RESUMEN
Apteryx is a genus of flightless birds endemic to New Zealand known to lay very large eggs in proportion to body weight. The eggshell of Apteryx is unusually thin and less porous than allometrically expected possibly as a compensation for a very long incubation period. Past studies have been carried out on Apteryx australis, a species which once comprised all kiwi with brown plumage, now separated into three distinct species. These species use different habitats and live at different latitudes and altitudes, therefore generating a need to revise our knowledge of the attributes of their eggshells. In this study, we measured the physical characteristics and water conductance on eggshell fragments of these three species and Great-spotted Kiwi and relate them to the environmental conditions of their respective environments; we also measured the water vapor conductance of Brown Kiwi eggs of late stages of incubation. We found that several trade-offs exist between incubation behavior, environmental conditions, and eggshell structure. We found differences between species in eggshell water vapor conductance seemingly related to altitude; Brown Kiwi and Rowi generally inhabiting lower altitudes had the highest conductance and Tokoeka, generally living in montane environments, the lowest. This is achieved by an increased eggshell thickness rather than a pore area reduction. Finally, the water vapor conductance late in incubation was 58% higher than infertile unincubated eggs, suggesting a drastic increase in conductance throughout the long incubation period. Using the values previously reported, we calculated the embryonic eggshell thinning to be 32.5% at the equatorial region of the eggshell. We describe several new features, such as triangular mineral particles in the cuticle, reported for the extinct Trigonoolithus amoei, and confirmed the existence of plugged pores. We suggest that these structures provide microbial protection needed by a burrow nesting species with a long incubation period.
RESUMEN
We describe the design and implementation of a controller-area-network bus (CANbus) monitor and control system for a millimeter wave interferometer. The Combined Array for Research in Millimeter-wave Astronomy (CARMA) is a 15-antenna connected-element interferometer for astronomical imaging, created by the merger of two university observatories. Its new control system relies on a central computer supervising a variety of subsystem computers, many of which control distributed intelligent nodes over CANbus. Subsystems are located in the control building and in individual antennas and communicate with the central computer via Ethernet. Each of the CAN modules has a very specific function, such as reading an antenna encoder or tuning an oscillator. Hardware for the modules was based on a core design including a commercial CANbus-enabled single-board computer and some standard circuitry for interfacing to peripherals. Hardware elements were added or changed as necessary for the specific module types. Similarly, a base set of embedded code was implemented for essential common functions such as CAN message handling and time keeping and extended to implement the required functionality for the different hardware. Using a standard CAN messaging protocol designed to fit the requirements of CARMA and a well-defined interface to the high-level software allowed separate development of high-level code and embedded code with minimal integration problems. Over 30 module types have been implemented and successfully deployed in CARMA, which is now delivering excellent new science data.