3,121 research outputs found
Deep Multi-Modal Classification of Intraductal Papillary Mucinous Neoplasms (IPMN) with Canonical Correlation Analysis
Pancreatic cancer has the poorest prognosis among all cancer types.
Intraductal Papillary Mucinous Neoplasms (IPMNs) are radiographically
identifiable precursors to pancreatic cancer; hence, early detection and
precise risk assessment of IPMN are vital. In this work, we propose a
Convolutional Neural Network (CNN) based computer aided diagnosis (CAD) system
to perform IPMN diagnosis and risk assessment by utilizing multi-modal MRI. In
our proposed approach, we use minimum and maximum intensity projections to ease
the annotation variations among different slices and type of MRIs. Then, we
present a CNN to obtain deep feature representation corresponding to each MRI
modality (T1-weighted and T2-weighted). At the final step, we employ canonical
correlation analysis (CCA) to perform a fusion operation at the feature level,
leading to discriminative canonical correlation features. Extracted features
are used for classification. Our results indicate significant improvements over
other potential approaches to solve this important problem. The proposed
approach doesn't require explicit sample balancing in cases of imbalance
between positive and negative examples. To the best of our knowledge, our study
is the first to automatically diagnose IPMN using multi-modal MRI.Comment: Accepted for publication in IEEE International Symposium on
Biomedical Imaging (ISBI) 201
Dual Monte Carlo and Cluster Algorithms
We discuss the development of cluster algorithms from the viewpoint of
probability theory and not from the usual viewpoint of a particular model. By
using the perspective of probability theory, we detail the nature of a cluster
algorithm, make explicit the assumptions embodied in all clusters of which we
are aware, and define the construction of free cluster algorithms. We also
illustrate these procedures by rederiving the Swendsen-Wang algorithm,
presenting the details of the loop algorithm for a worldline simulation of a
quantum 1/2 model, and proposing a free cluster version of the
Swendsen-Wang replica method for the random Ising model. How the principle of
maximum entropy might be used to aid the construction of cluster algorithms is
also discussed.Comment: 25 pages, 4 figures, to appear in Phys.Rev.
Multicanonical Multigrid Monte Carlo
To further improve the performance of Monte Carlo simulations of first-order
phase transitions we propose to combine the multicanonical approach with
multigrid techniques. We report tests of this proposition for the
-dimensional field theory in two different situations. First, we
study quantum tunneling for in the continuum limit, and second, we
investigate first-order phase transitions for in the infinite volume
limit. Compared with standard multicanonical simulations we obtain improvement
factors of several resp. of about one order of magnitude.Comment: 12 pages LaTex, 1 PS figure appended. FU-Berlin preprint FUB-HEP 9/9
Transition matrix Monte Carlo method for quantum systems
We propose an efficient method for Monte Carlo simulation of quantum lattice
models. Unlike most other quantum Monte Carlo methods, a single run of the
proposed method yields the free energy and the entropy with high precision for
the whole range of temperature. The method is based on several recent findings
in Monte Carlo techniques, such as the loop algorithm and the transition matrix
Monte Carlo method. In particular, we derive an exact relation between the DOS
and the expectation value of the transition probability for quantum systems,
which turns out to be useful in reducing the statistical errors in various
estimates.Comment: 6 pages, 4 figure
Profile scaling in decay of nanostructures
The flattening of a crystal cone below its roughening transition is studied
by means of a step flow model. Numerical and analytical analyses show that the
height profile, h(r,t), obeys the scaling scenario dh/dr = F(r t^{-1/4}). The
scaling function is flat at radii r<R(t) \sim t^{1/4}. We find a one parameter
family of solutions for the scaling function, and propose a selection criterion
for the unique solution the system reaches.Comment: 4 pages, RevTex, 3 eps figure
Impurity-induced diffusion bias in epitaxial growth
We introduce two models for the action of impurities in epitaxial growth. In
the first, the interaction between the diffusing adatoms and the impurities is
``barrier''-like and, in the second, it is ``trap''-like. For the barrier
model, we find a symmetry breaking effect that leads to an overall down-hill
current. As expected, such a current produces Edwards-Wilkinson scaling. For
the trap model, no symmetry breaking occurs and the scaling behavior appears to
be of the conserved-KPZ type.Comment: 5 pages(with the 5 figures), latex, revtex3.0, epsf, rotate, multico
A micro-geoarchaeological view on stratigraphy and site formation processes in the Middle, Upper and Epi-Paleolithic layers of Sefunim Cave, Mt. Carmel, Israel
This paper presents a micro-geoarchaeological study carried out on the sedimentary sequence exposed at the entrance of Sefunim Cave, Israel, a sequence that spans from the Middle Paleolithic to the early Epipaleolithic periods. Using FTIR and micromorphological techniques, we investigated the stratigraphic sequence to reconstruct patterns of site use and archaeological formation processes. We identified formation processes that are common among Paleolithic caves sites in the Southern Levant, mainly the deposition of local terra rossa through colluvial sedimentation. Taphonomic disturbances of the deposits range from minimal to moderate, exhibited mainly by root and burrowing activity, but with no evidence for significant transport of archaeological materials. While the upper layers (II–III) are decalcified, the precipitation of secondary calcite results in increasing cementation of the sediments with depth in the lower layers (V–VII). We observed variation at the microscopic scale and identified an inverse correlation between human and carnivore activity throughout the layers. We observed human activity by the presence of micro-archaeological materials such as chert, bone, charcoal, rubified clay, burnt bone and shell, and wood ash. We observed carnivore activity by the presence of phosphatic grains and coprolite fragments as well as chewed and digested bones. We conclude that human activity at the site was characterized by episodes of varying intensity, based on the frequency of archaeological finds within the different layers. The alternating episodes of human and carnivore activity at Sefunim Cave may demonstrate the close-knit interactions and reciprocal relations that humans and carnivore shared at Paleolithic caves.publishedVersio
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