Folded Polynomial Codes for Coded Distributed AA⊤AA^\top-Type Matrix Multiplication

In this paper, due to the important value in practical applications, we consider the coded distributed matrix multiplication problem of computing $AA^\top$ in a distributed computing system with $N$ worker nodes and a master node, where the input matrices $A$ and $A^\top$ are partitioned into $p$-by-$m$ and $m$-by-$p$ blocks of equal-size sub-matrices respectively. For effective straggler mitigation, we propose a novel computation strategy, named \emph{folded polynomial code}, which is obtained by modifying the entangled polynomial codes. Moreover, we characterize a lower bound on the optimal recovery threshold among all linear computation strategies when the underlying field is real number field, and our folded polynomial codes can achieve this bound in the case of $m=1$. Compared with all known computation strategies for coded distributed matrix multiplication, our folded polynomial codes outperform them in terms of recovery threshold, download cost and decoding complexity.Comment: 14 pages, 2 tabl

CLIP Brings Better Features to Visual Aesthetics Learners

The success of pre-training approaches on a variety of downstream tasks has revitalized the field of computer vision. Image aesthetics assessment (IAA) is one of the ideal application scenarios for such methods due to subjective and expensive labeling procedure. In this work, an unified and flexible two-phase \textbf{C}LIP-based \textbf{S}emi-supervised \textbf{K}nowledge \textbf{D}istillation paradigm is proposed, namely \textbf{\textit{CSKD}}. Specifically, we first integrate and leverage a multi-source unlabeled dataset to align rich features between a given visual encoder and an off-the-shelf CLIP image encoder via feature alignment loss. Notably, the given visual encoder is not limited by size or structure and, once well-trained, it can seamlessly serve as a better visual aesthetic learner for both student and teacher. In the second phase, the unlabeled data is also utilized in semi-supervised IAA learning to further boost student model performance when applied in latency-sensitive production scenarios. By analyzing the attention distance and entropy before and after feature alignment, we notice an alleviation of feature collapse issue, which in turn showcase the necessity of feature alignment instead of training directly based on CLIP image encoder. Extensive experiments indicate the superiority of CSKD, which achieves state-of-the-art performance on multiple widely used IAA benchmarks

Dynamic Evolution Analysis of Social Network in cMOOC Based on RSiena Model

The network is a key concept which has been highly valued in connectivism. Research about the static characteristics of social networks in connectivist learning has been carried out in recent years, however, little knowledge exists regarding the principles of network evolution from a dynamic perspective. This article chose the first connectivist massive open and online course (cMOOC) in China, “Internet plus Education: Dialogue between Theory and Practice” as the research object, using the dynamic analysis method of social networks which is based on stochastic actor-oriented models, to reveal the influence of the individual attributes and network structural attributes on the dynamic evolution of social networks in a cMOOC. We found that: 1) the learners with the same sex, the same social identity, and the same type of behaviour tendency found it much easier to interact with each other; 2) there is a heterogeneous phenomenon with course identity, meaning that compared to communicating with other learners, learners are more inclined to reply to a facilitator; and 3) the reciprocity and transitivity have significant effects on social network evolution. This study is valuable for understanding the network evolution and has implications for the improvement of cMOOC design, in turn improving the online learning experience for cMOOC learners

Theoretical Development of Connectivism through Innovative Application in China

As a learning theory that reveals a new learning in the Internet environment, connectivism has become a popular academic topic at the forefront of online learning. The MOOC Research Team at the Distance Education Research Centre at Beijing Normal University designed and developed the first massive open online course, adapting a connectivist (cMOOC) approach in China. Using the data collected from six offerings of the cMOOC over 3 years, the big data paradigm was used for data analysis including complex network analysis, content analysis, text mining, behaviour sequence analysis, epistemic network analysis, and statistical and econometric models. This paper summarizes the findings of the patterns of connectivist learning, including a) the basic characteristics and evolutional patterns of complex networks, b) the characteristics and modes of knowledge production, c) the patterns of instructional interactions, and d) the relationships between pipe and content and between facilitators and learners. It is expected that the outcome of this study could make contributions to understanding the changes of online learning in depth and further promote the theoretical development and practical application of a connectivist approach

Living near the edge: how extreme outcomes and their neighbours drive risky choice

Extreme stimuli are often more salient in perception and memory than moderate stimuli. In risky choice, when people learn the odds and outcomes from experience, the extreme outcomes (best and worst) also stand out. This additional salience leads to more risk-seeking for relative gains than for relative losses—the opposite of what people do when queried in terms of explicit probabilities. Previous research has suggested that this pattern arises because the most extreme experienced outcomes are more prominent in memory. An important open question, however, is what makes these extreme outcomes more prominent? Here we assess whether extreme outcomes stand out because they fall at the edges of the experienced outcome distributions or because they are distinct from other outcomes. Across four experiments, proximity to the edge determined what was treated as extreme: Outcomes at or near the edge of the outcome distribution were both better remembered and more heavily weighted in choice. This prominence did not depend on two metrics of distinctiveness: lower frequency or distance from other outcomes. This finding adds to evidence from other domains that the values at the edges of a distribution have a special role

Satellite-detected ammonia changes in the United States: Natural or anthropogenic impacts

Ammonia (NH3) is the most abundant alkaline component and can react with atmospheric acidic species to form aerosols that can lead to numerous environmental and health issues. Increasing atmospheric NH3 over agricultural regions in the US has been documented. However, spatiotemporal changes of NH3 concentrations over the entire US are still not thoroughly understood, and the factors that drive these changes remain unknown. Herein, we applied the Atmospheric Infrared Sounder (AIRS) monthly NH3 dataset to explore spatiotemporal changes in atmospheric NH3 and the empirical relationships with synthetic N fertilizer application, livestock manure production, and climate factors across the entire US at both regional and pixel levels from 2002 to 2016. We found that, in addition to the US Midwest, the Mid-South and Western regions also experienced striking increases in NH3 concentrations. NH3 released from livestock manure during warmer winters contributed to increased annual NH3 concentrations in the Western US. The influence of temperature on temporal evolution of NH3 concentrations was associated with synthetic N fertilizer use in the Northern Great Plains. With a strong positive impact of temperature on NH3 concentrations in the US Midwest, this region could possibly become an atmospheric NH3 hotspot in the context of future warming. Our study provides an essential scientific basis for US policy makers in developing mitigation strategies for agricultural NH3 emissions under future climate change scenarios

A Highly Selective Colorimetric Sensor for Cysteine in Water Solution and Bovine Serum Albumin

A simple colorimetric sensor, 2-bromonaphthalene-1,4-dione, has been developed for the Cysteine detection. The sensor showed its best performance in a mixture of ethanol and HEPES (5 : 5, v/v) solution at pH of 7.0. The results of UV-vis and fluorescence indicated that 2-bromonaphthalene-1,4-dione was selective and sensitive for Cysteine detection without the interference of other amino acids (Cysteine, Alanine, Arginine, Aspartinie, Glutamine, Glycine, Histidine, Isoleucine, Leucine, Lysine, Methionine, Proline, Serine, Threonine, Phenylalanine, Valine, Tryptophan, and Hydroxyproline). 2-Bromonaphthalene-1,4-dione also showed binding ability for Cysteine in bovine serum albumin and could be used as a potential colorimetric sensor among eighteen kinds of natural amino acids. Importantly, the recognition of CySH could be observed by naked eye