Due to the various appearance of the polyps and the tiny contrast between the polyp area and its surrounding background, accurate polyp segmentation has become a challenging task. To tackle this issue, we introduce a boundary-enhanced framework for polyp segmentation, called the Focused on Boundary Segmentation (FoBS) framework, that leverages multi-level collaboration among sample, feature, and optimization. It places greater emphasis on the polyp boundary to improve the accuracy of segmentation. Firstly, a boundary-aware mixup method is designed to improve the model’s awareness of the boundary. More importantly, we propose deformable laplacian-based feature refining to explicitly strengthen the representation ability of the boundary features. It employs a deformable Laplacian refinement function to capture discriminative information from a deformable perceptual field, thereby improving its ability to adapt to boundary variations. In addition, we introduce the self-adjusting refinement coefficient learning that enables adaptive control over the refinement strength at each location. Furthermore, we develop a location-sensitive compensation criterion that assigns more importance to the degraded feature after feature refinement during optimization. Extensive quantitative and qualitative experiments on four polyp benchmarks demonstrate the effectiveness of our method for automatic polyp segmentation. Our code is available at https://github.com/TFboys-lzz/ FoBS.

The innovation and evolution of file and storage systems have been influenced by workload analysis. Though cloud storage systems have been widely deployed and used, real-world and large-scale cloud storage workload studies are rare. Previous large-scale distributed storage systems can meet versatility, stability, and reliability requirements. Furthermore, modern cloud storage systems need to meet additional challenges, such as coping with surges in peak loads and rapid expansion of requests. These changes may lead to different characteristics.In this work, we propose DiTing data tracing system and collect workloads with over 242,000 billion requests from the Alibaba cloud. By comparing the normal days and the Single’s Day (the world’s largest online shopping festival), we analyze characteristics such as I/O scale, latency, locality, and load distribution. Our analysis reveals four key observations as follows. First, the virtual layer is the performance bottleneck of modern cloud storage systems during extreme peak periods. Second, the write operations dominate the data access because the application and operating system buffers absorb reads better than writes. Third, the workload is heavily skewed toward a small percentage of virtual cloud disks, with 20% of cloud disks accounting for 80% of I/O requests. Finally, data access shows poor temporal and spatial locality, and the I/O requests are mostly small-scaled. Based on these observations, we propose several suggestions for cloud storage systems, including separating I/O processing from the virtual layer to the proxy layer, deploying heavy and light workload applications on the same node, and adopting a write-friendly cloud disk design for write-skewed requests, etc. In summary, these workload characteristics and suggestions are useful for designing and implementing next-generation cloud storage systems.

Deep generative model, especially variational auto-encoder (VAE), has been successfully employed by more and more recommendation systems. The reason is that it combines the flexibility of probabilistic generative model with the powerful non-linear feature representation ability of deep neural networks. The existing VAE-based recommendation models are usually proposed under global assumption by incorporating simple priors, e.g., a single Gaussian, to regularize the latent variables. This strategy, however, is ineffective when the user is simultaneously interested in different kinds of items, i.e., the user’s preference may be highly diverse. In this paper, thus, we propose a Deep Global and Local Generative Model for recommendation to consider both local and global structure among users (DGLGM) under the Wasserstein auto-encoder framework. Besides keeping the global structure like the existing model, DGLGM adopts a non-parametric Mixture Gaussian distribution with several components to capture the diversity of the users’ preferences. Each component is corresponding to one local structure and its optimal size can be determined via the automatic relevance determination technique. These two parts can be seamlessly integrated and enhance each other. The proposed DGLGM can be efficiently inferred by minimizing its penalized upper bound with the aid of local variational optimization technique. Meanwhile, we theoretically analyze its generalization error bounds to guarantee its performance in sparse feedback data with diversity. By comparing with the state-of-the-art methods, the experimental results demonstrate that DGLGM consistently benefits the recommendation system in top-N recommendation task.

