3,246 research outputs found
TandemNet: Distilling Knowledge from Medical Images Using Diagnostic Reports as Optional Semantic References
In this paper, we introduce the semantic knowledge of medical images from
their diagnostic reports to provide an inspirational network training and an
interpretable prediction mechanism with our proposed novel multimodal neural
network, namely TandemNet. Inside TandemNet, a language model is used to
represent report text, which cooperates with the image model in a tandem
scheme. We propose a novel dual-attention model that facilitates high-level
interactions between visual and semantic information and effectively distills
useful features for prediction. In the testing stage, TandemNet can make
accurate image prediction with an optional report text input. It also
interprets its prediction by producing attention on the image and text
informative feature pieces, and further generating diagnostic report
paragraphs. Based on a pathological bladder cancer images and their diagnostic
reports (BCIDR) dataset, sufficient experiments demonstrate that our method
effectively learns and integrates knowledge from multimodalities and obtains
significantly improved performance than comparing baselines.Comment: MICCAI2017 Ora
Self-consistent simulations of a von K\'arm\'an type dynamo in a spherical domain with metallic walls
We have performed numerical simulations of boundary-driven dynamos using a
three-dimensional non-linear magnetohydrodynamical model in a spherical shell
geometry. A conducting fluid of magnetic Prandtl number Pm=0.01 is driven into
motion by the counter-rotation of the two hemispheric walls. The resulting flow
is of von K\'arm\'an type, consisting of a layer of zonal velocity close to the
outer wall and a secondary meridional circulation. Above a certain forcing
threshold, the mean flow is unstable to non-axisymmetric motions within an
equatorial belt. For fixed forcing above this threshold, we have studied the
dynamo properties of this flow. The presence of a conducting outer wall is
essential to the existence of a dynamo at these parameters. We have therefore
studied the effect of changing the material parameters of the wall (magnetic
permeability, electrical conductivity, and thickness) on the dynamo. In common
with previous studies, we find that dynamos are obtained only when either the
conductivity or the permeability is sufficiently large. However, we find that
the effect of these two parameters on the dynamo process are different and can
even compete to the detriment of the dynamo. Our self-consistent approach allow
us to analyze in detail the dynamo feedback loop. The dynamos we obtain are
typically dominated by an axisymmetric toroidal magnetic field and an axial
dipole component. We show that the ability of the outer shear layer to produce
a strong toroidal field depends critically on the presence of a conducting
outer wall, which shields the fluid from the vacuum outside. The generation of
the axisymmetric poloidal field, on the other hand, occurs in the equatorial
belt and does not depend on the wall properties.Comment: accepted for publication in Physical Review
Deep Multi-instance Networks with Sparse Label Assignment for Whole Mammogram Classification
Mammogram classification is directly related to computer-aided diagnosis of
breast cancer. Traditional methods rely on regions of interest (ROIs) which
require great efforts to annotate. Inspired by the success of using deep
convolutional features for natural image analysis and multi-instance learning
(MIL) for labeling a set of instances/patches, we propose end-to-end trained
deep multi-instance networks for mass classification based on whole mammogram
without the aforementioned ROIs. We explore three different schemes to
construct deep multi-instance networks for whole mammogram classification.
Experimental results on the INbreast dataset demonstrate the robustness of
proposed networks compared to previous work using segmentation and detection
annotations.Comment: MICCAI 2017 Camera Read
Excitation of inertial modes in a closed grid turbulence experiment under rotation
We report an experimental study of the decay of grid-generated turbulence in
a confined geometry submitted to a global rotation. Turbulence is generated by
rapidly towing a grid in a parallelepipedic water tank. The velocity fields of
a large number of independent decays are measured in a vertical plane parallel
to the rotation axis using a corotating Particle Image Velocimetry system. We
first show that, when a "simple" grid is used, a significant amount of the
kinetic energy (typically 50%) is stored in a reproducible flow composed of
resonant inertial modes. The spatial structure of those inertial modes,
extracted by band-pass filtering, is found compatible with the numerical
results of Maas [Fluid Dyn. Res. 33, 373 (2003)]. The possible coupling between
these modes and turbulence suggests that turbulence cannot be considered as
freely decaying in this configuration. Finally, we demonstrate that these
inertial modes may be significantly reduced (down to 15% of the total energy)
by adding a set of inner tanks attached to the grid. This suggests that it is
possible to produce an effectively freely decaying rotating turbulence in a
confined geometry
Coriolis force in Geophysics: an elementary introduction and examples
We show how Geophysics may illustrate and thus improve classical Mechanics
lectures concerning the study of Coriolis force effects. We are then interested
in atmospheric as well as oceanic phenomena we are familiar with, and are for
that reason of pedagogical and practical interest. Our aim is to model them in
a very simple way to bring out the physical phenomena that are involved.Comment: Accepted for publication in European Journal of Physic
Recommended from our members
Association of Prenatal Urinary Concentrations of Phthalates and Bisphenol A and Pubertal Timing in Boys and Girls.
