Abstract: A cryoablation system including a cannula having a proximal end, a distal end, and a longitudinal axis, an expandable balloon extending from the distal end of the cannula and fluidly connected to a source of heat transfer fluid by at least one fluid path, a pump for circulating the heat transfer fluid into and out of the balloon, a probe handle coupled to the proximal end of the cannula and in fluidic communication with the balloon through the cannula, and a heat exchanger for varying the temperature of the heat transfer fluid, wherein the heat exchanger is fluidly connected to a secondary refrigerant source. The heat exchanger may be positioned within the probe handle, within the cannula, or at least partially within the balloon. The heat transfer fluid of this cryoablation system preferably has a freezing point lower than about ?110° C. and a boiling point greater than about 50° C.

Abstract: A cryoablation system including a cannula having a proximal end, a distal end, and a longitudinal axis, an expandable balloon extending from the distal end of the cannula and fluidly connected to a source of heat transfer fluid by at least one fluid path, a pump for circulating the heat transfer fluid into and out of the balloon, a probe handle coupled to the proximal end of the cannula and in fluidic communication with the balloon through the cannula, and a heat exchanger for varying the temperature of the heat transfer fluid, wherein the heat exchanger is fluidly connected to a secondary refrigerant source. The heat exchanger may be positioned within the probe handle, within the cannula, or at least partially within the balloon. The heat transfer fluid of this cryoablation system preferably has a freezing point lower than about ?110° C. and a boiling point greater than about 50° C.

Abstract: A cryoablation system for performing endometrial ablation comprising an elongated tubular cannula having a proximal end, a distal end, and a longitudinal axis, an expandable balloon extending from the distal end of the cannula and fluidly connected to a source of heat transfer fluid by at least one fluid path, a pump for circulating the heat transfer fluid into and out of the balloon, a probe handle coupled to the proximal end of the cannula and in fluidic communication with the balloon through the cannula, and a heat exchanger for varying the temperature of the heat transfer fluid, wherein the heat exchanger is fluidly connected to a secondary refrigerant source, and wherein the heat exchanger comprises an outer tubular wall and a plurality of fins extending from the tubular wall toward the interior portion of the heat exchanger.

Abstract: A system including (i) a primary loop including a first oil compressor configured to raise the pressure of a refrigerant flowing through the primary loop, an oil separator configured to separate oil contaminant from the refrigerant, a valve configured to return the separated oil back to the first oil compressor, at least one heat exchanger, and a first expansion element; and (ii) a secondary loop including a primary/secondary heat exchanger, the primary/secondary heat exchanger also forming a part of the primary loop; wherein the refrigerant includes constituents (a) that function as a solvent of the oil contaminant which fail to be separated from the refrigerant and (b) that at least substantially condense in the primary/secondary heat exchanger.

Abstract: In a free piston machine, initial collisions of the piston with structures at the end of the cylinder are detected and generate a change in the magnitude of a perturbation signal, which is applied to the summing junction of a closed loop feedback control system controlling a piston force. The change is applied in a direction to reduce piston amplitude. In embodiments in which maximization of piston amplitude is desirable, the magnitude of the perturbation signal is also varied in the opposite direction in the absence of collisions to increase piston amplitude of oscillation so that operation then hunts between initial nondestructive collisions and a non-colliding maximum amplitude of piston oscillation.

Abstract: In a free piston machine, initial collisions of the piston with structures at the end of the cylinder are detected and generate a change in the magnitude of a perturbation signal, which is applied to the summing junction of a closed loop feedback control system controlling a piston force. The change is applied in a direction to reduce piston amplitude. In embodiments in which maximization of piston amplitude is desirable, the magnitude of the perturbation signal is also varied in the opposite direction in the absence of collisions to increase piston amplitude of oscillation so that operation then hunts between initial nondestructive collisions and a non-colliding maximum amplitude of piston oscillation.

Abstract: A refrigeration system having a modulatable compressor and a Rankine cycle refrigeration circuit having at least two evaporators. The flow rate of the compressor is modulated in response to the sensed temperature of the masses being cooled, and the control circuit switches valves to control the refrigerant flow path and modulates the flow rate of the compressor to optimize the efficiency of the refrigeration system.

Abstract: A refrigeration system having a modulatable compressor and a Rankine cycle refrigeration circuit having at least two evaporators. The flow rate of the compressor is modulated in response to the sensed temperature of the masses being cooled, and the control circuit switches valves to control the refrigerant flow path and modulates the flow rate of the compressor to optimize the efficiency of the refrigeration system.

Abstract: A piston end position limiter for a free piston machine of the type having a piston sealingly reciprocating in a cylinder and separating a work space bounded at one end of the piston from a second space bounded at the opposite end of the piston. The work space and the second space contain a working fluid having an average pressure. A first valve is connected in communication between a fluid reservoir and the work space and is adapted to open only when the working fluid pressure varies sufficiently in one direction from its average pressure. A second position responsive valve is connected between the reservoir and the second space and is operatively linked to the piston for opening in response to the piston reaching a selected end limit of its reciprocation.

Abstract: An improved mechanical transducer of the type having a body reciprocating in a chamber, the body being linked to a housing by a linkage including an axially compliant spring. An anti-friction fluid bearing applies a lateral centering force upon the body and a linkage component of the linkage has a lateral compliance sufficient for the centering forces exerted by the fluid bearing to at least equal the sum of lateral force exerted by the linkage and other lateral forces exerted upon the body. That lateral compliance allows the centering forces of the fluid bearing to be effective in moving the body away from the chamber wall and thereby minimize contact and consequent wear of the interfacing surfaces between the body and the chamber wall.