Disk and memory faults are the leading causes of server breakdown. A proactive solution is to predict such hardware failure at the runtime and then isolate the hardware at risk and backup the data. However, the current model-based predictors are incapable of using the discrete time-series data, such as the values of device attributes, which conveys high-level information of the device behavior. In this paper, we propose a novel deep-learning based prediction scheme for system-level hardware failure prediction. We normalize the distribution of samples' attributes from different vendors to make use of diverse training sets. We propose a temporal Convolution Neural Network based model that is insensitive to the noise in the time dimension. Finally, we design a loss function to train the model with extremely imbalanced samples effectively. Experimental results from an open S.M.A.R.T data set and an industrial data set show the effectiveness of the proposed scheme.

We investigate multi-sensor modeling of teachers’ instructional segments (e.g., lecture, group work) from audio recordings collected in 56 classes from eight teachers across five middle schools. Our approach fuses two sensors: a unidirectional microphone for teacher audio and a pressure zone microphone for general classroom audio. We segment and analyze the audio streams with respect to discourse timing, linguistic, and paralinguistic features. We train supervised classifiers to identify the five instructional segments that collectively comprised a majority of the data, achieving teacher-independent F1 scores ranging from 0.49 to 0.60. With respect to individual segments, the individual sensor models and the fused model were on par for Question & Answer and Procedures & Directions segments. For Supervised Seatwork, Small Group Work, and Lecture segments, the classroom model outperformed both the teacher and fusion models. Across all segments, a multi-sensor approach led to an average 8% improvement over the state of the art approach that only analyzed teacher audio. We discuss implications of our findings for the emerging field of multimodal learning analytics.

Nathaniel Blanchard, Patrick Donnelly, Andrew M. Olney, Borhan Samei, Brooke Ward, Xiaoyi Sun, Sean Kelly, Martin Nystrand, Sidney K. D’Mello. Proceedings of the 17th Annual Meeting of the Special Interest Group on Discourse and Dialogue. 2016.

We investigate automatic analysis of teachers' instructional strategies from audio recordings collected in live classrooms. We collected a data set of teacher audio and human-coded instructional activities (e.g., lecture, question and answer, group work) in 76 middle school literature, language arts, and civics classes from eleven teachers across six schools. We automatically segment teacher audio to analyze speech vs. rest patterns, generate automatic transcripts of the teachers' speech to extract natural language features, and compute low-level acoustic features. We train supervised machine learning models to identify occurrences of five key instructional segments (Question & Answer, Procedures and Directions, Supervised Seatwork, Small Group Work, and Lecture) that collectively comprise 76% of the data. Models are validated independently of teacher in order to increase generalizability to new teachers from the same sample. We were able to identify the five instructional segments above chance levels with F1 scores ranging from 0.64 to 0.78. We discuss key findings in the context of teacher modeling for formative assessment and professional development.

We focus on data collection designs for the automated analysis of teacher-student interactions in live classrooms with the goal of identifying instructional activities (e.g., lecturing, discussion) and assessing the quality of dialogic instruction (e.g., analysis of questions). Our designs were motivated by multiple technical requirements and constraints. Most importantly, teachers could be individually micfied but their audio needed to be of excellent quality for automatic speech recognition (ASR) and spoken utterance segmentation. Individual students could not be micfied but classroom audio quality only needed to be sufficient to detect student spoken utterances. Visual information could only be recorded if students could not be identified. Design 1 used an omnidirectional laptop microphone to record both teacher and classroom audio and was quickly deemed unsuitable. In Designs 2 and 3, teachers wore a wireless Samson AirLine 77 vocal headset system, which is a unidirectional microphone with a cardioid pickup pattern. In Design 2, classroom audio was recorded with dual first- generation Microsoft Kinects placed at the front corners of the class. Design 3 used a Crown PZM-30D pressure zone microphone mounted on the blackboard to record classroom audio. Designs 2 and 3 were tested by recording audio in 38 live middle school classrooms from six U.S. schools while trained human coders simultaneously performed live coding of classroom discourse. Qualitative and quantitative analyses revealed that Design 3 was suitable for three of our core tasks: (1) ASR on teacher speech (word recognition rate of 66% and word overlap rate of 69% using Google Speech ASR engine); (2) teacher utterance segmentation (F-measure of 97%); and (3) student utterance segmentation (F-measure of 66%). Ideas to incorporate video and skeletal tracking with dual second-generation Kinects to produce Design 4 are discussed.