Abstract: An installation for fabricating an optical fiber preform includes a reaction tube and an excess silica soot exhaust tube equipped internally with a screw having flat helical threads for removing the excess soot. The screw is a helix hollowed out longitudinally and the installation includes a cylinder housed within the interior passage of the helix, eccentrically disposed within this passage and bearing against the inside surface of the helix. The cylinder is rotated about its axis.

Abstract: Improved commercial single crystal wafers (250), as shipped to end users form a full circle, and comprise a "stress concentration notch" (172) which accurately defines a desired cleavage plane. The stress concentration notch is introduced into the wafers in bulk by means of a properly oriented cut along the length of a single crystal ingot, after machining the ingot to the desired end product diameter, and prior to sawing the ingot into slices. The stress concentration notch uniquely defines the first and second faces of the wafer.

Abstract: A magnetoresistive (MR) sensor having passive end regions separated by a central active region in which an MR sensing element is formed over substantially only the central active region. The MR sensor is defined by forming a resist pattern over both the end regions and the MR sensing element followed by an etching step where the duration of the etching is controlled by the time it takes to remove the exposed end regions' material and not by the time it takes to remove the excess MR material in the center active region. This creates an MR sensor having planar sides along the circumference of the end regions where the planar sides have no thinned edges or shoulders. The MR sensor further has no remnant MR material along the inner planar side of the end regions behind the MR sensor's trackwidth edge and adjacent to the MR sensor's back side.

Abstract: The channels through which ink flows to the firing chambers of an ink-jet printhead are provided with selectively controlled valves for restricting flow at specified times for reducing blowback from the firing chamber while decreasing the turn on energy of the printhead.