Abstract: In an embodiment, a method performed by a welding or cutting system having a power supply to supply weld power to an electrode tip extending from a welding torch, comprises: upon detecting a weld start condition, performing a start of weld procedure that includes sequential phases of controlling the weld power to strike an arc on a workpiece, grow a length of the arc to a target length, and heat the electrode tip and the workpiece until a weld energy supplied to the electrode tip across the sequential phases reaches a weld energy threshold indicative of a desired heat-related condition of the electrode tip and the workpiece for welding; and when the weld energy reaches the weld energy threshold, performing a welding operation on the workpiece.

Abstract: A method performed in a welding or cutting system configured to deliver weld power to an electrode tip extending from a torch to create an arc on a workpiece, comprises: sampling a sensed voltage indicative of a weld voltage provided to the electrode tip, to produce voltage values; computing a time derivative of the voltage values to produce voltage derivative values that represent a contact resistance between the electrode tip and the workpiece; and upon detecting a decrease in the voltage derivative values from above a time-derivative threshold to below the time-derivative threshold as an indication of a weld start event, increasing the weld power supplied to the electrode tip to initiate the arc on the workpiece.

Abstract: The present invention relates to a method and apparatus for growing cells in a three-dimensional scaffold. Relative movement of the scaffold and an end cap of the culture chamber results in circulation of the growth medium through the scaffold. The invention is also suited for introduction of cells into a scaffold. The scaffold may be any sort of natural or synthetic material that will support cellular life, including a tissue.

Abstract: As new compounds having .beta.-receptor blocking activity, isopropylamino-(pyridyloxy)-propanols with the general formula ##STR1## wherein R denotes hydrogen or amino. The compounds are prepared by reacting a corresponding 3-pyridinol with epichlorohydrin and the resulting product with isopropylamine.