2,916 research outputs found
Efficient Active Learning for Image Classification and Segmentation using a Sample Selection and Conditional Generative Adversarial Network
Training robust deep learning (DL) systems for medical image classification
or segmentation is challenging due to limited images covering different disease
types and severity. We propose an active learning (AL) framework to select most
informative samples and add to the training data. We use conditional generative
adversarial networks (cGANs) to generate realistic chest xray images with
different disease characteristics by conditioning its generation on a real
image sample. Informative samples to add to the training set are identified
using a Bayesian neural network. Experiments show our proposed AL framework is
able to achieve state of the art performance by using about 35% of the full
dataset, thus saving significant time and effort over conventional methods
Modeling the Field Emission Current Fluctuation in Carbon Nanotube Thin Films
Owing to their distinct properties, carbon nanotubes (CNTs) have emerged as
promising candidate for field emission devices. It has been found
experimentally that the results related to the field emission performance show
variability. The design of an efficient field emitting device requires the
analysis of the variabilities with a systematic and multiphysics based modeling
approach. In this paper, we develop a model of randomly oriented CNTs in a thin
film by coupling the field emission phenomena, the electron-phonon transport
and the mechanics of single isolated CNT. A computational scheme is developed
by which the states of CNTs are updated in time incremental manner. The device
current is calculated by using Fowler-Nordheim equation for field emission to
study the performance at the device scale.Comment: 4 pages, 5 figure
From Type IIA Black Holes to T-dual Type IIB D-Instantons in N=2, D=4 Supergravity
We discuss the T-duality between the solutions of type IIA versus IIB
superstrings compactified on Calabi-Yau threefolds. Within the context of the
N=2, D=4 supergravity effective Lagrangian, the T-duality transformation is
equivalently described by the c-map, which relates the special Kahler moduli
space of the IIA N=2 vector multiplets to the quaternionic moduli space of the
N=2 hyper multiplets on the type IIB side (and vice versa). Hence the
T-duality, or c-map respectively, transforms the IIA black hole solutions,
originating from even dimensional IIA branes, of the special Kahler effective
action, into IIB D-instanton solutions of the IIB quaternionic sigma-model
action, where the D-instantons can be obtained by compactifying odd IIB
D-branes on the internal Calabi-Yau space. We construct via this mapping a
broad class of D-instanton solutions in four dimensions which are determinded
by a set of harmonic functions plus the underlying topological Calabi-Yau data.Comment: LaTeX, 37 pages. Some typos fixed. Final version, to appear in Nucl.
Phys.
Gauged symmetry, fourth generation, neutrino mass and dark matter
We present two models where the familiar leptonic symmetry
is a gauge symmetry. We show how anomaly cancellation constrains the allowed
theories, with one of them requiring a fourth sequential chiral standard model
fermion generation and a second one with three generations, requiring gauging
of with representing the baryon number
of the th generation quarks. Unlike global models which
always leads to inverted mass hierarchy for neutrinos, the gauged version can
lead to normal hierarchy. We show how to construct realistic models in both the
cases and discuss the dark matter candidate in both. In our model, the breaking
of is responsible for neutrino mass via type-I
mechanism whereas the real part of breaking scalar
field (called here) plays the role of freeze-in dark matter candidate.
Since is unstable, for it to qualify as dark matter, its lifetime must
be larger than the age of the Universe, implying that the relic of is
generated through freeze-in mechanism and its mass must be less than an MeV. We
also discuss the possibility of explaining both muon and electron while
being consistent with the dark matter relic density and lifetime constraints.Comment: 31 pages, 10 captioned figures, Accepted for publication in Phys.
Lett.
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