2,309 research outputs found
The ABACOC Algorithm: a Novel Approach for Nonparametric Classification of Data Streams
Stream mining poses unique challenges to machine learning: predictive models
are required to be scalable, incrementally trainable, must remain bounded in
size (even when the data stream is arbitrarily long), and be nonparametric in
order to achieve high accuracy even in complex and dynamic environments.
Moreover, the learning system must be parameterless ---traditional tuning
methods are problematic in streaming settings--- and avoid requiring prior
knowledge of the number of distinct class labels occurring in the stream. In
this paper, we introduce a new algorithmic approach for nonparametric learning
in data streams. Our approach addresses all above mentioned challenges by
learning a model that covers the input space using simple local classifiers.
The distribution of these classifiers dynamically adapts to the local (unknown)
complexity of the classification problem, thus achieving a good balance between
model complexity and predictive accuracy. We design four variants of our
approach of increasing adaptivity. By means of an extensive empirical
evaluation against standard nonparametric baselines, we show state-of-the-art
results in terms of accuracy versus model size. For the variant that imposes a
strict bound on the model size, we show better performance against all other
methods measured at the same model size value. Our empirical analysis is
complemented by a theoretical performance guarantee which does not rely on any
stochastic assumption on the source generating the stream
Measurement-induced quantum operations on multiphoton states
We investigate how multiphoton quantum states obtained through optical
parametric amplification can be manipulated by performing a measurement on a
small portion of the output light field. We study in detail how the macroqubit
features are modified by varying the amount of extracted information and the
strategy adopted at the final measurement stage. At last the obtained results
are employed to investigate the possibility of performing a
microscopic-macroscopic non-locality test free from auxiliary assumptions.Comment: 13 pages, 13 figure
Thermal Control of a Dual Mode Parametric Sapphire Transducer
We propose a method to control the thermal stability of a sapphire dielectric
transducer made with two dielectric disks separated by a thin gap and
resonating in the whispering gallery (WG) modes of the electromagnetic field.
The simultaneous measurement of the frequencies of both a WGH mode and a WGE
mode allows one to discriminate the frequency shifts due to gap variations from
those due to temperature instability. A simple model, valid in quasi
equilibrium conditions, describes the frequency shift of the two modes in terms
of four tuning parameters. A procedure for the direct measurement of them is
presented.Comment: 5 pages, 6 figures, presented at EFTF-IFCS joint conference 200
Anomalous resilient to decoherence macroscopic quantum superpositions generated by universally covariant optimal quantum cloning
We show that the quantum states generated by universal optimal quantum
cloning of a single photon represent an universal set of quantum superpositions
resilient to decoherence. We adopt Bures distance as a tool to investigate the
persistence ofquantum coherence of these quantum states. According to this
analysis, the process of universal cloning realizes a class of quantum
superpositions that exhibits a covariance property in lossy configuration over
the complete set of polarization states in the Bloch sphere.Comment: 8 pages, 6 figure
Magnetic Control of Transmission and Helicity of Nano-Structured Optical Beams in Magnetoplasmonic Vortex Lenses
We theoretically investigate the generation of far-field propagating optical
beams with a desired orbital angular momentum by using an archetypical
magnetoplasmonic tip surrounded by a gold spiral slit. The use of a magnetic
material can lead to important implications once magneto-optical activity is
activated through the application of an external magnetic field. The physical
model and the numerical study presented here introduce the concept of
magnetically tunable plasmonic vortex lens, namely a magnetoplasmonic vortex
lens, which ensures a tunable selectivity in the polarization state of the
generated nanostructured beam. The presented system provides a promising
platform for a localized excitation of plasmonic vortices followed by their
beaming in the far-field with an active modulation of both light's
transmittance and helicity
Anomalous lack of decoherence of the Macroscopic Quantum Superpositions based on phase-covariant Quantum Cloning
We show that all Macroscopic Quantum Superpositions (MQS) based on
phase-covariant quantum cloning are characterized by an anomalous high
resilence to the de-coherence processes. The analysis supports the results of
recent MQS experiments and leads to conceive a useful conjecture regarding the
realization of complex decoherence - free structures for quantum information,
such as the quantum computer.Comment: 4 pages, 3 figure
CRP Predicts Safe Patient Discharge after Colorectal Surgery. Reply
Reply: We would like to thank Aurelie´n Dupre`, Johan Gagnie´r, Heloı¨se Samba, Michel Rivoire, and Karem Slim for their comments about our article ‘‘Procalcitonin Reveals Early Dehiscence in Colorectal Surgery: The PREDICS Study.’’1 It is very rewarding to realize that this paper is stimulating so many observations, this means thatwe are talking about an interesting topic
Strength hierarchy provisions for transverse confinement systems of shell structural elements
Through-the-thickness (TT) confinement of masonry and concrete panels by composite
or steel reinforcements, aiming at seismic retrofit of existing structures, has recently
growth in popularity. However, structural design of transversal reinforcements, modeled
as an homogeneized material, is often performed by neglecting the cyclic nature
of seismic actions and by using static approaches. For this reason, a proper strength
hierarchy between the confined core material and the confining devices should be accounted
for in order to ensure that the retrofit system remains effective until the crisis
of the core material is attained. This research introduces strength hierarchy conditions
for TT-confinement systems, made of materials exhibiting a nonlinear behavior, aiming
at determining the minimum strength required for uniaxial confining devices. The
relevant relationships, theoretically derived by assuming a Drucker Prager constitutive
model for the confined material and by enforcing equilibrium and compatibility
conditions between the core and the confining devices, are characterized by simple
mechanical parameters, usually available in common practice applications, familiar to
most of the designers. Numerical examples confirm the effectiveness of the proposed
provisions
Switchable two-state plasmonic tweezers for dynamic manipulation of nano-objects
In this work we present a plasmonic platform capable of trapping nano-objects
as small as 100 nm in two different spatial configurations. The switch between
the two trapping states, localized on the tip and on the outer wall of a
vertical gold nanochannel, can be activated by a variation in the focusing
position of the excitation laser along the main axis of the nanotube. We show
that the trapping mechanism is facilitated by both an electromagnetic and
thermal action. The inner and outer trapping states are respectively
characterized by a static and a dynamic behavior and their stiffness was
measured by analyzing the position of the trapped specimens as a function of
time. In addition, it was demonstrated that the stiffness of the static state
is high enough to trap of particles as small as 40nm. These results show a
simple, controllable way to generate a switchable two-state trapping regime,
which could find applications as a model for the study of dynamic trapping or
as mechanism for the development of nanofluidic devices
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