1,106 research outputs found
BrainPainter: A software for the visualisation of brain structures, biomarkers and associated pathological processes
We present BrainPainter, a software that automatically generates images of
highlighted brain structures given a list of numbers corresponding to the
output colours of each region. Compared to existing visualisation software
(i.e. Freesurfer, SPM, 3D Slicer), BrainPainter has three key advantages: (1)
it does not require the input data to be in a specialised format, allowing
BrainPainter to be used in combination with any neuroimaging analysis tools,
(2) it can visualise both cortical and subcortical structures and (3) it can be
used to generate movies showing dynamic processes, e.g. propagation of
pathology on the brain. We highlight three use cases where BrainPainter was
used in existing neuroimaging studies: (1) visualisation of the degree of
atrophy through interpolation along a user-defined gradient of colours, (2)
visualisation of the progression of pathology in Alzheimer's disease as well as
(3) visualisation of pathology in subcortical regions in Huntington's disease.
Moreover, through the design of BrainPainter we demonstrate the possibility of
using a powerful 3D computer graphics engine such as Blender to generate brain
visualisations for the neuroscience community. Blender's capabilities, e.g.
particle simulations, motion graphics, UV unwrapping, raster graphics editing,
raytracing and illumination effects, open a wealth of possibilities for brain
visualisation not available in current neuroimaging software. BrainPainter is
customisable, easy to use, and can run straight from the web browser:
https://brainpainter.csail.mit.edu , as well as from source-code packaged in a
docker container: https://github.com/mrazvan22/brain-coloring . It can be used
to visualise biomarker data from any brain imaging modality, or simply to
highlight a particular brain structure for e.g. anatomy courses.Comment: Accepted at the MICCAI Multimodal Brain Imaging Analysis (MBIA)
workshop, 201
Bayesian Image Reconstruction using Deep Generative Models
Machine learning models are commonly trained end-to-end and in a supervised
setting, using paired (input, output) data. Examples include recent
super-resolution methods that train on pairs of (low-resolution,
high-resolution) images. However, these end-to-end approaches require
re-training every time there is a distribution shift in the inputs (e.g., night
images vs daylight) or relevant latent variables (e.g., camera blur or hand
motion). In this work, we leverage state-of-the-art (SOTA) generative models
(here StyleGAN2) for building powerful image priors, which enable application
of Bayes' theorem for many downstream reconstruction tasks. Our method,
Bayesian Reconstruction through Generative Models (BRGM), uses a single
pre-trained generator model to solve different image restoration tasks, i.e.,
super-resolution and in-painting, by combining it with different forward
corruption models. We keep the weights of the generator model fixed, and
reconstruct the image by estimating the Bayesian maximum a-posteriori (MAP)
estimate over the input latent vector that generated the reconstructed image.
We further use variational inference to approximate the posterior distribution
over the latent vectors, from which we sample multiple solutions. We
demonstrate BRGM on three large and diverse datasets: (i) 60,000 images from
the Flick Faces High Quality dataset (ii) 240,000 chest X-rays from MIMIC III
and (iii) a combined collection of 5 brain MRI datasets with 7,329 scans.
Across all three datasets and without any dataset-specific hyperparameter
tuning, our simple approach yields performance competitive with current
task-specific state-of-the-art methods on super-resolution and in-painting,
while being more generalisable and without requiring any training. Our source
code and pre-trained models are available online:
https://razvanmarinescu.github.io/brgm/.Comment: 27 pages, 17 figures, 5 table
Divergent perspectives about social problems in Romania. A longitudinal literature review
This research primarily focuses on identifying the main trends documented in the scientific analysis of the way in which the Romanian media presented the internal social aspect
Modelling the Neuroanatomical Progression of Alzheimer's Disease and Posterior Cortical Atrophy
In order to find effective treatments for Alzheimer's disease (AD), we need
to identify subjects at risk of AD as early as possible. To this end, recently
developed disease progression models can be used to perform early diagnosis, as
well as predict the subjects' disease stages and future evolution. However,
these models have not yet been applied to rare neurodegenerative diseases, are
not suitable to understand the complex dynamics of biomarkers, work only on
large multimodal datasets, and their predictive performance has not been
objectively validated. In this work I developed novel models of disease
progression and applied them to estimate the progression of Alzheimer's disease
and Posterior Cortical atrophy, a rare neurodegenerative syndrome causing
visual deficits. My first contribution is a study on the progression of
Posterior Cortical Atrophy, using models already developed: the Event-based
Model (EBM) and the Differential Equation Model (DEM). My second contribution
is the development of DIVE, a novel spatio-temporal model of disease
progression that estimates fine-grained spatial patterns of pathology,
potentially enabling us to understand complex disease mechanisms relating to
pathology propagation along brain networks. My third contribution is the
development of Disease Knowledge Transfer (DKT), a novel disease progression
model that estimates the multimodal progression of rare neurodegenerative
diseases from limited, unimodal datasets, by transferring information from
