Goto

Collaborating Authors

 Performance Analysis


Evaluation metrics: leave your comfort zone and try MCC and Brier Score

#artificialintelligence

Data science is an interdisciplinary field that uses scientific methods, processes, algorithms and systems to extract knowledge and insights from noisy, structured and unstructured data, and apply knowledge and actionable insights from data across a broad range of application domains. Machine learning instead is the study of computer algorithms that can improve automatically through experience and by the use of data. It is seen as a part of artificial intelligence. Data scientist around the world apply machine learning in order to build models able to predict future events, cluster people/objects into similar groups and also identify unexpected anomalies. Every enthusiastic data scientist knows that the most exciting part of machine learning is to choose the coolest algorithm capable of solve the problem of interest (Supervised or Unsupervised).


Implementing Naive Bayes From Scratch

#artificialintelligence

As stated in the general overview, we need to calculate the summary statistics for each class (and feature) as well as the prior. First of all, we need to gather some basic information about the dataset and create three zero-matrices to store the mean, the variance, and the prior for each class. Next, we iterate over all the classes, compute the statistics and update our zero-matrices accordingly. For example, assume we have two unique classes (0,1) and two features in our dataset. The matrix storing the mean values, therefore will have a two rows and two columns (2x2). The prior is just a single vector (1x2), containing the ratio of a single classes' samples divided by the total sample size.


Knowledge Tracing: A Survey

arXiv.org Artificial Intelligence

Humans ability to transfer knowledge through teaching is one of the essential aspects for human intelligence. A human teacher can track the knowledge of students to customize the teaching on students needs. With the rise of online education platforms, there is a similar need for machines to track the knowledge of students and tailor their learning experience. This is known as the Knowledge Tracing (KT) problem in the literature. Effectively solving the KT problem would unlock the potential of computer-aided education applications such as intelligent tutoring systems, curriculum learning, and learning materials' recommendation. Moreover, from a more general viewpoint, a student may represent any kind of intelligent agents including both human and artificial agents. Thus, the potential of KT can be extended to any machine teaching application scenarios which seek for customizing the learning experience for a student agent (i.e., a machine learning model). In this paper, we provide a comprehensive and systematic review for the KT literature. We cover a broad range of methods starting from the early attempts to the recent state-of-the-art methods using deep learning, while highlighting the theoretical aspects of models and the characteristics of benchmark datasets. Besides these, we shed light on key modelling differences between closely related methods and summarize them in an easy-to-understand format. Finally, we discuss current research gaps in the KT literature and possible future research and application directions.


LoMar: A Local Defense Against Poisoning Attack on Federated Learning

arXiv.org Artificial Intelligence

Federated learning (FL) provides a high efficient decentralized machine learning framework, where the training data remains distributed at remote clients in a network. Though FL enables a privacy-preserving mobile edge computing framework using IoT devices, recent studies have shown that this approach is susceptible to poisoning attacks from the side of remote clients. To address the poisoning attacks on FL, we provide a \textit{two-phase} defense algorithm called {Lo}cal {Ma}licious Facto{r} (LoMar). In phase I, LoMar scores model updates from each remote client by measuring the relative distribution over their neighbors using a kernel density estimation method. In phase II, an optimal threshold is approximated to distinguish malicious and clean updates from a statistical perspective. Comprehensive experiments on four real-world datasets have been conducted, and the experimental results show that our defense strategy can effectively protect the FL system. {Specifically, the defense performance on Amazon dataset under a label-flipping attack indicates that, compared with FG+Krum, LoMar increases the target label testing accuracy from $96.0\%$ to $98.8\%$, and the overall averaged testing accuracy from $90.1\%$ to $97.0\%$.


Fake Hilsa Fish Detection Using Machine Vision

arXiv.org Artificial Intelligence

Hilsa is the national fish of Bangladesh. Bangladesh is earning a lot of foreign currency by exporting this fish. Unfortunately, in recent days, some unscrupulous businessmen are selling fake Hilsa fishes to gain profit. The Sardines and Sardinella are the most sold in the market as Hilsa. The government agency of Bangladesh, namely Bangladesh Food Safety Authority said that these fake Hilsa fish contain high levels of cadmium and lead which are detrimental for humans. In this research, we have proposed a method that can readily identify original Hilsa fish and fake Hilsa fish. Based on the research available on online literature, we are the first to do research on identifying original Hilsa fish. We have collected more than 16,000 images of original and counterfeit Hilsa fish. To classify these images, we have used several deep learning-based models. Then, the performance has been compared between them. Among those models, DenseNet201 achieved the highest accuracy of 97.02%.


AnomMAN: Detect Anomaly on Multi-view Attributed Networks

arXiv.org Artificial Intelligence

Anomaly detection on attributed networks is widely used in web shopping, financial transactions, communication networks, and so on. However, most work tries to detect anomalies on attributed networks only considering a single interaction action, which cannot consider rich kinds of interaction actions in multi-view attributed networks. In fact, it remains a challenging task to consider all different kinds of interaction actions uniformly and detect anomalous instances in multi-view attributed networks. In this paper, we propose a Graph Convolution based framework, AnomMAN, to detect \textbf{Anom}aly on \textbf{M}ulti-view \textbf{A}ttributed \textbf{N}etworks. To consider the attributes and all interaction actions jointly, we use the attention mechanism to define the importance of all views in networks. Besides, the Graph Convolution operation cannot be simply applied in anomaly detection tasks on account of its low-pass characteristic. Therefore, AnomMAN uses a graph auto-encoder module to overcome the shortcoming and transform it to our strength. According to experiments on real-world datasets, AnomMAN outperforms state-of-the-art models and two variants of our proposed model. Besides, the Accuracy@50 indicator of AnomMAN reaches 1.000 on the dataset, which shows that the top 50 anomalous instances detected by AnomMAN are all anomalous ones.


