61.   The change in internal energy AU of a system is thus the heat absorbed by the system when the reaction occurs at constant volume.

62.   The enthalpy change, H, of a system is thus the heat absorbed by the system when the reaction occurs at constant pressure.

63.   In other words, when a spontaneous reaction occurs at constant temperature and pressure, the free energy of the system decreases.

64.   This occurs at the melting point.

65.   Suitable scenes of red-faced hilarity would occur back at the office as someone always tipped off the entire staff to be ready at the front door.

66.   We would suggest that an altered metabolism may occur at the large polyp or cancer stage.

67.   Some of these changes seem to occur at an early stage of the neoplastic process.

68.   Syncope is unrelated to plasma concentrations of quinidine or duration of therapy, and torsades de pointes can occur at low plasma concentrations.

69.   Only limited continental subduction appears to have occurred at this stage.

70.   This might be explained by sub-lithospheric thermal anomalies causing uplift without penetrative magmatism developing to a point where volcanic activity occurs at the surface.