Nonlinear and quantum atom optics

Coherent matter waves in the form of Bose-Einstein condensates have led to the development of nonlinear and quantum atom optics - the de Broglie wave analogues of nonlinear and quantum optics with light. In nonlinear atom optics, four-wave mixing of matter waves and mixing of combinations of light and matter waves have been observed; such progress culminated in the demonstration of phase-coherent matter-wave amplification. Solitons represent another active area in nonlinear atom optics: these non-dispersing propagating modes of the equation that governs Bose-Einstein condensates have been created experimentally, and observed subsequently to break up into vortices. Quantum atom optics is concerned with the statistical properties and correlations of matter-wave fields. A first step in this area is the measurement of reduced number fluctuations in a Bose-Einstein condensate partitioned into a series of optical potential wells.     

Natural and unnatural; wild and cultural

Yellowstone National Parks mission and policy can be clarified by analysis of the natural and the unnatural. Nature is a comprehensive word, in some uses excluding nothing; more useful is a contrast distinguishing nature and culture . Specifying ""wild nature"" denotes spontaneous nature absent human influence. Critics claim that the meaning of wild nature, especially of wilderness, is a foil of culture. Pristine nature, often romanticized, is contrasted with a technological and industrial culture. By this account, wilderness is a social construction. Nevertheless, wild nature successfully denotes, outside culture, an evolutionary and ecological natural history, which remains present on the Yellowstone landscape, jeopardized by numerous human influences, including the invasions of exotic species. Natural processes have returned in the past, as when Native Americans left the landscape. Natural processes can be preserved today, because of, rather than in spite of, park management. Over much of the North American landscape nature is managed and at an end. Yellowstone provides an opportunity to encounter and to conserve ""untrammeled"" nature as an end in itself, past, present, and future.     

Spectrum of Aeromonas and Plesiomonas infections in patients with cancer and AIDS

The spectrum of infection with Aeromonas and Plesiomonas included gastroenteritis, bacteremia, biliary tract infection, perirectal infection, and disseminated disease. Most patients (86%) with bacteremia were neutropenic (less than 500 PMN/mm3). Colonization of stools and sputum also occurred. Therapy with aminoglycosides, beta-lactams, trimethoprim/sulfamethoxazole, and the newer quinolones was effective in patients with AIDS and cancer.     

Natural enemy assemblages on native and reseeded grasslands in southwestern Montana: a family-level analysis

We conducted a 2-year survey, using sweep sampling and family-level taxon identification, of the predatory and parasitoid insects on grassland sites in the Gallatin Valley of southwestern Montana. The 25 sites were divided into 4 habitat classes: 2 native habitat types ( Stipa comata/Bouteloua gracilis and Festuca idahoensis/Agropyron spicatum ) and 2 that had been reseeded with either crested wheatgrass ( Agropyron cristatum ) or smooth brome ( Bromus inermis ). Our major goal was to make quantitative comparisons of the abundance of insects among native and reseeded habitats. Of 51 families in 5 insect orders identified, 7 Hymenoptera (Encyrtidae, Braconidae, Ichneumonidae, Pteromalidae, Eulophidae, Scelionidae, and Torymidae), 3 Hemiptera (Lygaeidae, Nabidae, and Reduviidae), 1 Coleoptera (Coccinellidae), and 1 Diptera (Asilidae) comprised 90% of the natural enemies sampled. Ordination analyses provided no strong evidence that the 4 habitat classes contained distinct overall natural enemy communities. However, contiguous native and reseeded sites usually had relatively different overall natural enemy assemblages, suggesting that vegetation was often a more important correlate of community composition than was close spatial proximity of sites. Furthermore, several common families exhibited differential abundances across habitat classes in one or both years. For example, in 1989, Eulophidae, Pteromalidae, and Torymidae were more abundant on native Festuca/Agropyron sites, whereas Encyrtidae and Nabidae were more abundant on Festuca/Agropyron sites reseeded with Bromus inermis . Although analyses of insect assemblages classified to the family level provide somewhat limited information on functional ecological differences among habitats, they allow one to survey a broad array of taxa to identify focal groups for future conservation and land management studies.