7,969 research outputs found
Spatial coherence of forward-scattered light in a turbid medium
We study spatially coherent forward-scattered light propagating in a turbid medium of moderate optical depth (0-9 mean free paths). Coherent detection was achieved by using a tilted heterodyne geometry, which desensitizes coherent detection of the attenuated incident light. We show that the degree of spatial coherence is significantly higher for light scattered only once in comparison with that for multiply scattered light and that it approaches a small constant value for large numbers of scattering events
A two-dimensional Fermi liquid with attractive interactions
We realize and study an attractively interacting two-dimensional Fermi
liquid. Using momentum resolved photoemission spectroscopy, we measure the
self-energy, determine the contact parameter of the short-range interaction
potential, and find their dependence on the interaction strength. We
successfully compare the measurements to a theoretical analysis, properly
taking into account the finite temperature, harmonic trap, and the averaging
over several two-dimensional gases with different peak densities
Loudly sing cuckoo : More-than-human seasonalities in Britain
This research was funded by a grant from the Arts and Humanities Research Council, grant number AH/E009573/1.Peer reviewedPostprin
Questioning acoustemology: an interview with Steven Feld
This is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this record.In this conversation transcript, Tom Rice asks Steve Feld a series of questions
about ‘acoustemology’, a term Steve coined and which has become a key concept
in sound studies. Referring to ‘acoustic epistemology’, a ‘knowing-with and
knowing-through the audible’, acoustemology emerged in the context of Steve’s
work on the Kaluli of Papua New Guinea and their intricate knowledge of the
sounds of their rainforest environment (Feld 2015, 12). It has since been applied
by Steve, and many others, in studies of sound in a wide variety of settings. Tom
asks questions that have arisen as he tries to explore and clarify the implications
of the term. For instance, are acoustemologies invariably culturally embedded, or
can they also be understood to emerge independently of culture? To what extent
are acoustemologies shaped by individual and personal preferences, experiences
and abilities? Is it possible for one acoustemology to end and another begin or do
acoustemologies merely shift in terms of the sounds to which they are orientated?
Answering with illustrations from his own intellectual journey, Steve presents
acoustemology as an open-ended concept which is generative rather than
prescriptive and which invites ongoing empirical research and interdisciplinary
discussio
Gravity a la Born-Infeld
A simple technique for the construction of gravity theories in Born-Infeld
style is presented, and the properties of some of these novel theories are
investigated. They regularize the positive energy Schwarzschild singularity,
and a large class of models allows for the cancellation of ghosts. The possible
correspondence to low energy string theory is discussed. By including curvature
corrections to all orders in alpha', the new theories nicely illustrate a
mechanism that string theory might use to regularize gravitational
singularities.Comment: 21 pages, 2 figures, new appendix B with corrigendum: Class. Quantum
Grav. 21 (2004) 529
Pure functions in C: A small keyword for automatic parallelization
© 2020, The Author(s). The need for parallel task execution has been steadily growing in recent years since manufacturers mainly improve processor performance by increasing the number of installed cores instead of scaling the processor’s frequency. To make use of this potential, an essential technique to increase the parallelism of a program is to parallelize loops. Several automatic loop nest parallelizers have been developed in the past such as PluTo. The main restriction of these tools is that the loops must be statically analyzable which, among other things, disallows function calls within the loops. In this article, we present a seemingly simple extension to the C programming language which marks functions without side-effects. These functions can then basically be ignored when the automatic parallelizer checks the parallelizability of loops. We integrated the approach into the GCC compiler toolchain and evaluated it by running several real-world applications. Our experiments show that the C extension helps to identify additional parallelization opportunities and, thus, to significantly increase the performance of applications
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