BackgroundAnimal studies suggest that phthalates and bisphenol A (BPA), endocrine-disrupting chemicals found in many consumer products, may impact the timing of puberty.ObjectivesWe aimed to determine the association of prenatal exposure to high-molecular-weight phthalates and BPA with pubertal timing in boys and girls participating in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) longitudinal cohort study.MethodsWe quantified urinary concentrations of eight phthalate metabolites and BPA at two time points during pregnancy among participating mothers ([Formula: see text]) and conducted clinical Tanner staging of puberty on their children every 9 months between 9 and 13 y of age. We conducted accelerated failure time models and examined the role of child overweight/obese status in this association.ResultsThe sum of urinary metabolites of di(2-ethylhexyl) phthalate [Formula: see text], monobenzyl phthalate (MBzP), and BPA were associated with later onset of at least one of the three outcomes assessed in girls (thelarche, pubarche, or menarche) and with earlier onset of at least one of the two outcomes assessed in boys (gondarche and pubarche). We found that monocarboxynonyl phthalate, monocarboxyoctyl phthalate, mono(3-carboxypropyl) phthalate, and BPA were associated with later pubarche and menarche mostly among normal-weight girls but not overweight/obese girls. MBzP was associated with later thelarche in all girls, and [Formula: see text] was associated with later thelarche and menarche in all girls. BPA and all phthalate biomarkers were associated with earlier gonadarche and pubarche in all boys as well as in overweight/obese boys when stratified by weight. Among normal-weight boys, associations with BPA were also inverse, whereas associations with phthalate metabolites were close to the null or positive.ConclusionsSeveral high-molecular-weight phthalates and BPA were associated with later puberty in girls and earlier puberty in boys included in the CHAMACOS cohort study. Childhood overweight/obesity may modify these associations. https://doi.org/10.1289/EHP3424
Super Stability of Laminar Vortex Flow in Superfluid 3He-B
Vortex flow remains laminar up to large Reynolds numbers (Re~1000) in a
cylinder filled with 3He-B. This is inferred from NMR measurements and
numerical vortex filament calculations where we study the spin up and spin down
responses of the superfluid component, after a sudden change in rotation
velocity. In normal fluids and in superfluid 4He these responses are turbulent.
In 3He-B the vortex core radius is much larger which reduces both surface
pinning and vortex reconnections, the phenomena, which enhance vortex bending
and the creation of turbulent tangles. Thus the origin for the greater
stability of vortex flow in 3He-B is a quantum phenomenon. Only large flow
perturbations are found to make the responses turbulent, such as the walls of a
cubic container or the presence of invasive measuring probes inside the
container.Comment: 4 pages, 6 figure
Self Running Droplet: Emergence of Regular Motion from Nonequilibrium Noise
Spontaneous motion of an oil droplet driven by chemical nonequilibricity is
reported. It is shown that the droplet undergoes regular rhythmic motion under
appropriately designed boundary conditions, whereas it exhibits random motion
in an isotropic environment. This study is a novel manifestation on the direct
energy transformation of chemical energy into regular spatial-motion under
isothermal conditions. A simple mathematical equation including noise
reproduces the essential feature of the transition from irregularity into
periodic regular motion. Our results will inspire the theoretical study on the
mechanism of molecular motors in living matter, working under significant
influence of thermal fluctuation.Comment: 4 pages, 4 figure
The decay of turbulence in rotating flows
We present a parametric space study of the decay of turbulence in rotating
flows combining direct numerical simulations, large eddy simulations, and
phenomenological theory. Several cases are considered: (1) the effect of
varying the characteristic scale of the initial conditions when compared with
the size of the box, to mimic "bounded" and "unbounded" flows; (2) the effect
of helicity (correlation between the velocity and vorticity); (3) the effect of
Rossby and Reynolds numbers; and (4) the effect of anisotropy in the initial
conditions. Initial conditions include the Taylor-Green vortex, the
Arn'old-Beltrami-Childress flow, and random flows with large-scale energy
spectrum proportional to . The decay laws obtained in the simulations for
the energy, helicity, and enstrophy in each case can be explained with
phenomenological arguments that separate the decay of two-dimensional from
three-dimensional modes, and that take into account the role of helicity and
rotation in slowing down the energy decay. The time evolution of the energy
spectrum and development of anisotropies in the simulations are also discussed.
Finally, the effect of rotation and helicity in the skewness and kurtosis of
the flow is considered.Comment: Sections reordered to address comments by referee
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