Abstract: Method and housing (2) for reducing particulate build-up on a surface of a device (5) contained in a recess (4) defined by the housing (2) when attached to a conduit. The method includes introducing gas into the recess (4) at a high volume and low velocity so that the gas flows in a laminar manner across the surface of the device (5). The volume lies in a range from 80 to 300 liters/minute and the velocity lies in a range from 0.2 to 3.6 meters/second. The method and housing (2) are particularly useful for preventing the build up of coal dust on the face of an ultrasonic transducer (5) used to measure the mass flow rate of coal being pneumatically transferred in the conduit.

Abstract: A gene sequence including a first promoter for the expression of a major early fowlpox virus (FPV) protein. In a preferred aspect, the gene sequence further includes a second promoter for the expression of a late fowlpox virus protein in opposite orientation to said first promoter. The promoter is useful in developing FPV based vectors for the delivery of vaccine antigens preferably to poultry, and as a tool to study the temporal regulation of poxvirus genes. The invention also offers methods useful in the construction of recombinant fowlpox viruses or related avian poxviruses, which methods are characterized by the introduction of foreign DNA into the fowlpox virus or into virus DNA sequences, which sequences are able to use native FPV promoter regions.