larger, multimodal datasets of typical neurodegenerative diseases. My fourth
contribution is the development of novel extensions for the EBM and the DEM,
and the development of novel measures for performance evaluation of such
models. My last contribution is the organization of the TADPOLE challenge, a
competition which aims to identify algorithms and features that best predict
the evolution of AD.Comment: PhD thesis; Defended in Jan 2019 at University College Londo
Production Planning for Integrated Primary and Secondary Lumber Manufacturing
This paper describes two linear programming models that were developed for production planning in value-added lumber manufacturing facilities. One model is designed for nonintegrated value-added facilities; the other is designed for value-added facilities integrated with a sawmill. The models were then used to explore the financial benefits for a sawmill to integrate a value-added lumber manufacturing facility at the back end of the mill. Net revenues are compared from the sawmill's point of view for two experimental cases. In Case 1 the sawmill sells its entire lumber production to the market (including to an independent value-added facility). In Case 2, the sawmill sells only the lumber that it is not directed to the value-added facility for further processing. Net revenue for Case 2 exceeds the net revenue of Case 1 by 10%. Results shown demonstrate that production decisions in the value-added facility had a significant influence on production decisions in the sawmill
A REVIEW OF PHYTOREMEDIATION STRATEGIES FOR SOILS POLLUTED WITH HEAVY METALS
Mining operations, industrial production and domestic and agricultural use of metal and metal containing compound have resulted in the release of toxic metals into the environment. Heavy metal pollution has serious implications for the human health and the environment. Since heavy metals are nonbiodegradable, they accumulate in the environment and subsequently contaminate the food chain. Few heavy metals are toxic and lethal in trace concentrations and can be teratogenic, mutagenic, endocrine disruptors while others can cause behavioral and neurological disorders among infants and children. Therefore, remediation of heavy metals contaminated soil could be the only effective option to reduce the negative effects on ecosystem health. Different physical and chemical methods used for this purpose suffer from serious limitations like high cost, intensive labor, alterationof soil properties and disturbance of soil native microorganisms. Phytoremediationis the use of plants and associated soil microbes to reduce the concentrations or toxic effects of contaminants in the environments. In this article are reviewed the stratagies in the phytoremediation for remediating heavy metals from polluted soils. Phytoextraction and phytostabilization are the most promising and alternative methods for soil reclamation
The first coefficients of the asymptotic expansion of the Bergman kernel of the spin^c Dirac operator
We establish the existence of the asymptotic expansion of the Bergman kernel
associated to the spin-c Dirac operators acting on high tensor powers of line
bundles with non-degenerate mixed curvature (negative and positive eigenvalues)
by extending the paper " On the asymptotic expansion of Bergman kernel "
(math.DG/0404494) of Dai-Liu-Ma. We compute the second coefficient b_1 in the
asymptotic expansion using the method of our paper "Generalized Bergman kernels
on symplectic manifolds" (math.DG/0411559).Comment: 21 pages, to appear in Internat. J. Math. Precisions added in the
abstrac
A note on the calculation of the effective range
The closed form of the first order non-linear differential equation that is
satisfied by the effective range within the variable phase formulation of
scattering theory is discussed. It is shown that the conventional method of
determining the effective range, by fitting a numerical solution of the
Schr\"odinger equation to known asymptotic boundary conditions, can be modified
to include the first order contribution of a long range interaction.Comment: 4 page
Disease Knowledge Transfer across Neurodegenerative Diseases
We introduce Disease Knowledge Transfer (DKT), a novel technique for
transferring biomarker information between related neurodegenerative diseases.
DKT infers robust multimodal biomarker trajectories in rare neurodegenerative
diseases even when only limited, unimodal data is available, by transferring
information from larger multimodal datasets from common neurodegenerative
diseases. DKT is a joint-disease generative model of biomarker progressions,
which exploits biomarker relationships that are shared across diseases. Our
proposed method allows, for the first time, the estimation of plausible,
multimodal biomarker trajectories in Posterior Cortical Atrophy (PCA), a rare
neurodegenerative disease where only unimodal MRI data is available. For this
we train DKT on a combined dataset containing subjects with two distinct
diseases and sizes of data available: 1) a larger, multimodal typical AD (tAD)
dataset from the TADPOLE Challenge, and 2) a smaller unimodal Posterior
Cortical Atrophy (PCA) dataset from the Dementia Research Centre (DRC), for
which only a limited number of Magnetic Resonance Imaging (MRI) scans are
available. Although validation is challenging due to lack of data in PCA, we
validate DKT on synthetic data and two patient datasets (TADPOLE and PCA
cohorts), showing it can estimate the ground truth parameters in the simulation
and predict unseen biomarkers on the two patient datasets. While we
demonstrated DKT on Alzheimer's variants, we note DKT is generalisable to other
forms of related neurodegenerative diseases. Source code for DKT is available
online: https://github.com/mrazvan22/dkt.Comment: accepted at MICCAI 2019, 13 pages, 5 figures, 2 table
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