27,299 research outputs found
Anomalously small wave tails in higher dimensions
We consider the late-time tails of spherical waves propagating on
even-dimensional Minkowski spacetime under the influence of a long range radial
potential. We show that in six and higher even dimensions there exist
exceptional potentials for which the tail has an anomalously small amplitude
and fast decay. Along the way we clarify and amend some confounding arguments
and statements in the literature of the subject.Comment: 13 page
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Toward a taxonomic model of attention in effortful listening
In recent years, there has been increasing interest in studying listening effort. Research on listening effort intersects with the development of active theories of speech perception and contributes to the broader endeavor of understanding speech perception within the context of neuroscientific theories of perception, attention, and effort. Due to the multidisciplinary nature of the problem, researchers vary widely in their precise conceptualization of the catch-all term listening effort. Very recent consensus work stresses the relationship between listening effort and the allocation of cognitive resources, providing a conceptual link to current cognitive neuropsychological theories associating effort with the allocation of selective attention. By linking listening effort to attentional effort, we enable the application of a taxonomy of external and internal attention to the characterization of effortful listening. More specifically, we use a vectorial model to decompose the demand causing listening effort into its mutually orthogonal external and internal components and map the relationship between demanded and exerted effort by means of a resource-limiting term that can represent the influence of motivation as well as vigilance and arousal. Due to its quantitative nature and easy graphical interpretation, this model can be applied to a broad range of problems dealing with listening effort. As such, we conclude that the model provides a good starting point for further research on effortful listening within a more differentiated neuropsychological framework
The Geoff Egan Memorial Lecture 2011. Artefacts, art and artifice: reconsidering iconographic sources for archaeological objects in early modern Europe
A first systematic analysis of historic domestic material culture depicted in contemporaneous Western painting and prints, c.1400-1800. Drawing on an extensive data set, the paper proposes to methodologies and hermeneutics for historical analysis and archaeological correspondence
Representation of Quantum Mechanical Resonances in the Lax-Phillips Hilbert Space
We discuss the quantum Lax-Phillips theory of scattering and unstable
systems. In this framework, the decay of an unstable system is described by a
semigroup. The spectrum of the generator of the semigroup corresponds to the
singularities of the Lax-Phillips -matrix. In the case of discrete (complex)
spectrum of the generator of the semigroup, associated with resonances, the
decay law is exactly exponential. The states corresponding to these resonances
(eigenfunctions of the generator of the semigroup) lie in the Lax-Phillips
Hilbert space, and therefore all physical properties of the resonant states can
be computed.
We show that the Lax-Phillips -matrix is unitarily related to the
-matrix of standard scattering theory by a unitary transformation
parametrized by the spectral variable of the Lax-Phillips theory.
Analytic continuation in has some of the properties of a method
developed some time ago for application to dilation analytic potentials.
We work out an illustrative example using a Lee-Friedrichs model for the
underlying dynamical system.Comment: Plain TeX, 26 pages. Minor revision
An exploration into the client at the heart of therapy : a qualitative perspective
Over 50 years ago Eysenck challenged the existing base of research into psychotherapy. Since that time, a large number of investigations have been conducted to verify the efficacy of therapy. Recently however, an increasing number of studies have cast new doubts on this research base. Instead of therapy being a function of the therapist, it is now becoming ever more apparent that the client plays a prime role in the therapeutic process. The qualitative studies presented in this paper provide some examples of research that demonstrates that clients are actively involved in their therapy, even making counselling work despite their counsellor. These studies suggest that clients may not experience therapy as beneficially as traditional outcome studies indicate. This raises a new challenge to researchers to more fully explore the client's experience of therapy, a challenge to which qualitative methods of inquiry would appear well suited
Searching For Integrated Sachs-Wolfe Effect Beyond Temperature Anisotropies: CMB E-mode Polarization-Galaxy Cross Correlation
The cross-correlation between cosmic microwave background (CMB) temperature
anisotropies and the large scale structure (LSS) traced by the galaxy
distribution, or sources at different wavelengths, is now well known. This
correlation results from the integrated Sachs-Wolfe (ISW) effect in CMB
anisotropies generated at late times due to the dark energy component of the
Universe. In a reionized universe, the ISW quadrupole rescatters and
contributes to the large-scale polarization signal. Thus, in principle, the
large-scale polarization bump in the E-mode should also be correlated with the
galaxy distribution. Unlike CMB temperature-LSS correlation that peaks for
tracers at low redshifts this correlation peaks mostly at redshifts between 1
and 3. Under certain conditions, mostly involving a low optical depth to
reionization, if the Universe reionized at a redshift around 6, the cross
polarization-source signal is marginally detectable, though challenging as it
requires all-sky maps of the large scale structure at redshifts between 1 and
3. If the Universe reionized at a redshift higher than 10, it is unlikely that
this correlation will be detectable even with no instrumental noise all-sky
maps. While our estimates do not guarantee a detection unknown physics related
to the dark energy as well as still uncertain issues related to the large
angular scale CMB and polarization anisotropies may motivate attempts to
measure this correlation using upcoming CMB polarization E-mode maps.Comment: 13 pages; 3 figure panels, JCAP submitte
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