Pentatomidae of Arkansas

A total of 30 genera and 53 species and subspecies of Pentatomidae are reported as occurring or possibly occurring in Arkansas. Fifty species and subspecies contained in 29 genera were collected or recorded from previously collected material. Based on distributional records in the literature, three additional species and one genus are listed as probably occurring in Arkansas. County and seasonal records are reported for each taxon

Soil Traversing Arthropod Populations as Sampled by Pitfall Traps in Sunflower and Three Adjacent Habitats in Northeast Arkansas

Soil traversing arthropod populations were sampled by pitfall traps in sunflower (Helianthus spp.) and three adjacent habitats during the months of July, August and September of 1980 and May, June, July and August of 1981. In1980, four varieties of sunflower (Ellar, Hybrid 670, 891 and S-345) were planted. A single variety of sunflower (Ellar) was planted in1981. The three adjacent habitats in both 1980 and 1981 were a pine stand, grass border and fence row. Of 1,748 specimens collected in 1980, 17 orders and 48 families were represented. Four orders comprised 78% of the total catch: Hymenoptera (45%), Acari (17%), Collembola(11%) and Coleoptera (5%). In 1981, 20 orders and 64 families were represented in a total of 26,693 trapped specimens. Four orders composed 88% of the total catch: Collembola (57%), Acari (14%), Hymenoptera (11%) and Homoptera (6%). Family composition and seasonal occurrence are discussed and compared for habitats sampled. Weather data are presented and discussed in relation to arthropod activit

Application of adaptive antenna techniques to future commercial satellite communication

The purpose of this contract was to identify the application of adaptive antenna technique in future operational commercial satellite communication systems and to quantify potential benefits. The contract consisted of two major subtasks. Task 1, Assessment of Future Commercial Satellite System Requirements, was generally referred to as the Adaptive section. Task 2 dealt with Pointing Error Compensation Study for a Multiple Scanning/Fixed Spot Beam Reflector Antenna System and was referred to as the reconfigurable system. Each of these tasks was further sub-divided into smaller subtasks. It should also be noted that the reconfigurable system is usually defined as an open-loop system while the adaptive system is a closed-loop system. The differences between the open- and closed-loop systems were defined. Both the adaptive and reconfigurable systems were explained and the potential applications of such systems were presented in the context of commercial communication satellite systems

Application of adaptive antenna techniques to future commercial satellite communications. Executive summary

The purpose of this contract was to identify the application of adaptive antenna technique in future operational commercial satellite communication systems and to quantify potential benefits. The contract consisted of two major subtasks. Task 1, Assessment of Future Commercial Satellite System Requirements, was generally referred to as the Adaptive section. Task 2 dealt with Pointing Error Compensation Study for a Multiple Scanning/Fixed Spot Beam Reflector Antenna System and was referred to as the reconfigurable system. Each of these tasks was further subdivided into smaller subtasks. It should also be noted that the reconfigurable system is usually defined as an open-loop system while the adaptive system is a closed-loop system. The differences between the open- and closed-loop systems were defined. Both the adaptive and reconfigurable systems were explained and the potential applications of such systems were presented in the context of commercial communication satellite systems

Polarization Structures in the Thomson-Scattered Emission Lines in Active Galactic Nuclei

A line photon incident in an electron-scattering medium is transferred in a diffusive way both in real space and in frequency space, and the mean number of scatterings changes as the wavelength shifts from the line center. This leads to the profile broadening and polarization dependence on the wavelength shift as a function of the Thomson optical depth $\tau_T$. We find that the polarization of the Thomson-scattered emission lines has a dip around the line center when $\tau_T$ does not exceed a few. Various structures such as the polarization flip are also seen. An application to an ionized halo component surrounding the broad emission line region in active galactic nuclei is considered and it is found that the polarization structures may still persist. Brief discussions on observational implications are given.Comment: 14 pages, 3 figures, accepted for publication in ApJ Letter

The Formation of High-Mass Black Holes in Low Mass X-ray Binaries

In this note we suggest that high-mass black holes; i.e., black holes of several solar masses, can be formed in binaries with low-mass main-sequence companions, provided that the hydrogen envelope of the massive star is removed in common envelope evolution which begins only after the massive star has finished He core burning. That is, the massive star is in the supergiant stage, which lasts only $\sim 10^4$ years, so effects of mass loss by He winds are small. Since the removal of the hydrogen envelope of the massive star occurs so late, it evolves essentially as a single star, rather than one in a binary. Thus, we can use evolutionary calculations of Woosley & Weaver (1995) of single stars. We find that the black holes in transient sources can be formed from stars with ZAMS masses in the interval 20-35\msun. The black hole mass is only slightly smaller than the He core mass, typically \sim 7\msun.Comment: 19 pages, substantial changes, accepted in New Astronom