Abstract: A system includes a surface device, preferably positioned on a surface, a downhole device, and a wireline communications system. A downlink communication between the surface device and the downhole device occurs via Hopped Frequency Shift Keying (HFSK) voltage-modulated signals. An optional uplink communication between the downhole device and the surface device may occur via Frequency Shift Keying (FSK) current-modulated signals. The downhole device may comprise an addressable switch.

Abstract: A gun tube for a downhole perforating gun assembly includes a body having a cavity and one or more weights in the cavity. Gravity acts on the weights, which causes the tube body to rotate around its longitudinal axis so the weights are adjacent the lower part of the wellbore in which the gun assembly is positioned when oriented horizontally. This positions shape charges in the gun tube in a desired position prior to the shape charges being fired. The gun tube may also include one or more end connectors with electrical contacts having a first, extended position, and a second, contracted position, and/or end connectors that can be assembled by hand without the use of tools.

Abstract: A gun tube for a downhole perforating gun assembly includes a body, a first end, and a second end. A motor is directly or indirectly attached to one or both of the ends and is configured to rotate the gun tube around its longitudinal axis in order to position shape charges in the gun tube in a desired position before firing the shape charges. A sensor may be on the gun tube, a sub-assembly, or an outer casing to detect the relative position of the shape charges and a signal including the position of the shape charges could be sent to a human or machine operator.

Abstract: A high molecular weight polysaccharide intracellular adhesin (SAE) antigen having the general structure of poly-1,6,?-2-amidoglucopyranoside, which is variable substituted with N-acetyl and O-succinyl substituents is described. Also, a method is given for isolating this antigen from Staphylococcus aureus. The SAE can be used in a vaccine, either alone, conjugated to an immunogenic protein, and/or with an immunogenic adjuvant.