Selected tether applications in space: Phase 2

System characteristics and design requirements are assessed for tether deployment. Criteria are established for comparing alternate concepts for: (1) deployment of 220 klb space shuttle from the space station; (2) tether assisted launch of a 20,000 lb payload to geosynchronous orbit; (3) placement of the 20,000 lb AXAF into 320 nmi orbit via orbiter; (4) retrieval of 20,000 lb AXAF from 205 nmi circular orbit for maintenance and reboost to 320 nmi; and (5) tethered OMV rendezvous and retrieval of OTV returning from a geosynchronous mission. Tether deployment systems and technical issues are discussed

Heteroepitaxy of 3-5 compound semiconductors on insulating substrates Interim report

Heteroepitaxial growth of GaAs films on aluminum oxide substrates by trimethylgallium-arsine proces

Dynamic Pattern Formation in a Vesicle-Generating Microfluidic Device

Spatiotemporal pattern formation occurs in a variety of nonequilibrium physical and chemical systems. Here we show that a microfluidic device designed to produce reverse micelles can generate complex, ordered patterns as it is continuously operated far from thermodynamic equilibrium. Flow in a microfluidic system is usually simple—viscous effects dominate and the low Reynolds number leads to laminar flow. Self-assembly of the vesicles into patterns depends on channel geometry and relative fluid pressures, enabling the production of motifs ranging from monodisperse droplets to helices and ribbons

Smartphone app reveals that lynx avoid human recreationists on local scale, but not home range scale

Outdoor recreation is increasing and affects habitat use and selection by wildlife. These effects are challenging to study, especially for elusive species with large spatial requirements, as it is hard to obtain reliable proxies of recreational intensity over extensive areas. Commonly used proxies, such as the density of, or distance to, hiking paths, ignore outdoor recreation occurring on other linear feature types. Here we utilized crowdsourced data from the Strava training app to obtain a large-scale proxy for pedestrian outdoor recreation intensity in southeast Norway. We used the proxy and GPS-tracking data from collared Eurasian lynx (Lynx lynx) to investigate how recreation affects habitat selection at the home range scale and local scale by lynx during summer. We fitted resource selection functions at the two scales using conditional logistic regression. Our analysis revealed that lynx avoided areas of recreational activity at the local scale, but not at home range scale. Nonetheless, lynx frequently used areas associated with recreation, and to a greater degree at night than during the day. Our results suggest that local-scale avoidance of recreation and temporal adjustments of habitat use by lynx mitigate the need for a home range-scale response towards recreation. Scale-dependent responses and temporal adjustments in habitat use may facilitate coexistence between humans and large carnivores

Movement and habitat selection of a large carnivore in response to human infrastructure differs by life stage

BackgroundThe movement extent of mammals is influenced by human-modified areas, which can affect population demographics. Understanding how human infrastructure influences movement at different life stages is important for wildlife management. This is true especially for large carnivores, due to their substantial space requirements and potential for conflict with humans.MethodsWe investigated human impact on movement and habitat selection by GPS-collared male brown bears (Ursus arctos) in two life stages (residents and dispersers) in central Sweden. We identified dispersers visually based on their GPS locations and used hidden Markov models to delineate dispersal events. We used integrated step selection analysis (iSSA) to infer movement and habitat selection at a local scale (availability defined by hourly relocations), and resource selection functions (RSFs) to infer habitat selection at a landscape scale (availability defined by the study area extent).ResultsMovement of residents on a local scale was facilitated by small forestry roads as they moved faster and selected areas closer to forestry roads, and they avoided areas closer to larger public roads and buildings on both scales. Dispersers were more ambivalent in their response to human infrastructure. Dispersers increased their speed closer to small forestry roads and larger public roads, did not exhibit selection for or against any road class, and avoided areas closer to buildings only at local scale. Dispersers did not select for any features on the landscape, which is likely explained by the novelty of the landscape or their naivety towards it.ConclusionOur results show that movement in male brown bears is life stage-dependent and indicate that connectivity maps derived from movement data of dispersing animals may provide more numerous and more realistic pathways than those derived from resident animal data alone. This suggests that data from dispersing animals provide more realistic models for reconnecting populations and maintaining connectivity than if data were derived from resident animals alone

Altitude, latitude and climate zone as determinants of mountain hare (Lepus timidus) coat colour change

Local adaptation to annually changing environments has evolved in numerous species. Seasonal coat colour change is an adaptation that has evolved in multiple mammal and bird species occupying areas that experience seasonal snow cover. It has a critical impact on fitness as predation risk may increase when an individual is mismatched against its habitat's background colour. In this paper, we investigate the correlation between landscape covariates and moult timing in a native winter-adapted herbivore, the mountain hare (Lepus timidus), throughout Norway. Data was collected between 2011 and 2019 at 678 camera trap locations deployed across an environmental gradient. Based on this data, we created a Bayesian multinomial logistic regression model that quantified the correlations between landscape covariates and coat colour phenology and analysed among season and year moult timing variation. Our results demonstrate that mountain hare moult timing is strongly correlated with altitude and latitude with hares that live at higher latitudes and altitudes keeping their winter white coats for longer than their conspecifics that inhabit lower latitudes and altitudes. Moult timing was also weakly correlated with climate zone with hares that live in coastal climates keeping their winter white coats for longer than hares that live in continental climates. We found evidence of some among year moult timing variation in spring, but not in autumn. We conclude that mountain hare moult timing has adapted to local environmental conditions throughout Norway

Forestry and environmental conditions as determinants of pine marten Martes martes occurrence in Norway

The European pine marten Martes martes is often associated with late seral stage coniferous forest stands. Earlier research has indicated that this species may be negatively influenced by clearcutting practices. However, the effects of current clearcutting methods on pine marten occurrence in conjunction with changing environmental conditions are not well known. In this study, we combined four complete years of nationwide data collected during a long-term camera trap (CT) monitoring program in Norway. We employed a multi-scale occupancy model to investigate the relationship of pine marten occurrence to clearcuts (regenerating stands & LE; 10 years old) and forests & GE; 120 years old. We also examined pine marten detection in relation to habitat features (i.e. dominant microsite characteristics) and to varying snow depths and temperatures. We found no relationship between pine marten occurrence and the proportions of old forest and clearcuts at the landscape scale. At the habitat-patch scale, pine marten occurrence was positively associated with the presence of old forest patches and terrain ruggedness, but not with clearcuts & LE; 100 m from sites. At CT sites near clearcuts, the detection probability was negatively correlated with snow depth. In contrast, pine marten occurrence was positively associated with snow depth at CT sites > 100 m from clearcuts. Furthermore, the detection probability increased with temperature and the presence of boulders at CT sites. Boulders may provide important access points for foraging, and cover for resting and predator avoidance. While previous studies indicate that pine martens prefer older forest and avoid clearcuts, the current level and scale of clearcutting in Norway does not appear to influence its occurrence at the landscape scale