Large-aperture interferometer using local reference beam

A large-aperture interferometer was devised by adding a local-reference-beam-generating optical system to a schlieren system. Two versions of the interferometer are demonstrated, one employing 12.7 cm (5 in.) diameter schlieren optics, the other employing 30.48 cm (12 in.) diameter parabolic mirrors in an off-axis system. In the latter configuration a cylindrical lens is introduced near the light source to correct for astigmatism. A zone plate is a satisfactory decollimating element in the reference-beam arm of the interferometer. Attempts to increase the flux and uniformity of irradiance in the reference beam by using a diffuser are discussed

Neural coding of high-frequency tones

Available evidence was presented indicating that neural discharges in the auditory nerve display characteristic periodicities in response to any tonal stimulus including high-frequency stimuli, and that this periodicity corresponds to the subjective pitch

Optical elements formed by compressed gases: Analysis and potential applications

Spherical, cylindrical, and conical shock waves are optically analogous to gas lenses. The geometrical optics of these shock configurations are analyzed as they pertain to flow visualization instruments, particularly the rainbow schlieren apparatus and single-pass interferometers. It is proposed that a lens or mirror formed by gas compressed between plastic sheets has potential as a fluid visualization test object; as the objective mirror in a very large space-based telescope, communication antenna, or energy collector; as the objective mirror in inexpensive commercial telescopes; and as a component in fluid visualization apparatuses

Rainbow Schlieren

The rainbow schlieren is an apparatus in which the usual schlieren knife edge cutoff is replaced by a radial rainbow filter with a transparent center and an opaque surround. With this apparatus most refractive index nonuniformities in the test section appear varicolored whereas uniformities appear white. The rainbow schlieren is simple, easy to use, and relatively inexpensive and gives much greater detail regarding nonuniformities than does the ordinary schlieren. Moreover, the rainbow schlieren permits quantitative evaluation of certain refractive index distributions, including those involving turbulence, by simple calculations

Loudness (annoyance), prediction procedure for steady sounds

Method has been devised to predict loudness level of any steady sound solely from its measured power spectrum level. Method is based on assumption that, with respect to loudness sensation, the human auditory system acts as open-loop transmission system with transmittance function determined from measured tone curves

The Q parables of the mustard seed and leaven : half‐baked and garden‐variety metaphors?

Abstract: The parables of the Mustard Seed and Leaven have received countless interpretations over the years. Out of these, interpretations that relate these parables to categories of either impurity or growth (but also contrast) predominate. This article will critically evaluate these approaches before proposing a novel avenue of interpretation

‘I do not know you!’ : reconsidering the redaction of Q 13:25-27

Abstract: In The Formation of Q, Kloppenborg identifies three redactional layers in the Sayings Gospel Q: the ‘formative stratum’ (or Q¹), the ‘main redaction’ (or Q²), and the ‘final recension’ (or Q³). He ascribes Q 13:25-27 in its entirety to the main redaction. As an alternative, it will presently be argued that verse 25 belongs to the formative stratum, while verses 26-27 belong to the main redaction. To substantiate the preceding case, verse 25 will be measured against Kloppenborg’s own criteria for distinguishing between the formative stratum and the main redaction, namely those of ‘characteristic forms’, ‘characteristic motifs’ and ‘implied audience’

Negotiating identities and emotional belonging: Shan in northern Thailand

This paper explores the complex ways in which Burmese Shan migrants in Northern Thailand utilise strategic practices of in/visibility and in/audibility to maintain emotional attachments to ethnic identity and belonging while negotiating a double exclusion from national belonging and citizenship in both home and host countries. Fleeing Shan State as a result of the long standing civil war and gross human rights abuses by Burma’s military junta, over 200,000 Shan have entered Thailand since 1996. Based on research conducted among three Shan communities in the small town of Pai, this article examines how strategic deployment and concealment of ethnic identity – in/visibility and in/audibility – allows Shan migrants to navigate different spaces of safety and precariousness while located in a situation of permanent temporariness of national (non)belonging