1,335 research outputs found
Reachability Based Web Page Ranking Using Wavelets
AbstractA naïve approach has been made by applying the concept of reachability for web page ranking and implementing multi resolution analysis using Haar wavelet to order the web pages. In this article, page ranking has been done by developing a structured signal using in links, out links and reachability values of the web pages of network graphs. Using Haar wavelet, the page ranking is proposed and developed. The average and detailed coefficients of the input signal and the down sampling process provides the necessary page ranking of web pages. This approach does not involve any iterative technique, damping factor or initialization of the page ranks. In this paper, comparison between the original page rank, category-based page rank and the proposed approach have been made. The result reflects the role of paths between the pages in page rankings
GP-Unet: Lesion Detection from Weak Labels with a 3D Regression Network
We propose a novel convolutional neural network for lesion detection from
weak labels. Only a single, global label per image - the lesion count - is
needed for training. We train a regression network with a fully convolutional
architecture combined with a global pooling layer to aggregate the 3D output
into a scalar indicating the lesion count. When testing on unseen images, we
first run the network to estimate the number of lesions. Then we remove the
global pooling layer to compute localization maps of the size of the input
image. We evaluate the proposed network on the detection of enlarged
perivascular spaces in the basal ganglia in MRI. Our method achieves a
sensitivity of 62% with on average 1.5 false positives per image. Compared with
four other approaches based on intensity thresholding, saliency and class maps,
our method has a 20% higher sensitivity.Comment: Article published in MICCAI 2017. We corrected a few errors from the
first version: padding, loss, typos and update of the DOI numbe
Distance Metric Learning using Graph Convolutional Networks: Application to Functional Brain Networks
Evaluating similarity between graphs is of major importance in several
computer vision and pattern recognition problems, where graph representations
are often used to model objects or interactions between elements. The choice of
a distance or similarity metric is, however, not trivial and can be highly
dependent on the application at hand. In this work, we propose a novel metric
learning method to evaluate distance between graphs that leverages the power of
convolutional neural networks, while exploiting concepts from spectral graph
theory to allow these operations on irregular graphs. We demonstrate the
potential of our method in the field of connectomics, where neuronal pathways
or functional connections between brain regions are commonly modelled as
graphs. In this problem, the definition of an appropriate graph similarity
function is critical to unveil patterns of disruptions associated with certain
brain disorders. Experimental results on the ABIDE dataset show that our method
can learn a graph similarity metric tailored for a clinical application,
improving the performance of a simple k-nn classifier by 11.9% compared to a
traditional distance metric.Comment: International Conference on Medical Image Computing and
Computer-Assisted Interventions (MICCAI) 201
Extracting the Groupwise Core Structural Connectivity Network: Bridging Statistical and Graph-Theoretical Approaches
Finding the common structural brain connectivity network for a given
population is an open problem, crucial for current neuro-science. Recent
evidence suggests there's a tightly connected network shared between humans.
Obtaining this network will, among many advantages , allow us to focus
cognitive and clinical analyses on common connections, thus increasing their
statistical power. In turn, knowledge about the common network will facilitate
novel analyses to understand the structure-function relationship in the brain.
In this work, we present a new algorithm for computing the core structural
connectivity network of a subject sample combining graph theory and statistics.
