5,993 research outputs found
Learning preferences for large scale multi-label problems
Despite that the majority of machine learning approaches aim to solve binary classification problems, several real-world applications require specialized algorithms able to handle many different classes, as in the case of single-label multi-class and multi-label classification problems. The Label Ranking framework is a generalization of the above mentioned settings, which aims to map instances from the input space to a total order over the set of possible labels. However, generally these algorithms are more complex than binary ones, and their application on large-scale datasets could be untractable. The main contribution of this work is the proposal of a novel general online preference-based label ranking framework. The proposed framework is able to solve binary, multi-class, multi-label and ranking problems. A comparison with other baselines has been performed, showing effectiveness and efficiency in a real-world large-scale multi-label task
Quantum correlations of twophoton polarization states in the parametric down-conversion process
We consider correlation properties of twophoton polarization states in the
parametric down-conversion process. In our description of polarization states
we take into account the simultaneous presence of colored and white noise in
the density matrix. Within the considered model we study the dependence of the
von Neumann entropy on the noise amount in the system and derive the
separability condition for the density matrix of twophoton polarization state,
using Perec-Horodecki criterion and majorization criterion. Then the dependence
of the Bell operator (in CHSH form) on noise is studied. As a result, we give a
condition for determining the presence of quantum correlation states in
experimental measurements of the Bell operator. Finally, we compare our
calculations with experimental data [doi:10.1103/PhysRevA.73.062110] and give a
noise amount estimation in the photon polarization state considered there.Comment: 10 pages, 7 figures; corrected typo
Investigation on dynamic behaviours of liquid and solid phases within non-homogeneous debris flows
The non-homogeneous debris flows, consisting of a wide range of grain size, bulk density and demonstrating non-uniform velocity distributions, are commonly modeled as the two-phase flow. In adopting such an approach, a critical grain diameter to separate the solid and liquid phase, within such debris flows, can be determined through the principles of minimum energy dissipation. In the current study, an improved analytical approach using the resistance formula of water flow and mass conservation law is presented to determine the velocity of the solid and liquid phases within a non-homogeneous debris flow, based on the derived critical grain diameter. Some of the dynamic parameters required in the analysis are validated against the experimental data of a non-homogeneous, two-phase debris flow measured from the Jiangjia gully, Yunnan Province of China. The results show that, for the majority of non-homogeneous debris flows tested, the liquid phase exhibits higher velocity than the solid phase. However, as the bulk density of the debris flow increases, the solid phase tends to have higher velocity than the liquid phase. These findings are shown to have important implications on the vertical grading patterns of the bed deposits in depositional areas. The observations from the field studies indicate that the non-homogeneous debris flows with bulk density being significantly lower, close to and significantly higher than the critical value seem to exhibit normal (i.e. bed-to-surface vertical fining), mixed, and inverse (bed-to-surface vertical coarsening) grading patterns in the alluvial fan deposits
Instability and Periodic Deformation in Bilayer Membranes Induced by Freezing
The instability and periodic deformation of bilayer membranes during freezing
processes are studied as a function of the difference of the shape energy
between the high and the low temperature membrane states. It is shown that
there exists a threshold stability condition, bellow which a planar
configuration will be deformed. Among the deformed shapes, the periodic curved
square textures are shown being one kind of the solutions of the associated
shape equation. In consistency with recent expe rimental observations, the
optimal ratio of period and amplitude for such a texture is found to be
approximately equal to (2)^{1/2}\pi.Comment: 8 pages in Latex form, 1 Postscript figure. To be appear in Mod.
