38 research outputs found
Separating Topological Noise from Features Using Persistent Entropy
Topology is the branch of mathematics that studies shapes
and maps among them. From the algebraic definition of topology a new
set of algorithms have been derived. These algorithms are identified
with âcomputational topologyâ or often pointed out as Topological Data
Analysis (TDA) and are used for investigating high-dimensional data in a
quantitative manner. Persistent homology appears as a fundamental tool
in Topological Data Analysis. It studies the evolution of kâdimensional
holes along a sequence of simplicial complexes (i.e. a filtration). The set
of intervals representing birth and death times of kâdimensional holes
along such sequence is called the persistence barcode. kâdimensional
holes with short lifetimes are informally considered to be topological
noise, and those with a long lifetime are considered to be topological
feature associated to the given data (i.e. the filtration). In this paper, we
derive a simple method for separating topological noise from topological
features using a novel measure for comparing persistence barcodes called
persistent entropy.Ministerio de EconomĂa y Competitividad MTM2015-67072-
Towards personalized diagnosis of Glioblastoma in Fluid-attenuated inversion recovery (FLAIR) by topological interpretable machine learning
Glioblastoma multiforme (GBM) is a fast-growing and highly invasive brain
tumour, it tends to occur in adults between the ages of 45 and 70 and it
accounts for 52 percent of all primary brain tumours. Usually, GBMs are
detected by magnetic resonance images (MRI). Among MRI, Fluid-attenuated
inversion recovery (FLAIR) sequence produces high quality digital tumour
representation. Fast detection and segmentation techniques are needed for
overcoming subjective medical doctors (MDs) judgment. In the present
investigation, we intend to demonstrate by means of numerical experiments that
topological features combined with textural features can be enrolled for GBM
analysis and morphological characterization on FLAIR. To this extent, we have
performed three numerical experiments. In the first experiment, Topological
Data Analysis (TDA) of a simplified 2D tumour growth mathematical model had
allowed to understand the bio-chemical conditions that facilitate tumour
growth: the higher the concentration of chemical nutrients the more virulent
the process. In the second experiment topological data analysis was used for
evaluating GBM temporal progression on FLAIR recorded within 90 days following
treatment (e.g., chemo-radiation therapy - CRT) completion and at progression.
The experiment had confirmed that persistent entropy is a viable statistics for
monitoring GBM evolution during the follow-up period. In the third experiment
we had developed a novel methodology based on topological and textural features
and automatic interpretable machine learning for automatic GBM classification
on FLAIR. The algorithm reached a classification accuracy up to the 97%.Comment: 22 pages; 16 figure
Topological classifier for detecting the emergence of epileptic seizures
Objective
An innovative method based on topological data analysis is introduced for classifying EEG recordings of patients affected by epilepsy. We construct a topological space from a collection of EEGs signals using Persistent Homology; then, we analyse the space by Persistent entropy, a global topological feature, in order to classify healthy and epileptic signals.
Results
The performance of the resulting one-feature-based linear topological classifier is tested by analysing the Physionet dataset. The quality of classification is evaluated in terms of the Area Under Curve (AUC) of the receiver operating characteristic curve. It is shown that the linear topological classifier has an AUC equal to 97.2% while the performance of a classifier based on Sample Entropy has an AUC equal to 62.0%
Using Topological Data Analysis for diagnosis pulmonary embolism
Pulmonary Embolism (PE) is a common and potentially lethal condition. Most
patients die within the first few hours from the event. Despite diagnostic
advances, delays and underdiagnosis in PE are common.To increase the diagnostic
performance in PE, current diagnostic work-up of patients with suspected acute
pulmonary embolism usually starts with the assessment of clinical pretest
probability using plasma d-Dimer measurement and clinical prediction rules. The
most validated and widely used clinical decision rules are the Wells and Geneva
Revised scores. We aimed to develop a new clinical prediction rule (CPR) for PE
based on topological data analysis and artificial neural network. Filter or
wrapper methods for features reduction cannot be applied to our dataset: the
application of these algorithms can only be performed on datasets without
missing data. Instead, we applied Topological data analysis (TDA) to overcome
the hurdle of processing datasets with null values missing data. A topological
network was developed using the Iris software (Ayasdi, Inc., Palo Alto). The PE
patient topology identified two ares in the pathological group and hence two
distinct clusters of PE patient populations. Additionally, the topological
netowrk detected several sub-groups among healthy patients that likely are
affected with non-PE diseases. TDA was further utilized to identify key
features which are best associated as diagnostic factors for PE and used this
information to define the input space for a back-propagation artificial neural
network (BP-ANN). It is shown that the area under curve (AUC) of BP-ANN is
greater than the AUCs of the scores (Wells and revised Geneva) used among
physicians. The results demonstrate topological data analysis and the BP-ANN,
when used in combination, can produce better predictive models than Wells or
revised Geneva scores system for the analyzed cohortComment: 18 pages, 5 figures, 6 tables. arXiv admin note: text overlap with
arXiv:cs/0308031 by other authors without attributio
On the Intersection of Explainable and Reliable AI for physical fatigue prediction
In the era of Industry 4.0, the use of Artificial Intelligence (AI) is widespread in occupational settings. Since dealing with human safety, explainability and trustworthiness of AI are even more important than achieving high accuracy. eXplainable AI (XAI) is investigated in this paper to detect physical fatigue during manual material handling task simulation. Besides comparing global rule-based XAI models (LLM and DT) to black-box models (NN, SVM, XGBoost) in terms of performance, we also compare global models with local ones (LIME over XGBoost). Surprisingly, global and local approaches achieve similar conclusions, in terms of feature importance. Moreover, an expansion from local rules to global rules is designed for Anchors, by posing an appropriate optimization method (Anchors coverage is enlarged from an original low value, 11%, up to 43%). As far as trustworthiness is concerned, rule sensitivity analysis drives the identification of optimized regions in the feature space, where physical fatigue is predicted with zero statistical error. The discovery of such ânon-fatigue regionsâ helps certifying the organizational and clinical decision making
Identification of functional sets in mechanical assembly models
Easy retrieval of product data and related information is extremely important for knowledge and data reuse in new product development. Nowadays the adoption of PDM (Product Data Management) systems makes the reuse easy providing means for documenting all the data related to a product, thus making possible their retrieval through the inserted metadata. Unfortunately, large datasets are available in which data are not documented; therefore, retrieval systems based on content similarities according to different criteria would be beneficial. In this paper, we face the problem of identifying functional sets. The main difficulties relay in the variety in terms of shape and representation of the components that can achieve the same functionality. To overcome this issue, we present a multi-step approach, which considers a component embedded in the whole assembly model, improving component characterization
CAD Assembly Retrieval and Browsing
This paper presents a method for the retrieval and inspection of similar CAD assemblies in a database according to a user query. The method exploits the information on componentsâ shape and relationships (e.g. contacts and regular patterns) automatically extracted from the STEP descriptions of CAD assemblies and stored in the so-called Enriched Assembly Model. It evaluates the similarity among assemblies in terms of the componentsâ shapes and joints. A graphical interface highlighting the elements in the assembly similar to the query has been developed to facilitate the inspection of the obtained results