frequency, density, cover, importance, and richness. Four environmental conditions were also assessed. The resulting variables were mapped and inter-correlated. Guava, kukui, noni, \u27ohi\u27a \u27ai, ti, hala (Pandanus odoratissimus), and coffee proved the most numerous species. Rarer species were often localized, illuminating historical land use. The data were examined and reformatted into matrices suitable for cross-classification analysis. Consistent relationships included the association of guava with low-slope and \u27ohi\u27a \u27ai with high-slope. Richness showed association with high-slope and cliff proximity. The mark of Hawaiian cultivators is apparent. Polynesian species accounted for 48.2% of the importance value. Size-class histograms revealed a stable structure for most species. Certain Western exotics had spotty distributions or size-class structures that indicate impending extinction. Native species are rare except for hala. There are indications that they were probably scarce during prehistory as well. This study exemplifies historical biogeography. It synthesizes methods of geography, ecology, and archaeology for the purpose of better interpreting cultural vegetation

Construction and characterization of a small-bore electrospray ionization source

AbstractA simple, economical, and efficient electrospray ionization (ESI) source has been constructed in the configuration of a probe that makes use of a standard 13 mm vacuum lock. The principal components have been placed inside a glass tube making use of the electrical insulating properties of the glass while allowing for visual adjustments to be readily made. The ESI source, a variation of an atmospheric pressure ionization interface, is a modified version of designs published by Chait et al. (Rapid Comm. Mass Spectrom.1990, 4, 81–87) and Knapp et al. (Anal. Chem.1991, 63, 1658–1660) wherein a heated metal capillary is used for desolvation. The ESI probe has been tested on three different Extrel quadrupole mass spectrometers, with removable ion volumes, using polypeptides and small proteins. No modifications to the standard electron ionization/chemical ionization lens assembly were required to obtain excellent results other than removal of the ion volume. The spectra acquired were in excellent agreement with those previously published

High performance composites research at NASA-Langley

Barriers to the more extensive use of advanced composites in heavily loaded structures on commercial transports are discussed from a materials viewpoint. NASA-Langley matrix development activities designed to overcome these barriers are presented. These include the synthesis of processible, tough, durable matrices, the development of resin property/composite property relationships which help guide the synthesis program, and the exploitation of new processing technology to effectively combine reinforcement filament with polymer matrices. Examples of five classes of polymers being investigated as matrix resins at NASA Langley are presented, including amorphous and semicrystalline thermoplastics, lightly crosslinked thermoplastics, semi-interpenetrating networks and toughened thermosets. Relationships between neat resin modulus, resin fracture energy, interlaminar fracture energy, composite compression strength, and post-impact compression strength are shown. Powder and slurry processing techniques are discussed

Preparing composite materials from matrices of processable aromatic polyimide thermoplastic blends

Composite materials with matrices of tough, thermoplastic aromatic polyimides are obtained by blending semi-crystalline polyimide powders with polyamic acid solutions to form slurries, which are used in turn to prepare prepregs, the consolidation of which into finished composites is characterized by excellent melt flow during processing

Polyimide Matrix composites: Polyimidesulfone/LARC-TPI (1:1) blend

Polyimide matrix composites were fabricated from unidirectional unsized AS-4 carbon fiber and a doped 1:1 blend of two polyimides: benzophenone dianhydride-3,3'-diamino diphenylsulfone (PISO2) and benzophenone dianhydride-3,3'-diamino benzophenone (LARC-TPI). To enhance melt flow properties, the molecular weight of the PISO2 was controlled by end-capping with phthalic anhydride and addition of 5 percent by weight p-phenylene diamine-phthalic anhydride bisamic acid dopant. Prepreg was drum-wound using a diglyme slurry comprised of the soluble polyamideacid of PISO2, the soluble bisamideacid of the dopant, and the insoluble imidized LARC-TPI powder. Melt flow studies with a rotary rheometer and parallel plate plastometer on neat resin and prepreg helped develop an optimum cure cycle. Composite mechanical properties at room and elevated temperatures, dry and moisture-saturated, were evaluated, including short beam shear strength and flexure, tensile, shear, and compression properties. Two 18 in. x 24 in. skin-stringer panels were fabricated, one of which was tested in compression to failure

Are Neural Language Models Good Plagiarists? A Benchmark for Neural Paraphrase Detection

The rise of language models such as BERT allows for high-quality text paraphrasing. This is a problem to academic integrity, as it is difficult to differentiate between original and machine-generated content. We propose a benchmark consisting of paraphrased articles using recent language models relying on the Transformer architecture. Our contribution fosters future research of paraphrase detection systems as it offers a large collection of aligned original and paraphrased documents, a study regarding its structure, classification experiments with state-of-the-art systems, and we make our findings publicly available