Abstract: Described here are devices, systems, and methods for closing the left atrial appendage. The methods described here utilize a closure device for closing the left atrial appendage and guides or expandable elements with ablation or abrading elements to ablate or abrade the left atrial appendage. In general, these methods include positioning a balloon at least partially within the atrial appendage, positioning a closure assembly of a closure device around an exterior of the atrial appendage, inflating the balloon, partially closing the closure assembly, ablating the interior tissue of the atrial appendage with the inflated balloon, removing the balloon from the atrial appendage, and closing the atrial appendage with the closure assembly.

Abstract: A thermally powered heat transfer system consisting of two closed heat transfer loops which share a compressor which is powered alternately by the refrigerants of the two loops. This system is powered by a single heat source with a portion of the heat from that heat source being transferred at a higher temperature to a structure to be heated, the balance being transferred to a low temperature external heat sink. The first loop includes an evaporator and the condenser within the structure to be heated, and is charged with a first refrigerant. The second loop includes an evaporator and a condenser located so as to transfer heat to an external heat sink. The second loop is charged with a refrigerant having a lower boiling point than the refrigerant in the first loop.