38,391 research outputs found
Symmetry-breaking phase-transitions in highly concentrated semen
New experimental evidence of self-motion of a confined active suspension is presented. Depositing fresh semen sample in an annular shaped micro- fluidic chip leads to a spontaneous vortex state of the fluid at sufficiently large sperm concentration. The rotation occurs unpredictably clockwise or counterclockwise and is robust and stable. Furthermore, for highly active and concentrated semen, richer dynamics can occur such as self-sustained or damped rotation oscillations. Experimental results obtained with systematic dilution provide a clear evidence of a phase transition toward collective motion associated with local alignment of spermatozoa akin to the Vicsek model. A macroscopic theory based on previously derived Self-Organized Hydrodynamics (SOH) models is adapted to this context and provides predictions consistent with the observed stationary motion
Interactions between a massless tensor field with the mixed symmetry of the Riemann tensor and a massless vector field
Consistent couplings between a massless tensor field with the mixed symmetry
of the Riemann tensor and a massless vector field are analyzed in the framework
of Lagrangian BRST cohomology. Under the assumptions on smoothness, locality,
Lorentz covariance, and Poincare invariance of the deformations, combined with
the requirement that the interacting Lagrangian is at most second-order
derivative, it is proved that there are no consistent cross-interactions
between a single massless tensor field with the mixed symmetry of the Riemann
tensor and one massless vector field.Comment: LaTeX, 24 page
Chaotic behaviors of a digital filter with two’s complement arithmetic and arbitrary initial conditions and order
This letter shows some counter-intuitive simulation results that the symbolic sequences and the state variables of a digital filter with two’s complement arithmetic and arbitrary initial conditions and order will be eventually zero when all the filter parameters are even numbers, no matter the system matrix of the filter is stable or not
Effective Hamiltonian Approach to the Master Equation
A method of exactly solving the master equation is presented in this letter.
The explicit form of the solution is determined by the time evolution of a
composite system including an auxiliary system and the open system in question.
The effective Hamiltonian governing the time evolution of the composed system
are derived from the master equation. Two examples, the dissipative two-level
system and the damped harmonic oscillator, are presented to illustrate the
solving procedure.
PACS number(s): 05.30.-d, 05.40.+j, 42.50.CtComment: 4 pages, no figure
N-Soliton Solutions to a New (2 + 1) Dimensional Integrable Equation
We give explicitly N-soliton solutions of a new (2 + 1) dimensional equation,
. This equation is obtained by unifying two
directional generalization of the KdV equation, composing the closed ring with
the KP equation and Bogoyavlenskii-Schiff equation. We also find the Miura
transformation which yields the same ring in the corresponding modified
equations.Comment: 7 pages, uses ioplppt.st
Iterative Segmentation from Limited Training Data: Applications to Congenital Heart Disease
We propose a new iterative segmentation model which can be accurately learned
from a small dataset. A common approach is to train a model to directly segment
an image, requiring a large collection of manually annotated images to capture
the anatomical variability in a cohort. In contrast, we develop a segmentation
model that recursively evolves a segmentation in several steps, and implement
it as a recurrent neural network. We learn model parameters by optimizing the
interme- diate steps of the evolution in addition to the final segmentation. To
this end, we train our segmentation propagation model by presenting incom-
plete and/or inaccurate input segmentations paired with a recommended next
step. Our work aims to alleviate challenges in segmenting heart structures from
cardiac MRI for patients with congenital heart disease (CHD), which encompasses
a range of morphological deformations and topological changes. We demonstrate
the advantages of this approach on a dataset of 20 images from CHD patients,
learning a model that accurately segments individual heart chambers and great
vessels. Com- pared to direct segmentation, the iterative method yields more
accurate segmentation for patients with the most severe CHD malformations.Comment: Presented at the Deep Learning in Medical Image Analysis Workshop,
MICCAI 201
A new metric for rotating charged Gauss-Bonnet black holes in AdS spaces
This paper presents a new metric for slowly rotating charged Gauss-Bonnet
black holes in higher dimensional anti-de Sitter spaces. Taking the angular
momentum parameter up to second order, the slowly rotating charged black
hole solutions are obtained by working directly in the action.Comment: 11 pages and accepted by Chin. Phys.
Point-contact study of the LuNi2B2C borocarbide superconducting film
We present point-contact (PC) Andreev-reflection measurements of a
superconducting epitaxial c-axis oriented nickel borocarbide film LuNi2B2C
(Tc=15.9 K). The averaged value of the superconducting gap is found to be 2.6
+/-0.2 meV in the one-gap approach, whereas the two-gap approach results in
2.14+/-0.36 meV and 3.0+/-0.27 meV. The better fit of the Andreev-reflection
spectra for the LuNi2B2C - Cu PC obtained by the two-gap approach provides
evidence for multiband superconductivity in LuNi2B2C. For the first time, PC
electron-phonon interaction (EPI) spectra have been measured for this compound.
They demonstrate pronounced phonon maximum at 8.5+/-0.4meV and a second shallow
one at 15.8+/-0.6 meV. The electron-phonon coupling constant estimated from the
PC EPI spectra turned out to be small (~ 0.1), like in other superconducting
rare-earth nickel borocarbides. Possible reasons for this are discussed.Comment: 5 pages, 5 figures, V2: figs. 2 & 5 captions are corrected, and new
Refs. 4, 6, 12, 13, 14 are adde
- …