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1. There are two classes of theories of Universal Grammar: (1) Formalist theories, such as the widespread varieties of generative grammar. These theories start from the assumption that certain strings of linguistic forms are grammatical while other strings are ungrammatical. A grammar of this type produces grammatical strings and does not produce ungrammatical ones. All theories of this class fail in the same respect: they do not account for the meaning of the strings. (2) Semiotactic theories, which describe the meaning of a string in terms of the meanings of its constituent forms and their interrelations. The only elaborate formalized theory of this class presently available is the one advanced by C.L. Ebeling (Syntax and Semantics, Leiden: Brill, 1978). I shall discuss some of its mathematical properties here.
To reach high luminosities in future linear colliders short range wakes havea to be controlled in the range of X-band frequencies or higher. Rectangular irises can be used to introduce strong focusing quadrupole-like rf-fields. Even circular irises in iris-loaded accelarator structures have the capability of focusing if the particle velocity differs from phase velocity. Theoretical investigations concerning the focusing strength to be expected are presented. Their applicability for linear colliders is discussed.
A new method of measuring quality factors in cavities is presented. This method is well suited to measure quality factors in undamped cavities as well as in heavily damped cavities, and in addition this method provides a possibility of separating modes and measuring quality factors especially in cases of overlapping modes. Measurements have been carried out on HOM-damped cavities for the DESY/THD linear collider project. Results are presented.
Damping cells for the higher order modes are necessary for the S-band linear collider to minimize BBU (Beam-Break-Up). The construction of the damper cells has to take into account the different field geometries of the higher order modes. So two different types of dampers have been designed: a wall slotted an an iris slotted cell. In order to optimize the two types of damping cells with respect to damping strength, impedance matching between coupling system and waveguide dampers and between damping cell and undamped cells and the tuning system, damping cells of both types have been built and examinated.