270 research outputs found
Sound archaeology: terminology, Palaeolithic cave art and the soundscape
This article is focused on the ways that terminology describing the study of music and sound within archaeology has changed over time, and how this reflects developing methodologies, exploring the expectations and issues raised by the use of differing kinds of language to define and describe such work. It begins with a discussion of music archaeology, addressing the problems of using the term âmusicâ in an archaeological context. It continues with an examination of archaeoacoustics and acoustics, and an emphasis on sound rather than music. This leads on to a study of sound archaeology and soundscapes, pointing out that it is important to consider the complete acoustic ecology of an archaeological site, in order to identify its affordances, those possibilities offered by invariant acoustic properties. Using a case study from northern Spain, the paper suggests that all of these methodological approaches have merit, and that a project benefits from their integration
Field-induced breakdown of the quantum Hall effect
A numerical analysis is made of the breakdown of the quantum Hall effect
caused by the Hall electric field in competition with disorder. It turns out
that in the regime of dense impurities, in particular, the number of localized
states decreases exponentially with the Hall field, with its dependence on the
magnetic and electric field summarized in a simple scaling law. The physical
picture underlying the scaling law is clarified. This intra-subband process,
the competition of the Hall field with disorder, leads to critical breakdown
fields of magnitude of a few hundred V/cm, consistent with observations, and
accounts for their magnetic-field dependence \propto B^{3/2} observed
experimentally. Some testable consequences of the scaling law are discussed.Comment: 7 pages, Revtex, 3 figures, to appear in Phys. Rev.
Quantum railroads and directed localization at the juncture of quantum Hall systems
The integer quantum Hall effect (QHE) and one-dimensional Anderson
localization (AL) are limiting special cases of a more general phenomenon,
directed localization (DL), predicted to occur in disordered one-dimensional
wave guides called "quantum railroads" (QRR). Here we explain the surprising
results of recent measurements by Kang et al. [Nature 403, 59 (2000)] of
electron transfer between edges of two-dimensional electron systems and
identify experimental evidence of QRR's in the general, but until now entirely
theoretical, DL regime that unifies the QHE and AL. We propose direct
experimental tests of our theory.Comment: 11 pages revtex + 3 jpeg figures, to appear in Phys. Rev.
Integer Quantum Hall Effect with Realistic Boundary Condition : Exact Quantization and Breakdown
A theory of integer quantum Hall effect(QHE) in realistic systems based on
von Neumann lattice is presented. We show that the momentum representation is
quite useful and that the quantum Hall regime(QHR), which is defined by the
propagator in the momentum representation, is realized. In QHR, the Hall
conductance is given by a topological invariant of the momentum space and is
quantized exactly. The edge states do not modify the value and topological
property of in QHR. We next compute distribution of current based
on effective action and find a finite amount of current in the bulk and the
edge, generally. Due to the Hall electric field in the bulk, breakdown of the
QHE occurs. The critical electric field of the breakdown is proportional to
and the proportional constant has no dependence on Landau levels in
our theory, in agreement with the recent experiments.Comment: 48 pages, figures not included, some additions and revision
The dawn of the dead : (improbable) art after aI-zombie apocalypse
In recent years there has been growing interest in artificial neural networks (ANNs) which are quickly becoming the primary device for machine learning. Used for finding patterns in large data sets, ANNs were also recently employed in many artistic contexts: as tools for artists, semi-independent creators of content, and even as invisible "critics" which / who predict our aesthetic preferences. The aim of this paper is to speculate about the disruptive effect of these âalien agenciesâ on the (modernist) aesthetic regime of art centred around the notion of autonomy. The author examines how neural networks and connectionist epistemologies may potentially affect the most common ways of producing, circulating, and valorising art. He claims that the possibility of automatizing creativity and art criticism may lead to the emergence of a new aesthetic regime based on forms of dynamic, distributed and probabilistic governance
Sonorous memory in Jonathan Perelâs El predio (2010) and Los murales (2011)
Throughout his filmic production, Argentine director Jonathan Perel has demonstrated strict adherence to a unique aesthetic programme in which human agents appear to have only a minimal role. Each film contains only diegetic sounds and consists of fixed shots of architectural spaces and objects closely associated with the most recent Argentine military dictatorship (1976â1983) and recent attempts to memorialise the atrocities they committed. Through the close analysis of Perelâs first two films â El predio (2010) and Los murales (2011) â this article focusses on Perelâs highly distinctive use of environmental sound and argues that they are, in fact, uniquely musical works. Drawing on the work of John Cage, Michel Chion, Deleuze and Guattari, and Doreen Massey, the article proposes that Perel manipulates sound in order to situate debates over the memorialisation of recent atrocities in a perpetual present and thus critique contemporary abuses of power in Argentina
Strong, Ultra-narrow Peaks of Longitudinal and Hall Resistances in the Regime of Breakdown of the Quantum Hall Effect
With unusually slow and high-resolution sweeps of magnetic field, strong,
ultra-narrow (width down to ) resistance peaks are observed in
the regime of breakdown of the quantum Hall effect. The peaks are dependent on
the directions and even the history of magnetic field sweeps, indicating the
involvement of a very slow physical process. Such a process and the sharp peaks
are, however, not predicted by existing theories. We also find a clear
connection between the resistance peaks and nuclear spin polarization.Comment: 5 pages with 3 figures. To appear in PR
Improved Theory of the Muonium Hyperfine Structure
Terms contributing to the hyperfine structure of the muonium ground state at
the level of few tenths of kHz have been evaluated. The
radiative correction has been calculated numerically to the precision of 0.02
kHz. Leading terms of order and some relativistic corrections have been evaluated analytically.
The theoretical uncertainty is now reduced to 0.17 kHz. At present, however, it
is not possible to test QED to this precision because of the 1.34 kHz
uncertainty due to the muon mass.Comment: 11 pages + 2 figures (included), RevTeX 3.0, CLNS 94/127
Thermohydrodynamics in Quantum Hall Systems
A theory of thermohydrodynamics in two-dimensional electron systems in
quantizing magnetic fields is developed including a nonlinear transport regime.
Spatio-temporal variations of the electron temperature and the chemical
potential in the local equilibrium are described by the equations of
conservation with the number and thermal-energy flux densities. A model of
these flux densities due to hopping and drift processes is introduced for a
random potential varying slowly compared to both the magnetic length and the
phase coherence length. The flux measured in the standard transport experiment
is derived and is used to define a transport component of the flux density. The
equations of conservation can be written in terms of the transport component
only. As an illustration, the theory is applied to the Ettingshausen effect, in
which a one-dimensional spatial variation of the electron temperature is
produced perpendicular to the current.Comment: 10 pages, 1 figur
What 4âČ33âł Is
What is John Cage's 4âČ33âł? This paper disambiguates this question into three sub-questions concerning, respectively, the work's ontological nature, the art form to which it belongs, and the genre it is in. We shall see that the work's performances consist of silence (rather than containing environmental sounds), that it is a work of performance art (rather than music), and that it belongs to the genre of conceptual art. Seeing the work in these ways helps us to understand it better, and promises to assuage somewhat the puzzlement and irritation of those who are at first resistant to its charms
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