Spacecraft component heater control system

A heater control circuit is disclosed as being constructed in a single integrated circuit, with the integrated circuit conveniently mounted proximate to a spacecraft component requiring temperature control. Redundant heater controllers control power applied to strip heaters disposed to provide heat to a component responsive to sensed temperature from temperature sensors. Signals from these sensors are digitized and compared with a dead band temperature and set point temperature stored in memory to generate an error signal if the sensed temperature is outside the parameter stored in the memory. This error signal is utilized by a microprocessor to selectively instruct the heater controllers to apply power to the strip heaters. If necessary, the spacecraft central processor may access or interrogate the microprocessor in order to alter the set point temperature and dead band temperature range to obtain operational data relating to the operation of an integrated circuit for relaying to the ground control, or to switch off faulty components

Comparing resolved-sideband cooling and measurement-based feedback cooling on an equal footing: analytical results in the regime of ground-state cooling

We show that in the regime of ground-state cooling, simple expressions can be derived for the performance of resolved-sideband cooling --- an example of coherent feedback control --- and optimal linear measurement-based feedback cooling for a harmonic oscillator. These results are valid to leading order in the small parameters that define this regime. They provide insight into the origins of the limitations of coherent and measurement-based feedback for linear systems, and the relationship between them. These limitations are not fundamental bounds imposed by quantum mechanics, but are due to the fact that both cooling methods are restricted to use only a linear interaction with the resonator. We compare the performance of the two methods on an equal footing --- that is, for the same interaction strength --- and confirm that coherent feedback is able to make much better use of the linear interaction than measurement-based feedback. We find that this performance gap is caused not by the back-action noise of the measurement but by the projection noise. We also obtain simple expressions for the maximal cooling that can be obtained by both methods in this regime, optimized over the interaction strength.Comment: 14 pages, 2 png figures; v2: revised for publicatio

Hyperthyroid state

This issue of eMedRef provides information to clinicians on the pathophysiology, diagnosis, and therapeutics of a hyperthyroid state

A Management Model for Specification of Groundwater Withdrawal Permits

The Massachusetts Water Management Act was enacted in 1986 to preserve the State\u27s water resources. The intent of the Act was to allow for sustained economic growth while protecting the natural environment by minimizing the occurrence of low stream flows. As a result of the act, a permit must be obtained for new water withdrawals (including increases on existing withdrawals) of more than 0.1 million gallons per day (0.00438 m3/s). The permits specify the degree to which applicants may withdraw water, and reserve the right to curtail use during low flow seasons. A linear programming model is presented that is capable of assisting regulatory agencies in specifying details of permits for groundwater use. The model links ground water withdrawals with surface streamflow, considering consumptive use and interbasin transfers. The optimization minimizes the depletion of streamflow below a standard while honoring the statistical distribution of allowed withdrawals permitted each applicant. The results specify the amount and timing of allowed withdrawals throughout the year

Scanning Electron Microscopy of Early Dinosaur Egg Shell Structure: A Comparison with Other Rigid Sauropsid Eggs

Fossil eggs attributable to dinosaur (probably prosauropod) parentage that have been recovered from the early Jurassic Elliot Formation sediments at the Rooidraai locality possess shells that are similar to those of birds and crocodilians, and distinctly unlike those of chelonians and gekkonids. The preserved shell is very thin, and distinct mammillary processes are lacking, although the inner surface displays an undulating contour. The absence of these processes may be attributable to the inner portion of the shell having been at least partially decalcified during incubation and not preserved in the fossil state. The shells appear to be composed of broadly wedge-shaped, albeit ill-defined calcareous units, and they are similar to those of birds and other dinosaurs in the pattern of cleavage shown by the tabular calcite crystals of the palisade layer, and in the absence of the dominant horizontal lamellae that characterize crocodilian shells. The differential resemblance of these early Jurassic shells to the eggs of other closely related sauropsid taxa may be pertinent to questions concerning the evolution of egg shell structure within this clade