160,493 research outputs found
MFM-Net: Unpaired Shape Completion Network with Multi-stage Feature Matching
Unpaired 3D object completion aims to predict a complete 3D shape from an
incomplete input without knowing the correspondence between the complete and
incomplete shapes during training. To build the correspondence between two data
modalities, previous methods usually apply adversarial training to match the
global shape features extracted by the encoder. However, this ignores the
correspondence between multi-scaled geometric information embedded in the
pyramidal hierarchy of the decoder, which makes previous methods struggle to
generate high-quality complete shapes. To address this problem, we propose a
novel unpaired shape completion network, named MFM-Net, using multi-stage
feature matching, which decomposes the learning of geometric correspondence
into multi-stages throughout the hierarchical generation process in the point
cloud decoder. Specifically, MFM-Net adopts a dual path architecture to
establish multiple feature matching channels in different layers of the
decoder, which is then combined with the adversarial learning to merge the
distribution of features from complete and incomplete modalities. In addition,
a refinement is applied to enhance the details. As a result, MFM-Net makes use
of a more comprehensive understanding to establish the geometric correspondence
between complete and incomplete shapes in a local-to-global perspective, which
enables more detailed geometric inference for generating high-quality complete
shapes. We conduct comprehensive experiments on several datasets, and the
results show that our method outperforms previous methods of unpaired point
cloud completion with a large margin
Visualizing the Quantum Interaction Picture in Phase Space
We illustrate the correspondence between the quantum Interaction
Picture-evolution of the state of a quantum system in Hilbert space and a
combination of local and global transformations of its Wigner function in phase
space. To this aim, we consider the time-evolution of a quantized harmonic
oscillator driven by both a linear and a quadratic (in terms of bosonic
creation and annihilation operators) potentials and employ the Magnus series to
derive the exact form of the time-evolution operator. In this case, the
Interaction Picture corresponds to a local transformation of phase
space-reference frame into the one that is co-moving with the Wigner function.Comment: Submitted to New Journal of Physic
Mediating boundaries between knowledge and knowing: ICT and R4D praxis
Research for development (R4D) praxis (theory-informed practical action) can be underpinned by the use of Information and Communication Technologies (ICTs) which, it is claimed, provide opportunities for knowledge working and sharing. Such a framing implicitly or explicitly constructs a boundary around knowledge as reified, or commodified â or at least able to be stabilized for a period of time (first order knowledge). In contrast âthird-generation knowledgeâ emphasizes the social nature of learning and knowledge-making; this reframes knowledge as a negotiated social practice, thus constructing a different system boundary. This paper offers critical reflections on the use of a wiki as a data repository and mediating technical platform as part of innovating in R4D praxis. A sustainable social learning process was sought that fostered an emergent community of practice among biophysical and social researchers acting for the first time as R4D co-researchers. Over time the technologically mediated element of the learning system was judged to have failed. This inquiry asks: How can learning system design cultivate learning opportunities and respond to learning challenges in an online environment to support R4D practice? Confining critical reflection to the online learning experience alone ignores the wider context in which knowledge work took place; therefore the institutional setting is also considered
Methodological issues in national-comparative research on cultural tastes : the case of cultural capital in the UK and Finland
Drawing on two projects which develop the methodological model of Bourdieuâs Distinction in the UK and Finland, this paper explores the issues raised by the use of multiple correspondence analysis (MCA) and mixed methods in comparative work on cultural tastes. By identifying the problems in the construction of two comparable yet nationally relevant research instruments, the paper considers the importance of the similarities and differences in the meaning of items in different national spaces for Bourdieu-inspired comparative analysis. The paper also reports on the evident similarities between the two constructed spaces and draws on the dialogue between quantitative and qualitative methods enabled by MCA in examining what different positions in social space appear to mean in these countries country. It concludes by suggesting that, whilst Bourdieuâs model provides a robust set of methods for exploring relations between taste and class within nations, used appropriately, it can also provide particular insight to the comparison between national fields
Bondi-Metzner-Sachs symmetry, holography on null-surfaces and area proportionality of "light-slice" entropy
It is shown that certain kinds of behavior, which hitherto were expected to
be characteristic for classical gravity and quantum field theory in curved
spacetime, as the infinite dimensional Bondi-Metzner-Sachs symmetry, holography
on event horizons and an area proportionality of entropy, have in fact an
unnoticed presence in Minkowski QFT. This casts new light on the fundamental
question whether the volume propotionality of heat bath entropy and the
(logarithmically corrected) dimensionless area law obeyed by
localization-induced thermal behavior are different geometric parametrizations
which share a common primordeal algebraic origin. Strong arguments are
presented that these two different thermal manifestations can be directly
related, this is in fact the main aim of this paper. It will be demonstrated
that QFT beyond the Lagrangian quantization setting receives crucial new
impulses from holography onto horizons. The present paper is part of a project
aimed at elucidating the enormous physical range of "modular localization". The
latter does not only extend from standard Hamitonian heat bath thermal states
to thermal aspects of causal- or event- horizons addressed in this paper. It
also includes the recent understanding of the crossing property of formfactors
whose intriguing similarity with thermal properties was, although sometimes
noticed, only sufficiently understood in the modular llocalization setting.Comment: 42 pages, changes, addition of new results and new references, in
this form the paper will appear in Foundations of Physic
Death and Lightness: Using a Demographic Model to Find Support Verbs
Some verbs have a particular kind of binary ambiguity: they can carry their
normal, full meaning, or they can be merely acting as a prop for the nominal
object. It has been suggested that there is a detectable pattern in the
relationship between a verb acting as a prop (a \term{support verb}) and the
noun it supports.
The task this paper undertakes is to develop a model which identifies the
support verb for a particular noun, and by extension, when nouns are
enumerated, a model which disambiguates a verb with respect to its support
status. The paper sets up a basic model as a standard for comparison; it then
proposes a more complex model, and gives some results to support the model's
validity, comparing it with other similar approaches.Comment: LaTeX, 8 pages, uses aclap.st
Holographic Gravitational Anomalies
In the AdS/CFT correspondence one encounters theories that are not invariant
under diffeomorphisms. In the boundary theory this is a gravitational anomaly,
and can arise in 4k+2 dimensions. In the bulk, there can be gravitational
Chern-Simons terms which vary by a total derivative. We work out the
holographic stress tensor for such theories, and demonstrate agreement between
the bulk and boundary. Anomalies lead to novel effects, such as a nonzero
angular momentum for global AdS(3). In string theory such Chern-Simons terms
are known with exact coefficients. The resulting anomalies, combined with
symmetries, imply corrections to the Bekenstein-Hawking entropy of black holes
that agree exactly with the microscopic counting.Comment: 25 page
Composite Higgs under LHC Experimental Scrutiny
The LHC has been built to understand the dynamics at the origin of the
breaking of the electroweak symmetry. Weakly coupled models with a fundamental
Higgs boson have focused most of the attention of the experimental searches. We
will discuss here how to reinterpret these searches in the context of strongly
coupled models where the Higgs boson emerges as a composite particle. In
particular, we use LHC data to constrain the compositeness scale. We also
briefly review the prospects to observe other bosonic and fermionic resonances
of the strong sector.Comment: 6 pages. Contribution to the proceedings of Hadron Collider Physics
Symposium 2011, Paris Nov. 14-1
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