A planar near-field scanning technique for bistatic radar cross section measurements

A progress report on the development of a bistatic radar cross section (RCS) measurement range is presented. A technique using one parabolic reflector and a planar scanning probe antenna is analyzed. The field pattern in the test zone is computed using a spatial array of signal sources. It achieved an illumination pattern with 1 dB amplitude and 15 degree phase ripple over the target zone. The required scan plane size is found to be proportional to the size of the desired test target. Scan plane probe sample spacing can be increased beyond the Nyquist lambda/2 limit permitting constant probe sample spacing over a range of frequencies

Planar near-field scanning for compact range bistatic radar cross-section measurement

The design, construction, and testing of a low cost, planar scanning system to be used in a compact range environment for bistatic radar cross-section (bistatic RCS) measurement data are discussed. This scanning system is similar to structures used for measuring near-field antenna patterns. A synthetic aperture technique is used for plane wave reception. System testing entailed comparison of measured and theoretical bistatic RCS of a sphere and a right circular cylinder. Bistatic scattering analysis of the ogival target support, target and pedestal interactions, and compact range room was necessary to determine measurement validity

Thelastomatid Nematodes (Oxyurida: Thelastomatoidea) from the Peppered Cockroach, Archimandrita tesselata (Insecta: Blattaria) in Costa Rica

Six species of thelastomatid nematodes belonging to 6 different genera were collected from the peppered cockroach Archimandrita tesselata Rehn, 1903, at the Area de Conservación Guanacaste, Costa Rica, from 2003 to 2006. We describe Aoruroides costaricensis n. sp. This species differs from the other described members of the genus in female cephalic morphology and male papillae arrangement as well as having different morphological dimensions including a shorter female esophagus than that of Aoruroides philippinensis (Chitwood and Chitwood, 1933) and Aoruroides queenslandensis Jex, Cribb, and Schneider, 2004, longer esophageal corpus and isthmus than in Aoruroides legionarius Kloss, 1966, and a much shorter male tail than that of A. legionarius Kloss, 1966. The 5 additional species recovered included Buzionema validum, Protrelleta floridana, Cranifera cranifera, Hammerschmidtiella diesingi, and an unidentified species from the family Thelastomatidae. These species are redescribed using light and scanning electron microscopy and constitute new host and geographical records

First Record of \u3ci\u3eCephalobellus brevicaudatus\u3c/i\u3e (Leidy, 1851) Christie, 1933 (Nematoda: Oxyurida: Thelastomatoidea), from Cranefly Larvae (Diptera: Tipulidae) in Ohio, U.S.A.

Specimens of the tipulid (cranefly) larvae Tipula (Pterelachisas) sp. Rondani (n = 118) were recovered from rotting logs in 2 forests of central Ohio from 2011 to 2016. Examination of the posterior intestine revealed the presence of the thelastomatid nematode Cephalobellus brevicaudatus (Leidy, 1851) Christie, 1933. This finding constitutes the first North American record for the parasite in a dipteran larva and the first Nearctic report of this species since 1851. First morphological data for the males from North America are provided, and voucher ribosomal DNA sequences for C. brevicaudatus and for the hosts were compiled

Prevalence of feather-degrading Bacillus spp. on the plumage of birds in Australia

Bird plumage hosts a diverse microbial community, including microbes capable of degrading the β-keratin in feathers (i.e. feather-degrading bacteria). The prevalence and effects of feather-degrading bacteria have primarily been studied in the Northern Hemisphere, and knowledge of the occurrence of these bacteria on Southern Hemisphere bird species is lacking. We explored the prevalence of feather-degrading bacteria on wild birds in Australia by sampling feathers from 254 individuals representing 25 species. First, to determine the total plumage bacterial load, we sampled bacteria from three body regions and identified and enumerated three presumed feather-degrading Bacillus spp. (B. licheniformis, B. cereus, and B. subtilis) based on morphology. Second, we collected a feather from each bird and in laboratory tests confirmed the presence of feather-degrading bacteria. Third, we tested for a relationship between the number of presumed feather-degrading Bacillus spp. counted and the presence of feather-degrading bacteria on the following variables: habitat type, foraging behaviour, flocking status, and feather wear. We found 85% of birds sampled harboured presumed Bacillus spp. Of the feather samples that tested positive for Bacillus in lab experiments, 62% were confirmed as feather-degrading Bacillus spp. The total plumage bacterial load varied with habitat type, with birds in heath habitats harbouring fewer bacteria. This study is the first report of feather-degrading bacteria on the plumage of wild Australian birds in vivo