Fishes and zooplankton were obtained (March-April 1979 and partly in August 1974) from 45 hauls taken during the day and at night in the central equatorial Atlantic between Latitude 3 ~ and 2 ~ from the surface to 1 250-m depth, using the RMT 1+8, a combined opening-closing plankton and micronekton trawl. The vertical distribution of 30 myctophid species is described.All species migrate in a diel pattern, Ceratoscopelus warmingii and Lampanyctus photonotus down to at least 1 250 m. During daytime most species aggregated at 400-to 700-m depth, therefore only partly occupying the depth of the Deep Scattering Layer (400 to 500 m at 15 kHz). The feeding patterns of seven of the most abundant species were compared, with a total of 1 905 stomach contents being analysed. All seven species are regarded as opportunistic predators, which feed predominantly during the night on calanoid copepods. A total of 66 species of calanoid copepods were identified among the prey items, with smaller species definitely being in the minority.Stomachs of C. warmingii (700 to 1 250 m depth) and Lepidophanes guentheri (500 to 900 m depth) from daytime samples contained copepod species restricted to the upper 150 m of the water column, including Undinula vulgaris, Nannocalanus minor, and Euchaeta marina, thereby confirming an extended vertical migration of predators. Differences in diet and preferences between species in their total food spectrum are described.
Formulas and charts are given which aid the design of right circular cylinder cavity resonators operating in the TE O1n mode, which yields the highest Q for a given volume. The application of these to the design of an echo boll:radar test set is shown, and practical considerations arising in the construction of a tunable cavity are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.