Experts warn prenatal screening tests can lead to false positive results in some cases

FOX News

Fox News Flash top headlines are here. Check out what's clicking on Foxnews.com. Non-invasive prenatal testing (NIPT) on pregnant women to detect the risk of a fetus having rare genetic abnormalities may often be wrong, according to recent reports. These tests, according to multiple health experts, can actually give false positives, which can create significant angst in expecting parents. Health experts explained to Fox News that NIPT works by taking blood samples from the pregnant mother and then analyzing fragments of free-floating cell-free DNA (cfDNA).


Applications of Signature Methods to Market Anomaly Detection

arXiv.org Machine Learning

While these instances are called outliers (anomalies), the normal instances are called inliers. Anomaly detection is a fundamental research problem that has been investigated by researchers from diverse research fields and application areas. Anomaly detection can be made manually by searching through whole data clouds to diagnose the problem, but clearly this is a long and labourintensive process. Anomaly detection often appears in the context of uncertainty, i.e. absence, principal or not, of knowledge on the data generating process. Hence, over time, a plethora of anomaly detection techniques ranging from simple statistical techniques to complex machine learning algorithms has been developed for certain application areas such as fraud detection in financial transactions (West and Bhattacharya (2016)), fault detection in production (Miljković (2011)), intrusion detection in a computer network (Sabahi and Movaghar (2008)), etc. Some of the well known statistical methods such as z-score, Tukey method (Interquartile Range) or Gaussian Mixture models can be useful for the initial screening of outliers. Although these statistical or econometric anomaly detection methods have been well rooted in the literature (we refer the reader to Chandola et al. (2009) for an extensive review) dating back to Edgeworth (1887), many of them have failed to provide sufficient performance and accuracy in the last decade. This is mainly in view of big data collected from various sources such as financial transactions, health records, and surveillance logs etc. Nowadays high-volume, high-velocity, and high-variety data sets demand cost-effective novel data analytics for decision-making and to infer useful insights


United adversarial learning for liver tumor segmentation and detection of multi-modality non-contrast MRI

arXiv.org Artificial Intelligence

Simultaneous segmentation and detection of liver tumors (hemangioma and hepatocellular carcinoma (HCC)) by using multi-modality non-contrast magnetic resonance imaging (NCMRI) are crucial for the clinical diagnosis. However, it is still a challenging task due to: (1) the HCC information on NCMRI is invisible or insufficient makes extraction of liver tumors feature difficult; (2) diverse imaging characteristics in multi-modality NCMRI causes feature fusion and selection difficult; (3) no specific information between hemangioma and HCC on NCMRI cause liver tumors detection difficult. In this study, we propose a united adversarial learning framework (UAL) for simultaneous liver tumors segmentation and detection using multi-modality NCMRI. The UAL first utilizes a multi-view aware encoder to extract multi-modality NCMRI information for liver tumor segmentation and detection. In this encoder, a novel edge dissimilarity feature pyramid module is designed to facilitate the complementary multi-modality feature extraction. Second, the newly designed fusion and selection channel is used to fuse the multi-modality feature and make the decision of the feature selection. Then, the proposed mechanism of coordinate sharing with padding integrates the multi-task of segmentation and detection so that it enables multi-task to perform united adversarial learning in one discriminator. Lastly, an innovative multi-phase radiomics guided discriminator exploits the clear and specific tumor information to improve the multi-task performance via the adversarial learning strategy. The UAL is validated in corresponding multi-modality NCMRI (i.e. T1FS pre-contrast MRI, T2FS MRI, and DWI) and three phases contrast-enhanced MRI of 255 clinical subjects. The experiments show that UAL has great potential in the clinical diagnosis of liver tumors.


Detection of extragalactic Ultra-Compact Dwarfs and Globular Clusters using Explainable AI techniques

arXiv.org Artificial Intelligence

Compact stellar systems such as Ultra-compact dwarfs (UCDs) and Globular Clusters (GCs) around galaxies are known to be the tracers of the merger events that have been forming these galaxies. Therefore, identifying such systems allows to study galaxies mass assembly, formation and evolution. However, in the lack of spectroscopic information detecting UCDs/GCs using imaging data is very uncertain. Here, we aim to train a machine learning model to separate these objects from the foreground stars and background galaxies using the multi-wavelength imaging data of the Fornax galaxy cluster in 6 filters, namely u, g, r, i, J and Ks. The classes of objects are highly imbalanced which is problematic for many automatic classification techniques. Hence, we employ Synthetic Minority Over-sampling to handle the imbalance of the training data. Then, we compare two classifiers, namely Localized Generalized Matrix Learning Vector Quantization (LGMLVQ) and Random Forest (RF). Both methods are able to identify UCDs/GCs with a precision and a recall of >93 percent and provide relevances that reflect the importance of each feature dimension %(colors and angular sizes) for the classification. Both methods detect angular sizes as important markers for this classification problem. While it is astronomical expectation that color indices of u-i and i-Ks are the most important colors, our analysis shows that colors such as g-r are more informative, potentially because of higher signal-to-noise ratio. Besides the excellent performance the LGMLVQ method allows further interpretability by providing the feature importance for each individual class, class-wise representative samples and the possibility for non-linear visualization of the data as demonstrated in this contribution. We conclude that employing machine learning techniques to identify UCDs/GCs can lead to promising results.