16,216 research outputs found
A New Look at the Schouten-Nijenhuis, Fr\"olicher-Nijenhuis and Nijenhuis-Richardson Brackets for Symplectic Spaces
In this paper we re-express the Schouten-Nijenhuis, the Fr\"olicher-Nijenhuis
and the Nijenhuis-Richardson brackets on a symplectic space using the extended
Poisson brackets structure present in the path-integral formulation of
classical mechanics.Comment: 27+1 pages, Latex, no figure
Identifying Emotions in Social Media: Comparison of Word-emotion lexica
In recent years, emotions expressed in social media messages have become a vivid research topic due to their influence on the spread of misinformation and online radicalization over online social networks. Thus, it is important to correctly identify emotions in order to make inferences from social media messages. In this paper, we report on the performance of three publicly available word-emotion lexicons (NRC, DepecheMood, EmoSenticNet) over a set of Facebook and Twitter messages. To this end, we designed and implemented an algorithm that applies natural language processing (NLP) techniques along with a number of heuristics that reflect the way humans naturally assess emotions in written texts. In order to evaluate the appropriateness of the obtained emotion scores, we conducted a questionnaire-based survey with human raters. Our results show that there are noticeable differences between the performance of the lexicons as well as with respect to emotion scores the human raters provided in our surve
Detecting Gaussian entanglement via extractable work
We show how the presence of entanglement in a bipartite Gaussian state can be
detected by the amount of work extracted by a continuos variable Szilard-like
device, where the bipartite state serves as the working medium of the engine.
We provide an expression for the work extracted in such a process and
specialize it to the case of Gaussian states. The extractable work provides a
sufficient condition to witness entanglement in generic two-mode states,
becoming also necessary for squeezed thermal states. We extend the protocol to
tripartite Gaussian states, and show that the full structure of inseparability
classes cannot be discriminated based on the extractable work. This suggests
that bipartite entanglement is the fundamental resource underpinning work
extraction.Comment: 12 pages, 8 figure
Non-equilibrium readiness and accuracy of Gaussian Quantum Thermometers
The dimensionality of a thermometer is key in the design of quantum
thermometry schemes. In general, the phenomenology that is typical of
finite-dimensional quantum thermometry does not apply to infinite dimensional
ones. We analyse the dynamical and metrological features of non-equilibrium
Gaussian Quantum Thermometers: on one hand, we highlight how quantum
entanglement can enhance the readiness of composite Gaussian thermometers; on
the other hand, we show that non-equilibrium conditions do not guarantee the
best sensitivities in temperature estimation, thus suggesting the reassessment
of the working principles of quantum thermometry
The insider on the outside: a novel system for the detection of information leakers in social networks
Confidential information is all too easily leaked by naive users posting comments. In this paper we introduce DUIL, a system for Detecting Unintentional Information Leakers. The value of DUIL is in its ability to detect those responsible for information leakage that occurs through comments posted on news articles in a public environment, when those articles have withheld material non-public information. DUIL is comprised of several artefacts, each designed to analyse a different aspect of this challenge: the information, the user(s) who posted the information, and the user(s) who may be involved in the dissemination of information. We present a design science analysis of DUIL as an information system artefact comprised of social, information, and technology artefacts. We demonstrate the performance of DUIL on real data crawled from several Facebook news pages spanning two years of news articles
Nonlinearity and nonclassicality in a nanomechanical resonator
We address quantitatively the relationship between the nonlinearity of a
mechanical resonator and the nonclassicality of its ground state. In
particular, we analyze the nonclassical properties of the nonlinear Duffing
oscillator (being driven or not) as a paradigmatic example of a nonlinear
nanomechanical resonator. We first discuss how to quantify the nonlinearity of
this system and then show that the nonclassicality of the ground state, as
measured by the volume occupied by the negative part of the Wigner function,
monotonically increases with the nonlinearity in all the working regimes
addressed in our study. Our results show quantitatively that nonlinearity is a
resource to create nonclassical states in mechanical systems.Comment: 6 pages; 7 figures; RevTeX4-
Little-Parks oscillations near a persistent current loop
We investigate the Little-Parks oscillations caused by a persistent current
loop set on the top edge of a mesoscopic superconducting thin-walled cylinder
with a finite height. For a short cylinder the Little-Parks oscillations are
approximately the same ones as the standard effect, as there is only one
magnetic flux piercing the cylinder. For a tall cylinder the inhomogeneity of
the magnetic field makes different magnetic fluxes pierce the cylinder at
distinct heights and we show here that this produces two distinct Little-Parks
oscillatory regimes according to the persistent current loop. We show that
these two regimes, and also the transition between them, are observable in
current measurements done in the superconducting cylinder. The two regimes stem
from different behavior along the height, as seen in the order parameter,
numerically obtained from the Ginzburg-Landau theory through the finite element
methodComment: 13 pages, 12 figure
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