The United States 2002 Unified Command Plan: Antarctica and the areas of responsibility of military commanders

ABSTRACTIn October 2002, following the 11 September 2001 attacks on the United States, the Unified Command Plan (UCP), that sets out the geographical responsibilities of combatant commanders, was revised with regard to their areas of responsibility. Accompanying these changes was a map, which detailed the geographical boundaries of the US Northern, Pacific, Southern, European and Central Commands. The map indicated that two of these Commands, Southern and European Command stretched as far south as the Antarctic coastline while a third (Pacific) not only did that but also included the entire Antarctic continent. In 2007, a new Africa Command comprising the southern part of European Command, was instituted and this, too, stretched to the Antarctic coastline. This note briefly considers some of the implications that might follow from these changes to the UCP and highlights logistical patterns, search and rescue matters and the question of the demilitarisation of Antarctica.

Central and baroreflex control of heart period during the wake-sleep cycle in spontaneously hypertensive rats

We investigated whether the relative contribution of the baroreflex and central commands to the control of heart period differs between spontaneously hypertensive rats (SHR) and Wistar-Kyoto normotensive rats (WKY) during physiological behavior. Rats were instrumented with an arterial catheter and with electrodes for discriminating wakefulness, nonrapid eye movement sleep (NREMS), and rapid eye movement sleep (REMS). The cross-correlation function (CCF) between spontaneous fluctuations of heart period and mean arterial pressure was computed at frequencies <0.2 Hz. The baroreflex determines a positive correlation between heart period and previous pressure values. This pattern was observed in the CCF during quiet wakefulness (QW) and NREMS, and in QW, it was accompanied by a pronounced negative correlation between heart period and subsequent pressure values. The relative baroreflex contribution to the control of heart period, estimated from the positive peak value of the CCF, was lower in SHR than in WKY during QW but not during NREMS. During REMS, the CCF showed a negative correlation between heart period and both previous and subsequent pressure values, reflecting the prevalence of central autonomic commands. The relative contribution of central commands to the control of heart period, estimated from the negative peak value of the CCF, was lower in SHR than in WKY during REMS. These results suggest that during QW and REMS, the control of heart period exerted by the baroreflex and central commands, respectively, is less effective in SHR than in WKY. This difference is not apparent in a behavioral state of autonomic stability such as NREMS.

Evaluation of central commands: Toward a theoretical basis for rehabilitation

The commentary focuses on the need for motor control modeling as a rationale for rehabilitation. We give examples in a bimanual unloading task and examine the potential consequences for recovery in patients with cerebral lesions. Hierarchical models of motor control lead to a distinction between “task optimization” and “motor optimization” and to a qualifier on Latash & Anson's “hands-off” position.

The unobservability of central commands: Why testing hypotheses is so difficult

The experiments Feldman and Levin suggest do not definitively test their proposed solution to the problem of selecting muscle activations. Their test of the movement directions that elicit EMG activity can be interpreted without regard to the form of the central commands, and their fast elbow flexion test is based on a forward computation that obscures the insensitivity of the predicted trajectory to the details of the putative commands.