Our algorithm works in accordance with novel evidence on brain topology. We
analyze the problem theoretically and prove its complexity. Using 309 subjects,
we show its advantages when used as a feature selection for connectivity
analysis on populations, outperforming the current approaches
Spectral Graph Convolutions for Population-based Disease Prediction
Exploiting the wealth of imaging and non-imaging information for disease
prediction tasks requires models capable of representing, at the same time,
individual features as well as data associations between subjects from
potentially large populations. Graphs provide a natural framework for such
tasks, yet previous graph-based approaches focus on pairwise similarities
without modelling the subjects' individual characteristics and features. On the
other hand, relying solely on subject-specific imaging feature vectors fails to
model the interaction and similarity between subjects, which can reduce
performance. In this paper, we introduce the novel concept of Graph
Convolutional Networks (GCN) for brain analysis in populations, combining
imaging and non-imaging data. We represent populations as a sparse graph where
its vertices are associated with image-based feature vectors and the edges
encode phenotypic information. This structure was used to train a GCN model on
partially labelled graphs, aiming to infer the classes of unlabelled nodes from
the node features and pairwise associations between subjects. We demonstrate
the potential of the method on the challenging ADNI and ABIDE databases, as a
proof of concept of the benefit from integrating contextual information in
classification tasks. This has a clear impact on the quality of the
predictions, leading to 69.5% accuracy for ABIDE (outperforming the current
state of the art of 66.8%) and 77% for ADNI for prediction of MCI conversion,
significantly outperforming standard linear classifiers where only individual
features are considered.Comment: International Conference on Medical Image Computing and
Computer-Assisted Interventions (MICCAI) 201
Linear models of activation cascades: analytical solutions and coarse-graining of delayed signal transduction
Cellular signal transduction usually involves activation cascades, the
sequential activation of a series of proteins following the reception of an
input signal. Here we study the classic model of weakly activated cascades and
obtain analytical solutions for a variety of inputs. We show that in the
special but important case of optimal-gain cascades (i.e., when the
deactivation rates are identical) the downstream output of the cascade can be
represented exactly as a lumped nonlinear module containing an incomplete gamma
function with real parameters that depend on the rates and length of the
cascade, as well as parameters of the input signal. The expressions obtained
can be applied to the non-identical case when the deactivation rates are random
to capture the variability in the cascade outputs. We also show that cascades
can be rearranged so that blocks with similar rates can be lumped and
represented through our nonlinear modules. Our results can be used both to
represent cascades in computational models of differential equations and to fit
data efficiently, by reducing the number of equations and parameters involved.
In particular, the length of the cascade appears as a real-valued parameter and
can thus be fitted in the same manner as Hill coefficients. Finally, we show
how the obtained nonlinear modules can be used instead of delay differential
equations to model delays in signal transduction.Comment: 18 pages, 7 figure
Histological and immunological correlates of suspected leprosy lesions
Thirty-two subjects with suspected leprosy lesions were investigated to assess various
modalities of sensibility and sweatfunction and these were correlated with immunological
and histological parameters.
It was found that pain and temperature, mediated by small unmyelinated fibres were
impaired in the early lesions. Impairment of sweat function was seen only when one of the
modalities of sensibility was also affected Antibodies specific to a protein (35 kDa) antigen
and phenolic glycolipid 1 of Mycobacterium leprae were positive in nine and 12 cases
respectively, while 15 of the 31 biopsies revealed the presence of mycobacterial antigens
in these lesions. The implications of these findings are discussed
NETWORK FLOW WITH FUZZY ARC LENGTHS USING HAAR RANKING
ABSTRACT Shortest path problem is a classical and the most widely studied phenomenon in combinatorial optimization. In a classical shortest path problem, the distance of the arcs between different nodes of a network are assumed to be certain. In some uncertain situations, the distance will be calculated as a fuzzy number depending on the number of parameters considered. This article proposes a new approach based on Haar ranking of fuzzy numbers to find the shortest path between nodes of a given network. The combination of Haar ranking and the well-known Dijkstra's algorithm for finding the shortest path have been used to identify the shortest path between given nodes of a network. The numerical examples ensure the feasibility and validity of the proposed method
Cosmological models with bulk viscosity in presence of adiabatic matter creation and with G, c and Lambda variables
Some properties of cosmological models with a time variable bulk viscous
coefficient in presence of adiabatic mater creation and G, c, Lambda variables
are investigated in the framework of flat FRW line element. We trivially find a
set of solutions through Dimensional Analysis. In all the studied cases it is
found that the behaviour of these constants is inversely prportional to the
cosmic time.Comment: 12 pages. We have been rewriting and completing the bibliography of
this paper. Submitted to General Relativity and Gravitatio
Nonlinear spinor field in Bianchi type-I Universe filled with viscous fluid: numerical solutions
We consider a system of nonlinear spinor and a Bianchi type I gravitational
fields in presence of viscous fluid. The nonlinear term in the spinor field
Lagrangian is chosen to be , with being a self-coupling
constant and being a function of the invariants an constructed from
bilinear spinor forms and . Self-consistent solutions to the spinor and
BI gravitational field equations are obtained in terms of , where
is the volume scale of BI universe. System of equations for and \ve,
where \ve is the energy of the viscous fluid, is deduced. This system is
solved numerically for some special cases.Comment: 15 pages, 4 figure
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