Abstract: Notifications for instructing user behavior can be determined and presented when appropriate. Current fitness data are accessed. This data is used to determine whether a user fitness goal is likely to be achieved. If not, a notification may be determined and presented at a user device.

Abstract: A cold gas thruster having a two-stage solenoid is provided. Pressurized gas from the inlet flows to the back side of the piston to hold the piston closed. The pressure is maintained by a check ball held by the solenoid armature. When the solenoid is energized, the armature allows the check ball to move to bleed off the pressure holding the piston closed. The piston moves away from its seat and allows the pressurized gas to flow to the outlet creating thrust. When the solenoid coil is de-energized, the check ball is forced against its seat, which blocks the escape of pressure on the back side of the piston, so that it can re-pressurize back up to the inlet pressure. This creates a force imbalance and moves the piston to close the valve and stop the thrust. Different nozzles can be used for different thrust profiles without changing the solenoid.

Abstract: A practice putting green has an upper surface of material which simulates the green of a golf course and a support which raises the material of the upper surface upon which the practice putting green is positioned. The practice putting green has a generally rectangular shape with long and short sides, and to simulate the slope of a putting green, a support under one of the long sides of the upper surfaces raises that long side of the upper surface to a higher elevation above the underlying surface than the opposing long side. One or more wedges are also provided which may be positioned below the support to create a more uneven playing surface.