TrISec: Training Data-Unaware Imperceptible Security Attacks on Deep Neural Networks

Most of the data manipulation attacks on deep neural networks (DNNs) during the training stage introduce a perceptible noise that can be catered by preprocessing during inference or can be identified during the validation phase. Therefore, data poisoning attacks during inference (e.g., adversarial attacks) are becoming more popular. However, many of them do not consider the imperceptibility factor in their optimization algorithms, and can be detected by correlation and structural similarity analysis, or noticeable (e.g., by humans) in a multi-level security system. Moreover, the majority of the inference attack relies on some knowledge about the training dataset. In this paper, we propose a novel methodology which automatically generates imperceptible attack images by using the back-propagation algorithm on pre-trained DNNs, without requiring any information about the training dataset (i.e., completely training data-unaware). We present a case study on traffic sign detection using the VGGNet trained on the German Traffic Sign Recognition Benchmarks dataset in an autonomous driving use case. Our results demonstrate that the generated attack images successfully perform misclassification while remaining imperceptible in both "subjective" and "objective" quality tests

QuSecNets: Quantization-based Defense Mechanism for Securing Deep Neural Network against Adversarial Attacks

Adversarial examples have emerged as a significant threat to machine learning algorithms, especially to the convolutional neural networks (CNNs). In this paper, we propose two quantization-based defense mechanisms, Constant Quantization (CQ) and Trainable Quantization (TQ), to increase the robustness of CNNs against adversarial examples. CQ quantizes input pixel intensities based on a "fixed" number of quantization levels, while in TQ, the quantization levels are "iteratively learned during the training phase", thereby providing a stronger defense mechanism. We apply the proposed techniques on undefended CNNs against different state-of-the-art adversarial attacks from the open-source \textit{Cleverhans} library. The experimental results demonstrate 50%-96% and 10%-50% increase in the classification accuracy of the perturbed images generated from the MNIST and the CIFAR-10 datasets, respectively, on commonly used CNN (Conv2D(64, 8x8) - Conv2D(128, 6x6) - Conv2D(128, 5x5) - Dense(10) - Softmax()) available in \textit{Cleverhans} library

Analysis of Unsteady Squeezing Flow Between Two Porous Plates With Variable Magnetic Field

Analysis will be made for the non-isothermal Newtonian fuid flow between two unsteady squeezing porous plates under the infuence of variable magnetic feld. The similarity transformations will be used to transform the partial differential equations into nonlinear coupled ordinary differential equations. The modeled nonlinear differential equations representing the flow behavior in the geometry under consideration will be investigated using analytical and numerical method. Comparison of the solutions will be made. Convergence of solution will also be discussed. Flow behavior under the infuence of non-dimensional parameters will be discussed with the help of graphical aids

Morbidity pattern of sick hospitalized preterm infants in Karachi, Pakistan

Despite recent advances, prematurity is associated with high morbidity and mortality in developing countries. We conducted a descriptive case series to identify frequency of various morbidities in premature neonates at Aga Khan University Hospital (AKUH), Karachi, from November 2008 to April 2009. All inborn premature \u3c or = 37 weeks gestation were included in study. The frequency of preterm birth during study period was 13.3% (251/1885) of which 58% (n = 145) required admission in Neonatal Intensive Care Unit (NICU). Mean gestational age was 33 +/- 2.4 weeks and mean birth weight, was 1.88 +/- 0.5 kg. 25% of patients were small for gestational age (SGA) while 75% appropriate for gestational age (AGA). Metabolic derangement was the most common morbidity, observed in 93% of patients followed by sepsis, seen in 43.6% neonates. Respiratory distress syndrome was observed in 35.5% of neonates while intraventricular haemorrhage was seen only in 3.5% patients. Mean length of stay for preterm infants in NICU was 11.5 +/- 9.6 days, 14% (n = 20) preterm neonates expired during NICU stay

Gaussian mixture model based probabilistic modeling of images for medical image segmentation

In this paper, we propose a novel image segmentation algorithm that is based on the probability distributions of the object and background. It uses the variational level sets formulation with a novel region based term in addition to the edge-based term giving a complementary functional, that can potentially result in a robust segmentation of the images. The main theme of the method is that in most of the medical imaging scenarios, the objects are characterized by some typical characteristics such a color, texture, etc. Consequently, an image can be modeled as a Gaussian mixture of distributions corresponding to the object and background. During the procedure of curve evolution, a novel term is incorporated in the segmentation framework which is based on the maximization of the distance between the GMM corresponding to the object and background. The maximization of this distance using differential calculus potentially leads to the desired segmentation results. The proposed method has been used for segmenting images from three distinct imaging modalities i.e. magnetic resonance imaging (MRI), dermoscopy and chromoendoscopy. Experiments show the effectiveness of the proposed method giving better qualitative and quantitative results when compared with the current state-of-the-art. INDEX TERMS Gaussian Mixture Model, Level Sets, Active Contours, Biomedical Engineerin

Salmonella Cholecystitis: Atypical Presentation of a Typical Condition

Salmonella cholecystitis is a rare but important complication of Salmonella typhi infection. We are reporting an 11 years old female child who presented with complaints of high-grade fever, jaundice and right sided abdominal pain (Charcot\u27s triad). Her examination showed tender hepatomegaly. Initial blood results revealed high white cell counts with left shift, deranged liver function tests. Abdominal ultrasonography revealed distended gallbladder with minimal layer of sludge seen within its lumen along with streak of pericholecystic fluid. Blood culture grew Salmonella typhi. She was successfully treated with intravenous ceftriaxone