Abstract: A valve for use in a cracking process includes an erosion protection device. The erosion protection device includes at least one baffle projector beyond a contour of an inner wall of the closure part. The closure part is positioned between a first housing part and a second housing part. The expansion protection device minimizes the direct impact on the sealing surface and sealing seats of the value.

Abstract: A process and system for the computer-aided geometry modeling which makes possible a declarative, sequence-independent description of geometric shapes and geometric features and leads to an integrated modeling, which unites in itself geometric relationships and connects them with non-geometric information. To achieve this, the geometry-related information is represented in the form of a representation element, to which a density (.rho.) is assigned in the form of a real number. The linking of individual representation elements is performed by a single commutative and associative linking operation. A volume level, a topology level, and a generic area and edge level located between these levels are provided as the description levels for the actually relevant information. A feature level, at which features are defined and at which a knowledge-based system can be used, is located above these description levels.

Abstract: The present invention provides mice and mouse cell lines having a homozygous or heterozygous deficiency in a gene encoding a neurotrophin receptor. In a preferred embodiment of this invention, mice and cell lines carry a trkB locus specifically targeted within its tyrosine protein kinase sequences. Mice homozygous for this mutation express gp95.sup.trkB receptor of unknown function but not the high affinity functional gp145.sup.trkB tyrosine protein kinase receptors. This mutation results in multiple CNS and PNS neuronal deficiencies and in a postembryonic lethal phenotype. Such genetically modified mice are useful in model systems for studying human diseases involving neuronal degeneration and neuronal cell loss, as well as in screening for genes, proteins, or other compounds that may prevent or impede neuronal cell death or stimulate neuronal regeneration.

Abstract: Apparatus for the generation of compressed air includes a compressor, a motor for driving the compressor, a supply source of liquid lubricant for cooling the compressor, a storage container for the liquid lubricant, devices for separating the lubricant from the compressed air and for cooling the separated lubricant, and devices for controlling and regulating the procedures effected by the apparatus in the generation of the compressed air.