Systems, apparatus and techniques for non-invasive optical probing of various substances, and systems, apparatus and techniques for detecting, diagnosing and treating a disease in lungs and other organs using the non-invasive optical probing, including mapping physiological functions of tissues in lungs and other organs. The housing also has an ear hook for fastening the communication unit to the head of a user. Then, whether the tilting state is changed from a face up state to a face down state is determined. The exhaust ring and sized ventilation plugs facilitate optimum engine exhaust porting through the hub assembly for various applications, such as racing and other high performance operation. The apparatus includes an electric motor having a rated motor voltage, a battery pack having an output voltage exceeding the rated motor voltage, and a motor controller which converts the output voltage to supply electrical power to the electric motor at the rated motor voltage. A subterranean servicing fluid comprising carbon dioxide and a hydrocarbon blend wherein the hydrocarbon blend comprises and at least about 65% hydrocarbons having from six carbons to eleven carbons.