Land use, associated eel production, and abundance of fish and crayfish in streams in Waikato, New Zealand

The density and biomass of fish and crayfish, and the production of eels, was compared among streams in native forest, exotic forest, and pasture. Populations were estimated by multiple-pass electroshocking at 11 sites in hill-country streams in the Waikato region, North Island. Three sites were in native forest, four in exotic forest, and four in pasture. Length of stream sampled at each site was 46-94 m (41-246 m2 in area), and catchment areas up stream of the sites ranged from 0.44 to 2.01 km2. A total of 487 fish were caught. The species were longfinned and shortfinned eels, banded kokopu, Cran's and redfinned bullies, and common smelt. Eels were the most abundant fish in all three land-use types, and shortfinned eels were more abundant at pastoral sites (mean density 1.11 fish m-2) than longfinned eels (mean density 0.129 fish m-2). Banded kokopu were present only at forested sites. Mean fish densities were greater at pastoral sites (1.55 fish m-2) than under either native forest (0.130 fish m-2) or exotic forest (0.229 fish m-2). Mean fish biomass was also greater at pastoral sites (89.7 g m-2) than under native forest (12.8 g m-2) or exotic forest (19.3 g m-2). Longfinned eels made a greater contribution to the fish biomass at all sites than did shortfinned eels. Densities of crayfish were high (0.46-5.40 crayfish m-2), but were not significantly different between land-use types. Crayfish biomass ranged from 1.79 to 11.2 g m-2. Total eel production was greater at pastoral sites (mean 17.9 g m-2 year-1) than at forest sites (mean 2.39 g m-2 year-1)

Calibration of the Ames Anechoic Facility. Phase 1: Short range plan

A calibration was made of the acoustic and aerodynamic characteristics of a small, open-jet wind tunnel in an anechoic room. The jet nozzle was 102 mm diameter and was operated subsonically. The anechoic-room dimensions were 7.6 m by 5.5 m by 3.4 m high (wedge tip to wedge tip). Noise contours in the chamber were determined by various jet speeds and exhaust collector positions. The optimum nozzle/collector separation from an acoustic standpoint was 2.1 m. Jet velocity profiles and turbulence levels were measured using pressure probes and hot wires. The jet was found to be symmetric, with no unusual characteristics. The turbulence measurements were hampered by oil mist contamination of the airflow

The Star Formation Rate in the Reionization Era as Indicated by Gamma-ray Bursts

High-redshift gamma-ray bursts (GRBs) offer an extraordinary opportunity to study aspects of the early Universe, including the cosmic star formation rate (SFR). Motivated by the two recent highest-z GRBs, GRB 080913 at z = 6.7 and GRB 090423 at z = 8.1, and more than four years of Swift observations, we first confirm that the GRB rate does not trace the SFR in an unbiased way. Correcting for this, we find that the implied SFR to beyond z = 8 is consistent with LBG-based measurements after accounting for unseen galaxies at the faint end of the UV luminosity function. We show that this provides support for the integrated star formation in the range 6 < z < 8 to have been alone sufficient to reionize the Universe.Comment: 4 pages, 4 figures; modified to match version accepted for publication in ApJ Letter

A fault-tolerant multiprocessor architecture for aircraft, volume 1

A fault-tolerant multiprocessor architecture is reported. This architecture, together with a comprehensive information system architecture, has important potential for future aircraft applications. A preliminary definition and assessment of a suitable multiprocessor architecture for such applications is developed

System data communication structures for active-control transport aircraft, volume 2

The application of communication structures to advanced transport aircraft are addressed. First, a set of avionic functional requirements is established, and a baseline set of avionics equipment is defined that will meet the requirements. Three alternative configurations for this equipment are then identified that represent the evolution toward more dispersed systems. Candidate communication structures are proposed for each system configuration, and these are compared using trade off analyses; these analyses emphasize reliability but also address complexity. Multiplex buses are recognized as the likely near term choice with mesh networks being desirable for advanced, highly dispersed systems

Microjansky radio sources in DC0107-46 (Abell 2877)

The cluster DC0107-46 (Abell 2877) lies within the Phoenix Deep Survey, made at 1.4 GHz with the Australia Telescope Compact Array. Of 89 known optical cluster members, 70 lie within the radio survey area. Of these 70 galaxies, 15 (21%) are detected, with luminosities as faint as 10^20 W/Hz. Spectroscopic observations are available for 14/15 of the radio-detected cluster galaxies. Six galaxies show only absorption features and are typical low-luminosity AGN radio sources. One galaxy hosts a Seyfert 2 nucleus, two are star-forming galaxies, and the remaining five may be star-forming galaxies, AGNs, or both.Comment: 14 pages, 3 figures, Accepted by ApJS (v128n2p JUN 2000 issue