277 research outputs found
Long-term development of experimental mixtures of Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Roth.) in northern Britain
The Caledonian pinewoods of northern Scotland are a priority conservation habitat in Europe which are dominated by Scots pine (Pinus sylvestris), but varying proportions of a number of broadleaved species such as silver birch (Betula pendula) can occur in these forests. Better understanding of the dynamics of mixed Scots pine-birch stands would be helpful in informing current initiatives to restore and increase the area of the pinewood ecosystem. Some evidence is provided by two experiments established in the 1960s which compared plots of pure Scots pine and pure birch with two treatments where the two species were mixed in 3:1 and 1:1 ratios. Some fifty years later, Scots pine was the more vigorous of the two species in these experiments, being both taller and significantly larger in diameter. The highest basal area was generally found in the pure Scots pine plots and the values in the mixed plots tended to be intermediate between those of the two component species. Examination of the growth in the mixed plots showed a slight, but non-significant, tendency towards overyielding. This appeared to be due to Scots pine growth being better than predicted, while that of birch was slightly less than predicted. These results suggest that in these mixtures, which are composed of two light demanding species, the main mechanism driving long-term performance is competition for light and there is little evidence of any complementary effect. These results suggest that any strategy seeking to increase the long-term representation of broadleaves such as birch in the Caledonian pinewoods will need to create discrete blocks that are large enough to withstand the competitive pressures exerted by the pine
Developing a GamePlan: Libraries and Campus Athletic Departments
At a number of academic libraries, librarians have begun partnering with Athletic Departments to deliver information literacy to freshman athletes. This breakout session will present three different endeavors designed to meet the needs of the incoming student athlete.
UCLA’s College Library has recently expanded collaboration with their athletic department from an annual one-shot for incoming football players to an ongoing partnership integrating library instruction and awareness into the freshman football and basketball teams’ total academic experience.
Arizona State University faced two challenges: help student-athletes learn to use the Library\u27s resources, and train their tutors and mentors. Every ASU freshman athlete takes a one-credit Life Skills course, and working in collaboration with the Office of Student Athlete Development, the Instruction team had the unprecedented opportunity to help design the curriculum for a library-focused unit that would not only teach the athletes and their academic coaches about the available resources, but also require the students to write a reflective essay on the experience of searching for relevant information in a library resource.
At Willamette University, the librarians have worked with the Athletic Department to create a program called “GamePlan”. The program, which now includes football, crew, basketball, soccer and volleyball teams, is in its third year. Each Fall semester is treated as an “information challenge”, broken up into seven different 20-minute sessions. The sessions, held in the evenings, are focused on individual topics with explicit objectives
Predators Show Seasonal Predilections for Model Clay Spiders in an Urban Environment
Predator-prey interactions may be altered under human-induced rapid environmental change, such as urbanisation. Extensive clearing in urban areas may leave short-range endemic species, such as mygalomorph spiders, more vulnerable to local extinction through predation in remaining remnants. Predation rates on Australian mygalomorph spiders were assessed using clay models of two size classes (5 cm, 3 cm), during two time periods in 2016 (January–February, July–August). Size and phenology of models resembled the mygalomorph genera Aname and Teyl occurring in these local urban remnants. Local predator guilds were significantly influenced by leaf-litter cover (%) and proportion of surrounding parkland. Preference for spider vs. control models was consistent across all predator types (bird, rodent, lizard and wasp), but specialist spider wasps (Pompilidae) only attacked spider models. Generalist predators (birds, lizards and rodents) were more opportunistic. Lizards and rodents exhibit similar predation behaviour, indicating there may be some inter-specific competition. Invasive generalists (e. g. rodents) or urban adapters (e. g. corvids) are more likely to represent an increased threat to spiders than are co-evolved specialists (e.g. spider wasps)
Black Bear Sideliner, vol. 2, no. 1
Black Bear Sideliner biannual newsletter produced by UMaine Athletics
Paper Session II-C - Command and Control Through Space-Based Systems
A new space-based command and control concept is presented that combines a ground station in conjunction with satellites utilizing modern RF communications technology. By using current satellites such as TDRSS, GPS or the proposed LEO/MEO commercial constellations, the command system of the future will provide a reliable and highly redundant replacement for the current command system that requires as many as seven UHF transmitter sites along the various launch vehiclesÕ flight paths. This space-based command system requires a look at new technologies to provide innovative ways to transmit secure and jam resistant messages from the launch operations center. These messages would then be relayed through a satellite to the launch vehicle and back to the operations center for confirmation. This new command system must conform to Range Safety guidelines in terms of minimal propagation time, communication security, maximum reliability and design efficiency to ensure that no single point of failure will deny the capability to terminate or result in the inadvertent termination of a launch vehicle or payload
The Next Generation of High-Speed Dynamic Stability Wind Tunnel Testing (Invited)
Throughout industry, accurate measurement and modeling of dynamic derivative data at high-speed conditions has been an ongoing challenge. The expansion of flight envelopes and non-conventional vehicle design has greatly increased the demand for accurate prediction and modeling of vehicle dynamic behavior. With these issues in mind, NASA Langley Research Center (LaRC) embarked on the development and shakedown of a high-speed dynamic stability test technique that addresses the longstanding problem of accurately measuring dynamic derivatives outside the low-speed regime. The new test technique was built upon legacy technology, replacing an antiquated forced oscillation system, and greatly expanding the capabilities beyond classic forced oscillation testing at both low and high speeds. The modern system is capable of providing a snapshot of dynamic behavior over a periodic cycle for varying frequencies, not just a damping derivative term at a single frequency
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