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In order to further improve the output power of W-band traveling wave tube (TWT), a low gain TWT was proposed as a secondary amplifier. It uses a double staggered grating slow wave structure (DSG-S...

In this paper we evaluate experimentally measured signal-to-noise ratio performance of different types of optical amplifiers [V. Josse, M. Sabuncu, N. Cerf, et al., Phys. Rev. Lett. 96 163602 (2006); Z.Y. Ou, S.F. Pereira and H.J. Kimble, Phys. Rev. Lett. 70 3239 (1993)]. We pay particular attention to the low gain regime where the quantum limit of the amplifier varies with gain. Independent of the amplifier type the noise performance is remarkably close to the quantum limit. Low gain optical amplifiers are of interest for quantum communication.

The smooth pursuit eye tracking deficit (ETD) often associated with schizophrenia has generated enormous interest over the last 20 years. The deficit is observed in about 80% of schizophrenics and in half of their first degree relatives. It is not affected by neuroleptic medication and is not due to inattention. A review of 52 studies (and actual records when available) on ETD in schizophrenia reveals that the deficit can consistently be described as low gain pursuit augmented with catch-up saccades and often peppered with intrusive saccades. A review of the brain areas that have been shown to be involved in pursuit provides the necessary background for the subsequent section which details the nature of the smooth tracking deficits following experimental lesions. This section reveals that the ETD following lesions of the frontal lobe is unique in that it closely resembles the ETD of schizophrenics. This finding lends further support for frontal lobe theories of schizophrenia.

The objective of this study was to assess the ease of handling, comfort, and general effectiveness of three types of earmould in patients who, due to their age, could be expected to experience handling difficulties. The three mould types were, meatal tip, skeleton and skeleton with the 'top prong' removed. The results indicated that the skeleton with the top prong removed was the best in all contexts but one. It was easiest and quickest to fit and least likely to be badly fitted. Only in feedback control did it perform less well. It was concluded that it should be routinely used for elderly patients fitted with low gain hearing aids.

The relationship between pupil-gains in oral language development and the classroom behaviour ofmikilyretaixiedspedal class pupilj and their teachers was examinedmtwo studies. In Study 1 it was (bund that the children from classes which made high gains in receptive oral language spent more time in reading and writing activities and less time listening to the teacher, than those from low gain classes, but the classroom behaviour of the teachers of high and low gain classes did not seem noticeably different In Study 2, a contrast was drawn between classes in which children had made high gains in expressive oral language development and those where the children had made low gains. The children from high gain classes spent less time in structured/teacher-directed language activities than did children from low gain classes, and the teachers of the high gain classes spent less than half the time shown by teachers of tow gain classes in interacting with the observed children. The results of the two studies are d...

This paper presents a frequency-domain based input-output theory of multivariable low-gain Pl-control of infinite-dimensional stable systems. It is known that under very mild assumptions a large class of infinite-dimensional systems can be stabilized and regulated by multivariable Pl-controUers with sufficiently low gain. The controller design can be accomplished using plant step data only. No other knowledge of the plant is required. The application of the input-output results to distributed parameter systems and neutral systems is discussed.

A type of ring antenna has been studied for applications on satellite in sub-orbital as well as in orbital flight, in view of realizing a small sized structure and a low gain. Admittance properties and radiation patterns are given together with indications for a proper designing of the antenna.

The paper describes the design of a Fresnel zone plate suitable for use as an antenna in the centimetric or lower wavelength range. It has been shown that such antennas can be fabricated by using either metal or dielectric rings. Its properties have been analysed by employing the simple methods of electromagnetic diffraction. Experimental results are reported showing close agreement with the theory. A theory has been presented explaining the working of the dielectric ring zone plate. The investigation leads to the conclusion that both the metal and dielectric zone plates are useful as low gain antennas.