3,777 research outputs found

    Tonal prisms: iterated quantization in chromatic tonality and Ravel's 'Ondine'

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    The mathematics of second-order maximal evenness has far-reaching potential for application in music analysis. One of its assets is its foundation in an inherently continuous conception of pitch, a feature it shares with voice-leading geometries. This paper reformulates second-order maximal evenness as iterated quantization in voice-leading spaces, discusses the implications of viewing diatonic triads as second-order maximally even sets for the understanding of nineteenth-century modulatory schemes, and applies a second-order maximally even derivation of acoustic collections in an in-depth analysis of Ravel's ‘Ondine’. In the interaction between these two very different applications, the paper generalizes the concepts and analytical methods associated with iterated quantization and also pursues a broader argument about the mutual dependence of mathematical music theory and music analysis.Accepted manuscrip

    The momentum spectrum of nuclear active particles in the cosmic radiation

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    This thesis describes studies of nuclear active particles (NAPs) in the cosmic radiation over the momentum range 1-30 GeV/c. Both unaccompanied particles and NAPs in extensive air showers (EAS) are studied near sea level at Durham using an air-gap magnet spectrograph in conjunction with a neutron monitor. Details are given of the design of the spectrograph, neutron monitor and associated equipment as used for measurements on unaccompanied NAPs (Chapter 2), and the techniques used for derivation of the momentum spectra from the basic data are described in Chapter 3. The results, in the form of momentum spectra of unaccompanied protons and negative pions, and the limited analysis of NAPs in EAS are presented in Chapter 4 where they are compared with the results of other workers. Measurements of the momentum of NAPs in EAS were found to be difficult and the data are mainly concerned with the response of the neutron monitor to EAS. A model of the propagation of cosmic rays through the atmosphere, which was mainly intended for predictions of the properties of large EAS, is described and used to predict the momentum spectra of unaccompanied particles at sea level. The results of this prediction are compared with the experimental data (Chapter 5) and the results of other model predictions (Chapter 6). It is shown that no single model, when combined with a reasonable spectrum of primary cosmic rays, can adequately explain all the data on unaccompanied particles at sea level. It is also shown that the spectra of high energy protons and pions are likely to be the sea level measurements which are most sensitive to the form of the primary cosmic ray spectrum

    Study of cryogenic fluid mixing techniques. Volume 2 - Large-scale mixing data Final report, Jul. 1969 - Jul. 1970

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    Basic mixing data and dimensionless correlations for 52 tests in large-scale stratified mixing tank for cryogenic rocket propellant

    A study of cryogenic propellant mixing techniques. Volume 1 - Mixer design and experimental investigations Final report, Jul. 1967 - Sep. 1968

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    Mixer design and experimental tank study for cryogenic propellants, with applications for manned Mars missio

    Time Dilation and Quasar Variability

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    The timescale of quasar variability is widely expected to show the effects of time dilation. In this paper we analyse the Fourier power spectra of a large sample of quasar light curves to look for such an effect. We find that the timescale of quasar variation does not increase with redshift as required by time dilation. Possible explanations of this result all conflict with widely held consensus in the scientific community.Comment: 6 pages including 3 figures. Accepted for publication in ApJ Letter

    Deconvolution with correct sampling

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    A new method for improving the resolution of astronomical images is presented. It is based on the principle that sampled data cannot be fully deconvolved without violating the sampling theorem. Thus, the sampled image should not be deconvolved by the total Point Spread Function, but by a narrower function chosen so that the resolution of the deconvolved image is compatible with the adopted sampling. Our deconvolution method gives results which are, in at least some cases, superior to those of other commonly used techniques: in particular, it does not produce ringing around point sources superimposed on a smooth background. Moreover, it allows to perform accurate astrometry and photometry of crowded fields. These improvements are a consequence of both the correct treatment of sampling and the recognition that the most probable astronomical image is not a flat one. The method is also well adapted to the optimal combination of different images of the same object, as can be obtained, e.g., from infrared observations or via adaptive optics techniques.Comment: 22 pages, LaTex file + 10 color jpg and postscript figures. To be published in ApJ, Vol 484 (1997 Feb.

    A Synoptic, Multiwavelength Analysis of a Large Quasar Sample

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    We present variability and multi-wavelength photometric information for the 933 known quasars in the QUEST Variability Survey. These quasars are grouped into variable and non-variable populations based on measured variability confidence levels. In a time-limited synoptic survey, we detect an anti-correlation between redshift and the likelihood of variability. Our comparison of variability likelihood to radio, IR, and X-ray data is consistent with earlier quasar studies. Using already-known quasars as a template, we introduce a light curve morphology algorithm that provides an efficient method for discriminating variable quasars from periodic variable objects in the absence of spectroscopic information. The establishment of statistically robust trends and efficient, non-spectroscopic selection algorithms will aid in quasar identification and categorization in upcoming massive synoptic surveys. Finally, we report on three interesting variable quasars, including variability confirmation of the BL Lac candidate PKS 1222+037.Comment: AJ, accepted for publication 15 Dec 200

    Influence of Normal Daytime Fat Deposition on Laboratory Measurements of Torpor Use in Territorial versus Nonterritorial Hummingbirds

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    Fat deposition and torpor use in hummingbirds exhibiting distinct foraging styles should vary. We predicted that dominant territorial hummingbirds will use torpor less than subordinate nonterritorial species because unrestricted access to energy by territory owners allows for fat storage. Entry into torpor was monitored using open-flow respirometry on hummingbirds allowed to accumulate fat normally during the day. Fat accumulation was measured by solvent fat extraction. Territorial blue-throated hummingbirds (Lampornis clemenciae) had the highest fat accumulation and used torpor only 17% of the time. Fat storage by L. clemenciae averaged 26% of lean dry mass (LDM) in 1995 and 18% in 1996, similar to that measured for other nonmigratory birds. Fat storage by magnificent hummingbirds (Eugenes fulgens; trapliner) and black-chinned hummingbirds (Archilochus alexandri; nectar robber) averaged 19% and 16% of LDM, respectively, and they used torpor frequently (64% and 92% of the time, respectively). All species initiated torpor if total body fat dropped below 10% of LDM, indicating the existence of a torpor threshold. The ability of L. clemenciae to store enough fat to support nighttime metabolism is likely an important benefit of territoriality. Likewise, frequent torpor use by subordinates suggests that natural restrictions to energy intake can impact their energy budget, necessitating energy conservation by use of torpor

    Decontextualizing contextual inversion

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    Contextual inversion, introduced as an analytical tool by David Lewin, is a concept of wide reach and value in music theory and analysis, at the root of neo-Riemannian theory as well as serial theory, and useful for a range of analytical applications. A shortcoming of contextual inversion as it is currently understood, however, is, as implied by the name, that the transformation has to be defined anew for each application. This is potentially a virtue, requiring the analyst to invest the transformational system with meaning in order to construct it in the first place. However, there are certainly instances where new transformational systems are continually redefined for essentially the same purposes. This paper explores some of the most common theoretical bases for contextual inversion groups and considers possible definitions of inversion operators that can apply across set class types, effectively decontextualizing contextual inversions.Accepted manuscrip
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