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DOI: 10.2514/1.32750 Since October 2005, the T-wing tail-sitter unmanned air vehicle has undergone an extensive program of flight tests, resulting in a total of more than 50 flights, many under autonomous control from takeoff to landing. Starting in August 2006, free flights with conversion between vertical and horizontal flight modes have also been undertaken. Although the latter flights have required some guidance-level ground-pilot input, significant portions of them were performed in autonomous mode, including the transitions between horizontal and vertical flight. This paper considers the overall control architecture of the vehicle, including the different control modes that the vehicle was flown under during the recent series of tests. Although the individual controllers for each flight mode are unremarkable in themselves, it is notable that the aggregate system allows the vehicle to fly throughout its entire flight envelope, which is considerably broader than that of conventional fixed- or rotary-wing vehicles. The performance of the controllers for the different flight modes will also be considered, with a particular focus on hover dispersion results, in differing wind conditions. The majority of these flights were performed on a tether test rig during autonomous control development, to ensure vehicle safety with minimal impact on vehicle dynamics. The demonstration of autonomous flight under the constraints imposed by the tether system in winds up to 18 kt is a significant achievement. Results from the more recent horizontal flight tests with conversions between vertical and horizontal flight are also presented. Most important, these results confirm the basic feasibility of tail-sitter vehicles that use control surfaces submerged in propeller wash for vertical flight control.

Zeuxine gracilis, Zeuxine strateumatica, and Eulophia sinensis are wild orchids with different breeding systems and colonizing abilities. Zeuxine gracilis is an outcrosser with restricted distribution, whereas S. strateumatica is an apomictic colonizer found only in newly available open habitats. Eulophia sinensis is an outcrossing colonizer. This study investigates the levels of genetic variation and patterns of population structure in these wild orchids to provide genetic information for the development of suitable conservation strategies. Lack of allozyme variation was characteristic of all three species, especially in populations of the two colonizing orchids, Z. strateumatica and E. sinensis. More variable markers, randomly amplified polymorphic DNAs (RAPDs), were further employed to characterize population structure of these species. Substantial genetic variation was found at the RAPD loci within populations of Z. gracilis (p = 21.65 [+ or -] 15.88%, A = 1.217 [+ or -] 0.159, and H = 0.076 [+ or -] 0.054) and E. sinensis (p = 17.82 [+ or -] 20.97%, A = 1.179 [+ or -] 0.209, and H = 0.070 [+ or -] 0.084), but little variation existed within populations of Z. strateumatica (p = 2.84 [+ or -] 2.58%, A = 1.029 [+ or -] 0.026, and H = 0.011 [+ or -] 0.011). Regardless of the breeding system, the total gene diversity at the species level was partitioned primarily between populations, as shown by high [G.sub.ST] values, in all three species. An extremely high level of population differentiation ([G.sub.ST] = 0.924) was found in the apomictic colonizer Z. strateumatica. The patterns of genetic variation in these wild orchids are apparently related to their differences in breeding system and colonizing ability. Different conservation strategies are needed for the long-term survival of these species. Key words: allozymes; colonization; Eulophia sinensis; genetic structure; Orchidaceae; RAPD; Zeuxine gracilis; Zeuxine strateumatica.

Goodyera procera is an endangered terrestrial orchid in Hong Kong. Information on its reproductive biology and pattern of genetic variation is needed to develop efficient conservation strategies. Pollination experiments showed that the species is self-compatible, but dependent on pollinators for fruit set. Bagged plants produced no fruits. Artificial pollinations resulted in 92% fruit set through selfing, 94% with geitonogamous pollination, and 95% following xenogamous pollination. Fruit set in the open-pollinated control was 75% at the same sites. Allozyme electrophoresis and random amplified polymorphic DNA (RAPD) were used to evaluate genetic variation and structure of 15 populations of Goodyera procera. Despite its outbreeding system, allozyme data revealed low variation both at the population (P = 21.78%, A = 1.22, and H = 0.073) and species (P = 33%, A = 1.33, and H = 0.15) levels, in comparison with other animal-pollinated outbreeding plant species. However, RAPD variation was relatively high (P = 55. 13% and H = 0.18 at the population level, and P = 97.03% and H = 0.29 at the species level). G(sub ST) estimates indicated high levels of genetic differentiation among populations (G(sub ST) = 0.52 and I = 0.909 +/- 0.049 based on allozyme data, and G(sub ST) = 0.39 and I = 0.859 +/- 0.038 based on RAPD data), much above the average for outcrossing species, suggesting that gene flow was limited in this species. Based on these data, suitable strategies were developed for the genetic conservation and management of the species. Key words: allozymes; conservation genetics; Goodyera procera; Orchidaceae; orchids; pollination biology; RAPD.

The pollination biology, mating system, and population genetic structure of Kandelia candel were investigated. Field observations on its pollination and reproductive biology suggested that this species is pollinator dependent for fruit set, and bee activities can lead to substantial geitonogamous selfing. Quantitative analysis of the mating system parameters was performed using progeny arrays assayed for allozyme markers. Multilocus outcrossing rates ([t.sub.m]) were estimated to be 0.697 [+ or -] 0.091 and 0.797 [+ or -] 0.062 in two populations. In comparison to other plant species with mixed-mating system, the level of allozyme variation was very low in the 13 populations sampled along the coastlines of Hong Kong. At the species level, the proportion of polymorphic loci was 20%, number of alleles per locus was 1.2, and heterozygosity was 0.0362. The total gene diversity was primarily distributed within populations ([H.sub.s] = 0.0339), and the coefficient of genetic differentiation among populations was low ([G.sub.ST] = 0.064). This pattern of population genetic structure suggests that gene flow, primarily in the form of water-dispersed seedlings in viviparous mangrove species, is not as limited as previously thought. However, microgeographic pattern in allele frequency at the marker loci could still be detected between the western and eastern coastal populations. Key words: Kandelia; mangrove; outcrossing rate; pollination biology; population genetic structure; Rhizophoraceae.

A study was conducted on molecular beam epitaxy-grown InAs-on-AlSb interface structures using atomic force microscopy. Results show that the AlAs-like and InSb-like interface bond configurations have different effects on the subsequent InAs layer's morphology. Results also suggest that a rough InAs layer accounts for the effects of the interface configuration on morphology and transport.

The estimates of fat-free mass from X-ray absorptiometry and whole body counting of total body potassium are useful indices of total body protein status in patients with continuous ambulatory peritoneal dialysis. However, similar estimate from creatinine kinetics fails to provide an accurate index for total body protein level. The estimates from X-ray absorptiometry and whole body counting show the total body protein status even at significantly reduced levels.