The sopite syndrome revisited: drowsiness and mood changes during real or apparent motion

The sopite syndrome is a poorly understood response to motion. Drowsiness and mood changes are the primary characteristics of the syndrome. The sopite syndrome can exist in isolation from more apparent symptoms such as nausea, can last long after nausea has subsided, and can debilitate some individuals. It is most likely a distinct syndrome from "regular" motion sickness or common fatigue, and is of potential concern in a variety of situations. The syndrome may be particularly hazardous in transportation settings where other performance challenges (e.g., sleep deprivation) are already present. It is also a potential concern in cases where illnesses such as sleep disorders or depression may interact with the syndrome and confuse diagnosis.     

Neutral points on the boundary of the closed magnetosphere

Theoretical studies of a field-free plasma incident upon a magnetic dipole lead to a closed magnetosphere with two neutral points in the noon magnetic meridian, at a latitude of ± 70°–75° and a geocentric distance of approximately 10 R_E. The position of the neutral points with respect to the dipole axis is not greatly affected by the angle of incidence of the solar wind. Although the field magnitude near the neutral points is only a fraction of the dipole field, the direction is seen to reverse on opposite sides of the neutral point. Near the boundary the field direction is parallel to the boundary and tends to point towards the neutral point in the Northern hemisphere.     

Linear filtering approaches for phase calibration of airborne arrays

Phase calibration of a large fluctuating millimeter-wave airborne antenna array is considered. The technique exploits properties of the correlation of the measured voltages arising from clutter returns at adjacent or nearby element pairs. The proposed calibration algorithm trades smoothing of the observations to reduce random errors with the ability to track the time-varying calibration phase. Algorithm performance is considered for an arbitrary linear filter, which generalizes previous work on analogous pulse-pair problems, and the results are used to choose optimal filter parameters. Numerical results are provided for a field experiment employing a 32-element Ku-band antenna array