19,772 research outputs found
Toward an ecological conception of timbre
This paper is part of a series in which we had worked in the last 6 months, and, specifically, intend to investigate the notion of timbre through the ecological perspective proposed by James Gibson in his Theory of Direct Perception. First of all, we discussed the traditional approach to timbre, mainly as developed in acoustics and psychoacoustics. Later, we proposed a new conception of timbre that was born in concepts of ecological approach.
The ecological approach to perception proposed by Gibson (1966, 1979) presupposes a level of analysis of perceptual stimulated that includes, but is quite broader than the usual physical aspect. Gibson suggests as focus the relationship between the perceiver and his environment. At the core of this approach, is the notion of affordances, invariant combinations of properties at the ecological level, taken with reference to the anatomy and action systems of species or individual, and also with reference to its biological and social needs. Objects and events are understood as relates to a perceiving organism by the meaning of structured information, thus affording possibilities of action by the organism.
Event perception aims at identifying properties of events to specify changes of the environment that are relevant to the organism. The perception of form is understood as a special instance of event perception, which is the identity of an object depends on the nature of the events in which is involved and what remains invariant over time. From this perspective, perception is not in any sense created by the brain, but is a part of the world where information can be found. Consequently, an ecological approach represents a form of direct realism that opposes the indirect realist based on predominant approaches to perception borrowed from psychoacoustics and computational approach
Floquet engineering of optical solenoids and quantized charge pumping along tailored paths in two-dimensional Chern insulators
The insertion of a local magnetic flux, as the one created by a thin
solenoid, plays an important role in gedanken experiments of quantum Hall
physics. By combining Floquet engineering of artificial magnetic fields with
the ability of single-site addressing in quantum-gas microscopes, we propose a
scheme for the realization of such local solenoid-type magnetic fields in
optical lattices. We show that it can be employed to manipulate and probe
elementary excitations of a topological Chern insulator. This includes
quantized adiabatic charge pumping along tailored paths inside the bulk, as
well as the controlled population of edge modes.Comment: 6 pages, 4 figures. Discussions and references are update
Parsing as Reduction
We reduce phrase-representation parsing to dependency parsing. Our reduction
is grounded on a new intermediate representation, "head-ordered dependency
trees", shown to be isomorphic to constituent trees. By encoding order
information in the dependency labels, we show that any off-the-shelf, trainable
dependency parser can be used to produce constituents. When this parser is
non-projective, we can perform discontinuous parsing in a very natural manner.
Despite the simplicity of our approach, experiments show that the resulting
parsers are on par with strong baselines, such as the Berkeley parser for
English and the best single system in the SPMRL-2014 shared task. Results are
particularly striking for discontinuous parsing of German, where we surpass the
current state of the art by a wide margin
“The Right to the City” An Ecosystemic Approach to Better Cities, Better Life
Urbanism is a focus on cities and urban areas, their geography, economies, politics, social characteristics, as well as the effects on, and caused by, the built environment; it is linked to various aspects of quality of life: education, culture, justice, labour, environment, health, safety, housing, leisure, transport, consumption. This year, the United Nations proposed the following questions for the citizens of the world: What is the best thing about your city? What's the worst thing about your city? What do you want the authorities to do about it? What can you do about it? It is a clear attempt to foster civic participation and personal engagement, but to make things happen it is necessary to create active socio-cultural niches at many societal levels.Urbanism; politics; education; culture; justice
Overview of Constrained PARAFAC Models
In this paper, we present an overview of constrained PARAFAC models where the
constraints model linear dependencies among columns of the factor matrices of
the tensor decomposition, or alternatively, the pattern of interactions between
different modes of the tensor which are captured by the equivalent core tensor.
Some tensor prerequisites with a particular emphasis on mode combination using
Kronecker products of canonical vectors that makes easier matricization
operations, are first introduced. This Kronecker product based approach is also
formulated in terms of the index notation, which provides an original and
concise formalism for both matricizing tensors and writing tensor models. Then,
after a brief reminder of PARAFAC and Tucker models, two families of
constrained tensor models, the co-called PARALIND/CONFAC and PARATUCK models,
are described in a unified framework, for order tensors. New tensor
models, called nested Tucker models and block PARALIND/CONFAC models, are also
introduced. A link between PARATUCK models and constrained PARAFAC models is
then established. Finally, new uniqueness properties of PARATUCK models are
deduced from sufficient conditions for essential uniqueness of their associated
constrained PARAFAC models
The influence of information availability on the choice of destination
We set a framework where an individual has to choose one among a set of spatially distributed activities. The individual knows the price of each activity, as well as the distance to reach it. She has either full or zero information about each activity's quality. Qualities are modeled by i.i.d. random variables. Under the full information regime, the individual knows the realizations of the qualities; while under the no information regime, she only knows the distribution of the qualities. In that case, she can decide either ex ante, or en route, how many activities to patronize. We analyze the impact of information availability on the choice process, on the distance the individual covers, and on the individual's expected utility. In this framework, more information yields longer distance traveled, but also higher utility. We compute the individual's willingness to pay for information. Finally, we show that providing information may decrease the individual's benefit when congestion arises.travel demand, search, logit, information regimes, value of information, differentiation
Hopf characterization of two-dimensional Floquet topological insulators
We present a topological characterization of time-periodically driven
two-band models in 2+1 dimensions as Hopf insulators. The intrinsic periodicity
of the Floquet system with respect to both time and the underlying
two-dimensional momentum space constitutes a map from a three dimensional torus
to the Bloch sphere. As a result, we find that the driven system can be
understood by appealing to a Hopf map that is directly constructed from the
micromotion of the drive. Previously found winding numbers are shown to
correspond to Hopf invariants, which are associated with linking numbers
describing the topology of knots in three dimensions. Moreover, after being
cast as a Hopf insulator, not only the Chern numbers, but also the winding
numbers of the Floquet topological insulator become accessible in experiments
as linking numbers. We exploit this description to propose a feasible scheme
for measuring the complete set of their Floquet topological invariants in
optical lattices.Comment: 6 pages, 3 figures + 2 pages, 1 figure supplementar
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