Phys. Lett. B. 199
Demonstration of Temporal Distinguishability in a Four-Photon State and a Six-Photon State
An experiment is performed to demonstrate the temporal distinguishability of
a four-photon state and a six-photon state, both from parametric
down-conversion. The experiment is based on a multi-photon interference scheme
in a recent discovered NOON-state projection measurement. By measuring the
visibility of the interference dip, we can distinguish the various scenarios in
the temporal distribution of the pairs and thus quantitatively determine the
degree of temporal (in)distinguishability of a multi-photon state
Dimensional Crossover of Dilute Neon inside Infinitely Long Single-Walled Carbon Nanotubes Viewed from Specific Heats
A simple formula for coordinates of carbon atoms in a unit cell of a
single-walled nanotube (SWNT) is presented and the potential of neon (Ne)
inside an infinitely long SWNT is analytically derived under the assumption of
pair-wise Lennard-Jones potential between Ne and carbon atoms. Specific heats
of dilute Ne inside infinitely long (5, 5), (10, 10), (15, 15) and (20, 20)
SWNT's are calculated at different temperatures. It is found that Ne inside
four kinds of nanotubes exhibits 3-dimensional (3D) gas behavior at high
temperature but different behaviors at low temperature: Ne inside (5, 5)
nanotube behaves as 1D gas but inside (10, 10), (15, 15), and (20, 20)
nanotubes behaves as 2D gas. Furthermore, at ultra low temperature, Ne inside
(5, 5) nanotube still displays 1D behavior but inside (10, 10), (15, 15), and
(20, 20) nanotubes behaves as lattice gas.Comment: 10 pages, 5 figure
Electric Current Focusing Efficiency in Graphene Electric Lens
In present work, we theoretically study the electron wave's focusing
phenomenon in a single layered graphene pn junction(PNJ) and obtain the
electric current density distribution of graphene PNJ, which is in good
agreement with the qualitative result in previous numerical calculations
[Science, 315, 1252 (2007)]. In addition, we find that for symmetric PNJ, 1/4
of total electric current radiated from source electrode can be collected by
drain electrode. Furthermore, this ratio reduces to 3/16 in a symmetric
graphene npn junction. Our results obtained by present analytical method
provide a general design rule for electric lens based on negative refractory
index systems.Comment: 13 pages, 7 figure
Comment on ``Manipulating the frequency entangled states by an acoutic-optical modulator''
A recent theoretical paper [1] proposes a scheme for entanglement swapping
utilizing acousto-optic modulators without requiring a Bell-state measurement.
In this comment, we show that the proposal is flawed and no entanglement
swapping can occur without measurement.Comment: 6 pages, 2 figures submitted to Phys. Rev
Dynamic disorder in receptor-ligand forced dissociation experiments
Recently experiments showed that some biological noncovalent bonds increase
their lifetimes when they are stretched by an external force, and their
lifetimes will decrease when the force increases further. Several specific
quantitative models have been proposed to explain the intriguing transitions
from the "catch-bond" to the "slip-bond". Different from the previous efforts,
in this work we propose that the dynamic disorder of the force-dependent
dissociation rate can account for the counterintuitive behaviors of the bonds.
A Gaussian stochastic rate model is used to quantitatively describe the
transitions observed recently in the single bond P-selctin glycoprotein ligand
1(PSGL-1)P-selectin force rupture experiment [Marshall, {\it et al.}, (2003)
Nature {\bf 423}, 190-193]. Our model agrees well to the experimental data. We
conclude that the catch bonds could arise from the stronger positive
correlation between the height of the intrinsic energy barrier and the distance
from the bound state to the barrier; classical pathway scenario or {\it a
priori} catch bond assumption is not essential.Comment: 4 pages, 2 figure
Entanglement and interference between different degrees of freedom of photons states
In this paper, photonic entanglement and interference are described and
analyzed with the language of quantum information process. Correspondingly, a
photon state involving several degrees of freedom is represented in a new
expression based on the permutation symmetry of bosons. In this expression,
each degree of freedom of a single photon is regarded as a qubit and operations
on photons as qubit gates. The two-photon Hong-Ou-Mandel interference is well
interpreted with it. Moreover, the analysis reveals the entanglement between
different degrees of freedom in a four-photon state from parametric down
conversion, even if there is no entanglement between them in the two-photon
state. The entanglement will decrease the state purity and photon interference
visibility in the experiments on a four-photon polarization state.Comment: 11 pages and 2 figure
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